Cardiac Rhythms and DysrhythmiasRhythm and Strip ECG Characteristics Management

Normal sinus rhythm Rate: 60 – 100 bpmRhythm: regularThere is one P for every QRSPR interval: 0.12 – 0.20 secondsQRS complex: 0.06 – 0.10 seconds

This is a normal heart rhythm so no treatment is required

Sinus tachycardia Rate: 101 – 150 bpmRhythm: regularThere is one P for every QRS but may be hidden with T wave due to speedPR interval: 0.12 – 0.20 secondsQRS complex: 0.06 – 0.10 seconds

This is only treated if client is symptomatic or is at risk for myocardial damageIf there is an underlying cause, beta-blockers or verapamil can be used

Sinus bradycardia Rate: < 60 bpmRhythm: regularThere is one P for every QRSPR interval: 0.12 – 0.20 secondsQRS complex: 0.06 – 0.10 seconds

This is only treated if client is symptomatic; administer IV atropine, isoproterenol, and/or pacemaker may be used

Premature atrial contractions (PAC) Rate: variesRhythm: regular with early beats originating in atriaThere is one P for every QRSPR interval: not measuredQRS complex: 0.06 – 0.10 seconds

This usually requires no treatment. Advise client to reduce alcohol intake, reduce stress, and stop smoking

Atrial flutter Rate: atrial 240 – 360 bpm, ventricular rate depends on degree of AV blockRhythm: regularP:QRS ratio: 2:1. 4:1, 6:1, or variablePR interval: not measuredQRS complex: 0.06 – 0.10 seconds

This is treated with synchronized cardioversion; meds to reduce ventricular response such as beta-blocker or calcium channel blocker followed by a class I antidysrhythmic or amiodarone

Atrial fibrillation Rate: 300 – 600 bpm; ventricular 100 – 180 bpm in untreated clientsRhythm: irregularly regularP:QRS ratio is variablePR interval: not measuredQRS complex: 0.06 – 0.10 seconds

This is treated with synchronized cardioversion; meds to reduce ventricular response rate such as metoprolol, diltiazem, or digoxin; anticoagulant therapy to reduce risk of clot formation and stroke

Premature ventricular contractions (PVC) Rate: variableRhythm: irregular; PVC interrupts underlying rhythm and followed by a compensatory pauseNo P wave noted before a PVCPR interval: absentQRS complex: wide, > 0.12 seconds

This is treated if client is symptomatic; advise against using stimulants (caffeine, nicotine); drug therapy includes, class I and III antidysrhythmics and possibly addition of a beta blocker

Ventricular tachycardia Rate: 100 – 250 bpmRhythm: regularNo indentifiable P wavePR interval: not measuredQRS complex: ≥ 0.12 seconds; bizarre shape

This is treated if VT is sustained or if client is symptomatic; treatment includes IV procainamide, lidocaine.If unstable, a class III antidysrhythmic and immediate cardioversion; ablation surgery or internal defibrillator for repeated episodes

Ventricular fibrillation Rate: too rapid to countRhythm: grossly irregularNo identifiable P wavesPR interval: noneQRS complex: bizzare, varying in shape and direction

Immediate defibrillation

First-degree AV block Rate: 60 – 10 bpmRhythm: regularThere in one P for every QRSPR interval: > 0.20 secondsQRS complex: 0.06 – 0.10 seconds

No treatment required

Second-degree AV block type 1 (Mobitz 1, Wenckebach) Rate: 60 – 100 bpmRhythm: atrial regular, ventricular irregularP:QRS ratio: 1:1 until P wave is blocked w/ no QRS followingPR interval: progressively lengthens in regular patternQRS complex: 0.06 – 0.10 seconds; sudden absence of QRS complex

Treatment includes monitoring and observation; atropine and isoproterenol if client is symptomatic (rarely progresses to a higher level of block)

Second-degree AV block type 2 (Mobitz 2) Rate: atrial 60 -100 bpm, ventricular < 60 bpmRhythm: atrial regular, ventricular irregularP:QRS ration: typically 2:1, may varyPR interval: constant PR interval for each conducted QRSQRS complex: 0.06 – 0.10 seconds

Treatment includes atropine or isoproterenol; pacemaker therapy

Third-degree block (complete heart block) Rate: atrial 60 – 100 bpm; ventricular 15 – 60 bpmRhythm: both atrial and ventricular are regularIndependent rhythm (no relationship between P and QRS)PR interval: not measuredQRS complex:

Immediate pacemaker therapy