Asian Cardiovasc Thorac Ann 2008;16:e52-e54
© 2008 Asia Publishing EXchange Ltd
Operative Timing for Absent Pulmonary Valve with Obstructive Sleep Apnea
Yoshitaka Hayashi, PhD,
Garry J Barron, FRACP1,
Aubrey A Almeida, FRACS
Department of Surgery (Cardiothoracic Surgery Unit)
1 Department of Cardiology Monash Medical Center, Monash University Clayton, Australia
For reprint information contact: Yoshitaka Hayashi, PhD Tel: 81 6 6774 5111 Fax: 81 6 6774 5131, Email: yoshimmc{at}river.ocn.ne.jp, Division of Cardiovascular Surgery, Osaka Red Cross Hospital, 5-30 Fudegasaki-cho, Tennoji-ku, Osaka City, Osaka 543-8555, Japan.
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ABSTRACT
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Congenital absence of the pulmonary valve appears to have a prolonged fate, despite substantial regurgitation, thus the optimal timing of surgical correction remains unclear. A 53-year-old man with isolated pulmonary regurgitation accompanied by obstructive sleep apnea developed progressive heart failure after reopening of the foramen ovale. Closure of the interatrial shunt and pulmonary valve replacement with a 25-mm mechanical prosthesis relieved his refractory left heart failure.
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INTRODUCTION
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Congenital absence of the pulmonary valve is a rare entity of unknown etiology, characterized by dysplastic or hypoplastic pulmonary valve leaflet tissue, and usually associated with tetralogy of Fallot; isolated congenital absence of the pulmonary valve is uncommon.1,2 Isolated pulmonary regurgitation appears to be well tolerated over a long period, despite substantial regurgitant blood flow.2–4 In neonates, this anomaly usually causes severe respiratory distress due to tracheobronchial compression by the dilated pulmonary arteries. Most adults are asymptomatic and present with exercise intolerance later in life.1–4 Right ventricular (RV) dilatation, which reflects the severity and duration of ventricular insufficiency, is usually observed in patients with isolated pulmonary regurgitation. However, severe heart failure due to RV overload is a rare symptom in those without coexisting cardiac or pulmonary factors.1,2 The optimal timing of surgery for isolated pulmonary regurgitation remains unclear because of these clinical characteristics.
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CASE REPORT
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A 48-year-old man with exertional dyspnea was diagnosed with cardiomyopathy and moderate pulmonary regurgitation. He had undergone ventricular septal defect repair at 8 years old, and then led a normal life with no history of rheumatic fever or fever of unknown origin. He was critically obese (body weight, 96 kg; body mass index, 33.6 kg·m–2) and suffered from obstructive sleep apnea with normal respiratory function. Medical treatment including a beta blocker controlled his symptoms in New York Heart Association class II.
At 52 years old, he was transferred to our hospital for evaluation of progressive exertional dyspnea, fatigability, and left upper chest pain, despite medical therapy. Chest radiography demonstrated severe cardiomegaly with a prominent pulmonary arterial segment. Electrocardiography showed normal sinus rhythm with complete right bundle branch block and right axis deviation (+91 degrees). An echocardiogram revealed gross RV enlargement and left ventricular (LV) compression with paradoxical septal motion. Right ventricular and LV diastolic dimensions, which had been respectively 30 and 68 mm at the age of 49 years, were now 45 and 51 mm, respectively. Doppler studies indicated severe pulmonary regurgitation with a to-and-fro pattern, and moderate tricuspid regurgitation. A mitral inflow relaxation abnormality with shortened E deceleration time was noted, as well as a significant left-to-right shunt through a secundum atrial septal defect (ASD) that had not been detected in previous echocardiography. There were no findings related to tetralogy of Fallot. Cardiac catheterization demonstrated pulmonary arterial pressure of 43/12 mm Hg, RV pressure of 41/9 mm Hg, and LV pressure of 125/18 mm Hg, with a characteristic dip-and-plateau configuration. The calculated pulmonary-to-systemic flow ratio was 1.5. Coronary angiography showed no significant coronary artery disease. Left ventriculography revealed a normal ejection fraction, but the LV wall was severely compressed by the dilated right ventricle. Despite maximal medication, the patient continued to have dyspnea and fatigue on mild exertion. He also suffered an episode of epilepsy and had erectile dysfunction due to left heart failure. It was decided that pulmonary valve replacement and ASD closure should be carried out to avoid RV failure and subsequent LV constrictive-restrictive physiology.
Inspection of the heart showed dilated right atrium and ventricle, including the pulmonary artery. Left ventricular wall motion was generally mildly hypokinetic, and restrictive-constrictive due to compression by the dilated right ventricle. The pulmonary valve was tricuspid and all leaflets were hypoplastic without calcification. There were no pathologic signs of active or previous infectious endocarditis. Pulmonary valve replacement was performed with a 25-mm aortic mechanical prosthesis (ATS Medical, Inc., Minneapolis, MN, USA), based on the patient’s preference. The 20 x 10-mm inferoposterior ASD proved to be the reopened foramen ovale; it was closed directly with 4/0 Prolene suture in 2 layers. The tricuspid valve was morphologically normal. The operation was completed without any complications. The postoperative course was uneventful, and the patient was discharged on the 5th postoperative day. His symptoms improved gradually after the operation, and erectile dysfunction was eventually relieved. Histological findings showed marked accumulation of myxoid ground substance, patchy stromal hyalinization, elastotic degeneration, and deposition of fibrin in the excised valve cusps.
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DISCUSSION
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This patient had undergone ventricular septal defect repair in childhood and had led a normal life with no other congenital anomalies, so this case was considered to be isolated pulmonary regurgitation. The pathophysiological features of isolated pulmonary regurgitation are right heart failure in adulthood, and most patients are asymptomatic for many decades.1–4 Ansari1 reported that 40% of patients were symptomatic with progressive exertional dyspnea, fatigability, and left upper chest pain, indicating left heart failure. In previous reports, patients presented with symptoms related to left heart failure, and echocardiography revealed a small left ventricle compressed by a dilated right ventricle.3,4 These hemodynamic and echocardiographic characteristics were observed in our patient in a deteriorated condition, and LV diastolic dysfunction mediated by RV enlargement can be considered a crucial factor in refractory heart failure in those with isolated pulmonary regurgitation. Tanabe and colleagues3 described a case where RV function remained depressed 1 month after surgery performed in a decompensated condition. It is important not to miss any signs suggesting restrictive-constrictive physiology of the left ventricle, and serial assessment of RV performance by echocardiography is needed to establish the appropriate timing of pulmonary valve replacement.
Obstructive sleep apnea is characterized by repeated partial or complete closure of the pharynx, gasping episodes, sleep fragmentation, and daytime sleepiness. Recently, it has been recognized as an independent risk factor for several adverse effects on the heart and cardiovascular system.5 The pathophysiological effects of obstructive sleep apnea on the cardiovascular system involve complex mechanical, hemodynamic, neurohumoral, and inflammatory mechanisms.5 Futile inspiratory efforts against the occluded pharynx cause an abrupt reduction in intrathoracic pressure, with enhanced venous return, RV distension, and a leftward shift of the interventricular septum. These geometric changes are thought to reduce LV filling.5,6 In view of these features, obstructive sleep apnea may play a pivotal role in exacerbating LV diastolic dysfunction. Shivalkar and colleagues7 demonstrated that LV and RV structural and functional changes occur in patients with obstructive sleep apnea, and that RV dilatation followed by a reduction in LV stroke volume is closely associated with the severity of obstructive sleep apnea. The mechanism of heart failure in obstructive sleep apnea appears similar to that in isolated pulmonary regurgitation. Therefore, independent factors affecting LV diastolic dysfunction, such as obstructive sleep apnea, should be evaluated in the management of patients with isolated pulmonary regurgitation to assess cardiac alterations.
An interatrial left-to-right shunt causes RV volume overload, and the coexistence of an ASD or patent foramen ovale can be crucial in refractory heart failure in patients with isolated pulmonary regurgitation. There is a greater prevalence of patent foramen ovale in patients with obstructive sleep apnea than in normal subjects, which could be explained by enhanced effort on the right side of the heart due to transient but frequent elevations of right-sided pressure during apnea.8 An increase in right chamber pressure is generally considered a cause of reopening a previously closed foramen ovale. Although the detailed mechanism remains unclear, the pathophysiology of isolated pulmonary regurgitation with obstructive sleep apnea might favor maintaining the patency of the foramen ovale. Reopening the foramen ovale can trigger hemodynamic deterioration refractory to medical treatment. The experience in this case implies that evaluation of the structure and function of the ventricles, especially LV diastolic dysfunction, is essential to avoid acute hemodynamic derangement and to determine the optimal timing of surgery for isolated pulmonary regurgitation.
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REFERENCES
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- Ansari A. Isolated pulmonary valvular regurgitation: current perspectives. Prog Cardiovasc Dis 1991;33:329–44.[Medline]
- Zucker N, Rozin I, Levitas A, Zalzstein E. Clinical presentation, natural history, and outcome of patients with the absent pulmonary valve syndrome. Cardiol Young 2004;14:402–8.[Medline]
- Tanabe Y, Takahashi M, Kuwano H, Izumi T, Shibata A, Oda E, et al. Long-term fate of isolated congenital absent pulmonary valve. Am Heart J 1992;124:526–9.[Medline]
- Pouget JM, Kelly CE, Pilz CG. Congenital absence of the pulmonary valve. Report of a case in a seventy-three year old man. Am J Cardiol 1967;19:732–40.[Medline]
- Bradley TD, Floras JS. Sleep apnea and heart failure. Part I: obstructive sleep apnea [Review.]. Circulation 2003;107:1671–8.[Free Full Text]
- Fung JW, Li TS, Choy DK, Yip GW, Ko FW, Sanderson JE, et al. Severe obstructive sleep apnea is associated with left ventricular diastolic dysfunction. Chest 2002;121:422–9.[Medline]
- Shivalkar B, Van de Heyning C, Kerremans M, Rinkevich D, Verbraecken J, De Backer W, et al. Obstructive sleep apnea syndrome: more insights on structural and functional cardiac alterations, and the effects of treatment with continuous positive airway pressure. J Am Coll Cardiol 2006;47:1433–9.[Abstract/Free Full Text]
- Beelke M, Angeli S, Del Sette M, Gandolfo C, Cabano ME, Canovaro P, et al. Prevalence of patent foramen ovale in subjects with obstructive sleep apnea: a transcranial Doppler ultrasound study. Sleep Med 2003;4:219–23.[Medline]
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ABSTRACT
INTRODUCTION
