Dysrhythmias Flashcards
Sinus bradycardia
Causes
- WNL in well-conditioned heart (athletes)
- Increased ICP, increased vagal tone due to straining during defecation, vomiting, intubation, mechanical ventilation
Sinus bradycardia
Treatment
- ACLS protocol for atropine for S/S of low CO —> dizziness, weakness, altered LOC, low blood pressure
- Pacemaker
Sinus tachycardia
Treatment
Correction of underlying cause
B-blockers, CCBs for symptomatic patients
Sinus tachycardia
Causes
- Normal response to fever, exercise, anxiety, pain, dehydration
- May accompany shock, L-sided HF, cardiac tamponade, hyperthyroidism, anemia
- Atropine, Epi, quinidine, caffeine, nicotine, alcohol
Premature atrial contraction (PAC)
Description
- Premature, abnormal looking P waves
- QRS complexes after P waves except in very early or blocked PACs
- P wave often buried in the preceding T wave or identified in the preceding T wave
PAC
Causes
- May prelude SVT
- Stimulants, hyperthyroidism, COPD, infection and other heart diseases
PAC
Treatment
- Usually no TX required
- TX of underlying cause if pt symptomatic
- Carotid sinus massage
Atrial flutter
Description
- Atrial rhythm regular, rate 200-400 bpm
- Ventricular rate variable, depending on degree of AV block
- Saw-tooth shaped P wave!!
- PR interval not measurable
- QRS complexes uniform in shape but often irregular in rate
Atrial flutter
Causes
- HF, AV valve disease, PE, cor pulmonale, inferior wall MI, carditis
- Digoxin toxicity
Atrial flutter
Treatment
- If pt unstable w/ventricular rate > 150 bpm, prepare for immediate cardioversion
- If pt stable, drug therapy —> CCBs, b-blockers, antidysrhythmics
Atrial fibrillation
Description
- Atrial rhythm irregular, rate > 350-600 bpm
- Ventricular rhythm varies and is irregular
- PR interval indiscernible
- No P waves
Atrial fibrillation
Causes
-HF, COPD, thyrotoxicosis, constrictive pericarditis, MI, sepsis, PE, rheumatic heart disease, HTN, mitral stenosis, atrial irritation, complication of coronary bypass or valve replacement SX
Atrial fibrillation
Treatment
- If pt unstable w/ventricular rate > 150 bpm, immediate cardioversion
- If stable, drug therapy —> CCBs, B-blockers, digoxin, procainamide, quinidine, ibutilide, amiodarone, anticoagulants
- Dual chamber pacing, implantable atrial pacemaker, SX maze procedure
1st degree AV block
Description
-Normal except for prolonged PR interval (> 0.2 sec)
1st degree AV block
Causes
- Associated w/disease states or certain drugs, MI, CAD, rheumatic fever, hyperthyroidism, lyte imbalances (hypokalemia), vagal stimulation
- Drugs —> b-blockers, digoxin, CCBs, flecainide
1st degree AV block
Treatment
No treatment, monitor patient for new changes in rhythm
Premature ventricular contraction (PVC)
Description
- Atrial rhythm regular, ventricular rhythm irregular
- QRS premature, usually followed by pause; wide & distorted, usually > 0.14 sec
- Ominous when clustered, multifocal, or w/R waves on T pattern
PVC
Causes
- HF, old/acute myocardial ischemia/infarction/contusion
- Myocardial irritation by ventricular catheters (eg. pacemaker)
- Hypercapnia, hypokalemia, hypocalcemia
- Drug toxicity by cardiac glycosides, aminophylline, TCAs, b-adrenergic
- Caffeine, tobacco, alcohol use,
- Physiological stress, anxiety, pain
PVC
Treatment
- Procainaide, lidocaine, amiodarone IV
- Treat underlying cause
- D/C drug causing toxicity
- Potassium chloride IV if hypokalemia
- Magnesium sulfate IV if hypomagnesemia
Ventricular tachycardia
Monomorphic
QRS complexes are same shape, size, direction
Ventricular tachycardia
Polymorphic
QRS complexes gradually change back and fourth from one shape, size, and direction to another over a series of beats
Ventricular tachycardia
Causes
- Myocardial ischemia, infarction, or aneurysm
- CAD, rheumatic heart disease, mitral valve prolapse, HF, cardiomyopathy
- Ventricular catheters
- Hypokalemia, hypocalcemia
- PE
- Digoxin, procainamide, epinephrine, quinidine toxicity
- Anxiety
Ventricular tachycardia
Treatment
- If pulseless: CPR, follow ACLS protocol for defibrillation
- If pulse: if hemodynamically stable, follow ACLS protocol for admin of amiodarone —> if ineffective initiate synchronized cardioversion
What RX is given for polymorphic ventricular tachycardia (torsades de pointes)?
Magnesium sulfate IV
Ventricular fibrillation
Causes
- Myocardial ischemia/infarction, R-on-T phenomenon, untreated ventricular tach
- Hypokalemia, hyperkalemia, hypercalcemia, alkalosis, electric shock, hypothermia
- Digoxin, epi, or quinidine toxicity
Ventricular fibrillation
Treatment
- If pulseless: start CPR, follow ACLS protocol for defibrillation
- ET intubation
- Admin of epi or vasopressin, lidocaine, amiodarone —> if ineffective mag sulfate
Asystole
Causes
- MI, aortic valve disease, HF, hypoxemia, hypo/erkalemia, severe acidosis, electric shock, ventricular arrhythmia, AV block, PE, heart rupture, cardiac tamponade, electromechanical dissociation
- Cocaine overdose
Normal PR interval
0.12 - 0.2 seconds (3-5 small boxes)
Normal QRS
0.06 - 0.12 sec
Abnormal ST findings
- > 1 mm segment elevation or depression from isoelectric line
- T wave = opposite direction than R wave
Hs and Ts for determining cause of asystole
Hs: hypovolemia, hypoxia, H+, hyper/hypokalemia, hyper/hypoglycemia, hypothermia
Ts: toxins, tamponade, thrombosis, tension pneumothorax, trauma
Complications of pacemaker
Infection Bleeding, hematoma formation Dislocation of lead Skeletal muscle or phrenic nerve stimulation Cardiac tamponade Pacemaker malfunction
