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Posts Tagged ‘hcm’

Hypertrophic cardiomyopathy (HCM) manifests   with or without obstruction. Obstructive HCM ,  (ie HOCM)  is more often symptomatic .However , the risk of arrhythmias, sudden death, and some degree of diastolic dysfunction are common in both.

ECG, clinical examination are generally  not sensitive to identify obstruction in HCM  .Echocardiogram is the easiest  way to identify  the obstruction (gradients> 3o mmhg across LVOT are considered significant ).LV angiogram ,MRI, CT scans are rarely necessary today.

However , the following clinical clues will help us  to suspect significant obstruction in HCM

History

  • Class  2 or  3 dyspnea.
  • Exertional syncope
  • Exertional angina

Pulse

  • Pulsus bisferiens (Two peaks in systole )

LV apex

  • Sustained , double apical impulse  often indicate obstruction.
  • Presence of Mitral regurgitation ( 20% can have  MR without obstruction due to intrinsic abnormalities of  mitral valve )

* It should  be realised , valsalva induced MR /LVOTO  may occur in many of the non obstructive HCM.

What happens to  clinical signs of obstruction with medical therapy(Beta blockers etc)

One would expect these signs to regress or disappear, but it rarely happens. The pulse , the  murmur show  little change .  This implies , the main mechanism of beneficial effect could be in  heart rate  reduction , and  improvement in the   diastolic properties of left ventricle.

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Hypotension is one of the dreaded complication of acute STEMI.

  • It can be due to either a  mechanical complication or hypovolemia.
  • The hypotension in inferoposterior MI is  often related to enhanced vagal tone and easily correctable with atropine  and fluid  administration.
  • RVMI is the classical example of hypotension that may improve with fluid resuscitation
  • Hypotension,  if  not reversible within 12  hours  ,  is more likely to  represent a more sinister mechanism like pump failure, MR or ventricular  septal tear etc .

A new mechanism for persistent  hypotension is increasingly recognised.

This is due to the

1.Loss of LVOT dynamic activity.

2.Excessive  dynamism of LVOT.

LVOT contractile and ejectile falure

Even though LV  outflow tract  contain  less  contractile myocytes  , it has an important mechanical  job to do. We know , it’s  primary job is that of a  conduit  but  it also  has to  eject the blood into aorta with sufficient force.  In fact, it is thought much of the acceleration of blood velocity occur in LVOT . So, LVOT  plays a key role in maintaining the cardiac index.  An excessively dynamic LVOT will impede the forward blood flow as in HCOM.  Similarly  less dynamic contraction  of LVOT  results in  low velocity propulsion , that interferes with   proper delivery of blood from LV cavity into the aorta .

These factors get amplified in  acute MI , as it is a compromised situation with fluctuating HR and contractility. So a properly functioning  LVOT conduit is  absolutely mandatory.

STEMI due to a proximal LAD obstruction   located can involve the septal .If the first septal branch  happens to be a major one,  there will be  definite impact on the LVOT function.

Excessive dynamism  , LVOT   desynchrony  LVOT collapse .

LVOT has a medial border formed  by IVS , an  anterior surface and  a posterior surface .The lateral border is relatively boundary less , except it is guarded by  the anterior mitral leaflet.

But one should recall , the AML comes towards the LVOT only in diastole . When it comes in systole it becomes a pathological event  called  SAM  (Systolic anterior motion )

The LVOT wall desynchrony can occur in both anterior and posterior MI.In a mulivessel CAD  this can happen when there is disproportionate inferior to anterior wall motion defect.

Management.

  • There is no specific management strategies aimed at restoring LVOT function.
  • Emergency revascularisation will attenuate the mechanical dysfunction
  • Dosage of powerful inotropic agents should be moderated in dynamic LVOT obstruction.
  • Spontaneous recovery  may occur in few

http://circ.ahajournals.org/cgi/reprint/116/5/e110.pdf

Haley et all Mayoclinciproceedings 1999

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How will you refer to a ventricle which is not dilated but still has severe global contractile dysfunction ?

Traditionally cardiomyopathy is classified as

  • Dilated (DCM)
  • Hypertrophic(HCM)
  • Restrictive (RCM)

But there is large group of pateints who do not show any of the above features and still have global hypokinesia  contractile dysfunction. this group has been largely ignored .It could constitute up to 25%of all cardiomyopathy.there can be some overlap between non dialted cardiomyopathy and RCM.

We report our experience here with

non dilated cardiomyopathy click to download PPT

non dilated  cardiomyopathy

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