Arrhythmia

An abnormal heart rhythm, also called dysrhythmia

Bifurcate

Divide into 2 branches or forks

Depolarization (Chemical
contraction)

Opening and closing of potassium channels leads to a change in the polarity of the
cardiac cells causing the muscles to contract.

Intrinsic

Occurs naturally

Occlusion

Blockage of the vessel opening

Perfuse

Supply with blood

Pericardium

Two layer, protective sac surrounding heart. Filled w/ fluid to prevent friction.

Vocabulary

3 Heart Layers

Epicardium (outer layer)

●Made of connective tissue and forms pericardium

○Pericardium consists of visceral layer that covers heart and
outer parietal layer that connects to diaphragm/mediastinum

Myocardium (middle layer)

❖Striated muscle that contracts

Endocardium (Inner Layer)

❏Smooth surface forms valves

❏Protects inner layer

❏Promotes perfusion

Diastole (Relax)

➢

Coronary vessels perfused

Systole (Squeeze)

●Semilunar valves close

●Chambers fill

●Coronary vessels compressed

●Support valves

●Prevent backflow

●Also called heart strings

●Mitral = Bicuspid

●Aortic/pulmonary = semilunar

Chordae Tendineae

Nothing Changed but the name

Valveuable Information

★

Perfuse cardiac tissue

★

Branch off the aorta

★

Right/left coronary artery

Coronary Arteries

Perfuses

◆

Right atrium/ventricle

◆

Part of left atrium

◆

Inferior wall of left ventricle

◆

SA node

Right Coronary Artery

(RCA)

Right side dominance

Sometimes the posterior descending
artery arises from the distal region of the
RCA

Gen. Info.

➔

Perfuses myocardium

➔

Bifurcates into:
◆

Left circumflex
artery (LCx)

◆

Left anterior
descending
artery (LAD)

LCx

Perfuses posterolateral

aspect of the left ventricle

LAD

➔

Supplies anterior wall
of LV

➔

Occlusion leads to
arrhythmia and death

Left Main Coronary Artery (LMCA)

Collateral Circulation

●Small coronary arteries grow and connect to
other arteries due to decreased perfusion

●Patients w/ heart disease may not show
symptoms until late disease stage due to
oxygen compensation

Electrophysiology

Electrical pathway of the heart

Electrical Pathway Gen. Info

Normal Impulses

Generated by Sinoatrial (SA)
node and continue toward

apex and terminate at

purkinje fibers

Ectopic Beats

Automaticity

Ability of cardiac cells to

generate electrical

activity

Systole
Occasionally cells in the

atrium/ventricle will
become irritated and

initiate electrical impulse

outside the pathway

Electrical impulses cause

the myocardium to

depolarize and contract

Internodal
Pathway

➢

Primary pacemaker of
the heart

➢

Intrinsic rate 60-100

➢

Depolarizes right
atrium first

➢

Connect SA node to
AV node

➢

Three pathways

○Anterior

○Medial

○Posterior

➢

Bachmann's Bundle
(interatrial tract)

○Pathway
connecting RA
and LA

Sinoatrial (SA) Node & Internodal Pathways

​SA Node

AV Node

❖

Also known as AV
bundle

❖

Located in the
interventricular
septum

❖

Trasmits
down/through
interventricular
septum and beneath
endocardium

❖

Backup pacemaker

❖

Intrinsic rate 40-60

❖

Pauses impulse to fill
atria

❖

Perfused by
atrioventricular node
artery

Atrioventricular (AV) Node & Bundle of His

​Bundle of His

Left Bundle
Branch (LBB)

Right Bundle
Branch (RBB)

●From Bundle of His to
right ventricle

●Depolarizes RV

●Perfused by LAD

●Located
interventricular
septum

●Depolarizes LV

●Left anterior fascicle

○Runs anterior
surface of heart

●Left posterior fascicle

○Runs from
septum to
purkinje fibers
on posterior LV

Bundle Branches

Purkinje Fibers

❏

Junctional conduction
pathway

❏

Depolarizes ventricles

❏

Become pacemaker if
SA and AV node fail

❏

Intrinsic rate 20-40

Purkinje Fibers

Conduction System Overview

1. Sinoatrial node

2. Atrioventricular Node

3. Bundle of His

4. Right/left bundle

branches

5. Purkinje Fibers