Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia

  • Review
  • Intervention

Authors


Abstract

Background

Patients with the cardiac arrhythmia supraventricular tachycardia (SVT) frequently present to clinicians in the prehospital and emergency medicine settings. Restoring sinus rhythm by terminating the SVT involves increasing the refractoriness of AV nodal tissue within the myocardium by means of vagal manoeuvres, pharmacological agents or electrical cardioversion. A commonly used first-line technique to restore the normal sinus rhythm (reversion) is the Valsalva Manoeuvre (VM). This is a non-invasive means of increasing myocardial refractoriness by increasing intrathoracic pressure for a brief period, thus stimulating baroreceptor activity in the aortic arch and carotid bodies, resulting in increased parasympathetic (vagus nerve) tone.

Objectives

To assess the evidence of effectiveness of the Valsalva Manoeuvre in terminating supraventricular tachycardia.

Search methods

We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1 of 12, 2012); MEDLINE Ovid (1946 to January 2012); EMBASE Ovid (1947 to January 2012); Web of Science (1970 to 27 January 2012); and BIOSIS Previews (1969 to 27 January 2012). Trials registries, the Index to Theses and the bibliographies of all relevant publications identified by these strategies were also checked.

Selection criteria

We included all randomised controlled trials (RCTs) that examined the effectiveness of the Valsalva Manoeuvre in terminating SVT.

Data collection and analysis

Two authors independently extracted the data using a standardised form. Each trial was assessed for internal validity with differences resolved by discussion. Data were then extracted and entered into Review Manager 5.1 (RevMan).

Main results

We identified three randomised controlled trials including 316 participants. All three studies compared the effectiveness of VM in reverting SVT with that of other vagal manoeuvres in a cross-over design. Two studies induced SVT within a controlled laboratory environment. Participants had ceased all medications prior to engaging in these studies. The third study reported on patients presenting to a hospital emergency department with an episode of SVT. These patients were not controlled for medications or other factors prior to intervention.

The two laboratory studies demonstrated reversion rates of 45.9% and 54.3%, whilst the clinical study demonstrated reversion success of 19.4%. This discrepancy may be due to methodological differences between studies, the effect of induced SVT versus spontaneous episodic SVT, and participant factors such as medications and comorbidities. We were unable to assess any of these factors further, nor adverse effects, since they were either not described in enough detail or not reported at all.

Statistical pooling was not possible due to heterogeneity between the included studies.

Authors' conclusions

We did not find sufficient evidence to support or refute the effectiveness of the Valsalva Manoeuvre for termination of SVT. Further research is needed and this should include a standardised approach to performance technique and methodology.

Résumé scientifique

Efficacité de la manœuvre de Valsalva pour la réversion de la tachycardie supraventriculaire

Contexte

Les patients atteints de l'arythmie cardiaque tachycardie supraventriculaire (TSV) se présentent souvent chez les cliniciens dans des contextes de médecine pré-hospitalière et de médecine d'urgence. La restauration du rythme sinusal en supprimant la TSV implique d'augmenter l'état réfractaire du nœud auriculoventriculaire au sein du myocarde par le biais des manœuvres vagales, d'agents pharmacologiques ou de la cardioversion électrique. Une technique de première ligne couramment utilisée pour restaurer le rythme sinusal normal (réversion) est la manœuvre de Valsalva (MV). Il s'agit d'une méthode non-invasive pour augmenter l'état réfractaire du myocarde en élevant la pression intrathoracique pendant une courte période, stimulant ainsi l'activité des barorécepteurs dans l'arc aortique et le glomus carotidien, aboutissant à une augmentation du tonus parasympathique (nerf vague).

Objectifs

Évaluer les preuves de l'efficacité de la manœuvre de Valsalva pour supprimer la tachycardie supraventriculaire.

Stratégie de recherche documentaire

Nous avons effectué une recherche électronique dans le registre Cochrane des essais contrôlés (CENTRAL) dans The Cochrane Library (numéro 1 sur 12, 2012) ; MEDLINE Ovid (de 1946 à janvier 2012) ; EMBASE Ovid (de 1947 à janvier 2012) ; Web of Science (de 1970 jusqu'au 27 janvier 2012) ; et BIOSIS Previews (de 1969 jusqu'au 27 janvier 2012). Nous avons également consulté les registres d'essais, l'Index des Thèses et les bibliographies de toutes les publications pertinentes identifiées par ces stratégies.

Critères de sélection

Nous avons inclus tous les essais contrôlés randomisés (ECR) ayant examiné l'efficacité de la manœuvre de Valsalva pour supprimer la TSV.

Recueil et analyse des données

Deux auteurs ont extrait les données, de façon indépendante, en utilisant un formulaire standardisé. Nous avons évalué la validité interne de chaque essai et résolu tout différend par des discussions. Les données ont ensuite été extraites et saisies dans le logiciel Review Manager 5.1 (RevMan).

Résultats principaux

Nous avons identifié trois essais contrôlés randomisés incluant 316 participants. Les trois études ont comparé l'efficacité de la MV pour la réversion de la TSV à celle d'autres manœuvres vagales dans une conception croisée. Deux études ont induit la TSV à l'intérieur d'un environnement de laboratoire contrôlé. Les participants ont arrêté tous les médicaments avant de s'engager dans ces études. La troisième étude concernait des patients se présentant au service des urgences de l'hôpital avec un épisode de TSV. Ces patients n'ont pas été contrôlés en ce qui concerne les médicaments ou d'autres facteurs avant l'intervention.

Les deux études de laboratoire ont mis en évidence des taux de réversion de 45,9 % et 54,3 %, tandis que l'étude clinique a révélé un taux de réussite de la réversion de 19,4 %. Cet écart peut être dû aux différences méthodologiques entre les études, à l'effet de la TSV induite versus TSV épisodique spontanée, et aux facteurs participants tels que les médicaments et les comorbidités. Nous n'avons pu évaluer aucun de ces facteurs de manière plus approfondie, ni les effets indésirables, car soit ils n'ont pas été décrits avec suffisamment de détails soit ils n'ont pas été rapportés du tout.

Le regroupement statistique n'a pas été possible en raison de l'hétérogénéité entre les études cliniques.

Conclusions des auteurs

Nous n'avons pas trouvé suffisamment de preuves pour soutenir ou réfuter l'efficacité de la manœuvre de Valsalva pour supprimer la TSV. Des recherches supplémentaires doivent être réalisées, lesquelles devront incorporer une approche standardisée de la technique à hautes performances et de la méthodologie.

Plain language summary

The effectiveness of the Valsalva Manoeuvre for stopping an abnormal heart rhythm

Supraventricular tachycardia (SVT) is a common heart abnormality which presents as a fast heart rate. This heart rhythm disturbance can occur in healthy individuals and may include symptoms such as chest pain, palpitations, shortness of breath, sweating and feeling faint. In rarer instances, unconsciousness may occur. The treatment of this condition is usually a combination of physical straining manoeuvres (also known as vagal manoeuvres), medications or electrical therapy (used in severe cases where blood pressure drops to a low level). A vagal manoeuvre is a term used to describe any physical intervention which results in stimulation of the tenth cranial nerve (vagus nerve), which in turn can lead to slowing of the heart rate in the setting of SVT. One such manoeuvre, the Valsalva Manoeuvre, is performed by having a patient blow into a syringe whilst lying down (face up) for fifteen seconds. This generates increased pressure within the chest cavity and triggers a slowing of heart rate which may stop the abnormal rhythm. This review examined the evidence available to see how effective the Valsalva Manoeuvre is in restoring normal heart rate (known as reversion success).

Three studies involving a total of 316 participants were included in this review. Analysis of the results showed that reversion success lies somewhere between 19.4% and 54.3%. The likelihood and severity of side effects (adverse events) could not be calculated as the studies provided insufficient information to perform this analysis. Potential side effects have been reported in other articles on the subject: these have included hypotension (sudden lowering of blood pressure) or syncope (brief loss of consciousness). No side effects were reported in the three studies reviewed here. Within the three studies reversion was achieved on completion of each Valsalva Manoeuvre.

Overall, the Valsalva Manoeuvre appears to be a simple, non-invasive method of stopping abnormal heart rhythm but its safety and overall effectiveness are difficult to quantify. Further research is required to improve the evidence surrounding this practice.

Résumé simplifié

Efficacité de la manœuvre de Valsalva pour supprimer un rythme cardiaque anormal

La tachycardie supraventriculaire (TSV) se caractérise par une accélération anormale du rythme cardiaque. Cette perturbation du rythme cardiaque peut survenir chez des individus en bonne santé et peut comprendre des symptômes tels que des douleurs thoraciques, des palpitations, un essoufflement, une transpiration et une sensation d'évanouissement. Dans des cas plus rares, il peut y avoir une perte de connaissance. Le traitement de cette pathologie est habituellement une combinaison de manœuvres d'effort physique (appelées aussi manœuvres vagales), de médicaments ou de traitement par stimulation électrique (utilisé dans les cas sévères où la pression artérielle chute jusqu'à un faible niveau). Le terme « manœuvre vagale » est utilisé pour décrire une intervention physique qui se traduit par la stimulation du dixième nerf crânien (nerf vague), qui peut à son tour entraîner le ralentissement du rythme cardiaque dans le contexte de la TSV. Pour effectuer une telle manœuvre, la manœuvre de Valsalva, le praticien doit demander au patient de souffler dans une seringue en étant en position allongée (sur le dos) pendant quinze secondes. Ceci génère une pression accrue au sein de la cavité thoracique et déclenche le ralentissement du rythme cardiaque susceptible de supprimer le rythme anormal. Cette revue a examiné les preuves disponibles pour déterminer l'efficacité réelle de la manœuvre de Valsalva pour restaurer un rythme cardiaque normal (qualifié de réussite de la réversion).

Trois études totalisant 316 participants ont été incluses dans cette revue. L'analyse des résultats a montré que la réussite de la réversion se situe à un niveau compris entre 19,4 % et 54,3 %. Le calcul de la probabilité et de la gravité des effets secondaires (événements indésirables) n'a pas été possible, car les études ont fourni des informations insuffisantes pour effectuer cette analyse. Des effets secondaires potentiels ont été rapportés dans d'autres articles sur ce sujet : ils ont compris l'hypotension (baisse soudaine de la pression artérielle) ou la syncope (perte de conscience momentanée). Aucun effet secondaire n'a été rapporté dans les trois études examinées ici. Dans les trois études, la réversion a été obtenue à la fin de chaque manœuvre de Valsalva.

Globalement, la manœuvre de Valsalva semble être une méthode non-invasive simple pour supprimer un rythme cardiaque anormal, mais sa sécurité d'emploi et son efficacité globale sont difficiles à quantifier. D'autres recherches sont nécessaires pour améliorer les preuves concernant cette pratique.

Notes de traduction

Traduit par: French Cochrane Centre 22nd March, 2013
Traduction financée par: Instituts de Recherche en Sant� du Canada, Minist�re de la Sant� et des Services Sociaux du Qu�bec, Fonds de recherche du Qu�bec-Sant� et Institut National d'Excellence en Sant� et en Services Sociaux pour la France: Minist�re en charge de la Sant�

Summary of findings(Explanation)

Summary of findings for the main comparison. Summary of findings - induced SVT
Valsalva Manoeuvre for induced SVT

Patient or population: Patients with induced SVT

Settings: Clinical laboratory

Intervention: Valsalva Manoeuvre

Comparison: Nil

OutcomesStudy

VM Performance

(posture, strain duration, pressure)

Reversion n (%)Quality of the evidence
(GRADE)
Reversion

Mehta 1988

Wen 1998

Supine, 15 and 30 seconds*, 35 mmHg

Supine, 30 seconds, 35 mmHg

19/35 (54.3)

61/133 (45.9)

⊕⊕⊝⊝
low

⊕⊕⊝⊝
low

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

* Although applying both 15 and 30 second strain durations, the Mehta study found no statistical significance of bradycardia effect (increased vagal tone) on participants when assessed in sinus rhythm.

Summary of findings 2 Summary of findings - clinical SVT

Summary of findings 2. Summary of findings - clinical SVT
Valsalva Manoeuvre for clinical SVT (patients presenting with arrhythmia)

Patient or population: Patients presenting to emergency department with SVT

Settings: Emergency department (hospital)

Intervention: Valsalva Manoeuvre

Comparison: Nil

OutcomesStudy

VM Performance

(posture, strain duration, pressure)

Reversion n (%)Quality of the evidence
(GRADE)
ReversionLim 1998Sitting**, 30 seconds, 40 mmHg12/62 (19.4)⊕⊕⊝⊝
low

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

** Although a deviation from accepted standard of performance technique, this posture is acceptable as a known method of performance in the clinical setting. Also, this posture has been demonstrated to precipitate adverse effects. The absence of reported adverse effects (such as hypotension or syncope) is not clear within the study.

Background

Description of the condition

Supraventricular tachycardia (SVT) is a generic term applied in reference to any tachycardia originating above the ventricles and which involves atrial tissue or atrioventricular (AV) nodal tissue (Medi 2009). It encompasses such arrhythmias as atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia (Wolff Parkinson White Syndrome), atrial flutter, atrial fibrillation and the sinus tachycardias. More specificity can be applied when SVT is used to describe those tachycardias which involve a nodal dependent re-entrant circuit, such as that found in atrioventricular nodal re-entrant tachycardia (AVNRT) or atrioventricular re-entrant tachycardia (AVRT) (Medi 2009). The incidence of SVT in the United States of America is approximately 35 cases per 100,000 population annually, with a prevalence of approximately 2.25 cases per 1000 population (Medi 2009). No data were identified to indicate incidence and prevalence in other regions.

These arrhythmias result from the establishment of a re-entry circuit within (or inclusive of) the atrioventricular node. They are usually episodic in nature and may result in the patient exhibiting signs and symptoms ranging from tachycardia or palpitations, shortness of breath, chest pain, anxiety, nausea and dizziness to presyncope/syncope as a consequence of reduced cardiac output (McGuire 2007; Scheinman 2005; Wellens 2003). It is these symptoms which usually precipitate an ambulance request or attendance at hospital. The establishment of AVNRT is believed to occur as a result of a premature atrial complex delivered across the AV node during the relative refractory period. As a consequence of the identification of dual nodal tract pathways for conduction of atrial impulses (fast depolarisation with slow repolarisation and slow depolarisation with fast repolarisation) (Akhtar 1993; Delacretaz 2006; McGuire 2007; Scheinman 2005; Wellens 2003), it is believed that this atrial ectopic complex stimulates a re-entry circuit.

The mechanism of AVRT differs in the existence of accessory pathways (Bundles of Kent). These conductive accessory pathways pass through the atrioventricular septum and thus provide for a larger re-entry circuit, albeit one which passes through the AV node and is similarly affected by increased vagal tone (McGuire 2007; Scheinman 2005; Wellens 2003).

A range of therapies (vagal manoeuvres, pharmacological therapy or synchronised direct current countershock therapy) are employed within emergency medicine and prehospital emergency care practice, in order to extend the refractoriness of AV nodal tissue which will result in reversion of the arrhythmia. The use of pharmacologic agents such as adenosine and calcium channel blockers (Verapamil and Diltiazem) are well known and have been the subject of systematic review and meta-analysis to determine their levels of effectiveness in this setting (Delaney 2011; Holdgate 2009). Synchronised direct current countershock therapy is generally reserved for those patients who are rapidly decompensating as a consequence of the arrhythmia and although the evidence is somewhat limited within the literature, there is support for this practice globally within medical circles. Vagal manoeuvres have also been employed for some time, with demonstrated effectiveness in reverting AVNRT and AVRT of between 12% and 54% (with a median of 25%) across the range of studies conducted (Lim 1998; Mehta 1988; Taylor 1999; Wen 1998).

The arrhythmia is usually transient and may be precipitated by such factors as cardiac disease, stimulant use, electrolyte imbalance and stress. In certain circumstances the frequency of episodes or consequences of episodic poor perfusion associated with SVT may require more significant therapies such as beta blockers or radio frequency ablation in order to improve patient quality of life. Recent studies have also identified increased troponin I enzyme levels (0.02 ng/dL to 1.05 ng/dL, mean 0.20 ng/dL) in patients suffering episodic SVT in the absence of infarction, and although no studies have quantified the potential for patient harm at this time, it is suggested that these elevated troponin I levels may be linked with myocardial damage (Carlberg 2011; Redfearn 2005; Zellweger 2003). These studies also suggest that enzyme levels rise with increasing age of the patient, although the consequences are again at this time unquantified (Carlberg 2011; Redfearn 2005; Zellweger 2003).

Description of the intervention

The Valsalva Manoeuvre was first published by Antonio Maria Valsalva in 1704, in his seminal work De Aura Humane Tractatus, as a means of expelling pus from the middle ear of a patient (Jellinek 2006; Junqueira 2007; Waxman 1980; Yale 2005). It has continued to retain relevance in modern medicine across a range of medical and scientific disciplines. Although it is unclear exactly when the manoeuvre was first applied to terminating haemodynamically stable SVT (in the form of AVNRT or AVRT), it is likely to have coincided with the advent of the ECG (Einthoven 1906). The Valsalva Manoeuvre constitutes three specific elements in order to provide a maximum effect, as follows (Taylor 2004).

  • Posture of the patient (supine).

  • Pressure generation within the intrathoracic cavity (40 mmHg).

  • Duration of strain (15 seconds).

These elements provide a set of values which, when adhered to, should maximise parasympathetic (vagal) response and cause reversion of the arrhythmia (in the absence of any compliance or other patient issues which may affect performance or the nature of effect).

The Valsalva Manoeuvre is defined by four phases of activity, first described by Hamilton et al in 1936, as follows (Junqueira 2007).

  • Phase one can be defined by a transient increase in pressure within the thoracic aorta, coupled with a compensatory decrease in heart rate triggered by the baroreceptors within the aortic arch. This pressure increase results from the compressive effect of the generated intrathoracic pressure on the thoracic aorta.

  • Phase two is defined by the end of this transient period, resulting in decreasing aortic pressure and increasing heart rate.

  • Phase three occurs at the end of the strain phase of the VM (and includes a resulting decrease in intrathoracic pressure exerted on the aorta), leading to a brief pressure drop within the aorta and a compensatory rise in heart rate.

  • Phase four occurs as a result of increased venous return and a subsequent increase in preload, resulting in increased aortic pressure as cardiac output is elevated, and a compensatory decrease in heart rate.

The Valsalva Manoeuvre has been selected for review as it provides a simple, quantifiable (method) and non-invasive means of inducing increased vagal tone. Other manoeuvres such as Carotid Sinus Massage and Dive Reflex therapy have limitations within the prehospital setting regarding patient safety, standardisation and reproducibility, and the logistics of application (for example, the acquisition and use of ice).

How the intervention might work

The Valsalva Manoeuvre is a simple, quantifiable and non-invasive method of increasing vagal tone; thereby increasing the refractory period of myocardial cells in order to terminate the established nodal re-entry circuit. The manoeuvre was traditionally performed by expiring against a closed glottis to increase intrathoracic pressure, thereby triggering baroreceptor activity and increased vagal tone. However, this also has potentially deleterious side effects such as increased intra-occular pressure and profound hypotension as a consequence of unfettered vagal stimulation (Junqueira 2007; Looga 2004; Taylor 2004; Vaisrub 1974). Since Rushmer introduced the measurement of intraoral pressure in 1947 (Junqueira 2007), the manoeuvre is now more commonly described and instructed as an exhalation against a defined pressure (measurable) in order to avoid significant side effects and to improve performance and patient safety. Maximum vagal response occurs on release of the sustained intrathoracic pressure, which occurs in phase four of the VM, and it is at this point that reversion of the arrhythmia is most likely to occur (Looga 2004; Waxman 1980). Recently, efforts have been made to provide a standard of instruction of the VM for use in the haemodynamically stable patient suffering AVNRT, including the use of a 10 ml syringe to generate the 40 mmHg pressure required (Taylor 2004; Smith 2009a).

Why it is important to do this review

Currently, there are a plethora of definitions of Valsalva performance and it is used across a variety of medical and scientific disciplines to promote different effects (cardiac or non-cardiac) (Smith 2009b). The effectiveness of the VM is challenged by available interventional and observational non-randomised clinical studies (7.3% to 54% of study sample) (Taylor 1999; Waxman 1980; Taylor 2004) and the plethora of definitions of method (specifically variations in the three elements of posture, pressure and duration) (Smith 2009b). Through this review, we hoped to ascertain the nature of evidence available to demonstrate VM effectiveness, and the need for further study to define the effectiveness of the VM for the development of future therapy regimens in the treatment of SVT.

Objectives

To assess the evidence of effectiveness of the Valsalva Manoeuvre in terminating supraventricular tachycardia.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) of VM effectiveness in terminating SVT.

Types of participants

Participants whose normal cardiac rhythm is sinus rhythm and who have no known cardiac disease, with acute onset or induced episodes of haemodynamically stable atrioventricular nodal reentrant tachycardia (AVNRT) or atrioventricular reentrant tachycardia (AVRT).

Types of interventions

The definition of a Valsalva Manoeuvre for the purpose of this review is a physical manoeuvre which has three elements (posture, strain duration and pressure), and when performed results in an increase in intrathoracic pressure and increased refractoriness of AV nodal tissue. Although the model of practice described within the Intervention Description is preferred, a range of values are currently used within the literature to describe the Valsalva Manoeuvre. As such, we accepted the following values for this review:

  • posture (supine, or supine with legs elevated);

  • strain duration (15 to 30 seconds);

  • pressure (30 mmHg to 50 mmHg).

Comparison: Only those study results identifying the effectiveness of the VM for SVT reversion were included in this review, whilst reported comparisons of effectiveness of VM with other vagal manoeuvres (such as Carotid Sinus Massage or Dive Reflex) within included studies were excluded in accordance with the aims of the review.

Types of outcome measures

Studies were eligible for inclusion if they reported any of the following outcome measures:

Primary outcomes

Reversion of SVT to a sinus rhythm.

Secondary outcomes

1. Failure to revert SVT to a sinus rhythm, followed by:

  • repeated attempts at VM or other vagal manoeuvres;

  • pharmacological intervention; or

  • direct current countershock therapies.

2. Cardiovascular effects of VM performance (e.g. hypotension, bradycardia).

3. Frequency and severity of adverse events resulting from application of the VM.

4. Mortality resulting from the VM.

Search methods for identification of studies

Electronic searches

We searched the following sources:

  • Cochrane Central Register of Controlled Trials (CENTRAL), in The Cochrane Library, Issue 1 of 12 (2012).

  • MEDLINE OVID (1946 to January Week 3 2012).

  • EMBASE & EMBASE Classic OVID (1947 to 2012 Week 04).

  • Conference Proceedings Citations Index (ISI Web of Science) (1970 to 27 January 2012).

  • Conference abstracts (ISI BIOSIS Previews) (1969 to 27 January 2012).

We also searched for adverse events using:

  • MEDLINE OVID (1946 to January Week 3 2012).

The search strategies are presented in Appendix 1. There were no language restrictions applied to the searches.The MEDLINE and EMBASE strategies were combined with the Cochrane sensitive-maximising RCT filter (Lefebvre 2011).

Searching other resources

  • World Health Organization International Clinical Trials Registry Platform (ICTRP): http://apps.who.int/trialsearch/default.aspx (Search terms used: Valsalva, Manoeuvre. Accessed 22 February 2012).

  • Clinical Trials Registry: http://www.anzctr.org.au/TrialSearch.aspx (Search terms used: Valsalva, Manoeuvre. Accessed 22 February 2012).

We also handsearched the following literature:

  • Index to Theses.

  • International Standard Randomised Controlled Trial Number Register (ISRCTN).

  • The bibliographies of all relevant publications identified by the electronic and handsearches.

Data collection and analysis

Selection of studies

The search results (titles and abstracts) were screened by two authors (GS and KD). The results from the search strategy are presented as a flowchart (Figure 1) based on the Quorum statement (Lefebvre 2011). Titles and abstracts identified by the search strategy were screened independently by both reviewers. All potentially relevant studies were retained and the full texts of these studies were examined to determine which studies satisfied the inclusion criteria. A two stage process was used to select studies for inclusion: (i) independent selection (without blinding) by two authors (GS and KD) to short list potential studies, (ii) a final group selection involving discussion between two authors (GS and KD) to define which studies met the inclusion criteria. Arbitration by a third author to resolve any disagreements was not required.

Figure 1.

Search results

Data extraction and management

Data extraction was carried out independently by the same reviewers using pre-defined data extraction forms. No RCT studies were identified requiring translation to English. No important data were missing which would require contacting the original authors of the study for clarification. Data extraction was performed by two authors (GS and KD) independently without blinding and using a paper data collection form to record and tabulate search results. The results were compared, discussed and collated prior to being transcribed to an electronic spreadsheet for tabulation. There were no disagreements regarding applicability for inclusion or exclusion.

Assessment of risk of bias in included studies

We used the risk of bias assessment guidelines in the Cochrane Handbook for Systematice Reviews of Interventions (Higgins 2011) to address the following sources of potential bias:

  • selection bias;

  • performance bias;

  • attrition bias; and

  • detection bias.

Each of these was addressed using a three point grading (high, unclear, or low) to measure the following:

  • allocation concealment (did the method enable concealment to the point of assignment);

  • blinding to outcome assessment (where the investigators were aware of the treatment allocation);

  • adequacy of controls (did the study provide for equal numbers of treatment and control subjects);

  • adequacy of follow up (did the method account for all participants including withdrawal, dropout or protocol deviation);

  • intention-to-treat analysis (did the study provide for post-treatment bias control through an intention-to-treat analysis, follow up of withdrawals and completeness, and analysis of results by original treatment and treatment given).

A third author (AM) arbitrated any disagreement regarding risk or bias assessment.

Measures of treatment effect

Unit measures were assigned using common terms to all papers as follows:

  • reversion rate;

  • time to reversion (number of VM attempts);

  • relapse rate;

  • minor adverse events;

  • major adverse events.

Unit of analysis issues

The unit of analysis was the individual participant. Consultation with an appropriately qualified statistician was not required as no unit of analysis issues arose.

Dealing with missing data

Contact with the study authors was not required as no data were missing.

Assessment of heterogeneity

The presence of high levels of clinical and methodological heterogeneity resulted in studies being presented using descriptive statistics only.

Assessment of reporting biases

Measurement of reporting bias was assessed by the following:

  • clear definition of inclusion/exclusion criteria;

  • clear definition of outcome measure(s);

  • reported accuracy, precision and observer variation of outcome measures;

  • appropriately timed outcome measures.

Data synthesis

We were unable to synthesise data statistically and results are demonstrated using descriptive statistics only.

Subgroup analysis and investigation of heterogeneity

Subgroup analysis was not undertaken due to insufficient specific data within the available studies.

Sensitivity analysis

No sensitivity analysis was possible, as no meta-analysis was undertaken due to high level clinical and methodological heterogeneity. Descriptive statistics were used to present results.

Results

Description of studies

See: Characteristics of included studies.

See: Characteristics of included studies.

Results of the search

The literature search identified 609 potentially relevant studies. After filtering for duplication, 169 studies were excluded. Each of the remaining 440 studies were examined (title and abstract), and those which were either not an RCT or which did not demonstrate effectiveness of VM in reverting SVT were excluded. Three studies were retrieved for more detailed evaluation and were subsequently included in the review. The literature search results are described graphically in Figure 1. Two studies (Mehta 1988; Wen 1998) included a cross-over design where an alternative intervention was used irrespective of primary intervention success. The Lim 1998 study was also a cross-over design, where subsequent intervention was dependent upon failed primary intervention in reversion of SVT. This offered challenges in providing analysis appropriate for the question of VM effectiveness in terminating SVT, as each RCT used varied methodology (multiple attempts of a variety of vagal manoeuvre interventions and performance techniques). As a result, heterogeneity of methods precluded meta-analysis. It was not possible to provide descriptions of reported adverse effects of VM used in the management of SVT as none were identified as a result of the search. The results of the adverse effects search are described graphically in Figure 2.

Figure 2.

Search results for adverse effects

Included studies

The three selected RCTs were conducted in three different countries (Singapore, England and Taiwan), and comprised 316 participants. All three studies reported a primary outcome measure of reversion (or effectiveness) of VM used in terminating SVT. Each study included application of the VM between one and three times to achieve effect. All studies included a cross-over design and the nature of this design enabled descriptive analysis of two of these (Mehta 1988; Wen 1998). The Lim 1998 study reported patients in the clinical setting presenting with SVT to an emergency department, whereas the Mehta 1988 and Wen 1998 studies described induced SVT in participants with significant control of other variables (such as cessation of medication for adequate half-life time prior to participation in the study). It is possible that an induced SVT (by programmed electrical stimulation) in a healthy adult may be more susceptible to reversion by vagal manoeuvres than a patient presenting to hospital who is experiencing an episode of SVT (of varied duration). The use of induced SVT may not represent clinical presentations of SVT, as an arrhythmia generated by a period of external electrical stimulation is likely to self resolve more rapidly than one which is triggered or maintained by a stimulus from within the myocardium, although this is not clearly evidenced within the available literature. As a consequence, the reversion rate demonstrated by the Lim 1998 study is more likely to represent clinical effectiveness. It is also likely that individuals who have a history of SVT are more likely to be familiar with the VM and its correct application. This suggests that these individuals would be more likely to be adept at applying the VM than healthy participants within the two laboratory studies, which may affect the results of these studies. It was not possible to gauge the potential effect of this factor within this review. Also, given the cross-over design of each study, this review data represents primary intervention (VM) reversion within the available RCT data, and is not affected by other vagal manoeuvres. It was decided that both the Mehta 1988 and Wen 1998 studies provided an appropriate inclusion defined by the review question, whilst the Lim 1998 study added value as a clinical application of VM in patients presenting with SVT to an emergency department and so is presented separately.

Excluded studies

No identified RCTs were excluded.

Risk of bias in included studies

The details of quality assessment based upon the Cochrane Handbook for Systematic Reviews of Interventions method (Higgins 2011) are presented in the table 'Characteristics of included studies'. In addition, a brief analysis of the risk of bias of included studies can be found below. No studies demonstrated adequate allocation concealment. In addition, blinding was not possible due to the nature of the intervention.

Allocation

There is a high risk of selection bias within the Medi 2009 and Wen 1998 studies, as allocation concealment was not reported. The Lim 1998 study contained an unclear risk of selection bias as the use of cards in an envelope (to be selected by a staff nurse) with the intervention written on each appears inadequate to demonstrate appropriate random allocation of participants to intervention.

Blinding

There was no evidence of blinding in any of the three studies included in this review. It is worth noting that the nature of the intervention (performance of a vagal manoeuvre) prevents blinding of investigators or participants to either intervention or effect. Thus, performance bias was not practical within the three studies and detection bias was not reported in any of the three studies.

Incomplete outcome data

There was a low risk of attrition bias within all of the three studies included in this review, as results included outcome reporting for all participants in each study.

Selective reporting

There was a low risk of reporting bias within all of the three studies included in this review, as all outcomes for each intervention were reported in all cases.

Other potential sources of bias

None noted.

Effects of interventions

See: Summary of findings for the main comparison Summary of findings - induced SVT; Summary of findings 2 Summary of findings - clinical SVT

Each of the three identified RCT studies used a cross-over design to compare effectiveness of the VM against other vagal manoeuvres (the dive reflex (HDR) and carotid sinus massage (CSM)). As this review was specifically to address the effectiveness of VM for SVT reversion, its comparative effect against other vagal manoeuvres has not been assessed or analysed here. Also, heterogeneity of method between studies would make such a comparison difficult. All three RCTs provided adequate data on the primary outcome of the review (termination of SVT) and as a consequence, the study investigators were not contacted for further information by the authors of this review. The data within the included RCT studies did not provide an opportunity to report on reversion success, adverse effects and mortality outcomes. The absence of reported data prevented other listed outcomes from being assessed. Those outcomes which were able to be assessed are reported as follows.

Reversion rate

The Mehta 1988 and Wen 1998 studies provided reversion success rates of 54.3% (19/35) and 45.9% (61/133), respectively, whilst the Lim 1998 study reported reversion success of 19.4% (12/62). Statistical pooling was not possible as a result of heterogeneity between included studies.

Adverse effects

We were unable to calculate the nature of significant cardiovascular effects, such as hypotension and bradycardia resulting from VM application to SVT, as these were not reported. Within the Lim 1998 study, a single patient was reported to be diagnosed with myocardial infarction, but it is unclear if this was the result of the SVT or precipitated the arrhythmia.

Mortality

No deaths were reported in any of the studies. As a consequence, the mortality rate for VM use in SVT within this review is zero.

Discussion

Summary of main results

The Mehta 1988 and Wen 1998 studies provided reversion success rates of 54.3% (19/35) and 45.9% (61/133), respectively, whilst the Lim 1998 study reported reversion success of 19.4% (12/62). There were important methodological differences and significant heterogeneity between the studies which prevented meta-analysis. Also, sufficient validity could not be ascribed to the primary studies. This has resulted in only descriptive statistics for VM reversion of SVT being reported.

Side effects, cardiovascular effects and mortality associated with VM use for SVT were not reported in the three included studies, precluding reporting or analysis.

Overall completeness and applicability of evidence

The data on the primary outcome were available for analysis. The identified studies specifically assessed the effectiveness of the VM in reverting SVT and so were applicable. It was noted that two of the studies (Mehta 1988; Wen 1998) provided assessment in the setting of induced SVT, whereas the third study assessed the effectiveness of VM in patients presenting to an emergency department with an episode of SVT. This third study offered more relevant data for the clinical setting. Though the identified studies are somewhat dated, it is unlikely that we have failed to detect a relevant study given the comprehensive search strategy.

Quality of the evidence

The quality of evidence was generally poor, as a consequence of sample size and number of available RCTs. Also, the nature of variability in performance of (and indeed what quantified) a VM for this application ensured that it was not possible to make a definitive analysis of effectiveness of the VM for termination of SVT. Whilst all three studies provided a primary outcome (reversion), there was little or no information regarding other outcomes (mortality, adverse effects and cardiovascular effects). Precision of the results is low, with confidence intervals specific to reversion not reported in two studies. Generalisability is challenged by the setting of the Mehta 1988 and Wen 1998 studies, and the Lim 1998 study provides the only example of clinical applicability.

At this time there is no universally accepted standardised VM, although the method stated within the Description of the intervention section is often used in the clinical setting. Future studies should consider using this method to improve homogeneity between studies and the generalisation of results.

Potential biases in the review process

None identified.

Agreements and disagreements with other studies or reviews

There is insufficient evidence available to determine if these review findings represent concurrence, as there are no other systematic reviews of this intervention.

Authors' conclusions

Implications for practice

The results of the three RCTs examined within this review are insufficient to support a definitive assessment of effectiveness for use of the VM to terminate SVT in patients with this condition. However, given the reversion rates of 54.3% and 45.9% in the laboratory studies, and 19.4% within the clinical study, it is possible to suggest that the VM should be considered useful as a safe (in the absence of and reporting of adverse effect data), non-invasive first-line measure for attempting reversion of haemodynamically stable SVT prior to the use of pharmacological interventions. The reversion rate of the third (clinical) study is less than those of the induced SVT studies, and this leads us to believe that reversion success of the VM for SVT is likely to lie in the lower realm of the results demonstrated.

Implications for research

There are opportunities to improve the quality of available evidence described by this review. The prevalence of patients presenting with SVT enables large sample sizes to be readily obtained for future studies, demonstrating a methodological rigour. Consideration should be given to the development and acceptance of a standardised VM for the termination of SVT, as this would aid in improving homogeneity between studies. There is also a need to identify factors which may impact upon VM effectiveness (such as diabetes mellitus, hypertension and CAD), the impact of age on parasympathetic tone generation, the impact of respiratory disease (such as COPD and asthma) on the patients' ability to generate appropriate intrathoracic pressure for a VM, and future studies should consider the following:

  • employing a standardised method of performing a VM;

  • the impact of age on vagal tone generation;

  • examining the impact of other disease on VM effect (such as diabetes, hypertension, cardiovascular disease, respiratory disease).

Acknowledgements

Sharon Kramer, Systematic Review Trainer, Australasian Cochrane Centre, for her invaluable assistance in guiding the authors through the review process.

Data and analyses

Download statistical data

This review has no analyses.

Appendices

Appendix 1. Primary search strategy

CENTRAL

#1           MeSH descriptor Valsalva Maneuver, this term only

#2           (valsalva*)

#3           MeSH descriptor Vagus Nerve explode all trees

#4           (vagal)

#5           MeSH descriptor Vagus Nerve Stimulation, this term only

#6           (vagus)

#7           (#1 OR #2 OR #3 OR #4 OR #5 OR #6)

#8           MeSH descriptor Tachycardia, Supraventricular explode all trees

#9           MeSH descriptor Tachycardia, Paroxysmal, this term only

#10         MeSH descriptor Tachycardia, Reciprocating explode all trees

#11         (supraventric* near/4 arrhythmi*)

#12         (supra-ventric* near/4 arrhythmi*)

#13         (tachyarrhythmi*)

#14         (svt)

#15         (avrt)

#16         (avnrt)

#17         (tachycardi*)

#18         (#8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16 OR #17)

#19         (#7 AND #18)

 

MEDLINE OVID

1     Valsalva Maneuver/

2     valsalva*.tw.

3     exp Vagus Nerve/

4     vagal.tw.

5     Vagus Nerve Stimulation/

6     vagus.tw.

7     or/1-6

8     exp Tachycardia, Supraventricular/

9     Tachycardia, Paroxysmal/

10     exp Tachycardia, Reciprocating/

11     (supraventric* adj4 arrhythmi*).tw.

12     (supra-ventric* adj4 arrhythmi*).tw.

13     tachyarrhythmi*.tw.

14     svt.tw.

15     avrt.tw.

16     avnrt.tw.

17     tachycardi*.tw.

18     or/8-17

19     7 and 18

20     randomised controlled trial.pt.

21     controlled clinical trial.pt.

22     randomized.ab.

23     placebo.ab.

24     drug therapy.fs.

25     randomly.ab.

26     trial.ab.

27     groups.ab.

28     20 or 21 or 22 or 23 or 24 or 25 or 26 or 27

29     exp animals/ not humans.sh.

30     28 not 29

31     19 and 30

  

EMBASE OVID

1     Valsalva Maneuver/

2     valsalva*.tw.

3     exp Vagus Nerve/

4     vagal.tw.

5     Vagus Nerve Stimulation/

6     vagus.tw.

7     or/1-6

8     exp Tachycardia, Supraventricular/

9     Tachycardia, Paroxysmal/

10     exp Tachycardia, Reciprocating/

11     (supraventric* adj4 arrhythmi*).tw.

12     (supra-ventric* adj4 arrhythmi*).tw.

13     tachyarrhythmi*.tw.

14     svt.tw.

15     avrt.tw.

16     avnrt.tw.

17     tachycardi*.tw.

18     or/8-17

19     7 and 18

20     random$.tw.

21     factorial$.tw.

22     crossover$.tw.

23     cross over$.tw.

24     cross-over$.tw.

25     placebo$.tw.

26     (doubl$ adj blind$).tw.

27     (singl$ adj blind$).tw.

28     assign$.tw.

29     allocat$.tw.

30     volunteer$.tw.

31     crossover procedure/

32     double blind procedure/

33     randomized controlled trial/

34     single blind procedure/

35     20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 or 32 or 33 or 34

36     (animal/ or nonhuman/) not human/

37     35 not 36

38     19 and 37

 

Web of Science & BIOSIS Previews

# 15   #14 AND #13

# 14   Topic=((random* or blind* or allocat* or assign* or trial* or placebo* or crossover* or cross-over*))

# 13   #12 AND #4

# 12   #11 OR #10 OR #9 OR #8 OR #7 OR #6 OR #5

# 11   Topic=(tachycardi*)

# 10   Topic=(avnrt)

# 9   Topic=(avrt)

# 8   Topic=(svt)

# 7  Topic=(tachyarrhythmi*)

# 6   Topic=(supra-ventric* near/4 arrhythmi*)

# 5   Topic=(supraventric* near/4 arrhythmi*)

# 4   #3 OR #2 OR #1

# 3   Topic=(vagus)

# 2   Topic=(vagal)

# 1  Topic=(valsalva*)

Appendix 2. Primary adverse effects search strategy

MEDLINE (OVID) search strategy filter for adverse effects as per the Loke 2011 method described within the Cochrane Handbook for Systematic Reviews of Interventions:

 1. Valsalva Maneuver/ae

2. exp Vagus Nerve/ae

3. Vagus Nerve Stimulation/ae

4. or/1-3

5. Vagus.tw.

6. valsalva*.tw.

7. vagal.tw.

8. or/5-7

9. adverse effect*.tw

10. side effect*.tw

11. complication*.tw

12. safe*.tw

13.effect*.tw

14. outcome*.tw

15. event*.tw

16. reaction*.tw

17. or/9-16

18. 8 AND 17

19. 1 OR 2 OR 3 OR 18

20. supraventricular tachycardia*.tw

21. 19 and 20

Contributions of authors

GS, KD and AM (protocol preparation, data search, data acquisition, data filtering, preparation of final report, and update of review).

GS, KD, DT, AM and KC (data analysis).

Declarations of interest

The authors declare no interest, financial or otherwise in the completion, conduct or outcomes of this review.

Differences between protocol and review

As no RCT studies were identified with participants aged > 18 years only, it was unanimously decided that the protocol should be varied to enable inclusion of those studies which included paediatric participants to enable this review to report what is currently known.

Due to the nature of identified RCT studies included in this review, it was necessary to change both the title and objectives of the review to remove the terms "in the prehospital and emergency medicine settings" which reflects more appropriately what was able to be assessed from within the published evidence.

The adverse effects search strategy differs between protocol and review. As a result of the VM being used as a therapeutic and diagnostic tool across many scientific and medical disciplines, it was necessary to make changes to the adverse effects search strategy in order to refine the results to VM application to the SVT setting.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Lim 1998

Methods

Country: Singapore

Randomisation method: not stated

Participants

Age: 10 to 90 years (63 male, 63 female)

VM Group: 62

CSM Group: 86

Inclusion criteria: SVT (AVNRT or AVRT)

Exclusion criteria: Presenting arrhythmia other than AVNRT or AVRT

Interventions

VM performance: 40 mmHg pressure, 30 seconds duration, posture not reported.

Number of VM attempts: single attempt.

Group 1: Valsalva manoeuvre  → Right CSM  → Left CSM

Group 2: Valsalva manoeuvre  → Left CSM  → Right CSM

Group 3: Right CSM  → Left CSM  → Valsalva manoeuvre

Group 4: Left CSM → Right CSM  → Valsalva manoeuvre

OutcomesReversion to sinus rhythm for greater than two hours (monitored in ED on ECG for this time).
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "Patients were randomly assigned". "Each of these choices was written on a small card and placed in an envelope. The staff nurse in charge of the patient's care would draw one of these cards from the envelope".

Comment: Probably not done.

Allocation concealment (selection bias)Unclear risk

Quote: "Each of these choices was written on a small card and placed in an envelope. The staff nurse in charge of the patient's care would draw one of these cards from the envelope".

Comment: Probably not adequate.

Blinding of participants and personnel (performance bias)
All outcomes
High risk

Due to the nature of the interventions, participants and personnel could not be blinded.

Comment: Not done.

Blinding of outcome assessment (detection bias)
All outcomes
High risk

Not reported.

Comment: Probably not done.

Incomplete outcome data (attrition bias)
All outcomes
Low riskOutcomes reported for 148/148 participants.
Selective reporting (reporting bias)Low riskOutcomes for reversion and recurrence were reported for all participants.
Other biasUnclear riskN/A

Mehta 1988

Methods

Country: United Kingdom

Randomisation method: not stated

Participants

Age: 16 to 69 years (20 male, 15 female)

5 Groups with 35 participants allocated to each group

Inclusion criteria: repeatedly inducible haemodynamically stable SVT (AVNRT or AVRT)

Exclusion criteria: unsustainable induced SVT for > 5 minutes, tachyarrhythmias other than AVNRT or AVRT

Interventions

VM performance: 35 mmHg pressure, 15 and 30 seconds duration, supine posture

Number of VM attempts: maximum of two attempts** for each of three episodes of stimulated SVT

Group 1: supine VM

Group 2: standing VM

Group 3: right CSM

Group 4: left CSM

Group 5: diving reflex

OutcomesReversion (in 2 out of 3 attempts). No time frame is given for length of reversion, as these SVT episodes are induced.
Notes** a second attempt was performed if the participant failed to revert on the first attempt.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "The manoeuvres were performed in random order". "The manoeuvres were performed first during sinus rhythm or first during tachycardia in random order".

Comments: Probably not done.

Allocation concealment (selection bias)High risk

Not reported

Comment: Probably not done.

Blinding of participants and personnel (performance bias)
All outcomes
High risk

Due to the nature of the interventions participants and personnel could not be blinded.

Comment: Not done.

Blinding of outcome assessment (detection bias)
All outcomes
High risk

Not reported

Comment: Probably not done.

Incomplete outcome data (attrition bias)
All outcomes
Low riskOutcomes reported for all interventions (35/35) and outcomes except diving reflex in sinus rhythm (32/35).
Selective reporting (reporting bias)Low riskOutcomes for reversion of SVT for supine and standing VM, right and left CSM, and DR were reported. Heart rate responses in sinus rhythm for the above interventions were also reported.
Other biasUnclear riskN/A

Wen 1998

  1. a

    Abbreviations:

    VM: Valsalva Manoeuvre

    CSM: Carotid Sinus Massage

    DR: D ive Reflex

    SVT : Supraventricular Tachycardia

    AVNRT: Atrio-Ventricular Nodal Re-entry Tachycardia

    AVRT: Atrio-Ventricular Re-entrant Tachycardia

    mmHg: millimetres of mercury

    ED: Emergency Department

    ECG: Electo-Cardio Graph

    N/A: Not Applicable

Methods

Country: Taiwan, ROC

Randomisation method: not stated

Participants

Age: 14 to 72 years (48 male, 85 female)

6 Groups with 133 participants allocated to each group

Inclusion criteria: repeatedly inducible haemodynamically stable SVT (AVNRT or AVRT)

Exclusion criteria: unsustainable (> 5 minutes) induced SVT, tachyarrhythmias other than AVNRT or AVRT

Interventions

VM performance: 35 mmHg pressure, 20 seconds duration, supine posture

Number of VM attempts: three attempts for each of three stimulated episodes of SVT

Group 1: VM

Group 2: CSM

Group 3: ice-to-face

Group 4:VM + ice-to-face

Group 5: VM + CSM

Group 6: CSM + ice-to-face

OutcomesReversion in two out of three attempts. No time frame is given for length of reversion, as these SVT episodes are induced.
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk

Quote: "The manoeuvres were performed in random order".

Comment: Probably not done.

Allocation concealment (selection bias)High risk

Not reported.

Comment: Probably not done.

Blinding of participants and personnel (performance bias)
All outcomes
High risk

Due to the nature of the interventions participants and personnel could not be blinded.

Comment: Not done.

Blinding of outcome assessment (detection bias)
All outcomes
High risk

Not reported.

Comment: Probably not done.

Incomplete outcome data (attrition bias)
All outcomes
Low riskOutcomes reported for all interventions and outcomes (133/133).
Selective reporting (reporting bias)Low riskOutcomes for reversion of SVT for VM, CSM and ice-to-face were reported.
Other biasUnclear riskN/A