Modified Fontan procedure, is the right atrial pump function necessary or not? Experimental approach using simulation model
Tamaki, S.; Kawazoe, K.; Yagihara, T.; Abe, T.
Nihon Kyobu Geka Gakkai 39(11): 2023-2028
1991
ISSN/ISBN: 0369-4739 PMID: 1774480 Document Number: 379107
The effect of pulsatile pulmonary flow and the characteristics of pulmonary arterial pressure (PAP) trace were examined using a model simulating the right heart following the modified Fontan procedure. An inlet overflow tank (preload), valveless axial pulsatile pump, Windkessel model (afterload), and an outlet overflow tank (left atrium) were connected in series. Standard conditions were: flow 2.00 l/m, with 12 mmHg preload, 3.0 wood units resistance and left atrial pressure at 6 mmHg. The pump rate was set at 80 bpm. Simulated PAP and pulmonary flow (PF) waves produced by this model closely resembled those obtained from patients who had undergone the modified Fontan procedure. Parameters except preload were fixed and changes in PF were examined at varying preload of 8, 12, 15 and 17 mmHg. At the various preload levels, PF increased to values greater than the PF for the same conditions in the non-pulsatile state. With a preload value of 8 mmHg, PF increased from 1.10 l/m (non-pulsatile) to a maximum of 1.55 l/min at a peak PAP of 14 mmHg. With a preload of 12 mmHg, the PF increased from 2.00 l/m (non-pulsatile) by 2.65 l/m at 19 mmHg peak PAP. A preload of 15 mmHg resulted in an increase in PF from 2.65 l/m (non-pulsatile) to 3.30 l/m at 22 mmHg peak PAP, and when the preload was 17 mmHg the PF increased from 3.15 l/m (non-pulsatile) to 3.80 l/m at 25 mmHg peak PAP. The afterload of this model was fixed so the increase in PF with pulsation suggests a decrease in resistance. Characteristics of PAP trace changing each parameter separately were examined under standard and fixed pulsatile conditions (peak PAP 20 mmHg). As preload was changed continuously from 8 mmHg to 17 mmHg, PF increased from 1.68 l/m to 3.70 l/m, then on PAP trace the pressure gradient between x and y valley was getting greater at higher preload level. Decrease of pulmonary arterial resistance made nothing to transform PAP trace except decrease of peak and mean PAP. In the event of compliance change, a lesser compliance lead flat v wave and a greater compliance resulted in decrease of a wave amplitude. Changes of each parameter made characteristic transformation on PAP trace.