Cardiac Labs Flashcards
What is the MOA behind S1 (1st heart sound)?
During systole, mitral valve closes d/t increased pressure in the LV –> produces the S1 sound
What is the MOA behind the ejection sound?
The pressure in the LV continues to rise and opens the aortic valve (difficult to hear)
What is the MOA behind S2 (2nd heart sound)?
As the blood leaves the LV the pressure drops below that in the aorta, aortic valve closes –> produces the S2 sound
What is the MOA behind the opening snap?
As the pressure in the LV continues to fall, it falls below the pressure of the LA and the mitral valve opens
What is the MOA behind S3?
Soon after opening of the mitral valve, rapid flow of blood flow from the LA to the LV. When rapid flow hits the wall of the LV (passive filling) it produces S3 (nml in children/ y.as; S3 gallop in older adults may be pathologic d/t change in myocardium)
What is the MOA behind S4?
LA contracts to “squeeze” the last bit of blood into the LV to produce S4 (stiff myocardium)
What is the MOA behind a split heart sound?
The R side event occurs slightly after the L side and because of this, you can occasionally hear “split heart sounds” (inc pressure in chest causes delay in pulmonic valve closure)
What is the MOA behind A2 and P2 sounds?
During inspiration S2 can be split into A2 (aortic valve) & P2 (pulmonic) normally. During expiration, sounds are combined into 1 sound (S2)
Prolonged ejection of blood from the RV which delays closure of pulmonic valve
Name 3 factors that affect stroke volume
Preload: volume (creating a pressure) that stretches the cardiac muscle prior to contraction
Afterload: vascular resistance (w/ inc BP, heart has to work harder to pump)
Muscle Contractility: ability for the cardiac muscle to contract when given a volume
What is the pulse pressure?
Difference between SBP and DBP. Small change w /each breath (can be large difference if PTX)
How would you calculate the Mean Arterial Pressure (MAP)?
Diastolic + 1/3 (pulse pressure)
When measuring arterial pressures, what would the graph look like?
Systolic phase (ejected wave) then systolic peak, then dicrotic notch; diastolic phase (reflected wave)
What does the dicrotic notch represent?
Once the aortic valve closes, it sends a pressure wave through the arterial system
Why is venous pressure than arterial pressure?
Decreased smooth muscle and vascular tone in the venous side, as well as a loss of pressure after the blood travels through the capillary bed
What are some situations that would increase venous pressure?
Decreased RV function, increased pressure within the thoracic cavity (to the R side of the heart); cardiac tamponade, CHF, etc.
How would increased venous pressure manifest itself?
Can be seen in the jugular venous column –> jugular vein distention. Can be measures from the R side with a ruler
In the venous pulsation graph, what does the a wave represent?
Atrial contraction: no valve in the SVC/ IVC so blood will go in both directions (tricuspid is open)
In the venous pulsation graph, what does the x descent represent?
Starts with atrial relaxation (filling) and continues with RV contraction (pulls the floor of the RA downwards, tricuspid closes)
Pressure in venous system is dropping as blood is leaving veins & filling the atria
In the venous pulsation graph, what does the v wave represent?
Tricuspid closure & rise in RA pressure (full)
In the venous pulsation graph, what does the y descent represent?
Opening of the tricuspid and drop in the RA pressure (emptying)
What are the normal vital sign values for: BP? MAP? CVP? Pulmonary artery occlusion pressure? Heart rate?
BP: < 140/ < 90 MAP: > 60 mmHg CVP: 8-12 mmHg Pulmonary artery occlusion pressure: 6-12 mmHg Heart rate: 60-100
What are some common signs & symptoms of the pathological heart?
- Chest pain/ discomfort
- Dyspnea, paroxysmal nocturnal dyspnea
- Orthopnea: difficulty breathing while supine
- Cyanosis
- Hyper- / Hypotension
- Lightheadedness/ Presyncope/ Syncope
- Peripheral/pulm edema, anasarca (entire body edema),
- Cardiac arrhythmias (supraventricular, AV nodal, ventricular)
- Palpitations
- EKG changes
- Echocardiographic changes: dec ejection fraction, valve abnormalities, wall motion abnml, inc. pulmonary artery pressure
- Cardiomegaly on CXR
- Asymptomatic
- Diminished/ exaggerated pulses
- Pulsus paradoxus
- Pulsus alterans
- JVD
- New onset murmurs
Define Pulsus paradoxus
A drop in systolic pressure by > 10 mmHg during inspiration d/t inc pressure in the thoracic compartment (consider PTX, cardiac tamponade d/t pressure)
Define Pulsus alterans
Pulse alternates in amplitude from beat to beat when the rhythm is nml. May suggest LV faiure
Define electric alterans
Seen on the EKG with alternating QRS amplitude: d/t inc pressure on the heart
What are the 2 types of murmurs?
Stenotic valve: narrowing of vessel itself
Insufficient valve: regurgitation
-Valvular abnormalities create turbulent flow & cause abnml heart sounds
Where/ when is aortic stenosis best heard?
Aortic area (R 2nd ICS) during systole
Where/ when is aortic regurgitation best heard?
Along L lateral border during diastole
Where/when is mitral stenosis best heard?
At the apex (L 5th ICS) during diastole
Where/when is mitral regurgitation best heard?
At the apex during diastole
Why are tricuspid/ pulmonic murmurs harder to hear?
Lower pressure system on the R side
