Cardiac Dysrhythmias NURS 2106 Dysrhythmias (arrhythmias): Most common complication post MI Disturbance of rate, rhythm or conduction of electrical impulses within the heart Prompt assessment of dysrhythmias and the patient’s response to the rhythm is critical Classifications of arrhythmias: Sites: o SA node (sinus rhythm) o Atrial (atrial rhythms) o AV node (nodal or junctional rhythm) o Ventricles (ventricular rhythms) Type: o Flutter o Fibrillation o Block Prognosis: Minor – no immediate concern Major – reduction of efficiency of the heart Lethal – requires immediate treatment or resuscitation, death producing Dysrhythmias symptoms: Some dysrhythmias no symptoms Some dysrhythmias life threatening (sudden collapse, death) Typical symptoms: o Dizziness o Weakness o Decreased exercise tolerance o Shortness of breath o Fainting o Palpitations or “heart has skipped a beat” Common causes of dysrhythmias: Cardiac causes o Accessory pathways, conduction defects o Cardiomyopathy, heart failure o Myocardial cell degeneration (ischemia, injury, infarction) o Valve disease Other conditions o Acid-base imbalances o Electrolyte disturbances o Caffeine, tobacco, alcohol o Drug effects (antidysrhythmia, stimulants, beta-blockers) o Emotional crisis, herbal supplements, connective tissue disorders o Hypoxia, shock o Metabolic conditions (thyroid dysfunction) o Near-drowning, poisoning 2 Sinus Bradycardia Identifying EKG characteristics: Rate: < 60 beats a minute Rhythm: Regular P waves: Normal and precede each QRS PR interval: Normal range (0.12 – 0.20) QRS: Normal (< 0.12) Etiology: May be normal in physically conditioned adults and during sleep Increased vagal tone (Valsalva maneuver, endotracheal suctioning, vomiting, gagging) Medication effect (narcotics, cardiac glycoside, beta blockers, calcium channel blockers) Pathology (hypothermia, hypothyroidism, increased intracranial pressure, obstructive jaundice, MI--inferior wall MI involves right coronary artery). Ischemia of sinus node slows rate. Clinical significance: May be asymptomatic. Symptoms are associated with decreased cardiac output: o Hypotension, dizziness, syncope o Pale, cool skin o Weakness o Confusion or disorientation o Shortness of breath o Angina o Decreased urinary output Treatment: Treat only is symptomatic Atropine IVP (0.5 – 1 mg) If due to medication discontinue or reduce dose Pacemaker may be required Nursing implications: Assess for signs and symptoms of decreased cardiac output Observe for premature ventricular contractions (PVCs) or other ectopic beats Assist with medical treatment: atropine if ordered, preparation for pacemaker insertion 3 Sinus Tachycardia Identifying EKG characteristics: Rate: > 100 beats a minute (usually 101 – 200 bpm) Rhythm: Regular P waves: Present, normal in shape; may not be clearly identified if encroach on preceding T waves PR interval: Normal QRS: Normal Etiology: Physiological response to exercise, stress, fever, caffeine, pain, emotion, hyperthyroidism, hypoglycemia Treatment with medications such as adrenergics, anticholinergics, amphetamines, caffeine, nicotine, cocaine Compensatory mechanism for decreased cardiac output (heart failure, hypoxia, hypotension, anemia, hypovolemia) In acute MI occurs more often with anterior MI because of left ventricular failure Clinical significance: May be asymptomatic or may feel a “fluttering” in the chest Cardiac output may diminish due to decreased chamber filling time resulting in dizziness, dyspnea, hypotension, syncope Increased myocardial oxygen consumption may lead to angina or increase in infarct size in MI Treatment: Determined by underlying cause o Antipyretics to treat fever o Analgesics to treat pain o Treatment for hypovolemia or hypervolemia, hypoxia o Medications: Beta-blockers, calcium channel blockers, tranquilizes, antianxiety agents, IV adenosine (Adenocard) Adenocard may cause brief asystole. Monitor EKG continuously. Nursing implications: Assess for possible causes Administer medications as ordered 4 Atrial Flutter Identifying EKG characteristics: Rate: Atrial rate: 250 – 350 bpm. Ventricular rate: Varies o Ventricular rate depends on number of impulses that are conducted through AV node---2:1, 3:1, 4:1. Rhythm: Atrial is regular. Ventricular may be regular or irregular. P waves: No normal P wave. Saw tooth-shaped flutter waves. PR interval: Unable to measure QRS: Usually normal Etiology: CAD, hypertension, mitral valve disorder, pulmonary embolus, COPD, cor pulmonale, cardiomyopathy, hyperthyroidism, medications (digoxin, quinidine, epinephrine) Clinical significance: High ventricular rates (>100) and loss of the atrial “kick” can decrease CO and precipitate heart failure, angina Risk for stroke due to risk of thrombus formation in the atria from the stasis of blood Treatment: Primary goal is to slow ventricular response by increasing AV block o Drugs to slow HR: Calcium channel blockers, beta-blockers o Electrical cardioversion o Antidysrhythmia drugs to convert atrial flutter to sinus rhythm or to maintain SR: amiodarone (Cordarone), propafenone (Rythmol), procainamide (Pronestyl), ibutilide (Corvert), flecainide (Tambocor), dronedarone (Multaq) o Radiofrequency catheter ablation can be curative therapy for atrial flutter Nursing implications: Assess for rapid heart rate and signs of decreased cardiac output --- angina, dyspnea, SOB, hypotension, fatigue, dizziness, palpitations Assess for signs of stroke Assist with cardioversion, radiofrequency catheter ablation Administer medications as ordered---antidysrhythmic and/or anticoagulant Monitor anticoagulant therapy---INR, PT 5 Atrial Fibrillation Identifying EKG characteristics: Rate: Atrial rate: 350 – 600 bpm o Ventricular rate: 50 - 180 bpm o Total disorganization of atrial electrical activity due to multiple ectopic foci resulting in loss of effective atrial contraction Rhythm: Grossly irregular P waves: No P wave. Instead chaotic, small “F” waves (fibrillatory waves). Wavy baseline. PR interval: Unable to measure. Nonexistent. QRS: Usually normal Etiology: Usually underlying heart disease---CAD, cardiomyopathy, HF, pericarditis, rheumatic heart disease, after cardiac surgery, hypertension Also, COPD, hyperthyroidism, alcohol intoxication, caffeine use, electrolyte disturbance Clinical significance: Can result in decreased cardiac output due to rapid rate and loss of atrial kick Atrial thrombi may form due to blood stasis (embolus is breaks away may cause a stroke) Treatment: Goals: o Decrease ventricular rate o Prevent embolic stroke Drugs for rate control: digoxin, beta-blockers, calcium channel blockers Drugs to maintain sinus rhythm: amiodarone, sotalol, ibutilide, dronedarone Long-term anticoagulation: Coumadin Cardioversion Radiofrequency catheter ablation Nursing implications: Assess for signs of decreased cardiac output Assess for signs of stroke Administer medications as ordered Assist with cardioversion, radiofrequency catheter ablation Monitor anticoagulant therapy (INR, PT) 6 Premature Ventricular Contractions (PVCs) Identifying EKG characteristics: Rate: Varies due to intrinsic rate and # of PVCs Rhythm: Irregular P waves: None associated with PVC; usually lost in the PVC or retrograde P wave PR interval: Not measurable with the PVC QRS: Wide and bizarre (> 0.12 sec), occurs prematurely T wave: Frequently in the opposite direction of the QRS complex Etiology: Stimulants: caffeine, alcohol, nicotine, aminophylline, epinephrine, isoproterneol Digoxin Electrolyte imbalances: Especially hypokalemia and hypomagnesemia Hypoxia, acidosis Fever Exercise, emotional distress Disease states: MI, mitral valve prolapse, HF, CAD Clinical significance: In normal heart, usually benign In heart disease, PVCs may decrease CO and precipitate angina and HF PVCs in CAD may lead to ventricular tachycardia (VT) or ventricular fibrillation (VF) Treatment: Treat the underlying cause o Oxygen therapy for hypoxia o Electrolyte replacement o Drugs: Beta-blockers, procainamide, amiodarone, lidocaine Nursing implications: Monitor for increased frequency, multiform, runs or R on T Assess for decreased cardiac output and administer medications as ordered. 7 Ventricular Tachycardia Identifying EKG characteristics: A run of 3 or more PVCs = V tach Rate: 150 – 250 beats per minute Rhythm: Usually regular P wave: None identified PR interval: Not measurable QRS: Wide, bizarre (> 0.12) Etiology: Reflects advanced myocardial irritability caused by: MI, CAD, electrolyte imbalances, cardiomyopathy, mitral valve prolapse, long QT syndrome, digitalis toxicity, CNS disorders Clinical significance: Recognize can be life threatening. May degenerate into ventricular fibrillation. VT can be stable (patient has a pulse) or unstable (patient is pulseless) Sustained VT: Severe decrease in CO---hypotension, pulmonary edema, decreased cerebral blood flow, cardiopulmonary arrest Treatment: Unstable pulseless: CPR, defibrillate, epinephrine, vasopressin, antiarrhythmics (IV amiodarone or lidocaine) Stable with a pulse: Antiarrhythmics (procainamide, sotalol, amiodarone or lidocaine), synchronized cardioversion Must treat if only V. tach only briefly and stops abruptly**** Nursing implications: Assess for underlying cause ACLS protocol, O2, code cart, intubation equipment at bedside Administer medications as ordered 8 Ventricular Fibrillation Identifying EKG characteristics: Rate: Ventricles are “quivering” ----no effective ventricular contraction; no rate Rhythm: Irregular and chaotic P waves: Not visible PR interval: Not measurable QRS: Not measurable Etiology: Acute MI, CAD, cardiomyopathy May occur during cardiac pacing or cardiac catheterization May occur with coronary reperfusion after fibrinolytic therapy Accidental electrical shock Hyperkalemia Hypoxia Acidosis Drug toxicity Clinical significance: Unresponsive, pulseless, and apneic state If not treated rapidly, death will result Treatment: Immediate initiation of CPR and ACLS measures with the use of defibrillation and definitive drug therapy Nursing implications: Assess patient, CPR, ACLS 9 Asystole Identify EKG characteristics: Rate: Absent Rhythm: Absent P waves: Absent or occasionally can be seen PR interval: Absent QRS: Absent Etiology: Advanced cardiac disease Severe cardiac conduction system disturbance End-stage HF Electrolyte imbalances, drug overdose, trauma Clinical significance: Unresponsive, pulseless, and apneic state Prognosis for asystole is extremely poor Treatment: CPR with initiation of ACLS measures (e.g. intubation, transcutaneous pacing, and IV therapy with epinephrine and atropine) Nursing implications: Identity patients at risk for asystole CPR, ACLS Family support 10 Practice Strips: V tach Rhythm: Regular Rate: 170 P wave: no p wave PR interval: no pr interval QRS interval: 0.24 QT interval: no QT ST segment and T wave: Rhythm interpretation: V tach 2. Rhythm: irregular Rate:70 P wave: P wave is present and irregular PR interval: 0.24 QRS interval: 0.04 QT interval: 0.48 ST segment and T wave: 0.24 Rhythm interpretation: Atrial fibrillation 3. 11 Rhythm: regular Rate: 100 P wave: yes PR interval:0.12 QRS interval: 0.04 QT interval: 0.28 ST segment and T wave Rhythm interpretation: second degree av block 4. Rhythm: irregular Rate:70 P wave: no PR interval: not measurable QRS interval: 0.04 QT interval:0.44 ST segment and T wave: \ Rhythm interpretation: junctional rhythm 12 5. Rhythm: irregular Rate: 80 P wave: yes PR interval: not measureable QRS interval: not measureable QT interval:0.24 ST segment and T wave: 0.12 Rhythm interpretation: Premature ventricular contraction 6. Rhythm: irregular Rate:70 P wave: No PR interval: unmeasurable QRS interval: 0.06 QT interval: 0.48 ST segment and T wave: ___________________ Rhythm interpretation: Third degree block 13 7. Rhythm: irregular Rate:90 P wave: yes PR interval: 0.12 QRS interval: 0.08 QT interval: 0.28 ST segment and T wave: 0.20 Rhythm interpretation: atrial flutter 8. Rhythm: Irregular Rate: P wave: 70 PR interval: 0.12 QRS interval:0.08 QT interval: 0.44 ST segment and T wave: ___________________ Rhythm interpretation: afib 14 9. Rhythm:irregular Rate:250 P wave: no PR interval: non measureble QRS interval:0.16 QT interval: non measurable ST segment and T wave: non measurable Rhythm interpretation: ventricular fibrillation 10. Rhythm:regular Rate: 20 P wave: _yes PR interval: 0.12 QRS interval: 0.08 QT interval: ST segment and T wave: 0.20 Rhythm interpretation: sinus bradycardia 15 11. Rhythm: irregular and chaotic Rate: not measureableP wave: not visible PR interval: Not measurable QRS interval: not measurable QT interval: not measurable ST segment and T wave: not measurable Rhythm interpretation: ventricular fibrillation 12. Rhythm:regular Rate:110 P wave: yes PR interval: 0.08 QRS interval: 0.06 QT interval: 0.24 ST segment and T wave: normal Rhythm interpretation: sinus tachycardia 16 13. Rhythm:irregular Rate:100 P wave: yes PR interval: 0.20 QRS interval: 0.12 QT interval: ST segment and T wave: ___________________ Rhythm interpretation: pvc 14. Rhythm: irregular Rate: 100 P wave: yes PR interval:0.12 QRS interval: 0.04 QT interval: 0.24 ST segment and T wave: 0.08 Rhythm interpretation: atrial fibrillation 17 The End!! 02/04/2011 BN