Our patient had an AV interval
Our patient had an AV interval of approximately 100ms, reflecting the sensing of low atrial activity. The upper rate in the VVT mode is usually factory set and not programmable. However, it can be modified by programming the ventricular refractory period if necessary. This SGX523 had its upper rate set at 140 beats per minute. By reprogramming this to the longest refractory period setting of 475ms, the upper limit was set to 126 beats per minute.
The P-triggered VVT mode is dependent on appropriate sensing of the P wave. Fluctuations in P wave amplitude, as seen in Fig. 3C, or during atrial fibrillation might result in undersensing of the P wave. In this scenario, triggering by the R wave ensues if its amplitude is adequate. If the small R wave causes undersensing or if no R wave occurs, pacing will be at a low rate interval. As with the DDD mode, VVT may not be suitable in patients with frequent atrial tachycardia. It is not clear if this mode of AV synchrony can offer better hemodynamic effects.
Conflict of interest
Introduction Recently, the need for a cardiovascular implantable electronic device (CIED) for lead removal in patients has increased due to several factors, such as lead failure, infection, lead–lead interactions, venous stenosis or thrombosis, chronic pain at the device- or lead-insertion site, life-threatening arrhythmias secondary to retained leads, and the need to upgrade to a new technology [1,2]. The 2 major drawbacks of lead removal are traction to the tip of the lead and problems dissecting the fibrotic attachments of the lead from the surrounding tissues and vessel walls . Various extraction devices for traction and dissection are used worldwide, with several of these devices being available in Japan. In this report, we present findings using a new tool for dissection in transvenous pacing lead extraction.
Discussion The keys to a successful CIED lead removal were traction, dissection, and complete retrieval through the implant vein, without injury of the venous system and the myocardium. High success and low complication rates were achieved by avoiding the use of excessive force or powered sheaths to overcome tight binding sites . This new tool is one of the mechanical sheaths used for blunt dissection, but unlike a rotating threaded tip sheath [4–6], electrosurgical sheath , and a laser sheath , it cannot be used to perform sharp dissection.
Conflict of interest
Introduction The occurrence of bundle branch block during supraventricular tachycardia may aid in the differential diagnosis of the mechanism of supraventricular tachycardia. The phenomenon of a 2:1 bundle branch block is reported during atrioventricular (AV) nodal reentrant tachycardia, sinus tachycardia, atrial fibrillation, and atrial flutter [1–5]. A 2:1 bundle branch block is attributed to first- and second-degree bundle branch block, linking, electrical alternans, aberrancy, or supernormal conduction. However, the same phenomenon has not been reported in AV reentrant tachycardia. In this report, we present the case of AV reentrant tachycardia with a 2:1 right bundle branch block.
Case report The cardiac electrophysiologic study was performed after obtaining informed consent from the patient; the findings were as follows: sinus cycle length, 1100ms; atrial-His (AH) interval, 95ms; and His-ventricular (HV) interval, 50ms. Tachycardia with a cycle length of 450ms was reproducibly induced by atrial extrastimulus or decremental pacing (Fig. 1). A 2:1 right bundle branch block (RBBB) pattern and a 1:1 ventroculoatrial (VA) relationship were observed. The P wave was positive in the inferior leads and negative in V1, suggesting an anteroseptal or a right anterior accessory pathway. Intracardiac tracing (Fig. 2) showed (1) tachycardia with an alternating RBBB; (2) a normal HV interval; (3) the earliest retrograde atrial activation recorded in the His bundle catheter; (4) prolongation of the VA interval from 105 to 130ms with RBBB development; and (5) no change in R–R interval secondary to reciprocal shortening of the AH interval immediately after VA prolongation.