What is the mechanism of LV dysfunction in severe longstanding aortic stenosis ?
Posted Jul 07 2009 5:58pm
Aortic stenosis is one of the commonest valvular heart disease.Degenerative, calcific aortic valve is the underlying pathology . Many of the degenerative aortic valve is thought to be a sequel to bicuspid aortic valve .The exact incidence of BCAV contributing to degenerative aortic stenosis is difficult to determine as many of these leaflets lose it’s identity . Rheumatic aortic stenosis continues to be a problem in developing world.Though ,primary aortic stenosis is the dominant theme , some amount of aortic regurgitation is commonly observed in all these conditions.
Apart from the severity of aortic stenosis there are two other important factors that determine the long term outcome.
LV function
Associated CAD.
Timing of surgery
Left ventricular dysfunction is a common companion in severe aortic stenosis .Once the LV dysfunction sets in , there is a rapid decline in the clinical outcome.Some of these patients have very severe LV dysfunction (EF< 30%) .
LV dysfunction , underestimates the true gradient across LV . Cardiologists are often preoccupied with assessment of true severity aortic stenosis in the presence of LV dysfunction .Sophisticated dobutamine stress echo, is supposed to help us.
Unfortunately cardiology literature has little to offer regarding the mechanism of LV dysfunction in critical aortic stenosis
Some of the possibilities are
Sub endocardial contractile dysfunction due to long standing high wall stress.
Finally it could be a “Pseudo LV dysfucntion” ie, simple mechanical stunning due to high afterload.This is a distinct possibility as some of these patients with worst LV function recover fully following AVR.
Combination of the above mechanisms can occur
How will you determine whether , the LV dysfunction of aortic stenosis is reversible or irreversible ? Is viability an issue in LV dysfunction associated with aortic stenosis ?
Even though it is logical to think LV dysfunction of CAD and LV dysfunction of aortic stenosis are similar it may not be so ! ( Unless the LV dysfuntion due to obstructive coronary disease coexists)
Following rules need to be applied in patients with AS and severe LV dysfunction.
Every patient with critical aortic stenosis should undergo CAG.
The question of reversible vs irreversible LV dysfunction generally need not arise.
There is no better way to predict the recovery of LV function other than the trial of relieving the obstruction.
So ,all patients* irrespective of any degree of LV dysfunction shall undergo AVR
If there is obstructive CAD they need to be taken for AVR with CABG
* AVR is probably contraindicated, in systemically ill & co morbid patients , with grossly dilated ventricles. Here balloon aortic valvotomy and possibly PVR(Percutaneous valve replacement) could be an answer.
Final message .
LV dysfunction of aortic stenosis is a poorly understood phenomenon. Since it is very difficult to predict whether it’s reversible or irreversible , real world clinical experience would suggest there is no need to predict it at all ! and every one should have AVR irrespective of their LV function.
Aortic stenosis is one of the commonest valvular heart disease.Degenerative, calcific aortic valve is the underlying pathology . Many of the degenerative aortic valve is thought to be a sequel to bicuspid aortic valve .The exact incidence of BCAV contributing to degenerative aortic stenosis is difficult to determine as many of these leaflets lose it’s identity . Rheumatic aortic stenosis continues to be a problem in developing world.Though ,primary aortic stenosis is the dominant theme , some amount of aortic regurgitation is commonly observed in all these conditions.
Apart from the severity of aortic stenosis there are two other important factors that determine the long term outcome.
Left ventricular dysfunction is a common companion in severe aortic stenosis .Once the LV dysfunction sets in , there is a rapid decline in the clinical outcome.Some of these patients have very severe LV dysfunction (EF< 30%) .
LV dysfunction , underestimates the true gradient across LV . Cardiologists are often preoccupied with assessment of true severity aortic stenosis in the presence of LV dysfunction .Sophisticated dobutamine stress echo, is supposed to help us.
Unfortunately cardiology literature has little to offer regarding the mechanism of LV dysfunction in critical aortic stenosis
Some of the possibilities are
How will you determine whether , the LV dysfunction of aortic stenosis is reversible or irreversible ? Is viability an issue in LV dysfunction associated with aortic stenosis ?
Even though it is logical to think LV dysfunction of CAD and LV dysfunction of aortic stenosis are similar it may not be so ! ( Unless the LV dysfuntion due to obstructive coronary disease coexists)
Following rules need to be applied in patients with AS and severe LV dysfunction.
* AVR is probably contraindicated, in systemically ill & co morbid patients , with grossly dilated ventricles. Here balloon aortic valvotomy and possibly PVR(Percutaneous valve replacement) could be an answer.
Final message .