EKG Rhythms and Clinical Implications

Junctional escape rhythm

Occurs in AV tissue when SA node fails (only passes impulse to bundle of his). Regular rhythm, 40-60 bpm. P-waves usually not there or inverted. Causes: digitalis toxicity, hypoxia, acute infections, etc. NEVER TERMINATED NATURALLY.

Premature junctional beats

Aka escape beat. Inverted P-wave prior or after QRS. Causes: Usually CAD.

Junctional tachycardia

3+ junctional escape beats in a row. HR: 120-200 bpm. P-waves before or after QRS.

Premature ventricular contractions (PVC)

Occurs below bundle of His. No failure of normal rhythm. Wide, bizarre QRS (b/c took longer for ventricles to depolarize) - no P-wave. Antiarrhythmic therapy needed if: Occur with ↑ frequency, occur in a pattern, fall close to a t-wave, R on T phenomenon. Uni or multifocal. 2 occurring together: couplet. Every other beat: bigeminy; every 3 beats: trigeminy; 3+ PVC's: v-tach.

Fusion beats

Sinus and ectopic impulses occur at the same time. P-wave with wide, bizarre QRS (less wide than PVC). p-p interval constant. p-r interval abnormally short if visible.

Ventricular tachycardia (V-tach)

Life threatening. 140-200 bpm. No p-waves. Wide and bizarre QRS. R-R is regular. Usually initiated by single PVC. Might see a capture beat (normal sinus beat sneaks through). 3 or more PVCs in a row = V-tach.

Ventricular flutter

TRANSITION RHYTHM from v-tach to v-fib. 200+ bpm. Usually unconscious. Shockable.

Ventricular fibrillation (V-fib)

Chaotic, no PQRST noticeable. Ventricles are quivering. Fatal. Shockable. Epinephrine may be used to convert fine v-fib to coarse v-fib for better response from defibrillator.

Pulseless electrical activity

When a person has some electrical impulses but no pulse.

Ventricular escape beats

When sinus node can't maintain a rhythm. Life saving mechanism. SA node 60-100 bpm. AV node 40-60 bpm. Purkinje fibers 20-40 bpm. QRS widened. Looks like it goes backward.

Hypokalemia

Potassium levels below 3.6 mEq/L. Depressed ST segment. Prominent U wave. Prolonged QT/QU interval. May be associated with: starvation, vomiting, diarrhea, diuretic therapy, steroid use, etc. May also cause: PVC's. Mainly affects repolarization, so look for changes near T-wave.

Hyperkalemia

Potassium levels greater than 5.2 mEq/L. Usually has tall, peaked, narrow T-waves that are symmetrical. Diminished height of R wave. Small P waves. Widened QRS. Mainly associated with: burns (2nd/3rd degree), crushing injuries, excessive amounts of K+ solutions, kidney damage, etc. Depresses normal electrical activity of the myocardial cells. May also cause: sinus bradycardia, sinus arrhythmia, first degree AV block, V-tach, V-fib, asystole.

Hypocalcemia

Calcium levels below 9 mg%. Changes noted in ST segment (lengthening). No change in QRS or T-wave. Usually an upset in the acid-base balance due to hyperthyroidism.

Hypercalcemia

Calcium levels more than 11 mg%. Causes increased contractility of the heart. Has a shortened ST segment (may even be absent). Watch for acidosis.

Hypomagnesemia

May occur in tandem with hypokalemia (low K+). May result from: diarrhea, hypoparathyroid disease, pancreatitis, ulcerative colitis, SEVERE alcoholism.

Hypermagnesemia

May result from: renal failure, dehydration, diabetic acidosis, oliguria (diminished urine output).

Junctional escape rhythm

Premature junctional beats

Junctional tachycardia

Unifocal PVC

Multifocal PVC

v-tach

v-flutter

v-fib

ventricular escape beat

hypocalcemia