Kendall, Simon William Henry; (1996) Analysis of the effects of brain death on biventricular function and prolonged myocardial preservation, and the effect of complete atrioventricular transplantation on cardiac function in the recipient. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Brain stem death is confirmed prior to donation in clinical cardiac transplantation. This condition is associated with haemodynamic instability and eventual circulatory collapse. The effect of brain death on right ventricular function is unknown, as is its subsequent interaction with prolonged myocardial preservation. The technique for orthotopic cardiac transplantation, usually ventricular transplantation with atrioplasty, might be improved by complete atrioventricular implantation. The canine model was used to validate brain death (n = 13) whilst the optimal surgical method for implantation was assessed (n=40). Two-way variate analysis compared four experimental transplant groups for the main effects of brain death and four hour preservation, and the interaction between them (n=68). Rght ventricular function was also analysed post brain death when challenged with an increased pulmonary vascular impedance, as may occur in clinical transplantation (n=9). Systolic function was assessed for left and right ventricles using load independent analyses of pressure volume relationships; pre load independent recruitable stroke work (PRSW). Fourier analysis of pulmonary artery flow and pressure was utilised to calculate pulmonary vascular impedance and right ventricular hydraulic power. In addition atrial systole was analysed to compare surgical techniques of implantation. Complete transplantation conferred significant advantages in conserving sinus rhythm, right ventricular PRSW, and atrial systolic function. Intracranial balloon inflation was validated in causing brain stem death and these techniques were applied in remaining studies. Brain death significantly impaired PRSW by 21.2% and 29.4% for left and right ventricles respectively. Moreover an acute increase of pulmonary vascular impedance revealed that brain death significantly abolishes the right ventricle's reserve of hydraulic power. Four hours of preservation superimposes further injury to the right ventricle significantly reducing PRSW to 52% of baseline. This is reflected by the significant inotrope requirements to wean from cardiopulmonary bypass. Right ventricular function is significantly impaired by brain death. Prolonged preservation, for four hours, adds to this injury, suggesting future studies in prolonged myocardial preservation should use brain dead donors. Complete atrioventricular transplantation is superior to the standard technique although the clinical role for this method requires evaluation.

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