Posts Tagged ‘ejection fraction’

What   are the factors other than EF %  that determine  functional capacity in cardiac failure ?

In our experience we have found the following factors  contribute immensely to the functional capacity of cardiac failure patients

  1. LV  filling  defects  (30 % of DCM have significant LV relaxation defects )*
  2. Integrity of  RV  function
  3. Mitral valve  competence(Even a mild MR can be important .It lowers the threshold for pulmonary congestion  )
  4. Severity of Pulmonary hypertension
  5. Lung Function *(Restrictive PFT common , gross cardiomegaly can reduce lung space )
  6. Basal exercise capacity .
  7. Skeletal muscle  function (Mitochondrial training )*
  8. High body weight
  9. Will power and self esteem *
  10. Spouse support and motivation

* May  have  major Impact on functional capacity

Final message

Physicians and even cardiologists are   obsessed  with EF %  to a large extent . My guess is , it   is not likely to end in the near future . The irony is ,  we have passed it  to our  colleagues  (Like anesthetists !)  and patients as well .(  for various reasons )

                        Please remember  , there are at-least 10 factors  that are  important  in the genesis of  symptoms of heart failure  . The list can extend  further  if we include  like associated renal  dysfunction , hemoglobin concentration  , etc .

Even though LV pump primarily determines  the ultimate outcome in cardiac failure ,  it is unwise  to  blame the EF %  for all the suffering  . If only  we realise this fact , one  can take  appropriate  measures .

**   Paradoxically modalities aimed to improve LVEF by positive inotropics has never been shown to improve the outcome .In-fact , there is more evidence for the contrary !

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Can the LV  ejection fraction change with every  heart beat  ?

EF % is one of  the  glamorous  cardiac functional indices that has  caught  the  imagination of both patients and physicians. How accurate it is ? How reproducible it is ? How many methods are available  to arrive at EF % ?

Picture courtesey http://rachel.worldpossible.org/ocw.tufts.edu Munther Homoud, M.D

 How many of us  realise  it can  potentially   change  with  every  heart beat ? *

Apart from the heart rate dependency ,  the echocardiographic error can be amplified  by

  • Difficulty in identifying  the  leading and trialling edges  of endocardium
  • Patient posture errors
  • Edge detection errors in 2D
  • Pap muscle shadowing .
  • Angle errors
  • Sub optimal echo windows  when EF is measured  in the  bed side  in critical care units
  • Mental status of performing sonographer/cardiologist  (One who chops  2D shells hurriedly and obliquely !  )

All these make this index a highly  variable parameter(  next only   to your  city temperature ! ) This happens whether you measure EF  with M Mode, 2D Simpson , 3D volumetric etc .

* The term  “beat to beat” changes may be  a little exaggerated  statement .It is used   to convey the point of   ” huge  variability” of this parameter.  It  means there can be variations of EF %  with varying heat rate.

The heart is not an Independent organ rather, it is a slave to preload and afterload !

How to overcome the limitation  of EF ?

To overcome this  error a new  parameter called myocardial performance index (MPI) which accounts for heart rate came into vogue . (Did it come really ? Ihaven’t seen a single cardiologist  do this in his clinic ) . 3D volumetrics,  velocity vector imaging , and many other innovations has been added.  Nothing  was  able to replace the EF % . Because of complexities in the newer  modalities  most cardiologists (including  the author  )  continue to romance  the  much flawed EF %  .

Simplicity  shall   reign supreme   .  .  . in spite of  inaccuracies ,  in any walk of life  !

 How does  EF  change  beat to beat ?

The answer is simple . The contractility of heart is dependent   upon the previous  diastole ,  during which heart fills. Heart is primarily an elastic organ. Whenever the  filling is  is more   ventricle is stretched  more ( diastolic filling is the stretch ) and the subsequent force of contraction is more . This is the basis of famous frank starling law.

LV filling is dependent on RV filling which in turn depend on venous return ..Venous return is a function of  vascular tone and the persons physical activity .

Apart from this  adrenergic drive make the heart contract vigorously . This is the reason ,  many patients  with  severely compromised  LV function  in ICU  , supported  with  inotropic agents  show vigorous contraction of heart .(Basis of doubutamine  stress test )

** Every one of us is aware about the huge influence  the preload  has ,  on LV contractility .  Surprisingly,  it   can also  swing  with changing  after load . This fact is often  under recognised .This is called Anrep effect .

So , imagine the scenerio . . .the heart is simply  a “squeezing- slave”  of   pre load and  after load  !  . . . And still we are happy with assessing the cardiac function ,  in isolation without giving any respect to the loading conditions.

Final message

EF ,  would rank  first among all  medical  investigations ,  that is  significantly  flawed , still  continue  to  enjoy huge popularity  ! It has little value as a  screening   test for assessing  LV function in  general  population . But ,  it  has an  important role to assess  the damage following   MI and in  the  follow up of patients with   significantly  compromised LV function.

Cardiologist are aware of this fact ,  but most non cardiologists , especially  Anesthetists  and Surgeons  revere  the  EF% with    sanctity  . This is definitely un-called for . It is the duty of the cardiologists to pass on  this  message to their colleagues in other fields.

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The long standing controversy about diastolic heart failure is settled !

The perception that diastolic heart failure ( Now renamed as heart failure with preserved EF ) is less dangerous than systolic HF has been exposed by this land mark study by Owan TE, in 2006 (nejm) But unfortunately this information is not yet fully disseminated among the physician community. Hence this post, with due acknowledgment to NEJM & Owan et all.

Experts from the article

“The nosology of heart failure has been the
subject of much current debate, and some extreme
positions have been taken. The observation
that 22 to 29 percent of patients with diastolic
heart failure die within one year of hospital
discharge, and 65 percent die within five years,
is a reminder that we are facing a lethal condition,
regardless of its name. Owan et al. also
show that, in recent years, there has been little
improvement in survival rate among patients with
diastolic heart failure, in contrast to the improvement
in survival rate over time among patients
with systolic heart failure”

Have a look at the survival curve below, almost similar , surprise surprise ! DHF survival is not only worse ( in many ), than systolic CHF and further they respond poorly to treatment, compared to conventional systolic CHF .

Click below for the link to full text article

Short abstract :

Trends in prevalence and outcome of heart failure with preserved ejection fraction.

Cardiorenal Research Laboratory, Mayo Clinic College of Medicine, Rochester, Minn 55905, USA.

BACKGROUND: The prevalence of heart failure with preserved ejection fraction may be changing as a result of changes in population demographics and in the prevalence and treatment of risk factors for heart failure. Changes in the prevalence of heart failure with preserved ejection fraction may contribute to changes in the natural history of heart failure. We performed a study to define secular trends in the prevalence of heart failure with preserved ejection fraction among patients at a single institution over a 15-year period. METHODS: We studied all consecutive patients hospitalized with decompensated heart failure at Mayo Clinic Hospitals in Olmsted County, Minnesota, from 1987 through 2001. We classified patients as having either preserved or reduced ejection fraction. The patients were also classified as community patients (Olmsted County residents) or referral patients. Secular trends in the type of heart failure, associated cardiovascular disease, and survival were defined. RESULTS: A total of 6076 patients with heart failure were discharged over the 15-year period; data on ejection fraction were available for 4596 of these patients (76 percent). Of these, 53 percent had a reduced ejection fraction and 47 percent had a preserved ejection fraction. The proportion of patients with the diagnosis of heart failure with preserved ejection fraction increased over time and was significantly higher among community patients than among referral patients (55 percent vs. 45 percent). The prevalence rates of hypertension, atrial fibrillation, and diabetes among patients with heart failure increased significantly over time. Survival was slightly better among patients with preserved ejection fraction (adjusted hazard ratio for death, 0.96; P=0.01). Survival improved over time for those with reduced ejection fraction but not for those with preserved ejection fraction. CONCLUSIONS: The prevalence of heart failure with preserved ejection fraction increased over a 15-year period, while the rate of death from this disorder remained unchanged. These trends underscore the importance of this growing public health problem. Copyright 2006 Massachusetts Medical Society.

Other interesting article

Heart failure with preserved ejection fraction: dangerous, elusive, and difficult.

Eur Heart J. 2008 Feb;29(3):339-47. Nielsen OW, Køber L, Torp-Pedersen C.

BMJ editorail 2009


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