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15 Cards in this Set

  • Front
  • Back
Describe the conduction system of the heart.
SA Node: RACE, intrinsic pacemaker, 60-100bpm.

Intraatrial Pathway:EC

Internodal Pathway: EC

AV Node: RACE, 40-60bpm

Bundle of His: EC, augments voltage, starts ventricular contraction.

L + R Bundle Branch: CE

Purkinje Fibers: RACE, 10-40 bpm
Properties of the RCA
Feeds 60% pf SA node.
90% of AV node.

Feeds entire R Ventricular wall.
Dominant Arteries
RCA feeds the biggest part of the back of the heart in 80-85% of the population.
Properties of the LCA
LCA splits:
L Anterior Descending:
Feeds 40% of SA node
10% of AV node

Feeds entire L Anterior Ventricular wall.

Cirumflex Artery: Feeds L Atria. Feeds the remainder of the back of the heart (dominant in 15-20%)

Feeds posterior branch of L bundle.
Three components of Cardiac Output
Preload: How much blood comes into the heart.

Afterload: Blood that comes out of the heart to feed the body.

Contractility: The ability of the heart ot contract and empty.
S/S of low cardiac output.
Systolic BP of less than 90.

Cold & Clammy skin.

Change in level of consciousness.
Factors that affect preload
Blood volume

Venous tone

Venous return

Atrial contraction
Factors that affect afterload
Fluid volume


Vascular disease

Pulmonary disease
Factors that affect contractility

Scar tissue

Acute MI

4 Cardiac effects
Inotrope: effecting contractile force

Chronotrope: effecting HR

Dromotrope: effecting the speed of conduction of electrical impulses

Bathmotrope: effects irritability
Describe the electrophysiology of the cell
(Sodium Pump)
Polarization: K+ in the cell, Ca+ on the membrane, Na+ outside the cell. Resting state.

Deporization: By action of pacemaker, Ca+ and Na+ inside cell, K+ outside.

Repolarization: Back to original state.
Leads: I, II, III
I: LA +
RA -

II: RA -
LF + (Below waist)

LF +
Leads: which ones look at what?
Lead I, AVL: upper part of L ventricle.

Lead II, III, AVF: Lower R Ventricle.

VI, VII: Septal wall

VIII, IX: Anterior wall of L Ventricle

X, XI: Lower lateral wall.
Leads: Chest
V1: 4th intercostal space, to the right of the sternum.

V2: 4th intercostal space, to the left of the sternum.

V4: 5th intercostal space in the midclavicular line.

V3: halfway between V2 & V4.

V5: anterior axillary line, level with V4.

V6: midaxillary line level with V4.
Conduction through the Heart
1. Septum depolarizes from R to L.

2. Lower 2/3 of R Ventricle.

3. L Ventricle through ventricular wall.

4. Upper 1/2 of R ventricle (goes toward shoulder).