Cardiac special populations Flashcards
How much oxygen does the myocardium consume at rest?
70%
The heart ____ ____ meaningfully increase its extraction ratio when oxygen demand increase
The heart can not meaningfully increase its extraction ratio when oxygen demand increase
What causes decreased oxygen delivery
Decreased Coronary Flow
Tachycardia
Decreased aortic pressure
Decreased vessel diameter
(spasm or hypocapnia)
Increased LVEDP
Decreased CaO2
Hypoxemia
Anemia
Decreased Oxygen Extraction
Left shift of HGB dissociation
curve (decreased P50)
Decreased capillary
distention
What causes increased oxygen demand?
Tachycardia
Hypertension
SNS Stimulation
Increased Wall Tension
Increased LVEDV
Increased Afterload
Increased Contractility
What is the hallmark of systolic heart failure (eccentric hypertrophy)?
decreased EF with and increased EDV
Since the heart can’tsqueeze well, a greater amount of blood remains in the ventricle after each contraction
What happens to chamber size with systolic HF?
Chamber size increases in an attempt to preserve stroke volume
Becomes more spherical shaped
Volume overload causes eccentric hypertrophy
Degree of systolic heart failure by EF classification
Calculation: SV/EDV
Normal: >55%
Mild: 45-54%
Moderate: 30-44%
Severe: <30%
APEX
Normal: >50%
Mild: 41-49%
Moderate: 36-40%
Severe: <24%
What causes systolic heart failure?
all basically from an increase in volume
CAD / myocardial Ischemia
***Volume Overload ( d/t Valve insufficiency)
Dilated cardiomyopathy
How do you treat systolic HF?
Fast, Full, Forward (reduce afterload)
-similar to regurg-
If EF is low, higher HR is needed to preserve C.O.
What is the hallmark of diastolic HF?
symptomatic HF with preserved EF
Diastolic failure occurs when the heart is unable to relax and accept incoming volume
What happens to the myocardium with diastolic (concentric) heart failure?
Chronic pressure overload leads causes the myocardium to thicken
How do you treat diastolic heart failure?
Slow, Full, Constricted
-similar to stenotic lesions-
What is crucial in treating diastolic heart failure?
The LV with concentric hypertrophy is prone to ischemia, Maintenace of a high MAP and slow normal HR is crucial. Hypotension should be treated promptly with phenylephrine!
What is the most common cause of right heart failure?
Most common cause of right heart failure is left heart failure
Also caused by pulmonary HTN and right sided MI
Anything that increases pulmonary vascular resistance can impair RV function
Hypoxemia, hypercarbia, Acidosis
What is the main goal of treatment for right heart failure?
to improve contractility while reducing right heart afterload
Inotropes and decreased PVR
What meds can reverse remodeling?
Ace Inhibitors/ aldosterone inhibitors
Stages of hypertension
Normal 120/80
Pre-hypertension 120-129/80
Stage 1 hypertension 130-139/80-90
Stage 2 hypertension 140/90
Hypertensive crisis 180/120
Primary – no identifiable cause (95% of cases)
Secondary – identifiable cause (5% of cases)
Coarctation of the aorta, Renovascular disease, Cushing syndrome, Conn’s syndrome, Pheochromocytoma, Pregnancy-induced HTN