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Posts Tagged ‘mitral valve function’

There are many  organic causes of mitral regurgitation. ( Ischemic , degenerative , valvular , cardiomyopathy etc.) It is not  rare for  pure  electrical events to result in valvular regurgitation.   A 70year old  man  with SHT   presented  with palpitation  and exertional dyspnea  .He was  later referred  for  Echocardiography.  Echo revealed LVH with intermittent MR and moderate LV dysfunction.

His ECG looked like

Ventricular ectopic recorded in bi-geminal rhythm

His  echocardiogram showed

 

His echo showed randomly timed mitral regurgitation was detected .See the Doppler MR jets below.

We know ventricles are integral  part of mitral valve apparatus  .Hence  it  wouldn’t  be a surprise to note  abnormally timed ventricular contraction  can  have a major impact  on mitral valve function.

When ventricles  prematurely begin  to contract  ( As  during  VPDs) it  interferes with  opening of mitral valve. In other words every VPD  technically imparts a  sort of  diastolic dysfunction !

VPDs occur in which part of cardiac cycle ?

VPDs  occur  either in early   or mid  diastole . Thank fully VPDs can not occur in systole . (Refractory period )

What would be the status of mitral valve at times of  VPDs?

Though it depends upon the timing of VPD ,  generally it interrupts the rapid inflow period of diastole .

In fact ,  it converts the cardiac  cycle from diastole to a partial systole or  a combination( fusion ) of diastole   and systole ! *

More MR jets are visualised than LV filling waves . Note the some of the E waves are sandwiched between two MR jets. ECG gating should have made this image more interesting .Any way , we have good MR jets to time systole nicely

* Is that a funny  imagination  ?

During   diastole ,  if  LV suddenly  begins  to contract   instead of  receiving the blood  ,  what will happen ?

VPDs are such a common arrhythmia , we  rarely  wondered  ,  it can have a dramatic  consequence  in a any  given cardiac cycle .While   the cardiologists think too  technically  their  patients observe with  shrewd  sense and tell us clearly  what  they feel  is  actually a   missed beat !

(Yeh  . . .  how simple  they describe the complex  hemo-dynamics  of  missing  diastole !)  .They also tell  us ,  next systole is felt as big thump as palpitation . (Post VPD potentiation )

Just imagine ,  if a patient  has  multiple VPDs  with  different  coupling intervals   that fall in different location of diastole  also  interspersed with sinus beats ,   how chaotic  would be the  the  mitral   filling .

This is what  is recorded in the above patient with multiple random MR jets .

Why all VPDs do  not cause MR ?

The timing is critical .We know all VPDs do  not generate a powerful contraction to cause MR. Atrial fibrillation, Prolonged PR intervals , heart blocks , critically raised LVEDP all can influence the trans mitral gradient . In fact these situation can result in  an  entity called diastolic MR that would be discussed later.

Can  VPD induced MR be  referred to  as diastolic MR ?

When VPDs  occur  in  diastole  , it  interrupts the diastole  and a new systole begins. In any  particular point of time there will be  leak into the LA  if the mitral valve is open .This is technically a new systole but in true sense it is the diastole of  the  previous beat . I wonder , whether   VPD induced MR  may be referred  to as one  form of  diastolic MR.  Of course ,  this MR can spill over to true  systole as well .

This also  makes  sense (Non !) as many of the VPDs do not open the  aortic valve ,   hence technically we can’t call the phase reset  by  all  VPDS   as a true systole !

What is the effect of VPDs  on pulmonary venous flow ?

Left atrial  cannon waves can occur that can elevate PCWP .This is the prime reason for resting or  exertional  dyspnea in these patients. Some may get a paradoxical relief  during exertion   as  exercise  suppress VPDs which are frequent at rest.

If VPDs can seriously interfere with mitral valve function , why  they are  often  considered benign  ?

VPDs are well tolerated* as long as  the  LV function is intact.  If VPDs are associated with  LV dysfunction  it  can initiate a vicious cycle of   hemodynamic deterioration .  Multiple VPDs  if left untreated can lead to progressive LV dilatation  in a  significant population .  Hence patients with  recurrent VPDS need some sort of  follow up. It  makes good medical sense to suppress VPDs in the long run. (Of course the  available anti VPD  drugs  are not very safe  !  The search for non toxic ,  ideal drug should go on !)

*”Well tolerated VPDs”   in no way  means  normal physiology.  Read a related article in my site.  “3 minutes crash course on VPDs”

Final message

VPDs  though considered  largely benign , can lead to dramatic  alterations in the  functions  of mitral valve , especially in diseased hearts.

We  must  realise  when ventricular  ectopic beats occur frequently  , it  interfere with the  both opening and closing of mitral valve.

It is really surprising  ,  the literature is  devoid of  major studies  about the  impact of  VPDs on  mitral valve  physiology . . . rather pathology !

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