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Heart Failure
Dr. Meg-angela Christi M. Amores
• The term "cardiac failure" means simply
failure of the heart to pump enough blood to
satisfy the needs of the body
Heart Failure
• can result from any heart condition that
reduces the ability of the heart to pump blood
• Usually due to: decreased contractility of the
myocardium resulting from diminished
coronary blood flow
– Also caused by: damaged heart valves, external
pressure around the heart, vitamin B deficiency,
primary cardiac muscle disease
Dynamics of the Circulation in Cardiac
Failure
• Acute Effects of Moderate Cardiac Failure
– If heart is severely damaged, pumping ability of
the heart is immediately depressed
– 2 main effects:
1. Reduced cardiac output
2. damming of blood in the veins, resulting in
increased venous pressure
progressive changes in heart pumping
effectiveness after MI
• Top curve: normal Cardiac output
• Point A is normal operating point
• After heart is damaged, cardiac
output curve immediately lowered
• After seconds, new circulatory state
is established (point B)
• Only sustain for a few hours
• Associated with fainting
Compensation by Nervous Reflexes
• When cardiac output falls precariously low,
many circulatory reflexes become activated
• Best known: BARORECEPTOR reflex
• activated by diminished arterial pressure
– Other reflexes: chemoreceptor reflex, the central
nervous system ischemic response, and even
reflexes that originate in the damaged heart
• the heart, one way or another, becomes a
stronger pump
progressive changes in heart pumping
effectiveness after MI
• new circulatory state is depicted by
point C
• Showing a cardiac output of 4.2
L/min and a right atrial pressure of 5
mm Hg
• With compensation
Compensation by Nervous Reflexes
• sympathetic reflexes become maximally
developed in about 30 seconds
Compensation by Fluid Retention
• After the first few minutes of an acute heart
attack, prolonged semi-chronic state begins:
1. retention of fluid by the kidneys
2. Varying degrees of recovery of the heart itself
over a period of weeks to months
• Renal Retention: no URINE output, until the
cardiac output and arterial pressure rise
• Thought to be detrimental
Compensation by Fluid Retention
• moderate increase in body fluid and blood
volume is an important factor in helping to
compensate
1. increases the mean systemic filling pressure
• increases the pressure gradient for causing venous flow
of blood toward the heart
2. it distends the veins
• reduces the venous resistance
• Excess fluid retention – no longer beneficial
Detrimental Effects of severe fluid
retention
• (1) overstretching of the heart, thus
weakening the heart still more
• (2) filtration of fluid into the lungs, causing
pulmonary edema and consequent
deoxygenation of the blood
• (3) development of extensive edema in most
parts of the body
progressive changes in heart pumping
effectiveness after MI
• After partial recovery, considerable
fluid has been retained
• state of the circulation is now
changed from point C to point D
• normal cardiac output of 5 L/min
but right atrial pressure increased to
6 mm Hg
SUMMARY
• “Compensated Heart Failure”
• (1) the instantaneous effect of the cardiac damage
• (2) compensation by the sympathetic nervous
system, which occurs mainly within the first 30
seconds to 1 minute
• (3) chronic compensations resulting from partial
heart recovery and renal retention of fluid
Compensated Heart Failure
• maximum pumping ability of the
partly recovered heart is still half
(LIME GREEN LINE)
• increase in right atrial pressure can
maintain the cardiac output at a
normal level
• Thus many people, especially older
people, have normal resting cardiac
outputs but ELEVATED BP
Decompensated Heart Failure
• heart becomes severely damaged
• no amount of compensation, either by
sympathetic nervous reflexes or by fluid
retention can make the excessively weakened
heart pump a normal cardiac output
• Treated by: 1) strengthening the heart , (2)
administering diuretic drugs to increase kidney
excretion
Unilateral Left Heart Failure
• left side of the heart fails,
blood continues to be
pumped into the lungs ,
whereas it is not pumped
adequately out of the
lungs by the left heart
• pulmonary vascular
congestion and
pulmonary edema
• can cause death by suffocation
in 20 to 30 minutes
Cardiogenic shock
• heart becomes incapable of contracting with
sufficient force to pump enough blood into
the peripheral arterial tree
• always occurs when more than 40 per cent of
the left ventricle is infarcted
• death occurs in about 85 per cent of patients
Edema in Heart Failure
• Acute Heart failure does not
cause EDEMA
• Long-term Fluid retention by
kidneys cause peripheral edema
• 3 causes:
1. Decreased glomerular filtration
2. Activatin of renin-angiotensin
system and increased
reabsorption of water and salt
3. Increased aldosterone secretion