The major complications of hypertrophic cardiomyopathy are discussed below:
As a result of thickened heart muscle and structural abnormality of heart cells (myocardial disarray), our heart's conducting system is disrupted resulting in occasional fast or irregular heartbeats. Arrhythmias, if untreated may result in sudden death. Most common arrhythmias occurring in patients with hypertrophic cardiomyopathy are:
Ventricular tachycardia and
Unfortunately, it is often difficult to really predict and detect which people with hypertrophic cardiomyopathy are most prone to these life-threatening, abnormal heart rhythms. That is why if there is any of the risk factors of the following, we recommend our patients to use implantable cardioverter defibrillator(ICD).
The risk factors are:
Left ventricular wall thickness (LVWT) ?30 mm determined by echocardiography,
Family history of HCM-related sudden cardiac death in one or more first-degree relatives, aged <40 years,
Nonsustained ventricular tachycardia on 24 hour Holter electrocardiogram (ECG) monitoring. It is defined as 3 or more beats at heart rate of 100 per minute on 24-hour ECG.
Abnormal blood pressure (BP) response during exercise: BP increase of <25 mmHg or decrease of >20 mmHg (detected in exercise treadmill test).
Implantable cardioverter defibrillator(ICD)is a small battery powered electrical impulse generator that deliver a brief electrical stimulation whenever it detects an arrhythmia in a patient. Like pacemakers, these devices are connected to electrode wires that are passed through femoral vein to the right chambers of the heart and lodged in the apex of the right ventricle.
Hypertrophied heart muscle
Obstructed blood flow
In many people with hypertrophic cardiomyopathy, there is asymmetrical ventricular wall muscle hypertrophy. As a result, the thickened heart muscle causes obstruction to blood flow from the ventricle of the heart to the rest of the body. Whenever there is less blood supply to the brain tissue and the heart there are symptoms of shortness of breath with exertion, chest pain, dizziness and sometimes fainting spells.
Heart failure is the last destination of many of the common cardiac disorders. It happens when the heart is unable to pump enough blood to meet the need of the body. In hypertrophic cardiomyopathy the thickened heart muscle gradually become too stiff to contract and fill effectively which can lead to heart failure. There is chances of both systolic (late stage) and diastolic heart failure in hypertrophic cardiomyopathy .
This is the general rule of hypertrophic heart muscle disorders . In long standing cases, stiff and thickened heart muscle gradually becomes weak and ineffective. Overtime, the ventricle becomes enlarged (dilated). As a result, heart is unable to pump effectively, and heart failure ensues.
Mitral valve disorder
Due to thickened heart muscle, there is not enough space for blood to leave the heart through the narrow space, which in turn causes blood to rush through heart valves more forcefully. This increased force prevent mitral valve (valve between left atria and left ventricle) from closing properly. Eventually, blood leaks backward into the left atrium resulting in mitral valve regurgitation.
What are the steps to diagnose hypertrophic cardiomyopathy ?
At first the doctor would perform a general and physical examination of important systems to have an idea of the disorder.
Most important clinical clues to diagnose hypertrophic cardiomyopathy are:
Jerky character and a double carotid arterial impulse
Venous pressure may not be elevated but may have a prominent 'a' wave
Apex beat is minimally displaced in the initial stage but in advanced stage there may be systolic impairment with dilated left ventricular cavity and displaced apex beat
There will be presystolic impulse giving the impression of a double apical impulse (if in normal sinus rhythm)
Nature of apex beat would be heaving
There may be a systolic thrill palpable in the left lower sternal edge
Heart rhythm may be irregular ( if any arrhythmia)
On auscultation, second heart sound may have reversed splitting and there may be fourth heart sound
The characteristic murmur of hypertrophic cardiomyopathy may be heard:
a. Ejection systolic murmur at the left lower sternal edge which radiates up the sternal edge but not to the carotids (due to left ventricular outflow obstruction)
b. A pansystolic murmur at the apex which radiates to the axilla (due to systolic anterior motion of the mitral valve resulting in mitral regurgitation like murmur)
Any increase in preload will diminish the left ventricular outflow track gradient and hence the murmur (squatting, beta blocking agents).
A decrease in preload will increase the left ventricular outflow track gradient and hence the murmur (valsalva manoeuvre, standing, nitrates, diuretics)
A decrease in afterload will also increase the murmur (vasodilator therapy)
After looking for these finding in the physical examination, your physician will often search for other conditions associated with hypertrophic cardiomyopathy. They are:
Mitral valve prolapse