Hypertrophic Obstructive Cardiomyopathy
Hypertrophic obstructive cardiomyopathy is the condition in which myocardium of the left ventricle Hypertrophies which is not due to normal physiological stimulus as seen in diseases like chronic HTN or valve disorder.
In simple words, there is an increased synthesis of actin and myosin protein due to mutation which makes the cardiac muscle hypertrophy in Hypertrophic obstructive cardiomyopathy.
It is most often seen near the septum at the subaortic part which obstructs the blood flow to the aorta and creates a increased pressure inside the left ventricle.
These increased ventricular pressure overtime can lead to concentric Hypertrophic at the left ventricles.
In concentric Hypertrophy myocytes becomes thicker in size where sarcomere are added in parallel with existing sarcomere.
Concentric hypertrophy results in a decreased compliance as ventricles become stiff and failed to relax which leads to diastolic dysfunction.
This picture is showing that how during concentric hypertrophy, sarcomeres laid down in parallel pattern in order to make the myocytes thick to overcome the pressure created during Hypertrophic Cardiomyopathy.
About 60-70% of cases of Hypertrophic Obstructive Cardiomyopathy runs in a family which is due to an autosomal dominant mutation at the gene encoding the sarcomere proteins.
The most notable affected contractile proteins are beta myosin heavy chain and myosin binding protein C.
Patient with chronic hypertension also show left ventricle hypertrophy in response to high blood pressure.
Friedrich ataxia is an autosomal recessive disease associated with trinucleotide repeat can also cause concentric left ventricular Hypertrophy and Septal hypertrophy.
When going through its Pathophysiology, there is an asymmetric Septal Hypertrophy of the left ventricle which failed to relax normally and this can lead to diastolic dysfunction.
Thickened myocardium obstructs blood outflow leaving left ventricle and due to the outflow obstruction, patient shows symptoms of heart failure because blood can't able to get out of the left ventricle hence blood backflow into the lungs which shows a symptoms like Dyspnea ie. difficulty in breathing.
Chest pain is also seen because of outflow obstruction which creates an increased pressure inside the left ventricle as a result there is a decrease in the coronary blood flow which shows the symptoms of chest pain and one more reason for angina is that the Hypertrophic myocardium increases the oxygen demand that creates an chest pain.
Syncope during exertion as also seen as during exercise myocardium contracts even more vigorously that makes the obstruction even greater and that rapidly hampers the blood flow to the brain leading to syncope.
Because of the outflow obstruction as seen in Hypertrophic obstructive cardiomyopathy, the pressure inside the left ventricle rises and blood moves in a high velocity during systole to overcome the obstruction, which many times tug the anterior leaflets of the mitral valve and pull the anterior leaflets forward, hence called systolic anterior motion of the mitral valve.
Systolic anterior motion of the mitral valve overtime damages the mitral valve lead to mitral regurgitation.
A thick abnormal myocardium in patient with Hypertrophic cardiomyopathy also makes them vulnerable to ventricular arrhythmias which can lead to sudden death.
That's why many times a sudden death in athletics is seen as during exercise, catecholamimes also increases which causes the risk of sudden cardiac death in athletics.
The classic histological finding on the biopsy of patient with HOCM is the myofibrillar disarray and fibrosis where the fibrosed myocytes with excessive branching run in a disorganized way.
S4 heart sound is heard with thickened stiff myocardium as seen in left ventricle hypertrophy which is a late diastolic sign.
Systolic ejection murmurs is heard due to outflow tract obstruction which is heard during systolic when blood eject through the Hypertrophic valve. Systolic murmurs are described as crescendo -decrescendo murmurs that is sound gets louder and quiter during systole.
Holosystolic murmurs is also heard as a result to mitral regurgitation.
Here an Echocardiogram shows the obstructed left ventricular outflow tract and the mitral regurgitation as seen in Hypertrophic obstructive cardiomyopathy.
It is very important to avoid high intensity physical exercise among athletics with HOCM as exercise increases the risk for sudden cardiac death in athletics.
Medication like β blockers and non-dihydropyridine Ca2+ channel blocker are beneficial in patient with Hypertrophic obstructive cardiomyopathy because both β blocker and Calcium blocker decreases the contractility which decreases the amount of thickening at the septum below the aortic wall that helps in lessen the obstruction to blood flow.
If syncope occurs in patient then Implantable cardioverter defibrillator is implanted to reduce the risk of ventricular arrhythmia.
In severe cases, septoplasty is also done where some of Septum is removed to relieve the obstruction caused by Hypertrophic obstructive cardiomyopathy.
Nice explanation
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