Double-sided superior vena cava: developmental considerations associated with the thymic veins / Vena cava superior de doble cara: consideraciones de desarrollo asociadas con las venas tímicas

SUMMARY: The superior vena cava is usually located only on the right side, but persistence of the left superior vena cavais observed in about 0.3 to 0.5 % of adults. A routine dissection of the cadaver of a 91-year-old Japanese female, whose cause of death was sepsis due to cholecystitis, was performed at Nagasaki University and revealed a double-sided superior vena cava. On the right side, the superior vena cava opened to the right atrium, while on the left, it opened into the extended coronary sinus. Veins in the left head, neck and upper limb regions joined to form the persistent left superior vena cava, with eventual drainage into the expanded coronary vein. An anastomosing branch occurred between each superior vena cava, and two thymic veins opened to the anastomosing branch. The azygos vein in the azygos venous system opened into the right superior vena cava, whereas a hemi-azygos vein opened into the azygos vein. The accessory hemi-azygos vein also opened into the azygos vein and opened cranially into the left superior vena cava. The left supreme intercostal vein also opened into the left superior vena cava. Several studies have reported a persistent left superior vena cava and the various considerations for its occurrence. Here, we propose a new hypothesis for the embryonic development of the persistent left superior vena cava with the thymic vein. This hypothesis essentially states that the left brachiocephalic vein fails to mature due to inadequate venous return from the thymic vein during the embryonic period, and the left superior vena cava then remains to maintain venous return from the left head, neck and upper limb. We also discuss the clinical significance of the persistent left superior vena cava.

RESUMEN: Usualmente la vena cava superior se localiza solo en el lado derecho, sin embargo en aproximadamente 0,3 a 0,5 % de los adultos se observa la persistencia de la vena cava superior izquierda. En la Universidad de Nagasaki se realizó una disección de rutina del cadáver de una mujer japonesa de 91 años, cuya causa de muerte fue sepsis debido a una colecistitis. El cuerpo presentaba una vena cava superior doble. En el lado derecho, la vena cava superior llegaba al atrio derecho, mientras que en el lado izquierdo drenaba al seno coronario. Las venas de las regiones de la cabeza, el cuello y del miembro superior izquierdo formaban la vena cava superior izquierda persistente, con drenaje hacia la vena coronaria. Se observó una rama anastomótica entre cada vena cava superior y dos venas tímicas drenaban a la rama anastomótica. La vena ácigos drenaba a la vena cava superior derecha, mientras que una vena hemiácigos drenaba a la vena ácigos. La vena hemiácigos accesoria también drnaba en la vena ácigos y cranealmente lo hacia la vena cava superior izquierda. La vena intercostal suprema izquierda drenaba en la vena cava superior izquierda. Varios estudios han informado una vena cava superior izquierda persistente y las diversas consideraciones para su aparición. Aquí, proponemos una nueva hipótesis para el desarrollo embrionario de la vena cava superior izquierda persistente con la vena tímica, que esencialmente establece que la vena braquiocefálica izquierda no se dearrolla debido a un retorno venoso inadecuado de la vena tímica durante el período embrionario, y se mantiene la vena cava superior izquierda para el retorno venoso de la cabeza, el cuello y el miembro superior izquierdo. Además se informa de la importancia clínica de la persistencia de la vena cava superior izquierda.

Anomalous atrium associated with persistent left superior vena cava.

Persistent left superior vena cava (PLSVC) is the most common venous anomaly with an incidence of 0.3-0.5% in the general population. Here, we report a rare case of PLSVC with anomalous atrium in a cadaver during the student's dissection session at the University of Tsukuba. In this case, the coronary sinus had merged with the right atrium to form an enlarged sac-like structure and received systemic venous flow including inflow from the PLSVC. The roof of the coronary sinus with the right atrium was thicker than that of the control cases. We further found that the distance between the sinoatrial node and the opening of the coronary sinus was slightly more than half of that in control cases. This variant appears interesting and is worth reporting for developmental and clinical consideration.

Autopsy findings of an isolated persistent left superior vena cava in an intrauterine dead fetus.

Persistent left superior vena cava (PLSVC) is one of the cardiac system abnormalities with a 0.3-0.5% incidence and caused by inadequate obliteration of the left anterior cardinal vein during embryonic development. Prognosis of PLSVC is generally assumed to be good if it is not accompanied by other cardiac system abnormalities. During the routine ultrasound control of a patient at 25th week of pregnancy at the Obstetrics and Gynecology Department of Mersin University, PLSVC anomaly was detected in an intrauterine fetus. Then, intrauterine death occurred and after removal of the deceased fetus, PLSVC diagnosis was confirmed by autopsy. According to the autopsy findings, right superior vena cava (SVC) and azygos vein were found in normal course. PLSVC opened into the right atrium via enlarged coronary sinus. There was no connection between the two SVCs. On the left side of posterior mediastinum, instead of hemiazygos or accessory hemiazygos veins, a vein symmetrical to azygos was opened into PLSVC, similar to the one on the right. No other cardiac anomaly associated with PLSVC or any other pathology in the other parts of body that could be responsible for death was discovered during autopsy. There was no evidence indicating that PLSVC played any role in intrauterine exitus of the present case. However, as mentioned in the literature, the ectopic beats in the atrium wall of patients with isolated PLSVC and enlarged coronary sinus may lead to pathologies in the conduction system of the heart. Considering the intrauterine death of an isolated PLSVC case associated with cardiac conduction pathologies, we recommend that the common assumption of 'isolated PLSVC is not associated with death' should be reviewed by studies on large series and even intrauterine cases should be closely monitored for cardiac arrhythmia.