Predictive Value of Intraoperative Pulmonary Vascular Resistance in Liver Transplantation

Pulmonary Vascular Resistance to Predict Right Heart Failure in Patients Undergoing Left Ventricular Assist Device Implantation

Right heart failure (RHF) is associated with poor outcomes, especially in patients undergoing left ventricular assist device (LVAD) implantation. The aim of this study was to identify predictors of RHF after LVAD implantation. Of 129 consecutive patients (mean age 56 ± 11 years, 89% male) undergoing LVAD implantation, 34 developed RHF. Compared to patients without RHF, those with RHF required longer invasive mechanical ventilation and had longer intensive care unit and hospital stays (p < 0.01). One-year all-cause mortality was significantly higher in patients with versus without RHF after LVAD implantation (29.4% vs. 1.2%; hazard ratio 35.4; 95% confidence interval 4.5-277; p < 0.001). Mortality was highest in patients with delayed RHF after initial LVAD-only implantation (66.7%). Patients who did versus did not develop RHF had significantly higher baseline pulmonary vascular resistance (PVR; 404 ± 375 vs. 234 ± 162 dyn/s/cm5; p = 0.01). PVR > 250 dyn/s/cm5 was a significant predictor of survival in patients with RHF after LVAD implantation. These data confirm the negative impact of RHF on morbidity and mortality after LVAD implantation. Preoperative PVR > 250 dyn/s/cm5 determined using invasive right heart catheterization was an independent predictor of developing RHF after LVAD implantation, and of subsequent mortality, and could be used for risk stratification in the setting for deciding between single or biventricular support strategy.

The Prognostic Role of Right Ventricular Stroke Work Index during Liver Transplantation

Right heart-associated hemodynamic parameters including intraoperative pulmonary vascular resistance (PVR) were reported to be associated with patient survival after liver transplantation. We investigated whether intraoperative stroke work indexes of both ventricles could have a better prognostic value than PVR. We reviewed 683 cases at a tertiary care academic medical center. We collected intraoperative variables of baseline central venous pressure, baseline right ventricle end-diastolic volume, mixed venous oxygen saturation, intraoperative PVR and right and left ventricular stroke work indexes. Time-weighted means or area under the curve of intraoperative right and left ventricular stroke work indexes were calculated as exposure variables. One-year all-cause mortality or graft failure was our primary outcome. Cox proportional hazard regression analysis was performed to evaluate the association between exposure variables and one-year all-cause mortality or graft failure. Kaplan–Meier survival curve analysis of our primary outcome was performed for different time-weighted mean ventricular stroke work index groups. Cubic spline curve analysis was performed to evaluate the linear relationship between our exposure variables and primary outcome. Time-weighted mean right ventricular stroke work index was significantly associated with one-year all-cause mortality or graft failure (hazard ratio 1.21, 95% confidence interval (CI) 1.12–1.36, p < 0.001). However, there was no significant association between time-weighted mean left ventricular stroke work index, time-weighted mean PVR, PVR at the end of surgery and one-year mortality. Area under the curve of right ventricular stroke work index was also significantly associated with one-year mortality or graft failure (hazard ratio 1.24, 95% CI 1.15–1.37, p < 0.001). Kaplan–Meier survival curve analysis showed a significant difference in the survival between different mean right ventricular stroke work index groups (Log-rank test: p = 0.002). Cubic spline function curve showed the gradual increase in the risk of mortality with a positive slope with time-weighted mean right ventricular stroke work index. In conclusion, intraoperative elevated right ventricular stroke work index was significantly associated with poor patient or graft survival after liver transplantation. Intraoperative right ventricular stroke work index could be an intraoperative hemodynamic goal and prognostic marker for mortality after liver transplantation.

Intraoperative TOE guided management of newly diagnosed severe tricuspid regurgitation and pulmonary hypertension during orthotopic liver transplantation: a case report demonstrating the importance of reversibility as a favorable prognostic factor

Background

Tricuspid regurgitation (TR) and pulmonary hypertension (PHT) are highly dynamic cardiovascular lesions that may progress rapidly, particularly in the orthotopic liver transplantation (OLT) waitlist population. Severe TR and PHT are associated with poor outcomes in these patients, however it is rare for the two to be newly diagnosed intraoperatively at the time of OLT. Without preoperative information on pulmonary vascular and right heart function, the potential for reversibility of severe TR and PHT is unclear, making the decision to proceed to transplant fraught with difficulty.

Case presentation

We present a case of successful orthotopic liver transplantation (OLT) in a 48 year old female with severe (PHT) (mean pulmonary arterial pressure > 55 mmHg) and severe TR diagnosed post induction of anaesthesia. The degree of TR was associated with systemic venous pressures of > 100 mmHg resulting in massive haemorrhage during surgery and difficulty in distinguishing venous from arterial placement of vascular access devices. Intraoperative transoesophageal echocardiography (TOE) proved crucial in diagnosing functional TR due to tricuspid annular and right ventricular (RV) dilatation, and dynamically monitoring response to treatment. In response to positioning, judicious volatile anaesthesia administration, pulmonary vasodilator therapy and permissive hypovolemia during surgery we noted substantial improvement of the TR and pulmonary arterial pressures, confirming the reversibility of the TR and associated PHT.

Conclusion

TR and PHT are co-dependent, dynamic, load sensitive right heart conditions that are interdependent with chronic liver disease, and may progress rapidly in patients waitlisted for OLT. Use of intraoperative TOE and pulmonary artery catheterisation on the day of surgery will detect previously undiagnosed severe TR and PHT, enable rapid assessment of the cause and the potential for reversibility. These dynamic monitors permit real-time assessment of the response to interventions or events affecting right ventricular (RV) preload and afterload, providing critical information for prognosis and management. Furthermore, we suggest that TR and PHT should be specifically sought when waitlisted OLT patients present with hepatic decompensation.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0795-6) contains supplementary material, which is available to authorized users.