Asian Cardiovasc Thorac Ann 2002;10:356-358
© 2002 Asia Publishing EXchange Pte Ltd
Adult Presentation of Complete Atrioventricular Septal Defect
Murray H Kown, MD,
Luca Vricella, MD,
Christopher T Salerno, MD,
David N Rosenthal, MD1,,
Michael D Black, MD
Department of Cardiothoracic Surgery
1 Department of Pediatrics Stanford University School of Medicine Stanford, California, USA
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For reprint information contact: Michael D Black, MD Tel: 1 650 725 6407 Fax: 1 650 725 3846 email: michael.black{at}leland.stanford.edu Department of Cardiothoracic Surgery, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA.
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ABSTRACT
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Complete atrioventricular septal defect generally presents early in life with symptoms of congestive heart failure. Untreated, patients almost universally develop irreversible pulmonary hypertension. We present an unusual case of a Down’s syndrome patient whose septal defect first presented at 20 years of age.
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INTRODUCTION
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Atrioventricular septal defect (AVSD) results from a congenital abnormality in the fusion of the endocardial cushions, leading to left-to-right shunts. Children with the complete form of this disorder (CAVSD) generally present early in life with symptoms of congestive heart failure and ultimately develop irreversible pulmonary hypertension in the absence of corrective treatment. Historically, treatment included pulmonary artery banding, although definitive early repair is preferred now and is achieved with low mortality and good long-term results.1 We describe an unusual first presentation of CAVSD in an adult.
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CASE REPORT
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The patient was a 20-year-old male who recently immigrated from Mexico. He was diagnosed with trisomy 21 and congenital heart disease at birth, but had had little follow-up until his recent presentation in the United States. Other than mild fatigue with exertion, he had no other cardiac symptoms and was not taking medication. He did have long-standing sleep apnea, most likely due to the macroglossia characteristic in trisomy 21 patients. He had a plethoric (ruddy) complexion and evidence of digital clubbing. There was a single second heart sound with increased intensity and an accentuated precordial impulse. The echocardiogram showed a CAVSD and a left-to-right shunt (Figure 1A
). Cardiac catheterization confirmed a Qp : Qs shunt fraction of 3.3 with systemic pulmonary arterial pressure of 115/50 mm Hg (mean, 77 mm Hg). Pulmonary vascular resistance was elevated to 7.3 mm Hg.L-1.min-1. Interestingly, his pulmonary vasculature was reactive to both 20 ppm nitric oxide (4.2 mm Hg.L-1.min-1) and 100% oxygen administration (0.9 mm Hg.L-1.min-1). Systemic oxygen saturation at room air was low-normal at 93% and was presumably related to sleep apnea and intermittent bidirectional shunting. The patient was normocarbic (carbon dioxide tension, 40 mm Hg).
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Figure 1. (A) Preoperative echocardiogram showing the common atrioventricular valve (arrows). (B) Postoperative echocardiogram showing obliteration of the shunts at both the atrial and ventricular levels with the creation of 2 independent atrioventricular valves within the common atrioventricular valve annulus (arrows). LA = left atrium, LV = left ventricle, RA = right atrium, RV = right ventricle.
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At the time of surgical repair, a large ostium primum defect was identified in addition to a large ventricular septal defect with a common atrioventricular valve. After single-patch repair of the defect with mitral valve cleft closure, intraoperative echocardiography revealed no residual shunt and only mild atrioventricular valve regurgitation (Figure 1B
). A temporary pulmonary artery line was inserted. It was removed after it showed pulmonary arterial pressure one-third of systemic levels.
The postoperative course was complicated by the development of supraventricular tachycardia shortly after oxygen administration by nasal cannula was discontinued. This spontaneously converted to a sinus rhythm after oxygen was readministered. Since discharged from hospital with 0.5 L.min-1 oxygen supply, the patient had done well, ultimately weaning to room air breathing and having increased energy levels.
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DISCUSSION
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The natural course of children with untreated CAVSD is generally progressive unrelenting pulmonary vascular disease.2 The disorder is usually readily detected, however, by echocardiography in infants presenting with symptoms of cyanosis.3 This has facilitated early surgical correction before the development of irreversible pulmonary hypertension and congestive heart failure.
Because of the severity of symptoms in CAVSD and the relative sensitivity and specificity of current imaging tools, diagnosis during adulthood is extremely rare.4 Late presentation in patients with trisomy 21 is also unusual as the development of elevated pulmonary vascular resistance is more severe and rapid in these patients.5,6 One of the factors that allowed this patient to progress relatively symptom-free into adulthood may have been the protective vasoconstrictive effect of hypoxia secondary to sleep apnea. Hypoxic vasoconstriction is a defining characteristic of the pulmonary circulation, and a study has indeed found vasoconstriction in the pulmonary vasculature during obstructive sleep apnea.7 This "auto-pulmonary artery banding" phenomenon from enduring hypoxia may have protected this patient’s pulmonary bed from the development of irreversible disease. His preoperative responsiveness to both administered nitric oxide and oxygen is indicative of this preservation.
The patient’s reactivity to oxygen persisted into the postoperative period, with the onset of supraventricular tachycardia coinciding with the discontinuation of oxygen supply. The consequent fall in oxygen saturation led to an increase in right-sided heart pressure and atrial dilatation, due to increased pulmonary vascular resistance as well as the loss of ability to shunt blood across a previously patent ventricular septal defect. This corrected spontaneously with supplemental oxygen, and the patient remained in sinus rhythm following discharge. Similar reactivity in the pulmonary vasculature of Down’s syndrome patients has been reported where the higher pulmonary to systemic vascular resistance seen in these children almost completely disappeared after 100% oxygen administration.8
The true incidence of undiagnosed CAVSD in the adult population may be underestimated, particularly in regions where medical care is limited. Increasing migration today may bring forth larger numbers of such patients, perhaps compelling us to redefine one day what is considered normal disease presentation of this complex congenital disorder.
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REFERENCES
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ABSTRACT
INTRODUCTION
