Ventricular force‐frequency relationships during biventricular or multisite pacing in congenital heart disease

Background: Traditional indices to evaluate biventricular (BiV) pacing are load dependent, fail to assess dynamic changes, and may not be appropriate in patients with congenital heart disease (CHD). We therefore measured the force‐frequency relationship (FFR) using tissue Doppler‐de‐ rived isovolumic acceleration (IVA) to assess the dynamic adaption of the myocardium and its vari‐ ability with different ventricular pacing strategies.
Methods: This was a prospective pilot study of pediatric and young adult CHD patients with biventricular or multisite pacing systems. Color‐coded myocardial velocities were recorded at the base of the systemic ventricular free wall. IVA was calculated at resting heart rate and with incremental pacing. FFR curves were obtained by plotting IVA against heart rate for different ventricular pacing strategies.
Results: Ten patients were included (mean: 22 ± 7 years). The FFR identified a best and worst ventricular pacing strategy for each patient, based on the AUC at baseline, submaximal, and peak heart rates (P < .001). However, there was no single best ventricular pacing strategy that was optimal for all patients. Additionally, the best ventricular pacing strategy often differed within the same patient at different heart rates.
Conclusion: This novel assessment demonstrates a wide variability in optimal ventricular pac‐ ing strategy. These inherent differences may play a role in the unpredictable clinical response to BiV pacing in CHD, and emphasizes an individualized approach. Furthermore, the optimal ventricular pacing varies with heart rate within individuals, suggesting that rate‐responsive ventricular pacing modulation may be required to optimize ventricular performance.     

Left bundle branch pacing from distal His‐bundle region by tricuspid valve annulus angiography

A 78‐year‐old man presenting with amaurosis was admitted to the outpatient clinic 1 week ago. His baseline electrocardiogram showed Mobitz type II atrioventricular block and right bundle branch block. The patient's heart rate from Holter was only 32 bpm and therefore the indication for pacemaker implantation.     

Persistent atrial standstill following the Cox‐maze III procedure: reversal with sustained atrial pacing

Atrial standstill is a rare disorder of cardiac rhythm that is characterized by total absence of electrical activity in one or both atria. We report herein the case of a patient with atrial fibrillation and symptomatic 4.0 s pauses who received a ventricular demand pacemaker. The patient later underwent mitral valve replacement with a pericardial tissue valve and the Cox‐maze III procedure for symptomatic mitral stenosis and atrial fibrillation. Following surgery, he developed atrial standstill and became pacemaker dependent. The pacemaker was later revised to an atrioventricular sequential pacemaker. Twelve hours after revision, atrioventricular sequential pacing was noted and mechanical function of the atria was confirmed by Doppler echocardiography.     

LV only pacing‐mediated electrical storm with cardiac resynchronization therapy managed by simultaneous biventricular pacing

Ventricular arrhythmia (VA) is a rare complication of cardiac resynchronization therapy (CRT). Little is known about ventricular proarrhythmia related to the pacing vector of CRT. This case report describes the elimination of ventricular arrythmia using biventricular pacing in a patient with VT‐storm related to LV only pacing as part of the AdaptivCRT algorithm (Medtronic Inc). Simultaneous biventricular pacing was effective in eliminating polymorphic ventricular tachycardia. Changing the pacing vector is a noninvasive treatment strategy that should be considered to manage VA due to CRT.