High Transpulmonary Artery Gradient Obtained at the Time of Left Ventricular Assist Device Implantation Negatively Affects Survival After Cardiac Transplantation

Impact of diastolic pulmonary gradient and pulmonary vascular remodeling on survival after left ventricular assist device implantation and heart transplantation

BACKGROUND

The left ventricular assist devices (LVADs) are increasingly used for advanced heart failure as a bridge to heart transplantation or as a destination therapy. The aim of this study was to investigate the changes of diastolic pulmonary gradient (DPG), pulmonary vascular resistance (PVR) and transpulmonary gradient (TPG) after LVAD implantation and their impact on survival after LVAD and heart transplantation.

RESULTS

A total of 73 patients who underwent LVAD (HeartMate III) implantation between 2016 and 2022 were retrospectively studied. According to pre-LVAD catheterization, 49 (67.1%) patients had DPG < 7 mmHg and 24 (32.9%) patients had DPG ≥ 7 mmHg. The patients with a pre-VAD DPG ≥ 7 mmHg had higher frequencies of right ventricular (RV) failure (p < 0.001), RVAD insertion (p < 0.001), need for renal replacement therapy (p = 0.002), total mortality (p = 0.036) and on-VAD mortality (p = 0.04) with a longer ICU stay (p = 0.001) compared to the patients with DPG < 7 mmHg. During the follow-up period of 38 (12-60) months, 24 (32.9%) patients died. Pre-LVAD DPG ≥ 7 mmHg (adjusted HR 1.83, 95% CI 1.21-6.341, p = 0.039) and post-LVAD DPG ≥ 7 mmHg (adjusted HR 3.824, 95% CI 1.482-14.648, p = 0.002) were associated with increased risks of mortality. Neither pre-LVAD TPG ≥ 12 (p = 0.505) nor post-LVAD TPG ≥ 12 mmHg (p = 0.122) was associated with an increased risk of death. Pre-LVAD PVR ≥ 3 WU had a statistically insignificant risk of mortality (HR 2.35, 95% CI 0.803-6.848, p = 0.119) while post-LVAD PVR ≥ 3 WU had an increased risk of death (adjusted HR 2.37, 95% CI 1.241-7.254, p = 0.038). For post-transplantation mortality, post-LVAD DPG ≥ 7 mmHg (p = 0.55), post-LVAD TPG ≥ 12 mmHg (p = 0.85) and PVR ≥ 3 WU (p = 0.54) did not have statistically increased risks. The logistic multivariable regression showed that post-LVAD PVR ≥ 3 WU (p = 0.013), post-LVAD DPG ≥ 7 mmHg (p = 0.026) and RVF (p = 0.018) were the predictors of mortality after LVAD implantation. Pre-LVAD DPG ≥ 7 mmHg (p < 0.001) and pre-LVAD PVR ≥ 3 WU (p = 0.036) were the predictors of RVF after LVAD implantation.

CONCLUSIONS

Persistently high DPG was associated with right ventricular failure and mortality after LVAD implantation rather than after heart transplantation. DPG is a better predictor of pulmonary vascular remodeling compared to TPG and PVR. Further larger prospective studies are required in this field due to the growing numbers of patients with advanced heart failure, as possible candidates for LVAD implantation, and limitations of heart transplantation.

The Role of Serial Right Heart Catheterization Survey in Patients Awaiting Heart Transplant on Ventricular Assist Device

Current guidelines recommend serial right heart catheterization (RHC) to survey pulmonary hypertension in patients awaiting heart transplant. However, the role and impact of this surveillance is unclear in patients with a left ventricular assist device (LVAD). We reviewed our surveillance RHC protocol to determine whether useful data were obtained to justify the risks of serial invasive procedures (i.e., excessive bleeding). Between January 2015 and December 2018, 78 patients who received an LVAD as bridge-to-transplant (BTT) were included in this study. Routine RHC surveillance was performed every 6 months. Hemodynamic variables were retrospectively collected and reviewed. In 78 patients, 205 RHCs were analyzed. Median patient age was 54 years (IQR 46-61), and 64 (82%) were male. Thirty-six patients (46%) had pulmonary vascular resistance (PVR) ≤ 3 Wood units (WUs), and 42 patients (54%) had PVR > 3 WUs before LVAD. After LVAD implantation, mean PVR decreased by 36% from 3.8 ± 2.1 to 2.4 ± 1.1 WUs (p < 0.001) at 6 months and stabilized below 3 WUs at all post-LVAD time points. Four patients (11%) with pre-LVAD PVR ≤ 3 and 16 patients (38%) with a pre-LVAD PVR > 3 had PVR > 3 at least once during RHC survey. Of the 56 (76%) transplanted patients, six (40%) of 15 patients with a post-LVAD PVR >3 at least once developed moderate-to-severe right ventricular dysfunction. Although PVR significantly decreased after LVAD implant, PVR values fluctuated, particularly for those with pre-LVAD PVR > 3.0 WUs. Routine RHC appears valid for all BTT patients.

The Year in Cardiothoracic Transplantation Anesthesia: Selected Highlights from 2019

The highlights in cardiothoracic transplantation focus on the recent research pertaining to heart and lung transplantation, including expansion of the donor pool, the optimization of donors and recipients, the use of mechanical support, the perioperative and long-term outcomes in these patient populations, and the use of transthoracic echocardiography to diagnose rejection.

Physiology of the Assisted Circulation in Cardiogenic Shock: A State-of-the-Art Perspective

Mechanical circulatory support (MCS) has made rapid progress over the last 3 decades. This was driven by the need to develop acute and chronic circulatory support as well as by the limited organ availability for heart transplantation. The growth of MCS was also driven by the use of extracorporeal membrane oxygenation (ECMO) after the worldwide H1N1 influenza outbreak of 2009. The majority of mechanical pumps (ECMO and left ventricular assist devices) are currently based on continuous flow pump design. It is interesting to note that in the current era, we have reverted from the mammalian pulsatile heart back to the continuous flow pumps seen in our simple multicellular ancestors. This review will highlight key physiological concepts of the assisted circulation from its effects on cardiac dynamic to principles of cardiopulmonary fitness. We will also examine the physiological principles of the ECMO-assisted circulation, anticoagulation, and the haemocompatibility challenges that arise when the blood is exposed to a foreign mechanical circuit. Finally, we conclude with a perspective on smart design for future development of devices used for MCS.

Predicted heart mass-based size matching among recipients with moderate pulmonary hypertension: Outcomes and sex effect

BACKGROUND

There is a lack of evidence to guide appropriate donor sizing in recipients with moderate pulmonary hypertension (pHTN) awaiting heart transplantation (HTx). It is common practice to oversize donor hearts for such recipients to prevent post-operative right ventricular failure. Therefore, our objective was to determine if oversizing in pre-transplant moderate pHTN provides a survival advantage.

METHODS

The United Network for Organ Sharing database was analyzed to include HTx recipients from 1994 to 2016. Recipients were considered as having moderate pHTN if the pulmonary vascular resistance (PVR) was 2.5 to 5 Wood units (WU) or transpulmonary gradient (TPG) was 10 to 18 mm Hg. Heart size mismatch was determined using the predicted heart mass equations. A size mismatch of ≥15% in either direction was considered undersized or oversized, respectively. Ninety-day and 1-year survival were analyzed based on size matching via univariate and Cox regression analysis. Propensity matching was performed to specifically evaluate the effect of donor sex among male transplant recipients.

RESULTS

Among 29,441 HTx recipients, 10,666 had moderate pHTN by PVR criteria and 12,624 HTx patients had moderate pHTN according to TPG criteria. Among patients with a PVR of 2.5 to 5 WU, oversizing was not associated with lower mortality compared with matched hearts at 90 days (7.6% vs 7.4%; p = 0.75) and 1 year (12.1% vs 11.3%; p = 0.26). Conversely, undersizing the donor was associated with a higher 90-day (10.6% vs 7.6% vs 7.4%; p < 0.01) and 1-year (15.3% vs 12.1% vs 11.3%; p < 0.01) mortality than recipients receiving oversized or matched hearts, respectively. On Cox regression analysis, there was no benefit with oversizing at 90 days (hazard ratio [HR] 0.88; p = 0.23) and 1 year (HR 0.99; p = 0.90), whereas undersizing was associated with higher 90-day (HR 1.32; p = 0.02) and 1-year mortality (HR 1.23; p = 0.03) compared to size-matched controls. Among patients with moderate pHTN based on TPG of 10 to 18 mm Hg, neither undersizing nor oversizing was predictive of mortality at 90 days and 1 year according to Cox regression analysis. Propensity matching revealed that female-to-male transplantation had similar 1-year mortality to male-to-male transplantation, and there was no advantage to oversizing female donors for male recipients.

CONCLUSIONS

In this registry-based analysis, there was no benefit to oversizing donors for cardiac transplant recipients with moderate pHTN. Elimination of this restriction could increase the donor pool and reduce wait times for such recipients.