Care of Patients With Dysrhythmias (Iggy Ch. 34)

The nurse administers amiodarone (Cordarone) to a patient with ventricular tachycardia. Which monitoring by the nurse is necessary with this drug? *Select all that apply.* Respiratory rate QT interval Heart rate Heart rhythm Urine output

2,3,4 - Amiodarone causes prolongation of the QT interval, which can precipitate dysrhythmia. Antidysrhythmic medications cause changes in cardiac rhythm and rate; therefore, monitoring of heart rate and rhythm is needed.Although it is always important to monitor respiratory rate and urine output, these assessments are not specific to amiodarone.

Electrocardiographic Rhythm Analysis: 3. Analyze the P waves.

3. Analyze the P waves. - *Check that the P-wave shape is CONSISTENT throughout the strip, indicating that atrial depolarization is occurring from impulses originating from one focus, normally the SA node.* - Determine whether there is one P wave occurring before each QRS complex, establishing that a relationship exists between the P wave and the QRS complex. This relationship indicates that an impulse from one focus is responsible for both atrial and ventricular depolarization. The nurse may observe more than one P-wave shape, more P waves than QRS complexes, absent P waves, or P waves coming after the QRS, each indicating that a dysrhythmia exists. *Ask these five questions when analyzing P waves:* • Are P waves present? • Are the P waves occurring regularly? • Is there one P wave for each QRS complex? • Are the P waves smooth, rounded, and upright in appearance; or are they inverted? • Do all P waves look similar?

Electrocardiographic Rhythm Analysis: 5. Measure the QRS duration (How long should it be?)

5. *Measure the QRS duration:* - *Place one caliper point at the beginning of the QRS complex and the other at the J point, where the QRS complex ends and the ST segment begins.* The QRS duration normally measures between *0.04 and 0.10 second.* The measurement should be constant throughout the entire strip. *Ask these questions to evaluate QRS intervals:* • Are QRS intervals less than or greater than 0.12 second? • Are the QRS complexes similar in appearance across the ECG paper?

Electrocardiographic Rhythm Analysis: 6. Examine the ST segment.

6. Examine the ST segment. - The normal ST segment begins at the isoelectric line. *ST elevation or depression is significant if displacement is 1 mm (one small box) or more above or below the line and is seen in two or more leads.* - ST elevation may indicate problems such as *myocardial infarction, pericarditis, and hyperkalemia.* *(STEMI)* - ST depression is associated with hypokalemia, myocardial infarction, or ventricular hypertrophy.

Electrocardiographic Rhythm Analysis: 7. Assess the T wave.

7. Assess the T wave. - Note the shape and height of the T wave for peaking or inversion. *Abnormal T waves may indicate problems such as myocardial infarction and ventricular hypertrophy.*

Which waveform indicates proper function of the sinoatrial (SA) node? The QRS complex is present. The PR interval is 0.24 second. A P wave precedes every QRS complex. The ST segment is elevated.

A P wave precedes every QRS complex. - *A P wave is generated by the SA node and represents atrial depolarization and needs to be followed by a QRS complex.* When the electrical impulse is consistently generated from the SA node, the P waves have a consistent shape in a given lead. - *The QRS complex represents ventricular depolarization.* - *The PR interval represents time required for atrial depolarization and for the impulse delay in the atrioventricular node and travel time to the Purkinje fibers.* Normal PR level is *up to 0.20 seconds.* - ELEVATION of the ST segment indicates myocardial injury.

Those at risk for Ventricular Fibrillation

A: Coarse ventricular fibrillation. B: Ventricular *asystole* with one idioventricular complex. - *VF may be the first manifestation of coronary artery disease (CAD).* Patients with myocardial infarction (MI) are at great risk for VF. - It may also occur in those with *hypokalemia, hypomagnesemia, hemorrhage, drug therapy, rapid supraventricular tachycardia (SVT), or shock.* Surgery or trauma may also cause VF.

During routine suctioning of a client with a tracheostomy, the client becomes diaphoretic and nauseous, and the heart rate decreases to 39 beats/min. What is the nurse's best action at this time? A. Continue to clear the airway. B. Stop suctioning the patient. C. Administer atropine. D. Call the health care provider immediately.

ANS: B - *Removing the noxious stimuli causing the vagal response would be the first action.* - If this does not resolve the bradycardia, second action would be to administer atropine (anti-cholinergic) and call provider. - Continuing to suction is not appropriate as this is the cause of the vagal episode.

The primary health care provider prescribes warfarin (Coumadin) for a client with atrial fibrillation. Which statement made by the client indicates that additional education is needed? A. "I need to go to the clinic once a week to have my blood level checked." B. "If my stools turn black, I will be sure to call my primary health care provider" C. "I'm glad I don't need to change my diet. Salads are my favorite food." D. "I need to stop taking my herbal supplement."

ANS: C - *Patients on Coumadin therapy need to avoid foods high in Vitamin K including green leafy vegetables* This is because Vitamin K helps with clotting, therefore antagonizing the effects of Coumadin. - INR needs to be measured frequently - Black stools are a sign of GI bleeding and should be reported - Herbal medications such as Ginkgo biloba interfere with functioning of coumadin.

A client in the telemetry unit is on a cardiac monitor. The monitor technician notices that there are no ECG complexes, and the alarm sounds. What is the first action by the nurse? A. Suspend the alarm. B. Call the emergency response team. C. Press the record button to get an ECG strip. D. Assess the client and check lead placement.

ANS: D - ALWAYS check the patient first. Cardiac monitors are a tool for assessment but they do not replace hands on nursing assessment.

A patient with atrial fibrillation (AF) with rapid ventricular response has received medication to slow the ventricular rate. The pulse is now 88 beats/min. For which additional therapy does the nurse plan? Synchronized cardioversion Electrophysiology studies (EPS) Anticoagulation Radiofrequency ablation therapy

Anticoagulation - The patient's rhythm has stabilized but because of the risk for thromboembolism related to AF, anticoagulation is necessary. - Cardioversion is not needed at this time. EPS are indicated for recurring, symptomatic dysrhythmia. Ablation therapy is ordered for recurring and symptomatic atrial fibrillation.

The nurse is caring for a patient who has developed a bradycardia. Which possible causes does the nurse investigate? *Select all that apply.* Bearing down for a bowel movement Possible inferior wall myocardial infarction (MI) Patient stating that he just had a cup of coffee Patient becoming emotional when visitors arrived Diltiazem (Cardizem) administered 1 hour ago

Bearing down for a bowel movement Possible inferior wall myocardial infarction Diltiazem (Cardizem) administered 1 hour ago - *Valsalva maneuvers such as bearing down for a bowel movement or gagging may cause excessive vagal (parasympathetic) stimulation to the heart leading to decreased rate of sinus node discharge.* - *Bradycardia may result from carotid sinus massage, vomiting, suctioning, ocular pressure, or pain.* - Inferior wall MI is a cause of bradycardia and heart block. - Calcium channel blockers such as diltiazem may cause bradycardia. - *Caffeine intake results in an increased heart rate. Stress, such as an emotional encounter, can result in tachycardia.*

The nurse is caring for a patient with unstable angina whose cardiac monitor shows ventricular tachycardia. Which action is appropriate to implement first? Defibrillate the patient at 200 joules. Check the patient for a pulse. Cardiovert the patient at 50 joules. Give the patient IV lidocaine.

Check the patient for a pulse. - *The nurse needs to first assess the patient to determine stability before proceeding with further interventions.* If the patient has a pulse and is relatively stable, elective cardioversion or antidysrhythmic medications may be prescribed. - T*he drug of choice for stable ventricular tachycardia with a pulse is amiodarone.* - If the patient is pulseless or nonresponsive, the patient is unstable and defibrillation is used and not cardioversion. - *Also, if the patient is pulseless, lidocaine may be given after defibrillation.*

The nurse is caring for a patient on a telemetry unit who has a regular heart rhythm and rate of 60 beats/min; a P wave precedes each QRS complex, and the PR interval is 0.20 second. Additional vital signs are as follows: blood pressure 118/68 mm Hg, respiratory rate 16 breaths/min, and temperature 98.8°F (37°C). All of these medications are available on the medication record. What action does the nurse take? Administer atropine. Administer digoxin. Administer clonidine. Continue to monitor.

Continue to monitor. - The nurse needs to take no action other than to continue monitoring because *the patient is displaying a normal sinus rhythm and normal vital signs.* - *Atropine is used in emergency treatment of symptomatic bradycardia.* This patient has a normal sinus rhythm. - *Digoxin is used in the treatment of atrial fibrillation (A-FIB), which is, by definition, an irregular rhythm.* - *Clonidine (Alpha-2 agonist)* is used in the treatment of hypertension; a side effect is bradycardia.

The nurse is caring for a patient with advanced heart failure who develops asystole. The nurse corrects the graduate nurse when the graduate offers to perform which intervention? Defibrillation Cardiopulmonary resuscitation (CPR) Administration of epinephrine Administration of oxygen

Defibrillation - Defibrillation interrupts the heart rhythm and allows normal pacemaker cells to take over. *In asystole, there is no rhythm to interrupt. Therefore, this intervention is not used.* - If drug therapy fails to restore effective rhythm, CPR is initiated. *Epinephrine is used to increase heart rate in asystole.* - *Hypoxia may be a cause of cardiac arrest, so the administration of oxygen would be appropriate.*

Which risk factors are known to contribute to atrial fibrillation? *Select all that apply.* Use of beta-adrenergic blockers Excessive alcohol use Advancing age High blood pressure Palpitations

Excessive alcohol use Advancing age High blood pressure - *Risk factors contributing to atrial fibrillation include excessive alcohol use, advancing age, and hypertension.* Other risk factors involve previous ischemic stroke, transient ischemic attack or other thromboembolic event, coronary heart disease, diabetes mellitus, heart failure, mitral valve disease, obesity, and chronic kidney disease. - The incidence of atrial fibrillation also occurs more often in those of European ancestry and African Americans. - *Beta-adrenergic blocking agents, which reduce heart rate, are used to treat atrial fibrillation as well as anti-coagulants.* - Palpitations are a *symptom* of atrial fibrillation, rather than a risk or a cause.

Unifocal and Multifocal PVC

FIG. 34-12 Premature ventricular contractions. A: Normal sinus rhythm with *unifocal* premature ventricular complexes (PVCs). B: Normal sinus rhythm with *multifocal PVCs (one negative and the other positive).* - If there is no underlying heart disease, PVCs are not usually treated other than by eliminating or managing any contributing cause (e.g., caffeine, stress). Potassium or magnesium is given for replacement therapy if hypokalemia or hypomagnesemia is the cause. If the number of PVCs in a 24-hour period is excessive, the patient may be placed on beta-adrenergic blocking agents (beta blockers)

How does the nurse recognize that atropine has produced a positive outcome for the patient with bradycardia? The patient states he is dizzy and weak. The nurse notes dyspnea. The patient has a heart rate of 42 beats/min. The monitor shows an increase in heart rate.

The monitor shows an increase in heart rate. - An expected outcome after the administration of atropine is an increased heart rate. *By definition, the bradydysrhythmia has resolved when the heart rate is greater than 60 beats/min.* - Dizziness and weakness indicate symptoms of decreased cerebral perfusion and intolerance to the bradydysrhythmia. - Dyspnea indicates intolerance to the bradydysrhythmia. - A heart rate of 42 beats/min after atropine has been given indicates that bradycardia is unresolved.

The professional nurse is supervising a nursing student performing a 12-lead electrocardiogram (ECG). Under which circumstance does the nurse correct the student? The patient is semi-recumbent in bed. Chest leads are placed as for the previous ECG. The patient is instructed to breathe deeply through the mouth. The patient is instructed to lie still.

The patient is instructed to breathe deeply through the mouth. - *While obtaining a 12-lead ECG, remind the patient to be as still as possible in a semi-reclined position, breathing normally.* Any repetitive movement will cause artifact and could lead to inaccurate interpretation of the ECG. *Normal breathing is required or artifacts will be observed, perhaps leading to inaccurate interpretation of the ECG.* - Placing the patient in a semi-reclined position is correct and does not require the nurse to intervene. ECGs are valid when electrode placement is identical at each test. The patient must lie still to avoid artifacts and inaccurate interpretation of the ECG.

Trigeminy

Trigeminy is a repeated three-beat pattern, usually occurring as two sequential normal complexes followed by a premature complex and a PAUSE, with the same pattern repeating itself in triplets. (2 good, 1 bad... repeat)

Quadrigeminy

Quadrigeminy is a repeated four-beat pattern, usually occurring as three sequential normal complexes followed by a premature complex and a pause, with the same pattern repeating itself in a four-beat pattern. (3 good, 1 bad... repeat)

ST segment ELEVATION is consistent with______

ST segment ELEVATION is consistent with *Myocardial Infarction (MI)*.

A patient's rhythm strip shows a heart rate of 116 beats/min, one P wave occurring before each QRS complex, a PR interval measuring 0.16 second, and a QRS complex measuring 0.08 second. How does the nurse interpret this rhythm strip? Normal sinus rhythm Sinus bradycardia Sinus tachycardia Sinus rhythm with premature ventricular contractions

Sinus tachycardia - These are the characteristics of sinus tachycardia. - *A normal sinus rhythm would have a heart rate of 60 to 100 beats/min.* - A heart rate of less than 60 beats/min would indicate sinus bradycardia. - *Early QRS intervals would indicate sinus rhythm with premature ventricular contractions.*

Excitability / Depolarization

- Excitability is the ability of nonpacemaker heart cells to respond to an electrical impulse that begins in pacemaker cells. - *Depolarization* occurs when the *normally negatively* charged cells within the heart muscle develop a *positive charge.*

What teaching does the nurse include for a patient with atrial fibrillation who has a new prescription for warfarin? "It is important to consume a diet high in green leafy vegetables." "You would take aspirin or ibuprofen for headache." "Report nosebleeds to your provider immediately." "Avoid caffeinated beverages."

"Report nosebleeds to your provider immediately." - *A nosebleed could be indicative of excessive dosing of warfarin.* Warfarin is an anticoagulant and causes decreased ability for blood to clot. - Green leafy vegetables are high in vitamin K, which may antagonize the effects of warfarin; these vegetables would be eaten in moderate amounts. - Aspirin and nonsteroidal anti-inflammatory agents may prolong the prothrombin time and the international normalized ratio, causing predisposition to bleeding. *These agents would be avoided.* - It is not necessary to avoid caffeine because this does not affect clotting; however, green tea may interfere with the effects of warfarin.

In teaching patients at risk for bradydysrhythmias, what information does the nurse include? "Avoid potassium-containing foods." "Stop smoking and avoid caffeine." "Take nitroglycerin for a slow heartbeat." "Use a stool softener."

"Use a stool softener." - The nurse will advise the client to use a stool softener. *Patients at risk for bradydysrhythmias would avoid bearing down or straining during a bowel movement. The Valsalva maneuver associated with bearing down can cause bradycardia.* - Patients with renal failure and hyperkalemia are instructed to avoid potassium-containing foods; if risk for hypokalemia exists, such as with diuretic therapy, the patient is instructed to eat foods high in potassium. - Smoking and caffeine increase heart rate; although all people would stop smoking, patients at risk for tachycardia, premature beats, and ectopic rhythms are instructed to stop smoking and avoid caffeine. - *Nitroglycerin is used to reduce oxygen demand in cardiac ischemia, not for bradycardia.*

Electrocardiographic Rhythm Analysis: 1. Determine the heart rate.

*1. Determine the heart rate:* - *The most common method is to count the number of QRS complexes in 6 seconds and multiply that number by 10 to calculate the rate for a full minute. This is called the 6-second strip method and is a quick method to determine the mean or average heart rate.* - Use caution and confirm that the rate is correct by assessing the patient's heart rate directly. Many factors can incorrectly alter the rate displayed by the monitor.

Electrocardiographic Rhythm Analysis: 2. Determine the heart rhythm. (PP intervals, RR intervals

*2. Determine the heart rhythm:* - *Assess for atrial and/or ventricular regularity.* - Check the regularity of the *atrial rhythm by assessing the PP intervals*, placing one caliper point on a P wave and the other point on the precise spot on the next P wave. Then move the caliper from P wave to P wave along the entire strip ("walking out" the P waves) to determine the regularity of the rhythm. - Check the regularity of the *ventricular rhythm by assessing the RR intervals*, placing one caliper point on a portion of the QRS complex (usually the most prominent portion of the deflection) and the other point on the precise spot of the next QRS complex. Move the caliper from QRS complex to QRS complex along the entire strip (walking out the QRS complexes) to determine the regularity of the rhythm.

Electrocardiographic Rhythm Analysis: 4. Measure the PR interval (How long should it be?)

*4. Measure the PR interval:* - Place one caliper point at the *beginning of the P wave* and the other point at the *end of the PR segment.* The PR interval normally measures between *0.12 and 0.20 second.* - The measurement should be constant throughout the strip. The PR interval cannot be determined if there are no P waves or if P waves occur after the QRS complex. *Ask these three questions about the PR interval:* • Are PR intervals greater than 0.20 second? bad *(1st degree AV Block)* • Are PR intervals less than 0.12 second? bad • Are PR intervals constant across the ECG strip? yes, good

Electrocardiographic Rhythm Analysis: 8. Measure the QT interval.

*8. Measure the QT interval:* - A normal QT interval should be equal to or less than one-half the distance of the RR interval. Using steps 1 through 8, you can interpret the cardiac rhythm and differentiate normal and abnormal cardiac rhythms (dysrhythmias).

Artifact reading on ECG

- *Artifact is interference seen on the monitor or rhythm strip, which may look like a wandering or fuzzy baseline.* - It can be caused by patient movement, loose or defective electrodes, improper grounding, or faulty ECG equipment such as broken wires or cables. - *Some artifact can mimic lethal dysrhythmias such as ventricular tachycardia (with toothbrushing) or ventricular fibrillation (with tapping on the electrode).* - Assess the patient to differentiate artifact from actual lethal rhythms! Do not rely only on the ECG monitor.

Care of Patient with Dysrhythmias

- *Assess the patient's apical and radial pulses for a full minute for any irregularity,* which may occur with *premature beats OR atrial fibrillation.* (This may require 2 people and then compare) - If the apical pulse differs from the radial pulse rate, a *pulse deficit* exists and indicates that the heart is not pumping adequately to achieve optimal PERFUSION to the body. - Dysrhythmias are often managed with antidysrhythmic drug therapy

Atrial Fibrillation (what it is, risk factors, what it can cause?)

- *Atrial fibrillation (AF) is the most common dysrhythmia seen in clinical practice.* AF can be encountered and treated in the ambulatory and acute care settings. - It can impair quality of life and cause considerable morbidity and mortality, largely related to *CLOTTING concerns such as embolic stroke, deep venous thrombosis (DVT) or pulmonary embolism (PE).*

Conductivity

- *Conductivity is the ability to send an electrical stimulus from cell membrane to cell membrane.* - As a result, excitable cells *depolarize* in rapid succession from cell to cell until all cells have depolarized. - The wave of depolarization causes the deflections in the ECG waveforms that are recognized as the *P wave and the QRS complex.* - Disturbances in conduction result when conduction is too rapid or too slow, when the pathway is totally blocked, or when the electrical impulse travels an abnormal pathway.

Contractility

- *Contractility is the ability of atrial and ventricular muscle cells to shorten their fiber length in response to electrical stimulation, causing sufficient pressure to push blood forward through the heart.* - In other words, contractility is the mechanical activity of the heart.

Continuous Electrocardiographic Monitoring

- *For continuous ECG monitoring, the electrodes are NOT placed on the limbs because movement of the extremities causes "noise," or motion artifact, on the ECG signal.* Place the electrodes on the trunk, a more stable area, to minimize such artifacts and to obtain a clearer signal.

Ventricular tachycardia cntd.

- *In some patients, VT causes cardiac arrest.* Assess the patient's circulation and airway, breathing, level of consciousness, and oxygenation level. - For the *stable* patient with *sustained* VT, *administer oxygen and confirm the rhythm via a 12-lead ECG.* - *Amiodarone* (Cordarone), lidocaine, or magnesium sulfate may be given.

Premature complexes

- *Premature complexes are EARLY rhythm complexes.* They occur when a cardiac cell or cell group, *other than the sinoatrial (SA) node*, becomes irritable and fires an impulse before the next sinus impulse is produced. - The abnormal focus is called an *ectopic focus* and may be generated by atrial, junctional, or ventricular tissue. - *After the premature complex, there is a pause before the next normal complex, creating an irregularity in the rhythm.* The patient with premature complexes may be unaware of them or may feel palpitations or a "skipping" of the heartbeat. *If premature complexes, especially those that are ventricular, become more frequent, the patient may experience symptoms of decreased cardiac output.* Premature complexes may occur repetitively in a rhythmic fashion: - Bigeminy - Trigeminy - Quadrigeminy

Normal sinus rhythm (NSR) *(rate, rhythm, P waves)* *(PR interval and QRS duration length)*

- *Rate:* Atrial and ventricular rates of 60 to 100 beats/min - *Rhythm:* Atrial and ventricular rhythms regular - *P waves:* Present, consistent configuration, one P wave before each QRS complex - *PR interval:* 0.12 to 0.20 second and constant - *QRS duration:* 0.04 to 0.10 second and constant FIG. 34-7: Normal sinus rhythm. Both atrial and ventricular rhythms are essentially regular (a slight variation in rhythm is normal). *Atrial and ventricular rates are both 87 beats/min.* There is one P wave before each QRS complex, and all the P waves are of a consistent morphology, or shape. The *PR interval measures 0.18 second and is constant;* the QRS complex measures 0.06 second and is constant.

Supraventricular tachycardia (SVT)

- *Supraventricular tachycardia (SVT) involves the rapid stimulation of atrial tissue at a rate of 100 to 280 beats/min in adults.* - During SVT, *P waves may not be visible*, especially if there is a 1 : 1 conduction with rapid rates, because the P waves are embedded in the preceding T wave. *SVT may occur in healthy young people, especially women.* - SVT is usually caused by a re-entry mechanism in which one impulse circulates repeatedly throughout the atrial pathway, re-*stimulating the atrial tissue at a rapid rate.* *The term paroxysmal supraventricular tachycardia (PSVT) is used when the rhythm is intermittent.* It is initiated suddenly by a premature complex such as a PAC and terminated suddenly with or without intervention. - *If you see tachycardia without clearly discernible P waves and the QRS is wide, you have to assume VENTRICULAR TACHYCARDIA until proven to be SVT.*

Tachydysrhythmias

- *Tachydysrhythmias are heart rates greater than 100 beats/min.* - *They are a major concern in the adult patient with coronary artery disease (CAD).* Coronary artery blood flow occurs mostly during diastole when the aortic valve is closed and is determined by diastolic time and blood pressure in the root of the aorta. *Tachydysrhythmias are serious because they:* - *Shorten the diastolic time and therefore the coronary PERFUSION time* (the amount of time available for blood to flow through the coronary arteries to the myocardium) - Initially increase cardiac output and blood pressure (However, a continued rise in heart rate decreases the ventricular filling time because of a shortened diastole, decreasing the stroke volume. *Consequently, cardiac output and blood pressure will begin to decrease, reducing aortic pressure and therefore coronary PERFUSION pressure.)* - *Increase the work of the heart, increasing myocardial oxygen demand* The patient with a tachydysrhythmia may have: • Palpitations • Chest discomfort (pressure or pain from myocardial ischemia or infarction) • Restlessness and anxiety • Pale, cool skin • Syncope ("blackout") from hypotension - *Tachydysrhythmias may also lead to heart failure (HF).* Presenting symptoms of heart failure may include dyspnea, lung crackles, distended neck veins, fatigue, and weakness

Ventricular Dysrhythmias *(Worse than Atrial Dysrhythmias? why)*

- *Ventricular dysrhythmias are potentially more life threatening than atrial dysrhythmias because the left ventricle pumps oxygenated blood throughout the body to perfuse vital organs and other tissues.* The most common or life-threatening ventricular dysrhythmias include: • Premature ventricular complexes (PVCs) • Ventricular tachycardia • Ventricular fibrillation • Ventricular asystole

Premature Atrial Complexes (PAC) *(What it is, causes, symptoms)* *(ECG appearance)*

- A *premature atrial complex (contraction) (PAC)* occurs when atrial tissue becomes irritable. *This ectopic focus fires an impulse before the next sinus impulse is due.* - *In order for the premature heartbeat to be called a PAC, it must have an UPRIGHT P wave* - The underlying *rhythm* is regular *EXCEPT* where the PAC occurs. - *The premature P wave may not always be clearly visible because it can be hidden in the preceding T wave.* Examine the T wave closely for any change in shape and compare with other T waves. *A PAC is usually followed by a PAUSE.* The causes of atrial irritability include: • Stress • Fatigue • Anxiety • Inflammation • Infection • Caffeine, nicotine, or alcohol • Drugs such as epinephrine, *sympathomimetics*, amphetamines, digitalis, or anesthetic agents - PACs may also result from myocardial ischemia, hypermetabolic states, electrolyte imbalance, or atrial stretch. *Atrial stretch can result from congestive heart failure*, valvular disease, and pulmonary hypertension with cor pulmonale. - *The patient usually has no symptoms except for possible heart palpitations.* - *No intervention is needed except to treat causes such as heart failure.* - If PACs occur frequently, they may lead to more serious *atrial tachydysrhythmias and therefore may need treatment.* - Administration of prescribed antidysrhythmic drugs may be necessary. Teach the patient measures to manage stress and substances to avoid, such as caffeine and alcohol, that are known to increase atrial irritability.

Atrial depolarization Is reflected by the ___ wave ; AV node delay to allow the ventricles to fill is represented by the ___ segment.

- Atrial depolarization is reflected by the *P wave* on the electrocardiogram (ECG) - AV node delay is reflected in the *PR segment* on the ECG. This slow conduction provides a short delay, allowing the atria to contract and the ventricles to fill. The contraction is known as *atrial kick* and contributes additional blood volume for a greater cardiac output.

Bigeminy

- Bigeminy exists when normal complexes and premature complexes occur *alternately* in a repetitive two-beat pattern, with a pause occurring after each premature complex so complexes occur in pairs.

Bradydysrhythmias (Why it can be beneficial and why it can be detrimental)

- Bradydysrhythmias occur when the heart rate is *less than 60 beats/min.* - These rhythms can also be significant because: - *Myocardial oxygen demand is reduced* from the slow heart rate, which can be beneficial. - *Coronary PERFUSION time may be adequate because of a prolonged diastole*, which is desirable. - Coronary perfusion pressure may decrease if the *heart rate is too slow to provide adequate cardiac output and blood pressure; this is a serious consequence.* - *Therefore the patient may tolerate the bradydysrhythmia well IF the blood pressure (BP) is adequate.* - *If the blood pressure is not adequate, symptomatic bradydysrhythmias may lead to myocardial ischemia or infarction, dysrhythmias, hypotension, and heart failure.* - Once symptomatic, Tx with ATROPINE.

Reading an ECG Strip (each small box represents ___ seconds ; ___ small boxes make up 1 large box, which is ___ seconds)

- Each small block represents *0.04 second.* - *Five small blocks make up one large block, defined by darker bold lines and representing 0.20 second.* - *Five large blocks represent 1 second*, and *30 large blocks represent 6 seconds.*

Ventricular Fibrillation cntd.

- Emergency care for ventricular fibrillation is critical for survival. *When VF begins, the patient becomes faint, immediately loses consciousness, and becomes pulseless and apneic (no breathing).* - There is NO blood pressure, and heart sounds are absent. *Respiratory and metabolic acidosis develop.* Seizures may occur. Within minutes, the pupils become fixed and dilated, and the skin becomes cold and mottled. *Death results without prompt intervention.* - *The priority is to DEFIBRILLATE the patient immediately.* If a defibrillator is not readily available, high-quality *CPR* must be initiated and continued until the defibrillator arrives. *An automated external defibrillator (AED, pictured) is frequently used because it is simple for both medical and lay personnel.*

Sinus Bradycardia (what can cause, symptoms, Assess patient for)

- Excessive vagal *(parasympathetic)* stimulation to the heart causes a *decreased rate of sinus node discharge. (<60 BPM)* - Sinus bradycardia increases coronary PERFUSION time, but it may decrease coronary perfusion pressure. However, myocardial oxygen demand is decreased. - The patient with sinus bradycardia may be *asymptomatic except for the decreased pulse rate.* In many cases, the cause of sinus bradycardia is unknown. *Assess the medication administration record (MAR) to determine if the patient is receiving medications that slow the conduction through the SA or AV node.* *Assess the patient for:* • Syncope ("blackouts" or fainting) • Dizziness and weakness • Confusion • Hypotension • Diaphoresis (excessive sweating) • Shortness of breath • Chest pain - *Remember, DIGOXIN is a POSITIVE INOTROPE and NEGATIVE CHRONOTROPE, meaning it increases contractility of the heart but also slows it down. Do NOT give to a patient who is already bradycardic!*

Atrial Fibrillation: Pathophysiology

- In patients with AF, *multiple rapid impulses from many atrial foci depolarize the atria in a totally disorganized manner at a rate of 350 to 600 times per minute; ventricular response is usually 120 to 200 beats/min.* - The result is a chaotic rhythm with *NO CLEAR P WAVES, no atrial contractions, loss of atrial kick, and an irregular ventricular response (pictured).* - The atria merely quiver in fibrillation (commonly called A fib). *Often the ventricles beat with a rapid rate in response to the numerous atrial impulses.* The rapid and irregular ventricular rate decreases ventricular filling and *reduces cardiac output.* This alteration in cardiac function allows for blood to pool, placing the patient at risk for *CLOTTING concerns such as DVT or PE.*AF is frequently associated with underlying cardiovascular disease such as hypertension, HF, and CAD. - *As AF progresses, cardiac output decreases by as much as 20% to 30%*

Atrial Dysrhythmias (3 types) *(Results in changes of the __ Wave)*

- In patients with atrial dysrhythmias, the focus of impulse generation shifts away from the sinus node to the atrial tissues. - The shift changes the axis (direction) of atrial depolarization, *resulting in a P-wave shape that differs from normal P waves.* The most common atrial dysrhythmias are: • Premature atrial complexes • Supraventricular tachycardia • Atrial fibrillation *P wave is always the problem in Atrial Dysrhythmias!*

Sinus Tachycardia S/S (Why would it be compensatory?)

- In some cases, sinus tachycardia is a *compensatory response* to decreased cardiac output or blood pressure, as occurs in dehydration, hypovolemic shock, myocardial infarction (MI), infection, and heart failure. *Assess patients for signs and symptoms of hypovolemia and dehydration, including increased pulse rate, decreased urinary output, decreased blood pressure, and dry skin and mucous membranes.* - The desired outcome is to decrease the heart rate to normal levels by treating the underlying cause. *Remind the patient to remain on bedrest if the tachycardia is causing hypotension or weakness.* - Teach the patient to avoid substances that increase cardiac rate, including *caffeine, alcohol, and nicotine.* Help patients develop stress-management strategies or refer the patient to a mental health professional.

Premature ventricular complexes (PVCs) What is the drug of choice to administer?

- Premature ventricular complexes (PVCs), also called premature ventricular contractions, *result from increased irritability of ventricular cells and are seen as early ventricular complexes followed by a PAUSE.* - When multiple PVCs are present, the QRS complexes may be unifocal or uniform, meaning that they are of the same shape (Fig. 34-12A), or multifocal or multiform, meaning that they are of different shapes (Fig. 34-12B). - *PVCs frequently occur in repetitive rhythms, such as bigeminy (two), trigeminy (three), and quadrigeminy (four).* Two sequential PVCs are a pair, or couplet. Three or more successive PVCs are usually called nonsustained ventricular tachycardia (NSVT).

PVC causes

- Premature ventricular contractions are common, and their frequency increases with age. - They may be insignificant or may occur with problems such as myocardial infarction, chronic heart failure, chronic obstructive pulmonary disease (COPD), and anemia. PVCs may also be present in patients with hypokalemia or hypomagnesemia. - Sympathomimetic agents, anesthesia drugs, stress, nicotine, caffeine, alcohol, infection, or surgery can also cause PVCs, especially in older adults. Postmenopausal women often find that caffeine causes palpitations and PVCs. - The patient may be asymptomatic or experience palpitations or chest discomfort caused by increased stroke volume of the normal beat after the pause. - *Peripheral pulses may be diminished or absent with the PVCs themselves because the decreased stroke volume of the premature beats may decrease peripheral PERFUSION.*

SVT Interprofessional Collaborative Care (Stimulating a *Vagal reflex*)

- Signs and symptoms depend on the duration of the SVT and the rate of the ventricular response. *In patients with a SUSTAINED rapid ventricular response, assess for palpitations, chest pain, weakness, fatigue, shortness of breath, nervousness, anxiety, hypotension, and syncope.* - *Cardiovascular deterioration may occur if the rate does not sustain adequate blood pressure.* In that case, SVT can result in angina, heart failure, and cardiogenic shock. - *With a NONSUSTAINED or slower ventricular response, the patient may be asymptomatic except for occasional palpitations.* - If SVT occurs in a healthy person and stops on its own, no intervention may be needed other than eliminating identified causes. If it continues, the patient should be studied in the electrophysiology study (EPS) laboratory. - The preferred treatment for recurrent SVT is radiofrequency *catheter ablation.* - In sustained SVT with a rapid ventricular response, the desired outcomes of treatment are to decrease the ventricular response, convert the dysrhythmia to a sinus rhythm, and treat the cause. - In *carotid sinus massage,* the health care provider massages over one carotid artery for a few seconds, observing for a change in cardiac rhythm. This intervention causes vagal stimulation, slowing SA and AV nodal conduction. Prepare the patient for the procedure. Instruct him or her to turn the head slightly away from the side to be massaged and observe the cardiac monitor for a change in rhythm. An ECG rhythm strip is recorded before, during, and after the procedure. After the procedure, assess vital signs and the level of consciousness. Complications include bradydysrhythmias, asystole, ventricular fibrillation (VF), and cerebral damage. *Because of these risks, carotid massage is not commonly performed. A defibrillator and resuscitative equipment must be immediately available during the procedure.* - To stimulate a *VAGAL (PNS) reflex*, the health care provider instructs the patient to bear down as if straining to have a bowel movement. *Assess the patient's heart rate, heart rhythm, and blood pressure. Observe the cardiac monitor and record an ECG rhythm strip before, during, and after the procedure to determine the effect of therapy.* - Drug therapy is prescribed for some patients to convert SVT to a normal sinus rhythm (NSR). *Adenosine (Adenocard)* is used to terminate the acute episode and given rapidly (over several seconds) followed by a normal saline bolus.

Sinus Tachycardia (Stimulated by what?)

- Sympathetic nervous system (SNS) stimulation or vagal (parasympathetic) inhibition results in an *increased rate of SA node discharge*, which increases the heart rate. *When the rate of SA node discharge is more than 100 beats/min, the rhythm is called sinus tachycardia.* - *From age 10 years to adulthood, the heart rate normally does not exceed 100 beats/min except in response to activity* and then usually does not exceed 160 beats/min. Rarely does the heart rate reach 180 beats/min. - *Sinus tachycardia INITIALLY increases cardiac output and blood pressure.* However, continued increases in heart rate decrease coronary PERFUSION time, diastolic filling time, and coronary PERFUSION pressure while increasing myocardial oxygen demand. - *The HR is 115 BPM in this example.* 300/2.6= *115 BPM*

Estimating ventricular rate using an ECG strip *(IF the rhythm is IRREGULAR)*

-Pictured: *Each segment between the dark lines (above the monitor strip) represents 3 seconds when the monitor is set at a speed of 25 mm per second.* - To estimate the ventricular rate, *count the QRS complexes in a 6-second strip and multiply that number by 10 to estimate the rate for 1 minute.* - In this example, there are 9 QRS complexes in 6 seconds. Therefore the heart rate can be estimated to be 90 beats/min.

Electrocardiographic Complexes, Segments, and Intervals (How long is the *PR interval* and *QRS complex* normally? ) (What is the QT interval?)

- The *P wave is a deflection representing atrial depolarization.* The shape of the P wave may be a positive, negative, or biphasic (both positive and negative) deflection, depending on the lead selected. *When the electrical impulse is consistently generated from the sinoatrial (SA) node, the P waves have a consistent shape in a given lead.* If an impulse is then generated from a different (ectopic) focus, such as atrial tissue, the shape of the P wave changes in that lead, indicating that an ectopic focus has fired. - The *PR segment is the isoelectric line from the end of the P wave to the beginning of the QRS complex, when the electrical impulse is traveling through the atrioventricular (AV) node, where it is delayed.* It then travels through the ventricular conduction system to the Purkinje fibers. - The *PR interval is measured from the beginning of the P wave to the end of the PR segment.* It represents the time required for atrial depolarization, the impulse delay in the AV node, and the travel time to the Purkinje fibers. It normally measures from *0.12 to 0.20 second (five small blocks).* - The *QRS complex represents ventricular depolarization.* The shape of the QRS complex depends on the lead selected. The Q wave is the first negative deflection and is not present in all leads. When present, it is small and represents initial ventricular septal depolarization. When the Q wave is abnormally present in a lead, it represents myocardial necrosis (cell death). The R wave is the first positive deflection. It may be small, large, or absent, depending on the lead. The S wave is a negative deflection following the R wave and is not present in all leads. - The *QRS duration represents the time required for depolarization of both ventricles.* It is measured from the beginning of the QRS complex to the J point (the junction where the QRS complex ends and the ST segment begins). *It normally measures from 0.04 to 0.12 second (up to three small blocks).* - The *ST segment is normally an isoelectric line and represents early ventricular repolarization.* It occurs from the J point to the beginning of the T wave. *Its length varies with changes in the heart rate, the administration of medications, and electrolyte disturbances.* - The *T wave follows the ST segment and represents ventricular repolarization.* It is usually positive, rounded, and slightly asymmetric. T waves may become tall and peaked; inverted (negative); or flat as a result of myocardial ischemia, potassium or calcium imbalances, medications, or autonomic nervous system effects. - The U wave, when present, follows the T wave and may result from slow repolarization of ventricular Purkinje fibers. It is of the same polarity as the T wave, although generally it is smaller. It is not normally seen in all leads and is more common in lead V3. An abnormal U wave may suggest an electrolyte abnormality (particularly hypokalemia) or other disturbance. Correct identification is important so it is not mistaken for a P wave. If in doubt, notify the primary health care provider and request that a potassium level be obtained. - The *QT interval represents the total time required for ventricular depolarization and repolarization.* The QT interval is measured from the *beginning of the Q wave to the end of the T wave.* This interval varies with the patient's age and gender and changes with the heart rate, *lengthening with slower heart rates and shortening with faster rates.* It may be prolonged by certain medications, electrolyte disturbances, or subarachnoid hemorrhage. *A prolonged QT interval may lead to a unique type of ventricular tachycardia called torsades de pointes.*

Sinus arrhythmia

- The heart rate increases slightly during inspiration and decreases slightly during exhalation. This irregular rhythm is frequently observed in healthy adults. - *Sinus arrhythmia has all the characteristics of NSR except for its irregularity.* The PP and RR intervals vary, *with the difference between the shortest and the longest intervals being greater than 0.12 second (three small blocks)* • Rate: Atrial and ventricular rates between 60 and 100 beats/min • Rhythm: *Atrial and ventricular rhythms irregular,* with the shortest PP or RR interval varying at least 0.12 second from the longest PP or RR interval • P waves: *One P wave before each QRS complex; consistent configuration* • PR interval: Normal, constant • QRS duration: Normal, constant

Atrial Fibrillation: Planning and interventions

- The priority collaborative problems for most patients with atrial fibrillation are: 1. Potential for embolus formation due to irregular cardiac rhythm 2. Potential for heart failure due to altered conduction pattern - Assess for prior history of AF or other dysrhythmias - With increased heart rate, cardiac output decreases, which can create dyspnea - Definitive diagnosis occurs by obtaining a 12-lead ECG. AF is classified into five categories based on length of time in the rhythm: paroxysmal, persistent, long-standing persistent, permanent, and nonvalvular - The expected outcome is that the patient will remain free of embolus formation by restoring regular cardiac conduction. - Traditional interventions for AF include antidysrhythmic drugs to slow the ventricular conduction or to convert the AF to normal sinus rhythm (NSR).

12 lead ECG (How many on the limbs and how many on the chest and where?)

- The standard 12-lead ECG consists of 12 leads (or views) of the heart's electrical activity. - Six of the leads are called *limb leads* because the electrodes are placed on the four extremities in the frontal plane. - The remaining six leads are called *chest (precordial) leads* because the electrodes are placed on the chest in the horizontal plane. With a 12-lead ECG, four leads are placed on the limbs, and six are placed on the chest, eliminating the need to move any electrodes about the chest *(10 total)*

Ventricular Asystole *(Do NOT defibrillate? why?)* *(do what instead?)*

- Ventricular asystole, sometimes called ventricular standstill, is the *complete absence of any ventricular rhythm.* - There are no electrical impulses in the ventricles and therefore *NO ventricular depolarization, no QRS complex, no contraction, no cardiac output, and no PERFUSION to the rest of the body.* - *The patient in ventricular asystole has no pulse, respirations, or blood pressure. The patient is in full cardiac arrest!* (When cardiac arrest occurs, cardiac output stops) - *Do NOT defibrillate ventricular asystole.* In ventricular asystole, no electrical impulses are present to disrupt. *Instead, perform CPR.*

Ventricular Fibrillation

- Ventricular fibrillation (VF), sometimes called V fib, is the result of electrical chaos in the ventricles and is life threatening! - *The ventricles merely quiver, consuming a tremendous amount of oxygen.* - There is *NO cardiac output or pulse and therefore no cerebral, myocardial, or systemic perfusion.* - This rhythm is rapidly fatal if not successfully ended within *3 to 5 minutes.*

Ventricular tachycardia (VT)

- Ventricular tachycardia (VT), sometimes referred to as V tach, occurs with *repetitive firing of an irritable ventricular ectopic focus, usually at a rate of 140 to 180 beats/min or more.* - VT may result from increased automaticity or a re-entry mechanism. *It may be intermittent (nonsustained VT) or sustained, lasting longer than 15 to 30 seconds.* (WIDE QRS) - The sinus node may continue to discharge independently, depolarizing the atria but not the ventricles, although *P waves are seldom seen in sustained VT.* - *In patients who go into cardiac arrest, VT is commonly the initial rhythm before deterioration into ventricular fibrillation (VF) as the terminal rhythm!*

Atrioventricular Blocks

- When *supraventricular impulses are excessively delayed or totally blocked in the AV node or ventricular conduction system, leading to Ventricular depolarization and QRS complexes are delayed or blocked* *1st degree* - All sinus impulses eventually reach ventricles *(PR interval is >0.20 seconds)* *2nd degree* - Some sinus impulses reach ventricles and some do not. *(Some QRS complexes are absent)* *3rd degree (complete heart block)* - None of the sinus impulses reach the ventricles, depolarized by a second independent pacemaker. *(P wave and QRS complex are completely out of sync)*

Automaticity

- is the ability of cardiac cells to generate an electrical impulse *spontaneously and repetitively.* - *Normally only the sinoatrial (SA) node can generate an electrical impulse. However,* under certain conditions, such as myocardial ischemia (decreased blood flow), electrolyte imbalance, hypoxia, drug toxicity, and infarction (cell death), *any cardiac cell may produce electrical impulses independently and create dysrhythmias.* Disturbances in automaticity may involve either an increase or a decrease in pacing function.

The nurse is caring for a patient with acute coronary syndrome (ACS) and atrial fibrillation who has a new prescription for metoprolol (Toprol). Which monitoring is essential when administering the medication? ST segment Heart rate Troponin Myoglobin

Heart rate - *The monitoring of the patient's heart rate is essential. The effects of metoprolol are to decrease heart rate, blood pressure, and myocardial oxygen demand.* - *ST segment ELEVATION is consistent with MI*; it does not address monitoring of metoprolol. - *Elevation in troponin is consistent with a diagnosis of MI, but does not address needed monitoring for metoprolol.* - Elevation in *myoglobin* is consistent with *myocardial injury in ACS*, but does not address needed monitoring related to metoprolol.

The nurse is caring for a patient with atrial fibrillation (AF). In addition to an antidysrhythmic, what medication does the nurse plan to administer? Heparin Atropine Dobutamine Magnesium sulfate

Heparin - The nurse plans to administer heparin in addition to the antidysrhythmic. *AF is the loss of coordinated atrial contractions that can lead to pooling of blood, resulting in thrombus formation.* The patient is at high risk for pulmonary and systemic embolism. - Heparin and other anticoagulants (e.g., enoxaparin [Lovenox], warfarin [Coumadin], and novel oral anticoagualants, when nonvalvular, such as dabigatran [Pradaxa], rivaroxaban [Xarelto], apixaban [Eliquis], or edoxaban [Savaysa]) are used to prevent thrombus development in the atrium, leading to the risk of embolization (i.e., stroke). - *Atropine is used to treat bradycardia* and not rapid heart rate associated with AF. - *Dobutamine is an inotropic agent used to improve cardiac output*; it may cause tachycardia, thereby worsening atrial fibrillation. - Although electrolyte levels are monitored in clients with dysrhythmia, magnesium sulfate is not used unless depletion is noted.

The nurse receives a report that a patient with a pacemaker has experienced *loss of capture.* Which situation is consistent with this? The pacemaker spike falls on the T wave. Pacemaker spikes are noted, but no P wave or QRS complex follows. The heart rate is 42 beats/min, and no pacemaker spikes are seen on the rhythm strip. The patient demonstrates hiccups.

Pacemaker spikes are noted, but no P wave or QRS complex follows. - *Loss of capture occurs when the pacing stimulus (spike) is NOT followed by the appropriate response, either P wave or QRS complex, depending on placement of the pacing electrode.* - Pacemaker spikes falling on the T wave indicate improper sensing. *A heart rate of 42 beats/min with no pacemaker spikes seen on the rhythm strip indicates* *FAILURE TO PACE or sense properly.* - *Demand pacing (Synchronous)* would cause the pacemaker to *intervene* with electrical output when the heart rate falls below the set rate. Although the set rate is not given, this heart rate indicates profound bradycardia. - *Hiccups may indicate stimulation of the chest wall or diaphragm from wire perforation.*

The nurse is caring for a patient with heart rate of 143 beats/min. For which manifestations does the nurse observe? *Select all that apply.* Palpitations Increased energy Chest discomfort Flushing of the skin Hypotension

Palpitations Chest discomfort Hypotension - Tachycardia is a heart rate greater than 100 beats/min; the patient with a tachydysrhythmia may have *palpitations, chest discomfort (pressure or pain from myocardial ischemia or infarction), restlessness and anxiety, pale cool skin, and syncope ("blackout") from hypotension.* - Chest discomfort and palpitations may occur because decreased time for diastole results in lower perfusion through the coronary arteries to the myocardium. - *Hypotension results from decreased time for ventricular filling, secondary to shortened diastole, and therefore reduced cardiac output and blood pressure.* - Reduced cardiac output and possible development of heart failure will cause fatigue. - In this situation, the patient will have pale, cool skin and not flushing of the skin. Also, reduced cardiac output and possible development of heart failure will cause fatigue and not increased energy.

A patient admitted after using crack cocaine develops ventricular fibrillation. After determining unresponsiveness, which action does the nurse take next? Prepare for defibrillation. Establish IV access. Place an oral airway and ventilate. Start cardiopulmonary resuscitation (CPR).

Prepare for defibrillation. - Defibrillating is the priority next action before any other resuscitative measures, according to advanced cardiac life support protocols. - *After immediate defibrillation, establish IV access, place an oral airway, and ventilate.* - CPR will be started after unsuccessful defibrillation.