CV Part 3 Flashcards
What is reentry?
Phenomenon of opportunity
Form self sustained electrical current
Multiple depol in multiple regions of myocardium
What is the ventricular rhythm in A fib?
Irregularly irregular (AV node fluctuates in conduction frequency)
When is the vulnerable period?
Down slope of T wave (end of repol)
What happens during the vulnerable period?
Myocytes vary in excitability
Some are easily re-stimulated → reentry possible
What’s an infarct?
Area of necrosis due to sudden blood supply loss
Where’s the most common location for an MI?
LV → high muscle mass and O2 demand
Changes in ECG for MI (3)
Inverted T wave
ST segment elevation
New Q wave
What does new Q waves indicate?
Irreversible myocardial death
What does an inverted T wave represent?
Ischemia
** not diagnostic for MIs **
What does the ST segment represent?
Myocardial injury has occurred
Due to difference between RMPs of the healthy vs ischemic myocardium
Inferior and posterior regions are heart are supplied by
Right coronary artery
If inferior myocardium is affected by occlusion in the ________, then electrical changes would be seen in _______ leads such as _______
Right coronary artery
Inferior
2, 3, aVF
If posterior myocardium is affected by occlusion in _______, then we would check lead ______
Right coronary artery
N/A → posterior does not have a dedicated lead!
Lateral regions of the heart are supplied by the
Left circumflex artery
If left lateral myocardium is affected by occlusion in _______, then we would check leads ________
Left circumflex artery
1, aVL, V5, V6
Anterior regions of the heart is supplied by
Left anterior descending artery
If anterior myocardium is affected by occlusion in ______, then we would check ______
Left anterior descending anterior Precordial leads (V1-V6)
S1
Onset of ventricular systole
Closing AV valves
Lub
S2
Closing semilunar valves
Split into aortic and pulmonic valve component
Dub
Physiologic splitting
Aortic valve component and Pulmonic valve component during S2
Can tell difference during inspiration
Physiologic splitting occurs due to
Decreased thoracic pressure that’s generated during inspiration
Which valve closes after the other under normal inspiration?
Pulmonic valve closes after Aortic valve
What is widened splitting?
What does this mean?
3 Examples
Increase the delay between A2 and P2
Delay is pulmonic valve closing → prolonging cardiac cycle in right heart
Right BBB, Pulmonary Hypertension, Pulmonary Stenosis
What is paradoxical splitting?
What does this mean?
2 Examples
P2 occurs before A2
Aortic valve closes after pulmonic valve → delay aortic valve closure
Aortic Stenosis, Left BBB
S3
Occurs after S2
Heard in elevated left heart filling pressures of adults sometimes
S4
Heard in late diastole
Heard if PT has left ventricular hypertrophy
Heart sounds are generated by
Valves closing and atrioventricular blood turbulence due to AV pressure
Stenosis
Constriction of narrowing
Regurgitation
Pressure induced backwash through leaky valve
Aortic valve stenosis
LVP»_space;> aortic pressure
Can result in LVH
Murmur intensifies at mid-systole
Pulmonic valve stenosis
RVP»_space;> pulmonary arterial pressure
Cause RVH
Intensity increases during inspiration
Mitral stenosis
Left atrial hypertrophy
Increased amplitude and duration of leads 1 and V1
High pitched opening snap and then diastolic rumble
Mitral regurgitation
Blood leaks back into LA → works harder against higher pressures
Notched P wave in ECG
Tricuspid regurgitation
Reflux of blood during RV systole → increases jugular venous pressure
Aortic valve regurgitation
LV volume and pressure increase
LV dilatation and hypertrophy
Acute changes in ________ can induce changes in BP
Intravascular volume
Hypovolemia
Low plasma volume
Hypervolemia
Elevated plasma volume
High pressure baroreceptors are located in
Aortic arch
Carotid sinus
Low pressure baroreceptors are found in
RA/vena cava
LA/pulmonary vein
Low pressure baroreceptors are sensitive to
Pressure induced stench
Firing rate changes during atrial systole and diastole
Chemoceptors are located in
Carotid sinus
Aortic arch
Chemoceptors sense
Decreases in PO2 (partial pressure)
Elevated PCO2
Decreased pH
Chemoceptors are especially sensitive to small changes in
PCO2
Baroreceptors and Chemoceptors are designed to correct ________ changes but they can become _______ over time
Acute
Desensitized
