Shortness of breath and palpitations in an elderly man: Bad device behavior or malfunction?

70‐year‐old male with sinus node dysfunction (SND) and paroxysmal atrial fibrillation presents with shortness of breath and palpitations. Presenting EKG shows AF with rapid ventricular rates requiring direct current cardioversion (DCCV). Post‐DCCV EKG shows sinus rhythm with competing ventricular pacing. Device interrogation demonstrates the patient's generator at the elective replacement indicator (ERI) and has been forced to VVI 65 bpm causing dyssynchronous ventricular pacing and inducing AF. This case highlights the importance of close device follow up with timely PPM generator change prior to ERI, especially in patients with Medtronic Adapta devices, to avoid unnecessary dyssynchronous ventricular pacing. In addition, device manufacturers should focus on maintaining AV synchrony in pacemakers when they reach ERI.


| C A S E
A 70-year-old male presents with shortness of breath and palpitations. His history is remarkable for atrial fibrillation (AF) status postmultiple ablations and direct-current cardioversions (DCCV) as well as sinus node dysfunction (SND) status postpermanent pacemaker (PPM) implant 12 years ago. Several days prior to presentation, he initially felt worsening shortness of breath and a day later developed severe palpitations. Upon admission, he was found to be in AF with rapid ventricular rate. He underwent successful DCCV with resultant ECG as shown in Figure 1. Unfortunately, the patient continued to experience dyspnea despite being free of palpitations. What is the interpretation of the ECG? Does the patient have a single or dual chamber permanent pacemaker (PPM)? What clues on the ECG allude to a problem with the PPM that requires fixing?

| D ISCUSS I ON
A step-by-step analysis of the ECG, as well as basic knowledge of PPM programming, is required to make the correct diagnosis. The ECG shows normal sinus rhythm at 68 bpm with competing ventricular demand pacing at 65 bpm. Scanning from left to right, the 1st, 2nd, 3rd, 4th, 5th, 8th, and 11th complexes are fully ventricular paced (pacing spike followed by a wide QRS complex). The 6th and 9th complexes are pseudofused (the pacemaker has already committed to pacing based on the set timing cycle, as seen by the pacing spike, despite native conduction resulting in a narrow QRS complex). The 7th complex is a result of a premature atrial contraction (PAC) (P wave can be seen just prior to the preceding T wave in the lead II rhythm strip). And finally, the 10th complex is a natively conducted sinus beat. With each QRS complex identified, we can now discuss whether this a single or dual chamber PPM. To do this, we must first determine if the native atrial and ventricular activ- is activated 3 months prior to ERI and does not change any device programming. 2 In addition, if the generator is allowed to reach ERI and automatically switches to VVI 65 bpm, reprogramming can be performed, however, the generator will reach EOL at a faster rate.
Nonetheless, the impact of this feature on a patient's wellbeing can be quite troublesome leading to avoidable symptoms and unnecessary interventions, such as coronary angiograms and DCCV, as well as an overall increased cost to the healthcare system. When the generator is forced into a VVI 65 bpm mode at ERI, the pacemaker does not synchronously pace and leads to a profound version of pacemaker syndrome, causing symptoms such as shortness of breath, as occurred in our patient, and potentially chest pain.
In addition, high ventricular pacing percentages, specifically right ventricular septal and apical pacing, have been shown to be associated with AF. 4  In addition, device manufacturers should focus on maintaining AV synchrony in pacemakers when they reach ERI.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest for this article.