Care of Patient With Dysrhythmias Dr. Belal Hijji, RN, Phd October 19 &24, 2011
Learning Outcomes At the end of this lecture, students will be able to: • Describe the normal electrical conduction of the heart. • Discuss the characeristics of various types of sinus node and ventricular dysrhythmias. • Describe the nursing management of a patient with dysrhythmias.
Introduction • For the heart to perform efficiently as a pump, it should have a regular rate and rhythm. Without this, the heart is considered dysrhythmic, which could be a dangerous condition. • Dysrhythmias are disorders of the formation or conduction (or both) of the electrical impulse within the heart that can cause disturbances of the heart rate, rhythm, or both. • Dysrhythmias may initially be evidenced by the hemodynamic effect they cause (decreased blood pressure). • Dysrhythmias are diagnosed by analyzing the ECG waveform. They are named according to the site of origin of the impulse and the mechanism of formation or conduction involved. For example, an impulse that originates in the sinoatrial (SA) node and that has a slow rate is called sinus bradycardia.
FIGURE 1 The heart conducts electrical activity, which the ECG measures and shows. The configurations of electrical activity displayed on the ECG vary depending on the lead of the ECG and on the rhythm of the heart. Therefore, the configuration of a normal rhythm tracing from lead I differs from the configuration of a normal rhythm tracing from lead II, lead II differs from lead III. The same is true for abnormal rhythms and cardiac disorders. To make an accurate assessment of the heart’s electrical activity, the ECG needs to be evaluated from every lead. Here the different areas of electrical activity are identified by color.
Normal Electrical Conduction • The electrical impulse, occurring at a range between 60 and 100 times/ minute (adult) , that stimulates the cardiac muscle originates in the sinus node (SA node). • The impulse quickly travels from the sinus node to the atrioventricular (AV) node (Previous slide). • The electrical stimulation of the atria causes them to contract. The structure of the AV node slows the electrical impulse, which allows time for the atria to contract and fill the ventricles with blood before the electrical impulse travels very quickly through the bundle of His to the right and left bundle branches and the Purkinje fibers. • The electrical stimulation of the ventricles causes them to contract (systole). The ventricular cells electrically repolarize (relax) and the ventricles then relax (diastole). The process from sinus node electrical impulse generation (depolarisation) through ventricular repolarization completes the electromechanical circuit, and the cycle begins again.
Types of Dysrhythmias • Dysrhythmias include sinus node, atrial, junctional, and ventricular dysrhythmias and their various subcategories. • Due to time constraints, subsequent slides will focus on sinus node and ventricular dysrhythmias.
Sinus Node Dysrhythmias • Sinus Bradycardia.Sinus bradycardia (Next slide)occurs when the sinus node creates an impulse at a slower-than-normal rate. Causes include lower metabolic needs (eg, sleep, athletic training, hypothermia, hypothyroidism), vagal stimulation (eg, from vomiting, suctioning, severe pain, extreme emotions), medications (beta-blockers), increased intracranial pressure, and myocardial infarction (MI). The treatment of choice of sinus bradycardia is atropine, 0.5 to 1.0 mg given rapidly as an intravenous (IV) bolus. Sinus bradycardia characteristics are: • Ventricular and atrial rate: Less than 60 in the adult • Ventricular and atrial rhythm: Regular • QRS shape and duration: Usually normal, but may be regularly abnormal
P wave: Normal and consistent shape; always in front of QRS • PR interval: Consistent interval between 0.12 and 0.20 seconds • P: QRS ratio: 1:1. FIGURE 2 Sinus bradycardia in lead II.
Sinus Tachycardia.Sinus tachycardia (See below) occurs when the sinus node creates an impulse at a faster-than-normal rate. It may be caused by acute blood loss, anemia, shock, hypervolemia, hypovolemia, congestive heart failure, pain, fever, exercise, or anxiety. Treatment is through abolishing the cause. Calcium channel blockers (Nifedipine) and beta-blockers (Atenolol) can quickly reduce heart rate . The characteristics of sinus tachycardia are: • Ventricular and atrial rate: Greater than 100 in the adult • Ventricular and atrial rhythm: Regular • QRS shape and duration: Usually normal, but may be regularly abnormal • P wave: Normal and consistent shape; always in front of the QRS, but may be buried in the preceding T wave • PR interval: Consistent interval between 0.12 and 0.20 seconds • P: QRS ratio: 1:1
Sinus Arrhythmia. Sinus arrhythmia (See below) occurs when the sinus node creates an impulse at an irregular rhythm; the rate usually increases with inspiration and decreases with expiration. Sinus arrhythmias does not cause significant hemodynamic effect and usually it is not treated. The ECG criteria for sinus arrhythmia are: • Ventricular and atrial rate: 60 to 100 in the adult • Ventricular and atrial rhythm: Irregular • QRS shape and duration: Usually normal, but may be regularly abnormal • P wave: Normal and consistent shape; always in front of QRS • P-R interval: Consistent interval between 0.12and 0.20 seconds • P: QRS ratio: 1:1
Ventricular Dysrhythmias • Premature Ventricular Complex (PVC).PVC is an impulse that starts in a ventricle and is conducted through the ventricles before the next normal sinus impulse. PVCs can occur in healthy people who use caffeine, nicotine, or alcohol. Other causes include cardiac ischemia or infarction, increased workload on the heart (eg, exercise, fever, hypervolemia, heart failure, tachycardia), digitalis toxicity, or hypokalemia. • In the absence of disease, PVCs are not serious. In the patient with an acute MI, PVCs may indicate the need for more aggressive therapy. • Initial treatment includes correcting the cause, if possible. Lidocaine (Xylocaine) is the medication most commonly used for immediate, short-term therapy. No need for long-term pharmacotherapy for only PVCs.
Ventricular Tachycardia (VT).VT (See below) is defined as three or more PVCs in a row, occurring at a rate exceeding 100 beats per minute. The causes are similar to those for PVC. VT is usually associated with CAD and is an emergency because the patient is usually unresponsive and pulseless. In an unconscious and pulseless patient, defibrilation is the treatment of choice. VT characteristics are: • Ventricular and atrial rate: Ventricular rate is 100 to 200 beats per minute; atrial rate depends on the underlying rhythm (eg, sinus rhythm) • Ventricular and atrial rhythm: Usually regular; atrial rhythm may be regular. • QRS shape and duration: Duration is 0.12 seconds or more; bizarre, abnormal shape.
Ventricular Fibrillation. Ventricular fibrillation is a rapid and disorganized ventricular rhythm that causes ineffective quivering [trembling, shivering] of the ventricles. Its causes are the same as for VT, untreated or unsuccessfully treated VT, or electrical shock. Patient’s heart beat is inaudible, pulse impalpable, and absent respirations. Cardiac arrest and death are imminent if ventricular fibrillation is not immediately corrected through defibrillation. Ventricular fibrillation has the following characteristics: • Ventricular rate: Greater than 300 per minute • Ventricular rhythm: Extremely irregular • QRS shape and duration: Irregular, unrecognizable QRS complexes
Nursing Management of a Patient With Dysrhythmias • Assessment: • Obtain health history to identify any previous occurrences of decreased cardiac output, including syncope (fainting), fatigue, lightheadedness, dizziness, chest discomfort, and palpitations. • Identify coexisting conditions that may be the cause of the dysrhythmia (eg, heart disease, chronic obstructive pulmonary disease). • Review medications as some (Digoxin) can cause dysrhythmias. • Conducts a physical assessment to observe for signs of diminished cardiac output (changes in LOC. Inspect the skin (may be pale and cool). Assess signs of fluid retention (neck vein distention; crackles and wheezes in the lungs). • Auscultates for extra heart sounds (S3 and S4). Measure blood pressure, and determines pulse pressures. A declining pulse pressure indicates reduced cardiac output.
Nursing Management of a Patient With Dysrhythmias • Nursing Diagnoses: • Decreased cardiac output • Anxiety related to fear of the unknown • Deficient knowledge about the dysrhythmia and its treatment • Planning and Goals • Eradication or reduction in the incidence of the dysrhythmia (by decreasing contributory factors) • Maintenance of cardiac output • Minimising anxiety • Acquiring knowledge about the dysrhythmia and its treatment
Nursing Management of a Patient With Dysrhythmias • Nursing Interventions: • Monitoring and managing dysrhythmias • Record BP, HR and rhythm, rate and depth of respirations, and breath sounds to determine the dysrhythmia’s hemodynamic effect. • Ask patients about episodes of lightheadedness, dizziness, or fainting. • Obtain a 12-lead ECG to continuously monitor the patient and to track the dysrhythmia. • Administer antiarrhythmic medications as prescribed. • Assess for factors that contribute to the dysrhythmia (eg, caffeine, stress, nonadherence to the medication regimen) and assist the patient in making lifestyle changes that adress these issuses.
Nursing Management of a Patient With Dysrhythmias • Nursing Interventions (Continued…..): • Minimising anxiety • At the time of dysrhythmic event, maintain a calm and reassuring attitude to foster a trusting relationship with the patient and assists in reducing anxiety. • Promote a sense of confidence in living with a dysrhythmia. For example, while administering a medication at a dysrhythmia event and it begins to reduce the incidence of dysrhythmia, communicate that information to the patient.
Nursing Management of a Patient With Dysrhythmias • Nursing Interventions (Continued…..): • Teaching patient self-care • Present the information in terms that are understandable and in a manner that is not frightening or threatening. • Explain the importance of taking medications regularly to maintain therapeutic serum levels of antiarrhythmic agents • If dysrhythmia is potentially lethal, establish with the patient and family a plan of action to take in case of an emergency.
Nursing Management of a Patient With Dysrhythmias • Evaluation: The patient • Maintains cardiac output • Demonstrates HR, BP, RR, and LOC within normal ranges • Demonstrates no or decreased episodes of dysrhythmia • Has reduced anxiety • Expresses a positive attitude about living with the dysrhythmia • Expresses confidence in ability to take appropriate actions in an emergency • Expresses understanding of the dysrhythmia and its treatment • Explains the dysrhythmia and its effects • Describes the medication regimen and its rationale • Explains the need for therapeutic serum level of the medication • Describes a plan to eradicate or limit factors that contribute to the occurrence of the dysrhythmia • States actions to take in the event of an emergency