Final answer:
Idioventricular rhythm (IVR) and accelerated idioventricular rhythm (AIVR) differ in their ventricular contraction rates, with IVR being slower than AIVR and both requiring ECG for diagnosis.
Step-by-step explanation:
The difference between an idioventricular rhythm (IVR) and an accelerated idioventricular rhythm (AIVR) lies primarily in their rate of ventricular contraction. IVR occurs when the heart's ventricles contract at a slow rate, typically below 50 beats per minute, and originates from the ventricles due to the absence of supraventricular impulses. In contrast, AIVR is a slightly faster but still abnormal rhythm, with ventricular contractions typically between 50-100 beats per minute. It can be thought of as an intermediate rhythm between normal sinus rhythm and IVR, sometimes occurring during reperfusion after a myocardial infarction (heart attack). Both rhythms can be identified through an electrocardiogram (ECG) and must be evaluated in the clinical context, as the underlying conditions can be different.