Pulmonary hypertension: considerations in the liver transplant candidate

Effects of Dobutamine on Right Ventricular Function and Pulmonary Circulation in Pulmonary Hypertension During Liver Transplantation

INTRODUCTION

In the setting of orthotopic liver transplantation (OLT), pulmonary hypertension (PH) affects right ventricular (RV) function. When RV failure occurs, reducing RV afterload, optimizing RV preload, and preserving coronary perfusion through maintenance of systemic blood pressure are the primary goals of intraoperative treatment.

PATIENTS AND METHODS

To verify the effect of dobutamine on RV function and RV-arterial coupling, we compared a group of 9 cirrhotic patients with mild PH treated with OLT to a group of 20 patients with normal mean pulmonary artery pressure (MPAP). All patients received dobutamine (5-10 microg/kg/min) to maintain a cardiac index (CI) >3 L/min/m(2), during the anhepatic phase. Hemodynamic profile, using a pulmonary artery catheter, was performed before and during dobutamine infusion, studying MPAP, CI, and RV end-diastolic volume index (RVEDVI). RV stroke work index (RVSWI), RV end-systolic elastance (Ees), pulmonary effective elastance (Ea), and RV-arterial coupling efficiency as the Ees/Ea ratio were also calculated.

RESULTS

RV contractility (Ees and RVSWI) and afterload (Ea) were significantly higher among the PH group. In both groups, all the studied variables improved with dobutamine: RV contractility increased, afterload decreased, and thus Ees/Ea coupling markedly increased.

CONCLUSION

Cirrhotic patients with mild PH who were undergoing OLT still have a reserve of RV contractile performance and pulmonary vasodilation.

Liver transplantation in the UK

INTRODUCTION

This paper provides a review of the practice of liver transplantation with the main emphasis on UK practice and indications for transplantation.

REFERRAL AND ASSESSMENT

This section reviews the process of referral and assessment of patients with liver disease with reference to UK practice.

DONOR ORGANS

The practice of brainstem death and cadaveric organ donation is peculiar to individual countries and rates of donation and potential areas of improvement are addressed.

OPERATIVE TECHNIQUE

The technical innovations that have led to liver transplantation becoming a semi-elective procedure are reviewed. Specific emphasis is made to the role of liver reduction and splitting and living related liver transplantation and how this impacts on UK practice are reviewed. The complications of liver transplan-tation are also reviewed with reference to our own unit. Immunosuppression:The evolution of immunosuppression and its impact on liver transplantation are reviewed with some reference to future protocols.

RETRANSPLANTATION

The role of retransplantation is reviewed.

OUTCOME AND SURVIVAL

The results of liver transplantation are reviewed with specific emphasis on our own experience.

FUTURE

The future of liver transplantation is addressed.

Orthotopic liver transplantation in a patient with severe portopulmonary hypertension

Liver transplantation in patients with severe portopulmonary hypertension (PPH) has been associated with mortality rates in the range of 70% to 80%. Preoperative long-term epoprostenol therapy reverses pulmonary hypertension and may be a valuable possibility to reduce mortality in patients with severe PPH undergoing orthotopic liver transplantation. We want to report a patient with severe PPH, who was treated with intravenous epoprostenol for an 8-month period, after which pulmonary vascular resistance had decreased from 12 to 3 Wood units. Nevertheless, the patient developed intractable perioperative right heart failure necessitating transient mechanical circulatory support. The patient was weaned from mechanical circulatory support, but died from another episode of acute right heart failure after 28 days. Complicated liver transplantation associated with major cardiovascular stress is obviously not tolerated in patients with severe portopulmonary hypertension even after preoperative long-term epoprostenol therapy.

Progressive portopulmonary hypertension after liver transplantation treated with epoprostenol

Portopulmonary hypertension (PPHTN) is an uncommon complication of advanced liver disease. Epoprostenol has been effective in the treatment of PPHTN and has been used as a bridge to orthotopic liver transplantation (OLT). The role of OLT in the reversal of PPHTN is unclear. We report a case of severe PPHTN (mean pulmonary artery pressure of 45 mm Hg) that progressed after OLT. Acute dosing with epoprostenol improved the pulmonary vascular resistance by 55% and the cardiac index by 134%. Hemodynamic and symptomatic improvements were maintained after 18 months of long-term treatment with epoprostenol. This is the first reported case of a successful favorable outcome after treatment for progressive PPHTN after OLT. Our case report complements previous reports by highlighting the potential effective use of epoprostenol as a definitive treatment for PPHTN.

Improvement of cardiac output and liver blood flow and reduction of pulmonary vascular resistance by intravenous infusion of L-arginine during the early reperfusion period in pig liver transplantation

BACKGROUND

The release of liver arginase after orthotopic liver transplantation (OLT) causes a deficiency of L-arginine and nitrite in the plasma. This deficiency is possibly related to pulmonary hypertension and reduced hepatic blood flow, which are commonly observed in the immediate reperfusion period. The aim of this study was to evaluate the impact of L-arginine supplementation on metabolic and hemodynamic parameters during liver reperfusion after OLT in pigs.

METHODS

Thirteen pig OLTs (control group, n=6; arginine group, n=7) were performed by a standard technique. Cold ischemic time was 20 hr. L-Arginine was infused at a dosage of 500 mg/kg body weight into the donor pigs (30 min before liver explantation) and also into the recipients (over a period of 3 hr from the beginning of the reperfusion period). At the end of the experimental study, the pigs were killed with an overdose of potassium.

RESULTS

In the control group, liver revascularization increased plasma arginase concentrations (+615%) and reduced plasma levels of L-arginine (-87%), nitrite (-82%), and nitrate (-53%). Infusion of L-arginine increased plasma levels of L-arginine from 94+/-21 micromol/L to 1674+/-252 micromol/L (P<0.001), L-ornithine from 46+/-8 micromol/L to 2215+/-465 micromol/L (P<0.001), and L-citrulline from 58+/-8 micromol/L to 116+/-34 micromol/L (P<0.001), but had no effect on plasma levels of nitrite and nitrate. Administration of L-arginine in the donor pigs did not produce any systemic or organ-specific hemodynamic alterations. Infusion of L-arginine into the recipient pigs improved cardiac performance (increase in heart rate [+61%, P=0.017] and cardiac index [+53%, P=0.005], reduction in pulmonary capillary wedge pressure [-54%, P=0.014]). Moreover L-arginine infusion increased oxygen consumption (+65%, P=0.003), reduced pulmonary vascular resistance index (P=0.001), stimulated portal venous blood flow (P=0.014), and elevated body temperature during the reperfusion period (P=0.007).

CONCLUSIONS

From these data, we conclude that the infusion of L-arginine during OLT improves the hemodynamic performance of the heart, lung, and liver.