Acute Hemodynamic Changes after Fontan Operation: An Experimental Study.

Abstract

Seven adult mongrel dogs with an average body weight of 11.3 kg were subjected to experimental Fontan operation in order to evaluate acute hemodynamic changes at the Fontan circulation. The Fontan circulation was established by occlusion of the tricuspid valve with tightening a purse-string suture which was placed around the valve under inflow occlusion and was passed through the anterior right atrial wall, and by connection with a 10 mm Gore-Tex graft between right atrium and pulmonary artery. When the Fontan circulation was established, aortic pressure and cardiac output (CO) decreased from 94.9 + 22.0 mmHg to 41.9 + 6.0 mmHg and 0.907±0.179 liter/min to 0.259±0.072 liter/min, respectively. There were no significant changes in heart rate and systemic vascular resistance between normal and the Fontan circulations. On the other hand, pulmonary vascular resistance (PVR) increased from 11.6±7.3 units in the normal circulation to 21.8± 13.0 units in the Fontan circulation. From this study it was concluded that main changes in hemodynamic parameters immediately after establishing the Fontan circulation were marked decrease in systemic arterial pressure and CO, and an increase in PVR. Therefore, one should consider a possibility of an increase in the PVR to the critical level when the Fontan operation was applied to patients with pulmonary hypertension. Fontan operation; tricuspid atresia ; pulmonary hypertension Fontan operation has been widely performed in many complex cardiac anomalies including tricuspid atresia, univentricular heart or hypoplasia of the right ventricle since the first report in 1971 (Fontan and Baudet). Although surgical indication for the Fontan operation had been tightly set by Fontan's Ten Commandment (Choussat et al. 1978) initially, recently the procedure has been challenged successfully in patients even with pulmonary hypertension greater than 20 mmHg of mean pulmonary artery pressure or with pulmonary vascular

Evolution in Experimental Fontan Circulation: A Review

“…The technique performed by Haneda, et al, as aforementioned, allowed pressure measurement in the RA, which reflects the increase in CVP. 14,17) The LA pressure manifests a minor decrease in our research, with a limited statistically non-significant outcome. Our results are in agreement with the experimental results of Haneda, et al, 14,17) whereas, according to the results of Nawa, et al, the LA pressure originally seems to increase, then decrease and finally sustain a normal value.…”

“…2,4,13,19) Mean arterial pressure decreased in most experimental protocols, 11,14,17) although Szabo, et al described a slightly non-significant increase. 13) The cardiac rhythm reduced in most experimental protocols, 10,12,17) even though it appeared to remain the same with a tendency to increase according to Szabo, et al 13) However, sinus rhythm is sustained. We attempted to prove if noted bradycardia was responsible for the low CO, but no linear relation was demonstrated between these two parameters.…”

“…13) The research of Haneda, et al and Kanakis, et al showed that after the establishment of Fontan circulation, the PAP was decreased. 14,17) However, Szabo, et al found a significant increase in PAP. 13) In the good Fontan circulation, the PAP is at best the same or lowers than the normal PAP.…”

“…16) The feasibility of experimental FO has been described either with CPB 8,12) or without CPB. 10,11,14,17) Nawa, et al, having constructed an appropriate Y shaped conduit from the end-to-side anastomosis of two separate tunnels, intravenously inserted and forwarded the upper ends of the conduit to the caval veins with the purse-string technique to the IVC and SVC. Having finally performed only one end-to-side anastomosis of the other end of the conduit to the pulmonary trunk, 10) while Kaku, et al conducted the procedure with the use of vascular clamps, allowing the end-to-side anastomosis of the graft to the caval veins.…”

“…It is noted that this experiment could be performed repeatedly from the physiologic status to Fontan circulation, since the tricuspid purse-string was driven through the RA via tourniquet. 17) In 1995, Mace, et al achieved total right heart exclusion in a dog model with full flow CPB in order to evaluate partial and complete right heart bypass. Through a right atriotomy, an atrial septal defect (ASD) and subsequently a channel diverting blood from both vena cava and CS into the left atrium (LA) was created.…”