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47 Cards in this Set

  • Front
  • Back
What is a major determinant of mortality?
the state of the arteries
Which vessels determines blood pressure and blood flow?
arteriolar resistance arteries
What provides electrical isolation between the atria and ventricles?
cartilaginous ring in which the mitral and tricuspid valves are attached
What provides the electrical connection between the atria and ventricles?
AV node
Important feature of the AV node that allows times for mechanical filling of ventricles from atria
electrical delay
EKG: P wave represents?
atrial mass depolarization
EKG: QRS complex represents?
AV node period and ventricular mass depolarizing
EKG: T wave represents?
repolarization of the ventricle
Where is the signal for atria repolarization?
low amplitude signal buried within the QRS complex
List order of electrical activity in heart.
atrial depolarization -> AV node -> His bundle -> bundle branches -> Purkinjie fibers -> ventricular mass depolarization -> ventricular repolarization
List three therapies for disorders of the electrical system:
mechanical devices (pacemakers), ablation therapy, drug therapy
Five factors that regulate CV mechanics:
1) preload
2) afterload
3) HR
4) contractility
5) lusitropy
Passive load that determines the initial muscle length of the cardiac fibers (sarcomere length) prior to contraction.
Pre-load
What is a measure of preload in LV?
EDV
What is the most common cause of CHF?
diastolic dysfunction
Pressing on the abdomen and looking for distention in the neck veins to test for increased venous pressure
Hepatojugular reflux
Good representation of filling pressure of LV, relates closely w/ EDP.
pulmonary capillary wedge pressure (PCWP), mean pressure of the lungs
State Frank-Starling Law.
Increased venous return (LV - EDV) leads to increased SV and CO on the next heartbeat.
Systolic load against which the heart must contract
Afterload
Afterload determined by four things:
aortic valve, peripheral vascular resistance (of which resistance arterioles are the major determinants, blood properties (mass and viscosity), preload
How much tension the heart muscle will develop:
contractility
What are some conditions which will decrease contractility?
fibrosis, hypoxia/ischemia, inadequate myocardial blood flow, certain meds, acidosis
Distensibility or diastolic properties:
lusitropy
Increased LV pressure can lead to what?
pulmonary edema -> shortness of breath
Major mechanism by which most individuals increase CO in response to increased demand or excercise
Increase HR
What is a common formula for determining maximum HR?
200 - age
SV increases in excercise due to what?
increased venous return due to skeletal muscle contraction and venous constriction due to SNS
How much oxygen is extracted by muscles at rest?
95-99% Hb saturation to 75%
How much oxygen is extracted by muscles during excercise?
95% to 35% Hb saturation
What is the problem w/ CHF with respect to oxygen extraction?
Decreased CO leads to venous returns with 40% Hb saturation, therefore upon exertion, they have no oxygen in reserve
T/F: Myocardial cells are able to enhance oxygen extraction in times of demand.
False. Even at rest the myocardium fully extracts oxygen form its available blood supply.
T/F: Anerobic metabolism has very limited value for myocardial tissue.
True
List the 5 mechanisms that are used during time of exertion.
increase HR, increase SV, increase oxygen extraction, restribution of blood flow, anaerobic metabolism
What are the three effects of sympathetics on the heart?
increase HR, contractility, and AV nodal conduction (delay period btwn atria and ventricles has to be reduced)
Which dominates in most of our conscious state PS/S?
parasympathic (inhibitory)
What is the most common arrythmia?
atrial fibrillation
Left ventricle is not activated in proper sequence or over too long a period of time.
Bundle branch block
Which vessels determine myocardial blood flow?
arterioles in myocardium
Four determinants of myocardial oxygen consumption:
myocardial mass, wall stress, inotropic state, HR (MAJOR)
How does myocardium get more oxygen in times of exertion since it cannot increase its oxygen extraction ability?
inrease in coronary blood flow
When does the myocardium receive the majority of blood flow systole/diastole? Why?
Diastole, b/c myocardium contraction during systole causes constriction of arterioles penetrating myocardium increasing the resistance
Coronary blood flow is determined by what pressure gradient?
between aorta and LV pressure in diastole
What is another determinant of coronary blood flow (beside pressure gradient)?
tone of microvascular resistance vessels
How much does the diameter of a epicardial coronary vessel have to be decreased b/f causing a significant decrease in coronary blood flow?
60-70%
What kind of pressure drop is sympomatic when using fractional-flow reserve using a pressure wire?
if pressure is 85% or less compare to pressure b/f blockage
Why does tachycardia predispose to myocardial ischemia?
increases myocardial oxygen consumption and decreases myocardial oxygen supply by shortening diastole
Diastole to systole: ____ valve closes.
mitral