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Secundum Atrial Septal Defect: Surgical Closure

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Published: Wed, 08 Aug 2018

Surgical closure of secundum atrial septal defect in a patient with atrial situs solitus and interrupted inferior vena cava: report of 2 cases

Key Words: Interrupted inferior vena cava, Situs solitus, Atrium septal defects, limited skin incision

Abstract

The occurrence of an interrupted inferior vena cava (IVC) in setting of atrial situs solitus is relatively rare. Here, we reported two cases of the surgical closure of secundum atrium septal defects (ASDs) in patients with atrial situs solitus and an interrupted IVC. The first case was a 7-year-old boy with a secundum ASD without the posterior rim whose interrupted IVC and azygos continuation had been preoperatively diagnosed by the echocardiography and cardiac catheterization. The operation was safely performed using a large-sized venous drainage cannula from the superior vena cava (SVC). The second case was a 2-year-old boy with a secundum ASD without the superior rim whose interrupted IVC was not diagnosed at the preoperative examination. The operation was performed through a median partial sternotomy via a 5.0cm limited skin incision, so direct inspection of the SVC was not clearly obtained. A cardiopulmonary bypass was established using the recommended size of venous drainage cannulae; however, the SVC could not be removed without elevating the SVC pressure. As a result, the ASD was closed directly under sucking the venous return from the SVC without snaring it. Post-operative computed tomography detected an interrupted IVC with azygos continuation and a persistence of both supracardinal veins, known as a double IVC.

Introduction

Whereas an interrupted inferior vena cava (IVC) because of the absence of its hepatic segment is mainly noted in patients with heterotaxy syndrome, the occurrence of an interrupted IVC within the atrial situs solitus is reported as ranging from 0.08 to 0.1% [1,2,3]. In these patients, cardiac malformations are frequently associated, and the main types of abnormalities include atrial septal defects (ASDs, 10.5 %) and ventricular septal defects (7.5 %) [1].

Although this systemic venous anomaly provides no symptoms by itself, it seems to be relevant in cardiac surgery, especially in procedures that require approaches through the right atrium. Here, we reported two cases of the surgical closure of secundum ASD in patients with atrial situs solitus and interrupted IVC, focusing on perioperative findings and associated issues.

Case

Case 1

A clinically asymptomatic 7-year-old boy (body weight, 22 kg; height, 125 cm) with an ASD secundum, which was detected at the age of 10 months, was admitted for surgical closure of the lesion. Device ASD closure by catheter intervention was contraindicated because of the absence of the posterior rim. Preoperative echocardiography revealed an atrial sinus solitus with an 18 by 21-mm ASD secundum without the posterior rim and relative valvular pulmonary stenosis. Also, interrupted IVC was suspected because drainage of the IVC into the right atrium was not detected. Cardiac catheterization to assess the indication for surgical pulmonary valvotomy showed a systemic and pulmonary blood flow ratio of 3.14 and pull-buck pressure gradient of 10 mmHg from the right ventricle to the main pulmonary artery. Furthermore, no hepatic segment of the IVC was detected; thus, an interrupted IVC with azygos continuation was confirmed (Fig. 1).

Through the median full sternotomy, a cardiopulmonary bypass was established using arterial cannulation through ascending aorta perfusion with a 16-Fr cannula and venous drainage from the superior vena cava (SVC) and the hepatic vein using 28 and 20 Fr cannulae, whereas recommended cannulae sizes were 20 and 24 Fr, respectively. The ASD secundum was closed directly through the right atriotomy under moderate hypothermia and cardioplegic arrest. The operation was completed without any issues.

Case 2

A clinically asymptomatic 2-year-old boy (body weight, 10 kg; height, 81 cm) had recently been diagnosed with a large ASD secundum without the superior rim. Further examination revealed an atrial sinus solitus, an 18 by 18-mm ASD secundum without the superior rim, and a bicuspid aortic valve. However, an interrupted IVC was not diagnosed.

Through a median partial sternotomy via a limited skin incision (50mm in length), a cardiopulmonary bypass was established using arterial cannulation through ascending aorta perfusion with a 12-Fr cannula and venous drainage from the SVC and hepatic vein, although it was thought to be an IVC at that time, using the recommended sizes of 16 and 18 Fr cannulae. During the surgery, the SVC was attempted to be snared, but it could not be because of the elevating SVC pressure. The depth of cannula and the location of snaring were repeatedly changed without resolving this issue; therefore, the SVC was left without being snared. The ASD secundum was closed directly under moderate hypothermia and cardioplegic arrest with sucking the venous return from the SVC. Weaning off from cardiopulmonary bypass was uneventful, and the operation was completed without any issues. Post-operative computed tomography showed an interrupted IVC with azygos continuation and a persistence of both supracardinal veins, known as double IVC (Fig. 2).

On medical check-up at the outpatient clinic one year after discharge, advanced sick sinus syndrome was detected by electrocardiography. 24-Hour Holter electrocardiography monitoring showed that the total number of heartbeats was 142,036 per day, 8 beats of isolated premature atrial contractions, and had no evidence of premature ventricular contractions or more than 2.5 seconds of sinus pose.

Discussion

Like the first presented case, an interrupted IVC with azygos continuation can usually be diagnosed by preoperative echocardiography [1], which can be easily treated at the establishment of a cardiopulmonary bypass by selecting adequately-sized venous cannulae. If it is not preoperatively diagnosed, direct intra-operative inspection usually makes the diagnosis possible. However, the cosmetic outcome must be taken into consideration during surgical ASD repair as well as secure defect closure after the popularization of percutaneous device closure, like in the second case. Therefore, a limited skin incision with partial sternotomy was selected for this patient, which unfortunately interrupted clear observation of the SVC.

Selection of large sized SVC drainage cannula should have been considered first during inadequate venous drainage, however, which was deferred because the total cardiopulmonary bypass was easily established as long as the SVC was not snared. As is our policy, the IVC is not snared during the closing of the ASD secundum in order to obtain a certain identification of the posterior rim. Therefore, the tip of the IVC drainage cannula was positioned at the IVC around the right atrial junction for sufficient drainage of both the IVC and hepatic venous blood flow. As a result, such a maneuver enabled the establishment of a total cardiopulmonary bypass with small-sized SVC drainage cannula and eventually large “hepatic vein” cannula.

As shown in Case 2, an anomalous IVC is known to accompany various rhythm disorders, though only a few cases have been reported [4,5]. One of the causes of rhythm disorders is the degeneration of the atrial muscle around the sinus node, which might occur as a result of a local volume overload on the sinus node by the presence of azygos continuation. Although the total number of heart beats was well maintained and more than 2.5 seconds of a sinus pose was not observed until now, a scheduled follow-up was mandatory for early detection of further advancement of the sinus node dysfunction.

In summary, two surgical experiences of secundum ASD associated with an interrupted IVC with azygos continuation were reported. Under partial sternotomy via limited skin incision, precautions should be taken to detect the presence of this venous anomaly if venous drainage from the SVC is not adequately obtained using cannula of the recommended size.


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