What exactly is hypertrophic cardiomyopathy (HCM)?
Hypertrophic cardiomyopathy (HCM) is a complicated form of coronary disease which affects the heart muscle.
Thickening of the heart muscle (myocardium) happens most typically in the septum. The septum is the muscle wall that divides the right and left aspect of one’s heart. Difficulties happen when the septum involving the heart’s lower chambers, or ventricles, is thickened.
The thickened septum might result in a narrowing that will obstruct or lessen the blood circulation in the left ventricle to the aorta – a state called “outflow tract obstruction.” The ventricles must pump more difficult to get the better of the narrowing or blockage. Such a hypertrophic cardiomyopathy could be called hypertrophic obstructive cardiomyopathy (HOCM).
HCM additionally may cause thickening in different sections of the heart muscle, including the backside of the heart known as the apex, right ventricle, or throughout the whole left ventricle.
Stiffness in the left ventricle happens because of cellular changes that happen in one’s heart muscle when it thickens. The left ventricle can’t fill with blood and loosen generally. There’s not as much oxygen-rich blood pumped to the muscles and organs, as there is less blood by the end of filling. The stiffness in the left ventricle causes pressure to raise in one’s heart and can cause the symptoms described below.
Mitral valve changes: The narrowing of the left ventricular outflow tract interrupts the appropriate role of the mitral valve, causing outflow obstruction and heightened pressure in the left ventricle.
The obstruction is caused by the mitral valve hitting the septum. When this happens, the mitral valve often flows, inducing the blood to return to the left atrium.
Mobile changes, or changes in the cells of one’s heart muscle, happen with HCM. By way of a microscope, the cells seem disorganized and unusual (called “disarray”) instead of being arranged and parallel. This disarray can cause changes in the electric signals going through the low chambers of the heart and result in ventricular arrhythmia (a form of abnormal heart rhythm).
Signs and symptoms
Signs of HCM can are the following:
- Unexpected cardiac death (the most dreadful presenting manifestation)
- Dyspnea (the most frequent presenting symptom)
- Syncope and presyncope
- Orthopnea and paroxysmal nocturnal dyspnea (early hints of congestive heart failure [CHF])
- CHF (comparatively unusual but occasionally seen)
Physical findings might range from the following:
- Double apical pulsation or triple apical pulsation (less common)
- Jugular venous beat showing a notable a wave
- Double carotid arterial beat
- Apical precordial impulse which is displaced laterally and typically is abnormally enlarged and strong
- Systolic ejection crescendo-decrescendo murmur
- Holosystolic murmur in the apex and axilla of mitral regurgitation
- Diastolic decrescendo murmur of aortic regurgitation (10% of patients)
No special lab blood tests are expected in the workup. Genetic testing isn’t yet widely accessible but is becoming increasingly so.
Two dimensional (2D) echocardiography is diagnostic for HCM. Findings could be summarized as follows:
- Unusual systolic anterior leaflet movement of the mitral valve
- Left ventricular hypertrophy (LVH)
- Left atrial enlargement
- Little ventricular chamber size
- Septal hypertrophy with septal-to-free wall ratio greater than 1.4:1
- Mitral valve prolapse and mitral regurgitation
- Reduced midaortic flow
- Partial systolic closure of the aortic valve in midsystole
Other imaging modalities that might be useful include the following:
- Torso radiography
- Radionuclide imaging
- Cardiac magnetic resonance imaging: Especially useful when echocardiography is questionable, especially with apical hypertrophy
Electrocardiographic findings might range from the following:
- ST-T wave abnormalities and LVH (common)
- Axis deviation (right or left)
- Conduction abnormalities (P-R prolongation, bundle-branch block)
- Sinus bradycardia with ectopic atrial rhythm
- Atrial enlargement
- Unusual and outstanding Q wave in the anterior precordial and lateral limb leads, brief P-R time with QRS indicative of preexcitation, atrial fibrillation (poor prognostic indication), plus a P wave abnormality (all unusual)
These diagnostic modalities might also be useful:
- Cardiac catheterization (to decide the level of outflow obstruction, cardiac hemodynamics, the physiology and diastolic qualities of the left ventricle, along with the coronary physiology)
Pharmacologic treatment for HCM may contain the following:
- Beta blockers
- Calcium channel blockers
- Diltiazem, amiodarone, and disopyramide (seldom)
- Antitussives to prevent coughing
These caveats are justified:
- Avoid inotropic drugs if possible
- Prevent sympathomimetic amines and nitrates, except in concomitant coronary artery disease
- Prevent digitalis
- Use diuretics with care
Surgical and catheter-based remedial choices are the following:
- Left ventricular myomectomy
- Mitral valve replacing
- Permanent pacemaker implantation
- Catheter septal ablation
- Positioning of an implantable cardioverter defibrillator