Reperfusion Arrhythmias

Scenario: A 64-year-old male is in the holding room of the adult cardiac catheterization laboratory following primary percutaneous coronary intervention (PCI) for treatment of acute ST elevation myocardial infarction (MI). The procedure went well; however, while he was awaiting transfer to the coronary care unit, this rhythm occurs. The patient’s blood pressure is stable (110/70), he has no complaints of chest pain, and he is alert and oriented.For every ECG, we recommend you systematically examine the following 8 features (check all that apply):Interpretation: Ventricular tachycardia versus accelerated idioventricular rhythm (AIVR).Ventricular tachycardia (VT) is an arrhythmia originating from an ectopic focus within the ventricular myocardium. In the above example, the rhythm is monomorphic because it is regular and originating from a single focus resulting in identical QRS complexes. No absolute ECG criteria exist for establishing the presence of VT. However, several ECG features suggest VT, including the following:In this example, it is difficult to identify P waves because of the rapid ventricular rate. Hence, the presence or absence of AV dissociation cannot be determined. In addition, evaluation of ischemia is difficult because during VT the defection of the ST segment is deviated opposite the QRS complex. Hence, the ST-segment depression observed in V1 is expected and therefore is not considered ischemia. However, the ventricular rate, QRS width, and morphological criteria in V1 suggest that this rhythm is VT.One type of VT is AIVR, which is sometimes termed slow VT since the ventricular rate is between 60–110 beats per minute. The onset of AIVR is typically nonparoxysmal (gradual) and results when the ventricular rate exceeds the sinus rate because of a slowing sinus rate, or sinoatrial (SA) or AV block. AIVR may occur following successful treatment of acute MI (primary PCI, or thrombolytics) once reperfusion is restored in the infarct-related artery. Although the ventricular rate in this example exceeds the criteria for AIVR, given that the patient had just been treated with PCI for acute ST elevation MI, AIVR is most likely.Management is determined by a patient’s response to the arrhythmia. Specifically, is the patient hemodynamically stable? Therapy for AIVR is often unnecessary because the heart rate is slower than that of sustained VT with rapid ventricular response. Symptomatic patients should be treated promptly following current Advanced Cardiac Life Support guidelines in order to restore perfusion and avoid the development of ventricular fibrillation. This patient should be monitored closely for further arrhythmias and hemodynamic compromise.