Adult Presentation of Subaortic Stenosis: Another Great Hypertrophic Cardiomyopathy Mimic

Now You See Me Now You Don't: Subaortic Membrane Causing a Diagnostic Dilemma

Subaortic stenosis secondary to subaortic membrane is the second most common form of left ventricular outflow tract obstruction. We present the case of a 70-year-old male patient who presented with a 6-week history of progressive signs of heart failure. Multimodality imaging was required to confirm the presence of a subaortic membrane. (Level of Difficulty: Beginner.).

Significance of aortoseptal angle anomalies to left ventricular hemodynamics and subaortic stenosis: A numerical study

PURPOSE

Discrete subaortic stenosis (DSS) is an obstructive cardiac disease caused by a membranous lesion in the left ventricular (LV) outflow tract (LVOT). Although its etiology is unknown, the higher prevalence of DSS in LVOT anatomies featuring a steep aortoseptal angle (AoSA) suggests a potential role for hemodynamics. Therefore, the objective of this study was to quantify the impact of AoSA steepening on the LV three-dimensional (3D) hemodynamic stress environment.

METHODS

A 3D LV model reconstructed from cardiac cine-magnetic resonance imaging was connected to four LVOT geometrical variations spanning the clinical AoSA range (115°-160°). LV hemodynamic stresses were characterized in terms of cycle-averaged pressure, temporal shear magnitude (TSM), and oscillatory shear index. The wall shear stress (WSS) topological skeleton was further analyzed by computing the scaled divergence of the WSS vector field.

RESULTS

AoSA steepening caused an increasingly perturbed subaortic flow marked by LVOT flow skewness and complex 3D secondary flow patterns. These disturbances generated WSS overloads (>45% increase in TSM vs. 160° model) on the inferior LVOT wall, and increased WSS contraction (>66% decrease in WSS divergence vs. 160° model) in regions prone to DSS membrane formation.

CONCLUSIONS

AoSA steepening generated substantial hemodynamic stress abnormalities in LVOT regions prone to DSS formation. Further studies are needed to assess the possible impact of such mechanical abnormalities on the tissue and cellular responses.

Adult Presentation of Subaortic Stenosis with Subaortic Membrane Treated with Surgical Removal

Subaortic stenosis (SAS) is a rare heart disease in adults with an unclear etiology and variable clinical presentation. In some cases, SAS appears as hypertrophic cardiomyopathy with obstruction due to the accompanying systolic anterior motion of the mitral valve. A 46-year-old male with dizziness for several months presented in the outpatient department. Two-dimensional transthoracic echocardiography demonstrated a slightly hypertrophic left ventricle with normal systolic function without wall-motion abnormalities. Just below the aortic valve, a linear structure protruding from the septum side and the left-ventricular outflow tract (LVOT) side of the mitral valve was confirmed, which was causing a significant pressure gradient (mean and maximum of 91 mmHg and 138 mmHg, respectively). A diagnosis of SAS with subaortic membrane was made, and surgical myomectomy and subaortic membrane removal surgery were performed. Postoperative transthoracic echocardiography did not show flow acceleration through the LVOT, nor a significant pressure gradient across the aortic valve. This case report highlights the clinical significance of SAS with subaortic membrane, which can be confused with aortic stenosis of other etiology.

Adult Presentation of Subaortic Stenosis with Subaortic Membrane Treated with Surgical Removal

Subaortic stenosis (SAS) is a rare heart disease in adults with an unclear etiology and variable clinical presentation. In some cases, SAS appears as hypertrophic cardiomyopathy with obstruction due to the accompanying systolic anterior motion of the mitral valve. A 46-year-old male with dizziness for several months presented in the outpatient department. Two-dimensional transthoracic echocardiography demonstrated a slightly hypertrophic left ventricle with normal systolic function without wall-motion abnormalities. Just below the aortic valve, a linear structure protruding from the septum side and the left-ventricular outflow tract (LVOT) side of the mitral valve was confirmed, which was causing a significant pressure gradient (mean and maximum of 91 mmHg and 138 mmHg, respectively). A diagnosis of SAS with subaortic membrane was made, and surgical myomectomy and subaortic membrane removal surgery were performed. Postoperative transthoracic echocardiography did not show flow acceleration through the LVOT, nor a significant pressure gradient across the aortic valve. This case report highlights the clinical significance of SAS with subaortic membrane, which can be confused with aortic stenosis of other etiology.

Echocardiographic assessment in cardiogenic shock

Echocardiography is the most helpful diagnostic modality in cardiogenic shock, the management of which still remains challenging despite advances in therapeutic options. The presence of cardiogenic shock portends high mortality rates. Therefore, rapid recognition, identification of the underlying cause, and evaluation of the severity of hemodynamic dysfunction are vital for correct management. Whether the cause of shock is unknown, suspected, or established, echocardiography is utilized in its diagnosis and management as well as to monitor progress. It is recommended as the modality of first choice. No other investigative bedside tool can offer comparable diagnostic capability, allowing for exact targeting of the underlying cardiac and hemodynamic problems. Echocardiography can promptly provide an impression of the etiology of shock and the potential line of treatment. Normal left ventricular and right ventricular systolic function, normal cardiac chamber dimensions, absence of any significant valvular pathology, and absence of any pericardial effusion virtually rule out a cardiac cause of shock. This review discusses the role of echocardiography as a decision-making tool in the evaluation and management of cardiogenic shock.

Subvalvular aortic stenosis: a review of current literature

Subvalvular aortic stenosis (SAS) is one of the common adult congenital heart diseases, with a prevalence of 6.5%. It is usually diagnosed in the first decade of life. Echocardiography is the test of choice to diagnose SAS. Surgical correction is the best treatment modality, and the prognosis is usually excellent. In this review, we describe the pathophysiology, diagnosis, prognosis, and management of SAS with a focus on different pathophysiologic mechanisms, diagnostic approach, and prognosis of the disease by reviewing the current literature.

Bands, Chords, Tendons, and Membranes in the Heart: An Imaging Overview

Crests, bands, chords, and membranes can be seen within the different cardiac chambers, with variable clinical significance. They can be incidental or can have clinical implications by causing hemodynamic disturbance. It is crucial to know the morphology and orientation of normal structures, aberrant or accessory muscles, and abnormal membranes to diagnose the hemodynamic disturbance associated with them. Newer generation computed tomographic scanners and faster magnetic resonance imaging sequences offer high spatial and temporal resolution allowing for acquisition of high resolution images of the cardiac chambers improving identification of small internal structures, such as papillary muscles, muscular bands, chords, and membranes. They also help in identification of other associated complications, malformations, and provide a road map for treatment. In this article, we review cross-sectional cardiac imaging findings of normal anatomical variants and distinctive imaging features of pathologic bands, chords, or membranes, which may produce significant hemodynamic changes and clinical symptomatology.