Subpulmonary pseudoaneurysm—a rare complication following surgical ventricular septal defect closure

Abstract

In this report, we describe the surgical management of a subpulmonary pseudoaneurysm following surgical closure of ventricular septal defect in an infant. Diagnosis, pathogenesis, and surgical considerations for management of this complication are discussed.

Introduction

Subpulmonary pseudoaneurysm (SP-PA) is a rare complication following surgical closure of ventricular septal defect (VSD). This report describes successful surgical management of this life-threatening complication.

Case report

A 2-month and 15-day-old male patient (weight 3.2 kg) presented to our clinic with history of recurrent respiratory tract infections, difficulty in feeding, excessive sweating while feeding, and failure to thrive. There was 4/5 grade pansystolic murmur in the left parasternal region on examination. On further evaluation, an electrocardiogram showed right axis deviation, biventricular hypertrophy, and left ventricular volume overload. Chest X-ray revealed cardiomegaly with pulmonary plethora. His echocardiogram showed a large doubly committed VSD with moderate juxta-ductal coarctation of the aorta with severe pulmonary arterial hypertension. He underwent single-stage VSD closure with 0.4-mm polytetrafluoroethylene (PTFE) patch through transpulmonary artery approach and coarctation repair by end-to-end anastomosis of the posterior wall with anterior wall augmentation with Contegra (bovine jugular vein graft) patch under moderate hypothermia. Cardiopulmonary bypass (CPB) was established with innominate artery cannulation using 3.5-mm PTFE graft and bicaval venous cannulation. Weaning from CPB was uneventful with milrinone and adrenaline. Postoperative echocardiography showed no residual VSD and well-flowing arch.

However, the postoperative course was stormy; he developed deep sternal wound infection, sepsis, and peritonitis. The sternum was rewired after the control of sepsis. Due to this, he had prolonged mechanical ventilation. Periodic echocardiograms were normal until then. Two months after the surgery, he developed hyperdynamic circulation, and his condition started deteriorating again. Chest X-ray showed signs of mediastinal widening and increased pulmonary vascularity (Fig. 1a). Echocardiogram showed VSD patch dehiscence (Fig. 1b) and a large pouch communicating with the pulmonary artery at the VSD level (Fig. 1c). A cardiac computed tomogram confirmed the finding of a large (40*35*35 mm-transverse*craniocaudal*anteroposterior) multiloculated contrast-filled structure originating from the base of the pulmonary artery and extending in the retrosternal space and another pouch extending posterior to it (Fig. 1d, e).

Fig. 1.

a Chest X-ray image showing widened mediastinal shadow and pulmonary plethora following VSD patch dehiscence and development of pseudoaneurysm. b 2-D-Echo image in parasternal short axis view at aortic valve level showing doubly committed VSD patch dehiscence (2-D-Echo, two-dimensional echocardiography; VSD, ventricular septal defect; PA, pulmonary artery; AA, ascending aorta). c 2-D contrast echocardiogram, long axis view image, showing large, multiloculated pseudoaneurysm communicating with pulmonary artery (2-D, two-dimensional). d Computed tomography image in sagittal section showing multiloculated pseudoaneurysm occupying retrosternal space. e 3-D-VRT image of the pseudoaneurysm (3-D-VRT, three-dimensional volume rendering technique)

As a large portion of the aneurysm was adherent to the posterior side of the sternum, and it was rewired sternum, we decided to do peripheral cannulation for the second surgery. We exposed the left external iliac artery and vein through an oblique left lower abdominal incision and used the extraperitoneal approach. We sutured a 3.5-mm PTFE graft to the left external iliac artery and inserted the arterial cannula in it. The left external iliac vein was cannulated directly and partial CPB was established (Fig. 2a). Median sternotomy was performed, and intrapericardial adhesions were released. The aneurysm was adherent to the undersurface of the sternum (Fig. 2b). We inserted an additional right atrial cannula to go on full CPB. We dissected the pseudoaneurysm and separated it from the aorta and pulmonary artery (Fig. 2c). We found a large 5 × 6 cm sized outpouching from the medial aspect of the pulmonary artery with a narrow neck coursing on the anterior aspect of the pulmonary artery. The heart was arrested with antegrade del Nido cardioplegia, and the pulmonary artery was opened transversely. The pseudoaneurysm was laid open. The mouth of the aneurysm was lying in the medial sub-commissural area between the posterior and right pulmonary valve cusps (Fig. 3a). There were another two openings just beneath the nadir of the destroyed posterior cusp, communicating with the pouch located on the posterior aspect of the pulmonary artery. The VSD patch suture had given away at its upper sub-arterial margin.

Fig. 2.

Intraoperative image showing a peripheral bypass established via left external Iliac artery and vein cannulation, b partially collapsed pseudoaneurysm adherent to undersurface of the sternum, and c large pseudoaneurysm dissected from surrounding tissue sitting on top of the heart

Fig. 3.

Intraoperative image showing a mouth of the pseudoaneurysm located just below the pulmonary valve commissure (yellow arrow—artery forceps inserted through the pseudoaneurysm opening just below the pulmonary valve); b posterior pulmonary valve cusp excised, VSD and mouth of pseudoaneurysm closed with new PTFE patch (VSD, ventricular septal defect; PTFE, polytetrafluoroethylene); and c plicated pseudoaneurysm wall remaining after excision of the pseudoaneurysm

We excised the destroyed pulmonary leaflet and closed the VSD with a new 0.4-mm PTFE patch incorporating the mouth of the SP-PA within the suture (Fig. 3b). The wall of the SP-PA near its mouth was preserved and plicated to close the pseudoaneurysm from outside (Fig. 3c). The residual SP-PA wall was excised and sent for culture and histopathology. The patient came off CPB smoothly, and the sternum was closed. The tissue sent for culture did not show any growth. Histopathology revealed leakage of blood vessels with surrounding fibrosis. Postoperative echocardiography showed no residual VSD, no aneurysmal pouch, and good biventricular function. Though the immediate postoperative course was stormy, the patient recovered well and was discharged from our hospital. At 3-month follow-up, the patient was asymptomatic and had gained weight. Echocardiogram showed no residual VSD, well-flowing arch, and good biventricular function.

Discussion

Surgical VSD closure is one of the most common pediatric cardiac surgeries performed, and with advances in cardiac surgery over the years, it has become a relatively safe procedure with overall mortality and major adverse event rate of 3–6% [1]. Nevertheless, complications do occur. Postoperative bleeding, transient and complete heart block, other cardiac rhythm disturbances, reintubation, difficult weaning from the ventilator, pulmonary complications (atelectasis, pleural effusion, bronchospasm, and pneumothorax), wound infection, sternal dehiscence, post pericardiotomy syndrome, chylothorax, renal failure, seizures, stroke, diaphragm palsy, severe ventricular dysfunction, valvar (aortic, tricuspid, or pulmonary) regurgitation, infective endocarditis, and re-operation for significant residual VSD are the known complications following surgical closure of VSD [2]. Other rare complications of surgical VSD closure include left ventricular pseudoaneurysm [3], interventricular septal hematoma [4], and aortic root pseudoaneurysm [5]. A subpulmonary pseudoaneurysm (SP-PA) is a very rare complication following the closure of a doubly committed VSD. It has not been described in the literature to the best of our knowledge.

A true aneurysm contains all the three layers of the ventricular wall—endocardium, myocardium, and pericardium. On the other hand, a pseudoaneurysm or false aneurysm wall is composed of only fibrous pericardial tissue. In children, right ventricular outflow tract pseudoaneurysms are reported following use of biological tissue for closure of infundibular incisions [6]. Peripheral pulmonary artery pseudoaneurysm can occur due to infective endocarditis, as a late sequel of residual VSD following surgical VSD closure [7]. Pseudoaneurysms arising from the left ventricle have been reported following purulent bacterial pericarditis, most commonly involving Staphylococcus aureus [8]. Though our patient did not have any positive mediastinal culture, he had sternal dehiscence in the early postoperative period. His blood culture and endotracheal tube cultures were positive for Pseudomonas aeruginosa and Klebsiella pneumoniae and were treated with appropriate antibiotics according to the sensitivity reports. Postoperative sepsis with mediastinal infection induces tissue inflammation. The fragility of tissue in the immediate postoperative period following surgical VSD closure is dangerous since VSD sutures can cut through this frangible tissue and lead to VSD patch dehiscence. Our patient had sepsis in the early postoperative period, which could have led to inflammation and dehiscence of the VSD patch, which exposed the weak area to systemic pressures and led to the formation of this huge SP-PA. The pseudoaneurysm further increased until it occupied the whole retrosternal region with multiple loculations.

Many studies have also shown low body weight (<6 kg) to be a predictor of morbidity following surgical VSD closure [9]. In contrast to them, many other studies have proven no association between major adverse events or complications following surgical VSD closure and body weight. However, all studies agree that low body weight is associated with longer postoperative ventilation time and more extended postoperative stay in the hospital [2]. Our patient’s low body weight was a significant risk factor for prolonged recovery and susceptibility to sepsis.

Another interesting observation was that our patient was hemodynamically stable in the immediate and late postoperative periods of sepsis. His chest X-ray did not show any plethora or signs of increased pulmonary blood flow despite the dehiscence of the VSD patch. The pseudoaneurysm probably contained a significant portion of the left to right shunt. Only after the pseudoaneurysm occupied a major portion of the retrosternal space, did the patient’s symptoms become clinically evident.

Pseudoaneurysms are life-threatening and spontaneous rupture can lead to sudden death. Hence, repair at the earliest should be the thumb rule in all cases. However, we need to assess the risk of immediate surgery against odds of fulminant infection and surgical misadventures. Strategic surgical planning is essential to prevent mishaps that lead to on-table death. So, first, we repeated all cultures and confirmed them to be negative before taking the patient up for redo surgery. We also studied the echocardiogram and computed tomography images to confirm the exact location and extent of the pseudoaneurysm. Our patient was a tiny 3-kg baby with a previously infected midline sternotomy and a large retrosternal pseudoaneurysm. The size of the femoral vessels of the child was too small to establish complication-free peripheral bypass. Hence, we established peripheral bypass through the left external iliac artery and vein (the central line was in situ on the right side). The peripheral bypass provided only 40% of the required flow. However, it made redo sternotomy safer. The pseudoaneurysm partially collapsed on bypass which made sternotomy and dissection of the pseudoaneurysm uneventful. Once we dissected the right atrium, an additional venous cannula in the right atrium helped us to go on full CPB. The mouth of the SP-PA was closed from inside during VSD closure using interrupted pledgetted sutures. The pseudoaneurysm was completely excised except for a small margin near its mouth externally. This margin was used to close the mouth of the pseudoaneurysm from the outside. In this manner, the closure of the SP-PA mouth was doubly reinforced to ensure that it did not recur. A safe surgical plan made this high-risk operation successful.

Conclusion

Infection and intrinsic weakness of the tissue can lead to development of SP-PA following surgical closure of a doubly committed VSD. Surgical correction, though high risk, can have a favorable outcome in this complication and should be attempted given the grave consequences of conservative management.

Funding

None.

Declarations

Ethics approval

This article does not contain any studies with human participants or animals performed by any of the authors. Institutional Ethics Committee approval was not required for this case report.

Consent for publication

Written informed consent was obtained from parents of the patient for publication of this case report and accompanying images.

Conflict of interest

The authors declare that they have no conflict of interest.