Clinical Electrocardiography: Review and Study Guide pdf download

Saunders, Philadelphia, , p. Murphy ML, et al. Sensitivity of electrocardiography criteria for left ventricular hypertrophy according to type of cardiac disease. Am J Cardiol ;— Mason JW, et al. American College of Cardiology, Clinical implications of electrical heterogeneity in the heart: the electrophysiology and pharmacology of epicardial, M, and endocardial cells. Cardiac Arrhythmia: Mechanisms, Diagnosis and Management.

Sgarbossa EB, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle branch block. N Engl J Med ;— Yamaji H, et al. Prediction of acute left main coronary artery obstruction by lead electrocardiography: ST segment elevation in lead aVR with less ST segment elevation in lead V1.

J Am Coll Cardiol ;— Wagner GS. Barrabes JA, et al. Prognostic value of lead aVR in patients with a first non-ST segment elevation acute myocardial infarction. Circulation ;— Use of the electrocardiogram in acute myocardial infarction. Constant J. Learning Electrocardiography: A Complete Course, 2nd ed.

It will also be reflected in the calibration mark. EKG tracings begin or end with a calibration marker. The calibration marker looks like an upside-down U-shape with degree angles. If the speed of the tracing is altered, the calibration marker will be altered as well.

However, based on the general health or physical condition of the patient, positioning alterations might be needed. If this occurs, make sure to document alterations.

The preferred position is a supported supine position without pillows. As a last resort, a more elevated position can be warranted. The patient will lie with their arms to their side and shoulders relaxed. Patients in the later stages of pregnancy can need to be positioned on their right side with a pillow supporting their back.

This type of cardiac testing is used more in ongoing inpatient or outpatient monitoring or during emergency transports.

The positioning depends on the individual circumstance. For electrode placement, it is important that the patient assume a comfortable relaxed position, which can be sitting, standing, or lying.

The patient can be ambulatory during testing, which would require additional instructions based on the test being performed. In addition to considering the position when placing the leads, patients undergoing continuous heart monitoring in the outpatient setting should receive information about the device and how to troubleshoot common problems.

To ensure patient understanding of Holter monitor procedures, ask the patient to verbalize the correct response to the following commonly asked questions. Stress testing. The patient will be positioned on a treadmill with electrodes and leads attached to the chest and connected to a cardiac monitor.

The patient should have a chair and railing nearby for support. A stationary bike with accessible handrails can also be used in place of the treadmill. The provider must be present during a stress test. Never leave a patient alone when performing a stress test. The first step is to ensure all supplies and equipment are gathered and ready for testing. These items include the following. Instruct patients to avoid applying any substances to the skin lotions, powders, oils, ointments prior to testing.

The skin should be clean and dry. Use alcohol wipes, soap and water, or commercially prepared electrolyte pads at the attachment sites prior to placement of the electrodes to reduce artifacts. In addition, the surface must have minimal hair in order for the electrodes to adhere to the skin. If the electrodes cannot be properly placed with normal skin prep, the next step is to request permission from the patient to clip or shave the hair at the electrode placement site.

The most commonly used approaches are the , sequence, and 6-second methods. The rhythm must 3. When calculating the heart rate using this method, count the number of small boxes between two R waves. Next, divide 1, by that number to determine the ventricular rate. The same calculation can be used to obtain the atrial 75 60 rate by counting the small boxes between two P waves.

Sequence method The sequence method also known as the method or R-R method is similar to the method segment. A section or part but calculates heart rate using the large boxes instead of the small ones. There are large 5 mm of the electrical activity boxes in every minute of EKG tracing at the standard speed. Calculate the heart rate using this produced by the heart and method by dividing by the number of large boxes between R waves.

Remember the pattern recorded on the EKG tracing. Find an R wave, and start counting toward the right of the tracing in 5 mm segments. With every move, apply the number in the pattern. Do not add the small boxes into the calculation, even if the R wave falls in the middle of the big boxes. This method is not as accurate as the method but provides a means to do a quick calculation that is fairly accurate when the heart rate is regular. Do not use this method with irregular rhythms.

This method is routinely used in estimating the rate, and is especially useful when the rhythm is irregular. At the top of the tracing, there are small hash marks indicating 3-second intervals.

Between each hash mark are 15 boxes. At the standard print speed, the hash marks and boxes will deliver 3-second intervals. Count the number of QRS complexes in two of the sections 6-second period or 30 boxes and multiply by Calculating maximum and target heart rate NOTE Maximum heart rate is calculated using the following formula.

Calculating target heart rate adds one more consideration: the percent of maximum the patient should achieve. First, calculate the maximum heart rate.

The EKG technician is not expected to diagnose conditions but must have an awareness of normal vs. It amplitude. Gain or voltage. Time is measured horizontally, and voltage or amplitude is measured time vertically.

Each small block horizontally on the EKG graph paper represents 0. There are 1 mm five small blocks between each solid line. Therefore, each solid block represents 0. When 0. The P wave represents atrial depolarization and begins when the sinoatrial SA node fires. P waves are normally positively deflected. Variances in the shape of the P wave or repolarization.

The missing P waves could indicate electrical conduction pathway abnormalities. The QRS complex represents ventricular depolarization. Atrial repolarization is not for depolarization. The height of each QRS complex should be evaluated for uniformity. It is measured from the end of the PR interval which is also the beginning of the Q wave , and ends at the J point.

The normal QRS complex ranges from 0. Abnormalities in width of the QRS complex are usually noticeable and indicative of ventricular dysfunction. J point. The J point represents the exact point in time where ventricular depolarization stops, and ventricular repolarization starts.

During ischemia. Decrease in oxygenation of tissues myocardial ischemia, the J point can elevate or depress below baseline. T wave. The T wave represents ventricular repolarization. T waves should follow each QRS complex after a brief pause following the J point. The T waves should appear uniform in configuration. U wave. The U wave is not always visible but represents a repolarization of the bundle of His and Purkinje fibers.

It will be represented by a small upward curve and usually follows the T wave. PR interval. The PR interval represents the time it takes for the SA node to fire, atria to depolarize, and electricity to travel through the AV node—or the time from the beginning of atrial depolarization to the beginning of ventricular depolarization. It starts at the beginning of the P wave and ends at the beginning of the Q wave.

The normal PR interval ranges from 0. The P-P interval represents the amount of time between atrial depolarization cycles between P waves. The P-P interval is R 5mm 0. It is valuable in analyzing rate and rhythm. The R-R interval represents the amount of time between T ventricular depolarization cycles between R waves. In other words, it represents interval interval one complete cycle of ventricular depolarization and repolarization. The QT interval is measured from the beginning of the Q wave to the end of the T wave.

PR segment. The PR segment begins at the end of the P wave and ends at the beginning of the Q wave. It represents the time between the end of atrial contraction and the beginning of ventricular contraction. This slight delay is the time period when the AV node has received the impulse from the SA node and slows the impulse to allow the ventricles to fill prior to contracting.

ST segment. The ST segment represents the early phase of ventricular repolarization. The shape of the ST segment is very important when looking for patterns of ischemia. It starts at the end of S wave and ends at the beginning of the T wave. It represents the time from the end of ventricular depolarization to the beginning of ventricular repolarization.

It sends impulses through the electrical conduction pathway of the heart. It fires impulses at a rate of 40 to 60 beats per minute. The pacing produced in the ventricles are slow, firing impulses at 20 to 40 beats per minute. They are not very effective and only tend to fire when the other two have failed. Arrhythmias are classified based on these three locations.

SA node arrhythmias Arrhythmias originating from the SA node are easily detected. The P wave should be the focal point when analyzing the EKG strip. Normal sinus rhythm is indicated by the following. Sinus bradycardia is not necessarily abnormal.

For some athletes, patients who have medical conditions bradycardia. A such as hypothyroidism, or older adults who live a basically sedentary lifestyle, this rate might be slow heart rate.

Tachycardia is normal during exercise or could be present with medical conditions such as hyperthyroidism. So it is not necessarily abnormal for some individuals or under specific circumstances. Sinus dysrhythmia 3. It is most likely associated with normal breathing patterns. Sinus arrest Sinus arrest is a break in the normal EKG pattern.

In this condition, the SA node failed to fire; it is not significant unless the arrest lasts longer than 6 seconds. A rapid heart rate. It is a condition in which the atria are contracting at a rate much faster than the ventricles are contracting. Atrial fibrillation Atrial fibrillation is even more severe, as there is no organized contraction of the atria. They are in a quivering state, where blood clot formation due 3. Rapid, wavelike contractions. State of quivering with no organized contraction.

Because the fourth, and fifth cardiac cycle impulses are being generated at the AV junction, electrical activity to the atria flows backward, which will result in an inverted P wave configuration. The AV node initiates the impulses when the SA node has been damaged.

Premature junctional complex Premature junctional complex PJC is an early impulse that occurs before the next expected beat. The P wave could occur before, after, or even buried within the QRS complex, which causes an irregularity in the 3. The atria and ventricles will receive the impulse simultaneously, which can result in an absent P wave— but if recognizable, it will be inverted.

The patient can exhibit signs of reduced cardiac output due to the slower heart rate and lack of atrial kick. It is unlikely that the patient will exhibit signs of decreased cardiac output. The excitement of the atria with a rise in internal pressure to forcefully push blood into the ventricles. The faster the rate, the more likely the patient is to experience symptoms of palpitations or fluttering.

Supraventricular tachycardia or narrow complex tachycardia 3. It is included here because the impulse comes from any area above the ventricles. In this situation, the impulse is not following the normal electrical conduction pathway. Due to the rapid nature of the heart rate, P waves are usually not visible. Premature ventricular complexes 3. A P wave is not visible, and the QRS complex is often wider than normal with an unusual shape. Many individuals experience occasional benign PVCs in which they feel palpitations or fluttering in their throat or chest.

The severity related to PVCs depends on their frequency and the reduction in cardiac output. PVCs are classified as occasional if there are one to five in 1 minute, and frequent if there are six or more per minute.

Possible PVCs patterns include the following. There is a continuous state of contraction and relaxation of the ventricles, resulting in a poor cardiac output. There are no noticeable P waves in the tracing. The QRS complexes are wide and unusual, with the T wave deflected in the opposite direction.

There might be few symptoms with this dysrhythmia initially. Without intervention, it will progress quickly as decreased tissue oxygenation occurs.

There are no discernible waves noted throughout the tracing. This dysrhythmia is not compatible with life. If the heart stops, the patient has no rhythm noted and the EKG will demonstrate asystole. Other rhythms that are consistent with a dying heart can be present. Patients will likely be asystole. The absence of any unconscious due to extremely poor cardiac output and tissue oxygenation. Idioventricular rhythm 3.

The QRS complex is wide with an unusual appearance. Heart blocks Heart blocks occur when there is a block somewhere in the electrical conduction pathway, which results in delayed or absent ventricular depolarization. The severity depends on the location and cause of the blockage. But the current that would normally go down the left bundle moves to the left ventricle via the septum, which results in an abnormal right to left stimulation. Because the right side is blocked, the Damage or interference in the left ventricle is able to send impulses through the myocardium to the right ventricle in order to electrical pathway through depolarize the right ventricle.

First-degree atrioventricular block 3. The impulse still travels through the normal pathway but is delayed. As a result, the PR interval will be greater than the normal 0. The patient will not likely exhibit symptoms for this type of block. Second-degree atrioventricular block, type I This is also known as Mobitz I or Wenckebach for the person who 3. In this type of block, there are nonconducted or blocked type I impulses from the AV node to the ventricles.

As a result, there will be missing QRS complexes. The PR interval will get progressively longer until a QRS is dropped, and then the pattern repeats itself. The PR complete heart block interval remains constant, but during the tracing it is noted that a P wave is present with no QRS complex or T wave. In this situation, the AV node has selectively blocked specific impulses. This type of heart block tends to progress quickly to complete heart block.

Third-degree atrioventricular block Third-degree atrioventricular block—also known as complete heart block CHP —occurs when all electrical impulses that originate above the ventricles are blocked. There is no pattern to the cardiac cycle as the atria and ventricles are contracting independently. Which of the following describes coupled 2. A rhythm strip demonstrates a progressively multifocal PVCs? Wide QRS complexes and no P waves before a QRS complex, a variable atrial rate, and occurring on every other beat some irregularity in rhythm.

Which of the following does this describe? Wide QRS complexes of equal shape and configuration occurring together A. Ad veri latine efficiantur quo, ea vix nisl euismod explicari.

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