1060 Review Flashcards
What is the inherent firing rate of the AV tissues
AV Node (Atrialventricular) 40-60 bpm
What is the inherent firing rate of the SA Node
SA (Sinoatrial)
60-100 bpm
What is the inherent firing rate of the ventricles
20-40 bpm
Where do the coronary arteries originate
The aorta (base of the heart) top of the heart
What coronary artery supplies the majority of circulation to the SA Node
(RCA) Right Coronary supplies 60% SA Node AV Node 90% as well as the Bundle of His, Right Atria and Right Ventricle posterior 1/3 of the septum
What valve prevents regurgitation of blood into the right atrium?
TRI cuspid (RI ght)
During ventricular diastole, which valves are open?
Tricuspid (on the right) aka Mitral valve
Bicuspid (on the left) aka Semilunar valve
During diastole which valves are shut?
semi lunar
List 4 layers of the heart
1) Endocardium = thin innermost layer
2) Myocardium = thick muscular layer
3) Epicardium = thin outer layer
4) Pericardium = the space that surrounds the heart with aprox 25 cc of fluid
What side of the heart is failing if you have pulmonary edema?
Left side (fluid is backing up into the lungs)
What side of the heart is failing if you have edema in the peripery
Right sided heart failure, fluid is backing up into systemic circulation
What coronary artery supplies the AV Node?
RCA Right Coronary Artery 90%
Pitting edema is caused by
right sided heart failure because the fluid is backing up into the rest of the body
What are the properties of the cardiac cell
RACCE (think racy)
Rhymiticity - keeps the beat Automaticity - initiates own impulse Conductivity - conducts impulse to cell Contractility - ability to contract* (*mechanical not seen on EKG) Excitability - ready to accept charge
What is the normal PR interval (time it takes for the impulse to travel from the SA node to Atria to AV node to common bundle)
normally 0.12 to 0.20 seconds
Atrial Repolarization is not visible on an EKG because it gets lost in the QRS
True or False
True
A wide QRS complex means
something is slowing down conduction in the ventricles
How long is the QT interval (the time it takes for the ventricles to depolarize and repolarize)
should be half of previous R to R interval or less than 0.5 seconds
what do the small squares on the EKG paper represent
a small square 1mm x 1mm = 0.04 seconds
What is a pathological Q wave?
Can indicates old/happening MI
>0.04 seconds and 1/3 the height of the QRS complex
How do you measure ST Elevation?
ST elevation is measured one small box from the J point and be > 1mm above the isoelectric line (base line)
And be present in 2 or more anatomically contiguous leads in a 12 lead EKG
How do you measure ST depression
Indicates ischemia
Segment must be >0.5mm below the isoelectric line
What does PQRST & U represent
Atrial and ventricular depolarization and repolarization are represented on the EKG as a series of waves
The PRI is measured from which point to which point?
From the beginning of the P wave to the beginning of the QRS complex
The normal PRI
0.12 - 0.20 seconds
The QRS is measured from which point to which point?
From the beginning of the Q wave to the end of the S wave
What is the normal duration for QRS?
less then 0.12 seconds (narrow) 3 small boxes
The P wave
Atrial depolarization
PR segment
Delay at the AV node
QRS complex
Ventricular depolarization
T wave
Ventricular repolarization
Isoelectric line
No electrical activity
How do you calculate heart rate (rough estimate)
count the number of R waves in a 6 second strip and multiply by 10
Heart Rate calculation (very quick)
count the number of large squares between 2 consecutive R waves and divide into 300
OR memorize this scale
1 large square 300bpm, 150bpm, 100bpm, 75bpm, 60bpm, 50bpm
One small box on EKG paper is how many seconds
0.04 seconds
Five small boxes make one big box that equals
0.20 seconds
how many seconds is 15 large boxes
3 seconds
How many large boxes is 6 seconds
30 large boxes
Name the three major coronary arteries and what area of the heart they supply
RCA SA node (60%), AV node (90%) Bundle of His, right atria and ventricle, inferior surface of the left ventricle posterior 1/3 of the septum.
LAD supplies, left ventricle anterior wall, anterior 2/3 of the septum, Bundle of His, right bundle branch.
Left Circumflex SA node (40%), AV node (10%), left ventricle lateral wall, left atrium
Where do the coronary arteries originate?
At the base of the aorta
when do the coronary arteries primarily fill with blood
when the ventricles are at rest
what is preload
pressure in the ventricles at the end of diastole
what does preload and afterload effect?
contractility (Starling’s Law)
How do inotropic drugs affect the heart
they affect the contractility of the heart muscle
What are the AV valves?
The two atrioventricular (AV) valves, the mitral valve (bicuspid valve), and the tricuspid valve, which are between the upper atria and the lower ventricles
What are the SL valves
The two semilunar (SL) valves, the aortic valve and the pulmonary valve, are in the arteries leaving the heart.
What is ACS? Acute Coronary Syndrome
So you’ve never heard of an acute coronary syndrome. But what about heart attack, or unstable angina? Those well-known conditions are both acute coronary syndromes, an umbrella term for situations where the blood supplied to the heart muscle is suddenly blocked.
What is ischemia and how is it identified on an EKG
The blood supply is being cut off - ST depression
How is injury determined on an EKG
prolonged ischemia, ST elevation
How is Infarct shown on an EKG
death of tissue, may or may not show a Q wave
How is ischemia shown on an EKG
lack of oxygenation, ST segment depression or T wave inversion
CAD Coronary artery disease
the remodeling and narrowing of the coronary arteries that supply oxygen to the heart. Plaque.
unstable angina, acute coronary syndrome, sudden cardiac death MI
diet, smoking and physical activity and genetic all factor
What are the in hospital managements of ACS
thrombolytics, angiography, angioplasty, stents, Coronary Artery Bypass Graft (CABG)
What happens during atrial systole (contraction)
Prior to systole, blood has been flowing into the ventricles through the open AV valves.
an impulse arising from the SA node results in depolarization and contraction of the atria
the P wave is due to atrial depolarization
Ventricular systole (contraction) is indicated
by the QRS complex and mechanically by the large rise and fall in ventricular pressure
what happens during ventricular diastole (relaxation)
the pressure in the left and right ventricles drops from the peak it reached in systole
when the pressure in the left ventricle drops below the pressure in the left atrium the mitral valve opens causing accumulated blood from the atrium to flow into the ventricle.
Parasympathetic stimulation stimulates what nerve
Vagus nerve
Where do the coronary arteries originate
at the base of the aorta
When do the coronary arteries get blood
during diastole
