DYSRHYTHMIAS.docx - Lewis Medical-Surgical Nursing 9th...

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Lewis: Medical-Surgical Nursing, 9 th Edition Chapter 36 Black bold = my notes from Iggy Mark said to memorize the intervals of the heart on a rhythm strip, and what they indicate Nursing Management: Dysrhythmias KEY POINTS RHYTHM IDENTIFICATION AND TREATMENT The ability to recognize normal and abnormal cardiac rhythms, called dysrhythmias , is an essential nursing skill. Four properties of cardiac cells (automaticity, excitability, conductivity, and contractility) enable the conduction system to start an electrical impulse, send it through the cardiac tissue, and stimulate the myocardial tissue to contract. The autonomic nervous system plays an important role in the rate of impulse formation, the speed of conduction, and the strength of cardiac contraction. Electrocardiogram Monitoring The electrocardiogram (ECG) is a graphic tracing of the electrical impulses produced in the heart. ECG waveforms are produced by the movement of charged ions across the semipermeable membranes of myocardial cells. There are 12 recording leads in the standard ECG. Changes in a 12-lead ECG may occur with ischemia, infarction, electrolyte imbalance, conduction disturbances, dysrhythmias, or drug toxicity. Continuous ECG monitoring is done using one or more leads and based on the patient’s clinical status. Telemetry monitoring involves the observation of a patient’s heart rate (HR) and rhythm to help rapidly diagnose dysrhythmias, ischemia, or infarction. Normal sinus rhythm starts in the sinoatrial (SA) node and follows the normal conduction pattern of the cardiac cycle. o The P wave represents the depolarization of the atria (passage of an electrical impulse through the atria), causing atrial contraction. o The PR interval represents the time period for the impulse to spread through the atria, atrioventricular (AV) node, bundle of His, and Purkinje fibers. 0.12-0.20 second (5 small boxes) o The QRS complex represents depolarization of the ventricles (ventricular contraction). 0.04-0.10 second (up to three small boxes) o The QRS interval represents the time it takes for depolarization. o The ST segment represents the time between ventricular depolarization and repolarization. This segment should be flat or isoelectric and represents the absence of
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any electrical activity between these two events. o The T wave represents repolarization of the ventricles. o The QT interval represents the total time for depolarization and repolarization of the ventricles. Prolonged qt interval may lead to a unique ventricular tachycardia, TORSADES DE POINTES We don’t want ST elevation or depression (indicates Myocardial Injury, ischemia, or infarction.) U wave may result from slow repolarization of ventricular purkinje fibers Dysrhythmias result from disorders of impulse formation, conduction of impulses, or both.
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  • Spring '17
  • Acevedo
  • Cardiology, Cardiac electrophysiology

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