Assessment of Arrhythmias

Assessing For Arrhythmias

Let’s Refresh!

This week we will be looking further at the cardiovascular system and specifically focus on arrhythmias and the heart. Over the past few weeks, we have looked at obtaining a health history related to the patient’s heart, observed the normal heart and circulatory system, and learned ways to assess the extremities and neck vessels. We also learned where to locate the main assessment points of the heart and we learned about nutrition related to the heart. Today we will learn about the electrical conduction throughout the heart and how the heart may be altered if the electrical conduction system is altered.

The Conduction System

Below, is a picture of the conduction system throughout the heart. Impulses within the heart, innervated by nerve tissue, are responsible for depolarization of the heart (causes the heart to contract). In a normal heart, the person’s sinoatrial node (SA node) is responsible for the heart’s electrical impulse. This is the pacemaker of the heart. In many arrhythmias, however, the electrical impulse comes from an area other than the SA node. With normal conduction, the impulse will start with the SA node, located in the atria of the heart. It then travels via internodal pathways to the atrioventricular node (AV node) and then the Bundle of His. From there, the impulse goes to the right and left bundle branches. On the left side, the bundle branch transitions to two fascicles, the anterior and posterior. From here, the heart’s Purkinje Fibers are excited which are located on either side of the ventricle’s walls. All of this happens in approximately 0.12 seconds in the normal heart! Once the impulse has traveled to the Purkinje Fibers a ventricular contraction occurs (Lewis, Heitkemper, Dirksen, O’Brien, & Bucher, 2007).

conduction

So What is an Arrhythmia?

In short, it is very important as the nurse, to understand what arrhythmias are. Although the SA node is the normal pacemaker for the heart, cardiac cells in any part of the heart may take on the role of the pacemaker. Arrhythmias are typically categorized according to the site of the pacemaker and therefore include sinus arrhythmias, atrial arrhythmias, junctional arrhythmias and AV blocks and ventricular arrhythmias and bundle-branch blocks.  Three commonly seen arrhythmias are sinus bradycardia, sinus tachycardia and atrial fibrillation (Huff, 2012).


The Most Common Arrhythmias

(Below, please find a list of the most common arrhythmias. Without going in depth on each arrhythmia, a rhythm strip is provided for each to better visualize what to expect when heart monitoring is utilized.)

Sinus Bradycardia and Sinus Tachycardia

Both sinus bradycardia and sinus tachycardia share the same characteristics as that of normal sinus rhythm (rhythm originates in the SA node, P waves are of normal size, shape and direction and precede every QRS complex, PR interval and QRS complexes are normal) with the exception of the heart’s rate.  The distinctive feature in sinus bradycardia is a slower rate of 40-60 beats per minute. In sinus tachycardia the rate speeds to a range of 100-160 beats per minute (Huff, 2012).  

SB

ST

 

Atrial Fibrillation

In atrial fibrillation (the most common rhythm seen next to sinus rhythm), electrical impulses originate from an ectopic site in the atria instead of from the SA node. Rapid firing from this ectopic site cause the atria to quiver instead of contracting normally resulting in rapid, irregular and chaotic electrical impulses. Typically the AV node blocks most of the impulses from entering the ventricles resulting in a ventricular rate that is slower than its accompanying atrial rate. Unlike the aforementioned sinus arrhythmias, the rhythm is highly irregular. Because atrial impulses are so rapid, often as fast as 400 beats per minute, P waves are often described as fibrillatory wavy deflections that cannot be counted. The slower ventricular rate (which is less than the atrial rate) is represented by normal QRS complexes but no PR interval is discernable (Huff, 2012).

 AFIB

Ventricular Fibrillation (VF)

With this rhythm, the heart’s ventricles serve as the area for electrical conduction. Impulses are disorganized and chaotic, so much that ventricular depolarization and contraction cannot occur. The ventricles instead will quiver, thus creating fibrillatory waves on a ECG strip. VF is the most common cause of cardiac death. Causes of this arrhythmia include myocardial infarction, hypoxia, cardiomyopathy, electrolyte imbalance, and digitalis toxicity. When a person has VF, there is no cardiac output and the nurse will not be able to assess peripheral pulses or blood pressure (Huff, 2012).

 VFIB

Ventricular Tachycardia (VT)

This arrhythmia produces impulses at a rate of 140 to 250 beats per minute. VT is most likely caused by reentry into the ventricles, however, may also be caused by heightened automaticity in the ventricles. This occurs during ventricular repolarization. The electrical impulse originates in the ventricle, therefore the SA Node does not act as the pacemaker for the heart, thus no P wave can be visualized. The rhythm is usually regular, however. This rhythm is often seen in patients with heart disease, and in those with a past medical history of coronary artery disease, myocardial infarction, and congestive heart disease (Huff, 2012).

 VTACH

AV Heart Blocks

There are several types of heart blocks. A heart block forms when there is a delayed conduction and electrical impulse within the heart or failed conduction through the AV node to the ventricles. With this set of heart blocks, the impulse occurs at either the AV node, the bundle of His, or the bundle branches (Huff, 2012).

 

Assessing for the Signs and Symptoms of an Arrhythmia

When assessing the patient for dysrhythmias, the nurse wants to look for several different indicators. Signs of symptoms that the patient may be experiencing if he/she had an arrhythmia includes the following: palpitations, nausea, vomiting, pallor, diaphoresis, weakness, fatigue, numbness and/or tingling of arms, dyspnea, restlessness, cold and clammy skin, dizziness, syncope, confusion, anxiety, decreased level of consciousness, decreased oxygen saturation, either hypotension or hypertension, irregular rate and rhythm of heart, tachycardia, and bradycardia. The patient may also be experiencing pain. Common locations of pain linked with dysrhythmias include the chest, shoulder, back, neck, jaw, and arm (Lewis, et al., 2007).

Electrocardiogram (ECG/EKG)

An electrocardiogram (ECG/EKG) is a non-invasive test that allows for recording of the electrical activity of the heart. Electrodes placed on the skin allow for detection of the heart’s electrical activity in the form of waves and complexes that can then be displayed on a monitor screen and recorded on ECG graph paper for analysis (Huff, 2012). The ECG allows for the detection of cardiac rhythm, pacemaker activity, conduction abnormalities, and presence of acute injury and myocardial infarct (Lewis, et al., 2007). Below, are two diagrams that show where electrodes are placed on the body when performing an ECG.

       Lead placement combo

Cardiac Monitoring

In addition to the performance of a 12 lead ECG, patients can also be monitored on a continual basis during hospitalization with the use of bedside monitoring. Bedside monitoring makes continual observation of the heart’s electrical activity possible and is used to identify abnormalities in rate, rhythm and conduction and to evaluate pacemaker function and responses to various cardiac medications.  Continuous monitoring can be achieved by the use of hardwire monitoring or telemetry monitoring. In hardwire monitoring; leads placed on the patient’s chest are then attached via a lead cable system to a bedside monitor, whereas with telemetry monitoring (also referred to as wireless monitoring), leads are attached to a portable monitor transmitter that sends the electrical signals to a central monitor, thereby allowing the patient more freedom of movement (Huff, 2012). In the hospital, on a telemetry setting, cardiac monitors are used regularly. Below is a diagram as to where the electrodes are placed on the patient’s chest.

Lead placement combo2

Echocardiogram

ECHO

An echocardiogram, also considered non-invasive testing when used alone, utilizes ultrasound waves to assess the structures of heart valves, chest wall movement, and ejection fraction (Corbett, 2008). The echocardiogram is useful in diagnosing valve abnormalities, congenital cardiac defects, and overall cardiac function. Echocardiogram testing is often combined with other modalities for more detailed information or to obtain more specific information. Examples include stress echocardiogram, pharmacologic echocardiogram and transesophageal echocardiogram (Lewis, et al., 2007).

Holter Monitor

Holter

Holter monitors (also referred to as event monitors), are yet another method of assessing a patient’s cardiac status and to help identify arrhythmias.  Patients wear a portable recorder that stores information for later printing and analysis. The holter monitor is typically worn for a period of 24-48 hours during which time the patient records a diary of their activity and symptoms. The information from the diary is then correlated to rhythm changes (Lewis, et al., 2007).  

 

                                                                     

Stress Testing

Stress Test

Exercise stress tests may be used to evaluate the heart’s response to physical stress or increased oxygen demands. In an exercise stress test, the patient exercises on a treadmill or statioanry bicycle while attached to monitoring equipment that measures blood pressure, the person’s ECG, and even oxygen saturation levels. As the patient exercises, he/she is continually assessed by tyrained staff for the developmment of abnormal cardiac symptoms (syncope, vertigo, dyspena, pallor) and ECG changes that may be indicative of myocardial ischemia or arrhythmias (Lewis et al., 2007). 

Questions the Nurse Should Be Asking to Assess for Arrhythmias

  1. Do you have any history of an irregular heartbeat?
  2. Have you ever had any heart abnormalities as a child?
  3. Do you ever experience palpitations (or any of the other signs and symptoms listed above)?
  4. Are you having any chest pain? If so, please describe where the pain is, if it radiates, what it feels like, and if anything appears to make it worse (deep breath, eating, exposure to cold)?
  5. Do you take any medications for your heart? The nurse should be looking for antidysrhythmic medications such as:

·        – Sodium Channel blockers such as Dilantin (phenytoin), or -Rhythmol (propafenone)

·         –Beta Adrenergic Blockers such as Tenormin (atenolol), -Lopressor (metoprolol), or Betapace (sotolol)

·         –Potassium Channel Blockers such as Betapace (sotolol), or -Cordarone (amiodarone)

·         –Calcium Channel Blockers such as Cardizem (diltiazem), or Calan (verapamil)

·         –Others: Lanoxin (digoxin), or Adenocard (adenosine) (Lewis, et al., 2007)

  1. Are you experiencing any shortness of breath, swelling in your legs, dizziness, feelings that you will pass out?
  2. Have you had any history of heart testing (EKGs, echocardiogram, Holter monitoring) If so, what were the findings of the test?
  3. Have you had any surgeries to your heart or around your heart? Any history of a pacemaker? Any cardioversion? Any cardiac ablation? Any cardiac catheterization?
  4. Do you have any family history of having an arrhythmia or any other heart related issues?
  5. Have you had recent cholesterol levels checked? How has your blood pressure been lately?

Other Ways to Assess for Dysrhythmias

Auscultation

Perhaps one of the best ways to assess the conduction system is by directly listening to the heart. Turbulence caused by movement of the valves of the heart creates heart sounds which are heard through the stethoscope. In earlier weeks, we learned about S1 and S2/lub dub sounds. The nurse again wants to use this technique to assess the patient’s current heart rhythm (Lewis, et al., 2007).

Palpation

The nurse should also be using palpation to better assess the patient’s rhythmic status. While simultaneously auscultating the apical area, the nurse should be palpating the radial pulse. The nurse should be feeling for regularity of heart beat. If the apical and radial pulses are not equivalent, one nurse should count the apical pulse while a second nurse counts the radial pulse through palpation. The difference between these two values is known as a PULSE DEFECIT. If the patient is experiencing a pulse deficit, a dysrhythmia is indicated (Lewis, et al., 2007).

WARNING!!

As the nurse, it is important to not rely solely on cardiac monitoring related to cardiac assessment. Computerized monitoring is not fail-proof. When in doubt, check your patient! The heart monitor should not be the only tool the nurse uses to assess the patient’s cardiac status (Lewis, et al.).

Check Out These Videos

1. This video, “Electrocardiogram – What is an ECG – Performing an EKG Video.flv” briefly discusses what an ECG is and why the test is performed. It also discusses a stress test, as well.

2. This video provides an easy to follow visual to better understand how electrical impulses conduct within the heart & the most common dysrhythmias. “The Different Types of Heart Arrhythmia.”

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