The Cardiac Cycle Flashcards
First heart sound corresponds to?
closing of mitral and tricuspid valves
Which usually closes first - mitral or tricuspid?
Can we hear the difference?
Exceptions?
- Mitral first - then tricuspid
- No cant distinguish by ear
- Excpetion: RBBB where there is delayed closure of the tricuspid valve
Accentuated S1 when?
1) short PR interval- leaflets do not have time to drift back together = forced shut from a relatively wide distance
2) Mild mitral stenosis- prolonged diastolic pressure gradient exists between the left atrium and ventricle –> keeps mobile portions of the mitral leaflets farther apart than normal during diastole = since they are far apart they shut loudly when the LV contracts
Diminished S1 when?
1) lengthened PR- due to 1st degree AV block delays onset of ventricular contraction = mitral and tricuspid valves have time to float back together
2) Mitral Regurg- mitral leaflets may not come into full contact with each other as they close
3) severe mitral stenosis- leaflets are nearly fixed in position throughout the cardiac cycle = reduced movement and less sound
4) stiffened LV-hypertrophy from systemic HTN- atrial contraction means higher than normal pressure at the end of diastole = leaflets drift together more rapidly so they close over a smaller distance when ventricular contraction occurs
Physiologic splitting of S2:
-Inspirational delaying of Pulmonic valve: increase venous return on inhalation due to muscle contraction=more blood for RV to pump out compared to LV so Pulmonic valve closes AFTER the Aortic valve
Aortic valve closure and inspiration:
usually occurs slightly EARLIER in inspiration vs expieration bc the venous return to the LA decreases due to increased negative pressure of lungs in expansion/inspiration = holds more blood so less comes back to the heart
What is and Common causes of widened splitting of S2?
Audible split of A and P valve sounds during expiration and even more so during inspiration. –> DELAYED CLOSURE OF P VALVE
- RBBB
- pulmonic stenosis
What is and Common causes of Fixed splitting of S2?
Audible split of A2 and P2 valve sounds that does not change during expiration or inspiration
-atrial septal defect = chronic volume overload in right side due to high capacitance, low resistance pulmonary vacular system=>delayed back pressure that is responsible for closure of the pulmonic valve = late closure of P2 every time.
What is and common causes of Paradoxical splitting of S2:
Separation of A2 and P2 that disappears with inspirtation (abnormal delay in closing the A2 )
- LBBB - electrical impulse to left side of heart is slowed = delayed closure of A2 compared to P2. Upon inspiration P2 is delayed so the valves close around same time and splitting goes away.
- aortic stenosis-LV ejection is greatly prolonged
Opening Snap
-whats going on?
- opening of M and T is normally silent except during stenosis
- 3 sounds during inspiration A2+ P2+Opening snap (splitting of A2 and P2)
- on experation A2 and P2 one sounds + opening snap after
- opening snap timing does NOT vary with inhalation or exhalation
S3 sound
- what is it?
- normal when?
- abnormal when? Due to?
- causes?
- in early diastole (after S2)
- normal physiologic variant in patients under 40
- in patients over 40 due to LV failure (decreased ejection fraction=dilated cardiomyopathy, end-stage ischemic heart, valvular disease, severe systemic and pulmonary HTN); volume overload states (mitral regurg & ventricular septal defect)
S4 sounds
- what is it?
- normal?
- abnormal?
- causes?
“artial gallop” sounds like galloping horse
- always abnormal and especially if over 50 and audible+palpable at apex
- HTN most common
- aortic stenosis
- ischemic heart after MI
Quadruple rhythm:
patient has S4-S1-S2-S3
Summation gallop:
technique to listen to:
- a quadruple rhythm with INC HR.
- S3 from one cycle may coincide with the S4 of next cycle = single diastolic sound
- need to be really damn good
- or do a carotid sinus massage or valsalva maneuver to dec HR
Mechanism of Cardiac murmurs:
Turbulent flow due to:
1) flow across partial obstruction (aortic stenosis)
2) inc flow through normal structures (aortic systolic murmur in a high output state like anemia)
3) Ejection into a dilated chamber (aortic systolic murmur with aneurysmal dilation of the aorta)
4) Regurg flow across an incompetent valve (mitral regurg)
5) Abn shunting of blood from one vascular chamber to a lower pressure chamber (ventricular septal defect)
