Right ventricular failure in patients with left ventricular assist devices

Right ventricular (RV) failure that develops following LVAD placement is an important and challenging complication that occurs in approximately 15-25% of LVAD patients. Thus, a thorough evaluation that identifies pre-operative clinical predictors of RV failure is crucial to aid in the appropriate treatment and prognostication. Following LVAD implant, three major physiologic changes invariably occur that will influence RV function: an increase in RV preload, a decrease in RV afterload, and an alteration in RV contractility. Management strategies exist to minimize the likelihood and severity of RV failure post-LVAD. Further studies are needed that also focus on intermediate and late post-LVAD RV failure.     

Use of implantable cardioverter defibrillators in patients with left ventricular assist devices

Patients with left ventricular assist devices (LVADs) are at high risk of sustained ventricular arrhythmias, but these may be remarkably well tolerated and the association with sudden death is unclear. Many patients who receive an LVAD already have an implantable cardioverter defibrillator (ICD). While it is standard practice to reactivate a previously implanted ICD in an LVAD recipient, this should include discussion of the revised risks and benefits of ICD therapy following LVAD implantation. In particular, patients should be warned that they might receive a significant number of ICD shocks that may not be life saving. When ICDs are reactivated, device programming should minimize the risk of repeated shocks for non-sustained or well-tolerated ventricular arrhythmias. Implantation of a primary prevention ICD after implantation of an LVAD is not supported by current evidence, poses potential risks, and should be the subject of a clinical trial before it becomes standard practice.     

Arrhythmias after left ventricular assist device implantation: Incidence and management

The use of mechanical circulatory support has become an increasingly common practice in patients with heart failure, whether used as bridge to transplantation or as destination therapy. The last couple of decades has seen a drastic change in the functioning of the left ventricular assist devices (LVAD), changing from the first generation devices running on pulsatile flow to the current continuous flow devices. Atrial and ventricular arrhythmias are common among heart failure patients, and though the systematic circulation is well supported in patients on mechanical circulatory support, these arrhythmias can still be the cause of detrimental symptoms and lead to potentially fatal outcomes. Several studies have shown that mortality rates in LVAD recipients secondary to lethal arrhythmias are uncommon, and newer generation continuous flow devices particularly seem to support hemodynamic support well. While it is common practice to implant ICDs in patients with LVADs and a history of ventricular arrhythmias, the efficacy behind this practice at preventing sudden death in this population is unknown. In this review, we highlight what is already known about the complications, management and treatment of atrial and ventricular arrhythmias in patients with LVAD devices.     

左心辅助对右心功能影响的实验研究

目的　比较左心辅助对正常及急性缺血性功能不全右心室血流动力学的影响 ,初步探讨左心辅助后右心衰的发生原因。方法　以左心房 -主动脉旁路方式植入左心辅助装置于健康成年犬心脏 ,以 70 %辅助流率行左心辅助 ,在辅助前后记录中心静脉压 (CVP)、心输出量 (CO)、平均动脉压 (MAP)、肺动脉压 (PAP)、右心室最大收缩压(RVSPmax)、右心室最大收缩压一阶导数 (RVdp/dtmax)。停左心辅助并结扎右冠状动脉 ,5min后再行左心辅助 ,分别在辅助前后记录上述指标。结果　在右心功能正常时 ,左心辅助后肺动脉压下降 17% (P <0 0 1) ,其他血流动力学指标无明显变化 ;在右心功能不全时行左心辅助后 ,CVP上升 2 % (P>0 0 5 ) ,CO下降 4 % (P <0 0 5 ) ,MAP下降 7% (P <0 0 5 ) ,PAP下降 33% (P <0 0 1) ,RVSPmax及RVdp/dtmax分别下降18%和 14 % (P <0 0 1)。结论　在正常及急性缺血性功能不全右心室行左心辅助后血流动力学的不同变化趋势表明 ,原已存在功能损害的右心室能否承受LVAD应用后所产生的血流动力学的变化是左心辅助应用后发生右心衰的主要原因     

Prevalence, predictors, and mortality significance of the causative arrhythmia in patients with electrical storm

INTRODUCTION: Electrical storm (ES) is characterized by either refractory ventricular tachycardia (VT) or ventricular fibrillation (VF). However, little is known about the prevalence, predictors, and mortality implications of the causative arrhythmia in ES. We sought to assess the prevalence, predictors, and survival significance of VT and VF as the causative arrhythmia of ES in implantable cardioverter defibrillator (ICD) patients. METHODS AND RESULTS: Consecutive patients from January 2000 to December 2002 who presented to the ICD clinic with > or = 2 separate ventricular arrhythmic episodes requiring shock within 24 hours were included in the study. ICD interrogation confirmed the number of shocks and provided electrograms for interpretation of the causative arrhythmia. Patients were grouped as VF or VT according to the causative arrhythmia. Their prevalence, predictors, and mortality rates were compared. Of 2,028 patients assessed in the ICD clinic, 208 (10%) presented with ES. VF was the cause of ES in 99 of 208 patients, for an overall prevalence of 48%. Original ICD indication, coronary artery disease, and amiodarone therapy were predictive for the causative arrhythmia. There was no mortality difference between the VT and VF groups; however, both groups had significantly increased mortality compared to a control ICD population without ES. CONCLUSION: VF is the causative arrhythmia for a sizable proportion of patients with ES. The initial ICD indication, coronary artery disease, and amiodarone therapy are predictors of the causative arrhythmias in ES. There does not appear to be any mortality difference between ES patients with VT and VF, but mortality is increased in patients with ES versus control ICD patients without ES.     

Cardiac stereotactic radiation therapy for refractory ventricular arrhythmias in patients with left ventricular assist devices

Left ventricular assist device (LVAD) implantation is an established treatment for patients with advanced heart failure refractory to medical therapy. However, the incidence of ventricular arrhythmias (VAs) is high in this population, both in the acute and delayed phases after implantation. About one-third of patients implanted with an LVAD will experience sustained VAs, predisposing these patients to worse outcomes and complicating patient management. The combination of pre-existing myocardial substrate and complex electrical remodeling after LVAD implantation account for the high incidence of VAs observed in this population. LVAD patients presenting VAs refractory to antiarrhythmic therapy and catheter ablation procedures are not rare. In such patients, treatment options are extremely limited. Stereotactic body radiation therapy (SBRT) is a technique that delivers precise and high doses of radiation to highly defined targets, reducing exposure to adjacent normal tissue. Cardiac SBRT has recently emerged as a promising alternative with a growing number of case series reporting the effectiveness of the technique in reducing the VA burden in patients with arrhythmias refractory to conventional therapies. The safety profile of cardiac SBRT also appears favorable, even though the current clinical experience remains limited. The use of cardiac SBRT for the treatment of refractory VAs in patients implanted with an LVAD are even more scarce. This review summarizes the clinical experience of cardiac SBRT in LVAD patients and describes technical considerations related to the implementation of the SBRT procedure in the presence of an LVAD.     

Effects of left ventricular assist device on pulmonary functions and pulmonary hemodynamics: A meta-analysis

BACKGROUNDGiven current evidence, the effect of left ventricular assist device (LVAD) implantation on pulmonary function tests remains controversial.AIMTo better understand the factors contributing to the changes seen on pulmonary function testing and the correlation with pulmonary hemodynamics after LVAD implantation.METHODSElectronic databases were queried to identify relevant articles. The summary effect size was estimated as a difference of overall means and standard deviation on a random-effects model.RESULTSA total of four studies comprising 219 patients were included. The overall mean forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and diffusion lung capacity of carbon monoxide (DLCO) after LVAD implantation were significantly lower by 0.23 L (95%CI: 0.11-0.34, P = 00002), 0.18 L (95%CI: 0.03-0.34, P = 0.02), and 3.16 mmol/min (95%CI: 2.17-4.14, P < 0.00001), respectively. The net post-LVAD mean value of the cardiac index was significantly higher by 0.49 L/min/m² (95%CI: 0.31-0.66, P < 0.00001) compared to pre-LVAD value. The pulmonary capillary wedge pressure and pulmonary vascular resistance were significantly reduced after LVAD implantation by 8.56 mmHg (95%CI: 3.78-13.35, P = 0.0004), and 0.83 Woods U (95%CI: 0.11-1.55, P = 0.02), respectively. There was no significant difference observed in the right atrial pressure after LVAD implantation (0.61 mmHg, 95%CI: -2.00 to 3.32, P = 0.65). Overall findings appear to be driven by studies using HeartMateII devices.CONCLUSIONLVAD implantation might be associated with a significant reduction of the spirometric measures, including FEV1, FVC, and DLCO, and an overall improvement of pulmonary hemodynamics.     

Management of monomorphic ventricular tachycardia electrical storm in structural heart disease

Electrical storm (ES) is a life-threatening condition that is defined by three or more episodes of sustained ventricular tachycardia (VT), ventricular fibrillation (VF), or appropriate shocks from an implantable cardioverter defibrillator (ICD) within 24 hours. The most common form of ES is monomorphic VT. It carries poor outcome despite all available intervention therapies. The therapies include rapid recognition of the condition, treatment of the reversible causes, ICD-reprogramming, antiarrhythmic drugs, sedation, and catheter ablation (CA). The first line antiarrhythmic drugs are amiodarone and β-blockers with superiority of propranolol over the others. The long-term use of the antiarrhythmic drugs is limited due to their adverse effects and drug-related proarrhythmic effect. The basic mechanism of monomorphic VT is re-entry pathway which can be targeted by CA. CA should be considered in drug refractory ES and patients should be referred in early course of disease. There are reported studies which showed the superiority of CA over the medical treatment in reducing the arrythmia burden and ICD appropriate shock. The survival benefit has been reported after successful ablation of ES in case series but to date no randomized control trial shows mortality benefit.     

Short and long term outcomes of 200 patients supported by continuous-flow left ventricular assist devices

AIM: To study the institutional experience over 8 years with 200 continuous-flow (CF) - left ventricular assist devices (LVAD). METHODS: We evaluated our institution’s LVAD database and analyzed all patients who received a CF LVAD as a bridge to transplant (BTT) or destination therapy from March 2006 until June 2014. We identified 200 patients, of which 179 were implanted with a HeartMate II device (Thoratec Corp., Pleasanton, CA) and 21 received a Heartware HVAD (HeartWare Inc., Framingham, MA). RESULTS: The mean age of our LVAD recipients was 59.3 years (range 17-81), 76% (152/200) were males, and 49% were implanted for the indication of BTT. The survival rate for our LVAD patients at 30 d, 6 mo, 12 mo, 2 years, 3 years, and 4 years was 94%, 86%, 78%, 71%, 62% and 45% respectively. The mean duration of LVAD support was 581 d (range 2-2595 d). Gastrointestinal bleeding (was the most common adverse event (43/200, 21%), followed by right ventricular failure (38/200, 19%), stroke (31/200, 15%), re exploration for bleeding (31/200, 15%), ventilator dependent respiratory failure (19/200, 9%) and pneumonia (15/200, 7%). Our driveline infection rate was 7%. Pump thrombosis occurred in 6% of patients. Device exchanged was needed in 6% of patients. On multivariate analysis, preoperative liver dysfunction, ventilator dependent respiratory failure, tracheostomy and right ventricular failure requiring right ventricular assist device support were significant predictors of post LVAD survival. CONCLUSION: Short and long term survival for patients on LVAD support are excellent, although outcomes still remain inferior compared to heart transplantation. The incidence of driveline infections, pump thrombosis and pump exchange have declined significantly in recent years.     

Endocardial catheter ablation of ventricular tachycardia in patients with ventricular assist devices

BACKGROUND: The outcomes of patients with ventricular assist devices (VADs) who undergo catheter ablation for ventricular tachycardia (VT) have not been reported. OBJECTIVE: The purpose of this study was to assess the feasibility, safety, and efficacy of endocardial VT ablation in patients with VADs. METHODS: We retrospectively reviewed three cases at our institution where endocardial catheter ablation was performed in patients with VADs and incessant VT. RESULTS: Three patients with underlying cardiomyopathies and VADs underwent VT ablation for incessant VT refractory to multiple antiarrhythmic medications. In each case, VT was either eliminated or significantly ameliorated by catheter ablation. No procedure-related complications occurred. The hemodynamic stability afforded by the VAD played an important role in facilitating ablation in two of the cases. CONCLUSION: Catheter ablation for VT in VAD patients appears to be feasible, safe, and effective based on our initial experience. Several technical issues, such as decreases in ventricular volumes that can limit maneuverability of the ablation catheter and potential entrapment of the mapping catheter in the inflow cannula, need to be considered at the time of ablation.     

左心室辅助装置逆转心衰病理改变的分子机制研究进展

随着生活水平的提高和寿命的延长,心力衰竭在中国的发病率成逐年上升趋势。目前临床上心衰诊断一经确定,5年内的死亡率超过60％,终末期心衰患者预后更差,即使经过药物治疗,1年内的死亡率仍达75％。随着疾病进展,心脏对药物治疗的反应不断减弱,因此疾病后期,供临床医生选择的有效治疗手段十分有限,患者的生存率和生活质量受到很大影响。     

Prevalence and prognosis of ventricular tachycardia/ventricular fibrillation in patients with post-infarction left ventricular aneurysm: Analysis of 575 cases

Background

We investigated the prevalence of ventricular tachycardia/ventricular fibrillation (VT/VF) in Post-infarction left ventricular aneurysm (PI-LVA) patients and analyze clinical outcomes in patients presenting with VT/VF.