Lecture 13 - Heart Sounds & Murmurs Flashcards
describe S1 sounds
- “lub”
- closure of mitral and tricuspid valves
describe S2 sounds
- “dub”
- closure of aortic and pulmonic valves
Split S1 sound
- asynchronous AV valve closure
- can be normal in larger dogs
- bundle branch block, VPCs, dyssynchrony of ventricle contraction
Split S2 sound
- async closure of aortic/pulmonic valves
- inspiration increases venous return and ejection time
- prolonged RV ejection (PS, PH) or LV ejection (AS, SHTN)
S3 Gallops
a. what is it?
b. when is it heard?
c. is it always abnormal?
- low-pitched during diastole
- passive blood-filling ventricle and impacting on wall
- abnormal in small animals, can be DCM
- sometimes normal in horses
S4 Gallops
a. what is it?
b. when is it heard?
c. is it always abnormal?
- low-pitched during diastole
- atrial contraction (“kick”) due to thickened left ventricle
- abnormal in small animals (HCM)
T/F: both S3 and S4 sounds would be heard in early diastole
FALSE - only S3, S4 in late diastole
mid-systolic click
- extra “click” in systole between S1 and S2
- MV prolapse (tense chordae tendinae)
when would heart sounds be increased?
hyperdynamic state (fever, anemia, pimobendan use)
when would heart sounds be decreased?
myocardial dysfunction
when would heart sounds be muffled?
presence of effusion
T/F: laminar flow occurs up to a critical velocity and then becomes turbulent flow
TRUE
turbulent flow occurs because of what 2 things
- change in direction
- increase in velocity
define heart murmur
prolonged audible vibration of turbulent flow in the heart
what are the 4 general causes of heart murmurs
- high velocity
- decreased blood viscosity (anemia)
- large stroke volume
- turbulence in flow
murmurs are described by what
- location
- timing and duration (within cardiac cycle)
- intensity
- frequency or pitch
the point of maximal intensity in cats is
sternal or parasternal
what is the PMI for the mitral valve
5th intercostal space, left side, elbow height
what is the PMI for the aortic valve
4th intercostal space, left side, craniodorsal to mitral
what is the PMI for the pulmonic valve
3rd intercostal space, left side, armpit
what is the PMI for the tricuspid valve
5th intercostal space; right side, point of elbow
systolic murmur
between S1 and S2
occurs during ventricular ejection when AV valves should be closed
diastolic murmur
occurs when ventricles are filling/relaxing and aortic/pulmonic valves should be closed
continuous murmur
heard throughout systole and diastole
grade 1 murmur
soft, heard with difficulty, one location (focal)
grade 2 murmur
soft, heard in one location but does not radiate from PMI (focal), readily heard
grade 3 murmur
moderately loud murmur readily heard and radiates slightly, regional
grade 4 murmur
loud murmur that radiates widely and can be heard on both sides of thorax
grade 5 murmur
very loud associated with palpable precordial thrill felt on one side of thorax
grade 6 murmur
heard with stethoscope lifted off thorax wall, radiates
crescendo
gradually increases to peak intensity
decrescendo
gradually tapers from initial peak
Diamond
builds to peak and tapers off
plateau
equal in intensity throughout
what is responsible for timing and opening of valves
pressure gradients
stenosis
valves do not open fully/properly due to the narrowing of path, so the heart works harder
regurgitation
valves do not close properly and resulting in leaky valves where blood flows backward
if _____ and _____ are increased, cardiac work increases
volume; pressure
eccentric hypertrophy
increased volume from valve insufficiency
concentric hypertrophy
increased pressure from stenosis
eccentric hypertrophy leads to ____ of chamber and concentric hypertrophy leads to ____ of walls
dilation; thickening
T/F: diastolic pressure is increased in concentric hypertrophy
FALSE
what type of murmur decreases stroke volume
mitral valve regurgitation
T/F: mitral valve regurgitation is a common left apical systolic murmur in dogs
TRUE
systolic murmur
AV valves
diastolic murmur
aortic and pulmonic valves
shunt
abnormal mixing of blood in heart or great vessels
what 3 conditions cause volume overload to the left side of the heart
- patent ductus arteriosus
- ventricular septal defect
- atrial septal defect
T/F: PDA is a continuous murmur
TRUE
T/F: in a ventricular septal defect, where flow is left to right, a patient may be cyanotic
FALSE - blood will be oxygenated
an increase in pulmonary circulation increases what two things?
- venous return
- left ventricle volume
what is a rare defect in animals that allows the mixing of blood from the atria
atrial septal defect
