Dynamic improvement in RV function is associated with favorable long-term outcome in patients with CHF [1]. Our study underscores the significance of preoperative RV dysfunction on postoperative worsening of RV dysfunction implantation of an LVAD (Figure 1
p = 0.002). Optimization of right heart function prior to implantation of an LVAD may reduce the risk of RV failure post-LVAD placement. In cases of severe right heart failure, simultaneous temporary mechanical support of the right heart may be indicated. Drakos et al. [6]. reported the preoperative risk factors for the development of RV failure after LVAD implantation in a series of 175 patients, which included a preoperative need for intra-aortic balloon counterpulsation, increased pulmonary vascular resistance, and destination therapy. We believe that a scoring system would be beneficial in predicting RV dysfunction, and the need for temporary RV mechanical support or permanent biventricular support [7], however, such a scoring system would require a standardized prospective study. A focused preoperative and postoperative evaluation of hemodynamic and echocardiographic data of right heart function can be used to create a scoring system to predict the RV dysfunction during the LVAD support.
During the LVAD support, the negative pressure in LV created by the LVAD causes deviation of interventricular septum towards the LV, which eliminates the septal contribution to right heart contractility. The severity of septal deviation may help in adjusting the LVD flow under echocardiography guidance and reduce the septal deviation towards the LV, which may then limit the RV dysfunction while on LVAD support. The RV function will eventually improve in days to weeks, postoperatively [8], however, in the acute stage, prevention of acute RV failure and its management is crucial for LVAD patients’ survival [8, 9]. Hendry et al. [10]. evaluated the role of septal shifting on RV dysfunction during the LVAD support. Septal shifting was documented as a change in LV shape index that was calculated using echocardiography findings. RV cardiac output decreased during LVAD support due to septal shifting towards the left ventricle, however, RV output was worse with increased RV afterload. This condition is tolerated by a normal functioning RV, however, in the presence of preoperative RV dysfunction and pulmonary hypertension, septal function is crucial for RV function, [10] and a deviation of the septum towards the LV will result in acute RV failure. Our study demonstrated that the patients with RV dysfunction have septal deviation towards the left ventricle (p = 0.02). The degree of septal shifting may predict the development of RV failure during LVAD support. This finding may help to adjust the flow following LVD placement and correct the septal deviation, which may then improve the RV dysfunction. A gradual increase of pump speed under echocardiography guidance can demonstrate the septal deviation and RV dysfunction immediately. An Adjustment of speed can be made under echocardiographic monitoring.
The importance of a competent TV on RV function has been underestimated. Potapov et al. 11 reported in a series of 54 patients that TV incompetence, RV dysfunction and shape, as well as right atrial dilation (short/long axis ratio >0.6), may help to predict the RV failure prior to LVAD placement [11]. In our series, the pre-existing TV regurgitation was associated with worsening RV function following LVAD implantation. However, this observation was not statistically significant (p = 0.29), which may be due to the small number of patients who had adequate echocardiographic evaluation of TV. Puwanant et al. [2]. emphasized the role of TVR in post-LVAD dysfunction of the RV. Lam et al. [4]. reported a small series of 21 patients that the RV function following LVAD implantation was better in the presence of a competent TV and was associated with an improved clinical condition of patients while on LVAD [4]. Preoperative evaluation of TV, RV function, shape, and geometry [11] may help to select patients who would benefit from biventricular support. In the presence of a significant TVR, we recommend a ring repair of the TV, which can be performed at the time of LVAD implantation.
In this study we also evaluated the pattern of adverse events causing readmission of LVAD patients to the hospital (Table 1). The adverse events in our patients are similar to reported data in the literature [12–18]. High risk of gastrointestinal bleeding (GIB) in LVAD patients has been reported in up to 40% of patients [13, 18]. We had increased risk of GIB in our patients, however we didn’t identify any specific risk factor. The work up for GIB in LVAD patients is the same as in other patients. The anticoagulation can be reversed until the bleeding source is identified and controlled. Hayes et al. [18]. suggested using intravenous octreotide in LVAD patients who suffered GIB. Knowledge of the most frequent adverse events, which may mandate readmission to the hospital in a timely fashion, may prevent serious complications.
Limitations of the study
This study has the common bias adherent to any retrospective study. Further, the study population was not uniform, and the etiology of heart failure was different. Some of the LVAD implantations were done up to 5 years ago and considering the improved techniques and advances in critical care, we should have fewer adverse events in coming years. The interobserver bias of clinicians who reviewed the echocardiograms is another limitation.
