heart failure
heart failure is either
a filling problem (poor compliance or lack of space to fill)
OR
-a contracting problem (poor contractility)
HF stats
Etiology: who gets HF?
The goal is to…
Improve cardiac output
cardiac output
the amount of blood ejected out of the ventricles each minute
cardiac index
-CO adjusted for body size
-CI=CO X BSA
BSA=body surface area. -calculated with height and weight
[height(cm) X weight (kg)] / 3600^1/2
stroke volume
the amount of blood ejected from the ventricles with each ventricular systole (contraction)
CO=HR*SV
preload
-measurement of volume
-the amount of blood in the heart at the end diastole
-increased with volume replacement (IV fluids, etc)
-decreased by blood loss and diuretics
lower preload= lower CO
-atria
afterload
contractility
Frank Starlings law (or curs)
-as you increase preload, contractility will improve, to a point. too much preoad can overstretch the heart and weaken the cardiac muscle causing worsening contractility
hemodynamics principle review
CO=HR*SV
preload dumps blood into heart
-contractility forces the blood out of the heart
-afterload is the resistance the heart must work against
What causes the heart to fail?
1) impaired myocardial function: CAD, rheumatic fever, endocarditis, cardiomyopathy
2) increased cardiac workload: hypertension, valve disorders, anemia, congenital heart defects
3) non-cardiac conditions: volume overload, hyperthyroidism, massive PE
compensatory mechanisms in HF
HF affects every body system
The kidneys role in HF
1- decreased renal perfusion ( low CO)
2- angiotensin 2 and aldosterone are released
3- causes increased anti-diuretic hormone (ADH)
4- ADH causes kidneys to absorb more water
5-this combo of increased sodium & water leads to a further increased preload
6- the weak heart cannot handle the excess in fluid (preload) and congestion worsens, heart becomes more dilated and CO drops even more
systolic HF
diastolic HF
left sided HF
- the fluid back up reaches the pumonary bed and causes pulmonary edema
S/S of left sided HF
S/S of left sided HF cont
pulmonary edema
assessment findings of pulmonary edema