Heller Ch. 3 Flashcards
P wave
Atrial depolarization
QRS complex
Ventricular depolarization
T wave
Ventricular repolarization
Aortic pressure
Diastole: 80mmHg
Systole: 120mmHg
Left ventricular volume
End-Systole: 60mL
End-Diastole: 120mL
Right atrial pressure
A wave: contraction
C wave: tricuspid valve ballooning
V wave: Isovolumetric filling
Pulmonary artery pressure
Diastole: 10mmHg
Systole: 25mmHg
Valve changes
Valve placement is determined by pressure
Sounds
Caused by valve closure (AV valves or aortic/pulmonic)
Incisura (dicrotic notch)
Dip in aortic pressure caused by a small volume of blood filling the aortic leaflets as the valve closes
S1 sound
Closure of AV valves
Immediately after QRS complex
Heard best at the apex
S2 sound
Closure of aortic/pulmonic valves
At the end of T wave
Physiological splitting of the second heart sound–the pulmonic valve will lag behind the aortic (particularly with inspiration)
S3 sound
Does NOT usually happen
Happens shortly after S2…called ventricular gallop rhythm
During rapid passive ventricular filling
Can be normal in children…otherwise indicates left ventricle failure
S4 sound
Does NOT usually happen
Happens shortly before S1…called atrial gallop rhythm
Associated with atrial contraction and rapid active filling of the ventricle
Indicates an increased ventricular diastolic stiffness…can occur with several cardiac disease states
Left ventricle cycle
Mitral valve opens--> Diastolic filling (passive stretch)--> Reaches end-diastolic volume (length)--> Isovolumetric contraction (Isometric tension development)--> Aortic valve opens--> Ejection (shortening)--> Reaches end-systolic volume (length)--> Isovolumetric relaxation (Isometric relaxation)
Cardiac index
Cardiac output corrected for the individual’s size…more by surface area than weight
Larger end-diastolic volume
Larger stroke volume
Peak isometric tension initially increases slower than resting tension
Larger afterload (HTN or aortic valve obstruction)
Smaller stroke volume
There is less shortening
Myocardial substrate use during basal metabolism
25%
Myocardial substrate use during isovolumetric contraction
50%
Depends on afterload
Related more to isometric wall tension development than to intraventricular pressure development
Stroke work
Pressure x volume
Pressure work adds up more than volume work
Heart Rates effect on substrate consumption
One of most important determinants
It is better energetically to have a lower HR and an higher SV than the opposite
Lusitropic
Relaxation rate
5 effects of NE
Positive chronotropic effect (increases i[f])
Decreases duration (earlier i[K])
Positive dromotropic effect (alters conductivity of gap-junctions)
Positive inotropic effect (activates i[Ca++])
Positive lusitropic effect (increases SR reuptake of Ca++)
