Term
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Definition
Low frequency sound in early diastole, 120 to 180 ms after S2
-Results from increased atrial pressure leading to increased flow rates, as seen in congestive heart failure, which is most common cause of an S3. Associated dilated cardiomyopathy with dilated ventricles also contribute to the sound.
-Less commonly, valvular regurgitation & left to right shunts may result in an S3 due to increased flow.
-May be normal phyisiological finding in pts. under 40 |
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Term
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Definition
Low frequency sound in presystolic portion of diastole
-Seen in pts. with stiffened left ventricles, resulting from conditions such as hypertension, aortic stenosis, ischemic or hypertrophic cardiomyopathy
-in pt. with mitral regurgitation, suggestive of acute onset of regurgitation due to the rupture of the chorda tendinae that anchor the valvular leaflets. |
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Term
| Three types of atrial fibers connecting the SA node to the AV node (Atrial syncytium) |
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Definition
Anterior track of Bachman
Middel track of Wenkebach
Posterior track of Thorel |
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Term
| Plateau of cardiac action potential |
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Definition
15x greater than that in skeletal muscle
-atrial muscle remains depolarized for ~0.2 seconds, ventricle muscle ~0.3 seconds
~105 mV, rises from -85 to 20 mV |
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Term
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Definition
A form of extrinsic control of cardiac pumping
-effects the heart rate |
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Term
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Definition
A form of extrinsic control of cardiac pumping
-effect on strength of cardiac contraction |
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Term
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Definition
A form of extrinsic control of cardiac pumping
-effect rate of relaxation |
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Term
| Intrinsic cardiac regulation |
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Definition
Responds to changes in volume of blood flowing into the heart.
Frank-Starling mechanism: the greater the heart is stretched during filling, the greater the force of contraction & the greater the quantity of blood pumped into the aorta |
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