Short-Term Ventricular Assist Devices as a Bridge to Decision/ Recovery

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1 Chapter 67 Short-Term Ventricular Assist Devices as a Bridge to Decision/ Recovery ALLA GOPALA KRISHNA GOKHALE CH. RAVIRAJU V.V.K. BHARADWAJA KODURU VENKATA RAMANA INTRODUCTION Heart diseases and heart failure have reached epidemic proportions in India with a majority of patients dying despite maximum medical therapy. Short-term ventricular assist devices (VADs) are man-made devices that provide temporary forward flow of blood in the body, assuming that ventricular function would recover early or a decision can be made about more durable devices or about heart transplantation, when it can be offered to the patient. Michael DeBakey, in 1963, implanted the first mechanical assist device for a patient with postcardiogenic shock after an aortic valve replacement. In 1966, DeBakey used a pneumatically driven diaphragm pump. In 1970s, successful heart transplantation programmes provided stimulation for the development of various VADs as a bridging therapy to heart transplantation, since several patients were dying due to advanced heart failure while waiting for heart transplantation. In 1978, Cooley used a pneumatically driven artificial LIOTTA heart for 3 days prior to heart transplantation. The Randomized Evaluation of Mechanical Assistance for Treatment of Congestive Heart Failure (REMATCH) trial 1, published in 2001, was the first prospective, randomized trial of patients with endstage heart failure in whom mechanical circulatory support with VADs demonstrated a significant survival advantage over patients receiving optimal medical therapy. The current VADs can be divided into subcategories like short-term versus long-term devices; paracorporeal (outside the human body) versus intracorporeal devices (implanted inside the body); pulsatile versus continuous flow devices; left-sided (LVAD) or right-sided (RVAD) or biventricular devices; full- versus partial-support devices; assist devices versus complete heart replacement (total artificial heart [TAH]); pneumatic or electrical devices and those which can be implanted percutaneously versus those needing surgery for implantation. IMPLANT STRATEGIES FOR USING SHORT-TERM VENTRICULAR ASSIST DEVICES 2 Bridge to decision (BTD): A short-term VAD may be used when a patient is in acute cardiogenic shock to stabilize the patient and to assess the neurological status and presence or absence of multi-organ failure and its reversibility. Later a decision about the next level of treatment like candidacy for heart transplantation or long-term VADs can be planned while the patient is still on short-term VAD. Bridge to recovery: Short-term VADs are helpful as a temporary circulatory support to unload the ventricle, while the myocardium can recover from an acute injury without any further need of transplant or a permanent LVAD. Bridge to candidacy (BTC): Some patients with reversible end-organ dysfunction, malnutrition, high pulmonary vascular resistance, reversible comorbidities like weight loss and smoking cessation benefit from short-term VADs. Bridge to transplant (BTT): Usually long-term VADs are preferred option. Sometime short-term VADs may be used for patients suitable for transplantation but suffering from low cardiac output, in order to prevent end-organ dysfunction and improve survival, functional status and quality of life, until a suitable heart is available or long-term device is implanted. 559

2 560 SECTION VII Heart Failure INDICATIONS FOR USE OF SHORT-TERM VENTRICULAR SUPPORT DEVICES 3 1. Patients with acute cardiogenic shock (INTERMACS level 1): The spectrum includes patients with acute myocardial infarction, myocarditis, acute on chronic heart failure and postcardiotomy patients. These patients may have end-organ failure, uncertain neurologic status and uncertain social support and thus not yet candidates for transplant or use of durable VADs. Cardiogenic shock after cardiotomy is treated with short-term VADs to bridge the patient to long-term durable LVAD or device explantation after myocardial recovery 4. Myocarditis occurs more in younger people and may result in acute cardiogenic shock and heart failure. Since the prospects of complete recovery are good, use of short-term VADs like extracorporal membrane oxygenation (ECMO) or CentriMag is indicated. Refractory ventricular arrhythmias associated with severe ventricular dysfunction are suitable indications for use of short-term LVADs. 2. Patients with chronic advanced heart failure Acute deterioration is a major indication for the use of short-term LVADs in chronic heart failure setting like NYHA class IIIB IV symptoms, frequent rehospitalizations for heart failure, unresponsiveness to medical therapies, recurrent/ refractory ventricular tachyarrhythmia, inotrope dependence, end-organ dysfunction due to low cardiac output, unresponsiveness to cardiac resynchronization therapy, peak oxygen consumption less than 14 ml/kg/min or a 6 min walk less than 300 m. Haemodynamic criteria for device implantation include systolic blood pressure lower than 80 mm Hg; mean arterial pressure lower than 65 mm Hg; cardiac index lower than 2.0 L/min/m 2 ; pulmonary capillary wedge pressure (PCWP) higher than 20 mm Hg; and systemic vascular resistance over 2100 dynes-s/ cm. Otherwise majority of chronic heart failure patients fall into destination therapy (DT) or BTT groups and are better managed with long-term durable LV assist devices. TYPES OF SHORT-TERM VENTRICULAR ASSIST DEVICES 4 PERCUTANEOUS SHORT-TERM VENTRICULAR ASSIST DEVICES 1. Intra-aortic balloon pump (IABP) 5 7 : This is the most common short-term support used. The mechanism of action of IABP involves inflation of a balloon in the descending thoracic aorta during diastole, which reduces left ventricular afterload, improves myocardial perfusion pressure, thus increasing coronary artery pressure and perfusion and reduces myocardial oxygen demand. IABP counter-pulsation is used today in a variety of clinical settings, including the cardiogenic shock associated with myocardial infarction, though studies have shown no reduction in mortality rates; the postcardiotomy shock; the mechanical complications of infarction, such as acute mitral regurgitation and ventricular septal defect; the postinfarction angina; and for the treatment of ventricular arrhythmias in the setting of ongoing ischaemia. IABP has also been used in critical haemodynamic support in the case of left ventricular failure, or during high-risk revascularization procedures with potential postcardiotomy weaning complications, as a costeffective BTD or bridge-to-bridge solution. Patients have faster postoperative mobility with subclavian or axillary artery access. Device failure may occur in the form of rupture of intraaortic balloon and vascular complications of IABP use include femoral artery rupture, pseudoaneurysm, descending aortic dissection and distal ischaemia. 2. Extracorporeal membrane oxygenation (ECMO) 8 : This system uses a centrifugal pump with an oxygenator and a heat exchanger in the circuit, resulting in complete cardiopulmonary bypass. A veno-venous ECMO is used for respiratory failure with preserved native heart function. The femoral vein and internal jugular vein are usually chosen. A veno-arterial (VA) ECMO is indicated for a failing heart. A VA-ECMO system can provide full circulatory support with over 4.5 L/min flow and rapidly improve tissue oxygenation. The advantages of ECMO are easy percutaneous insertion of the inflow and outflow cannulas, usually via femoral artery and vein. The major disadvantages are infection, bleeding and complications related to vascular access. The successful use of ECMO in the paediatric population has been well described. The outcome of ECMO for the treatment of cardiac failure in the adult population is more limited. Postcardiotomy ECMO support for elderly patients is associated with high peri-operative morbidity and mortality. 3. TandemHeart 9,10 : This device uses a centrifugal pump. The inflow cannula is introduced percutaneously via femoral vein into the right atrium

3 Chapter 67 Short-Term Ventricular Assist Devices as a Bridge to Decision/Recovery 561 and then into left atrium via a trans-septal puncture. The outflow cannula is placed in the femoral artery. The pump can deliver flow rates up to 5.0 L/min at a maximum speed of 7500 rpm. The clinical experience with TandemHeart has been more favourable than IABP in high-risk PCI and post-mi cardiogenic shock. It has shown to improve cardiac index, decrease in PCWP and support recovery of end-organ function. The disadvantage is the relatively complex mode of insertion involving trans-septal puncture. 4. The Impella (Abiomed) 7,11 : This is an intravascular micro-axial rotary pump that can be inserted across the aortic valve to provide forward blood flow from the left ventricle into the ascending aorta. The family of Impella devices include 2.5, CP, 5.0, LD and RP. The Impella 2.5 is a minimally invasive device inserted percutaneously through femoral artery across the aortic valve into the left ventricle, either under echocardiographic or fluoroscopic guidance. Impella 2.5 can provide partial circulatory support with flows up to 2.5 L/min and is relatively easy to implant. Initial results suggest that Impella 2.5 provides better haemodynamic support as compared to IABP in high-risk PCI and acute MI cases. The Impella 5.0/LD is inserted by a cardiac surgeon into ascending aorta or femoral artery or axillary artery. It is useful for treating acute cardiogenic shock or postcardiotomy shock, showing better survival benefit than with IABP usage. The Impella CP is an advanced version of Impella 2.5 and can provide flow rates up to 3.5 L/min. The Impella RP is designed for right ventricular (RV) support. In one study involving 18 patients with acute RV failure requiring ionotropes, IABP and nitric oxide, the Impella resulted in improved cardiac index, reduced central venous pressure (CVP) and in majority of patients, the Impella could be explanted within 7 days and had 72% 1-month and 50% 1-year survival rates HeartMate percutaneous heart pump is a catheter-based axial flow pump. It has a collapsible elastomeric impeller and Nitinol cannula and can be percutaneously inserted. The system can generate flows of 4 5 L/min. This pump is undergoing clinical trials. 6. The MAQUET Heart Lung Support (CAR- DIOHELP SYSTEM): This is the smallest and portable cardiopulmonary assist device useful in several life-threatening cardiac, pulmonary and combined cardiopulmonary conditions including postcardiotomy failure, BTD or recovery, pre- or post-transplant support, acute cardiac failure of different origins. It can be used for up to 30 days. SURGICAL SHORT-TERM VENTRICULAR ASSIST DEVICES 1. The Abiomed BVS 5000 (see ref 12) is a dualchambered, pneumatically driven, extracorporeal pump that can be used as univentricular or biventricular assist device. The device can deliver flows up to 6 L/min. The Abiomed AB5000 pump is a fully automated device and has a vacuum-assisted console. It allows more mobility for patients and duration of device support can be extended. 2. CentriMag : The CentriMag blood pump (Thoratec) is an extracorporeal centrifugal pump approved for short-term ventricular support. It operates without mechanical bearings or seals. The system combines the drive, magnetic bearing and the rotor function into a single unit. The rotor is magnetically levitated, enabling the device to rotate without friction and wear, without heat production. Trauma to blood and mechanical failure are minimized. The device can deliver flows up to 10 L/min with a priming volume of 31 ml. Thus CentriMag can be used to rescue patients with acute refractory cardiogenic shock. One retrospective study using CentriMag devices, ranging from 31 to 167 days, 74% patients were recovered or bridged, with a 1-year survival of 54%. CONTRAINDICATIONS FOR USE OF VENTRICULAR ASSIST DEVICES 16 Evaluation of heart failure severity, comorbidities and operative risks are crucial in patient selection for placing an LVAD for achieving good clinical results. The contraindications include severe unrecoverable neurologic injury and irreversible end-organ failure, especially renal failure and hepatic failure. Systemic sepsis in patients receiving LVAD implantation may cause a profound refractory vasodilatory state and device-related infections like device endocarditis. COMPLICATIONS Postoperative bleeding: Bleeding can be due to surgical causes or diffuse coagulopathy. Excessive bleeding may result in RV failure, infection and many adverse effects of multiple transfusions. Coagulopathy can result from dilutional thrombocytopenia and exposure to antiplatelet and antithrombotic agents.

4 562 SECTION VII Heart Failure Arrhythmias: Ventricular arrhythmias are especially common and could put patients at the risk of RV failure. Adjustment of pump speed and contact between inflow cannula and LV wall under 2D echo guidance is helpful. Use of an implantable cardioverter-defibrillator and antiarrhythmic medication are often indicated. Gastrointestinal bleeding and epistaxis: They are major sources of morbidity in patients with continuous flow VADs. Possible mechanisms include acquired Von Willebrand disease, gastrointestinal tract arteriovenous malformations due to reduced pulsatility and impaired platelet aggregation. Infection: Infection can manifest as a driveline, pocket, blood or device endocarditis. Sepsis occurs in 17% 28% and driveline infection occurs in 14% 27% of patients receiving presently available continuous flow VADs. Multisystem organ failure: The preoperative severity of organ dysfunction may lead to multisystem organ failure despite achieving a satisfactory haemodynamic status, due to a host of factors such as bleeding, sepsis, RV failure and other events. Thromboembolism: The blood-device interface of the VADs may lead to major thromboembolic events with continuous flow VADs in 5% 8% of cases. The key factors in development of stroke after VAD implantation are a previous history of stroke, persistent malnutrition and inflammation, increased severity of heart failure, and postoperative VAD infections. To avoid conversion to haemorrhagic stroke, anticoagulation and antiplatelet therapies may need to be discontinued. RV failure: For achieving a satisfactory left ventricular assist device (LVAD) flow, adequate RV function is necessary and significant RV dysfunction leads to poor outcomes in LVAD recipients. About 20% of patients may develop RV failure after continuous flow LVAD implantation and the probable mechanisms include intrinsic myocardial dysfunction and insufficient RV afterload reduction and complications after LVAD surgery such as renal failure, infection and bleeding. Additionally, patients with a continuous flow pump can develop RV failure from a significant leftward septal shift and distortion of RV geometry caused by LV oversucking. Aortic insufficiency (AI): Prolonged use of continuous flow VADs may lead to nonopening of aortic valve causing significant AI. This could be managed by optimization of pump speed under echocardiography to maintain pulsatility with intermittent aortic valve opening. Device malfunction: Minor device malfunctions can be tolerated but a major malfunction can be fatal. But the overall incidence of serious device malfunctions is decreasing due to advances in technology significantly over time. CONCLUSION The number of patients with advanced heart failure that has become unresponsive to conventional medical therapy is increasing rapidly. One of the most promising new alternatives to heart transplantation is use of VADs. Major technological advancements have enabled short-term VADs to assume a larger role in the treatment of heart failure over the last decade. Indications have broadened widely from its early uses. There are several considerations to keep in mind when deciding whether a patient is appropriate for temporary VAD. One must identify which device would suit a patient best, weighing the pros and cons of each method of support. Most patients requiring temporary support are acutely and critically ill, but an effort must be made to make decisions early when possible, ideally prior to a crash and burn (i.e. INTERMACS 1 profile) situation. There must also be an exit strategy prior to insertion of temporary VAD, as its role is primarily for the short term as a BTR, permanent support or transplantation 17,18. References 1. Rose, E. A., Gelijns, A. C., Moskowitz, A. J., Heitjan, D. F., Stevenson, L. W., Dembitsky, W., et al., Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) Study Group. (2001). Long-term mechanical left ventricular assistance for end-stage heart failure. New England Journal of Medicine, 345(20), Takeda, K., Takayama, H., & Naka, Y. (2016). Left ventricular assist devices and total artificial heart. In F. W Sellke, P. J. del Nido, & S. J. Swanson (Eds.), Sabiston and Spencer Surgery of the chest (9th ed., pp ). The Netherlands: Elsevier. 3. Miller, L. W., & Guglin, M. (2013). Patient selection for ventricular assist devices: A moving target. Journal of American College of Cardiology, 61, Shah, P, Pagani, F. D., Desai, S. S., Rongione, A. J., Maltais, S., Haglund, N. A., et al., Mechanical Circulatory Support Research Network. (2017). Outcomes of patients receiving temporary circulatory support before durable ventricular assist device. Annals of Thoracic Surgery, 103, Dietl, C. A., Berkheimer, M. D., Woods, E. L., Gilbert, C. L., Pharr, W. F., & Benoit, C. H. (1996). Efficacy and costeffectiveness of preoperative IABP in patients with ejection fraction of 0.25 or less. Annals of Thoracic Surgery, 62,

5 Chapter 67 Short-Term Ventricular Assist Devices as a Bridge to Decision/Recovery Mueller, H. S. (1994). Role of intra-aortic counterpulsation in cardiogenic shock and acute myocardial infarction. Cardiology, 84, Haneya, A., Philipp, A., Diez, C., Metterlein, T., Puehler, T., Hilker, M., et al. (2011). Successful use of temporary right ventricular support to avoid implantation of biventricular long-term assist device: a transcutaneous approach. ASAIO Journal, 57, Paden, M. L., Conrad, S. A., Rycus, P. T., Thiagarajan, R. R., & ELSO Registry. (2013). Extracorporeal Life Support Organization Registry Report ASAIO Journal, 59(3), Burkhoff, D., Cohen, H., Brunckhorst, C., & O Neill, W. W., TandemHeart Investigators Group. (2006). A randomized multicenter clinical study to evaluate the safety and efficacy of the TandemHeart percutaneous ventricular assist device versus conventional therapy with intraaortic balloon pumping for treatment of cardiogenic shock. American Heart Journal, 152(3), 469.e1 469.e Kar, B., Gregoric, I. D., Basra, S. S., Idelchik, G. M., & Loyalka, P. et al. (2011). The percutaneous ventricular assist device in severe refractory cardiogenic shock. Journal of the American College of Cardiology, 57(6), Lauten, A., Engström, A. E., Jung, C., Empen, K., Erne, P., Cook, S., et al. (2013). Percutaneous left-ventricular support with the Impella-2.5-assist device in acute cardiogenic shock: results of the Impella-EUROSHOCKregistry. Circulation Heart Failure, 6(1), Morgan, J. A., Stewart, A. S., Lee, B. J., Oz, M. C., & Naka, Y. (2004). Role of the Abiomed BVS 5000 device for short-term support and bridge to transplantation. ASAIO Journal, 50(4), John, R., Long, J. W., Massey, H. T., Griffith, B. P., Sun, B. C., Tector, A. J. et al. (2011). Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support. Journal of Thoracic and Cardiovascular Surgery, 141, Worku, B., Pak, S. W., van Patten, D., Housman, B., Uriel, N., Colombo, P., et al. (2012). The CentriMag ventricular assist device in acute heart failure refractory to medical management. Journal of Heart and Lung Transplantation, 31(6), Mohite, P. N., Zych, B, Popov, A. F., Sabashnikov, A., Sáez, D. G., Patil, N. P., et al. (2013). CentriMag shortterm ventricular assist as a bridge to solution in patients with advanced heart failure: Use beyond 30 days. European Journal of Cardiothoracic Surgery, 44, e310 e Kirklin, J. K., Naftel, D. C., Kormos, R. L., Stevenson, L. W., Pagani, F. D., Miller, M. A., et al. (2013). Fifth IN- TERMACS annual report: risk factor analysis from more than 6,000 mechanical circulatory support patients. Journal of Heart and Lung Transplantation, 32, den Uil, C. A., Akin, S., Jewbali, L. S., Dos Reis Miranda, D., Brugts, J. J., Constantinescu, A. A., et al. (2017). Short-term mechanical circulatory support as a bridge to durable left ventricular assist device implantation in refractory cardiogenic shock: A systematic review and meta-analysis. European Journal of Cardiothoracic Surgery, 52(1), doi: /ejcts/ezx Chetan, B., Patel, M. D., et al. division of Cardiology, Duke University Medical Center, Durham, North Carolina: A contemporary review of mechanical circulatory support

Mechanical Cardiac Support in Acute Heart Failure. Michael Felker, MD, MHS Associate Professor of Medicine Director of Heart Failure Research

Mechanical Cardiac Support in Acute Heart Failure Michael Felker, MD, MHS Associate Professor of Medicine Director of Heart Failure Research Disclosures Research Support and/or Consulting NHLBI Amgen Cytokinetics