Cardiac Rhythms and ECG Interpretation

Flashcards covering cardiac anatomy related to electrical conduction, ECG measurement rules, and various atrial and ventricular dysrhythmias.

Hypertrophy

An increase in muscle mass that create more contractile force; often occurs after an acute event such as an MI.

Acute Failure

A state where the heart is very stressed and unable to compensate, leading to increased pressure in the lung's venous blood vessels, fluid movement into interstitial spaces, and eventually pulmonary edema.

SA node

Located in the upper posterior wall of the Rt atrium, it is the Pacemaker where the initial impulse fires at $60$-$100\,bpm$.

Atrial Systole

The contraction of both atria, stimulated by the SA node impulse, which propels blood into the ventricles.

AV node

Located in the lower portion of the Rt atria, this node pauses the impulse before it travels to the bundle of HIS; it fires at $40$-$60\,bpm$.

Purkinje fibers

Fibers that conduct the impulse quickly to stimulate both ventricles to contract (ventricular systole).

Arrythmias

An irregularity or loss of rhythm.

Dysrythmias

Abnormal, disordered, or disturbed rhythm; stated as the most accurate term when discussing abnormal rhythms.

Sinus Bradycardia

A slow heart rate ($< 60\,bpm$) originating in the SA node with components of a normal cardiac cycle.

Atropine sulfate

A short-term medication used to treat symptomatic Sinus Bradycardia.

Sinus Tachycardia

A fast heart rate between $101$-$180\,bpm$ originating in the SA node, where all other cardiac cycle components are normal.

PRI (Normal Sinus Rhythm)

The PR Interval, which normally measures between $0.12$ and $0.20\,seconds$.

QRS Interval (Normal Sinus Rhythm)

The interval measuring between $0.06$ and $0.11\,seconds$.

Premature Atrial Contractions (PACS)

Occurs when the atria fire an impulse before the SA node fires, interrupting the underlying rhythm.

Atrial Flutter (A Flutter)

A rhythm where the atria contract at $250$-$350\,bpm$, characterized by a "sawtooth" or F wave pattern on an ECG.

Atrial Fibrillation

An extremely rapid and chaotic atrial rate ($350$-$600\,bpm$) with no definable P waves, resulting in an irregularly irregular rhythm.

Premature ventricular Contractions (PVC)

Impulses originating in the ventricles from an ectopic focus that cause a premature beat and a bizarre, wide QRS complex ($> 0.11\,seconds$).

Unifocal PVCs

PVCs that look the same because they originate from the same irritable area.

Multifocal PVCs

PVCs that do not look the same because they originate from several different irritable areas.

Bigeminy

A PVC occurring every other beat.

Trigeminy

A PVC occurring every third beat.

Quadrigeminy

A PVC occurring every fourth beat.

Couplet

Two PVCs occurring together.

Ventricular tachycardia

A run of three or more PVCs occuring together.