Inferior Sinus Venosus Type Atrial Septal Defect Initially Presenting Pulmonary Hypertension on Transthoracic Echocardiography

Hyon Joung Cho, MD, Wook-Jin Chung, MD, Jeong Min Bong, MD, Kwen-Chul Shin, MD, Mi-Seung Shin, MD, Woong Chol Kang, MD, Seung Hwan Han, MD, Chan Il Moon, MD, Kwang Kon Koh, MD, Tae Hoon Ahn, MD, In Suck Choi, MD and Eak Kyun Shin, MD Division of Cardiology, Department of Internal Medicine, Gachon University Gil Hospital, Incheon, Korea

Inferior sinus venosus type atrial septal defect (ASD) is a rare congenital cardiac deformity that occurs between the inferior vena cava and right atrium. Inferior sinus venosus defect is difficult to diagnose through transthoracic echocardiography because of its location which is infero-posterior to the fossa ovalis. Increasing pulmonary arterial pressure and pulmonary vascular resistance in patients with sinus venosus defect usually occur earlier than other types of ASD. We report a case of 19- year-old man who presented exertional dyspnea due to inferior sinus venous type ASD with mild pulmonary hypertension. In this case, we found clues from slight diastolic flattening of interventricular septum and shortened acceleration time of right ventricular outflow tract on initial transthoracic echocardiography, leading right heart catheterization and transesophageal echocardiography to reveal this rare type of ASD.

KEY WORDS: Echocardiography·Atrial septal defect·Pulmonary hypertension.

Introduction atrium and ventricle and slight diastolic flattening of interven- Inferior sinus venosus type atrial septal defect (ASD) is rare tricular septum (Fig. 1). However, pulmonary arterial systolic and difficult to depict by transthoracic echocardiography pressure (PAsP) estimated from tricuspid regurgitation velocity (TTE) because of its infero-posterior location of the fossa (TRV) was normal (Fig. 2A). However mean pulmonary ovalis.1)2) So, this defect is frequently missed with conventional arterial pressure (mPAP) by simplified Mahan’s equation TTE views. We report a case of 19-year-old man with inferior (mPAP=80-[RVOT AT 0.5]) calculating from acceleration sinus venous type ASD from the clue only from slight dias- time (AT) of right ventricular outflow tract (RVOT) was signi- tolic flattening of interventricular septum and mild pulmonary ficantly increased to 35.6 mmHg (Fig. 2B). hypertension (PH). Although mPAP showed mild PH, we recommended the right heart catheterization to determine the cause of symptom. Case It demonstrated significant oxygen step-up between superior A 19-year-old man without any specific past medical history vena cava and inferior vena cava (oxygen saturation of superior came to the clinic, complaining of dyspnea on exertion for 4 vena cava; 73.2%, inferior vena cava; 89.7% and main pul- years. He visited several hospitals before, but they couldn’t monary artery; 84.9%), increased pulmonary blood flow find out the cause of his symptoms. His symptom has been (Qp/Qs=1.8) and increased mPAP (26 mmHg). To find out aggravating for the recent 3 months. An electrocardiogram the site of the shunt, we performed the transesophageal echo- showed normal sinus rhythm and QRS axis. cardiography (Fig. 3). It confirmed an inferior sinus venosus TTE showed no specific findings except mildly dilated right type ASD. ASD patch closure operation was performed for

Received: November 10, 2008 Accepted: February 5, 2009 Address for Correspondence: Wook-Jin Chung, Division of Cardiology, Department of Internal Medicine, Gachon University Gil Hospital, 1198 Guwol-dong, Namdong-gu, Incheon 405-760, Korea Tel: +82-32-460-8305 (Office), +82-32-460-3845 (Lab.), Fax: +82-32-460-8305, E-mail: [email protected]

25 Journal of Cardiovascular Ultrasound 17｜March 2009

A B Fig. 1. 2D views of transthoracic echocardiography. A: Parasternal short axis view at mid-LV level showed slight diastolic flattening of interventricular septum (arrows). B: Apical 4 chamber view showed mildly dilated right ventricle and atrium. LV: left ventricle.

A B Fig. 2. Doppler findings. A: PAsP from TRV was within normal range. B: RVOT AT was 88.7 msec and calculated mPAP from the simplified Mahan’s equation (mPAP= 80-[RVOT AT×0.5]) was 35.6 mmHg (B). PAsP: pulmonary arterial systolic pressure, TRV: tricuspid regurgitation velocity, RVOT: right ventricular outflow tract, AT: acceleration time, mPAP: mean pulmonary arterial pressure.

Discussion Generally, sinus venosus type ASD is a rare cardiac abnor- mality in adults.1) In General, the patient may remain asymp- tomatic and undiagnosed until the fourth decade of life when clinical signs and symtoms of pulmonary hypertension may develop. And pulmonary hypertension and increased pulmonary vascular resistance occur at an earlier age in patients with a sinus venosus defect than other types of ASD and are clearly related to NYHA functional class.3) And these defects are frequently missed, and too difficult to visualize with conventional two-dimentional echocardiography views.2)4) Fig. 3. Transesophageal echocardiography. Color Doppler imaging Although not taking in this case, agitated saline contrast showed a defect at the extremely posterior portion of interatrial septum occasionally maybe helpful to detect left to right shunt even with left to right shunt flow. in TTE.5) symptomatic hemodynamically significant left to right shunt TRV is usually the primary method for determining actual (Fig. 4). The patient tolerated the operation and had an pulmonary pressure. However, TRV usually varies with respi- uneventful recovery. ration and was occasionally confused with high velocities

26 Inferior Sinus Venosus Type ASD with PH｜Hyon Joung Cho, et al.

IVC

Fossa ovalis

ASD: sinus venosus type, IVC area ASD GA-fixed autopericardial patch closure Fig. 4. Patch repair of inferior sinus venosus type atrial septal defect (ASD) with autopericardium. The defect was located in inferior vena cava area and size was 1.5 cm. CS: coronary sinus, IVC: inferior vena cava. from aortic stenosis or mitral regurgitation. Although slight unexplained dyspnea on exertion, physicians and sonogra- diastolic flattening of interventricular septum was observed phers should have a clinical suspicion of PH and should not at two dimensional view, TRV showed within normal range overlook a subtle clue which may lead to find an critical in this case. Because TRV has many caveats like this case, we diagnosis for the patient. should evaluate alternative methods such as simplified Mahan’s equation in the case of clinically suspected PH. References Nonetheless, RVOT AT using simplified Mahan’s equation 1. Arnheid KS, Andre L, Rene P, Peter B. Inferior sinus venosus defect is not perfect and can be dependant on cardiac output and associated with incomplete cor triatriatum dexter and patent foramen ovale. Eur J Echocardiogr 2006;7:239-42. heart rate. Disappointingly, this case showed such discre- 2. Coon PD, Lang RM. Improved visualization of sinus venosus atrial septal pancy (about 9.6 mmHg) between mPAP from simplified defects in adults from the transthoracic approach. J Am Soc Echocardiogr Mahan’s equation and mPAP through right heart catheteri- 2006;19:1072. zation. So, right heart catheterization would be often 3. Vogel M, Berger F, Kramer A, Alexi V, Lange PE. Incidence of secondary pulmonary hypertension in adults with atrial septal or sinus venosus defects. required to confirm the presence of PH, establish the specific Heart 1999;82:30-3. diagnosis, and determine the severity of PH. 4. Pascoe RD, Oh JK, Warnes CA, Danielson GK, Tajik AJ, Seward JB. Actually our patient had taken a long time to diagnosis. In Diagnosis of sinus veosus atrial septal defect with transesophageal this case, we found the clue only from slightly diastolic echocardiography. Circulation 1996;4:1049-55. 5. Oh KJ, Chung WJ, Shin MS, Han MY, Kang WC, Choi KL, Yang flattening of IVS because mildly dilated right ventricle and PS, Kim SY, Ahn TH, Shin EK. Unroofed coronary sinus associated with atrium are usually common findings in the pediatric and persistent left superior vena cava;detection by agitated saline contrast teen ages. Therefore, when encountering a patient with echocardiography. J Kor Soc Echocardiogr 2004;12:49-53.