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An idioventricular rhythm is a cardiac rhythm characterized by a rate of <50 beats per minute (bpm), absence of conducted P waves and widening of the QRS complex. [1] In cases where the heart rate is between 50 and 110 bpm, it is known as accelerated idioventricular rhythm and ventricular tachycardia if the rate exceeds 120 bpm.
The most obvious abnormal finding will be abnormal P waves. One of three options can occur: [12] 1. There are no P waves. This is because of either failure of retrograde flow to the atria or the P wave is hidden in the QRS. If the P wave is hidden that implies the atria depolarize at the same time as the ventricles. 2.
On an ECG, the QRS complex will be abnormally shaped when looking at ventricular ectopic activity, often it occurs earlier with an absent P wave. It can be perceived as a skipped beat on both the ECG and through normal pulse-taking. [12] During atrial ectopic activity where the P wave is normally rounded can be inverted or peaked.
Percussive pacing, also known as transthoracic mechanical pacing, is the use of the closed fist, usually on the left lower edge of the sternum over the right ventricle in the vena cava, striking from a distance of 20 – 30 cm to induce a ventricular beat (the British Journal of Anaesthesia suggests this must be done to raise the ventricular pressure to 10–15 mmHg to induce electrical activity).
Atrial escape (rate 60–80): originates within atria, not sinus node (normal P morphology is lost). Junctional escape (rate 40–60): originates near the AV node; a normal P wave is not seen, may occasionally see a retrograde P wave. Ventricular escape (rate 20–40): originates in ventricular conduction system; no P wave, wide, abnormal QRS.
The electrocardiogram (ECG) generally shows irregular QRS complexes without P-waves. [98] By contrast, the ECG for ventricular tachycardia will generally show a wide complex QRS with more than 100 beats occurring per minute. [ 99 ]
A criterion for sinus rhythm is that P waves and QRS complexes appear 1-to-1, thus implying that the P wave causes the QRS complex. [50] Once sinus rhythm is established, or not, the second question is the rate. For a sinus rhythm, this is either the rate of P waves or QRS complexes since they are 1-to-1.
Bradycardia, also called bradyarrhythmia, is a resting heart rate under 60 beats per minute (BPM). [1] While bradycardia can result from various pathologic processes, it is commonly a physiologic response to cardiovascular conditioning or due to asymptomatic type 1 atrioventricular block.