Guide For Arrhythmia Recognition Cheryl Sabin, MSN, ANP And other ANP faculty, Indiana University

Objectives Recognize and explain the basic conduction system of the heart Able to accurately measure: PR interval QRS duration QT interval Analyze the rate and rhythm of EKG strips

Objectives Recognize and distinguish what area of the conduction system is pacing the heart Able to state appropriate treatment responses to various identified rhythm strips

The ECG Electrodes on the skins surface records the electrical activity of the heart. Monitoring cables are connected to the skin electrodes and attached to the monitor or ECG machine The horizontal axis corresponds with time. The vertical axis = voltage or amplitude.

ECG Paper ECG paper normally records at 25mm/se Each horizontal 1mm box represents 0.04 sec. (25mm/sec x 0.04 sec = 1mm). Show Basic Dysrhythima

ECG Paper The lines between every 5 boxes are heavier indicating one large box. Each large horizontal box is 0.20 sec 5 large boxes = 1 sec. Thirty large boxes = 6 sec. A small box is 1 mm high, a large box is 5mm high.

Paper

Waveform Movement away from the baseline in either a positive or negative direction Segment A line between waveforms; named by the waveform that precedes or follows it Interval A waveform and a segment Complex Several waveforms

*Waveform* P Wave: represents atrial depolarization and the spread of the electrical impulse throughout the right and left atria. P Wave Characteristics: Smooth & round No more than 2.5 mm in height or 0.11 sec in duration First ½ of the P reflects stimulation of the right atrium. The downward slope of the P represents stimulation of the left atrium

PR PR Segment: horizontal line between the end of the P wave and the beginning of the QRS complex. Normally isoelectric PR Interval: P wave + PR segment = PRI Represents the interval between the onset of atrial depolarization and ventricular depolarization.

PRI Time from impulse from SA to AV node

PR Cont. PR Interval cont. Measured from the point where the P wave leaves the baseline to the beginning of the QRS. Normally measures 0.12 to 0.20 sec. Normally shortens as heart rate increases.

QRS QRS Complex: consists of the Q, R, & S waves and represents the spread of electrical impulse through the ventricles. Ventricular depolarization. Q Wave: is always a negative waveform. It represents depolarization of the interventricular septum Measures less than 0.04 sec in duration and less than 25% of the amplitude of the R wave.

Waveforms R Wave: is the first positive deflection of the QRS S Wave: is a negative deflection following a R wave.

Waveforms The R & S wave represents the simultaneous depolarization of the R & L ventricles. The QRS complex typically represents the electrical activity which occurs within the Left ventricle due to it’s greater muscle mass.

QRS Measuring of QRS The width of the QRS is taken from the point where the first wave of the complex leaves the baseline. The point at which the last wave form returns to the baseline marks the end of the QRS complex. Duration of the QRS varies between 0.06 and 0.10 sec.

ST ST Segments: portion between the QRS complex and the T wave. Is the term used regardless of the final wave of the QRS. Represents the early part of repolarization of the R&L ventricles. Normal ST segment is isoelectric

Waveforms T Wave: Represents ventricle repolarization. The absolute refractory period ends at the peak of the T wave and the relatively refractory period begins.

Waveform T Wave Characteristics: The T wave is typically oriented in the same direction as the preceding QRS complex. The T wave is slightly asymmetric

QT QT Interval: Represents the time from ventricular depolarization to repolarization. QT is measured from the beginning of the QRS complex to the end of the T wave. To determine if the QT is WNL: measure between R-R waves. If the QT interval is less than ½ the R-R interval it is considered normal.

QTc Interval Table HR/min R-R Interval (sec) QTc (sec) & Normal range 40 1.5 0.46(0.41-0.51) 50 1.2 0.42(0.38-0.46) 60 1.0 0.39(0.35-0.43) 70 0.86 0.37(0.33-0.41) 80 0.75 0.35(0.32-0.39) 90 0.76 0.33(0.30-0.36)

QTc Interval Table HR/min R-R Interval (sec) QTc (sec) & Normal range 100 0.60 0.31(0.28-0.34) 120 0.50 0.29(0.26-0.32) 150 0.40 0.25(0.23-0.28) 180 0.33 0.23(0.21-0.25) 200 0.30 0.22(0.20-0.24)

Calculating Rate Assess the Rate: Six-second Method: 30 large boxes = 6 sec. Ventricular Rate: count the number of QRS complexes in the 6 sec. strip and multiply that number by 10. Large Box Method: Count the number of large boxes between 2 consecutive R waves and divide into 300. May also calculate the Atrial rate the same way.

Calculating Rate Sequence Method: Select an R wave that falls on a dark vertical line. Number the next 6 consecutive dark vertical lines as follows: 300, 150, 100, 75, 60, and 50.

Sinus Rhythms Normal Sinus Rhythm or Regular Sinus Rhythm(NSR,RSR) Rate: 60-100. Rhythm: regular. P waves Configuration: All look alike; upright in standard leads I,II, aVF, inverted in aVR P-R interval: Normal 0.10-0.20 seconds and constant QRS duration: Normal 0.04-0.12 seconds.

NSR

Sinus Bradycardia Rate: less than 60 beats per minute. Rhythm: Regular. P waves: Configuration: all look alike(see NSR) one P before each QRS. P-R interval: Normal 0.10-0.20 seconds and constant. QRS duration: Normal 0.04-0.12 seconds.

Sinus Brady What drugs induce SB? When do you treat SB? Why do they have symptoms? Cardiac output = ( HR X SV)

Sinus Tachycardia (Sinus Tach) Rate: 100-150( maybe 180, depends on who’s book you read!) Rhythm: Regular P waves: All look alike( see NSR). One P wave before each QRS PRI: Normally shortens as heart rate increases. QRS duration: Normal 0.04-0.12 sec.

Sinus Tach

Sinus Arrhythmia (happens to all of us!) Rate: 60-100 but it is variable. Rate increases with inspiration and decreases with expiration. Rhythm: Irregular; varies with respiratory cycle

Sinus Arrest Rate: Variable; often slow Rhythm: Interrupted by pauses when the SA node “fails to fire.” Regular until absence of a P wave; duration of the pause is not a multiple of the P-P interval or the underlying rhythm

Sinus Arrest

Sinus Block(SA Exit Block) Impulse originates in pacemaker cells of SA node but is blocked as it exits. Rate: Variable; often slow Rhythm: Regular except for pause periods; overall the rhythm is not interrupted.

SA block

Atrial Arrhythmias Premature Atrial Contractions P waves: Shape of premature P wave often differs. One P wave for each QRS. PAC occurs early; no compensatory pause(usually). P-R interval: Interval for PAC usually different than is sinus cycles. QRS duration: Normal duration; QRS of premature beat usually the same as the sinus conducted QRS Rhythm: Interrupted by premature contraction

NSR PAC

Atrial Tachycardia Paroxysmal Atrial Tach-PAT Rate: 180-250 Rate is the only difference from Sinus Tach. Rhythm: Regular unless associated with AV block-PAT marked by sudden onset and sudden cessation. P waves: Often buried in preceding T wave-tent like appearance.One P for each QRS P-R interval: Not measurable because of rapid rate.

Atrial Flutter Rate: Ventricular rate varies depending upon the degree of AV block( 250-350).It is Regular. Rhythm: Dependent on block; regular if block is constant P Waves: Flutter waves are saw tooth pattern or undulating atrial waves. P-R interval: Not measured. QRS duration: Normal

A. Flutter pathways In atrial flutter, the electrical signal gets trapped in a loop running around the right atrium, causing it to beat at 300 beats per minute while the ventricles beat usually at 150 beats per minute. The abnormal tissue causing this rhythm problem is located near the bottom of the right atrium . This area is easy to reach with the ablation catheter but it may be thick and uneven, making it somewhat difficult to burn all the tissue necessary to eliminate the flutter. The success rate for a first attempt is in the order of 80-90%. The most important risk is the possibility of burning a hole in the heart wall in this region (less than 1%).

A. Flutter

A. Flutter

??? What if the rate is so fast you can’t tell what they are in???? What is SVT? What does this do to CO?

SVT vs. A.Flutter Rhythm strip following Adenosine

Atrial Fibrillation Ventricular rate Atrial rate: 350-500 > 100 = uncontrolled <100 = controlled Atrial rate: 350-500 Rhythm: Usually Irregular ! P waves: Not identifiable P-R interval: Can’t be determined QRS duration: Normal

A. Fib. Electrical Pathways Atrial fibrillation (often called "A Fib") is most commonly seen in people who have other heart disease (such as heart valve problems, heart attacks, long-standing high blood pressure) or thyroid disease but can be seen in otherwise healthy people without any medical problems. The atria become scarred and irritable and are not able to pass the electrical impulse smoothly like a ripple traveling across a calm water pond. Instead, the electrical impulse breaks up into many smaller ripples that travel around the atria in a very fast, irregular and disorganized manner much like a stormy ocean surface. This makes the atria beat at between 300-600 beats/minute. A proportion of these impulses travel down the AV node and cause the ventricles to beat quite fast (120-190 beats/min) and very irregularly. The atria beat so fast that blood does not get pumped normally and blood clots tend to form in the atria. Therefore, blood thinners are often prescribed. Atrial fibrillation is often very difficult to control with drugs.

A. Fib

A. Fib

Class I Benefit >>> Risk Procedure/ Treatment SHOULD be performed/ administered Class IIa Benefit >> Risk Additional studies with focused objectives needed IT IS REASONABLE to perform procedure/administer treatment Class IIb Benefit ≥ Risk Additional studies with broad objectives needed; Additional registry data would be helpful Procedure/Treatment MAY BE CONSIDERED Class III Risk ≥ Benefit No additional studies needed Procedure/Treatment should NOT be performed/administered SINCE IT IS NOT HELPFUL AND MAY BE HARMFUL AHA

AHA

Wandering Pacemaker Rate: usually slow, but may be 60-100 Rhythm: usually regular, but there is no reason it has to be! A wandering atrial pacemaker may be a normal phenomenon seen in the very young or the aged and in athletes. Caused by the inhibitory vagal parasympathetic effect of respiration on the SA node and AV junction. IT may also be caused by the administration of digitalis.IT is not usually significant,and treatment is not indicated. When the heart slows excessively, the signs and symptoms, clinical significance, and management are the same as those in symptomatic sinus bradycardia.

Wandering Pacemaker P waves: May vary depending on the origin of the impulse. One P for each QRS (maybe) P-R interval: Varies as pacemaker wanders between SA node, atrial tissue, and AV node. QRS duration: Normal A wandering atrial pacemaker may be a normal phenomenon seen in the very young or the aged and in athletes. Caused by the inhibitory vagal parasympathetic effect of respiration on the SA node and AV junction. IT may also be caused by the administration of digitalis.IT is not usually significant,and treatment is not indicated. When the heart slows excessively, the signs and symptoms, clinical significance, and management are the same as those in symptomatic sinus bradycardia.

WAP