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Aortic Regurgitation due to Commissural Dehiscence of the Aortic Valve

Toshihiro Fukui

Commissural dehiscence of the aortic valve is a rare cause of aortic regurgitation. We report a 53-year-old malewho had progressive aortic regurgitation and aortic root dilatation. A flap or intimal tear of the proximal aorta wasabsent with echocardiography and computed tomography. Transesophageal echocardiography revealed prolapse ofthe right and left coronary cusps with no intimal flap in the ascending aorta. During the operation, there was nodissection or intramural hematoma in the ascending aorta. However, there was dehiscence of the commissurebetween the right and left coronary cusps of the aortic valve. Aortic root and ascending aortic replacements weresuccessfully performed. Commissural dehiscence of the aortic valve should be taken into account when prolapse ofthe aortic cusp is the cause of aortic regurgitation.

Introduction: Commissural dehiscence of the aortic valve is a rare cause of aorticregurgitation. This condition has been documented in only a few casereports  [1-5].  Commissural  dehiscence  of  the  aortic  valve  isoccasionally found intraoperatively because preoperative diagnosis ofthis condition is difficult. We report a case of commissural dehiscenceof  the  aortic  valve  that  caused  aortic  regurgitation  and  aortic  rootdilatation.CaseA 53-year-old man was admitted to our hospital with congestiveheart failure. He had dyspnea on exertion 1 month before referral toour  hospital.  His  symptoms  improved after  use  of  diuretic  drugs.Transthoracic   echocardiography   demonstrated   severe   aorticregurgitation and moderate mitral regurgitation with left ventriculardilatation (left ventricular diastolic dimension, 67 mm; left ventricularsystolic  dimension,  50  mm).  Contrast-enhanced  computedtomography  (CT)  showed  dilatation  of  the  aortic  root  (sinus  ofValsalva, 45 mm). A flap or intimal tear of the proximal aorta wasabsent   with   echocardiography   and   CT.   Transesophagealechocardiography (TEE) was performed to assess the cause of aorticregurgitation.  TEE  revealed  prolapse  of  the  right  and left  coronarycusps (Figure 1) with no intimal flap in the ascending aorta. Surgerywas planned after medical control of heart failure.Median  sternotomy  was  performed.  When  the  pericardium  wasopened,  serous effusion  was  observed.  Moreover,  tight  adhesionbetween  the  ascending  aorta  and  pulmonary  artery  was  observed.Cardiopulmonary  bypass  was  performed  with  ascending  aortic  andbicaval venous cannulations.Figure 1: Transesophageal echocardiogram demonstrating prolapseof the right and left coronary cusps with no flap in the ascendingaorta.After the adhesion around the ascending aorta was dissected, anaortic  clamp  was  applied  and  cardiac  arrest  was  obtained.  Mitralannuloplasty with a semi-rigid ring (size, 30 mm) was performed. Thebody  temperature  was  decreased  to  25°C,  systemic  perfusion  wastemporarily arrested, and retrograde cerebral perfusion was started.The ascending aorta was resected, and replaced with a 26-mm Triplexgraft  (Vascutek  Terumo,  Tokyo,  Japan)  with  one  branch. Aftercompletion of distal aortic anastomosis, systemic perfusion throughthe side branch of the graft was resumed. There was no dissection orintramural  hematoma  in  the  ascending  aorta.  However,  there  wasdehiscence  of  the  commissure  between  the  right  and left  coronarycusps  of  the  aortic  valve  (Figure  2).  Valve leaflets  were  slightlyatherosclerotic, and the aortic wall was normal. We performed aorticroot  replacement  with  a  commercially  available  composite  valvedconduit  (25–28  mm;  Carboseal,  CarboMedics,  Austin,  TX). TheOkamoto and Fukui

Discussion: Commissural dehiscence of the aortic valve is a rare cause of aorticregurgitation. Aortic regurgitation sometimes occurs secondary toacute aortic dissection. Aortic leaflet prolapse occurs when dissectionextends into the aortic root, and disrupts normal attachment of leafletsto the aortic wall. In the present case, prolapse of the right and leftaortic leaflets occurred by dehiscence of the commissure between theright and left aortic cusps. This condition has been documented in onlya few case reports [1-5]. Although the cause of aortic commissuraldehiscence is unknown, hypertension is considered to be the mostlikely cause [3].Aortic valve replacement with or without fixation of the dehiscentaortic wall is a common procedure [1-3]. Another treatment of choiceis aortic root replacement [1,4,5]. In the present case, aortic rootreplacement with a valved conduit was performed because the aorticroot and ascending aorta were dilated. An aortic valve-sparingoperation may be an alternative procedure in patients without heartfailure and other cardiac procedures (mitral valve annuloplasty andascending aortic replacement).In conclusion, commissural dehiscence of the aortic valve is a rarecause of aortic regurgitation. We should take this condition intoaccount when prolapse of the aortic cusp is the cause of aorticregurgitation.