the inability of the heart to pump sufficient blood and oxygen to meet the metabolic needs of the body OR to do so at an abnormally Ý filling pressure (i.e. during diastole)
Congestive Heart Failure
= ß CO
Definition
: NOT a specific diagnosis but the final common pathway for a variety of pathologic conditions:
Heart muscle abnormality (most common)
Primary myocardial weakness – impaired systolic function
Altered myocardial relaxation – impaired diastolic function
Valvular heart disease - stenotic or valvular insufficiency
Pericardial disease – pathology with sac around hear interferes with filling of the heart
Þ abnormally Ý filling pressures
Etiology
:
Coronary Heart Disease (blockage of the arteries – heart attack)
hypertension (associated with coronary disease)
Diabetes (leading to heart disease)
idiopathic
alcohol or other toxins
post-partum
Systolic heart failure
:Heart muscle weakness resulting in poor pumping function
Most common type (60-70%)
Heart Failure not otherwise specified is implied to be systolic heart failure.
Diastolic Heart Failure
:Abnormal diastolic relaxation leading to abnormal elevated filling pressure. Intact systolic function – "normal squeeze"
More common in the elderly and HTN
30% of cases
Epidemiology:
Prevalence – 4.5 million
Incidence – 400,000 new cases annually
#1 admission of acute care
250,000 deaths
Measurement of Systolic Function
Ejection Fraction
– the percentage of the blood ejected with each heart beat
(End diastolic volume – End systolic volume) / end diastolic volume
Normal 50-75%
Cardiac Output
- The quantity of blood ejected per minute
Equal to stroke volume x heart rate; may be normal even with a reduced EF due to ventricular dilation;
Cardiac index
– CO divided by Body Surface Area
Preload:
the stretch on myocardial fibers prior to contraction
Measured as left ventricular end diastolic volume (or pressure)
DIRECTLY related to Cardiac Output
Failing ventricle (when CO low) is LESS preload dependent than normal heart
Excess leads to congestive signs and symptoms
Afterload:
the tension against which ventricle contracts (systemic pressure)
INDIRECTLY related to cardiac output (inverse relationship)
Failing ventricle is MORE afterload dependent than the normal heart
Excess worsens cardiac performance
Pathophysiology and Symptoms
(1) LEFT
sided congestion:ß Stroke volume Þ Ý filling pressure (because of leftover blood) - Ý left ventricular end diastolic volume Þ Ý left Atrial Pressure Þ Ý Pulmonary Pressure Þ excavation of fluid into surrounding tissue (Pulmonary Edema)
SOB (exertional or at rest)
orthopnea
paroxysmal nocturnal dyspnea
Þ all symptoms relating to pulmonary edema
(2) RIGHT
sided congestion: same as above xcept resulting in extremity edema from Fluid leaking out from systemic veins
abdominal discomfort
anorexia
early satiety
extremity swelling and discomfort
(3)
Low output
fatigue
exercise intolerance
ß
mentation Þ not pumping out enough to brain (left sided symptom)
Signs
(1) Congestion signs:
Left sided signs
rales
S3 gallop
Right/both sided signs
pleural effusions
elevated JVP
hepatomegaly
ascites
dependent edema
(2) Low output:
ß
BP with narrow pulse pressure
Altered mental status
low urine output
cyanosis
Compensatory Mechanisms
Goal: Maintain adequate blood supply to the vital central organs in the face of a reduced cardiac output. How?
Cardiac:
ventricular dilitation (
Ý preload Ý CO)
ventricular hypertrophy (more mass
Ý contractility)
Peripheral:
vasoconstriction – keep blood central
Neurohormonal:
Acute:
(1)
Ý Sympathetic (epi, norepi) Þ
vasoconstriction (
Ý afterload)
tachycardia (
Ý CO)
myocardial toxicity
(2)
Ý renin-angiotension-aldosterone axis – salt, water retention, vasoconstriction
