Cardiac AP Flashcards
Parts of the pericardium?
Fibrous –> Non compliant outer
Serous –> Inner, containing visceral and parietal layers and paricardial sac
S&S of pericarditis?
- Decreased cardiac compliance
2. Global ST event
Layers of heart?
- Epicardium
- Myocardium
- Endocardium
What type of blood goes in the right atrium from where?
Deoxygenated blood from the superior, inferior vena cava and coronary arteries
What type of blood goes into the left atrium and from where?
Oxygenated blood via the 4 pulmonary veins
What do murmur sounds in the heart originate from?
Turbulent blood flow in the cardiac valves
What are the properties of myocardial cells?
- Automaticity
- Excitability
- Conductivity
- Contractility
How is mean arterial pressure calculated?
MAP = Systolic BP + (2xDiastolic BP) // 3
When are the coronary arteries best perfused?
During diastole
What does the R coronary artery perfuse?
Arises from aorta, perfuses RA, RV, Posterior wall of RV to intraventricular septum, AV node, SA node
What does L coronary artery perfuse?
Arises from aorta, perfuses L Main Stem including L anterior descending artery and circumflex artery. Perfuses anterior LV and part of RV
What happens if R Coronary artery is blocked?
RV failure, bradycardia, heart block
What happens if L main stem is blocked?
Conduction issues, LV failure, “widowmaker” lethal
What happens if circumflex artery is blocked?
L free wall damage and ventricular aneurysm
What do the coronary veins do and which is the main one?
Venous drainage of myocardium emptying into the RA. Coronary Sinus drains the majority
Where are atherosclerotic plaques commonly found?
- Bifurcations
2. Small narrow vessels
What is a percutaneous coronary intervention (PCI)
Done by interventionist, following angiogram cardiac catheterization is done via femoral or radial artery. Stent is inserted to open vessels
What is a coronary artery bypass graft (CABG)
Done by cardiac surgeon, chest is opened and an artery/vein is “harvested” to be stitched onto aorta and other end of heart bypassing the blockage
What are the common sites for CVC insertion?
- Internal jugular (most common)
- External jugular
- Brachial
- Femoral (not ideal)
What is the firing rate of the various pacemakers?
- SA node (60-100)
- AV node (40-60)
- Ventricles (<40)
What is the cardiac conduction pathway?
- Impulse arises from SA node in RA
- Transmitted through atrial internodal tracts
- AV node at floor of RA conducts with delay to provide atrial kick
- Bundle of His divides into LBB and RBB
- Purkinje fibers carry impulse throughout ventricles
What happens during ventricular diastole?
- Blood enters passively into RA from inferior, superior vena cava
- Blood enters passively into LA from pulmonary veins
- AV valves open and ventricles fill passively (70%)
- Both atria “kick” filling remaining 30%
What happens during ventricular systole?
- Ventricles contract, RV into pulmonary artery, LV into aorta
- AV valves close
- Semilunar valves open
- Backflow of blood closes semilunar valves
What is the normal ejection fracture?
60-80% (healthy ventricle ejects 2/3 of volume)
What do the heart sounds represent?
S1 –> Tricuspid + mitral valves closing
S2 –> Semilunar valves closing
What is cardiac output defined as?
Amount of blood pumped out in L/min (usually 5-8)
CO = Stroke volume x HR
What is stroke volume and what influences it?
Amount of blood pumped out per beat. Influenced by:
- Preload
- Afterload
- Contractility
What law describes preload concept?
Frank Starling’s law: Increased stretch = increased force of contraction
What is afterload and what can affect it?
Resistance met by ventricles during systole. Affected by:
- Stenosis
- HTN
- Regurgitation
- Blood viscosity
- Vasoconstriction, dilation
Why is tachycardia bad?
Is the compensatory mechanism (SNS) for decreased CO. Tachy will decrease ventricular filling time, decreasing preload and CO, decrease coronary artery perfusion leading to myocardial ischemia
What are cardiac baroreceptors?
Found in carotid sinus and aortic arch, they regulate BP using PSNS / SNS by vasoconstriction or vasodilation
What does Atrial Natriueretic Peptide and Brain Natriueretic Peptide do?
Released when sensing increased fluid volume. Starts vasodilation and natural diuresis by not reabsorbing Na+ in the kidneys resulting in H20 following
