Table of Contents
congestive cardiac failure
- NB. age > 65 with primary Dx of CCF are admitted to cardio-geriatric unit at Western Hospital if present to Western Health
- 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:
- paroxysmal nocturnal dyspnea
- weight loss of 4.5 kg in 5 days in response to treatment
- neck vein distention
- 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
- 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
- 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
- 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
- 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:
- 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)
- 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 is the most common cause and causes LV hypertrophy and increased connective tissue content, both pf which decrease cardiac compliance.
- Hypoxia inhibits the dissociation of myosin-actin crossbridges during muscle relaxation as this requires active transport of calcium ions into the sarcoplasmic reticulum.
- 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.
- 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.
- 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.
ccf.txt · Last modified: 2016/08/08 09:24 by 127.0.0.1