Happy Fourth of July

Identify the following rhythms.

1.

a. Sinus rhythm with PACs

b. Sinus rhythm with PJCs

c. Sinus arrhythmia

d. Sinus rhythm with PVCs

2.

a. Atrial flutter

b. Atrial fibrillation

c. Sinus arrhythmia with PVCs

d. Sinus rhythm with dropped PACs

3.

a. Normal sinus rhythm

b. First degree block

c. Junctional rhythm

d. Sinus arrest

4.

a. Atrial fibrillation

b. Multifocal atrial tachycardia

c. Ventricular tachycardia

d. Ventricular fibrillation

5.

a. Accelerated junctional rhythm

b. Atrial fibrillation

c. Accelerated idioventricular rhythm

d. Normal sinus rhythm

6.

a. Complete heart block

b. Agonal rhythm

c. P wave asystole

d. Asystole

7.

a. Idioventricular rhythm

b. Complete heart block

c. Ventricular standstill

d. Agonal rhythm

8.

a. Sinus bradycardia

b. Idioventricular rhythm

c. 2nd degree heart block type II

d. Junctional rhythm

9.

a. Ventricular tachycardia

b. Accelerated idioventricular rhythm

c. Supraventricular tachycardia

d. Junctional tachycardia

10.

a. Sinus rhythm with multifocal PVCs

b. Sinus rhythm with unifocal PVCs

c. Sinus rhythm with pauses

d. Sinus rhythm with ventricular bigeminy

Answers

1. The answer is: b. Sinus rhythm with PJCs.  The rhythm is irregular.  The heart rate is 60 bpm.  Upright P waves are seen in lead II and they are associated with a QRS complex.  The QRS complexes are narrow. The T waves are inverted. Two early beats are seen, complexes 2 and 4.  No P waves are seen before these complexes and the ectopic QRS complexes are narrow.  So, this fits the description of PJCs.  PR: .12 sec, QRS: .08 sec, QT: .40 sec.

2. The answer is: a. Atrial flutter.  The rhythm is a little irregular.  The rate is about 70 bpm.  There are flutter waves present with variable conduction, 3:1 and 4:1.  The QRS complexes are wide.  No ectopic beats are seen.  PR: ---, QRS: .12 sec, QT: .44 sec.

3. The answer is: b. First degree block.  The rhythm is irregular, so there is sinus arrhythmia present.  The heart rate is 50 bpm.  There are uniform P waves seen with each QRS complex.  The PR interval is prolonged.  The QRS complexes are narrow, so the conduction through the ventricles is normal.  PR: .32 sec, QRS: .08 sec, QT: .40 sec.

4. The answer is: d. Ventricular fibrillation.  The rhythm is irregular.  The rate is upwards around 300 bpm.  No P waves are identified.  The QRS complexes are not very organized.   This is a pulseless rhythm so let’s start some CPR while somebody grabs the crash cart because we are going to need to shock this rhythm.

5. The answer is: a. Accelerated junctional rhythm.   The rhythm looks very regular.  The heart rate is 75 bpm.  The P waves are inverted and are paired with a QRS complex.  The QRS complexes are narrow.  No ectopic beats are seen.  PR: .16 sec, QRS: .08 sec, QT: .36 sec. Because the heart rate is between 60 and 100 we call this an accelerated junctional rhythm.  If the rate were between 40 – 60 bpm then we would just call it a junctional rhythm.

6. The answer is: b. Agonal rhythm.  The rhythm is irregular.  The rate is around 20 bpm. No P waves are seen.  The absence of P waves points toward a ventricular rhythm.   The QRS complexes are wide.  PR: ---, QRS: .12 sec, QT: .48 sec.   This would be an example of a PEA rhythm.  There would not be a detectable pulse with this rhythm.  The vasoconstrictors epinephrine and vasopressin would be indicated.  Look for any reversible causes: hypoxia, hyper/hypokalemia, acidosis, tension pneumothorax, cardiac tamponade, cardiac ischemia, pulmonary embolus.

7. The answer is b. Complete heart block.   The rhythm looks regular.  The ventricular rate is around 34 bpm.  The atrial rate is about 100 bpm.   The P waves are uniform and upright in lead II but they are not paired with a QRS complex.  The atrium and the ventricles are working together.  The impulses from the atria are not reaching the ventricles due to some block the conduction system.  The ventricles are beating on their own.  Recall that the inherent rate of ventricles is 20 – 40 bpm

8. The answer is: d. Junctional rhythm. The rhythm is regular.  The rate is 50 bpm.  The P waves are negative in lead II so this points toward some retrograde conduction.  The QRS complexes are narrow. No ectopic beats are seen.  PR: .12 sec, QRS: .08 sec.  QT: .32 sec.  Recall that with a junctional rhythm the P waves may be inverted before the QRS complex, absent, or inverted after the QRS complex.

9. The answer is: a. Ventricular tachycardia.   In this case we have a polymorphic ventricular tachycardia.  It is not torsades de pointes (TdP) because all the QRS complexes have the same polarity.  Remember that with TdP the QRS complexes appear to flip from positive to negative in a cyclic fashion.  If the patient is pulseless we can shock this rhythm at 200 joules initially.  Vasopressin and epinephrine are your first vasoconstrictors.  Amiodarone would be your first antiarrhythmic.  Consider magnesium too.

10. The answer is: d. Sinus rhythm with ventricular bigeminy.  The rhythm looks regular.  The rate is 80 bpm.  The P waves are upright, uniform, and married to a QRS complex.  The sinus QRS complexes are narrow- so our conduction system through the ventricles is intact.  We have uniform PVCs seen every other beat- bigeminy.  PR: .16 sec, QRS: .08 sec, QT: .40 sec.