Risk factors predictive of right ventricular failure after left ventricular assist device implantation

Temporary percutaneous right ventricular support using a centrifugal pump in patients with postoperative acute refractory right ventricular failure after left ventricular assist device implantation

OBJECTIVE

Acute right ventricular (RV) failure is a life-threatening condition with a poor prognosis, and sometimes the use of mechanical circulatory support is inevitable. In this article, we describe our experience using a centrifugal pump as a temporary percutaneous right ventricular assist device (RVAD) in patients with postoperative acute refractory RV failure after left ventricular assist device (LVAD) implantation.

METHODS

We retrospectively reviewed eight consecutive patients with acute RV failure who underwent temporary percutaneous RVAD implantation using a centrifugal pump after LVAD implantation between April 2008 and February 2011. A Dacron graft was attached to the main pulmonary artery and passed through a subxiphoid exit, where the outflow cannula was inserted. The inflow cannula was percutaneously cannulated using Seldinger's technique in the femoral vein. The chest was definitely closed. The technique allowed bedside removal, avoiding chest re-opening.

RESULTS

The median patient age was 52 years (range: 41-58). The median duration of support was 14 days (range: 12-14). RV systolic function improved; central venous pressure and mean pulmonary artery pressure decreased significantly after RVAD support. In three patients, an oxygenator was integrated into the RVAD due to impaired pulmonary function. Six patients were successfully weaned. Five patients survived to hospital discharge. Technical problems or serious complications concerning decannulation were not observed.

CONCLUSION

This report suggests that implantation of temporary percutaneous RVAD using a centrifugal pump is a safe alternative in the treatment of postoperative acute refractory RV failure. Ease of device implantation, weaning, explantation, and limited number of complications justify a liberal use.

[Improvements in implantable mechanical circulatory support systems : literature overview and update]

In recent years, ventricular assist devices (VAD) supporting the left (LVAD), the right (RVAD) or both ventricles (BVAD) have rapidly emerged as the standard of care for advanced heart failure patients. Both the numbers and ages of patients in which they are used are rising worldwide, especially when used as a permanent support (bridge to destination, BTD). Due to the continuing lack of donor organs, these devices now represent a viable alternative to bridge patients to transplantation (BTT), with a 1-year survival rate of 86%. BTD, especially in long-term support, might be a valid, and the sole, option for those patients in whom heart transplantation is contraindicated. Patient selection, pre- and intra-operative preparation, as well as the timing of VAD implantation are important factors critical to successful circulatory support. While BTT remains the goal in the majority of patients, the number of permanent VADs (i. e. BTD) is rising significantly. Although explantation of a VAD system as a bridge to recovery (BTR) can be considered in only a small number of patients, it represents a very special part of this therapy modality.

Implantable continuous-flow right ventricular assist device: lessons learned in the development of a cleveland clinic device

Although the need for right ventricular assist device (RVAD) support for right ventricular failure after the implantation of a continuous-flow left ventricular assist device has decreased, right ventricular failure still occurs in as many as 44% of patients after continuous-flow left ventricular assist device insertion. Cleveland Clinic's DexAide continuous-flow RVAD was implanted in 34 calves during the course of its development. This review discusses lessons learned in the design and development of an implantable continuous-flow RVAD that are drawn from the results of these in vivo studies, our clinical experience with RVAD support, and a review of previously published reports on clinical RVAD use.

Left ventricle assist device: when and which patients should we refer?

Progress in the medical treatment of patients with heart failure with systolic dysfunction, cardiac resynchronization therapy, internal cardiac defibrillators and multidisciplinary management programmes has resulted in dramatic improvements in survival and quality of life; however, this progress has led to an increase in the prevalence of advanced heart failure. In the context of organ shortage for cardiac transplantation, the technological developments in left ventricular assist devices, shown in recent positive clinical studies, provide real hope for patients with advanced heart failure. This article summarizes the most recent clinical studies concerning left ventricular assist devices and discusses for whom and when a left ventricular assist device should be proposed.

Ventricular assist devices: pharmacological aspects of a mechanical therapy

Heart failure (HF) is a global epidemic that continues to cause significant morbidity and mortality despite advances in medical therapy. Ventricular assist device technology has emerged as a therapeutic option to bridge patients with end-stage HF to heart transplantation or as an alternative to transplantation in selected patients. In some patients, mechanical unloading induced by ventricular assist devices leads to improvement of myocardial function and a possibility of device removal. The implementation of this advanced technology requires multiple pharmacological interventions, both in the perioperative and long-term periods, in order to minimize potential complications and improve patient outcomes. We herein review the latest available evidence supporting the use of specific pharmacological interventions and current practices in the care of these patients: anticoagulation, bleeding management, pump thrombosis, infections, arrhythmias, right ventricular failure, hypertension, desensitization protocols, among others. Areas of uncertainty and ground for future research are also highlighted.

Long-term use of the CentriMag® Ventricular Assist System as a right ventricular assist device: a case report

Right ventricular failure (RVF) following implantation of a left ventricular assist system (LVAS) is associated with high morbidity and mortality. 1 - 4 Numerous centers have reported short-term use of the CentriMag® Ventricular Assist System (CVAS) (Levitronix LLC, Waltham, MA) for treatment of cardiogenic shock, decompensated heart failure and right ventricular failure (RVF) following LVAS implantation. 5 - 9 The present report reviews the clinical course of a patient requiring long-term right ventricular support utilizing the CVAS, following a HeartMate® II LVAS (Thoratec Corp. Pleasanton, CA) implantation. Elevated cytotoxic antibody levels complicated the patient’s treatment plan by precluding orthotropic heart transplantation. The CVAS operated for 304 days without mechanical difficulty until replaced with the HeartWare® Ventricular Assist System (HeartWare Inc. Miramar, FL).

Comparison of preload-sensitive pressure and flow controller strategies for a dual device biventricular support system

The use of rotary left ventricular assist devices (LVADs) has extended to destination and recovery therapy for end-stage heart failure. Incidence of right ventricular failure while on LVAD support requires a second device be implanted to support the failing right ventricle. Without a commercially available implantable rotary right ventricular assist device, rotary LVADs are cannulated into the right heart and operation modified to provide suitable support for the pulmonary system. While this approach can alleviate the demand for transplant through long-term biventricular support, it uncovers a new challenge with respect to controller strategies for these dual device support systems. This study compares the preload sensitivity of rotary, dual device biventricular assistance controllers in light of their ability to adjust the flow rate according to physiological demand. A Frank-Starling-like flow controller which requires both inlet pressure and flow sensors is compared to pressure controllers which maintain atrial or inlet cannula pressures through the use of a single pressure sensor. It was found that cannula selection and the location of a pressure controller's single pressure sensor can be tailored to adjust the preload sensitivity. When located within the atria, this sensitivity is effectively infinite. Moving the sensor to the base of a 450-mm cannula, however, decreased the sensitivity to 0.22 (L/min)/mm Hg. This indicates the potential for simple and reliable VAD controllers with increased preload sensitivity without the need for complex controllers requiring an array of hemodynamic sensors.

Destination therapy with left ventricular assist devices: patient selection and outcomes

PURPOSE OF REVIEW

Destination therapy with a left ventricular assist device (LVAD) has the potential to effectively treat a large number of patients with advanced heart failure who are not eligible for heart transplantation. With the advent of continuous-flow LVADs, safe and effective long-term circulatory support is available for properly identified candidates.

RECENT FINDINGS

The highest mortality following LVAD implant is observed in the sickest patients (INTERMACS profile 1); therefore, there is an increasing trend toward selecting patients with INTERMACS profiles 2-5. The less-ill patients will be studied in the planned REVIVE-IT trial. The Heart Failure Survival Score, Seattle Heart Failure Model, and Destination Therapy Risk Score may provide guidance for patient selection and preoperative optimization therapy, but these tools need to be updated for current LVAD technology. The current 1-year survival rate for patients supported for destination therapy with a continuous-flow LVAD is 74%, which represents an increase of 6% since the clinical trial was completed 2 years ago.

SUMMARY

Substantial progress has been made concerning survival and quality of life since destination therapy was first introduced 10 years ago. Advances in patient selection, improved LVAD technology, and optimized treatment strategies provide much optimism for the treatment of more heart failure patients in the future.

Multivariate risk scores and patient outcomes in advanced heart failure

Significant improvements in survival have occurred for patients with advanced heart failure, with an increasing array of therapeutic options sharing quite varied properties of cost, invasiveness, and impact on life expectancy. Risk models allow patients and providers to achieve a better understanding of prognosis than is possible through unstructured holistic assessment. This article reviews scoring systems for heart failure prognostication in the general sense and in the setting of providing answers to specific clinical queries. Topics addressed include outpatient survival, risk of inpatient and post-discharge mortality, potential changes to clinician decision-making through better understanding of prognosis, and mortality after having a left ventricular assist device placed or receiving an implantable cardiac-defibrillator.

Assessment of right pump outflow banding and speed changes on pulmonary hemodynamics during biventricular support with two rotary left ventricular assist devices

The absence of an effective, easily implantable right ventricular assist device (RVAD) significantly diminishes long-term treatment options for patients with biventricular heart failure. The implantation of a second rotary left ventricular assist device (LVAD) for right heart support is therefore being considered; however, this approach exhibits technical challenges when adapting current devices to produce the lower pressures required of the pulmonary circulation. Hemodynamic adaptation may be achieved by either reducing the rotational speed of the right pump impeller or reducing the diameter of the right outflow cannula by the placement of a restricting band; however, the optimal value and influence of changes to each parameter are not well understood. Hemodynamics were therefore investigated using different banding diameters of the right outflow cannula (3-6.5 mm) and pump speeds (500-4500 rpm), using two identical rotary blood pumps coupled to a pulsatile mock circulation loop. Reducing the speed of the right pump from 4900 rpm (for left ventricle support) to 3500 rpm, or banding the Ø10 mm (area 78.5 mm²) right outflow graft to Ø5.4 mm (22.9 mm²) produced suitable hemodynamics. Pulmonary pressures were most sensitive to banding diameters, especially when RVAD flow exceeded LVAD flow. This occurred between Ø5.3 and Ø6.5 mm (22.05-38.5 mm²) and speeds between 3200 and 4400 rpm, with the flow imbalance potentially leading to pulmonary congestion. Total flow was not affected by banding diameters and speeds below this range, and only increased slightly at higher values. Both right outflow banding or right pump speed reduction were found to be effective techniques to allow a rotary LVAD to be used directly for right heart support. However, the observed sensitivity to diameter and speed indicate that challenges may be presented when setting appropriate values for each patient, and control over these parameters is desirable.

Management of right ventricular failure in the era of ventricular assist device therapy

The increasing incidence of patients with advanced heart failure, limited donor availability, and continued advancements in the field of mechanical circulatory support have made implantation of left ventricular assist device therapy (LVAD) an attractive option for patients with end-stage heart failure. Perioperative right ventricular failure (RVF) occurs frequently in patients undergoing LVAD implantation and is associated with significant morbidity and mortality. This review will discuss the pathophysiology of RVF, recent efforts to risk-stratify patients preoperatively, and current preoperative, perioperative, and postoperative management strategies.

Tricuspid valve repair with left ventricular assist device implantation: is it warranted?

BACKGROUND

Tricuspid regurgitation is common in patients with advanced heart failure. The ideal operative strategy for managing tricuspid valve regurgitation (TR) in patients undergoing left ventricular assist device (LVAD) implantation is unclear. This study was designed to evaluate the effect on outcomes of concomitant tricuspid valve repair (TVR) for moderate to severe (3(+)/4(+)) TR at the time of LVAD implantation.

METHODS

Patients with >3(+) TR who underwent LVAD implantation from 2005 to 2009 were retrospectively evaluated. Pre-, intra- and post-operative data, including hemodynamics, inotrope requirements and end-organ function parameters, were considered. Outcomes of patients receiving TVR were compared with those who did not receive TVR (NTVR).

RESULTS

Seventy-two LVADs were implanted during the study period. Forty-two (58%) patients had ≥ 3(+) TR prior to LVAD implantation. Eight patients underwent TVR and 34 patients did not undergo TVR (NTVR). There were no significant differences in baseline characteristics or severity of TR between the two groups. The TVR group had a longer cardiopulmonary bypass time (p < 0.01) and required more blood products (p < 0.05). Higher post-operative creatinine and blood urea nitrogen (BUN) values were noted in the TVR group. One patient in the TVR group and 3 patients in the NTVR group required right-sided mechanical assistance (p = 0.6). There was no significant difference in short- or long-term mortality between the two groups.

CONCLUSIONS

TVR for ≥ 3(+) TR prolonged operative time and showed similar outcomes compared with LVAD implantation alone. A benefit of performing TVR was not demonstrated. As such, TVR may not be necessary at the time of LVAD implantation.

The Pharmacotherapy of the HeartMate II, a Continuous Flow Left Ventricular Assist Device, in Patients with Advanced Heart Failure: Integration of Disease, Device, and Drug

Advanced heart failure continues to be a significant cause of morbidity and mortality in the US. Patients with advanced heart failure have a poor prognosis without cardiac transplantation. The use of left ventricular assist devices (LVADs) as destination therapy for these patients is therefore expected to increase in the coming years as technology advances. The HeartMate II, a continuous flow implantable device, is currently the only LVAD that has been approved by the Food and Drug Administration for destination therapy in patients with advanced heart failure. The pharmacotherapy associated with this device is very complex and, therefore, the need for expertly trained clinical pharmacists to care for this expanding patient population wilt also likely increase. Unfortunately, most pharmacists are unfamiliar with the effect of LVADs on the physiology and pharmacotherapy of a patient's heart failure. The purpose of this article is to give clinical pharmacists an introduction to the most common pharmacotherapeutic issues for patients with LVADs and present practical solutions for managing common drug therapy problems.