Cardiac Assessment Flashcards
3 Layers of the Heart
Endocardium - inner
Myocardium - muscle itself
Epicardium - outer layer
Pericardium is
Sac around the heart
2 Layers of the Pericardium
Visceral = inner Parietal = outer
Pericardial fluid purpose
Lubricate pericardial space
Prevent friction as the heart contracts
Coronary arteries
- Left coronary artery
2. Right Coronary artery
2 branches of the LCA and what do they supply
- Left Anterior Descending (LAD)
- Left Circumflex (Main) Artery (LCA)
Both supply LA, LV, interventricular septum, portion of RV
What does the RCA supply?
RA, RV, and part of the wall of LV
What is the widow maker?
LCA = 100% blocked
LCA blockage = ischemia to left side of heart = muscle death = no CO = death
Conduction though the heart
SA Node -> Atria -> AV Node -> Bundle of His -> Bundle Branches -> Purkinje Fibers (ventricular contraction)
How does cardiac impulse control heart rate?
Further down the impulse starts, the slower the heart rate
What is the formula for Cardiac Output (CO)
CO = Stroke volume (SV) x Heart Rate (HR)
What is normal cardiac output?
4-8 L per minute
Cardiac Index is
CO divided by body surface area (BSA)
Normal Cardiac Index (CI) =
2.5 - 4 L/min
Factors that affect cardiac output
Starling’s law
Preload
Contractility
After load
Starling’s law
More the heart fibers are stretched the greater the force of contraction
Preload
Volume issue; amount of blood in th ventricles at the end of diastole
Decreased preload can indicate?
Dehydration
Increased preload can indicate?
Hypertension or Heart failure
Contractility of the heart is
How effectively does it contract
Afterload is
Pressure/Resistance issue; resistance agains what the left ventricle must pump to the body
Regulation of the cardiovascular system is controlled by
Autonomic Nervous System; more importantly the sympathetic nervous system (SNS)
What is the function of the sympathetic nervous system
Increase HR and atrial and ventricular contraction
Alpha andrenergic receptors
Leads to vasoconstriction