The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise. Am J Physiol Heart Circ Physiol 295: H2427-H2435, 2008. First published October 17, 2008; doi:10.1152/ajpheart.00628.2008.-Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96 +/- 0.80 WU) and systemic vascular resistances (18.4 +/- 7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39 +/- 0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n = 16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output ( CO) dependence on TCPC resistance was negligible (sensitivity = -0.064 1.min(-1).WU-1) but not for the SV circulation (sensitivity = -0.88 1.min(-1).WU-1). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+ 35%) and decreased preload (- 12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology.