Cardiac Arrhythmia

Definition: The pumping action of the heart is coordinated by an electrical system within the heart tissue. An irregularity in this electrical system is called an arrhythmia, or heart rhythm disorder.

Causes: -Congenital. -Myocardial ischemia. -MI. -Organic heart disease. -Drugs effects and toxicity. -Conductive tissue deterioration. -Electrolyte imbalance. -Acid-base imbalances. -Cellular hypoxia.

Pathophysiology: -Results from a disturbance in conductivity. -Heart rate and rhythm are altered, reducing cardiac output. Assessment finding: -Palpitations. -Chest pain. -Weakness, fatigue.

-Irregular heart rhythm. -Bradycardia or tachycardia. -Dizziness. -Hypotension. -Altered level of consciousness. -Pallor. -Nausea, vomiting. -Cold skin.

Possible diagnostic findings: * ECG: changes in heart rate, rhythm. * Blood chemistry: electrolyte imbalance. Nursing intervention: Monitor pulse for irregular pattern or abnormally rapid or slow rate. Observe for arrhythmias if the patient is receiving continuous cardiac monitoring. Assess cardiovascular, respiratory, and neurovascular status. Initiate cardiopulmonary resuscitation (CPR), if indicated, until other advanced cardiac life support measures are available and successful. Perform defibrillation early for ventricular tachycardia and ventricular fibrillation.

Administer medications, oxygen, and I.V fluids, as needed. Prepare for procedures, such as cardioversion or pacemaker insertion, if indicated. Monitor for predisposing factors (such as fluid and electrolyte imbalance) and signs of drug toxicity, especially digoxin. * Monitor and record vital signs. * Maintain prescribed diet. * Maintain bed rest, until patient is stable. * Provide support to the patient and family.

Characteristics of normal rhythm include: -Ventricular and atrial rates of 60 to 100 beats/ minute. -Regular and uniform QRS complexes and P waves. -PR interval of 0.12 to 0.2 second. -QRS duration <0.12 second.

Causes -Fever, anxiety, pain, dehydration, may also left ventricular failure, hyperthyroidism, anemia, hypovolemia, pulmonary embolism, and anterior wall MI. -May also occur with atropine, epinephrine, alcohol, caffeine, and nicotine use.

Treatment -Correction of underlying cause. -Beta and calcium blockers.

-Increased intracranial pressure, increased vagal Causes: -Normal, in well-conditioned heart, as in an athlete. -Increased intracranial pressure, increased vagal tone due to straining during defecation, vomiting, intubation, mechanical ventilation, sick sinus syndrome, hypothyroidism, inferior wall MI. -Morphine use.

Treatment: -Correction of underlying cause. -Administration of atropine. -Temporary or permanent pacemaker. -Dopamine or epinephrine infusion.

Causes: -Heart failure (HF), tricuspid or mitral valve disease, pulmonary embolism, inferior wall MI and carditis. -Digoxin toxicity.

Treatment: -If patient is unstable with a ventricular rate >150 b/m, immediate cardioversion. If patient is stable, drug therapy may include calcium blockers, or antiarrhythmics. -Anticoagulation therapy (heparin).

Causes: -H.F., COPD, thyrotoxicosis, Pericarditis, (IHD), sepsis, pulmonary embolism, (RHD), hypertension, mitral stenosis, complication of coronary bypass or valve replacement surgery. - Digoxin use.

Treatment: -If patient is unstable with a ventricular rate >150 b/m, immediate cardioversion. - If patient is stable, drug therapy may include calcium and beta blockers, or antiarrhythmics. -Anticoagulation therapy (heparin).

Causes: Myocardial ischemia or infarction, untreated ventricular tachycardia, hyperkalemia , hypercalcemia , Hypothermia, Digoxin or epinephrine toxicity.

Treatment: Administration of epinephrine ,if ineffective magnesium sulfate is given.

Ventricular tachycardia

Causes: Myocardial ischemia infarction , Coronary artery disease , Rheumatic heart disease, Heart failure , Hypokalemia ; Hypercalcemia, Digoxin toxicity, Anxiety.

Treatment: Initiate cardiopulmonary resuscitation and administration of epinephrine.

Correction of underlying cause Treatment Causes Arrhythmia And Feature Correction of underlying cause Possibly atropine if severe bradycardia develops and the patient is symptomatic Cautious use of digoxin and beta –adrenergic blockers May be seen in a healthy person Inferior wall MI, or Ischemia, hypothyroidism, hypokalemia , hyperkalemia. Digoxin toxicity First – degree AV block Atrial and ventricular rhythms regular PR interval > 0.20 second QSR complex normal

Treatment of underlying cause Atropine for symptomatic Bradycardia Discontinuation of digoxin . Inferior wall MI ,cardiac surgery acute rheumatic fever ,and vagal stimulation Digoxin toxicity Second- degree AV block Atrial rhythm regular Ventricular rhythm irregular Atrial rate exceeds ventricular rate PR interval progressively longer

Atropine , dopamine , or epinephrine for symptomatic bradycardia Temporary or permanent pacemaker Inferior or anterior wall MI , congenital abnormality , rheumatic fever ,hypoxia , postoperative complication of mitral valve replacement Digoxin toxicity Third – degree AVblock Atrial rhythm regular Ventricular rate slow and rhythm regular No relation between P waves and QRS complex No stable PR interval QRS interval normal or wide PR interval varies P wave may be covered in QRS complexes or T wave QSR complex normal

Possible surgical intervention Complications: Stroke Death MI Hypotension Shock Heart failure Possible surgical intervention -Pacemaker insertion -Catheter ablation therapy

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