IschemiaInsufficient supply of oxygen to meet the oxygen demands of tissue. Anaerobic metabolism becomes increasingly important during periods of ischemia. Ischemia results from an inadequate blood flow that fails to meet the oxygen demands (energy demands) of tissues. If tissues... and sympathetic stimulation can enhance a ventricle’s automaticityA cardiac cell’s (usually pacemaker cells such as the SA node, AV node or His-Purkinje network) ability to self-initiate an impulse; note that abundant catecholamines and/or ischemia enhances automaticity – non-pacemaker cells may become pacemaker cells. The SA node, usually..., stimulating the ventricle to initiate an impulse before a sinus initiated wave reaches the ventriclesThe larger chambers of the heart (3 times the volume and muscle thickness than the atria), responsible for the pumping of blood to the lungs and the rest of the body.. This solitary wave doesn’t ride the AutobahnAn electrical wave envelops the ventricles very quickly IF the Bundle Branches and the Purkinje Network are utilized. This is comparable to getting off the back country roads and racing down the freeway. The rapidly conducting bundle branches could be.... Rather, this one wave must traverse both ventricles. The efficient autobahn is not utilized; instead, slower routes cross the ventricular myocardiumThe muscle layer of the heart; the middle layer that is responsible for contraction of the heart. The muscular myocardium is the thickest layer and the workhorse of the heart. It is composed of specialized muscle and electrical cells that.... As a result, the distance and time taken to depolarize the ventricles are longer. A wide QRS of 3mm or more is produced.
Rhythms that are initiated in the ventricles have wide QRS complexes. A second characteristic of these ventricular rhythms is that the T waveThe wave that arrives after the QRS; is a graphical presentation of ventricular repolarization. Expect a T wave to follow every QRS complex. The T wave is a graphic representation of the repolarization of the ventricle. The T wave is... is usually (though not always) facing the opposite polarity as the R waveFollowing the depolarization of the interventricular septum, ventricular depolarization then progresses from the endocardium through to the epicardium across both ventricles producing an R wave and an S wave. An R wave is the first positive deflection of the QRS....
A wide QRS complexThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also... is produced most often from an impulse that originates from within the ventricles. In fact, a wide QRS has a ventricular origin about 85% of the time in the general population. With those with known coronary arteryMain vessels carrying blood from the heart; the arteries have minimal elasticity and contain approximately 20% of the blood supply. Major Vessels 1. Six Second ECG Guidebook (2012), T Barill, p. 15, 190 disease, tachycardias with wide QRS complexes are indeed ventricular tachycardiaIs a cardiac rhythm characterized by rapidly occurring wide QRS complexes with absent or infrequent P waves evident; the absence of atrial kick, the lack of filling time, and the tendency for ventricular tachycardia to change to ventricular fibrillation makes... almost 95% of the time. As a general rule, if it looks like ventricular tachycardiaA cardiac rhythm with a rate above 100/minute; for example, if the impulse originates from the atria with a rate of 160/minute, the rhythm is called an atrial tachycardia. A cardiac rhythm is usually named first by the location of..., treat it like ventricular tachycardia.
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 109-110