Andre Tay

Left Ventricular Mechanical Assist Devices and Cardiac Device Interactions: An Observational Case Series

Background: Nonpulsatile left ventricular assist devices (LVADs) are increasingly used for treatment of refractory heart failure. A majority of such patients have implanted cardiac devices, namely implantable cardioverter‐defibrillators (ICDs) or cardiac resynchronization therapy‐pacemaker (CRT‐P) or cardiac resynchronization therapy‐defibrillator (CRT‐D) devices. However, potential interactions between LVADs and cardiac devices in this category of patients remain unknown.

Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

OBJECTIVES The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). BACKGROUND Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. METHODS Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. RESULTS Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events. CONCLUSIONS Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate.

Impact of Implantable Cardioverter Defibrillators on Survival of Patients with Centrifugal Left Ventricular Assist Devices

Both implantable cardioverter defibrillators (ICDs) and left ventricular assist devices (LVADs) have a positive impact on survival in the heart failure population. We sought to determine whether these positive effects on survival are additive or whether LVAD therapy supersedes ICD therapy.

Accelerated graft dysfunction in heart transplant patients with persistent atrioventricular conduction block

AIMS Bradyarrhythmia following heart transplantation is common-∼7.5-24% of patients require permanent pacemaker (PPM) implantation. While overall mortality is similar to their non-paced counterparts, the effects of chronic right ventricular pacing (CRVP) in heart transplant patients have not been studied. We aim to examine the effects of CRVP on heart failure and mortality in heart transplant patients. METHODS AND RESULTS Records of heart transplant recipients requiring PPM at St Vincents Hospital, Sydney, Australia between January 1990 and January 2015 were examined. Patients without a right ventricular (RV) pacing lead or a follow-up time of <1 year were excluded. Patients with pre-existing abnormal left ventricular function (<50%) were analysed separately. Patients were grouped by pacing dependence (100% pacing dependent vs. non-pacing dependent). The primary endpoint was clinical or echocardiographic heart failure (<35%) in the first 5 years post-PPM. Thirty-three of 709 heart transplant recipients were studied. Two patients had complete RV pacing dependence, and the remaining 31 patients had varying degrees of pacing requirement, with an underlying ventricular escape rhythm. The primary endpoint occurred significantly more in the pacing-dependent group; 2 (100%) compared with 2 (6%) of the non pacing dependent group (P < 0.0001 by log-rank analysis, HR = 24.58). Non-pacing-dependent patients had reversible causes for heart failure, unrelated to pacing. In comparison, there was no other cause of heart failure in the pacing-dependent group. CONCLUSIONS Permanent atrioventricular block is rare in the heart transplant population. We have demonstrated CRVP as a potential cause of accelerated graft failure in pacing-dependent heart transplant patients.

Metastatic Merkel cell carcinoma of the heart

A 76-year-old-man with ischaemic cardiomyopathy and a cardiac resynchronization therapy defibrillator presented after a witnessed collapse. The patient denied any cardiorespiratory symptoms, but reported recent lethargy and weight loss. Two years earlier, he was diagnosed with Merkel cell carcinoma of the left neck, successfully treated with modified radical neck dissection and adjuvant radiotherapy. Cardiac resynchronization therapy defibrillator …

Managed Ventricular Pacing algorithm during brady- and tachyarrhythmia

ase history 29-year-old man with idiopathic dilated cardiomyopathy ejection fraction 20%) and a dual-chamber implantable ardioverter-defibrillator (ICD; Medtronic Intrinsic, edtronic Inc., Minneapolis, MN) was transferred to our nstitution for assessment for heart transplantation due to radual symptomatic deterioration over the last 3 months. onitoring during hospitalization demonstrated a regular radycardic broad complex rhythm with asynchronous pacng artifact (Figure 1), which prompted an interrogation of he ICD. The programmed parameters are shown in Table 1. nterrogation of the ICD also revealed an episode of montored tachyarrhythmia logged 5 months before the hospital ransfer (Figure 2). What is the cause of (1) the asynchroous pacing and (2) the intermittent atrial refractory events nd atrial pacing during the monitored tachyarrhythmia?

Complete heart block

This patient was admitted 3-months post-orthotopic heart transplantation (biatrial anastomosis) with the following electrocardiogram (ECG). The anastomosis resulted in electrical …