Minimum requirements in emergency kits for bailout strategies in TAVR complications

Abstract Introduction The proportion of patients with symptomatic severe aortic stenosis treated by transcatheter aortic valve replacement (TAVR) is increasing, driven by favorable outcomes from randomized trials and current valve guidelines recommendations. Despite device and technique improvements having reduced procedural morbidities, complications during or immediately after TAVR still carries significant mortality risk. Methods We propose a check‐list of essential items to anticipate potentially life‐threatening complications in TAVR. Results Purpose of this review is to discuss the most common life‐threatening complications during TAVR from a troubleshooting perspective, depicting the minimum required equipment needed in emergency situations. Conclusions Prevention of complications remains the most important strategy to optimize outcomes in TAVR procedures. Each specialized Center should institute and make easily accessible standardized emergency kits for the most common life‐threatening conditions during TAVR that should be readily available in the cath‐lab or hybrid operating room.

Even though technological improvements and increased operator experience have led to a decrease in major periprocedural complications, 2-5 the need of bailout strategies to manage potentially lifethreatening complications remains. 6 Currently, there are no specific international guidelines focused on the management of the most common life-threatening TAVR complications. Nevertheless, a prompt and standardized approach to each individual type of complications along with preassembled emergency kits seem to be useful.
Based on our experience of over more than 1000 TAVR cases at our respective institutions, we have developed a strategy of having different preassembled emergency kits readily available off the shelf to manage a wide range of complications.

| METHODS
We reviewed the main periprocedural TAVR complications and described the minimum requirements in emergency kits (Table 1) and the subsequent bailout strategies in a pragmatic easy-to-understand manner.

| High degree/complete atrioventricular (AV) blocks
Due to the proximity of the AV node to the aortic valvular complex, postprocedural high-degree or complete AV block requiring permanent pacemaker implantation are one of the most common complications after TAVR, ranging from 2% to 51% (average 17%). 7 The diagnosis is easily achieved by intraprocedural electrocardiogram monitoring; most frequently the electric disturbances appear after the valve deployment; in a small percentage the blocks are delayed, hours or even days after the procedure.
A bailout strategy for managing high-degree blocks is crucial, especially in the setting of minimalist TAVR approach with pacing T A B L E 1 Basic emergency kits for managing the most common complications during transfemoral TAVR through the left ventricular wire. In the latter case, especially when implanting self-expanding devices that require guidewire maneuvering to and from the left ventricle, it is important assuring that major heart rhythm disturbances have not developed before removing the wire.

| Cardiac tamponade/pericardial effusion
One of the most fearful complications after TAVR is hemopericardium ( Figure 1A); any time of the procedure could be complicated by pericardial effusion due to left or right ventricular perforation, annular rupture, or injury from temporary pacemaker insertion or withdrawal. 8 The key for the success is to quickly evacuate the pericardial space due to cardiac tamponade and possibly facilitate the clotting process. The diagnosis is made by clinical and echocardiographic evaluation (new onset and increasing pericardial effusion on transoesophageal or transthoracic echocardiogram with progressive hypotension unresponsive to fluid administration).
Two tools are mandatory in this context: a pericardiocentesis set and a cell saver.

| Pericardiocentesis set
The emergent pericardial drainage could be performed under transesophageal, transthoracic and/or fluoroscopic guidance. Full reversal of the anticoagulation state by the infusion of protamine should be pursued on a case-by-case basis since it can risk thrombus formation.
In the normal TAVR scenario a fluoroscopic-guided procedure is often performed using the antero-posterior and lateral projections to remark the pericardial shadow. 9 A mix saline-iodinate medium (e.g., 70%/30%, respectively) may help in verify the correct intra- In case of a more severe bleeding, a direct blood reinfusion through the femoral introducer sheath could be performed after heparin readministration.
In case of intractable bleeding a prompt sub-xiphoid surgical drainage or full sternotomy is mandatory. A good rule of thumb is to observe the amount of bleeding in the first 5 min. If the bleeding is more than 300 ml per minute after 2-3 min, or if the patient remains severely unstable, then conversion to surgery is mandatory. In our practice, we deliver a full dose of heparin before sternotomy to establish peripheral cardiopulmonary bypass (femoral-femoral), with a standard set including pump, oxygenator, reservoir and multiple suction lines, because in most occasions the lesion leading to massive bleeding requires full mechanical support and the possibility to reinfuse the aspirated blood drainage. On some occasions the lesion can be repaired on the beating heart, otherwise a cardioplegic arrest is needed to facilitate a complex repair (annular rupture, aortic dissection, large ventricular injury). In case of myocardial lesions from guidewire perforation we recommend using large sutures with large needles and large Teflon pledgets to mattress the ventricular wall, since the bleeding spot appearing on the surface is often larger than it appears.

| Cell saver
Cell savers are instruments that collect and gather blood lost during surgery or complex interventional procedures. The red blood cells (RBCs) are washed with normal saline and concentrated to make an approximate 225 ml unit with a hematocrit of approximately 55% that can be stored or immediately reinfused to the patient. This tool is effective to promptly restore the normotonic volemia.
The system works by the connection of the Pigtail catheter draining the hemopericardium to an outflow-line to the central venous access.
The cell saver is useful given its quick setup, reducing the delay in seeking allogenic blood units. Cell saver could be also useful in cases of complex surgical correction.

| Device embolization
The VARC-3 3 defines 10 valve migration as the dislodgement of the transcatheter valve after initial correct positioning; the valve prosthesis moves upwards or downwards, within the aortic annulus from its initial position, with or without consequences.
Valve embolization refers to the valve prosthesis movement during or after the deployment such that it loses its contact with the aortic annulus.
Device embolization is currently a relatively rare complication of TAVR (0.92% in the largest multicenter TRAVEL registry), 11 mainly due to device improvements and more accurate preprocedural sizing and intraprocedural deployment. However, device migration or embolization can still occur either in the upward (aortic) or downward (left ventricular outflow tract) direction requiring urgent management. Aortic embolization remains the most common direction (70%-80%) of device dislodgement.
More than 80% of valve migration is immediately periprocedural, 15% within the first hour and only 3% thereafter. The diagnosis is made from fluoroscopy and echocardiogram.
In most cases the preferred management is to address the issue via catheter-based approaches. 12 Three are the main bailout strategies to be pursuit: 1. Repositioning the transcatheter heart valve (THV) 2. Implanting a second valve or valve-in-valve (ViV)

Conversion to surgery
In case of THV embolization ( Figure 1F) rule #1 is to keep the wire across the prosthesis, particularly in cases of balloon-expandable valve, that can tumble and obstruct the blood flow.
Here are our proposed management steps: If wire position was lost, the embolized valve must be re-crossed, using a Pigtail catheter to avoid crossing and getting stuck within stent struts.
Once a central position of the guidewire is achieved the native aortic valve must be recrossed and, holding the embolized valve in place with a snare, the second valve can be implanted as usual.
In case one cannot grasp the valve frame with the snare it is useful to get a Terumo glidewire (Terumo, Shibuya, Tokyo, Japan) across one strut of the THV, and try to catch the wire with the snare.
In certain scenarios, surgical conversion can be considered according to the patient and family's wishes and the patient's surgical risk. This is usually necessary in case of ventricular embolization.

| Vascular complications and aortic rupture
Peripheral vascular complications remain at 5%-8% in transfemoral (TF) TAVR, despite the relative low-profile sheaths of currently available devices, more accurate preprocedural planning and micropuncture access along with ultrasound or fluoroscopic-guided access and preclosure techniques.
Pelvic vascular injuries such as bleedings ( Figure 1C) and dissections causing flow-limiting lesions, or pseudoaneurysm are the most common vascular complications of TF-TAVR.
On the other hand, injuries of the great vessels (i.e., thoracic or abdominal aorta, subclavian artery) are rarer but can be catastrophic, needing surgical or endovascular bailout strategies but carries a poor prognosis. 14 In case of using radial artery as secondary arterial access to perform bailout strategies, 15 it is crucial before starting to know the equipment available on site, since the dimensions of the sheaths as well as the guidewires, catheters and stents lengths may not reach the target peripheral vessel!

| Bailout strategies for peripheral vascular injuries
The diagnosis of ileo-femoral dissection, disruption or pseudoaneurysm is suspected clinically and confirmed by fluoroscopy, typically by digital subtraction angiogram.
Cross-Over Balloon Technique from the contralateral common femoral artery could be performed over a "0.018" or "0.035" guidewire and with a 5Fr IMA (Internal mammary artery), UF (Universal flush) or JR (Judkins right) catheter. An appropriately sized balloon catheter inflated proximally to the lesion allows achieving temporary hemostasis while appropriate final treatment is planned.
In small, localized dissection a balloon dilatation for 15 min can be sufficient to achieve vascular sealing. Otherwise, a peripheral stent is required. Consider partial reversal of the heparinization effect to facilitate hemostasis. Peripheral self-expanding covered stentgrafts may be needed in case of vessel lacerations. Make sure to apply an oversizing of at least 15% to prevent endoleaks. A preventive crossover wire is a good option in case of complex femoral anatomies with high risk of periprocedural lesions.
In case of very challenging cross-over anatomies (tortuosity, calcification and steep bifurcation angle), the alternative is to perform a ipsilateral distal access puncturing the superficial femoral artery to place the stent retrogradely. In this case it is fundamental to puncture the distal access at a sufficient distance to allow easy and effective maneuvering.
Involving a vascular surgeon early or pre-emptively may avoid these potential complications and can be life-saving.

| Bailout strategies for thoraco-abdominal aorta injuries
This rare by devastating complication is suspected clinically by the rapid onset of profound hypotension, generally soon after valve deployment, or device's introducer insertion or removal.
At fluoroscopy, a huge extravasation of contrast medium or an evident intimal flap may appear. The first goal is to avoid exsanguination.
An occlusive balloon inflated just proximal to the rupture site may help buy time to provide further interventional treatments such endovascular aortic repair (EVAR) with available endografts.
Open surgery can also be an option, particularly dissection of the ascending aorta that may occur either after wire and catheters manipulations or after valve deployment ( Figure 1D).

| Acute coronary occlusion
Acute coronary obstruction after TAVR is a rare but potentially devasting complication, carrying as much as 50% of mortality. 16 The best way to prevent this life-threatening complication is an accurate preoperative evaluation of coronary obstruction risk. 17 In recent years, the development of the interventional technique called BASILICA 18 to intentionally split native or bioprosthetic aortic leaflets has led the achievement of good outcomes even when a high risk of occlusion is expected. Nonetheless, the technique is quite challenging and requires a proper learning curve. Also, commissural alignment of the THV is also necessary to avoid the commissural post obstructing the split portion of the leaflet after a successful BASILICA.
It is well-established that ViV procedures, especially those involving stentless bioprosthesis or stented bioprosthesis with externally mounted leaflets, low-coronary ostia (<10 mm from the aortic basal plane) and a shallow SoV and sino-tubular junction (STJ) present a four to sixfold increased risk of coronary obstruction. 19 Nevertheless, in native aortic valve anatomy this complication may occur in the presence of a tall and bulky leaflet facing the coronary ostium ( Figure 1E).
An accurate preprocedural evaluation, including a planning for adjunctive techniques for coronary protection such as prophylactic chimney snorkel 20 have led to a reduction of this complication. Once occurred, a prompt interventional management is mandatory to improve outcomes.

| Emergent cardio-pulmonary bypass (CPB) institution
Life-threatening TAVR complications causing refractory cardiogenic or hemorrhagic shock can be managed by expeditious institution of CPB as GENNARI ET AL.
| 2057 a bridge-to-decision with temporary cardio-respiratory support. 21 Both hybrid operating suites and catheterization laboratories performing structural heart procedures must be equipped to quickly setup extracorporeal membrane oxygenation (ECMO) support. An on-site perfusionist on call is mandatory to help operate the mechanical circulatory support equipment. Some Institutions have a full CPB machine running on stand-by, which can be used for support or surgical conversion.
We do not use ECMO systems unless there is a need for postoperative mechanical circulatory support. The fastest way to institute the mechanical support is using the primary femoral vascular access site as the default entry for cannula placement.
The arterial cannula should be advanced to the common iliac artery, Before the patient being transferred, securing the cannula by silk stitches on the skin and proper dressing is mandatory to avoid cannula dislodgment or removal.

| COMMENT
Although serious TAVR complications are quite rare in the current era, they still carry significant morbidity and mortality. Prevention remains the most important strategy but when a complication occurs, it is crucial to make a prompt diagnosis and treatment plan.
In the absence of international guidelines, each operator normally adopts "personal" protocols that may be not be standardized, leading some delay in the management even within the same Institution.

| CONCLUSION
Each specialized Center should institute and make easily accessible standardized emergency kits for the most common life-threatening conditions during TAVR that should be readily available in the cath-lab or hybrid operation room. It may improve the readiness of the team to treat the emergency situation and may help improve the outcome.