ECG Simplified – Part 8

ECG Simplified – Part 8

Next comes ventricular arrhythmias. Ventricular ectopic beats are also known as ventricular premature beats or complexes (VPB or VPC, sometimes PVC – premature ventricular complexes). Ventricular premature beats are easily recognized on the ECG by their wide bizarre QRS complexes, not preceded by a P wave. Secondary ST depression and T wave inversion when the QRS is dominantly positive are also seen. Ventricular ectopic beats are followed by a compensatory pause before the next sinus beat. Coupling interval is the interval between the VPC and the preceding sinus beat.
Initial two VPCs in this ECG are isolated while the last two occur in rapid sequence as a couplet. VPC couplets may be a forerunner of ventricular tachycardia. Isolated VPCs and the couplet are followed by a compensatory pause. All the VPCs have same shape or morphology (monomorphic) indicating the same focus of origin (unifocal). Unifocal VPCs usually have the same coupling interval.
ECG showing ventricular ectopic bigeminy, with grouped beating of two beats followed by a pause. Each narrow QRS sinus beat is followed by a wide QRS ventricular ectopic beat. Narrow QRS sinus beat has a preceding P wave, while the wide QRS ventricular ectopic beat does not have a preceding P wave.
Monitor screenshot showing ventricular premature complexes occurring in a trigeminal sequence, another form of grouped beating. Two sinus beats followed by a ventricular ectopic beat – ventricular trigeminy or VPC trigeminy.
ECG showing VPC salvo. The original meaning of the word salvo is a series of shots fired in rapid sequence from a gun or simultaneously from multiple guns. Here it is a salvo of three consecutive ventricular ectopic beats. It can also be considered as a short run of non-sustained ventricular tachycardia. Isolated VPC is seen subsequently.
This ECG shows multiple short runs of ventricular tachycardia. Ventricular tachycardia is a fast rhythm originating from the lower chambers of the heart. If it lasts less than 30 seconds, it is called non-sustained ventricular tachycardia (NSVT). Ventricular tachycardia is a much more dangerous arrhythmia than supraventricular tachycardia.
Here it is a sustained ventricular tachycardia, which typically lasts more than 30 seconds. Sustained ventricular tachycardia is a medical emergency. If it is not responding to medications, a controlled direct current shock is given using a defibrillator to abolish this rhythm. After that, usually sinus rhythm is restored spontaneously. This is a monomorphic ventricular tachycardia, meaning that all beats have the same shape in a given ECG lead.
This is another arrhythmia originating from the ventricles, known as accelerated idioventricular rhythm. Rate is slower than 100 beats per minute and does not qualify for the designation of tachycardia. AIVR is a classical arrhythmia seen after a blocked blood vessel to the heart muscle is opened up either by clot dissolving medication or by mechanical removal in angioplasty. AIVR usually needs no specific medical treatment as it subsides soon. QRS is wide as in other rhythms originating from the ventricles.
Ventricular fibrillation or VF is a life-threatening arrhythmia, which leads to death unless promptly corrected by electrical defibrillation (direct current or DC shock). In VF, the electrical activity is so disorganized that no ventricular contraction is possible, and ventricle remains still in a state of cardiac arrest. Ventricular fibrillation is recognized on the ECG as a highly disorganized electrical activity. Each wave has a different shape. When multiple simultaneous leads are available as in this case, the shape is different between the leads as well. If defibrillation is not immediately available, chest compressions and artificial breaths have to be started immediately, that is cardiopulmonary resuscitation or CPR.