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ccf

congestive cardiac failure

see also:

introduction

  • cardiac failure is the commonest cause for hospital admission in those aged over 65 yrs
  • prevalence of CCF increases with increasing age and affects about 10% of the population older than 75 years.
  • in spite of significant advances in the treatment of heart failure, mortality rates remain high: 30 to 40 percent of patients with advanced disease and 5 to 10 percent of patients with mild symptoms die within five to 10 years.
  • there are two pathophysiologic types of CCF (or congestive heart failure (CHF))
    • systolic failure (impaired ability to contract) characterised by an ejection fraction < 45%
    • diastolic failure (impaired ability to fill in diastole) which is more poorly quantified and agreed criteria has not been reached
  • the two types have similar symptoms and signs and usually require echocardiography or angiography to discriminate.
  • diastolic heart failure is more common in women and elderly persons and accounts for 25-50% of patients hospitalised with cardiac failure.
  • although patients with diastolic heart failure have a lower annual mortality rate than patients with systolic heart failure, they have a higher rate than the general population.

Framington criteria for Dx of CCF

  • concurrent presence of either 2 major criteria or 1 major and 2 minor criteria:

major criteria

  • paroxysmal nocturnal dyspnea
  • weight loss of 4.5 kg in 5 days in response to treatment
  • neck vein distention
  • rales
  • acute pulmonary edema
  • hepatojugular reflux
  • S3 gallop
  • central venous pressure greater than 16 cm water
  • circulation time of 25 seconds
  • radiographic cardiomegaly
  • pulmonary edema, visceral congestion, or cardiomegaly at autopsy

minor criteria

  • nocturnal cough
  • dyspnea on ordinary exertion
  • a decrease in vital capacity by one third the maximal value recorded
  • pleural effusion
  • tachycardia (rate of at least 120 bpm)
  • bilateral ankle oedema

clinical features of CCF

symptoms

LV failure

  • SOBOE - most sensitive symptom but not specific
  • orthopnoae/PND - more specific but less sensitive (20-30% pts)
  • cough with pink, frothy sputum is highly suggestive

RV failure

  • SOA

signs

  • peripheral edema, jugular venous distention, and tachycardia are highly predictive of CCF but occur in only 10-20% pts.
  • other signs may also occur:
    • hypertension, cold & sweaty skin, pulsus alternans, wheezes, third or fourth heart sounds.
  • CXR only 80% sensitive
  • a negative BNP has 98% NPV
  • a positive BNP is non-specific but more useful if higher values in older people and intermediate pre-test probability - not helpful if low or high pretest probability

systolic heart failure

  • impaired ability of the ventricle to contract resulting in LV ejection fraction < 45%
  • update: consider adding an If current blockers if HR > 77 bpm

diastolic heart failure

diastole

  • The relaxation process has four identifiable phases:
    • isovolumetric relaxation from the time of aortic valve closure to mitral valve opening;
    • early rapid filling after mitral valve opening;
    • diastasis, a period of low flow during mid-diastole; and
    • late filling of the ventricles from atrial contraction
  • Diastole is a complex process that is affected by a number of factors, including:
    • ischemia
    • heart rate
      • heart rate determines the time that is available for diastolic filling, coronary perfusion, and ventricular relaxation.
    • velocity of relaxation
    • cardiac compliance (i.e., elastic recoil and stiffness)
    • hypertrophy
      • hypertrophied ventricle has a steeper diastolic pressure-volume relationship; therefore, a small increase in left ventricular end-diastolic volume (which can occur with exercise, for example) causes a marked increase in left ventricular end-diastolic pressure.
    • segmental wall coordination of the heart muscle.

aetiology of diastolic failure

  • hypertension
    • hypertension is the most common cause and causes LV hypertrophy and increased connective tissue content, both pf which decrease cardiac compliance.
  • ischaemia
    • Hypoxia inhibits the dissociation of myosin-actin crossbridges during muscle relaxation as this requires active transport of calcium ions into the sarcoplasmic reticulum.
  • tachycardia:
    • tachycardia adversely affects diastolic function by several mechanisms:
      • decreases left ventricular filling and coronary perfusion times
      • increases myocardial oxygen consumption
      • causes incomplete relaxation because the stiff heart cannot increase its velocity of relaxation as heart rate increases.
  • AF:
    • atrial fibrillation worsens failure by two main mechanisms:
      • loss of the atrial “kick” in filling the ventricle
      • adverse effects of tachycardia (as above) if rapid ventricular rate
    • note that diastolic failure increases the risk of AF as the raised atrial pressures and distended atria predispose to AF developing.
  • systolic failure
    • residual blood within the ventricles at the end of systole decreases the pressure gradient between the atria and ventricles which thus impairs the rapid phase of early diastolic filling.
  • aging
    • increased collagen cross-linking, increased smooth muscle content, and loss of elastic fibers due to aging results in decreased ventricular compliance, increasing susceptibility to diastolic failure.

diagnosis of diastolic failure

  • generally requires 3 features:
    • symptoms and signs of cardiac failure (although these are rather non-specific features)
    • the presence of normal or mildly abnormal left ventricular systolic function (ejection fraction of greater than 45 percent)
      • HOWEVER, the presence of systolic failure does not exclude possible diastolic failure but does make it harder to definitively diagnose
    • evidence of abnormal left ventricular relaxation, filling, diastolic distensibility, or diastolic stiffness
      • on echocardiography, this may be suggested by either:
        • prolonged tau:
          • the time constant of LV pressure decay during isovolumetric relaxation which is a measure of LV stiffness
        • E-to-A wave ratio:
          • the ratio of peak velocities of blood flow during early diastolic filling (E wave) and atrial contraction (A wave) which is normally ~1.5.
          • the ratio falls to less than 1.0 in early diastolic dysfunction as stiffer heart relaxes more slowly.
          • As diastolic function worsens and left ventricular diastolic pressure rises, left ventricular diastolic filling occurs primarily during early diastole, because the left ventricular pressure at end-diastole is so high that atrial contraction contributes less to left ventricular filling than normal. This results in a rise in the E-to-A wave ratio which may rise higher than 2.0. This “restrictive pattern” confers a poor prognosis.
          • The E- and A-wave velocities are affected by blood volume and mitral valve anatomy and function. Furthermore, these wave velocities are less useful in the setting of atrial fibrillation.
        • E-to-A wave ratio > 2
      • on coronary angiography

Rx principles of diastolic failure

  • normalise blood pressure (to less than 130/85mmHg) to promote regression of LVH
  • avoid tachycardia - eg. low dosage beta blockers
  • reduce ischaemia
  • Rx symptoms - consider diuretics, ACEIs, digoxin
  • consider dihydropyridine calcium channel blockers with care
    • The long-acting dihydropyridine class of calcium channel blockers is safe for use in patients with systolic heart failure, but nondihydropyridine agents should be avoided.

References

ccf.txt · Last modified: 2016/08/08 09:24 by gary1