Posts Tagged ‘low gradient lv dysfunction’

Degenerative Aortic stenosis occur with either normal  or congenitally malformed/ bicuspid valve.This contributes to the major chunk of  aortic valve surgeries and interventions (TAVR) in elderly population  . The optimal  timing of aortic valve replacement in patients with AS is debatable inspite of  well formed guidelines.

Three factors determine it .Symptoms , severity of aortic valve narrowing  and the tactness of LV function .The last parameter is a tricky one .We used to think in the past , severe LV dysfunction is a contraindication to aortic valve surgery. Now we realise ,however severe the LV dysfunction may be , relieving the obstruction will benefit  the patient and  the LV function is  also  likely to improve.

Cardiac physicians  face a dilemma when confronted with a patient  with low gradient and severe LV dysfunction .In this situation they are advised to do doubtamine stress Echo and watch for the gradient .If the gradient  increases that would  imply true fixed stenosis . (In pseudo aortic stenosis increased contractility opens the aortic valve and gradient will fall )

While this concept appears simple .There  are few  important issues that goes unaddressed  as we have not yet fully understood the  mechanism of LV dysfunction in aortic stenosis .(Link to mechansim of LV dysfunction in Aortic stenosis.)

At what degree of aortic stenosis LV goes down fighting and fail to generate the required  gradient ?

Myocardial function  and behaviour at times of hemodynamic stress can be highly  variable and most of us believe it is determined primarily by the genetic switches of myosin and other contractile elements .This is naturally proven at times of hypertensive left ventricular failure (Only in a fraction of the hypertensive population  LV is set to fail  when BP acutely raises.)

Proposed concept

Considering the complexities in cardiac mechanics , hemodynamics (and not to forget the vast control exhibited by genetic imprints over the hemodynamic behavior of LV) , it seems highly plausible even mild degrees of Aortic stenosis can inflict significant myocardial dysfunction in certain patients . Hence the phenomenon of pseudo aortic stenosis needs further critical analysis If this is proven to be true there could be a realistic indication for aortic valve intervention even in patient with low gradient / true Mild AS with LV dysfunction.
A word of caution is required .Relying too much (Which we often do ) on gradients in the assessment of aortic stenosis has skewed our common sense. Its wiser to have a  meaningful look at the valve morphology . A normal appearing  valve in 2D can never cause significant stenosis. Pressure recovery phenomenon also is to be given due respect as it over estimates gradient .This will effectively avoid surprises and guilt on table when we find a relatively good looking valve posted for AVR /TAVI

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