DYSRHYTHMIA INTERPRETATION

Approach to Dysrhythmia Interpretation Method to interpret dysrhythmias Identify the waves (P-QRS-T). Measure the PRI. Measure the QRS duration. Determine rhythm regularity.

Rhythm Regularity Measure distance between R waves Regular: distance between R waves is the same From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythm Regularity Measure distance between R waves (cont’d) Irregularly irregular: no two R waves equal Regularly irregular: R waves are irregular but follow a pattern From Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Determining Heart Rate 6-second method Count the number of QRS complexes in a 6-second strip and multiply by 10.

Determining Heart Rate Sequence method Find R wave; count off above sequence until next R wave. If interval spans fewer than three boxes, rate is greater than 100. If more than five boxes, rate is less than 60.

Cardiac Dysrhythmias is a group of conditions in which the heartbeat is irregular, too fast, or too slow. While most arrhythmias are not serious some predispose a person to complications such as stroke or heart failure. Others may result in cardiac arrest.

Symptoms of Dysrhythmias Many arrhythmias have no symptoms. When symptoms are present these may include:- palpitations feeling a pause between heartbeats. lightheadedness. passing out. shortness of breath. chest pain.

Cardiac Dysrhythmias Usually we classify according to site from which they arise.

Rhythms Originating in SA Node Normal sinus rhythm Intrinsic rate of 60 to 100 beats/min Upright P wave preceding each QRS complex Adapted from Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythms Originating in SA Node Sinus bradycardia Rate of less than 60 beats/min Upright P wave preceding every QRS complex Adapted from Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythms Originating in SA Node Sinus bradycardia (cont’d) Serious causes include: SA node disease: sarcoidosis, amyloidosis, hemochromatosis, Chagas' disease, and cardiomyopathies. AMI, which may stimulate vagal tone Increased intracranial pressure Use of beta blockers, calcium channel blockers, morphine, quinidine, or digitalis Treatment focuses on cause.

Rhythms Originating in SA Node Sinus tachycardia Rate is more than 100 beats/min. Upright P waves precede QRS complexes. Adapted from Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythms Originating in SA Node Sinus tachycardia (cont’d) Hypoxia, metabolic alkalosis, hypokalemia, and hypocalcemia can lead to electrical instability. Circus reentry may occur. Adapted from Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythms Originating in SA Node Sinus dysrhythmia Slight variation in sinus rhythm cycling. Upright P waves precede QRS complexes.

Rhythms Originating in SA Node Sinus dysrhythmia (cont’d) More prominent with respiratory cycle fluctuation. Increased filling pressures during inspiration stimulate Bainridge reflex (also called the atrial reflex, is an increase in heart rate due to an increase in central venous pressure ) . Increase in BP stimulates baroreceptor reflex

Rhythms Originating in SA Node Sinus arrest SA node fails to initiate an impulse. Upright P waves precede QRS complexes. Adapted from Arrhythmia Recognition: The Art of Interpretation, courtesy of Tomas B. Garcia, MD.

Rhythms Originating in SA Node Sinus arrest (cont’d) Common causes: Ischemia of the SA node. Increased vagal tone. Carotid sinus massage. Use of certain drugs. Treatment may include a pacemaker.

Rhythms Originating in SA Node Sick sinus syndrome (SSS) Variety of rhythms, poorly functioning SA It shows on an ECG as: Sinus bradycardia Sinus arrest SA block Alternating patterns of bradycardia and tachycardia

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