Unmasking the culprit: MAPCA masquerading as RV failure in post surgical correction of TOF

Abstract

Pulmonary regurgitation and right ventricular dilatation are major determinants of long-term follow up of surgically corrected tetralogy of Fallot. Occasionally, there are undiagnosed associated anomalies, which can exaggerate pulmonary regurgitation. The present report describes long-term effect of major aorto pulmonary collateral on right ventricular volume also a result of successful intervention.

<Learning objective: Following pulmonary valvotomy in conotruncal anomalies there is development of significant pulmonary regurgitation. On long-term follow up, they are candidates for pulmonary valve replacement. A thorough search and management of associated defects (such as major aorto pulmonary collaterals, peripheral pulmonary stenosis) can reverse right ventricular dilatation and postpone pulmonary valve placement.>

Introduction

Following surgical correction of congenital heart disease, undiagnosed defects can present in a variety of ways. It is important to detect and rectify them as soon as diagnosed. We wish to discuss a patient with significant right ventricular (RV) dilatation in long-term follow up of surgical correction of tetralogy of Fallot. There was improvement of RV volumes after closure of undiagnosed major aorto pulmonary collaterals (MAPCA). There is also discussion about hemodynamic consideration and causation.

Case report

A 32-year-old woman had undergone surgical correction of tetralogy of Fallot with transannular patch at the age of 8 years. The operative details were suggestive of increased venous return during surgery. The post operative recovery was uneventful. Following which she had 2 uneventful deliveries (last 8 years previously). She was symptomatic for the previous 6 months and complaining of easy fatigability. On clinical examination there was ejection systolic and early diastolic murmur in pulmonary area. Her echocardiography was s/o dilated right atrium and right ventricle. There was severe pulmonary regurgitation (PR) but no RV outflow acceleration. Pulmonary artery and branches were dilated and confluent. There was no mitral or tricuspid regurgitation. Left ventricular systolic function was 56%. Rhythm was sinus and QRS duration was 150 ms.

Cardiac magnetic resonance (CMR) findings were (1) end diastolic and end systolic RV volumes 170 ml/m² and 90 ml/m², respectively, left ventricular volumes were 92 ml/m² and 38 ml/m², respectively. (2) RV ejection fraction and left ventricular ejection fraction 44% and 59%, respectively. There was significant dilatation of RV outflow track (4.5 cm) and PR fraction was 53%. There was a MAPCA arising from descending aorta and supplying right lung.

After valid informed consent, the patient underwent catheterization. RV pressure was 41/8 mmHg. Pulmonary artery pressure was 39/12 mmHg. There was free PR. The pulmonary artery and branches were confluent without any evidence of obstruction. Left ventricular pressure was 128/9 mmHg and aortic 127/76 mmHg. There were 3 MAPCA from aorta. Pulmonary segments supplied with MAPCA had dual blood supply. It was documented with MAPCA and native pulmonary artery angiograms in various projections. These MAPCA were communicating with branch pulmonary arteries.

• (1)The largest was arising from descending aorta at D4 level and supplying right lung. There was distal narrowing. It was feeding right pulmonary artery and branches. It was closed with 16 mm Cera vascular plug (Lifetech scientific, Shenzhen, China) (Fig. 1, Fig. 2).
• (2)MAPCA 2: From right renal artery: It was a 4-mm vessel supplying right lung. It was occluded with multiple coils (Cook Medical, Bloomington, IN, USA).
• (3)MAPCA 3: From descending thoracic aorta at D5 level. It was occluded with multiple coils.

Fig. 1.

Baseline descending aortogram: Large major aorto pulmonary collaterals from aorta and supplying right lung.

Fig. 2.

Vascular plug closure of major aorto pulmonary collaterals.

The patient had an uneventful recovery after the procedure. There was improvement in her symptoms. CMR was repeated after 9 months. There was improvement in RV volumes (end systolic 127 ml/m², end diastolic 70 ml/m², RV ejection fraction 45%, PR fraction 45%). There was also improvement in left ventricular volumes (end diastolic 81 ml/m² and end systolic 30 ml/m², left ventricular ejection fraction 63%).

Discussion

MAPCA are not frequent in the setting of tetralogy of Fallot with pulmonary stenosis [1]. They behave very much like patent ductus arteriosus (PDA). If unnoticed, they can cause significant (1) significant venous return during surgical correction of tetralogy of Fallot on heart lung machine, (2) low cardiac output during recovery. It seems likely that MAPCA will lead to left-sided volume overload, although it was not observed in this case. Unlike PDA, this patient had significant RV volume overload. In presence of free PR, competitive flow between MAPCA and forward RV output might have led to worsening of PR and earlier than expected RV dilatation. In the present case, baseline RV volumes were high enough to justify pulmonary valve implantation. However, following the intervention there was significant reduction in RV volumes at midterm follow up and valve placement could be postponed.

Conflict of interest

There are no conflicts of interest.

Funding

None.