Hypertrophic cardiomyopathy

In  this  condition, also  known as isidiopathic hypertrophic subaortic stenos, there is cardiac hypertrophy, usually involving the interventricular septum, which in a minority of patients can  lead  to a dynamic left  ventricular outflow obstruction.  In  the   patients with obstruction any  situation that results in a reduction in left ventricular volume (hypovolemia, Valsalva maneuver) increases the  obstruction of the  thickened, non-compliant, “restrictive” ventricle. The  disease has  a genetic basis,  at times affecting families, and involves mutations in  the   coding of  b  cardiac myosin heavy chains. The  majority  of patients are  asymptomatic but  the  condition can  present, usually in young adults, with syncope, sudden death, or  breathlessness. Abnormal cardiac rhythms  are  poorly tolerated and  patients may present with atrial tachyarrhythmias,  leading to  hypotension, as  a result of the  loss  of the  atrial contribution to  filling the  “restrictive” ventricle.

On  physical examination, the  pulse is bisferiens or  “jerky”, with a brisk  arterial upstroke. Blood  pressure is normal and JVP is usually normal. There is a prominent, forceful, left  ventricular impulse.

On  auscultation (Figure),  S1  is normal and S2  is split  normally on  inspiration. There is a prominent S4. A mid  to late  systolic ejection murmur is  heard at  the   left   sternal edge   and  apex. The   murmur typically increases with Valsalva maneuver. When mitral regurgitation is present, an  apical, holosystolic murmur is heard and may  be accompanied by an S3.

The  chest and abdominal examinations are  normal.  There is  no peripheral edema. Electrocardiogram findings are  left  ventricular hypertrophy, ST and T wave  abnormalities, and prominent  septal Q

 Feature Obstructive hypertrophic cardiomyopathy  Aortic valve stenosis
Pulse Bisferiens or “jerky”, with a brisk Slow rising, low volume,
ar terial upstroke and sustained
Murmur Ejection systolic;  increases with Ejection systolic;
Valsalva (which decreases stroke increases with squatting
volume) with or without mitral (which increases stroke
holosystolic volume)

Distinguishing examination features of obstructive hypertrophic cardiomyopathy and aortic valve stenosis

waves  (narrow and deep) caused by hypertrophy of the  septal region (a “pseudo-infarction” appearance). The chest x ray film appearance is normal or cardiac enlargement may  be present. Certain examination features distinguish obstructive hypertrophic cardiomyopathy (subaortic stenosis) from aortic valve  stenosis (Table  above).

The   clinician  needs  to   be   aware   that  hypertrophic obstructive myopathy can  be  found in  young adults; it  may   be  unmasked by inappropriate hypotension associated with atrial arrhythmias (because of restriction of cardiac filling), and the  obstructive variety often has  an  S4 and an  ejection systolic murmur.

Source: Cardiology Core Curriculum A problem-based approach John D Rutherford

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About Blue Star

Medical Student (Future MD)
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