Ventricular unloading causes prolongation of the QT interval and induces ventricular arrhythmias in rat hearts

Introduction

Ventricular unloading during prolonged bed rest, mechanical circulatory support or microgravity has repeatedly been linked to potentially life-threatening arrhythmias. It is unresolved, whether this arrhythmic phenotype is caused by the reduction in cardiac workload or rather by underlying diseases or external stimuli. We hypothesized that the reduction in cardiac workload alone is sufficient to impair ventricular repolarization and to induce arrhythmias in hearts.

Methods

Rat hearts were unloaded using the heterotopic heart transplantation. The ECG of unloaded and of control hearts were telemetrically recorded over 56 days resulting in >5 × 106 cardiac cycles in each heart. Long-term electrical remodeling was analyzed using a novel semi-automatic arrhythmia detection algorithm.

Results

56 days of unloading reduced left ventricular weight by approximately 50%. While unloading did not affect average HRs, it markedly prolonged the QT interval by approximately 66% and induced a median tenfold increase in the incidence of ventricular arrhythmias in comparison to control hearts.

Conclusion

The current study provides direct evidence that the previously reported hypertrophic phenotype of repolarization during cardiac unloading translates into an impaired ventricular repolarization and ventricular arrhythmias in vivo. This supports the concept that the reduction in cardiac workload is a causal driver of the development of arrhythmias during ventricular unloading.

Case Report: Sustained ventricular arrhythmia in a child supported by a Berlin heart EXCOR ventricular assist device

Mechanical circulatory support is an established therapy to support failing hearts as a bridge to transplantation. Although tolerated overall, arrhythmias may occur after ventricular assist device implantation and can complicate patient management. We report on an infant with dilated cardiomyopathy who developed ventricular tachycardia followed by recalcitrant ventricular fibrillation, refractory to comprehensive medical therapy post Berlin Heart EXCOR® (BHE) implant.

Impact of Ventricular Arrhythmia on LVAD Implantation Admission Outcomes

INTRODUCTION

Ventricular arrhythmias (VAs) are common after left ventricular assist device (LVAD) implantation though data are mixed on whether these events have an impact on mortality.

METHODS

The National Inpatient Sample (NIS) database from 2002 - 2019 was queried for LVAD implantation admissions. Secondary ICD codes were analyzed to assess for the occurrence of VAs during this admission. Propensity score matching (PSM) was used to control for confounding variables between those with versus without VAs.

RESULTS

The NIS database from 2002 - 2019 contained 43,936 admissions with LVAD implantation. VAs occurred in 19,985 (45.4%) patients. After PSM, the study cohort consisted of 39,989 patients, 19,985 (50.0%) of which had a secondary diagnosis of VA during the admission. When compared to those without VA, those with VA were at no higher risk for in-hospital mortality (adjusted odds ratio 1.011, 99.9% CI 0.956 - 1.069, p = 0.699). Those with a VA were at higher risk for cardiogenic shock and requiring mechanical ventilation, tracheostomy, and percutaneous endoscopic gastrostomy placement. Patients with a VA were also at lower risk for device thrombosis. Conversely, the VA group was at no higher risk for stroke. In comparing trends from 2002 to 2019, the incidence of VAs has increased, while the mortality rate of those with and without VAs has decreased during this same period.

CONCLUSION

In this retrospective study of the NIS database, VAs were common (45.4%) during the LVAD implantation admission. However, the occurrence of VAs during the implantation admission did not alter in-hospital mortality. More longitudinal studies are required to assess the long-term impact of VAs on mortality. In comparing trends from 2002 - 2019, the incidence of VAs has increased, while the mortality rate of those with and without VAs has decreased.

Successful recovery from refractory hypoxia due to right-to-left shunting associated with iatrogenic atrial septal defect after catheter ablation in a patient with a left-ventricular assist device: a case report

Background

Catheter ablation (CA) has been reported to be an effective therapeutic option for ventricular arrhythmias, even in patients with a left-ventricular assist device (LVAD). However, the issues of right-to-left shunting due to iatrogenic atrial septal defect (iASD) associated with procedures for CA have not been well documented. We describe a rare case of refractory hypoxia associated with right-to-left shunting via iASD after CA through the transseptal approach in an LVAD patient.

Case summary

A 52-year-old Asian man with a continuous-flow implantable LVAD and progressive right ventricular (RV) dysfunction was admitted because of refractory ventricular tachycardia (VT) and subsequent right heart failure. Since VT could not be controlled by intravenous administration of multiple antiarrhythmic drugs, VT ablation via the transseptal approach was performed. Ventricular tachycardia was terminated to the sinus rhythm after VT ablation; however, hypoxia associated with significant right-to-left shunting across the iASD was detected. Intensive medical management, such as an adjusted mechanical ventilator to increase pulmonary vascular compliance and adjustment of LVAD pump speed, as well as the use of intravenous inotropes to support impaired RV function successfully stabilized the haemodynamic and improved hypoxia for the disappearance of right-to-left shunting. Echocardiography at 7 months after CA showed that the significant iASD and right-to-left shunting had disappeared.

Discussion

The evaluation of RV function prior to VT ablation via the transseptal approach is important in the postoperative management of patients with LVAD, because RV dysfunction may cause refractory hypoxia due to iASD.

HeartMate 3: new challenges in ventricular tachycardia ablation

AIM

To describe clinical characteristics, procedural details, specific challenges, and outcomes in patients with HeartMate3™ (HM3), a left ventricular assist device system with a magnetically levitated pump, undergoing ventricular tachycardia ablation (VTA).

METHODS AND RESULTS

Data were collected from patients with an HM3 system who underwent VTA in seven tertiary centres. Data included baseline patient characteristics, procedural data, mortality, and arrhythmia-free survival. The study cohort included 19 patients with cardiomyopathy presenting with ventricular tachycardia (VT) (53% with VT storm). Ventricular tachycardias were induced in 89% of patients and a total of 41 VTs were observed. Severe electromagnetic interference was present on the surface electrocardiogram. Hence, VT localization required analysis of intra-cardiac signals or the use of filter in the 40-20 Hz range. The large house pump HM3 design obscured the cannula inflow and therefore multi imaging modalities were necessary to avoid catheter entrapment in the cannula. A total of 32 VTs were mapped and were successfully ablated (31% to the anterior wall, 38% to the septum and only 9% to the inflow cannula region). Non-inducibility of any VT was reached in 11 patients (58%). Over a follow-up of 429 (interquartile range 101-692) days, 5 (26%) patients underwent a redo VT ablation due to recurrent VTA and 2 (11%) patients died.

CONCLUSIONS

Ventricular tachycardia ablation in patients with HM3 is feasible and safe when done in the appropriate setup. Long-term arrhythmia-free survival is acceptable but not well predicted by non-inducibility at the end of the procedure.

Mapping and Ablation of Ventricle Arrhythmia in Patients with Left Ventricular Assist Devices

Ventricular arrhythmias (VA) constitute well-known problems in patients with left ventricular assist devices (LVADs), with incidence ranging from 18% to as high as 52%. Catheter ablation has become a common therapeutic intervention to treat drug-refractory VA, particularly with the increase and more widespread use of durable LVADs to bridge patients to transplantation or as destination therapy. In this article, we focus on etiology, mechanisms, periprocedural management, and mapping and ablation techniques in patients with LVADs and VA.

Early Ventricular Arrhythmias After LVAD Implantation Is the Strongest Predictor of 30-Day Post-Operative Mortality

OBJECTIVES

This study aimed to evaluate incidence, clinical significance, and predictors of early ventricular arrhythmias (VAs) in left ventricular assist device (LVAD) recipients.

BACKGROUND

LVAD implantation is increasingly used in patients with end-stage heart failure. Early VAs may occur during the 30-day post-operative period, but many questions remain unanswered regarding their incidence and clinical impact.

METHODS

This observational study was conducted in 19 centers between 2006 and 2016. Early VAs were defined as sustained ventricular tachycardia and/or ventricular fibrillation occurring <30 days post-LVAD implantation and requiring appropriate implantable cardioverter-defibrillator therapy, external electrical shock, or medical therapy.

RESULTS

A total of 652 patients (median age: 59.8 years; left ventricular ejection fraction: 20.7 ± 7.4%; HeartMate 2: 72.8%; HeartWare: 19.5%; Jarvik 2000: 7.7%) were included in the analysis. Early VAs occurred in 162 patients (24.8%), most frequently during the first week after LVAD implantation. Multivariable analysis identified history of VAs prior to LVAD and any combined surgery with LVAD as 2 predictors of early VAs. The occurrence of early VAs with electrical storm was the strongest predictor of 30-day post-operative mortality, associated with a 7-fold increase of 30-day mortality. However, in patients discharged alive from hospital, occurrence of early VAs did not influence long-term survival.

CONCLUSIONS

Early VAs are common after LVAD implantation and increase 30-day post-operative mortality, without affecting long-term survival. Further studies will be needed to analyze whether pre- or pre-operative ablation of VAs may improve post-operative outcomes. (Determination of Risk Factors of Ventricular Arrhythmias After Implantation of Continuous Flow Left Ventricular Assist Device With Continuous Flow Left Ventricular Assist Device [ASSIST-ICD]; NCT02873169).

[Ventricular Fibrillation in a Patient with Implanted Left Ventricular Assist Device Heart Mate II]

In this article we present a clinical case of a 46-year-old man, who developed ventricular fibrillation at the background of implanted left ventricular assist device (LVAD) Heart Mate II because of dilated cardiomyopathy with biventricular chronic heart failure. Ventricular fibrillation required electrical and medical defibrillation with further treatment in the intensive care unit.

Implantable cardioverter-defibrillators and survival in advanced heart failure patients with continuous-flow left ventricular assist devices: a systematic review and meta-analysis

Aims

Implantable cardioverter-defibrillators (ICDs) implantation in heart failure (HF) patients with reduced ejection fraction improves survival by reducing mortality secondary to arrhythmic events. Whether advanced HF patients treated with continuous-flow left ventricular assist devices (CF-LVADs) derive similar benefit is controversial.

Methods and results

We searched PubMed, Cochrane Central Register of Controlled Trials, Embase, and Scopus from inception through November 2018 for studies examining the association between ICD implantation and all-cause mortality in patients with advanced HF and CF-LVADs. Analyses were performed using a random-effects model. Hazard ratios (HRs) were calculated with 95% confidence intervals (CIs). Heterogeneity and publication bias were formally assessed, using I2 and funnel plots, respectively. Eight observational studies with a total of 6416 patients (ICD group = 3450, no ICD group = 2966) met inclusion criteria. The majority of patients (84.6%) came from the two largest observational studies. There was no difference in mortality in the ICD and no ICD groups (HR 0.96, 95% CI 0.73–1.27, P = 0.79, I2 = 42%), and ICD implantation post-CF-LVAD was not associated with an improvement in mortality (HR 0.87, 95% CI 0.48–1.57, P = 0.64, I2 = 0%). Additionally, there was no significant difference in the likelihood of transplantation (HR 1.10, 95% CI 0.93–1.30, P = 0.28, I2 = 26%) or non-mortality adverse events between the two groups.

Conclusion

Implantable cardioverter-defibrillator use was not associated with improved survival in advanced HF patients with CF-LVADs. These findings underscore the need to formally study the efficacy of ICDs in this population in a dedicated randomized controlled study.

Hemodynamic deterioration precedes onset of ventricular tachyarrhythmia after Heartmate II implantation

Background

Early postoperative ventricular tachyarrhythmia (PoVT) after left ventricular assist device (LVAD) implantation are common and associated with higher mortality-rates. At present, there is no data on initiation of these PoVT and the role of alterations in cardiac hemodynamics.

Case Presentation

A LVAD was implanted in a patient with end-stage heart failure due to a ischemic cardiomyopathy. Alterations in cardiac rhythm and hemodynamics preceding PoVT-episodes during the first five postoperative days were examined by using continuous recordings of cardiac rhythm and various hemodynamic parameters. All PoVT (N=120) were monomorphic, most often preceded by short-long-short-sequences or regular SR and initiated by ventricular runs. Prior to PoVT, mean arterial pressure decreased; heart rate and ST-segments deviations increased.

Conclusions

PoVT are caused by different underlying electrophysiological mechanisms. Yet, they are all monomorphic and preceded by hemodynamic deterioration due to myocardial ischemia.

B-Type Natriuretic Peptide Levels Predict Ventricular Arrhythmia Post Left Ventricular Assist Device Implantation

B-type natriuretic peptide (BNP) levels have been shown to predict ventricular arrhythmia (VA) and sudden death in patients with heart failure. We sought to determine whether BNP levels before left ventricular assist device (LVAD) implantation can predict VA post LVAD implantation in advanced heart failure patients. We conducted a retrospective study consisting of patients who underwent LVAD implantation in our institution during the period of May 2009-March 2013. The study was limited to patients receiving a HeartMate II or HeartWare LVAD. Acute myocardial infarction patients were excluded. We compared between the patients who developed VA within 15 days post LVAD implantation to the patients without VA. A total of 85 patients underwent LVAD implantation during the study period. Eleven patients were excluded (five acute MI, four without BNP measurements, and two discharged earlier than 13 days post LVAD implantation). The incidence of VA was 31%, with 91% ventricular tachycardia (VT) and 9% ventricular fibrillation. BNP remained the single most powerful predictor of VA even after adjustment for other borderline significant factors in a multivariate logistic regression model (P < 0.05). BNP levels are a strong predictor of VA post LVAD implantation, surpassing previously described risk factors such as age and VT in the past.

Ventricular arrhythmias in patients with heart failure secondary to reduced ejection fraction: a current perspective

PURPOSE OF REVIEW

To review the management of ventricular arrhythmias in patients with heart failure secondary to reduced ejection fraction (HFrEF).

RECENT FINDINGS

Recurrent ventricular arrhythmias and automatic implantable cardioverter defibrillator (AICD) shocks are responsible for significant mortality and morbidity in patients with HFrEF. Antiarrhythmic drugs and catheter ablation are the main treatment options. Frequent premature ventricular contractions (PVCs; >10,000-20,000/24-h period) are being recognized as a cause of cardiomyopathy and suboptimal response to cardiac resynchronization therapy (CRT). Patients with ventricular assist devices (VADs) have frequent ventricular tachyarrhythmias resulting in increased morbidity and mortality. Such patients may need continuation of active ICD therapy and adjunctive catheter ablation.

SUMMARY

There is a pressing need to develop new antiarrhythmic drugs to treat patients with recurrent AICD shocks. The effectiveness of catheter ablation as first-line therapy for preventing ventricular arrhythmias and recurrent AICD shocks needs to be directly compared with amiodarone. Ventricular tachyarrhythmias are common in CRT patients and patients with VADs. Frequent PVCs may result in a reversible form of HFrEF.

Catheter ablation for premature ventricular contractions and ventricular tachycardia in patients with heart failure

Ventricular arrhythmias (VA) are a significant contributor to morbidity and mortality in patients with heart failure (HF). Implantable cardioverter defibrillators are effective in reducing mortality, but do not prevent arrhythmia recurrence. There is increasing recognition that frequent premature ventricular contractions or repetitive ventricular tachycardia may also lead to new onset ventricular dysfunction or deterioration of ventricular function in patients with pre-existing HF. Suppression of the arrhythmia may lead to recovery of ventricular function. Catheter ablation has emerged as a safe and effective treatment option for reducing arrhythmia recurrence and for suppression of PVCs but its efficacy is governed by the nature of the arrhythmias, the underlying HF substrate and the accessibility of the arrhythmia substrates to ablation.

Current indications for heart transplantation and left ventricular assist device: a practical point of view

Heart transplantation (HTx) is considered the "gold standard" therapy of refractory heart failure (HF), but it is accessible only to few patients because of the paucity of suitable heart donors. On the other hand, left ventricular assist devices (LVADs) have proven to be effective in improving survival and quality of life in patients with refractory HF. The challenge encountered by multidisciplinary teams in dealing with advanced HF lies in identifying patients who could benefit more from HTx as compared to LVAD implantation and the appropriate timing. The decision-making is based on clinical parameters, imaging-based data and risk scores. Current outcome of HF patients supported by LVAD (2-year survival around 70%) is rapidly improving and leads the way to a new therapeutic strategy. Patients who have a low likelihood to gain access to the heart graft pool could benefit more from LVAD implantation (defined as bridge to transplantation indication) than from remaining on HTx waiting list with the likely risk of clinical deterioration or removal from the list because patients are no longer suitable for transplantation. LVAD has also demonstrated to be effective in patients who are not considered eligible candidates for HTx with a destination therapy indication. HTx should be reserved to those patients for whom the maximum clinical benefit can be expected, such as young patients with no comorbidities. Here we discuss the current listing criteria for HTx and indications to implant of LVAD for patients with refractory acute and chronic HF based on the guidelines and the practical experience of our center.

Effect of counter-pulsation control of a pulsatile left ventricular assist device on working load variations of the native heart

Background

When using a pulsatile left ventricular assist device (LVAD), it is important to reduce the cardiac load variations of the native heart because severe cardiac load variations can induce ventricular arrhythmia. In this study, we investigated the effect of counter-pulsation control of the LVAD on the reduction of cardiac load variation.

Methods

A ventricular electrocardiogram-based counter-pulsation control algorithm for a LVAD was implemented, and the effects of counter-pulsation control of the LVAD on the reduction of the working load variations of the left ventricle were determined in three animal experiments.

Results

Deviations of the working load of the left ventricle were reduced by 51.3%, 67.9%, and 71.5% in each case, and the beat-to-beat variation rates in the working load were reduced by 84.8%, 82.7%, and 88.2% in each ease after counter-pulsation control. There were 3 to 12 premature ventricle contractions (PVCs) before counter-pulsation control, but no PVCs were observed during counter-pulsation control.

Conclusions

Counter-pulsation control of the pulsatile LVAD can reduce severe cardiac load variations, but the average working load is not markedly affected by application of counter-pulsation control because it is also influenced by temporary cardiac outflow variations. We believe that counter-pulsation control of the LVAD can improve the long-term safety of heart failure patients equipped with LVADs.