Multidisciplinary Approach to Cardiac and Pulmonary Vascular Disease Risk Assessment in Liver Transplantation

An Evaluation of the Evidence and Consensus Recommendations

Lisa B. VanWagner; Matthew E. Harinstein; James R. Runo; Christopher Darling; Marina Serper; Shelley Hall; Jon A. Kobashigawa; Laura L. Hammel

Disclosures

American Journal of Transplantation. 2018;18(1):30-42. 

In This Article

Portopulmonary Hypertension

PoPH is an uncommon condition involving the pulmonary circulation in 2%-6% of patients with underlying portal hypertension with or without underlying cirrhosis.[91–93] The definition of PoPH consists of 3 essential elements.[94]

  1. Mean pulmonary arterial pressure (MPAP) >25 mm Hg

  2. Pulmonary vascular resistance (PVR) >240 dynes·s per cm−5

  3. Pulmonary arterial occlusion pressure ≤ 15 mm Hg

PoPH increases morbidity and mortality due to associated right HF from pulmonary arterial hypertension. Approximately 51% of patients require hospitalization within 2 years of follow-up[95] with a median survival of 15 months and a 5-year survival of 14% in those not treated.[96] For individuals who receive pulmonary vasodilators, the median survival improves to 46 months with a 5-year survival of 45%.[96]

When present, PoPH is usually diagnosed as part of the LT evaluation during standard transthoracic echocardiogram (TTE). An estimated right ventricular systolic pressure >40–50 mmHg on TTE is an indication for right heart catheterization.[93] Only a right heart catheterization can adequately determine true pulmonary pressures as echocardiograms only offer estimates based on the tricuspid regurgitation velocity. Other TTE findings that raise suspicion for PoPH are an enlarged and dysfunctional right ventricle (RV) in the absence of valvular or left heart disease and significant tricuspid regurgitation.

Due to the high morbidity and mortality with PoPH, medical treatment with pulmonary vasodilators and even LT are therapeutic options. However, controversy exists over how aggressively PoPH patients should be treated and whether LT offers a survival advantage. Pulmonary vasodilator agents vary from oral phosphodiesterase 5 inhibitors (sildenafil and tadalafil) and endothelin receptor antagonists (bosentan, ambrisentan, and macitentan) to prostacyclins (epoprostenol, treprostinil, and iloprost). Patients receiving pulmonary vasodilators, especially prostacyclins, have improved outcomes over treatment-naïve individuals.[97–100] If a patient with PoPH responds adequately to pulmonary vasodilators, as defined by a MPAP <35 mm Hg and PVR <400 dynes·sec per cm−5, they may receive Mayo end-stage liver disease (MELD) exception points for liver allocation and proceed with LT.[101] There are emerging data that if patients can be safely transplanted, long-term survival can be achieved with reversal of pulmonary hypertension.[97,100,102]

Hemodynamic instability during surgery is a complex issue in PoPH. Adequate RV function, of which cardiac output is a surrogate, is likely the best predictor of operative survival.[96,99] Right HF may lead to cardiogenic shock and inotropic agents can be considered. Acute lowering of the PVR can be attempted with inhaled nitric oxide and/or prostacyclins. For intraoperative prostacyclin administration, either a change of dose or starting de novo, urgent consultation with the pulmonary hypertension team is strongly recommended. Judicious use of fluid resuscitation is necessary to prevent RV wall stress and RV dysfunction. In summary, a multidisciplinary team approach with experts in anesthesia and pulmonary hypertension is critical in the management of patients with PoPH.

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