Multimodality imaging in a child with complete atrioventricular canal defect, left superior vena cava, and airway compression: Echocardiography, bronchoscopy, and lung ultrasound insights

Abstract

Congenital heart disease may coexist with airway abnormalities, increasing perioperative risk. We report a 2-year-old girl with a complete atrioventricular canal defect (CAVCD), left superior vena cava (LSVC), and severe pulmonary hypertension, in whom multimodality imaging was pivotal for diagnosis and management. Transthoracic echocardiography confirmed CAVCD, LSVC, and severe pulmonary hypertension. Preoperative computed tomography demonstrated left pulmonary artery compression of the left main bronchus and a suspected cor triatriatum. Intraoperative bronchoscopy revealed left bronchomalacia, while transesophageal echocardiography identified a dilated coronary sinus as the cause of left atrial inflow turbulence, excluding cor triatriatum. Surgical management included CAVCD repair and LSVC anastomosis to the right atrial appendage. Post–cardiopulmonary bypass echocardiography showed no residual atrioventricular valve regurgitation or inflow gradient. Lung ultrasound prior to extubation excluded left lung collapse. This case highlights the role of multimodality imaging in guiding diagnosis, surgical planning, and safe perioperative management.

INTRODUCTION

Complete atrioventricular canal defect (CAVCD) is a well-recognized congenital cardiac anomaly and is frequently associated with a left superior vena cava (LSVC). Rarely, turbulence of left atrial inflow on echocardiography may mimic cor triatriatum, complicating preoperative diagnosis. In addition, children with congenital heart disease may have associated airway abnormalities such as bronchomalacia or extrinsic airway compression, which can significantly influence perioperative management. We report a case in which multimodality imaging provided diagnostic clarity and guided surgical and perioperative decision-making, highlighting the complementary roles of cardiac and airway imaging.

CASE REPORT

A 2 -year-old female child (height: 76 cm and weight: 7.5 kg) was referred with tachypnea, feeding difficulty, and poor weight gain. On examination, heart rate was 150–160/min, with a SpO₂ of 93% on room air. Cardiac auscultation revealed a loud P2, an ejection systolic murmur at the left upper sternal border, and a pansystolic murmur at the apex.

Transthoracic echocardiography revealed a CAVCD (Rastelli’s type A) with mild-to-moderate left atrioventricular valve regurgitation and no significant right-sided regurgitation. A large ostium primum atrial septal defect and a large inlet ventricular septal defect with left-to-right shunt were present. The left ventricular outflow tract appeared elongated. Bilateral superior vena cavae were identified, with the LSVC draining into the coronary sinus. A shelf-like projection in the left atrium caused a mean transmitral gradient of 12 mmHg; however, the lumen appeared to align more with the coronary sinus than with true cor triatriatum. Severe hyperkinetic pulmonary arterial hypertension was also documented.

Preoperative computed tomography (CT) angiography performed at the referring hospital, indicated for localized wheeze and to clarify ambiguous left atrial morphology on echocardiography, demonstrated a balanced CAVCD with a shelf-like infolding mimicking cor triatriatum [Figure 1]. The scan also revealed extrinsic compression of the left main bronchus between the left pulmonary artery (LPA) and the descending thoracic aorta [Figure 2a and b], explaining the clinical wheeze.

Figure 1.

Arrowhead toward the shelf-like projection into the left atrium due to cor triatriatum. LAA: Left atrial appendage, RA: Right atrium, LA: Left atrium, RV: Right ventricle, LV: Left ventricle

Figure 2.

(a and b) Arrowhead toward left bronchial narrowing caused by dilated left pulmonary artery. LPA: Left pulmonary artery

The pulmonary hypertension had both pre- and postcapillary components. As pulmonary venous hypertension can paradoxically protect against the progression of pulmonary arterial hypertension, and the cardiac catheterization was unlikely to provide additional discriminatory information, the multidisciplinary team elected to proceed with definitive repair after clinical optimization. The ventricles were balanced (right: 4.3 cm² and left: 4 cm²) and contractile, indicating operability despite the patient’s young age.

Based on preoperative imaging, the planned procedure included atrioventricular canal repair, excision of the presumed cor triatriatum membrane, an LSVC-to-right SVC anastomosis, and LPA-plasty, with possible left bronchial pexy depending on intraoperative findings.

After confirmation of fasting status, anesthesia induction was uneventful. Intraoperative bronchoscopy in the spontaneously breathing child demonstrated 50%–70% narrowing at the site of LPA compression with dynamic airway collapse consistent with left bronchomalacia [Video 1]. The airway was subsequently secured. As per institutional protocol, intraoperative bronchoscopy is performed in cases with airway compression on CT to assess dynamic collapse and guide surgical airway intervention. In this patient, bronchoscopy confirmed moderate left bronchomalacia without distal collapse, and bronchopexy was not required.

Vascular access was obtained through the femoral route under ultrasound guidance, avoiding the neck because of the planned LSVC rerouting.

Before cardiopulmonary bypass, transesophageal echocardiography (TEE) confirmed a balanced CAVCD with moderate left atrioventricular valve regurgitation. A markedly dilated coronary sinus secondary to LSVC drainage was identified as the cause of left atrial inflow turbulence, thereby excluding cor triatriatum [Video 2]. Interventricular septal flattening during systole with a dilated main pulmonary artery was also noted. No turbulence was observed across either ventricular outflow tract. The elevated transmitral gradient was considered partly flow-related due to tachycardia and a large left-to-right shunt. The surgical team therefore elected to reroute the LSVC to decompress the coronary sinus and restore normal left atrial geometry.

Surgery consisted of complete CAVCD repair with rerouting of the LSVC to the right atrial appendage. The LSVC was disconnected from the coronary sinus behind the left atrium, and the coronary sinus was unroofed. A modified single-patch technique was used to close both septal defects. The left atrioventricular valve cleft was closed with interrupted sutures, and the right atrioventricular valve was repaired with partial annuloplasty along the anterior tricuspid leaflet. The LSVC was then anastomosed to the right atrial appendage.

Prior to weaning from bypass, a milrinone bolus (1 mcg/kg) was administered, with nitric oxide kept on standby. The patient was successfully weaned on milrinone (0.7 mcg/kg/min) and adrenaline (0.05 mcg/kg/min).

Postbypass TEE demonstrated intact atrial and ventricular septal patches with only trace left atrioventricular valve regurgitation. Left atrial inflow turbulence had resolved, and the left ventricle appeared spherical with normalization of septal geometry.

Before extubation, lung ultrasound (LUS) excluded left lung collapse and confirmed adequate bilateral aeration. Serial LUS examinations were performed during spontaneous breathing to monitor for recurrent collapse. The child was extubated uneventfully in the intensive care unit approximately 6 h postoperatively, and recovery remained stable. At the 3-month follow-up, there was no recurrence of wheeze or respiratory infection.

CASE DISCUSSION

Although echocardiography is routinely used in pediatric cardiac surgery, this case underscores the value of cross-modality interpretation when preoperative findings are incongruent. In our patient, the apparent cor triatriatum on CT was clarified as a dilated coronary sinus on intraoperative TEE, directly influencing surgical strategy and avoiding unnecessary surgical modification.[1]

Several conditions may mimic the shelf-like appearance of cor triatriatum. Marked dilation of the coronary sinus due to persistent LSVC can cause left atrial or mitral inflow obstruction and is an important differential diagnosis.[2] Supramitral rings produce obstruction closer to the mitral annulus and may be difficult to distinguish on transthoracic imaging.

In our patient, the transmitral gradient was exacerbated by tachycardia and increased left-to-right shunt. Intraoperative imaging demonstrated posterior compression of the left atrium by a dilated coronary sinus, resulting in functional inflow turbulence. Rerouting the LSVC relieved this compression, abolished the pseudogradient, and prevented future inflow distortion. Similar cases of functional inflow obstruction due to coronary sinus dilation have been reported and successfully managed with LSVC rerouting or coronary sinus unroofing.[2,3]

Embryologically, persistence of the left anterior cardinal vein and left horn of the sinus venosus gives rise to the LSVC draining into the coronary sinus. Subsequent coronary sinus dilation may create a posterior impression on the left atrial wall, mimicking an intracavitary membrane on two-dimensional imaging. Understanding this developmental relationship aids differentiation of true cor triatriatum from pseudomembranous appearances.[4] Other mimickers include unroofed coronary sinus, anomalous pulmonary venous connections, vertical veins, and a markedly dilated coronary sinus, as seen in our patient [Figure 3]. Definitive management is therefore directed at correcting anomalous venous drainage rather than intervening on the inflow region itself.[3]

Figure 3.

Mimickers of left atrial inflow turbulence. (a) Cor triatriatum sinister – intra-atrial membrane above the left atrial appendage, dividing pulmonary venous inflow. (b) Supramitral ring – membrane close to the mitral annulus. (c) Dilated left superior vena cava – vertical vascular structure simulating a membrane and turbulent inflow. (d) Unroofed coronary sinus – abnormal communication with the left atrium. (e) Partial anomalous pulmonary venous connection (vertical vein draining into atrium). LSVC: Left superior vena cava, PAPVC: Partial anomalous pulmonary venous connection

Extrinsic compression of the left main bronchus by the LPA was demonstrated on CT, while bronchoscopy confirmed associated bronchomalacia and allowed assessment of severity. The 50%–75% narrowing did not warrant bronchopexy. Identification of airway pathology is important, as it predisposes to periextubation complications and informs proactive airway management. Although bronchomalacia may improve after relief of extrinsic compression, long-term persistence is possible and warrants follow-up. In our patient, no residual symptoms were noted at 3 months. LUS, prior to extubation, excluded left lung collapse, a recognized risk in bronchomalacia, and facilitated safe fast-tracking, highlighting its expanding role in pediatric cardiac intensive care.

In our institution, multimodality imaging is selectively employed based on diagnostic complexity. While echocardiography usually suffices for surgical planning, adjunctive modalities such as CT, intraoperative TEE, bronchoscopy, and LUS are valuable when findings are discordant, extracardiac compression is suspected, or intraoperative clarification may alter management. This focused approach maximizes benefit while avoiding unnecessary risk.

CONCLUSIONS

In children with complex congenital heart disease, multimodality imaging – including CT, transthoracic echocardiography (TTE), TEE, bronchoscopy, and LUS – provides critical diagnostic precision and guides perioperative decision-making. This case demonstrates how integrating complementary imaging modalities optimizes surgical outcomes, enhances airway safety, and supports postoperative intensive care management.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.