Right ventricular (RV) dysfunction is common in congestive heart failure [44]. Implantation of LVAD results in increased cardiac output and venous return, which can exacerbate severe RV failure [45]. In addition, unloading of the left ventricle can shift the interventricular septum to the left, decreasing the septal contribution to RV output [46, 47]. As many as 20–35 % of LVAD patients will develop severe RV failure and this directly increases mortality [48]. RV dysfunction after institution of MCS leads to longer lengths of stay, higher morbidity and mortality, and worse post-transplant outcomes [28, 49–51]. For this reason, assessment of RV function prior to LVAD implantation is essential.

An assessment of RV function should include an echocardiogram and invasive hemodynamics [19]. A low RV systolic pressure with elevated right atrial pressure and low RV stroke volume is a marker of severe RV impairment with decreased potential for reversibility [52]. Echocardiographic parameters that may be helpful in predicting post-LVAD RV failure include tricuspid annular plane systolic excursion (TAPSE) less than 1.5 cm, right to left ventricular end-diastolic diameter greater than 0.72, and RV stroke volume index [53]. It must be kept in mind that an RV that appears dysfunctional on echocardiogram may still be capable of generating high pulmonary pressures, therefore, invasive hemodynamics are a critical component of RV assessment. A pulmonary artery systolic pressure of less than 50 mmHg is thought to be associated with a high RV failure risk [48]. In addition, a RV stroke work index (RVSWI) of less than 450 mmHG × ml/m² is predictive of RV failure [48]. For patients with borderline RV function, an extended assessment period using a Swan-Ganz catheter in an ICU setting may be beneficial in determining if the patient can be managed with LVAD implantation alone [48].

Risk factor scores have been devised to help quantify the risk of RV failure as seen in Table 25.3. Fitzpatrick et al. from the University of Pennsylvania identified several risk factors for needing right ventricular assist device (RVAD) support. Independent predictors of RVAD support included cardiac index less than 2.2 L/m², RVSWI less than 250 mmHG × ml/m², severe RV dysfunction, serum creatinine greater than 1.9 mg/dL, previous cardiac surgery, and systolic blood pressure less than or equal to 96 mmHg. An important limitation of this study was that a small minority of the patients (less than 4 %) had continuous flow LVAD [54]. The University of Michigan risk score also identified several risk factors for RV failure. However, only 15 % of the devices in this study were continuous flow devices. Risk factors for RV failure in this study included vasopressor requirement, AST greater than 80 IH/L, bilirubin over 2.0 mg/dL, and serum creatinine greater than 2.3 mg/dL [48].

Kormos et al. carried out the largest study to date examining RV failure after implantation of a continuous-flow LVAD. In this study, numerous clinical, echocardiographic, and hemodynamic parameters were assessed. The University of Michigan RV failure score was also examined. Of the 484 patients in this study to receive the Heartmate-2 (HM-2) as a bridge to transplantation, 6 % required RVAD, 7 % required prolonged inotropic support, and 7 % required late initiation of inotropic support. The parameters found to predict RV failure on multivariate analysis included the need for mechanical ventilation, a central venous pressure/wedge pressure ratio greater than 0.63, and a blood urea nitrogen (BUN) over 39 mg/dL [55].

While mechanical circulatory support was once reserved for patients in New York Heart Association class IV heart failure in impending cardiogenic shock [29, 56], the benefits of implanting less critically ill patients is coming to light. Earlier device implantation, before end organ damage and right ventricular failure, leads to improved outcomes. Yet the estimated 5–10 % perioperative mortality [11, 57] for device implantation must be considered when implanting less severely ill patients. For example, a patient with a short estimated waiting time for cardiac transplantation in good clinical state might benefit from awaiting transplantation. However, for DT patients who reach inotrope dependence, LVAD implementation should not be delayed [58].

The two most common indications for LVAD placement are cardiogenic shock (INTERMACS level 1) and worsening symptoms in inotropic dependent patients (INTERMACS level 2). These two classes of patients account for 60 % of all MCS patients [10]. For stable, but inotropic-dependent patients (INTERMACS level 3), true dependence should be verified with a trial to withdraw inotropes. Once dependence has been verified, the patient should be considered for LVAD implantation as these patients have been shown to obtain the most benefit from institution of LVAD [58, 59].

For patients meeting INTERMACS levels 4–6 criterion, the timing of LVAD implantation remains controversial. Subgroup analysis of the REMATCH trial showed no survival benefit with implantation of LVAD in non-inotropic dependent patients. However, all clinical factors should be considered as up to 40 % of ambulatory heart transplantation candidates will deteriorate and require upgrade to high-urgency status or require emergency MCS [60]. For these non-inotrope dependent patients, cardiopulmonary testing is considered to be the best indicator of long-term outcomes [61, 62] and may be a useful tool in determining if patients will have a desirable outcome without LVAD support. Other risk scores such as the Heart Failure Survival Score [63] or the Seattle Heart Failure Risk Score [64] may also be useful adjuncts.

The total artificial heart (TAH) provides biventricular support and replaces the patient’s native ventricles and all four valves orthotopically. A large proportion of patients with LVAD will go on to develop right heart failure. The TAH can maintain these patients and provide complete replacement of the failing heart. The TAH has other additional advantages. It can be useful in patients whom LVAD and BIVAD is contraindicated, such as those with aortic regurgitation, cardiac arrhythmias, left ventricular thrombus, an aortic prosthesis, or an acquired ventricular septal defect [65, 66].

The largest study to date examining the use of the TAH demonstrated that in patients with irreversible biventricular failure, TAH implantation results in improved survival. Implantation of the TAH improved outcomes by providing immediate hemodynamic restoration and recovery of end-organ damage. This allowed a greater number of patients to reach cardiac transplantation [65, 66]. As experience with the TAH has increased, outcomes have improved [66]. Continued research and device improvement will lead to better results and decreased adverse events.