Rest and exercise hemodynamics after the Fontan procedure

The effects of rate responsive pacing on exercise performance in the postoperative univentricular heart

Following the Fontan operation for definitive palliation of the univentricular heart, sinus node dysfunction, and/or atrioventricular block requiring pacemaker therapy is common. In previous studies ventricular rate responsive pacing (VVI,R) resulted in improved exercise performance over VVI pacing in anatomically normal hearts with either sinus node disease or atrioventricular block. In this study, the usefulness of both VVI,R and DDD,R pacing are evaluated in the postoperative univentricular heart following the Fontan operation. Eight postoperative Fontan patients with sinus node disease or atrioventricular block underwent exercise testing using a treadmill protocol. Six patients had single chamber ventricular pacemakers and two patients had dual chambered rate responsive pacemakers. Median age at exercise testing was 14 years. Patients were tested in the VVI, VVI,R, and DDD,R modes acting as their own controls. Heart rate, work rate, oxygen consumption, and respiratory exchange ratio were monitored continuously. Heart rate was significantly increased in the rate responsive modes compared to the VVI mode. In spite of the significant increase in heart rate, there was no change in maximal work rate or oxygen consumption. There was also no significant change in oxygen consumption at ventilatory anaerobic threshold. From these data we would conclude that VVI,R pacing in postoperative univentricular hearts does not result in improved exercise performance and that further study with DDD,R pacing is needed to determine its usefulness in this group of patients.

Ventricular performance before and after Fontan repair for univentricular atrioventricular connection: angiographic and radionuclide assessment

OBJECTIVES

This study was designed to evaluate changes in ventricular volume, mass and cardiac function before and after creation of an atrial to pulmonary connection in patients with a univentricular atrioventricular connection.

BACKGROUND

Intact systolic and diastolic performance is critical for successful establishment of an atrial dependent circulation, and few studies are available comparing cardiac performance before and after creation.

METHODS

With the use of radionuclide blood pool imaging and ventricular cineangiography, 54 patients (mean age 6.4 +/- 3.4 years) were studied. Twenty-eight patients were investigated preoperatively and 36 greater than 1 year after repair and compared with a control population.

RESULTS

Before operation, end-diastolic volume and wall mass were significantly increased compared with those of control subjects; however, the mass/volume ratio was normal (1.08 +/- 0.31 g/ml for the preoperative group; 0.97 +/- 0.19 for control subjects). Although end-diastolic volume returned to normal after the procedure, wall mass remained elevated and contributed to an elevated mass/volume ratio (1.20 +/- 0.38 g/ml). After the procedure, systemic vascular resistance index was significantly elevated compared with that before surgery or with that of control subjects (1,199 +/- 373, 2,120 +/- 645, 1,556 +/- 275 dynes.s.cm-5.m2: pre- and postrepair and control subjects, respectively). Radionuclide studies demonstrated that preoperative ejection fraction (52 +/- 9, 50 +/- 9, 60 +/- 8%), peak ejection (2.58 +/- 0.66, 2.95 +/- 0.81, 3.73 +/- 0.70 EDV/s) and peak filling rates (2.84 +/- 0.75, 2.75 +/- 0.79, 3.84 +/- 0.51 end-diastolic volumes [EDV/s]) were significantly reduced compared with those of control subjects and remained so after surgery.

CONCLUSIONS

These data suggest that systolic and diastolic function is depressed preoperatively in these patients, remains unchanged after the creation of an atrial-dependent circulation and is associated with an increased systemic vascular resistance. Long-term issues addressing preservation of cardiac function need to be prospectively studied.

The modified Fontan procedure: physiology and anesthetic implications

The modified Fontan operation has gained wide acceptance as a functional corrective procedure for patients with CHD with single ventricle physiology. Long-term survival and palliation of symptoms are excellent with most patients able to lead normal lives. The absence of a pulmonary contractile ventricle means that the single ventricle is responsible for perfusion of both the pulmonary and systemic circulations. Elevated systemic venous pressure is required to overcome PVR and this state of systemic venous hypertension has a significant impact on the anesthetic and postoperative care of these patients.

Effect of right ventricular anatomy on the cardiopulmonary response to exercise. Implications for the Fontan procedure

Incorporation of the right ventricle (RV) into the pulmonary circulation of patients with tricuspid atresia undergoing a Fontan procedure has been advocated. The consequences of this approach on the exercise function of these patients was studied by examining the effects of progressive and steady-state bicycle exercise tests performed by 11 patients with right atrial (RA)-RV Fontan anastomoses, seven patients with RA-pulmonary artery (PA) Fontan anastomoses, 13 patients after repair of tetralogy of Fallot, and 34 normal control patients. All patients were in New York Heart Association class I. The exercise function of the patients undergoing RA-RV and RA-PA Fontan procedures were similar. The achieved peak work loads 60% and 67% of control and peak oxygen consumptions 60% and 64% of control, respectively. Both groups also displayed excessive ventilation, elevated dead space/tidal volume ratios, and depressed cardiac output during steady-state exercise. In contrast, tetralogy of Fallot patients achieved peak work loads and oxygen consumptions 83% of control and maintained normal cardiac outputs and dead space/tidal volume ratios during steady-state exercise. These results suggest that the presence of an RV within the pulmonary circulation of the Fontan patient does not result in improved exercise function. This may be due to the development of obstructive gradients across the RA-RV conduits during exercise or to the RV's negative effect on left ventricular compliance. Moreover, in contrast with the postoperative tetralogy of Fallot patient, the hypoplastic RV of tricuspid atresia may not have sufficient myocardium to assume the active pumping function required by exercise.

Exercise responses in patients with congenital heart disease after Fontan repair: patterns and determinants of performance

After a Fontan repair for congenital heart disease, 42 patients underwent graded supine bicycle exercise tests at levels relevant to normal daily activities. Results were compared with those of 28 age-matched normal control subjects. At rest, the cardiac index, stroke index and systolic blood pressure were comparable in both groups, but increases with exercise were smaller in the patients with a Fontan circulation. The heart rate at rest was higher in the Fontan group, but this difference disappeared as soon as exercise started. To determine whether there are limitations intrinsic to the Fontan circulation at these levels of exercise, the 10 best performers were compared with 10 age-matched control subjects; no differences were found in cardiac index, stroke index, heart rate or blood pressure at any exercise level. Analysis of the determinants of cardiac output showed that at the other end of the spectrum poor performance after a Fontan operation did not result from inadequate levels of heart rate, but from an inability to increase or maintain stroke volume. Multivariate analysis demonstrated that impairment of ventricular contractility, only when severe, predicted limited performance. There was no evidence of increased afterload, particularly in the poor performers. Therefore, ventricular filling, which is determined primarily by the pulmonary vascular bed, appears to be a major determinant of functional result after a Fontan repair.

Outcome after a "perfect" Fontan operation

A study was undertaken to determine the early and long-term outcomes dictated by the Fontan state per se (a state in which the force driving pulmonary blood flow is solely or largely a residue, in the systemic venous pressure, of the main ventricular chamber's contractile force) and the transition (by surgery) to it from the state of congenital heart disease under optimal conditions (after a "perfect" Fontan operation). The primary study design used a solution of a multivariate risk factor equation for death, by which survival rate under optimal conditions was predicted to be 92%, 89%, 88%, 86%, 81%, and 73% at 1 month, 6 months, and 1, 5, 10, and 15 years, respectively, after the Fontan operation. The hazard function (instantaneous risk of death at each moment in time after the operation) had an early rapidly declining phase of hazard that at about 6 months began to give way to a late hazard phase, which was rising by about 6 years after surgery. A secondary study design, using the theory of competing risks, yielded survival and hazard function information very similar to that of the primary study design. The functional capacity of the patients as expressed by New York Heart Association class was less, the longer the period of follow-up. No risk factors (other than older age at time of surgery) were found for the late decline in survival or the decline in functional status. The inference is that the premature decline in survival and functional status and the late rise in hazard function are from the Fontan state per se and that the Fontan operation is, therefore, palliative but not curative.

The modified Fontan operation for children less than 4 years old

Of 500 patients who had a modified Fontan operation at this institution between 1973 and 1987, 54 (33 boys and 21 girls) were less than 4 years old. This retrospective study related preoperative clinical and hemodynamic data to subsequent survival. Twenty patients less than 4 years old had tricuspid atresia, 13 had double inlet ventricle and 21 had other complex heart defects. There were 14 early deaths (less than 30 days after operation) and 6 late deaths. Multivariate analysis of survival for the entire group of 500 patients revealed the following factors to be significantly associated with poorer survival: absence of tricuspid atresia (p = 0.011), asplenia (p less than 0.001), age less than 4 years at operation (p = 0.042), atrioventricular valve dysfunction (p = 0.017), early calendar year of operation (p less than 0.001) and the presence of either one or more of the following: left ventricular ejection fraction less than 60%, mean pulmonary artery pressure greater than 15 mm Hg and pulmonary arteriolar resistance greater than 4 U.m2 (p less than 0.001). On the basis of this study of 500 patients, age less than 4 years at operation appears to be an independent risk factor for poorer survival after the modified Fontan operation.

Exercise tolerance and cardiorespiratory response to exercise before and after the Fontan operation

To determine the effect of the Fontan operation on exercise tolerance and cardiorespiratory response to exercise, we compared the preoperative and postoperative responses to graded exercise to maximal effort in 20 patients who underwent a modified Fontan procedure. The mean interval between preoperative and postoperative exercise testing was 1.8 years. Postoperatively, total work performed, duration of exercise, and maximal oxygen uptake were significantly increased. Although cardiac output increased during exercise, the response was subnormal, and stroke volume was unchanged. The heart rate and systolic blood pressure during maximal exercise were not significantly changed from preoperative values, but the diastolic blood pressures during rest and maximal exercise were significantly increased postoperatively. Systemic arterial blood oxygen saturation increased after the modified Fontan operation, but during exercise, a mild but significant desaturation occurred (93% compared with 90%). The ventilatory equivalent for oxygen decreased toward normal during exercise. The respiratory rate and oxygen consumption during resting remained unchanged from preoperative values. For this subset of patients, these data indicate that exercise tolerance improves, cardiac output and stroke volume responses to exercise are subnormal, and ventilatory response to exercise decreases toward normal after the modified Fontan operation.

When should the hypoplastic right ventricle be used in a Fontan operation? An experimental and clinical correlation

Eight anesthetized dogs underwent closure of the tricuspid valve and a Fontan procedure, and the right ventricular cavity was reduced in stepwise fashion. There was an increase in right atrial pressure from 9.3 +/- 2.2 to 14.1 +/- 2.4 mm Hg (p less than 0.001), a decrease in pulmonary artery pulse pressure from 10.8 +/- 2.2 to 6.8 +/- 2.2 mm Hg (p less than 0.01), and a decrease in cardiac index from 2.7 +/- 0.3 to 2.2 +/- 0.2 L/min/m2 (p less than 0.001) when the ventricular size was dropped from 50% to 25% of normal. The difference between mean pulmonary artery pressure and mean right atrial pressure, which reflects the positive stroke work index of the ventricle, disappeared once the right ventricular cavity was reduced to 25% of normal (15.0 +/- 6.1 versus 14.1 +/- 2.4 mm Hg; p = not significant). Experimental results were correlated with postoperative catheterization data from 19 patients with tricuspid atresia who had the Fontan operation. Mean right atrial pressure was 18 +/- 4.6 mm Hg and cardiac index was 2.35 +/- 0.65 L/min/m2 in patients with a direct atrium-pulmonary artery anastomosis or an atrioventricular anastomosis with a right ventricular cavity less than 30% of normal versus 13 +/- 3.2 mm Hg and 3.42 +/- 0.46 L/min/m2 for those with an atrioventricular connection and a right ventricular cavity greater than 30% of normal (p less than 0.05 and p less than 0.02, respectively). The right ventricle enlarged from 27% +/- 6% of normal preoperatively to 35% +/- 10% of normal on follow-up (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of tricuspid regurgitation in hypoplastic left-heart syndrome

Palliation of hypoplastic left-heart syndrome involves use of the morphologic right ventricle as the systemic ventricle and the tricuspid valve (in cases of mitral atresia/stenosis) or the common atrioventricular valve (in cases of malaligned atrioventricular canal) as the systemic atrioventricular valve. To determine the relationship between tricuspid or common atrioventricular valve function and the ultimate outcome of palliative surgery, 100 patients with hypoplastic left-heart syndrome were evaluated preoperatively by Doppler echocardiography to determine the degree of tricuspid regurgitation. These patients were then followed serially to assess changes with time in the functional status of the tricuspid or common atrioventricular valve and to determine the correlation of tricuspid or common atrioventricular valve regurgitation with survival. We discovered that tricuspid or common atrioventricular valve regurgitation is common in hypoplastic left-heart syndrome. Thirty-seven percent of the patients had mild, 13% had moderate, and 3% had severe tricuspid or common atrioventricular valve regurgitation on their preoperative Doppler echocardiograms. Throughout the first 2 postoperative years most patients had no significant change in the degree of tricuspid or common atrioventricular valve regurgitation when findings were compared to those of the preoperative echocardiogram. Patients with moderate or severe tricuspid or common atrioventricular valve regurgitation preoperatively had a significant reduction in their survival when contrasted with patients with no or mild atrioventricular valve regurgitation. We therefore conclude that tricuspid or common atrioventricular valve competence is a significant factor in long-term survival after palliative surgery for hypoplastic left-heart syndrome. This function, however, appears to be unaffected by palliation and remains relatively constant over the first 2 postoperative years.

Radionuclide evaluation of lung perfusion after the Fontan procedure

Lung perfusion was evaluated in 19 patients in whom a Fontan operation had been performed at a mean age of 3.7 years. First pass and equilibrium data were acquired during the lung particle perfusion scan 0.5 to 7.9 years (mean 3.7 years) following the Fontan procedure. Abnormalities of lung perfusion were documented in 8 patients. Minimal underperfusion of small areas of either right or left lung were noted in 4 patients, while the remaining 4 had evidence of major perfusion defects, involving both lungs. The perfusion defects were localized, in the majority of cases, on the side where a palliative procedure had been performed before the Fontan operation: it is of note that all our patients without palliative procedures did not show abnormalities in lung perfusion. Major abnormalities of lung perfusion seemed related to possible intimal thrombosis or emboli due to prolonged polycythemia or to pulmonary vessel distortion due to long-standing shunts.

Hemodynamic responses to isolated increments in heart rate by atrial pacing after a Fontan procedure

The physiologic role of the right ventricle has long been a subject of interest to physiologists. The Fontan operation provides a human model for studying the circulation in series devoid of a subpulmonic right ventricle. The hemodynamic response to isotonic exercise in this setting has been established, and differs appreciably from normal. However, the physiologic response to an increase in heart rate (atrial pacing) as an isolated variable has not been examined and compared to atrial pacing in hearts with two concordant subarterial ventricles. Accordingly, we compared the supine bicycle exercise response to rate-equivalent right atrial pacing in nine patients after atriopulmonary anastomoses (the Fontan operation) for single ventricle or tricuspid atresia. Cardiac index increased 77% with exercise (rest 2.6 L/min/m2; exercise 4.6 L/min/m2) but decreased 12% with atrial pacing (rest 2.5 L/min/m2; pacing 2.2 L/min/m2). Pulmonary arterial oxygen saturation declined significantly during exercise (rest 68%; exercise 31%) and during atrial pacing (control 72%; pacing 64%). The mean increment in pulmonary arterial pressure was 1.3 times greater with exercise (rest 14 mm Hg; exercise 20 mm Hg) than with pacing (control 12 mm Hg; pacing 16 mm Hg). Peak systemic arterial systolic pressure increased 14% with exercise but was unchanged by pacing. Systemic and pulmonary vascular resistances fell with exercise but changed insignificantly during atrial pacing. Stroke volume rose slightly with exercise but fell significantly with pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Embolectomy for acute pulmonary artery occlusion following Fontan procedure

A 5-year-old child experienced acute hemodynamic decompensation and hypoxia four weeks following an uneventful Fontan procedure for univentricular heart. Cardiac catheterization revealed complete occlusion of the left pulmonary artery, and emergent pulmonary artery embolectomy was performed. The source of the embolus was the atrial septal patch. Because of the altered hemodynamics following the Fontan procedure, stasis of right atrial blood and thrombus formation may occur. Routine anticoagulation immediately following operation is recommended. Prompt diagnosis and treatment with embolectomy may be lifesaving.

Left ventricular characteristics during exercise in patients after Fontan's operation for tricuspid atresia

Left ventricular function during supine bicycle exercise was studied using multigated blood pool imaging in ten patients with tricuspid atresia after Fontan's operation and in 13 children and adults (control group). The mean age of the patients was 16 years and the mean interval between operation and study was 5 years. The peak work loads that the patients could perform were similar to those in the control group. Work loads and heart rates during radionuclide study in the operated group were also similar to those in the control group. The left ventricular ejection fraction at rest and during exercise in the operated group was less than in the control group, although the net increase during exercise was similar in the two groups. During exercise, left ventricular end-diastolic volume decreased significantly in the operated group. In the control group, this variable did not change significantly. Left ventricular stroke volume increased during exercise in the control group but it did not change significantly in the operated group. These data indicate that in patients after Fontan's operation, left ventricular performance remains low during exercise, which is in part due to diminished left ventricular preload reserve, and this in turn may be caused by reduced reserve of right heart output.

Dysrhythmias after the modified Fontan procedure

The cardiac rhythm before and after the modified Fontan procedure was reviewed in 24 patients. Transient atrial dysrhythmias were common in the immediate postoperative period. Late postoperative premature atrial contractions were detected by ambulatory monitoring in 20 of 23 patients; eight (34.8%) had supraventricular tachycardia. Late ventricular dysrhythmia was detected in 18 of 23 patients: ten had low-grade ventricular dysrhythmias and eight (34.8%) had multiform premature ventricular contractions. Five of the latter had couplets and one of these five plus another had ventricular tachycardia. Seven patients with supraventricular tachycardia and five patients with ventricular dysrhythmia required antiarrhythmic medication. Asymptomatic bradycardia was detected in five patients (21.7%). One patient had intermittent second-degree atrioventricular block. No specific risk factors predicted dysrhythmias. Thus, cardiac dysrhythmias were common in patients after the modified Fontan procedure, but were well tolerated in most patients. No sudden deaths or syncopal episodes have occurred during a mean follow-up of 5 years. One patient's death was related to severe left ventricular dysfunction. Permanent pacing has not been required in any patient.

Left ventricular function in tricuspid atresia: a radionuclide study

Left ventricular function was evaluated by radionuclide angiocardiography in patients with tricuspid atresia before and after the Fontan operation. Ejection fraction was 0.54 +/- 0.13 in 29 patients without the Fontan procedure and 0.56 +/- 0.14 in 14 postoperative patients. Group means were not statistically different, but both were less than normal values for the institution (p less than 0.001). Function did not correlate significantly with age or aortic oxygen saturation. Serial studies demonstrated little change in eight of nine patients examined over 1 to 3 years preoperatively. From the preoperative group of nine patients with abnormal ejection fraction, three underwent surgery, with two survivors. Although 5 of 14 patients had abnormal systolic function after the Fontan operation, only 1 was symptomatic. Depressed response to isometric exercise was found in two patients with a normal ejection fraction at rest. Group systolic function after Fontan surgery did not correlate significantly with age at surgery but all patients were operated on at more than 5 years of age. Of seven patients studied both preoperatively and postoperatively two had an increase and three a decrease in ejection fraction. The trend in these seven studied serially after surgery was toward early improvement in ejection fraction. This study shows variability in left ventricular performance in patients with tricuspid atresia before and after surgery. Individuals undergoing the Fontan procedure after 5 years of age do not necessarily have an increase in ejection fraction over preoperative values, and may even have a decrease. Serial improvement over early postoperative results may be expected, without significant deterioration, during the next 1 to 3 years.

Exercise tolerance and cardiorespiratory response to exercise after the Fontan operation for tricuspid atresia or functional single ventricle

To determine the impact of the Fontan operation on exercise tolerance and on the cardiorespiratory response to exercise, we compared the results of graded exercise to maximal effort of 81 patients with tricuspid atresia or single functional ventricle studied preoperatively with those of 29 patients studied postoperatively. Postoperatively, the values for total work performed, duration of exercise and maximal oxygen uptake increased significantly. Regardless of operative status, the maximal heart rate during exercise was reduced. The cardiac output and stroke volume response to exercise were subnormal after operation. Systemic arterial blood oxygen saturation was reduced markedly preoperatively both at rest and during exercise; postoperatively, it was significantly greater than the preoperative value but it remained slightly abnormal. The ventilatory response to exercise (respiratory rate, minute ventilation and ventilatory equivalent for oxygen) decreased toward normal after operation. Exercise tolerance and the cardiorespiratory responses to exercise improve after the Fontan operation. Formal exercise testing is essential to quantitate the degree of improvement.

Response to the Valsalva maneuver after the Fontan procedure for tricuspid valve atresia, single ventricle or pulmonic valve atresia

The Valsalva maneuver was performed during cardiac catheterization in 9 patients who had undergone a Fontan operation (Fontan group) and in 10 control subjects. The Fontan group had higher right atrial (RA) pressure (16 +/- 1 vs 4 +/- 0.5 mm Hg, p less than 0.001), lower cardiac index (2.5 +/- 0.1 vs 3.7 +/- 0.2 liters/min/m2, p less than 0.05), lower stroke index (32 +/- 2 vs 44 +/- 2 ml/beat/m2, p less than 0.05), and higher systemic vascular resistance (31 +/- 1 vs 24 +/- 1 units, p less than 0.05) than the control group. Four patients in the Fontan group had a normal 4-phase Valsalva response, and 5 did not (p less than 0.05). RA pressure was similar in those who responded normally and those who did not (16 +/- 0.5 vs 17 +/- 1 mm Hg), whereas in those who responded normally cardiac index was higher (2.9 +/- 0.2 vs 2.2 +/- 0.1 liters/min/m2, p less than 0.05), stroke index was higher (36 +/- 1 vs 28 +/- 1 ml/beat/m2, p less than 0.05), and systemic vascular resistance was lower (28 +/- 1 vs 31 +/- 1, p less than 0.05). It is concluded that cardiac output is a better predictor of a normal response to the Valsalva maneuver than RA pressure in patients after the Fontan procedure. A normal response to the supine Valsalva maneuver suggests a cardiac index greater than 2.4 liters/min/m2 and stroke index greater than 31 ml/beat/m2.

Results of the modified Fontan operation for congenital heart lesions in patients without preoperative sinus rhythm

Preoperative sinus rhythm has been a criterion for the Fontan operation. However, of 297 patients who underwent the Fontan operation between October 1973 and February 1984, 12 (4%) did not have sinus rhythm. The age at operation ranged from 4 to 34 years (median 15). Nine patients had a univentricular heart, two had tricuspid atresia and one had a complex form of transposition. In all 12 patients, 3 to 8 of the 10 proposed criteria for operability were not met. An atrioventricular (AV) conduction abnormality was present in seven patients, six with complete AV block and one with AV dissociation. The patient with complex transposition had complete AV block and atrial fibrillation. Postoperatively, all seven patients continued to have an AV conduction abnormality, and those with complete AV block had a permanent pacemaker implanted. Six of the 12 study patients had atrial flutter or fibrillation refractory to antiarrhythmic medications. Postoperatively, four of the six patients had sinus rhythm. Two of the six patients had complete AV block (including the patient with complex transposition) and both had a permanent pacemaker implanted. Three of the 12 patients died (mortality rate 25%). The nine survivors were followed up for 6 to 55 months; no late deaths occurred. All had marked clinical improvement. This study demonstrates that 1) complete AV block is not a contraindication to the Fontan operation, 2) some patients may not require AV synchrony postoperatively for survival, and 3) postoperative atrial flutter or fibrillation may cease or be easier to control after the Fontan operation.

Radionuclide assessment of ventricular contraction at rest and during exercise following the Fontan procedure for either tricuspid atresia or single ventricle

Ventricular contraction was evaluated in 18 patients studied at a mean of 2.6 years after Fontan repair. The diagnosis was tricuspid atresia in 9 patients and single ventricle in 9. Gated first-pass and gated equilibrium radionuclide ventriculography were performed at rest and during exercise. Abnormally low ventricular ejection fraction (EF) at rest was present in 8 of 18 patients by the gated equilibrium technique and 6 of 13 technically adequate gated first-pass studies. An abnormal response to exercise (failure of EF to increase less than or equal to 5% from rest to maximal exercise) was found in 10 of 16 patients by the gated equilibrium technique and in 8 of 12 by the gated first-pass technique. Only 2 patients by each radionuclide technique had both normal EF at rest and normal exercise response. Thus, this study confirms the frequent presence of abnormalities in ventricular contraction after the Fontan procedure at rest or during exercise or both despite absence of symptoms. Both EF response and the hemodynamic response during exercise were more abnormal in the presence of an atriopulmonary than an atrioventricular connection.

Surgical treatment of tricuspid atresia

Despite increasing experience with the surgical treatment of tricuspid atresia, controversy exists regarding the early and late results of the various surgical options. Between January 1, 1967, and September 1, 1982, 92 patients underwent 147 operations for tricuspid atresia. Eighty-five patients underwent 1 or more palliative operations (108 procedures), with 8 hospital deaths (9%; confidence limits [CL], 6 to 14%). Thirty-eight patients underwent 44 classic (Blalock-Taussig or Gore-Tex) shunts, with 3 early (7%; CL, 3 to 13%) and 3 late deaths. Actuarial survival at 5 years was 78%, but only 56% were alive and free from having to undergo further operation at 5 years. Thirty-seven patients underwent a Fontan procedure, with 5 hospital deaths (14%; CL, 8 to 22%). Of these 37 patients, 34 (92%) had a nonvalved connection between the right atrium and the right ventricular infundibulum or the pulmonary artery. Incremental risk factors for hospital mortality after the Fontan procedure in patients with tricuspid atresia as well as other cardiac anomalies include young age (p = 0.0003), diagnosis other than tricuspid atresia (p = 0.03), and complex associated procedures (p = 0.02). During the year 1983, hospital mortality was 7% (1 out of 14; CL, 1 to 22%) for the Fontan procedure without complex additional procedures. Actuarial survival after a Fontan procedure was 71% at 5 years, with 3 patients requiring late reoperation. Of the survivors, 96% are in New York Heart Association Functional Class I or II. The Fontan procedure without a valve offers good intermediate survival, good functional results, and few reoperations. In patients with diminished pulmonary blood flow, a classic shunt also provides good palliation and good intermediate survival, but there is a necessity for additional operations in many patients within 5 years.

Systemic venous and pulmonary arterial flow patterns after Fontan's procedure for tricuspid atresia or single ventricle

Despite increasing use of Fontan or modified Fontan repairs, the comparative hemodynamic efficacy of different types of connections are unresolved. Accordingly, we undertook a prospective study designed to determine postoperative flow patterns after Fontan's operation. Seven subjects had tricuspid atresia and eight had single ventricle. Ages ranged from 5 to 38 years (mean 16.4). Ten subjects had nonvalved right atrial-to-pulmonary arterial connection, and four had nonvalved right atrial-to-right ventricular communication. A valved conduit established continuity between the right atrium and right ventricle in one subject. Doppler flow profiles were recorded in the pulmonary artery and in the superior and inferior venae cavae of each. A reference electrocardiogram was used for timing purposes. In 14 patients, forward flow in the pulmonary artery was biphasic. Flow began at the end of the T wave (early ventricular diastole), peaked at or before the P wave (atrial systole), and returned to baseline by the peak of the R wave. Forward flow recommenced at the peak of the R wave (ventricular systole) and returned to baseline at the end of the T wave. Flow in the superior vena cava varied, and could not be recorded in three subjects. Between the end of the P wave and peak of the R wave (atrial systole) flow was reversed in eight, absent in three, and forward in one patient. Forward flow occurred between the peak of the R wave and the end of the T wave and was either continuous or biphasic. Fourteen patients had adequate studies of inferior vena cava flow; reversed flow during atrial systole occurred in 10 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Histopathological evaluation of woven and knitted Dacron grafts for right ventricular conduits: a comparative experimental study

Composite extracardiac conduits consisting of a low-porosity woven graft and a high-porosity knitted double-velour Dacron graft presealed with fibrin glue were implanted between the right ventricle and the pulmonary artery in 6 dogs under partial heparinization. Two grafts were explanted after 6 weeks, 2 after 12 weeks, and 2 after 6 months. The healing properties of both types of prosthesis were studied macroscopically, under light microscopy, and with scatter electron microscopy. Spontaneous peeling of both the inner and outer capsules of the graft occurred in 3 of 6 woven prostheses during transection. In the remaining 3, peeling could be easily induced by blunt dissection; this was impossible in the knitted grafts. Microscopically, in a comparison of the different weaves after identical time intervals, the inner capsule was noticeably thicker in woven than in knitted grafts. Transtitial ingrowth of fibroblastic tissue could be observed in knitted grafts after 6 weeks; only poor transmural tissue bridging was detectable in woven prostheses after 6 months. Neovascularization of the inner capsule was detectable earlier and was more advanced toward the luminal surface of highly porous grafts. In conclusion, knitted grafts in the position of extracardiac right ventricular conduits showed firmer attachment of both inner and outer capsules to the prosthetic material. Also, the inner capsule remained thinner and revealed a higher degree of neovascularization than in the woven Dacron grafts.

Dynamics of right heart flow in patients after Fontan procedure

In seven patients who underwent Fontan procedures but in whom no valves were inserted, dynamics of right heart flow were evaluated with the use of a catheter-tipped velocity transducer, pulsed Doppler echocardiography, and angiocardiography. Right atrial (RA) contraction caused a forward flow to the pulmonary artery (PA) and a backward flow to the inferior vena cava (IVC). Backward flow to the superior vena cava (SVC) was minimal. As the right atrium relaxed, a rapid forward flow occurred at the IVC and SVC that filled the atrium and a small amount of pulmonary regurgitant flow was observed. Subsequently, a forward flow was observed at the IVC, SVC, and PA during RA diastole. Angiographically determined RA stroke volume (SV) was less than 40% of the left ventricular (LV) SV in three patients in whom the postoperative increase in atrial "a" wave pressure (delta p) was greater than 8 mm Hg, while it was similar to or greater than LVSV in four patients in whom delta p was 6 mm Hg or less. In all patients LV end-diastolic volume was 107 +/- 27(SD)% of normal but LV ejection fraction was 0.53 +/- 0.07, resulting in the reduced cardiac output (2.8 +/- 0.7 l/min/m2). There was no correlation between the RASV or RA ejection fraction and cardiac output. These data show that the RA contraction causes a forward flow to the PA and that pulmonary regurgitation is not significant after Fontan procedure even when valves are not inserted. Also, the postoperative increase in the RA afterload may depress RA function.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular performance in adults after operation for congenital heart disease

Symptomatic ventricular dysfunction in adults who have had reparative operations for the more common congenital heart defects is uncommon. However, both invasive and noninvasive laboratory assessments of ventricular function have revealed abnormalities in some subsets of patients after repair of atrial septal defect, ventricular septal defect, aortic or pulmonary stenosis, tetralogy of Fallot, transposition of the great arteries and tricuspid atresia. Possible causative factors of late ventricular dysfunction after repair include the duration and severity of volume or pressure overload; the duration and severity of cyanosis; intermittent episodes of imbalance between myocardial oxygen supply and demand; residuae, sequelae and complications of treatment; and acquired disease. Further long-term follow-up studies are needed to assess the effect of current methods of therapy as well as timing of operative intervention on ventricular function in adults.