Mechanical Circulatory Support in the New Era: An Overview

Kiran Shekar; Shaun D. Gregory; John F. Fraser

Disclosures

Crit Care. 2016;20(66) 

In This Article

Case Vignette

A 28-year old, previously fit male was admitted to a peripheral intensive care unit (ICU) with cardiogenic shock of uncertain origin. Electrocardiogram (EKG) demonstrated no acute ischemic changes, but there was an increase in plasma cardiac troponin I concentration (2/l ng/ml). He deteriorated rapidly following a run of ventricular arrhythmias that required brief CPR and electric cardioversion. He was subsequently commenced on inotropes and pressors and was intubated and mechanically ventilated. A transthoracic echo demonstrated an akinetic thick ventricular wall, globally diminished cardiac function with a left ventricular ejection fraction (LVEF) of 5 % with no significant valvular abnormalities. An intra-aortic balloon pump (IABP) was inserted. Over the next 6/h he developed more sustained runs of ventricular arrhythmias with escalating inotrope requirement and early evidence of hepatic and renal dysfunction. The local ECMO center retrieved the patient safely, after establishing peripheral VA-ECMO support, leaving the IABP in situ. Upon arrival at the ECMO center, loss of pulsatility on arterial waveform suggested loss of aortic valve opening, which was confirmed by echocardiography. High intensity anticoagulation, increased inotropes, afterload reduction with nitrates and higher positive end-expiratory pressure (PEEP) were augmented with amiodarone infusion. A follow-up echocardiography hours later demonstrated a distended left ventricle with evidence of some early thrombus in the ventricle and possibly the aortic root. It was predicted that peripheral VA-ECMO was likely to fail and could lead to central thromboembolic and pulmonary complications. Less invasive options for decompression of the left ventricle, such as an atrial septostomy, were considered but excluded. Other venting options included percutaneous VADs, such as Impella (Abiomed, Aachen, Germany) or TandemHeart (CardiacAssist, Inc., Pittsburgh, PA, USA), but these were not available.

Based on a presumptive diagnosis of acute myocarditis and potential for recovery, his MCS configuration was changed to a temporary biventricular assist device (BiVAD) configuration using two ECMO circuits and centrifugal pumps (CentriMag, Levitronix LLC, Waltham, MA). A Quadrox D Oxygenator (Maquet, Rastatt, Germany) was included in the right ventricular assist device (RVAD) circuit to facilitate gas exchange and temperature control in the early postoperative period. The surgical cannulation strategy employed (transfemoral right atrial [RA] drainage → allograft to pulmonary artery [PA] return; and left ventricular [LV] apex drainage to aorta return) allowed for awakening, mobilization and exercise in bed on BiVAD support. This was necessary to allow physical conditioning and urgent listing for a heart transplant if cardiac recovery failed to occur. Cardiac tissue at the time of LV apical cannulation demonstrated fulminant giant cell myocarditis raising concerns about cardiac recovery.

After hemostasis had been achieved, the oxygenator was removed from the circuit on postoperative day 2 and a tracheostomy was performed to allow weaning from sedation and ventilation. Over the next 2 weeks, the patient was liberated from mechanical ventilation and the tracheostomy removed, with the patient remaining stable on the BiVAD, with some physical recovery, but no cardiac recovery. He was urgently listed for a heart transplant after confirming eligibility. No organ became available for transplant in the following two weeks whilst on temporary BiVAD. Given the patient had a less favorable blood group and a more ambulatory support strategy was needed to move forward, the temporary LVAD was converted to a left side long-term implantable rotary VAD (HVAD, HeartWare, Framingham, MA). Support from the temporary RVAD was continued due to concerns of RV failure post-LVAD implantation.

The early post-VAD insertion was complicated by bleeding requiring reopening but over the next few days a tracheotomy was again performed and rehabilitation was recommenced. Over the next 10 days, the RVAD was removed and the patient was weaned off ventilation and was eventually discharged from the ICU on LVAD support. He received inotropes for RV support in the ward for another 2 weeks. He was relisted for heart transplant a few weeks later. Three months later he received a heart transplant and was discharged to the ward after 1 week in the ICU and subsequently discharged home after a prolonged rehabilitation.

This case illustrates how a spectrum of MCS strategies was used to successfully bridge a young patient with acute heart failure to heart transplantation. Equally this case demonstrates the resources, forward-planning and multidisciplinary inputs that are required to provide such a level of care. Although there are understandable concerns regarding the costs associated with these therapies, they are likely to become more widely used, and with appropriate usage, their costs will drop, as with all new technology.

This article will discuss the bridging options in more detail in the sections below to reflect the advancements in MCS and to reinforce the importance of choosing the 'right perfusion strategy for the right patient at the right time'. The intensivist will be a key contributor to MCS – both in terms of patient selection, and in determining and enacting at least the initial percutaneous strategies – either pre- or post-retrieval from peripheral centers to an advanced MCS center. This article will focus mainly on principles of various MCS strategies and will refer the readers elsewhere for more information on the technicalities of the devices used. Equally, this article discusses more commonly used devices only and is by no means a comprehensive review of all MCS devices in clinical use or development.

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