ACLS review: Bradycardia part 2

Third Degree Heart Block

ECG Characteristics

Rate: The atrial rate is typically normal. The ventricular rate will be slower. If a junctional focus is controlling the ventricles, the rate will be 40 - 60. If the focus is ventricular, the rate will be 20 - 40.

Rhythm: Since the atrial and ventricular foci are firing regularly, the P - P and the R - R intervals will be regular.

P Wave: Upright and uniform. There are more P waves than QRS complexes

PRI: There is no PRI, because the block at the AV node is complete. There is no association between the P waves and the QRS complexes.

QRS: If the focus is junctional, less than 0.12 seconds. If the focus is ventricular, the QRS will be > 0.12.

Types of Bradycardia

·         Absolute Bradycardia: Defines bradycardia by heart rate (below 60)

·         Relative Bradycardia: Defines bradycardia by symptoms ( i.e. hypotension with HR of 65)

Symptomatic Bradycardia

·         Symptomatic implies that an arrhythmia is causing symptoms, such as palpitations, lightheadedness, or dyspnea, but the patient is stable and not in imminent danger.

·         In such cases more time is available to decide on the most appropriate intervention

Unstable Bradycardia

·         Refers to a condition in which vital organ function is acutely impaired or cardiac arrest is ongoing or imminent.

·         When an arrhythmia causes a patient to be unstable, immediate intervention is indicated

Serious signs and symptoms

·         Chest pain

·         Syncope

·         Shortness of breath

·         Cold and clammy skin

·         Decreased level of consciousness

·         Hypotension

·         Pulmonary congestion

·         Congestive Heart Failure

·         Acute Myocardial Infarction


Reviewed 2/28/16