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

Abstract

AP. 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.00628.2008Little 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 Ϯ 0.80 WU) and systemic vascular resistances (18.4 Ϯ 7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39 Ϯ 0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n ϭ 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 ϭ Ϫ0.064 l ⅐ min Ϫ1 ⅐ WU Ϫ1 ) but not for the SV circulation (sensitivity ϭ Ϫ0.88 l ⅐ min Ϫ1 ⅐ WU Ϫ1 ). 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 (ϩ35%) and decreased preload (Ϫ12%) 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. mathematical modeling; cardiac function; congenital heart defects; magnetic resonance imaging THE FONTAN PROCEDURE, composing of connecting the systemic and pulmonary circulation in series via the total cavopulmonary connection (TCPC), is the primary palliative option for physiological correction of single ventricle (SV) congenital heart diseases (2, 3). Although postoperative survival is excellent, with some centers having a mortality of Ͻ1%, studies have repeatedly demonstrated poor functional outcome in survivors (15-18), including significantly reduced exercise capacity, diminished cardiac output (CO), and risks of heart failure (5, 10 -12, 16, 32, 35, 36, 40). Among all the parameters that come into play, decreased cardiac function in these patients seems to be one of the key players responsible for the poor functional outcome (26, 35). However, the impact of the surgically altered TCPC on cardiac function or functional outcome has not been well understood.Poor cardiac function in SV patients can be associated with many factors. For example, Fogel et al. (8) demonstrated that the presence of the lateral tunnel baffle restricted the motion of the atrioventric...

Ventricular‐Arterial Function and Coupling in the Adult Fontan Circulation

“…Ventricular efficiency varied inversely with HR in Fontan patients, but much less so in control patients consistent with previous studies in experimental systolic dysfunction33 and with modeling studies of the Fontan circulation 25. HR dependence of both Ees and ventricular efficiency in Fontan patients provide insight into the adverse impact of tachycardia on clinical status in Fontan patients.…”

“…Whereas elevated afterload has been described in pediatric Fontan patients and in its theoretical models,3, 24, 25 overall, vascular resistance, arterial compliance, and the sensitivity of afterload to HR3, 8 were similar in adult Fontan patients and controls. Of note, Ea sensitivity to increasing HR in Fontan patients was virtually the same as controls, suggesting a minor contribution of the pulmonary circulation as described in the lump parameter simulation model 25. Use of RAS antagonists and beta‐blockers were associated with more‐favorable vascular function, but causality cannot be assessed in this cross‐sectional study.…”

Pulsatile venous waveform quality in Fontan circulation-clinical implications, venous assists options and the future

“…The characterization of the Y-shaped connector and cannula assembly was performed on bench-top experiments using blood analog glycerine-water solution. The resistance was found to be 1.2 mmHg mL/min and 1.4 mmHg mL/min at 3 and 4 LPM, respectively, which is comparable with that of actual extra-cardiac Fontan connection (27). A tubing probe was placed around the pulmonary artery cannula.…”

Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study

“…The new parameters involved in the Fontan model are those used to describe the lateral atrial tunnel (or extracardiac conduit). These parameters are not derivable from the literature, although there exist a number of studies addressing energy loss or flow resistance associated with TCPC (32,85). We herein estimated the parameters from the geometric data of atrial tunnel or extracardiac conduit measured in Fontan patients (2,91).…”

“…However, the majority of existing studies focused on local hemodynamic phenomena, such as flow patterns, wall shear stress distribution in a cavopulmonary anastomosis, or associated energy loss (19,32,36,83,85,87). In studies where systemic hemodynamics was addressed, cardiovascular properties were usually fixed (55a), tuned to specific patients (40,54,63,64), or adjusted to represent certain physiological conditions (41,51).…”