A Membranous Septal Aneurysm Causing Right Ventricular Outflow Tract Obstruction in an Adult

Rare Incidental Finding of an Interventricular Membranous Septal Aneurysm in an Adult Presenting for Aortic Valve Replacement

Interventricular membranous septal aneurysm (IVMSA) is a rare cardiac anomaly that typically coexists with other cardiac malformations. Recognition of IVMSAs is important for risk mitigation of potentially serious complications such as right ventricular outflow obstruction and proper characterization of the lesion is critical for planning of surgical repair. Literature reports of this condition are sparse and appear limited to case reports. Bicuspid aortic valve (BAV) is a common congenital cardiac malformation tending to present later in life with symptomatic stenosis and is frequently associated with other defects. We report an unusual case of an elderly woman with a BAV undergoing aortic valve replacement who was incidentally diagnosed with an IVMSA. This case report describes intraoperative transesophageal echocardiogram (TEE) characterization of the IVMSA used to help plan the surgical procedure. TEE accurately visualized the IVMSA's exact anatomic location and impact on cardiac function which led to the decision to surgically repair the IVMSA with an autologous patch. This report also includes a comparative discussion of clinical presentations, diagnostic approaches, and management strategies in previously published IVMSA case reports and considerations for operative management.

Right Ventricular Outflow Tract Obstruction by an Aneurysm of the Ventricular Membranous Septum: A Systematic Review of Case Reports

We performed a literature search to identify the details of patients with right ventricular outflow tract obstruction caused by an aneurysm of the ventricular membranous septum in a perimembranous ventricular septal defect. Thirty-one cases with a median age of 29 years (range, 1-69 years) were studied. A right ventricle-pulmonary artery systolic pressure gradient ranged from 35 to 107 mm Hg (mean 69 mm Hg). An interventricular shunt was absent in eight patients: two children and six adults. It is necessary to monitor the size of an aneurysm of the ventricular membranous septum, whether or not an interventricular shunt is present.

Right Ventricular Outflow Tract Obstruction in Adults: A Systematic Review and Meta-analysis

Background

Right ventricular outflow tract obstruction (RVOTO) is a cause of hemodynamic instability that can occur in several situations, including cardiac surgery, lung transplantation, and thoracic surgery, and in critically ill patients. The timely diagnosis of RVOTO is important because it requires specific considerations, including the adverse effects of positive inotropes, and depending on the etiology, the requirement for urgent surgical intervention.

Methods

The objective of this systematic review and meta-analysis was to determine the prevalence of RVOTO in adult patients, and the distribution of all reported cases by etiology.

Results

Of 233 available reports, there were 229 case reports or series, and 4 retrospective cohort studies, with one study also reporting a prospective cohort. Of 291 reported cases of RVOTO, 61 (21%) were congenital, 56 (19%) were iatrogenic, and 174 (60%) were neither congenital nor iatrogenic (including intracardiac tumour). The mechanism of RVOTO was an intrinsic obstruction in 169 cases (58%), and an extrinsic obstruction in 122 cases (42%). A mechanical obstruction causing RVOTO was present in 262 cases (90%), and 29 cases of dynamic RVOTO (10%) were reported. In the 5 included cohorts, with a total of 1122 patients, the overall prevalence was estimated to be 4.0% (1%-9%).

Conclusions

RVOTO, though rare, remains clinically important, and therefore, multicentre studies are warranted to better understand the prevalence, causes, and consequences of RVOTO.

An interventricular membranous septal aneurysm obstructing the right ventricle outflow tract in a five-year-old boy: a case report

Background

While the aneurysms of the membranous septum (AVS) are rare, the possibility that they lead to obstruction is even rarer. To the best of our knowledge, 11 similar cases have been reported since 1982.

Case presentation

Initially, the five-year-old boy was evaluated for dyspnoea that had been present since birth. He did not receive any medical treatment until the previous year. At the age of four, the transthoracic echocardiography showed a large aneurysm extending to the right ventricular outflow tract (RVOT) and causing RVOT stenosis. Complete surgical resection of the aneurysmal tissue was performed, and the boy was discharged home in satisfactory condition.

Conclusions

As the occurrence of RVOT obstruction by a membranous ventricular septal aneurysm is very rare, we are reporting the second case in which an aneurysm of the membranous septum dynamically obstructed the RVOT in a child. We are also reviewing all the previously reported similar cases in the literature. Further studies are needed to obtain a more comprehensive understanding of aneurysms of the membranous septum (AVS).

Spontaneous Closure of Perimembranous Ventricular Septal Defects: A Janus-Faced Condition

•Large perimembranous VSDs can occasionally close spontaneously by a septal aneurysm. •Complications of aneurysmatic VSD closure include RVOT obstruction. •The use of multimodal imaging allows accurate diagnosis of RVOT obstruction. •RVOT obstruction due to septal aneurysm is preferably treated by surgical excision. •Patients with aneurysmatic closure of perimembranous VSD need life-long observation.