1Department of Cardiovascular Surgery, Tehran University of Medical Sciences, Tehran, Iran; 2Department of Cardiovascular Surgery, Shahrekord University of Medical Sciences, Shahrekord, Iran *Corresponding Author’s e-mail: behshakerian@yahoo.com رتج األذين األمين يف امرأة ابلغة مع إحصار احلزمية اليسرى بهنام �ساكريان وحممد ح�سني مانديغار abstract: Right atrial diverticulum is a very rare anomaly. It is an outpouching arising from the right atrial free wall. Clinical presentations vary widely but some cases are associated with supraventricular tachycardia and atrial flutter/fibrillation. The incidence/prevalence of this anomaly is not available because only a few cases have been reported. We report a 38-year-old female patient who presented to the Heart Clinic, Tehran, Iran in 2019 with a history of dyspnea and chest pain. Electrocardiography revealed left bundle branch block. Following a magnetic resonance imaging study, the patient was diagnosed with a right atrial diverticulum. She underwent surgical resection of the diverticulum. The post-operative course was uneventful and no recurrence of the arrhythmia was detected during the six months of follow-up. To the best of the authors’ knowledge, this combination has not been described in the literature. Keywords: Right Atrium; Diverticulum; Left Bundle Branch Block; Case Report; Iran. يُّب َخاِرِجي ين�ساأ من اجلدار احلر للأُذين الأمين. تتفاوت الأعرا�ض ال�رسيرية تفاوتا كبريا امللخ�ص: رجت الأُذين الأمين هو �سذوذ نادر جًدا. هو َتَ ولكن ترتبط بع�ض احلالت بت�سارع القلب فوق البطيني والرفرفة الأذينية/الرجفان الأذيني. معدل حدوث/انت�سار هذا ال�سذوذ غري معروف لأنه ل يتم الإبلغ ال عن حالت قليلة فقط. نعر�ض هنا حالة مري�سة تبلغ من العمر 38 عاًما َقِدَمت اإىل عيادة القلب، طهران، اإيران يف عام 2019 ولديها تاريخ من �سيق التنف�ض واأمل يف ال�سدر. ك�سف تخطيط كهربية القلب عن اإِْح�سار احُلَزمَية الُي�رسى. مت ت�سخي�ض املري�سة برجت اأذيني اأمين بعد درا�سة الت�سوير بالرنني املغناطي�سي. خ�سعت لعملية ا�ستئ�سال جراحي للرجت وكانت مرحلة ما بعد اجلراحة خالية من امل�ساعفات ومل يتم الك�سف عن اأي تكرار ل�سطراب �رسبات القلب خلل الأ�سهر ال�ستة من املتابعة. على حد علم املوؤلفني مل يتم و�سف هذه التوليفة يف الأدبيات. الكلمات املفتاحية: اأذين اأمين؛ رجت؛ اإح�سار احلزمية الي�رسى؛ تقرير حالة؛ اإيران. Right Atrial Diverticulum in an Adult Woman with Left Bundle Branch Block *Behnam Shakerian1,2 and Mohammad H. Mandegar1 Sultan Qaboos University Med J, November 2020, Vol. 20, Iss. 4, pp. e394–396, Epub. 21 Dec 20 Submitted 15 Apr 20 Revision Req. 11 May 20; Revision Recd. 8 Jun 20 Accepted 24 Jun 20 months before presenting to the hospital. She had no significant history or family history. Cardiovascular system examination did not reveal any murmurs. Electrocardiography (ECG) showed sinus rhythm with LBBB [Figure 1]. All laboratory tests were within normal limits. Transthoracic echocardiography showed an echolucent space around the RA approximately 2 × 3 cm in size that was connected to the RA [Figure 2]. Contrast echocardiography was suggestive of an RA diverticulum. The tricuspid valve was normal without significant annular dilation. No stenosis or abnormal displacement of the tricuspid valve leaflets was detected and no significant regurgitation of the tricuspid valve was found. No other cardiac anomalies were found. The left ventricle ejection fraction was 55%. Cardiac magnetic resonance imaging (MRI) showed a 25.2 × 16.5 × 35 mm pouch in the inferior wall of the RA [Figure 3]. The pericardium was visualised without any abnormality. The diverticulum caused no haemodynamic effects. The patient was evaluated by a cardiac team and Single right atrial (ra) diverticulum, a rare congenital anomaly, is a saccular structure that protrudes from an otherwise normal RA.1 Most of the diverticula originate from the atrial free wall. The aetiology of this anomaly is not yet clearly understood. The size of the diverticulum is variable. This case report describes a patient with a rare atrial diverticulum and left bundle branch block (LBBB) who underwent surgery successfully. The presence of (LBBB) has not been reported in the English literature to date. Case Report A 38-year-old female patient presented to the Heart Clinic, Tehran, Iran in 2019 with a history of palpitation, dyspnoea on exertion and recurrent chest pain accompanied by three episodes of syncope that occurred two years prior to presentation. She received imipramine for depression but the symptoms did not improve. Therefore, she discontinued it six This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License. https://doi.org/10.18295/squmj.2020.20.04.019 case report https://creativecommons.org/licenses/by-nd/4.0/ Behnam Shakerian and Mohammad H. Mandegar Case Report | e395 due to arrhythmias (LBBB), high risk of thrombus formation and the risk of progression, the patient was scheduled for surgery. Through a median sternotomy, cardiopulmonary bypass was established with aortic and bicaval cannulation. The diverticulum was visible, arising from the free wall of the RA, discrete from the caval veins, coronary sinus and tricuspid valve. Intra- operative findings were consistent with the features of a diverticulum [Figures 4A & B]. There was no thrombus in the diverticulum. Resection of the diverticulum was done and cryoablation of the diverticulum neck was performed successfully. The RA was reconstructed by direct sutures. Histologic examination revealed a thin wall with areas of fibrosis covered by cuboidal cells without muscular tissue suggestive of an atrial diverticulum [Figure 4C]. The postoperative course was uneventful and sinus rhythm was maintained. She was discharged on the sixth postoperative day. After discharge, she remained asymptomatic with no arrhythmias. The patient was still asymptomatic six months after the operation. Discussion RA diverticulum is a very rare congenital anomaly with an unclear aetiology. Bailey described the excision of a right atrial diverticulum for the first time in 1953.2 RA diverticulum is a structure that protrudes from the RA free wall but does not include all layers of the atrial wall.3 A diverticulum can be detected at any time between fetal and adult life and the size varies with the largest being reported at 13 × 8.9 × 13.8 cm.4 This anomaly is usually asymptomatic, but it can be associated with atrial arrhythmia, chest pain, peripheral oedema, shortness of breath, fatigue and jugular engorgement. The incidence of arrhythmia and the clinical outcome of the patients have not been reported to date. Arrhythmia may be caused by abnormal impulses generated within the diverticular wall. Supraventricular arrhythmia has been reported in patients, which is associated with a high risk of morbidity and mortality due to cardiac dysfunction and increased risk of stroke and heart failure.5,6 The current patient did not have any supraventricular arrhythmias but she did have LBBB on ECG. While antidepressant agents can cause cardiac arrhythmias, this was not considered for the current patient as she had stopped taking imipramine six months before presenting to the hospital. LBBB is usually associated with coronary artery disease, hypertension and cardiomyopathy. LBBB is usually pathological and is rare in young individuals.7 In case of cardiac arrhythmia, structural anomalies of the atrium should be suspected. LBBB can progress to complete heart block. The reason for arrhythmia was not clear in the patient but the authors believe that it was caused by structural disorientation of the conduction system, which may allow ample electrical communication Figure 1: Electrocardiogram of a 38-year-old female patient showing left bundle branch block. Figure 3: Cardiac magnetic resonance image of a 38-year-old female patient showing the finding of a right atrial diverticulum (white arrow). Figure 2: Echocardiography of a 38-year-old female patient showing a right atrial diverticulum. Right Atrial Diverticulum in an Adult Woman with Left Bundle Branch Block e396 | SQU Medical Journal, November 2020, Volume 20, Issue 4 between the atrium and ventricle without a well- defined accessory pathway. This is supported by the fact that a normal sinus rhythm resumed when the diverticulum was removed. The slow flow in the diverticulum is likely to predispose a patient to clot formation and pulmonary embolisation. The incidence of sudden death is approximately 6%.8 A right atrial diverticulum is usually diagnosed by echocardiography but computed tomography and MRI imaging are also used. Differential diagnosis includes Ebstein’s anomaly, aneurysms, pericardial cysts and mediastinal tumours. Although the optimal treatment of this rare anomaly is not clear, surgical excision is the therapy of choice and indicated in arrhythmia, thromboembolism, progressive RA dilatation and compressive symptoms; therapeutic outcomes are good. Other options include resection of the diverticulum with an endoscopic linear cutter through a limited right thoracotomy, but this device is not available in the authors’ centre. Transcatheter ablation through the whole diverticulum is crucial for the successful treatment of arrhythmia. Due to a wide connection between the RA diverticulum and right ventricle, transcatheter ablation may not be complete, which may result in recurrence. Conclusion A combination of RA diverticulum and LBBB has not been reported in the literature to date as was presented in the current case. Surgical excision of the diverticulum removes the substrate and cures the conduction abnormality. Patients do not usually experience the recurrence of conduction abnormality after excision of the diverticulum. References 1. Borgohain S, Malik L, Prasad S, Gupta A, Grover V, Gupta VK. Case of single right atrial diverticulum and review of etiology and management. Asian Cardiovasc Thorac Ann 2013; 21:592–5. https://doi.org/10.1177/0218492312458787. 2. Bailey CP. Surgery of the heart. Philadelphia, PA, USA: Lea & Febiger, 1955. Pp. 413. 3. Chockalingam A, Alagesan R, Gnanavelu G, Dorairajan S, Subrananiam T. Right atrial aneurysm in adults--Report of three cases and review of literature. Echocardiography 2004; 21:639–43. https://doi.org/10.1111/j.0742-2822.2004.03156.x. 4. Yuan G, Yan BP, Hu J, Wang S, Sun JP. Compressive giant right atrial diverticulum. Eur Heart J Cardiovasc Imaging 2016; 17:1065. https://doi.org/10.1093/ehjci/jew113. 5. Hagens VE, Ranchor AV, Van Sonderen E, Bosker HA, Kamp O, Tijssen JG, et al. Effect of rate or rhythm control on quality of life in persistent atrial fibrillation. Results from the Rate Control versus Electrical Cardioversion (RACE) Study. J Am Coll Cardiol 2004; 43:241–7. https://doi.org/10.1016/j. jacc.2003.08.037. 6. Van Gelder IC, Hagens VE, Bosker HA, Kingma JH, Kamp O, Kingma T, et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med 2002; 347:1834–40. https://doi.org/10.1056/ NEJMoa021375. 7. Sinha A, Shelter UB, Pinchani M, Sayyed AA, Sintia NK. The enigma of intermittent left bundle branch block: A case report. Pravara Med Rev 2013; 5:32–4. 8. Binder TM, Rosenhek R, Frank H, Gwechenberger M, Maurer G, Baumgartner H. Congenital malformations of the right atrium and the coronary sinus: An analysis based on 103 cases reported in the literature and two additional cases. Chest 2000; 117:1740–8. https://doi.org/10.1378/chest.117.6.1740. Figure 4: A & B: Intraoperative view of the heart of a 38-year-old female patient showing a right atrial (RA) diverticulum (white arrow). C: Haematoxylin and eosin stain at x100 magnification of the RA diverticulum showing a thin wall with areas of fibrosis covered by cuboidal cells without muscular tissue. https://doi.org/10.1177/0218492312458787 https://doi.org/10.1111/j.0742-2822.2004.03156.x https://doi.org/10.1093/ehjci/jew113 https://doi.org/10.1016/j.jacc.2003.08.037 https://doi.org/10.1016/j.jacc.2003.08.037 https://doi.org/10.1056/NEJMoa021375 https://doi.org/10.1056/NEJMoa021375 https://doi.org/10.1378/chest.117.6.1740