Posts Tagged ‘mechanism of dyspnea of in hocm’

The major mechanism of exertional dyspnea in HOCM is due to

  1. Hypercontractile LV
  2. LVOT obstruction
  3. Diastolic dysfunction
  4. Mitral regurgitation
  5. Unrelated to HOCM

Answer : 3*

*This has been proven by a simple fact , dyspnea continues to be  a prime symptom in both obstructive as well as non obstructive HCM

Though LVOT obstruction appears to be the core issue , the myocardial disarray is a global one and lies scattered .That is why , myomectomy , septal reduction , may not reduce the symptoms  grossly as one would expect.

Paradoxically , preload reduction with diuretics  (That works well  for most  dyspnea with  raised LVEDP) ,  is vested with the risk of worsening the symptoms in HOCM . Diuretics underfill the  LV and tend to aggravate dynamic LVOT obstruction.

Probably ,the best way to reduce  symptom of dyspnea is to keep the heart rate low with betablocker.Further, betablockers smoothen the LV wall stress and calm down the LV baroreceptors which  indirectly suppress the  afferent input in  the brainstem dyspnea circuit.

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