Which of the following findings expected on microscopic examination of biopsy from hea showing ventricular hyperophy with asymmetric septal thickening
**Core Concept**
Ventricular hypertrophy with asymmetric septal thickening is a characteristic feature of hypertrophic cardiomyopathy (HCM), a primary myocardial disorder that leads to thickening of the heart muscle, particularly affecting the interventricular septum. This condition is often associated with genetic mutations that affect the structure and function of cardiac myocytes.
**Why the Correct Answer is Right**
In HCM, the interventricular septum is disproportionately thickened, which can lead to obstruction of the left ventricular outflow tract (LVOT). Microscopically, this is associated with an increase in the number of myofibrils and an accumulation of myosin and actin filaments within cardiac myocytes. The myocardial fibers may also exhibit disorganized arrangement and an increase in the number of fibroblasts and collagen deposition. The interstitial fibrosis and disarray of myocytes contribute to the pathophysiology of HCM.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly related to the microscopic findings in HCM. While fibrosis is a feature of HCM, it is not the primary characteristic of ventricular hypertrophy with asymmetric septal thickening.
**Option B:** This option is incorrect as it is more characteristic of cardiac amyloidosis, where there is an accumulation of amyloid fibrils in the myocardium, leading to restrictive cardiomyopathy.
**Option C:** This option is not relevant to the microscopic findings in HCM. While cardiac fibrosis can be seen in various conditions, it is not a specific feature of ventricular hypertrophy with asymmetric septal thickening.
**Clinical Pearl / High-Yield Fact**
In HCM, the asymmetric septal thickening can lead to dynamic obstruction of the LVOT during exercise or physical exertion, resulting in symptoms such as chest pain, shortness of breath, or syncope. This is a classic clinical correlation that students should remember.
**Correct Answer: B. Cardiac amyloidosis is characterized by the accumulation of amyloid fibrils in the myocardium, leading to restrictive cardiomyopathy and is not associated with ventricular hypertrophy with asymmetric septal thickening.**