Electrocardiogram (ECG) Heart Rhythms and Dysrhythmias Review

Practice flashcards covering heart block rhythms, bundle branch blocks, ventricular rhythms, and electronic pacemaker evaluation based on the lecture notes.

Sinus Rhythm (SR)

The rhythm of a normally functioning system where the current follows a normal pathway without interference.

Heart Block Rhythms

Rhythms that occur when electrical activity has difficulty traveling along the normal conduction pathway, resulting in absent or delayed ventricular depolarization.

First Degree AV Block

A delay in electrical conduction from the SA node to the AV node, characterized by a PR interval greater than $0.20$ seconds and a normal rate of $60-100$ beats per minute.

Second Degree AV Block, Mobitz I (Wenckeback)

A rhythm where the PR interval starts short and gets progressively longer until a QRS complex is dropped, often resulting from inflammation around the AV node.

Second Degree AV Block, Mobitz II

Also known as classical heart block, this condition occurs when the AV node selects which impulses to block without a specific pattern, frequently progressing to third degree AV block.

Third Degree AV Block

Also known as complete heart block (CHB), where all electrical impulses originating above the ventricles are blocked, resulting in a ventricular rate of $20-40$ beats per minute.

Branch Bundle Block Dysrhythmias (BBB)

Dysrhythmias that occur when one or both ventricular pathways are damaged, leading to a wider QRS complex duration of $0.12$ seconds and greater.

Purkinje fibers

The site where the current is initiated for rhythms originating from the ventricles, which have a rate of automaticity of $20-40$ beats per minute.

Premature Ventricular Contractions (PVC)

An ectopic beat originating from the ventricles that occurs early in the cycle, often showing a QRS duration greater than $0.12$ seconds with a T wave in the opposite direction.

Unifocal PVCs

Early beats that display a similar shape, indicating only one irritable focus is present.

Multifocal PVCs

Premature ventricular contractions that exhibit varied shapes and forms.

Interpolated PVC

A PVC that occurs during the normal R-R interval without interrupting the normal cycle.

Bigeminy

A pattern in which every other beat is a PVC.

Trigeminy

A pattern in which every third beat is a PVC.

Quadgeminy

A pattern in which every fourth beat is a PVC.

Coupling

A condition where two PVCs occur back to back.

R on T PVCs

A PVC that occurs on the T wave or the vulnerable period of the ventricle refractory period.

Ventricular Tachycardia (Vtach)

A condition where three or more PVCs occur in a row, with a ventricular rate of $100-200$ beats per minute and usually an absent P wave.

Ventricular Fibrillation (V fib)

Chaotic asynchronous electrical activity within ventricular tissue resulting in no cardiac output and a ventricular rate, if identifiable, greater than $300$ beats per minute.

Asystole

Also known as a straight line or flat line, this condition involves no electrical activity and no measurable waveform.

Electronic Pacemakers

Devices that deliver electrical impulses to the myocardium to cause cell depolarization; they can pace the atria, ventricles, or both.

Electronic Pacemaker Spikes

Thin spikes on an ECG tracing indicating electrical current from a pacemaker, followed by either a P wave or QRS complex.

AV Delay

The interval measured from the atrial spike to the ventricular spike, normally $0.12-0.20$ seconds.