Aortic Regurgitation in Patients with Left Ventricular Assist Devices

Aortic insufficiency (AI) occurs as a complication in 25% to 37% of cases that receive left ventricular assist devices (LVAD). The incidence increases after implant by 1% to 6% per month of continued support. Uncertainty remains over the appropriate management of pump speeds to help delay this deterioration (complete emptying versus allowing native ventricular function open the aortic on a regular basis). Significant AI can lead to hemodynamic impairment with adverse outcomes over time. Due to the recirculation of blood, the calculated cardiac output of the LVAD may be markedly skewed. A number of surgical techniques have been proposed for the prevention and management of AI in the setting of LVAD therapy. This chapter details the causes, treatment strategies, and outcomes associated with this complication.

Postoperative Management after Assist Device Implantation

Post-operative ICU management of the MCS patient represents one of the most complex challenges in the current health care environment. With increasing experience, improvements in this arena have led to dramatic improvements in the outcomes of these patients. In this chapter, we detail several of the post-operative challenges in the ICU including ventilator management, bleeding complications, hemodynamic optimization, arrhythmias, and CPR.

Providing Mechanical Support to Children Size and Anatomical Considerations

Mechanical circulatory support (MCS) in children has changed greatly during the past two decades. Historically, extracorporeal membranous oxygenation was the only mechanical support option for children. The introduction and widespread use of the Berlin Heart EXCOR pump—a pulsatile, pneumatic compression device still commonly used in small children—allowed the use of ventricular assist devices (VAD). This chapter describes the leading MCS options in small children with complex pathology and reviews the evolution of cannulation strategies for long-term support. It describes an advanced imaging technique that allows devices to be “virtually fit” to patients before implantation, a technology that may increase the number of eligible patients receiving devices thought to be too large by body surface area alone. Although body imaging is required, virtual fit will supplant the antiquated use of weight and body surface area in planning complicated implantations. Finally, the chapter presents MCS management strategies for different congenital anomalies, such as single-ventricle pathology and arterial transpositions.

Implantation of Continuous-Flow Left Ventricular Assist Devices via Sternotomy Technical Considerations

Meticulous attention to detail at the time of surgical implantation can have a significant impact on postoperative outcomes. This chapter describes the authors’ technique for optimal LVAD insertion, along with a brief discussion on some of the concomitant procedures that are frequently required.

Anesthesia

The anesthetic care of the left ventricular assist device (LVAD) recipient presents to the anesthesiologist a unique set of challenges which must be skillfully managed for the successful completion of this complex surgical procedure. The anesthesiologist must perform a thorough preoperative evaluation and carefully assess the patient’s cardiovascular, pulmonary, renal, and hepatic systems. Special consideration to the risk of post-implantation right ventricular (RV) dysfunction is critical. In patients with advanced heart failure, a well-formulated anesthetic management plan must be developed to provide adequate anesthesia while at the same time preventing hemodynamic deterioration. The performance of a comprehensive transesophageal echocardiogram study is essential for identifying potential issues that may need to be addressed during the surgery. The post-cardiopulmonary bypass period is fraught with several challenges which the anesthesiologist must address, such as RV dysfunction or failure, vasoplegia, and coagulopathy. The transition of care to the ICU is facilitated by the application of a standardized checklist to ensure that all critical information is conveyed to the critical care providers. The anesthesiologist also frequently provides care for the LVAD patient undergoing a non-cardiac surgery or procedure. A careful preoperative evaluation and a thorough understanding of the technology and physiology of the LVAD patient is essential to the development of a safe and sensible anesthetic management plan.

Extracorporeal Membrane Oxygenation

This chapter examines the indications, applications, and complications of modern extracorporeal membrane oxygenation (ECMO). The safety profile of ECMO has improved through advancements in devices, components, and routine management, resulting in improved outcomes and an expanded range of applications. Currently, ECMO can provide cardiopulmonary support in reversible conditions, such as post-cardiotomy shock, acute respiratory failure, extracorporeal cardiopulmonary resuscitation, bridge to transplant, complex airway repairs, and massive pulmonary embolism, among others. The chapter focuses on the primary factors involved in using ECMO successfully: appropriate patient selection, optimal cannulation strategy, and availability of comprehensive medical resources (or a referral agreement with a comprehensive ECMO center) to handle emergent ECMO complications and to absorb the substantial resource requirements of treating patients with ECMO.

Preoperative Strategies for Optimizing Mechanical Circulatory Support

Several validated risk models can help determine whether patients with advanced heart failure should be considered for mechanical circulatory support based on its potential survival advantage. Once a patient is a candidate for device therapy, an understanding of these risk models can help inform decisions about modifying risk factors to provide the best postsurgical outcomes. Specific preoperative factors that can be addressed include the adequacy of perfusion, volume status, and the status of non-cardiac organ systems (e.g., the pulmonary, infectious, hematologic, renal systems). Additionally, an understanding of preoperative right ventricular hemodynamics and function can help alert providers to patients with an increased need for postoperative right-ventricular support. The chapter reviews several risk-stratification models, as well as the approach used by the authors’ institution to optimize the preoperative treatment of patients before implementing mechanical circulatory support.

Cardiac and Physical Rehabilitation

Cardiac and physical rehabilitation featuring exercise training (ET) is an important component of secondary prevention. Patients with advanced heart failure (HF) and dependent on mechanical circulatory support (MCS) who participate in cardiac and physical rehabilitation demonstrate physiological adaptations and improvements in exercise capacity and prognosis. Immediate post-implant and long-term engagement in ET works to strengthen central and peripheral oxygen-dependent metabolic pathways as a primary means for which clinical and real-world benefits are gained. Accordingly, this chapter presents (1) a contemporary review of the role that cardiac and physical rehabilitation plays in HF and MCS; (2) discussion focused on the importance of understanding exercise physiology as the basis for ET; (3) evidence-based recommendations for deploying safe and individualized ET in the immediate- to long-term postoperative window; and (4) identification of key research areas focused on MCS and secondary prevention needed to advance the mechanistic understanding of the benefit linked to ET, to gain universal support for cardiac and physical rehabilitation, and to improve patient utilization of cardiac and physical rehabilitation.

Modalities of Left Ventricular Assist Device Optimization

Continuous flow left ventricular assist devices (LVADs) are a viable long-term option to the end-stage heart failure patient, with improvements in hemocompatibility seen with newer generation devices. The complex interplay of native myocardial contractility, state of the right ventricle, and presence of aortic insufficiency, among other factors, governs cardiac performance in addition to that from the pump. Deliberate speed adjustments by non-invasive and invasive methods can improve the LVAD hemodynamic profile in a manner tailored to the individual patient. Individualized adjustments in pump parameters by these methods may reduce the longitudinal burden of LVAD-related adverse events.

Counterpulsation Circulatory Assist Devices

An increasing number of patients with heart failure need advanced therapy. Heart transplantation remains the definitive long-term treatment, but its use is limited by the low number of donor hearts. This limitation has led to the development of mechanical circulatory support devices that assist cardiac function by direct blood pumping (e.g. ventricular assist devices) and counterpulsation (e.g. the intra-aortic balloon pump). Ventricular assist devices provide long-term treatment for heart failure but are associated with potentially severe complications, such as driveline infection, stroke, and gastrointestinal bleeding. Counterpulsation improves cardiac function by augmenting diastole and reducing afterload, which increases coronary perfusion and decreases cardiac workload. Since the concept was introduced in 1960s, several devices have been used in humans. The intra-aortic balloon pump, a counterpulsation device, is the most commonly used device for short-term support as a bridge to transplant or recovery. A minimally invasive counterpulsation device, such as an intravascular ventricular assist system that allows ambulation, could potentially offer versatile solutions for long-term heart failure therapy or as a bridge to transplant or to recovery. The intravascular ventricular assist system has fewer complications and avoids the need for sternotomy or thoracotomy.