Is partially reversible pulmonary hypertension a contraindication for heart transplantation?

Impact of pulmonary vascular resistances in heart transplantation for congenital heart disease

Congenital heart disease is one of the major diagnoses in pediatric heart transplantation recipients of all age groups. Assessment of pulmonary vascular resistance in these patients prior to transplantation is crucial to determine their candidacy, however, it is frequently inaccurate because of their abnormal anatomy and physiology. This problem places them at significant risk for pulmonary hypertension and right ventricular failure post transplantation. The pathophysiology of pulmonary vascular disease in children with congenital heart disease depends on their pulmonary blood flow patterns, systemic ventricle function, as well as semilunar valves and atrioventricular valves structure and function. In our review we analyze the pathophysiology of pulmonary vascular disease in children with congenital heart disease and end-stage heart failure, and outline the state of the art pre-transplantation medical and surgical management to achieve reverse remodeling of the pulmonary vasculature by using pulmonary vasodilators and mechanical circulatory support.

Heart transplantation in children with markedly elevated pulmonary vascular resistance: impact of right ventricular failure on outcome

BACKGROUND

Pulmonary hypertension causes increased morbidity and mortality in adults after heart transplantation. The effect of markedly elevated pulmonary vascular resistance (PVR) on post-transplant outcomes in children has not been well described.

METHODS

Outcomes were compared in a retrospective study between 58 children with an elevated PVR index (PVRI) ≥ 6 U/m(2) and 205 children with a PVRI < 6 U/m(2). Patients who did and did not respond to acute vasodilator testing and patients who underwent transplant before (pre-1995) and after (post-1995) the availability of inhaled nitric oxide (iNO) were compared.

RESULTS

The pre-transplant diagnoses, and cardiopulmonary bypass and donor ischemic times were similar between the high and low PVRI groups. High PVRI patients were older at transplant (12 ± 6.2 vs 8 ± 7.1 years, p = 0.002). The post-transplant inotrope score was higher in the high PVRI group (12 ± 12 vs 2 ± 2, p = 0.0001) and 1-year survival was worse (76% vs 81%, p = 0.03). The PVRI fell to < 6 U/m(2) with acute vasodilator testing in 21 of 49 (42%) high PVRI patients. RV failure occurred in 4 (19%) of the responders and in 14 (50%) of the non-responders (p = 0.037). One responder (5%) and 4 non-responders (14%) died of RV failure. In the period after 1995, the year iNO became clinically available, the select group of high PVRI patients who received iNO preemptively had a lower incidence of post-transplant RV failure than the group that did not receive preemptive iNO (13% vs 54%, p = 0.04).

CONCLUSIONS

Pre-transplant vasodilator testing identified patients at higher risk for RV failure. Patients who did not respond to vasodilator testing had an increased incidence of RV failure and death from RV failure. Preemptive use of iNO was associated with a decreased incidence of RV failure.

Medically Refractory Pulmonary Hypertension: Treatment With Nonpulsatile Left Ventricular Assist Devices

BACKGROUND

Severe pulmonary hypertension refractory to medical treatment is a contraindication to orthotopic heart transplantation in most centers. We report our experience in treating severe pulmonary hypertension with mechanical left ventricular unloading using implantable nonpulsatile left ventricular assist devices (LVAD) with continuous flow properties.

METHODS

In ten patients with severe pulmonary hypertension, refractory to medical treatment, an implantable nonpulsatile LVAD was placed for continuous mechanical left ventricular support. Pulmonary hemodynamics were assessed by right heart catheterization prior to and during LVAD implantation, and after orthotopic heart transplantation.

RESULTS

The mean (+/-SD) interval of nonpulsatile support was 182 (+/-118) days. Pulmonary artery pressure (mean +/- SD) significantly decreased from 42 +/- 13 to 24 +/- 5 mm Hg (p < 0.005), the transpulmonary gradient (mean +/- SD) decreased from 20 +/- 6 to 11 +/-5 mm Hg (p < 0.005), and the pulmonary vascular resistance (mean +/- SD) from 4.8 +/- 1.8 to 2.2 +/- 0.8 Wood units (p < 0.005) during an interval of one to six months of LVAD support. No significant increases in pulmonary artery pressure, transpulmonary gradient, and pulmonary vascular resistance were observed during an interval of three to six months after orthotopic heart transplantation.

CONCLUSIONS

This study supports that LVAD support and continuous nonpulsatile mechanical unloading of the left ventricle can reverse medically unresponsive pulmonary hypertension and render patients eligible for orthotopic heart transplantation.

Effect of Reversible Pulmonary Hypertension on Outcomes After Heart Transplantation

BACKGROUND

Conflicting data exist regarding the impact of reversible pulmonary hypertension (PHTN) on post-transplant (Tx) outcomes. In this study we sought to determine the influence of reversible PHTN on outcomes after Tx.

METHODS

We retrospectively reviewed the records of adult patients who underwent heart Tx from 1993 to 2002. Patients were grouped depending on their measured pulmonary vascular resistance (PVR). Group 1 patients had a pre-Tx pulmonary vascular resistance (PVR) of < 3 Wood units (WU). Patients with reversible PHTN, defined as pre-Tx PVR > or = 3 WU and reversing to < 3 WU either with sub-lingual or intravenous vasodilatory agents, were divided into two groups based on their PVR before the reversibility test (PVR: Group 2, 3 to 4.5 WU; Group 3, > 4.5 WU).

RESULTS

Records for 222 adult heart recipients were reviewed (Group 1, n = 171; Group 2, n = 35; Group 3, n = 16). Baseline clinical characteristics (age, gender, heart failure etiology, history of diabetes, ischemic time, donor age and gender) were similar in the three groups and the average follow-up was 58 months. One-month and 1-year mortality (Groups 1, 2 and 3: 2%, 0% and 13%; and 8%, 0% and 13%, respectively) did not differ significantly between groups. Actuarial mortality was assessed using Cox regression analysis, adjusted for age and gender, and no increased risk of death was demonstrated for patients with reversible PHTN (for Group 2: multivariate hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.17 to 1.32, p = 0.15; for Group 3: HR 0.98, CI 0.34 to 2.84, p = 0.97). No differences were observed between the three groups for various post-Tx events, such as hospital stay, ICU stay, extubation time, transfusions, acute allograft dysfunction, acute hepatic dysfunction, acute and chronic renal dysfunction, infections, neurologic complications, gastrointestinal complications and coronary allograft vasculopathy.

CONCLUSIONS

Reversible pulmonary hypertension is associated with similarly good post-transplant survival outcomes and morbidity, regardless of severity.

Left Ventricular Assist Devices as Bridge to Heart Transplantation in Congestive Heart Failure with Pulmonary Hypertension

Severe pulmonary hypertension (PH) has been considered a significant contraindication to cardiac transplantation. Ongoing clinical experience, however, has shown that temporary support using left ventricular assist devices (LVADs) in these patients can result in significant reductions in PH. A comprehensive review of the available literature regarding the use of LVADs in heart failure patients with PH was conducted. The existing literature to date supports the use of LVADs in heart failure patients with PH and demonstrates that significant reductions in PH in these patients can be achieved. This subsequently allows for safe and effective cardiac transplantation in patients who were previously excluded from this modality. For heart failure patients with severe PH, the use of LVADs can provide significant benefits by significantly reducing PH and allowing subsequent staged transplantation.

Pre-transplant reversible pulmonary hypertension predicts higher risk for mortality after cardiac transplantation

BACKGROUND

Pre-transplant fixed pulmonary hypertension is associated with higher post-transplant mortality. In this study, we assessed the significance of pre-transplant reversible pulmonary hypertension in patients undergoing cardiac transplantation.

METHODS

Overall, we studied 182 patients with baseline normal pulmonary pressures or reversible pulmonary hypertension, defined as a decrease in pulmonary vascular resistance (PVR) to < or =2.5 Wood units (WU), who underwent cardiac transplantation. Multiple recipient and donor characteristics were assessed to identify independent predictors of mortality.

RESULTS

The average duration of follow-up was 42 +/- 28 months. Forty patients (22%) died during the follow-up period. Baseline hemodynamics for alive vs dead patients were as follows: pulmonary artery systolic (PAS) 42 +/- 15 vs 52 +/- 15 mm Hg; PA diastolic 21 +/- 9 vs 25 +/- 9 mm Hg; PA mean 28 +/- 11 vs 35 +/- 10 mm Hg; transpulmonary gradient (TPG) 9 +/- 4 vs 11 +/- 7 mm Hg (all p < 0.05); total pulmonary resistance 7.7 +/- 4.8 vs 8.8 +/- 3.2 WU (p = 0.08); and PVR 2.3 +/- 1.5 vs 2.9 +/- 1.6 WU (p = 0.06). In an unadjusted analysis, patients with PAS >50 mm Hg had a higher risk of death (odds ratio [OR] 5.96, 95% confidence interval [CI] 1.46 to 19.84 as compared with PAS < or =30 mm Hg). There was no significant difference in survival among patients with baseline PVR <2.5, 2.5 to 4.0 or >4.0 WU, but patients with TPG > or =16 had a higher risk of mortality (OR 4.93, 95% CI 1.84 to 13.17). PAS pressure was an independent predictor of mortality (OR 1.04, 95% CI 1.02 to 1.06). Recipient body mass index, history of sternotomy; and donor ischemic time were the other independent predictors of mortality.

CONCLUSION

Pre-transplant pulmonary hypertension, even when reversible to a PVR of < or =2.5 WU, is associated with a higher mortality post-transplant.