Heart is a dynamic organ . It can alter its force of contraction with every beat according to the needs.Generally it responds to length of previous diastole.This is famously called frank starling law , ie the force of contraction is directly proportional to the end diastolic fiber length. So changing diastolic duration as in atria fibrillation classically result in varying amplitude of LV contraction and pulse volume.
However , the commonest cause for pulsus alternans is due to severe left ventricular systolic dysfunction .There has always been a suspicion about the existance of beat to beat variation in diastolic function as well. We have recently observed a new* explanation for pulsus alternans .We know AV inflow is subjected to respiratory swings . Non respiratory swings in mitral and tricuspid valves are rarely described. This pattern is now increasingly recognised.
These non respiratory swings in the mitral inflow doppler pattern is seen in some of the patients with hypertension and LVH.This probably confirms the existence of beat to beat variability of diastolic function . This phenomenon is relatively a new observation . Such pattern are common in patients who have had a recent hypertensive failure .
Here is a doppler of mitral inflow recorded from a patient with hypertension with LVH .
It is proposed to define a new class of diastolic dysfunction that can be referred to as diastolic mitral inflow alternans .This phenomenon probably indicates a more severe grade of diastolic dysfunction.At the molecular level this is related to undulating flux in the calcium uptake from cytoplasm into SERCA .There is one more possible explanation for diastolic alternans -Left atrial dysfunction .
Occasionally one can visualise a chaotic pattern of diastolic filling waves (e=a e>a a> e ) Such patterns are thought to be markers of impending acute diastolic shutdown .
Further analysis of this mitral doppler inflow pattern will be reported later.
* Though we observed this for the first time , this is not a new phenomenon .There are few reports available in the literature.