Iatrogenic diversion of IVC to left atrium after surgical closure of ASD.

Iatrogenic diversion of the inferior vena cava (IVC) to the left atrium during surgical closure of an atrial septal defect (ASD) is a very rare complication in the era of cardiopulmonary bypass. The eustachian valve could be mistaken for the margin of the ASD. We report a case with this complication after closure of a sinus venosus ASD of the IVC type.

INTRODUCTION

Iatrogenic right-to-left shunting is a rare complication of repaired acyanotic congenital heart disease. This complication was seen in the era before cardiopulmonary bypass when the Eustachian valve was mistaken for the inferior rim of the atrial septum. It is rarely encountered in current surgical practice. We report a case of iatrogenic diversion of the inferior vena cava (IVC) to the left atrium (LA) after closure of a sinus venosus atrial septal defect (ASD) of the IVC type.

CASE REPORT

A 10-year-old girl presented to our clinic with complaints of dyspnea on exertion and cyanosis of extremities after exertion. She had undergone surgical closure of IVC type of sinus venosus ASD 2 years ago. After surgery she had an episode of sudden onset stroke from which she recovered completely. The child was evaluated multiple times at the primary center and echocardiogram was done that apparently showed intact atrial septal patch with no other abnormality.

On clinical examination, she was noted to have a central cyanosis with systemic saturation of 85%. Her heart rate was 84/ min and her blood pressure was 110/70 mm Hg. Clinically there was no auscultatory abnormality. Her electrocardiogram was normal. Her operative notes mentioned that after rerouting the right lower pulmonary vein to the LA, the fenestrations in the atrial septum were divided and enlarged to make a large defect that was then closed with a pericardial patch. Echocardiogram revealed a small fenestration in the ASD patch with left to right shunt. The superior vena cava (SVC) was seen draining normally into the right atrium (RA) and the pulmonary veins were seen draining to the LA. But the IVC flow could not be definitely documented draining to the RA [Figure 1]. A contrast (agitated 5% glucose saline) echocardiogram was performed from the venous access in the lower limb. It showed appearance of the contrast first in the LA and subsequent filling of all four cardiac chambers suggestive of drainage of the IVC into the LA [Figures 2a and 2b]. Her serum hemoglobin was 15 gm% and her packed cell volume (PCV) was 52%.

Figure 1

Subcostal two-dimensional echocardiographic short axis view with color doppler showing a suggestion of IVC flow being directed to the left atrium

Figure 2

(a) Contrast echocardiogram in apical four chamber view demonstrating initial appearance of saline contrast in the left atrium and (b) apical four chamber view demonstrating subsequent appearance of saline contrast in all chambers

She was taken up for a diagnostic cardiac catheterization. An arterial blood gas sample taken though a radial artery showed a PaO2 of 105 mm Hg on FiO2 of 40%, suggestive of hypoxemia. A right femoral venous access was taken with a 6F sheath. A 6F Judkins right coronary (JR) 3.5 catheter was passed though the IVC and was seen directly entering the LA. The JR 3.5 was exchanged for a pigtail catheter that was placed in the IVC just below the diaphragm. A contrast angiogram done in anteroposterior (AP) and left anterior oblique with cranial angulation (LAO Cr) showed the contrast entering the LA directly through the IVC and a small fenestration in the ASD patch through which the contrast filled the RA [Figure 3]. The SVC was entered after crossing the fenestration and entering the RA. Angiogram in the SVC showed its normal drainage into the RA with no spill over into the LA. The child was referred for surgery with the plan to redo the atrial patch directing the IVC to the RA.

Figure 3

IVC angiogram left anterior oblique view with cranial angulation demonstrating flow of the contrast directly into the left atrium from the IVC with a small fenestration at the upper end of the patch

DISCUSSION

Diversion of the inferior vena cava into the left atrium during operative repair of low lying secundum type atrial septal defects was reported in 1957 by Bedford et al.[1] Multiple case reports have later described iatrogenic diversion of IVC flow to the LA after surgical incorporation of the Eustachian valve of the IVC in the repair of a low-lying ASD.[2-6] It has also been reported after closure of sinus venosus defect of the inferior vena caval type.[4] These defects are liable to be incompletely closed at the lower end, or when sutured under tension the repair may disrupt postoperatively.[5] This complication was more frequent before the routine use of cardiopulmonary bypass because time limitations were imposed by only hypothermia and no inflow occlusion.[127]

Bedford et al.[1] and Bjork et al.[2] described the presentation of this complication during or immediately after operation when hypothermia had been used. More commonly, there is an apparently uncomplicated immediate postoperative course with satisfactory, even dramatic, reduction in heart size, and pulmonary vascularity, only to be followed by the insidious onset of cyanosis, dyspnea with effort, and eventually finger clubbing and polycythemia.[35]

There also remains a risk of paradoxical embolism as in this case. The level of cyanosis may be reduced by factors such as partial diversion of the IVC to left atrium or stenosis of the IVC with decompressing collaterals draining to right atrium via the azygos and SVC.

In certain cases the cyanosis was discovered many years after closure of the ASD when the patients were being evaluated for some unrelated disorder.[8] Recent case reports of this complication have mostly been reported in adult patients where the ASD closure was done during childhood, that is, during the early era of cardiac surgery.[8-10]

Patients with this complication may be misdiagnosed as Eisenmenger's syndrome if one is not aware of this complication and if the patient is not thoroughly evaluated.[8] But with the advances in cardiac imaging and more awareness of this complication, these lesions can be discovered earlier. Traditionally, contrast echocardiogram with venous access in the lower limb and cardiac catheterization with IVC angiogram have been used to diagnose this complication.[6] Newer noninvasive imaging modalities like cardiac magnetic resonance (CMR) have been used successfully to accurately diagnose this condition.[8]

Transcatheter closure of the defects with device may be possible theoretically in cases where there is a residual defect in case of low lying secundum ASD with partial diversion of the IVC to the left atrium. The literature search though did not reveal any such reported case. In our case, the IVC was completely diverted to the left atrium with a small residual defect at the upper end of the patch. The only possible way of treating this defect by transcatheter means was to place a covered stent from the IVC into the LA and then into the right atrium via the fenestration. We decided against that in view of the young age of the child and uncertainty regarding placing a stent on the systemic side of the heart with a need for anticoagulation therapy.

Early diagnosis of this condition can avoid complications related to cyanosis and hypoxia as well as other potentially life threatening complications like stroke due to paradoxical embolism.