Analysis of 3-dimensional interventricular septum and abnormal muscle bundles models for septal myectomy

Adult Onset Hypertrophic Cardiomyopathy (HCM) Not Detected by Echocardiogram: A Case Presentation

Hypertrophic cardiomyopathy (HCM) is a genetic myocardial disease of the sarcomere protein. The age of diagnosis of HCM tends to be between the second to third decades of life. However, the recent occurrence of HCM in the fifth and sixth decades of life has been seen in an increasing number of cases. In all cases, a transthoracic echocardiogram (TTE) is considered the gold standard of imaging. Here, we present a case of a 54-year-old Caucasian male who presented to the emergency department (ED) with dyspnea while on vacation. An electrocardiogram (ECG) taken at the time did not suggest any abnormalities. After returning home, a stress test conducted indicated left anterior descending (LAD) artery stenosis. Following treatment, symptoms improved temporarily but eventually came back. Repeat ECGs and TTEs done over the next two years indicated grade II diastolic dysfunction and mild left ventricular hypertrophy, which led to changes in the medication regime. Nevertheless, his condition progressively deteriorated over time. Repeat appearances to the ED led to the utilization of magnetic resonance imaging (MRI) to assess cardiac morphology function and velocity flow. The results were consistent with HCM. This case presents a unique obstacle for the diagnosis of adult-onset HCM. The change made to his medication regimen seemingly aggravated the patients' condition. This case highlights the need for further imaging, beyond the gold standard, in adult males with repeated complaints of dyspnea on exertion (DOE).

Preoperative planning for transaortic septal myectomy using cardiac computed tomography in patients with subaortic septal hypertrophy associated with aortic stenosis: case series

Background

Electrocardiogram-gated cardiac computed tomography (CT) imaging enables a more accurate understanding of the patient's cardiac anatomy. Preoperative planning for transaortic septal myectomy (TASM), based on cardiac CT, may be useful in patients with subaortic septal hypertrophy associated with severe aortic stenosis (AS).

Case summary

Two elderly patients (age >80 years) with subaortic septal hypertrophy associated with AS underwent surgical aortic valve replacement (SAVR) and concomitant TASM after preoperative planning based on cardiac CT. Both patients showed subaortic septal hypertrophy with blood flow acceleration, left ventricular (LV) hypercontractility, and a short distance from the coaptation point of the mitral valve to the septum, resulting in possible dynamic LV outflow tract (LVOT) obstruction after resolution of AS. Optimal mid-diastolic images, selected from the 70-80% phase, were used for preoperative TASM planning. Planned sizes for myectomy based on multi-planar reconstruction were 10 × 26 × 9 mm (width × length × depth) and 10 × 25 × 9 mm for patient 1 and 2, respectively, while resected tissue size was 10 × 24 × 8 mm and 9 × 24 × 8 mm in patient 1 and 2, respectively. After TASM procedure, SAVR was performed with bioprosthetic valve. Postoperative course of both patients was uneventful with no evidence of complete atrioventricular block, septal perforation, or blood flow acceleration at the LVOT.

Discussion

Preoperative planning based on cardiac CT images is safe and useful for guiding adequate myectomy and preventing associated complications in patients with subaortic septal hypertrophy associated with AS.

The Role of the Submitral Apparatus in Hypertrophic Obstructive Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease, is characterized by unexplained hypertrophy of any myocardial segment, and has a prevalence of 0.2% to 0.5% among the general population. As one of the phenotypes of hypertrophic cardiomyopathy, left ventricular outflow tract obstruction (LVOTO) is associated with high morbidity and mortality, including cardiac death. The integration of various factors, including septal hypertrophy, malformation of the mitral valve apparatus, and an anomalous mitral subvalvular apparatus, may contribute to the occurrence of LVOTO. Previous studies have thoroughly discussed the role of the mitral valve in the mechanisms of systolic anterior motion and LVOTO. Recent studies have shown the importance of determining the potential mechanism of the submitral apparatus in inducing systolic anterior motion and LVOTO. The authors review recent advances in knowledge regarding the submitral apparatus of patients with hypertrophic cardiomyopathy.