Ventricular assist device therapy

Left Ventricular Assist Devices: A Primer for the Non-Mechanical Circulatory Support Provider

Survival after implant of a left ventricular assist device (LVAD) continues to improve for patients with end-stage heart failure. Meanwhile, more patients are implanted with a destination therapy, rather than bridge-to-transplant, indication, meaning the population of patients living long-term on LVADs will continue to grow. Non-LVAD healthcare providers will encounter such patients in their scope of practice, and familiarity and comfort with the physiology and operation of these devices and common problems is essential. This review article describes the history, development, and operation of the modern LVAD. Common LVAD-related complications such as bleeding, infection, stroke, and right heart failure are reviewed and an approach to the patient with an LVAD is suggested. Nominal operating parameters and device response to various physiologic conditions, including hypo- and hypervolemia, hypertension, and device failure, are reviewed.

Ablation therapy for ventricular arrhythmias in patients with LVAD: Multiple faces of an electrophysiological challenge

Left ventricular assist device implantation is a recognized treatment option for patients with advanced heart failure refractory to medical therapy and can be used both as bridge to transplantation and as destination therapy. The risk of ventricular arrhythmias is common after left ventricular assist device implantation and is influenced by pre-, peri and post-operative determinants. The management of ventricular arrhythmias can be a challenge when they become refractory to medication or to device therapy and their impact on prognosis can be detrimental despite the mechanical support. In this setting, catheter ablation is being increasingly recognized as a feasible option for patients in which standard therapeutic strategies fail, but also with preventive purpose. Catheter ablation is being increasingly considered for the management of ventricular arrhythmias in patients with left ventricular assist device despite complex clinical and technical peculiarities due to the characteristics of the mechanical support. Much conflicting data exist regarding the predictors of success of the procedure and the rate of recurrence. In this review we discuss the latest evidences regarding catheter ablation of ventricular arrhythmias in this subset of patients, focusing on clinical characteristics, arrhythmia etiology, technical aspects and postprocedural features which must be considered by the electrophysiologist.

Perioperative management of patients with left ventricular assist devices undergoing noncardiac surgery

Aim:

The aim of this study was to describe our institutional experience, primarily with general anesthesiologists consulting with cardiac anesthesiologists, caring for left ventricular assist device (LVAD) patients undergoing noncardiac surgery.

Materials and Methods:

This is a retrospective review of the population of patients with LVADs at a single institution undergoing noncardiac procedures between 2009 and 2014. Demographic, perioperative, and procedural data collected included the type of procedure performed, anesthetic technique, vasopressor requirements, invasive monitors used, anesthesia provider type, blood product management, need for postoperative intubation, postoperative disposition and length of stay, and perioperative complications including mortality.

Statistical Analysis:

Descriptive statistics for categorical variables are presented as frequency distributions and percentages. Continuous variables are expressed as mean ± standard deviation and range when applicable.

Results:

During the study, 31 patients with LVADs underwent a total of 74 procedures. Each patient underwent an average of 2.4 procedures. Of the total number of procedures, 48 (65%) were upper or lower endoscopies. Considering all procedures, 81% were performed under monitored anesthesia care (MAC). Perioperative care was provided by faculty outside of the division of cardiac anesthesia in 62% of procedures. Invasive blood pressure monitoring was used in 27 (36%) procedures, and a central line, peripherally inserted central catheter or midline was in place preoperatively and used intraoperatively for 38 (51%) procedures. Vasopressors were not required in the majority (65; 88%) of procedures. There was one inhospital mortality secondary to multiorgan failure; 97% of patients survived to discharge after their procedure.

Conclusion:

At our institution, LVAD patients undergoing noncardiac procedures most frequently require endoscopy. These procedures can frequently be done safely under MAC, with or without consultation by a cardiac anesthesiologist.

Simulation of motor current waveforms in monitoring aortic valve state during ventricular assist device support

Monitoring of aortic valve (AV) opening and closure during left ventricular assist device (LVAD) heart pump support is crucial in preventing AV abnormalities and remodeling caused by anomalous resirculation. In this study, simulations of LVAD motor current waveforms were undertaken to investigate AV response to rotary blood pump assistance, as well as to detect AV open and close status under heart failure conditions. A two-dimensional fluid-structure interaction finite-element model is presented to predict AV state during LVAD outflow. The data will be useful in the development of a pump speed controller for optimal management of pump outflow.

Simulation of aortic valve dynamics during ventricular support

Existing commercially-used left ventricular assist devices (LVADs) make no attempt to automatically detect the aortic valve condition in their control methods to optimize ventricular assistance. An important design goal for LVADs is the ability to reliably and accurately detect aortic valve (AV) states during heart pump support that can cause harmful effects on AV structure and function. In this paper, we have investigated the correlation between AV performance and LVAD motor current as well as speed set points, simulating aortic valve blood flow, pressure, pump flow and LV mechanics using a simplified two-dimensional fluid-structure interaction finite-element model of AV dynamics.

Left ventricular assist device management and complications

Patients on long-term left ventricular assist device (LVAD) support present unique challenges in the intensive care unit. It is crucial to know the status of end-organ perfusion, which may require invasive hemodynamic monitoring with a systemic arterial and pulmonary artery catheter. Depending on the indication for LVAD support (bridge to decision or cardiac transplantation vs destination therapy), it is important to readdress goals of care with the patient (if possible) and their family after major events have occurred that challenge the survival of the patient.

Left Ventricular Assist Devices in the Management of Heart Failure

Mechanical circulatory support has emerged as an important therapy for advanced heart failure, with more than 18,000 continuous flow devices implanted worldwide to date. These devices significantly improve survival and quality of life and should be considered in every patient with end-stage heart failure with reduced ejection fraction who has no other life-limiting diseases. All candidates for device implantation should undergo a thorough evaluation in order to identify those who could benefit from device implantation. Long-term management of ventricular assist device patients is challenging and requires knowledge of the characteristic complications with their unique clinical presentations.

Simulation of motor current waveform as an index for aortic valve open-close condition during ventricular support

Monitoring of aortic valve (AV) opening and closure during heart pump support by a left ventricular assist device (LVAD) is crucial in preventing adverse events such as thrombus formation near the AV. In preventing adverse events such as thrombus formation near the AV. In this paper, simulations of LVAD motor current waveform were undertaken to evaluate its suitability for ascertaining aortic valve status. A two-dimensional fluid-structure interaction finite-element model is presented to predict AV closure during LVAD outflow, useful in the development of a pump speed controller.

Modeling aortic valve closure under the action of a ventricular assist device

The support of a failing heart with pump devices has been an essential element in cardiac health care for several decades. It is therefore important to understand the left ventricular response to the pumping action of these devices when connected to the native heart. Furthermore, monitoring of aortic valve opening and closure is important in avoiding valve stenosis and thrombogenesis during pump support. This paper reports the first steps in simulating the effects of outlet pump pressure on aortic valve closure of the heart assisted by an implantable blood pump. A two-dimensional fluid structure interaction aortic valve model is presented with blood flow in left ventricular chamber using the Arbitrary Lagrangian-Eulerian Finite Element Method formulation to predict the AV closure during outflow of blood from the left ventricle into the left ventricular assist device (LVAD).

The pharmacotherapy implications of ventricular assist device in the patient with end-stage heart failure

Advances in mechanical circulatory support, such as the use of ventricular assist devices (VADs), have become a means for prolonging survival in end-stage heart failure (HF). VADs decrease the symptoms of HF and improve quality of life by replacing some of the work of a failing heart. They unload the ventricle to provide improved cardiac output and end-organ perfusion, resulting in improvement in cardiorenal syndromes and New York Heart Association functional class rating. VADs are currently used asa bridge to heart transplantation, a bridge to recovery of cardiac function, or as destination therapy. Complications of VAD include bleeding, infections, arrhythmias, multiple organ failure, right ventricular failure, and neurological dysfunction. Patients with VAD have unique pharmacotherapeutic requirements in terms of anticoagulation, appropriate antibiotic selection, and continuation of HF medications. Pharmacists in acute care and community settings are well prepared to care for the patient with VAD. These patients require thorough counseling and follow-up with regard to prevention and treatment of infections, appropriate levels of anticoagulation, and maintenance of fluid balance. A basic understanding of this unique therapy can assist pharmacists in attending to the needs of patients with VAD.

On the Representation of Turbulent Stresses for Computing Blood Damage

Computational prediction of blood damage has become a crucial tool for evaluating blood-wetted medical devices and pathological hemodynamics. A difficulty arises in predicting blood damage under turbulent flow conditions because the total stress is indeterminate. Common practice uses the Reynolds stress as an estimation of the total stress causing damage to the blood cells. This study investigates the error introduced by making this substitution, and further shows that energy dissipation is a more appropriate metric of blood trauma.

Cardiac cell therapies: the next generation

Although significant advances have been made in terms of pharmacological, catheter-based, and surgical palliation, heart failure remains a fatal disease. As a curative concept, regenerative medicine aims at the restoration of the physiologic cellular composition of diseased organs. So far, clinical cardiac regeneration attempts have only been moderately successful, but a better understanding of myocardial cell homeostasis and somatic as well as embryonic stem cell biology has opened the door for the development of more potent therapeutic cardiac regeneration strategies. Accumulating evidence indicates that the postnatal mammalian heart retains a pool of tissue-specific progenitor cells and is also repopulated by cells from extracardiac sources. However, this intrinsic myocardial regeneration potential clearly needs to be augmented by either manipulation of the cell cycle of differentiated cells, activation of resident cardiac progenitor cells, and/or the transplantation of exogenous cells. This review summarizes the recent developments in cardiac regenerative medicine, many of which may find their way into the clinical setting in the foreseeable future.

Interventions for treating peripartum cardiomyopathy to improve outcomes for women and babies

BACKGROUND

Peripartum cardiomyopathy (PPCM or PCMO) is a rare disease of unknown etiology, characterised by an acute onset of heart failure in women in the late stage of pregnancy or in the early months postpartum.

OBJECTIVES

To assess the effectiveness and safety of any intervention for the care of women and/or their babies with a diagnosis of peripartum cardiomyopathy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 July 2010) and the reference lists of identified studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of any intervention for treating peripartum cardiomyopathy. Such interventions include: drugs; cardiac monitoring and treatment; haemodynamic monitoring and treatments; supportive therapies and heart transplant.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.

MAIN RESULTS

We identified and included one pilot study, involving 20 women, undertaken in South Africa. Women were diagnosed postnatally and included in the study within 24 hours of diagnosis.

AUTHORS' CONCLUSIONS

There are insufficient data to draw any firm conclusions. Treatment with bromocriptine appears promising, although women would be unable to breastfeed due to suppression of lactation.

Update on ventricular assist devices

PURPOSE OF REVIEW

Over the past two decades, medicine has seen a robust increase in the use of ventricular assist devices. The purpose of this review is to update the information concerning these devices, their advantages and disadvantages as well as their complications. This is essential, as the demand for these devices is increasing due to the increasing number of patients with end-stage heart failure and limited number of donor hearts available for transplantation.

RECENT FINDINGS

First-generation devices consisted of large, cumbersome consoles requiring patient immobilization and often times hospitalization in an ICU setting. Second-generation models focused on patient mobility and discharge from hospital with an improvement in infection rates as well as 1 and 2-year survival rates. Designs for newer devices are focusing on full implantation without percutaneous lines, axial flow mechanisms and patient comfort. Additionally, total artificial hearts are being designed for the treatment of biventricular failure. The indications for ventricular assist devices are also being expanded to include destination therapy and alternatives to cardiac transplantation, as the supply of organs continues to be limiting.

SUMMARY

This paper reviews the characteristics, outcomes and design of ventricular assist devices.