PULMONARY VASCULAR IMPEDANCE AND RECIPIENT CHRONIC PULMONARY-HYPERTENSION FOLLOWING CARDIAC TRANSPLANTATION

Study objectives: Recipient chronic pulmonary hypertension (CPH), seco ndary to long-standing congestive heart failure, represents a signific ant risk factor for right ventricular (RV) dysfunction following ortho topic cardiac transplantation (TX). This study was designed to charact erize the changes occurring in pulmonary hemodynamics, pre-TX and post -TX, using Fourier analysis, a canine model of bicaval TX, and monocro taline pyrrole (MCTP)-induced recipient CPH. Design: Prospective, cont rolled study. Setting: Experimental laboratory. Participants: Twenty a dult male mongrel dogs (23 to 26 kg). Interventions: Recipients underw ent pulmonary artery injection of 3 mg/kg MCTP 4 months pre-TX. On the day of TX, donor hearts were instrumented with an ultrasonic flow pro be and micromanometers. Harmonic derivation of functional data was ach ieved with Fourier analysis. Measurements and results: At the time of TX, significant increases were observed in the mean pulmonary artery p ressure and pulmonary vascular resistance of recipient animals in comp arison to donors, which were further significantly increased following the termination of cardiopulmonary bypass. Significant increases were also observed in the input resistance, characteristic impedance, and RV hydraulic power post-TX compared to pre-TX, and occurred in associa tion with a significant decrease in the transpulmonary efficiency. Con clusions: Zn the setting of MCTP-induced recipient CPH donor hearts we re exposed to significant alterations in cardiopulmonary hemodynamics following bicaval TX. Pulmonary blood flow is maintained by a signific antly higher energy expenditure by the RV, but at a lower level of eff iciency. This experimental model may provide a useful means by which t o evaluate therapeutic options to better manage cardiopulmonary hemody namics in order to prevent RV failure following TX in the setting of r ecipient CPH.