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J Thorac Cardiovasc Surg 1995;110:180-185
© 1995 Mosby, Inc.
SURGERY FOR CONGENITAL HEART DISEASE |
Tenri, Nara, Japan
Received for publication May 26, 1994. Accepted for publication Nov. 28, 1994. Address for reprints: Yutaka Okita, MD, Department of Cardiovascular Surgery, National Cardiovascular Center, Fujishirodai 5-7-1, Suita, Osaka, Japan 565.
Abstract
Between November 1966 and December 1990, 511 pediatric patients with tetralogy of Fallot underwent corrective operation at Tenri Hospital. There were 78 patients with subarterial ventricular septal defect. Mean age at repair was 5.6±3.3 years. The method of right ventricular outflow tract reconstruction was simple infundibulectomy in 14 patients, right ventricular outflow patch in 36, and transannular patch in 28. There were 7 (9.0%) early deaths as a result of low cardiac output syndrome and acute renal failure. The pressure ratio of the right ventricle to the left ventricle was 0.62±0.18 during the early postoperative catheterization. Follow-up was achieved for 442.6 patient-years and ranged from 0.5 to 27 years, with an average of 8.5±6.7 years. There were three late deaths (2 cardiac and 1 noncardiac). Actuarial survival was 94.8%±4.0% at 20 years. Catheterization during late follow-up (6.8±4.7 years after repair) was done in 53 patients and the pressure ratio of the right ventricle to the left ventricle was 0.48±0.21. Fifteen patients underwent subsequent operation because of residual lesions, including ventricular septal defect in four patients, pulmonary stenosis in nine, combined ventricular septal defect and pulmonary stenosis in one, and pulmonary regurgitation in one, with no mortality. Actuarial rate of freedom from reoperation was 71.1%±8.0% at 10 years and 58.8%±16.8% at 20 years. Patients with tetralogy and subarterial ventricular septal defect were more likely to have the development of residual obstruction at the level of the pulmonary valve anulus after repair than were those with tetralogy and perimembranous ventricular septal defect. (J THORACCARDIOVASCSURG1995;110:180-5)
Tetralogy of Fallot with doubly committed subarterial ventricular septal defect (VSD) is relatively more common among Orientals than among whites and has special features of surgical importance.
1 Despite the benign natural course, mild cyanosis, and large pulmonary arteries, a considerable prevalence of residual pulmonary stenosis after repair of this anomaly has been reported. 2, 3 This report describes 28 years of experience in the surgical management of tetralogy of Fallot with subarterial VSD at Tenri Hospital in Japan.
PATIENTS AND METHODS
Between November 1966 and December 1990, 547 patients with tetralogy of Fallot underwent corrective operation at Tenri Hospital. With the exclusion of patients older than 16 years and of those with VSD and pulmonary atresia, 511 patients remained. The study population included 78 patients with subarterial VSD, including 41 patients with a VSD that extended from the pulmonary anulus to the membranous septum, the so-called total conal defect. The control group included 433 patients with tetralogy and perimembranous VSD who underwent repair during the same period (Table I). Before operation, patients with subarterial VSD had less frequent anoxic spells, better arterial oxygen saturation, greater pulmonary blood flow, and well-developed pulmonary arterial trees compared with respective findings in patients with perimembranous VSD.
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4 was not fulfilled. In the subarterial VSD group, there was a greater prevalence of the use of a transannular patch to increase the size of the outflow tract of the right ventricle (RV) to the main pulmonary artery (Table II). Postoperative catheterization was done 1 to 2 months after repair in 241 patients in whom residual lesions were suspected and in 318 patients 6.8 ± 3.8 years after operation. Residual pulmonary stenosis (PS) was defined as a pressure gradient between the RV and the right pulmonary artery of more than 50 mm Hg or a pressure ratio of the RV to the left ventricle of more than 0.70. Severity of pulmonary regurgitation and aneurysm of the right ventricular outflow tract (RVOT) was graded in four degrees ranging from none to severe.
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RESULTS
There was no significant difference detected regarding early postoperative mortality in 7 patients (9.0%) in the subarterial VSD group and 52 patients (12.1%) in the perimembranous VSD group. The cause of death in the subarterial VSD group was low cardiac output syndrome in five patients and acute renal failure in two. Early postoperative catheterization showed a significantly higher prevalence of residual VSD and PS in the subarterial VSD group (Table III).
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Table IV). Actuarial survival was 94.8% ± 4.0% at 20 years in the subarterial VSD group, which was comparable to 91.6% at 20 years in the perimembranous VSD group (Fig. 1).
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Table V). The prevalence of reoperation was higher in the subarterial VSD group. On actuarial study, the incidence of subsequent operation was significantly lower at 10, 15, and 20 years in the subarterial VSD group than that in the perimembranous VSD group (Fig. 2).
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Table VI). On analysis of the variables against late PS, only subarterial VSD was a significant predictor of greater P(RV/LV) and residual gradient in the outflow tract (Tables VII and VIII).
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Similar to the simple type of doubly committed subarterial VSD, tetralogy of Fallot with doubly committed subarterial VSD is much more common in Oriental than Occidental countries. Although these cases account for approximately 10% to 30% of all tetralogy cases in Japan, 1, 5 in the United States and western Europe the incidence of tetralogy with doubly committed subarterial VSD is only 6% to 8%. 2, 3, 6 In strict morphologic terms, these cases should not be classified as tetralogy because they lack the anteriorly deviated infundibular septum of tetralogy that produces the malalignment VSD with aortic overriding and PS. 7
In most cases, the pulmonary arteries are of adequate size, usually with a sound pulmonary valve anulus, and patients show less severe cyanosis than patients with tetralogy combined with perimembranous VSD. 8, 9 This is presumed to be related to the absence or deficiency of part of the anteriorly displaced infundibular septum, which prevents development of a fixed obstruction in the RVOT. The severity of the RV obstruction depends on the severity of pulmonary valvular stenosis, the development of the septal or anterior muscle of the RVOT, or hypoplasia of the pulmonary arterial tree. Despite the benign natural course and less severe anatomy, the prevalence of unrelieved PS and resultant poor outcome is quite high if the RVOT is not properly enlarged. 1, 2
The VSD patch extends up to the RVOT and causes a narrowing beneath the pulmonic ring, for which patch enlargement is required in the majority of cases. The patch does not always need to extend across the pulmonary anulus. There is further risk of surgical damage to the aortic valve that may produce aortic regurgitation during ventriculotomy and during closure of the VSD.
Neirotti and associates 2 stressed that the closure of the subarterial VSD increased the apparent severity of PS and necessitated a transannular patch in patients whose RVOT before repair did not appear to need such patching. de Leval and associates 3 reported that 10 (76%) of 13 patients with tetralogy and subarterial VSD needed transannular patch enlargement. However, Vargas and associates 10 reported that patients with tetralogy with subarterial VSD had a nonrestrictive pulmonary ring more often than previously thought and that the prevalence of transannular patching had decreased to 20% in their recent series. The prevalence of transannular patching in our series was 36% and the prevalence of resultant PR and bulging RV was higher than that in patients with perimembranous VSD. Although a high postrepair P(RV/LV) ratio is a well-known determinant for early and late death in tetralogy, 11, 12 severe PR caused by an excessively large transannular patch is likely to cause RV dysfunction after repair. 13, 14
Presently, our standard minimal requirement for pulmonary annular size, measured by direct Hegar's dilator immediately after right ventriculotomy or pulmonary arteriotomy, to preserve the pulmonary annular ring is a Z value 4 of -3 for tetralogy with perimembranous VSD 11 or a Z value of 0 for tetralogy with subarterial VSD. Liberal use of outflow patch, transannular if necessary, and extensive infundibulectomy were essential to relieve PS in this anomaly.
However, postoperative conduction disturbance in patients with tetralogy and subarterial VSD was less frequent in our series. Thirty-seven (47.4%) patients had subarterial VSD, which did not extend to the membranous portion of the interventricular septum. The fusion of the posterior limb of the trabecula septomarginalis with the ventriculoinfundibular fold produced a protective muscular bundle for the conduction systems at the posteroinferior angle of the VSD. 7
Conclusion
Seventy-eight pediatric patients who had tetralogy of Fallot with subarterial VSD underwent corrective operation. There were 7 (9.0%) early deaths and three late deaths. Although the late survival was satisfactory, actuarial study revealed that 71% of patients remained free from subsequent operation necessitated by residual PS and VSD at 10 years and this rate dropped to 59% at 20 years. More radical management in the relief of RV obstruction in this group of patients is justified.
Footnotes
From the Departments of Cardiovascular Surgerya and Pediatric Cardiology,b Tenri Hospital, Tenri, Nara, Japan. 
*Present address: Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan.
References
This article has been cited by other articles:
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  T. Ishizaka, H. Ichikawa, Y. Sawa, N. Fukushima, K. Kagisaki, H. Kondo, S. Kogaki, and H. Matsuda Prevalence and optimal management strategy for aortic regurgitation in tetralogy of Fallot Eur. J. Cardiothorac. Surg., December 1, 2004; 26(6): 1080 - 1086. [Abstract] [Full Text] [PDF]
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Q. Wu Indication and Technique of Total Correction of Tetralogy of Fallot in 228 Patients Ann. Thorac. Surg., June 1, 1996; 61(6): 1769 - 1774. [Abstract] [Full Text]
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