### Date : 2024-11-01 19:01 ### Topic : Hypertrophic cardiomyopathy, H-CMP #cardiology #medicine ---- **Hypertrophic Cardiomyopathy (HCM)** is a genetic disorder characterized by abnormal thickening of the heart muscle, particularly the **left ventricle**. This thickening can interfere with the heart’s ability to pump blood effectively and increase the risk of arrhythmias and sudden cardiac death. ### 1. **Pathophysiology and Mechanism** - **Genetic Mutations**: HCM is primarily inherited in an **autosomal dominant** pattern, meaning a mutation in one gene from either parent can cause the condition. It is commonly linked to mutations in genes encoding **sarcomeric proteins** like **beta-myosin heavy chain** and **myosin-binding protein C**. - **Myocyte Hypertrophy**: These genetic mutations lead to **abnormal thickening (hypertrophy) of the myocardial cells**, especially in the left ventricle and interventricular septum. - **Myocardial Disarray**: The heart muscle cells are disorganized and misaligned (known as myocyte disarray), which can disrupt normal electrical conduction, increasing the risk of arrhythmias. - **Left Ventricular Outflow Tract (LVOT) Obstruction**: In many cases, the thickened septum obstructs blood flow out of the left ventricle during contraction, known as **obstructive HCM** or **hypertrophic obstructive cardiomyopathy (HOCM)**. Not all cases of HCM have obstruction, though. ### 2. **Types of Hypertrophic Cardiomyopathy** - **Obstructive HCM (HOCM)**: The thickened septum causes obstruction of the LVOT, which impedes blood flow from the left ventricle to the aorta, especially during physical exertion. - **Non-Obstructive HCM**: There is significant hypertrophy but no obstruction in the LVOT. Symptoms may still occur due to impaired filling of the thickened ventricle. ### 3. **Symptoms of Hypertrophic Cardiomyopathy** Symptoms vary based on the severity and type of HCM, and some individuals remain asymptomatic. Common symptoms include: - **Dyspnea (Shortness of Breath)**: Due to increased stiffness of the left ventricle, which impairs filling and increases left atrial pressure. - **Chest Pain (Angina)**: Can occur due to increased oxygen demand from the thickened myocardium. - **Syncope or Near-Syncope**: May result from arrhythmias or from LVOT obstruction, particularly during exercise. - **Palpitations**: Caused by arrhythmias such as atrial fibrillation or ventricular arrhythmias. - **Sudden Cardiac Arrest**: HCM is a leading cause of sudden cardiac death, especially in young athletes, due to ventricular arrhythmias. ### 4. **Diagnosis of Hypertrophic Cardiomyopathy** Diagnosis involves imaging and sometimes genetic testing to confirm HCM and assess the severity. - **Echocardiogram (Echo)**: - **Key Diagnostic Tool**: An echocardiogram is used to visualize ventricular wall thickness, the presence of LVOT obstruction, and the function of heart valves. - **Septal Hypertrophy**: The septum is typically >15 mm thick in HCM (normal is <12 mm), with a classic asymmetric thickening pattern. - **Doppler Echo**: Used to measure any outflow obstruction. - **Electrocardiogram (ECG)**: - Often shows signs of **left ventricular hypertrophy (LVH)**, abnormal Q waves, and possibly atrial enlargement. - Can also reveal arrhythmias that are common in HCM. - **Cardiac MRI**: Provides detailed images of the heart’s structure and is especially useful in evaluating myocardial fibrosis, which can contribute to arrhythmias. - **Genetic Testing**: Used to identify mutations in known HCM-related genes, especially for family screening. ### 5. **Management of Hypertrophic Cardiomyopathy** Treatment focuses on symptom relief, reducing the risk of sudden cardiac death, and preventing complications. - **Medications**: - **Beta Blockers**: First-line treatment to reduce heart rate and improve diastolic filling. Beta blockers also help reduce the dynamic obstruction in HOCM. - **Calcium Channel Blockers (e.g., Verapamil)**: Used in patients who cannot tolerate beta blockers; helps relax the heart muscle and improve filling. - **Disopyramide**: An antiarrhythmic that can also reduce LVOT obstruction by decreasing contractility. - **Management of Obstructive HCM**: - **Septal Reduction Therapy**: In symptomatic patients with significant LVOT obstruction, two main interventions can be considered: - **Septal Myectomy**: Surgical removal of part of the thickened septum to relieve obstruction. - **Alcohol Septal Ablation**: Injection of alcohol into a small coronary artery that supplies the thickened septum, causing controlled myocardial infarction and reducing obstruction. - **Implantable Cardioverter-Defibrillator (ICD)**: - **Indicated in High-Risk Patients**: Patients with a family history of sudden cardiac death, history of syncope, or documented ventricular arrhythmias may need an ICD to prevent sudden cardiac arrest. - The ICD detects and terminates life-threatening arrhythmias, such as ventricular fibrillation, by delivering a shock. - **Lifestyle Modifications**: - **Avoid Vigorous Exercise**: Intense physical activity can provoke arrhythmias and worsen LVOT obstruction. - **Hydration and Avoidance of Dehydration**: To maintain optimal filling pressures. - **Avoid Medications that Increase Contractility**: Certain drugs (like digoxin) and diuretics that reduce preload should be avoided, as they may exacerbate LVOT obstruction. - **Anticoagulation**: Patients with HCM who develop atrial fibrillation are at a high risk of thromboembolism and may require anticoagulation therapy. ### 6. **Risk Stratification and Prognosis** - **Risk of Sudden Cardiac Death**: Certain factors increase the risk of sudden cardiac death, including: - Family history of sudden cardiac death. - History of syncope or near-syncope. - Extreme left ventricular hypertrophy (wall thickness >30 mm). - Presence of ventricular arrhythmias. - **Regular Monitoring**: Patients with HCM require regular follow-up with echocardiograms and possibly Holter monitors to detect arrhythmias and assess changes in heart structure. - **Family Screening**: First-degree relatives should be screened with echocardiograms and possibly genetic testing if a mutation is identified. ### Summary - **Hypertrophic Cardiomyopathy** is a genetic heart muscle disorder with ventricular hypertrophy, particularly of the septum, which can obstruct blood flow. - **Symptoms**: Include dyspnea, chest pain, syncope, and palpitations, with risk of sudden cardiac death due to arrhythmias. - **Diagnosis**: Primarily through echocardiography and ECG, sometimes with genetic testing. - **Management**: Includes beta blockers or calcium channel blockers, septal reduction in obstructive cases, and ICDs for high-risk patients to prevent sudden death. ### Reference: - ### Connected Documents: -