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Is dyspnea due to “diastolic dysfunction” different from systolic dysfunction?

Posted Nov 13 2012 5:42am

No  body wouldn’t  ever have  differentiated   dyspnea with reference to  systolic and diastolic dysfunction .I have made some  observations  in certain group  of patients  during EST  . I do not know how far one would agree  with this .

For  the same amount of  stress or work load persons with  systolic dysfunction  behave differently . However ,both will complete the activity but the onset and perception of dyspnea is slightly different in patients with predominant diastolic dysfunction.

Diastolic dyspnea (Dyspnea due to predominant diastolic dysfunction / HFPEF)

  • Delayed dyspnea .  It manifest  well after the exertion is completed.
  • It is more off a struggle to handle the venous return .The forward flow (Arterial circuit )  is relatively well toned and  tuned  and hence fatigue is rare .
  • Typically it has a prolonged recovery time .(? > 1-2 minutes )
  • Is it  less harmful  in terms of longevity ?  May be . . . since it is more related to physical  de-conditioning. Most of the physiological  episodes of dyspnea are probably  diastolic dysfunction  mediated .
  • Dyspnea that is triggered  in diastole is also dependent very much  on the  heart rate .If the heart rate fail to reach the baseline the recovery of dyspnea is also delayed
  • Some believe , physiological dyspnea should disappear within 30-60 seconds after termination of activity  .(Highly  arbitrary!)

The pressure volume loop in various forms of heart disease will determine the degree of myocardial stretch and the resultant dyspnea .Image source : http://www.1cro.com/medicalphysiology/chapter10/chap_10.htm

Systolic dyspnea (Dyspnea due to predominant systolic dysfunction )

  • Patients with primary systolic pump failure experience dyspnea very early into exercise  .
  • Much of dyspnea  occur during activity itself .
  • Exercising muscles show hypoxia  and hence  fatigue is conspicuous .
  • Recovery  of dyspnea is relatively immediate as the activity is stopped .Demand from exercising  muscle is  significantly dropped.
  • If the venous return is well handled by the ventricles the  recovery phase is more comfortable .

Summary

In primary diastolic dysfunction  ,the maximum stress  to ventricle occurs  when  the venous return peaks that usually happen in the exercising muscles , as they shed  vaso-dilatory  property  in post exertion phase .

Management Implication

 Fluid overload ,  Tachycardia   are more  related to diastolic dysfunction .(Beta blockers by prolonging  the diastole can , provide important relief of dyspnea in diastolic dysfunction (In HOCM patients   this action could be  more important that  the much hyped negative inotropism !)

Final message

Dyspnea is  a complex cortical  perception , influenced by filling pressure of heart, stretch receptor in lungs , respiratory and   exercise muscle . It is further impacted by number of biochemical parameters (Lactate/ O2 etc )

Of-course  , it could be a  far fetched  imagination to  to split dyspnea  mechanism with reference to cardiac cycle. Combinations  of both  systolic and diastolic dysfunction is the norm in many  cardiac conditions . Hence the issue may be redundant .

However  , I believe  we need   more insight in the  pathogenesis of  this ,  “most important  symptom”   that emanate  from the heart .


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