His-Purkinje system longitudinal dissociation: From bench to bedside. A case of output-dependent fascicular capture.

INTRODUCTION: Histological studies reported that the His bundle (HB) is partitioned into narrow cords by collagen running in its long axis, providing the anatomical setting necessary for its longitudinal dissociation. Further confirmations came from the demonstration that direct HB pacing normalizes the QRS axis and duration in subjects with proximal HB lesions causing bundle branch block. However, there is no evidence of the possibility of selective HB partitions pacing destined to the composition of branches and fascicles. METHODS AND RESULTS: We describe a case of intra-Hisian left bundle branch block in which permanent distal HB pacing corrects left ventricular delay and produces different QRS morphology at different voltage outputs, as an expression of different selective HB compartments recruitment. CONCLUSION: This case would strengthen the limited data in the literature about HB longitudinal dissociation.

Interatrial conduction time from electrograms of cardiac resynchronization therapy devices with left ventricular sensing.

BACKGROUND: The interatrial conduction time (IACT) is relevant for atrioventricular delay optimization in cardiac resynchronization therapy (CRT) devices. However, this information cannot be easily used as it requires invasive measurements. We tested whether electrical activation of left atrium (LA) could be detected in CRT devices with left ventricular (LV) sensing and used to estimate IACT. METHODS: The presence of LA activation on LV channel was evaluated in consecutive patients implanted with CRT and quadripolar LV leads whose sensing was temporarily set in the most proximal polarity (Ring LV4-housing). Estimates of IACT during sinus rhythm and atrial pacing were measured and compared with the values obtained with invasive catheterization of coronary sinus. RESULTS: Among six patients (50% female; mean age 73.3 ± 4.9 years) included in the analysis, four (66%) had a visible LA signal on the LV channel. The mean IACT measured with device electrograms was 71 ± 8 ms and 133 ± 15 ms during sinus rhythm and atrial pacing, respectively. These values were equivalent to the measurements obtained during invasive catheterization. Both patients without evidence of LA activation had an LV lead with a short total interelectrodes distance (46 mm) resulting in a significant anatomical distance between Ring LV4 and LA. CONCLUSIONS: In CRT devices with left ventricular sensing, LA signal could be detected and used to estimate IACT especially if long-spaced electrodes are used.

His bundle pacing: Clinical consequences of unnecessary right ventricle backup pacing.

As a backup lead in right ventricle (RV) is often used in His-bundle pacing (HBP) implants, in sinus rhythm patients the His lead is connected to the left ventricular (LV) port of a CRT device. In current devices, the backup pacing will be delivered 100% of time due to cross-channel ventricular refractory periods. Beyond an impact on battery, unnecessary RV pacing could find excitable tissue and capture a portion of the myocardium tissue potentially reducing the benefits of physiological HBP as shown in this case report where the switch from biventricular to LV-only pacing improved acute and 2-month echocardiography parameters.

Closed loop stimulation with His bundle lead placement.

Closed-loop stimulation (CLS; BIOTRONIK SE & Co. KG, Berlin, Germany) is a rate-responsive algorithm that analyzes intracardiac impedance trends using a standard lead placed in the right ventricle. It is unknown whether CLS could perform adequately with His bundle (HB) lead placement, as contractility dynamics may be attenuated in this region compared to the right ventricle apex.We performed hand-grip, mental, and bicycle exercise tests in a patient with brady atrial fibrillation and permanent HB pacing. The CLS algorithm responded with an appropriate heart rate to mental and physical tests. Learning objective: A combination of permanent His bundle and closed-loop stimulation-driven pacing may be a valid and physiological option for atrial fibrillation patients with chronotropic incompetence.

Electrical storm in a patient with COVID-19 treated with hydroxychloroquine: A case report.

Hydroxychloroquine (HCQ) is a widely used drug to treat patients with coronavirus disease 19 (COVID-19). Although evidence of its efficacy and safety remains limited and controversial, both cardiac and non-cardiac adverse events are known to be associated with its use. To our knowledge, electrical storm in patients with COVID-19, or in any case treated with HCQ, has not been reported. We report the case of a 78-year-old male with an implantable cardiac resynchronization defibrillator (CRT-D) and a non-severe form of COVID-19. After a few days of home therapy with HCQ, an electrical storm was revealed that was associated with an increase in QTc. Following admission to the intensive care unit, HCQ was discontinued and progressive reduction of the QTc with electrical stabilization was observed. This clinical case highlights the potential risk of arrythmia associated with the use of HCQ and stresses the need for close electrocardiographic monitoring, especially in patients with established heart disease.

Is dedicated implantation tool set really needed for permanent His bundle pacing?

This case describes the feasibility of permanent His bundle pacing (HBP) with a standard bipolar lead positioned through cephalic access without a dedicated delivery sheath. The use of a stylet pre-shaped on an echocardiographic reference allowed a successful procedure without specific technical difficulties. This "simplified" approach may provide some advantages with respect to the only commercially available system.

The effectiveness of remote monitoring of elderly patients after hospitalisation for heart failure: The renewing health European project.

Background: The effectiveness of remote monitoring (RM) in the management of the elderly after hospitalisation for heart failure (HF) is uncertain. Methods and results: Randomized trial (2:1 design) comparing RM with usual care (UC) in patients >65 years old, hospitalised in the previous 3 months for HF with left ventricular ejection fraction <40% or >40% plus BNP > 400 (or NT-proBNP >1500); the primary end-point (PE) was the combined 12-month incidence of death by any cause or at least one hospital readmission for HF. Overall, 229 and 110 pts were enrolled in the RM and UC group, respectively; in the intention-to-treat analysis, the PE was reached in 101 (44.1%) and 51 (46.4%) patients in the RM and UC group respectively (p = 0.78), with no difference in mortality (24.0% vs 21.8%, p = 0.097) or in the proportion of patients with at least one rehospitalisation for HF (34.5% vs 39.1%, p = 0.48). Quality of life, secondary end-point measured by SF36v2 scores, was significantly improved in the RM group, both in physical (2.63 score difference, p < 0.0001) and mental (1.69 score difference, p = 0.04) components. In the on-treatment analysis comparing 190 patients that ultimately received RM with the 149 remaining patients, the primary end-point was reached in 40.0% vs 51.0% (p = 0.055), respectively. Conclusion: In the intention-to-treat analysis, during the 12-month follow up of elderly patients hospitalised for HF, remote monitoring had no impact on the primary end-point but it significantly improved patients' quality of life. In the on-treatment analysis a trend for improving the PE was observed in the RM group.