Absent Left and Right Superior Vena Cava and Azygos Continuation of Inferior Vena Cava: A Rare Anomaly of Systemic Venous Return

ABSTRACT: We report a case of a complicated vascular access secondary to systemic venous defects which have not been previously reported. Further evaluation revealed congenital absence of superior vena cava with two brachiocephalic veins draining separately. He also had absence of the hepatic segment of the inferior vena cava with azygos continuation. The patient did not have congenital anomalies of the remaining thoracoabdominal vasculature and viscera.

INVASIVE CARDIOL 2010;22:E159–E161

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Anomalies of the systemic veins are not uncommon, with a persistent superior vena cava,^1,2,4,7 absent right superior vena cava and an interrupted inferior vena cava being most frequent. An understanding of these anomalies is of paramount importance because of the association with various congenital defects. This could pose a potential problem particularly during various cardiovascular procedures in which the repair of the venous anomaly may not be important but access may be complicated by these anomalies. We share an interesting case of a man who presented with palpitations. He underwent electrophysiological evaluation and was found to have a constellation of systemic venous anomalies, which have not been previously reported. Case Report. Our patient was a 59-year-old Caucasian male with no prior history of coronary artery disease, congestive heart failure, hypertension or diabetes who presented with multiple episodes of palpitations. He was found to have electrocardiographic evidence of Wolf Parkinson White (WPW) pattern. He was initially treated with amiodarone without successful conversion and later underwent an electrophysiological evaluation for ablation purposes. The left femoral venous site was accessed with a size 10 French (Fr) triport sheath through which three quadripolar pacing electrode catheters were introduced in an attempt to reach the right atrium, right ventricular apex and atrioventricular junction. However, the catheter was observed going high up in the thorax and returning back to what seemed to be the superior vena cava and then the coronary sinus. Access to the right ventricular apex from the femoral approach was not successful. Another attempt was made with a 7 Fr sheath through which a six size quadripolar pacing electrode was inserted and advanced under fluoroscopic guidance which again could not reach the right ventricle and was left in the coronary sinus. Access to the right ventricle did not seem possible because of the anomalous venous drainage. Utilizing the concealed left posteroseptal accessory pathway, an orthodromic supraventricular tachycardia was easily induced. A pigtail catheter was then inserted into the right femoral vein and advanced under fluoroscopic guidance into the anomalous vein. Radio-iodinated contrast material was injected in order to obtain a venogram. It was observed that no contrast was going directly into the right atrium. This anomalous venous drainage was suspected to be an azygos vein. Systemic venous pressures were measured which confirmed it to be venous and further confirmation was made by measuring oxygen saturations, which were 81% and suggestive of mixed venous blood. For the purpose of ablation a size 8 Fr sheath was inserted into the right femoral artery. A 4 ml tipped deflectable ablation catheter with standard curve was advanced retrograde into the left ventricle and subsequently through the mitral valve into the left atrium and positioned toward the septum. Mapping was performed and two radiofrequency applications were given in that region without success. Because of the distorted venous anatomy a transeptal puncture could not be performed. Any further attempts at ablation were abandoned. CT angiography of the thorax and abdomen was performed for further evaluation of congenital cardiac and vascular defects. Post procedure 3-D maximal intensity projection and volume rendered image reconstruction was performed which revealed a number of systemic venous defects. The inferior vena cava in its abdominal course was found to be on the left side of abdominal aorta and emptied into a dilated azygos vein which was of the same caliber as the inferior vena cava. No intrahepatic portion of the inferior vena cava was identifiable. Three hepatic veins were identified which drained directly into the coronary sinus. There was no superior vena cava and the two brachiocephalic veins drained separately, with the right brachiocephalic vein into the azygos vein and the left into coronary sinus. No hemiazygos vein was identified. The aortic arch demonstrated an aberrant course in which the right subclavian artery coursed posterior to the esophagus from left to right side. The thoracoabdominal vasculature and viscera demonstrated normal anatomy. A transesophageal echocardiogram with bubble study was performed which did not reveal any left or right shunting, but showed remnants of the Eustachian valve in the right atrium. No patent foramen ovale was demonstrated either. Discussion. Systemic venous anomalies occur in less than 2% of the normal population.³ The most frequently seen are persistence of the left superior vena cava1,^2,7 with or without a right superior vena cava, partial anomalous pulmonary venous return and azygos and hemiazygos continuation of an interrupted inferior vena cava.^3,6 Our patient had a constellation of systemic venous defects which have not been previously reported. He had congenital absence of superior vena cava^5,8 with two brachiocephalic veins draining separately. He also had absence of the hepatic segment of the inferior vena cava with azygous continuation.^3,6 The patient did not have congenital anomalies of the remaining thoracoabdominal vasculature and viscera. He had a persistent Eustachian valve in the right atrium with normal valve morphologies and intact interatrial and interventricular septums. Heterotaxic syndromes^1,9 are characterized by failure of right to left differentiation during embryologic development which lead to ambiguity in viceroatrial situs along with anomalies of the systemic and pulmonary venous return. It is further categorized into two subtypes that is left and right atrial appendage isomerism. In patients with left atrial appendage isomerism, the infrahepatic portion of the inferior vena cava is frequently absent and the venous return from the lower part of the body enters the superior vena cava via the azygos vein. In patients with right atrial appendage isomerism, the right and left hepatic veins may enter the ipsilateral sides of the common atrium remaining separate from the inferior vana caval entrance. Polysplenia, ventricle septal defects and pulmonary stenosis are common in left sided atrial appendage isomerism. Asplenia, defects in the atrioventricular canal, extreme pulmonary stenosis, single atrium, Fallot’s tetralogy, anomalous drainage of pulmonary veins are frequently seen in right atrial appendage isomerism. Our patient did not have congenital cardiac and visceral defects commonly seen in patients with left or right atrial appendage isomerism. He also had WPW associated with systemic venous anomalies which has not been previously reported and is frequently seen in Ebstein anomaly of the heart. He was discharged home on metoprolol and flecainide with no symptoms of palpitations. The patient is scheduled to have another attempt at ablation through transseptal approach.

References

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From the Departments of Internal Medicine and Electrophysiology, Wright State University Boonshoft School of Medicine, Dayton, Ohio. The authors report no conflicts of interest regarding the content herein. Manuscript submitted November 10, 2009, provisional acceptance given January 4, 2010, final version accepted February 2, 2010. Address for correspondence: Muhammad Bilal Quraishi, MD, Dayton VA Medical Center, 4100 W. Third Street, Dayton, OH 45428. E-mail: quraishi.bilal@gmail.com