Subaortic Membrane Resection in a 71-Year-Old Woman With Severe Left Ventricular Outflow Tract Obstruction
Poster #: 067
Session/Time: B
Author:
Ida Marie Sampson, BA
Mentor:
Matthew Summers, MD
Research Type: Case Report
Abstract
INTRODUCTION:
Subvalvular aortic stenosis (SAS), also known as subaortic stenosis, is a rare, gradually progressive congenital heart defect that causes fixed obstruction to blood flow across the left ventricular outflow tract (LVOT). This case report examines the clinical course of a 71-year-old woman diagnosed with a subaortic membrane causing severe LVOT stenosis, which was treated with surgical resection of the subaortic membrane.
CASE INFORMATION:
The patient is a 71-year-old female with a history of hypertension, type 2 diabetes mellitus, and chronic kidney disease with renal artery stenosis, presenting with exertional dyspnea, shortness of breath, and exercise intolerance. Additional history includes pulmonary hypertension, neuropathy, and occasional paroxysmal supraventricular tachycardia (pSVT) without sustained arrhythmia. Initial transthoracic echocardiography (TTE) revealed a hyperdynamic LV ejection fraction (EF) of 72% using Simpson's biplane. Further transesophageal echocardiography (TEE) narrowed down the diagnosis to a severe LVOT stenosis secondary to a subaortic membrane. Surgical resection of the subaortic membrane was performed successfully. Post-bypass TEE displayed good biventricular function with a decrease in the LVOT gradient from 55 mmHg pre-op to 18 mmHg post-op, and EF decreased from 72% to 60%. The patient experienced expected post-operative complications of hypotension, narcotic-induced hypoventilation, and stress-induced hyperglycemia, which were managed with temporary pressors, weaning to room air, and temporary IV insulin, respectively. The patient was discharged 6 days post-op to follow up in the clinic and complete a 14-day course of amiodarone.
DISCUSSION/CLINICAL FINDINGS:
This case highlights the unique presentation of a subaortic membrane in an elderly patient, providing an opportunity to explore the role of imaging in diagnosis as well as review effectiveness of currently adopted treatment protocols in the setting of multiple comorbidities. A transesophageal echocardiogram (TEE) played a pivotal role in differentiating between hypertrophic cardiomyopathy and LVOT obstruction due to a subaortic membrane. Current literature supports the use of transthoracic echocardiogram (TTE) as a standard for diagnosis, therefore utilization of additional TEE in the patient's diagnosis is noteworthy. The patient's advanced age and comorbidities necessitated careful surgical consideration due to increased perioperative risks. The observed post-operative reduction in ejection fraction and LVOT gradient, reflective of a positive outcome, broadens the understanding of treatment efficacy for subaortic membranes beyond younger adult populations that dominate current literature.
CONCLUSION:
Overall, subaortic membrane resection in the setting of advanced age and additional comorbidities can still produce favorable outcomes. Additionally, utilization of TEE as a complementary imaging modality in the management of subaortic stenosis proves advantageous.
Subvalvular aortic stenosis (SAS), also known as subaortic stenosis, is a rare, gradually progressive congenital heart defect that causes fixed obstruction to blood flow across the left ventricular outflow tract (LVOT). This case report examines the clinical course of a 71-year-old woman diagnosed with a subaortic membrane causing severe LVOT stenosis, which was treated with surgical resection of the subaortic membrane.
CASE INFORMATION:
The patient is a 71-year-old female with a history of hypertension, type 2 diabetes mellitus, and chronic kidney disease with renal artery stenosis, presenting with exertional dyspnea, shortness of breath, and exercise intolerance. Additional history includes pulmonary hypertension, neuropathy, and occasional paroxysmal supraventricular tachycardia (pSVT) without sustained arrhythmia. Initial transthoracic echocardiography (TTE) revealed a hyperdynamic LV ejection fraction (EF) of 72% using Simpson's biplane. Further transesophageal echocardiography (TEE) narrowed down the diagnosis to a severe LVOT stenosis secondary to a subaortic membrane. Surgical resection of the subaortic membrane was performed successfully. Post-bypass TEE displayed good biventricular function with a decrease in the LVOT gradient from 55 mmHg pre-op to 18 mmHg post-op, and EF decreased from 72% to 60%. The patient experienced expected post-operative complications of hypotension, narcotic-induced hypoventilation, and stress-induced hyperglycemia, which were managed with temporary pressors, weaning to room air, and temporary IV insulin, respectively. The patient was discharged 6 days post-op to follow up in the clinic and complete a 14-day course of amiodarone.
DISCUSSION/CLINICAL FINDINGS:
This case highlights the unique presentation of a subaortic membrane in an elderly patient, providing an opportunity to explore the role of imaging in diagnosis as well as review effectiveness of currently adopted treatment protocols in the setting of multiple comorbidities. A transesophageal echocardiogram (TEE) played a pivotal role in differentiating between hypertrophic cardiomyopathy and LVOT obstruction due to a subaortic membrane. Current literature supports the use of transthoracic echocardiogram (TTE) as a standard for diagnosis, therefore utilization of additional TEE in the patient's diagnosis is noteworthy. The patient's advanced age and comorbidities necessitated careful surgical consideration due to increased perioperative risks. The observed post-operative reduction in ejection fraction and LVOT gradient, reflective of a positive outcome, broadens the understanding of treatment efficacy for subaortic membranes beyond younger adult populations that dominate current literature.
CONCLUSION:
Overall, subaortic membrane resection in the setting of advanced age and additional comorbidities can still produce favorable outcomes. Additionally, utilization of TEE as a complementary imaging modality in the management of subaortic stenosis proves advantageous.