Mechanical circulatory assist devices: a primer for critical care and emergency physicians

Abstract

Mechanical circulatory assist devices are now commonly used in the treatment of severe heart failure as bridges to cardiac transplant, as destination therapy for patients who are not transplant candidates, and as bridges to recovery and "decision-making". These devices, which can be used to support the left or right ventricles or both, restore circulation to the tissues, thereby improving organ function. Left ventricular assist devices (LVADs) are the most common support devices. To care for patients with these devices, health care providers in emergency departments (EDs) and intensive care units (ICUs) need to understand the physiology of the devices, the vocabulary of mechanical support, the types of complications patients may have, diagnostic techniques, and decision-making regarding treatment. Patients with LVADs who come to the ED or are admitted to the ICU usually have nonspecific clinical symptoms, most commonly shortness of breath, hypotension, anemia, chest pain, syncope, hemoptysis, gastrointestinal bleeding, jaundice, fever, oliguria and hematuria, altered mental status, headache, seizure, and back pain. Other patients are seen for cardiac arrest, psychiatric issues, sequelae of noncardiac surgery, and trauma. Although most patients have LVADs, some may have biventricular support devices or total artificial hearts. Involving a team of cardiac surgeons, perfusion experts, and heart-failure physicians, as well as ED and ICU physicians and nurses, is critical for managing treatment for these patients and for successful outcomes. This review is designed for critical care providers who may be the first to see these patients in the ED or ICU.

Understanding Left Ventricular Assist Devices

“…These pumps differ in technical design, but all are continuous-flow pumps and have the following analogous components [3][4][5]10]: (1) an inflow cannula surgically implanted into the LV apex, conducting blood from the LV to the pump; (2) a pump enclosure that houses an impeller that circulates blood; (3) an outflow graft carrying blood from the pump to the aorta and systemic circulation; and (4) a surgically tunnelled driveline that connects the pump to an external controller that operates and monitors the pump function [2].…”

“…The most frequent complications occurring in the MCS patients are bleeding, driveline infections, thrombosis, device malfunction, right ventricular failure and arrhythmias [3][4][5]. Patients with MCS can also be admitted in ICU for non-specific aetiologies [3][4][5].…”

“…Encountered bleeding events (beyond 1 month after VAD implantation) are epistaxis, gastro-intestinal bleeding, intracranial haemorrhage and mediastinal and thoracic bleeding. Their management includes antiplatelet therapy arrest, reduction of the anticoagulation regimen and specific therapy if feasible (Gastroscopy, electrocoagulation in case of epistaxis even embolization) [3][4][5].…”

“…As a result, intensivists who might not have been trained in managing advanced heart failure patients, are increasingly likely to encounter patients requiring MCS at various points in their disease trajectory, especially during subsequent admissions for complications [3][4][5].…”

Invasive Treatment in Advanced (Stage-D) Heart Failure

“…, pump mechanism (volume displacement, axial, centrifugal), and the ventricle(s) supported (left, right, biventricular) [72].…”