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RELIAS DYSRHYTHMIA BASIC TEST
COMPREHENSIVE REVIEW 2026
โ Sinus Bradycardia. Answer: <60bpm Present in healthy and diseased hearts Associated with sleep, pain, MI, acute spinal cord injury, drugs (digitalis, beta-blockers, verapamil, dilitiazem) In hearts that can't compensate it will lead to low cardiac output. Tx: none unless symptomatic. Tx can include: atropine or cardiac pacing. โ Sinus tachycardia. Answer: >100bpm Stress, exercise, stimulants (caffeine & nicotine), fever, anemia, hyperthyroidism, hypoxemia, HF, shock, drugs-atropine, epinephrine, dopamine. Causes inc in O2 demand on myocardium and dec filling time of the ventricles Tx: treat underlying cause ie. Sedation, O2 admin, digitalis, diuretics, beta-blockers โ Sinus dysrhythmias. Answer: Shortest RR interval to longest RR interval varies by >0.12 secs. Rate can inc with inspiration and dec with expiration
Normal, especially in young ppl so not necessarily diseased heart Tx: none, usually asymptomatic โ Premature Atrial Contraction (PAC). Answer: Can occur at any rate The rhythm is irregular because of the early beat but is regular at other times There is a P for every QRS and a QRS for every P The P waves all look the same except the P in front of the PAC will be differentโP wave is buried in the preceding T wave Causes: emotions, tobacco, alcohol, caffeine, rheumatic heart disease, ischemic heart disease, mitral stenosis, HF, hypokalemia, hypomagnesemia, medications, hyperthyroidism, atrial irritability. Symptoms: Usually asymptomatic, May feel pause or skipped beat, May lead to atrial fibrillation or other atrial rhythms Treatment: none โ Supraventricular Tachycardia. Answer: A general term used to describe any narrow tachycardia Includes: PSVT Atrial tachycardia Multifocal atrial tachycardia Atrial flutter with 2:1 conduction
โ Atrial Tachycardia. Answer: Type of PSVT but is an uncommon cause of PSVT Pacemaker shifts from the SA node to a focus within the atrium that fires at a rate of >100 bpm May be sustained or paroxysmal โ Atrial Flutter. Answer: Rate: atrial 250-350/min, ventricular rate varies depending on amount blocked by AV node Rhythm: atrial rhythm is regular, ventricular rhythm may be regular or irregular P waves: absent, No PR interval, QRS: usually normal "saw-toothed" flutter waves (F waves), flutter waves: QRS complex conduction can be 2:1, 3:1, 4:1. Cause: Underlying cardiac disease (CAD, rheumatic heart disease, HF, MI, post open heart) Results in hemodynamic compromise d/t dec filling of ventricles and loss of atrial kick which dec CO. Thrombi can develop and result in pulmonary emboli, cerebral emboli, or MI. Treatment: Unstable: synchronized cardioversion Stable: control rate If ventricular rate is > 120/min no LV dyfxn: beta blocker, calcium channel blockers or digoxin
If ventricular rate is >120 with LV dysfxn: amiodarone, cardiazem, digoxin โ Atrial Fibrillation. Answer: Erratic impulse formation in atria No discernible P wave Irregular ventricular rate Aberrant (abnormal) ventricular conduction can occur Results in loss of atrial kick High risk for pulmonary or systemic emboliCharacteristics: Rate: atrial rate is too fast to count (350-500bpm). Ventricular rate is variable. A "controlled ventricular response" means < 100/min Rhythm: irregularly irregular P waves: absent instead see fibrillatory waves PR: none QRS: usually normal though may be wide due to aberrancyTreatment: Same as atrial flutter Approximately 50% of all patient with new onset A Fib will convert to SR spontaneously within 24-48 hrs The longer the rhythm is present, the less likely conversion to NSR is likely Chronic, permanent: digoxin, amiodarone, or a beta blocker for rate control and coumadin for prevention of thrombus formation
Attempt to identify cause If symptomatic give atropine 0.5 mg IV or initiate transcutaneous pacing Withhold medications that may worsen the problem Assess for digoxin toxicity โ Premature Junctional Contractions (PJC). Answer: Early beats initiated by AV junction from a single ectopic focus P-wave changes PR interval is shorter than normal, narrow QRS Usually a noncompensatory pause May occur in healthy people or those with underlying heart disease (ischemia, MI), stimulants (nicotine, caffiene) or drugs (digitalis). May feel "skipped" beat Treatment: not necessary โ Premature ventricular Contractions (PVC). Answer: Wide and bizarre beats Compensatory pause Patterns Bigeminy (PVC after one sinus beat)and trigeminy (PVC after two consecutive sinus beats) Couplets (2 PVCs in a row) and triplets (3 PVCs in a row)
Unifocal (from one spot) versus multifocal (from 2 or more spots so look different)Characteristics: Rate: PVCs can occur at slow, normal or fast rates Rhythm: irregular, due to early beat P waves: usually hidden within the QRS and is not visible PR: none QRS: always widened (0.12 sec or >) and distorted in shape โ PVCs. Answer: Frequent: 6 or more/min Unifocal: PVCs from one focus Multifocal: PVCs have different shapes, may be > 1 ectopic area in the ventricles Bigeminy: every other beat is a PVC Trigeminy: every 3rd beat is a PVC Couplets: two consecutive PVC Cause: occur w/ or w/o heart disease. Myocardial ischemia/infarction, hypokalemia, increased catecholamines, mechanical irritation with a wire or catheter Treatment: isolated PVCs-no treatment. Multiple PVCs- antiarrhythmic agents (amiodarone, lidocaine). Potassium replacement if low.
QRS: widened (> 0.12 sec), bizarre โ Monomorphic Ventricular Tachycardia cont.. Answer: Significance: Assess for symptoms of low cardiac output Assess for ischemia, infarction, hypokalemia, hypoxemia, acidosis, drugs that stimulate the sympathetic nervous system Treatment: If stable: consider Adenosine only if regular and monomorphic, or lidocaine. If unstable: Call a Code, CPR until a defibrillator arrives Immediate defibrillation with 100J Antiarrhythmics: procanimide, amiodarone, sotalol If progresses to VF, resume CPR Follow ACLS guidelines โ Torsades de Pointes. Answer: A long QT interval (100-300bpm), unstable rhythm Cx: hypokalemia, hypocalcemia, hypomagnesemia, cardiac disease w/prolonged QT
May terminates spontaneously or require cardioversion or defibrillation, drugs or pacing. โ Polymorphic VT, normal QT. Answer: May require defibrillation, drugs or pacing โ Ventricular Fibrillation. Answer: Chaotic pattern, rapid, irregular No discernible P, Q, R, S, or T waves Coarse vs. fine Cause: MI or ischemia, electrocution, prolonged QT interval, circulatory failure No pulse and no cardiac output--life threatening Emergent defibrillation Most common cause of cardiac arrest โ V-Fib cont.. Answer: Characteristics: Rate: unable to determine Rhythm: irregular P waves: none PR: none QRS: rapid, chaotic, uncoordinated electrical activitySignificance: Lethal arrhythmia, a Code Blue situation
โ Ventricular Standstill (Asystole). Answer: Asystole No P, Q, R, S, or T waveforms Assess in two leads Why? No cardiac output, begin CPR Death โ First-Degree Block. Answer: Delayed conduction from sinus node to AV node Rate: normal, slow or fast depending on the underlying rhythm Rhythm: regular P wave precedes QRS, 1: Prolonged PR interval but constant >0.20 second Same PR interval for each beat Frank the bus driver: consistently late; Frank the bus driver (p wave) picks up his passengers (QRS) regularly late to arrive at the bus stop every day. The time he's late is the PR interval. Although Frank keeps his passengers waiting, he's always consistent. Cause: Found in healthy and diseased hearts of all ages Drugs (digitalis, BB, CCB), CAD, infectious disease, congenital lesions Treatment: None but monitor b/c can progress to second- or third-degree
โ Second-degree AV block Type I (Wenckebach). Answer: Block at level of AV node Atrial rhythm regular Ventricular rhythm irregular P wave: one per QRS until missed QRS, more P's than QRS complexes PR interval: Progressive prolongation until a QRS complex dropped. Wendy the bus driver Always arrives later and later, so ppl leave the bus stop โ Second-degree Wenckebach cont.. Answer: Steadily lengthening PR interval Nonconducted P waves P-P interval regular R-R interval irregular QRS normal until dropped Self-limiting; rarely progresses May decrease cardiac output Usually associated with a block at the bundle of His, caused by drugs/disease that affect the AV node (digitalis, myocarditis, inf MI) Wendy, a bus driver (p wave) is late and forgetful. She arrives late to pick up passengers (QRS) at one stop and even later at subsequent stops (PR interval). She is so late on her last stop that the passengers
Occasional P wave not followed by QRSMoe the bus driver is never late (constant PR interval) but he makes more stops than is needed. He arrives on time to pick up passengers (QRS complex) but then makes stops where there are no passengers to board (p wave w/o a QRS). Block is at the level below the AV node (infranodal) More dangerous than Type I because electrical activation of the ventricles may depend on less reliable conduction pathways More P waves than QRS complexes, but when the P waves do conduct they conduct at the same interval โ Second-Degree Mobitz Type II pt.2. Answer: Characteristics: Rate: Atrial: constant, usually 60-100/min Ventricular: slower due to blocked beats Rhythm: Atrial: regular, P waves march out Ventricular: regular or irregular P waves: normal, some P waves not followed by QRS complexes PR: constant interval for conducted beats QRS: normal or can be wide > 0.12 sec Conduction: ratio can vary from 4:1, 3:1 or 2:1. Causes: age related degeneration changes, new MI (ant wall), post cardiac surgery Treatment: Assess patient for symptoms:
Asymptomatic: notify MD, observation and monitor, hold drugs that slow AV conduction (BB, CCB, digoxin) prepare for transvenous pacing. Symptomatic (bradycardia): initiate transcutaneous pacing (TCP) or Dopamine if pt is hypotensive โ Third Degree Block (Complete). Answer: Atria and ventricles beat independently of each other P waves not associated with QRS complex PR interval varies but no pattern like Wenckebach P-P intervals regular R-R intervals regular Junctional (narrow QRS) or ventricular (wide QRS) escape rhythms pace Cause: same as other blocks May need pacemaker Temporary until permanent implanted Hemodynamic status based on ventricular rate Thor the bus driver: does not have a consistent schedule and so misses his passengers so they find their own ride Thor the bus driver (p wave) tries very hard but always misses his passengers b/c he doesn't have a consistent schedule (PR interval) so he misses his passengers (QRS complex) find their own ride.
If symptomatic: Notify MD, administer atropine for bradycardia and prepare for transcutaneous pacing (TCP). *atropine only effective if QRS is narrow indicating an AV node block, has little/no effect on wide QRS (bundle branch level) blocks. Administer dopamine infusion 5-20 mcg/kg/min if hypotensive. โ Atrial Paced Beat. Answer: โ Ventricular Paced Beat. Answer: โ Dual Chamber. Answer: โ
