The article electrocardiogram inter...

The article electrocardiogram interpretation for perioperative nurses" is the basis for this AORN Journal independent consideration The behavioral objectives and examination for this program were prepared at Rebecca Holm, RN, MSN, CNOR, clinical editor, with consultation from Susan Bakewell, RN M education program professional, Center for Perioperative Education.

Participants receive feedback onward incorrect answers. Each applicant who favorably completes this study will receive a certificate of completion. The deadline for submitting this subject of attention is Oct 31, 2006.

clean the examination answer sheet and learner evaluation raise on pages 593-594 and mail with appropriate unconditional tenure to

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BEHAVIORAL OBJECTIVES

After reading and studying the article forward basic electrocardiogram interpretation, perioperative fosters will be able to

1 identify the constitutings of the conduction system of the heart,

2 describe lead placement to perform electrocardiography,

3 explain for what reason the coronary blood supply can affect arrhythmias, and

4 use assessment and rate calculations to interpret harmonious flow strips.

Editor's note: This article is an updated reprint of the electrocardiogram household Study published in the AORN Journal in January 1999

Historically, monitoring and interpreting electrocardiograms (EKGs) intraoperatively have been the responsibility of anesthesia care providers. Changes in health care, however, not rarely have required that perioperative encourages assume this responsibility. Today, perioperative give suck tos are expected to manage an increasing number of patients undergoing IV conscious sedation who require EKG monitoring. Perioperative nourishs also may be expected to be cros trained to the postanesthesia care unit (PACU) and preoperative holding areas. Positive patient consequences are related to their ability to monitor and interpret patients' EKGs

THE CONDUCTION SYSTEM

An EKG is a road map of the electrical activity of cardiac lonely dwellings during the contraction and relaxation of the heart. The sinoatrial (SA) node, atrioventricular (AV) node, and Purkinnje fibers are the normal pacing sites of the heart (Figure 1) In a healthy body an EKG should demonstrate an organized, sequential electrical impulse from its beginning at the SA node to its conclusion at the Purkinje fibers. Cardiac electrical activity immediately take precedence ofs the contraction of cardiac muscle.

[FIGURE 1 OMITTED]

Normal electrical conduction of the heart begins in the SA node, located in the right atrium. The SA node is the natural pacemaker of the heart and has an intrinsic rate of 60 to 100 beats through minute (BPM). Without any other stimulation, the SA node has the ability to initiate an impulse. An impulse initiated by way of the SA node travels between the sides of the atria via the intranodal pathways. This outcomes in depolarization (ie, contraction) of the atria.

The impulse then travels from the atria to the AV node, where it is delayed for 008 to 012 others This delay allows both atria to depolarize before the impulse continues by means of the remaining conduction system pathway. The AV node make steady [i]or[/i] firms excessive atrial impulses from reaching the ventricles, thus preventing cardiac output from dropping to dangerous of the same heights as a result of a fast ventricular rate. The AV node also has the ability to act as the pacemaker for the heart should the SA node fail or the impulses from the SA node become blocked

The cardiac impulse then travels from the AV node to the pack of His, which divides into right and left put into bundles branches that travel to the ventricles. The cardiac impulse terminates with ventricular depolarization, which takes place in the Purkinje fibers located in the muscles of the ventricles. Cardiac dysrhythmias are caused according to disturbances in automaticity (ie, the ability of a confined apartment to generate electrical impulses spontaneously) or conductivity (ie, the ability of the solitary abode; squalid to conduct electrical impulses) or an alteration in both

ELECTROCARDIOGRAPHY

The EKG a tracing of the electrical activity in the heart, is recorded onward heat-sensitive graph paper (Figure 2) Time is measured horizontally, and voltage is measured vertically. upon the EKG graph paper, undivided small square is equal to 004 others in time. One large square contains five of the small squares and, therefore, is equal to 020 inferiors (ie, 5 x 0.04 seconds) A undivided cardiac cycle (ie, one polarization and depolarization of the heart) is exhibited on the EKG by the verbal expressions P, Q, R, S, and T Interval measurements (ie, PR QR QT) forward the EKG assess the longitudinal dimensions of time it takes an impulse to travel between the sides of the heart (Figure 3).

[FIGURE 2-3 OMITTED]

LEAD PLACEMENT. Electrocardiography records the be molten of electrical currents of the heart as they influence away or toward a specific electrode Standard lead placement uses leads I, II, and III, forming Einthoven's Triangle. This equilateral triangle is named for Willem Einthoven, the man responsi ble for developing the first locate of leads used to record electrical activity of the heart. Leads I, II, and III record the result of electrical current by using the limb leads as positive or negative extremitys Lead I is used to record electrical activity at the left lateral wall of the heart. Lead II is the chiefly commonly used lead and is used to record the sweep along of electrical activity in normal atrial and ventricular depolarization. Lead III provides information about the inferior wall of the heart. circulating flowing toward the positive electrode records an upright deflection onward the EKG tracing, and passing from hand to hand flowing away from the positive electrode records a downward, or negative, deflection.