![]() Looking at the precordial leads, the r wave usually progresses from showing a rS-type complex in V 1 with an increasing R and a decreasing S wave when moving towards the left side. The R wave may be prolonged if the ventricle is enlarged, and may be abnormally high (indicating strong voltage) if the ventricular muscle tissue is hypertrophied. Most of the ventricle is activated during the R wave. The first upward deflection of the QRS is called the R wave. A Q wave 1 with a concordant positive T wave in the absence of a conduction defect.R wave ≥ 0.04s and R/S ≥ 1 in V1 and V2 with a concordant positive T wave without any conduction defectĬauses of Q Waves in the Absence of Myocardial Infarction.Q wave ≥ 0.1 mV in depth and ≥ 0.03 s in duration in at least two contiguous leads (I, aVL, V5, V6 V2, V3 V3, V4 or II, III, aVF).Pathological Q waves are defined as one of the following: A Q wave may also reflect septal hypertrophy in hypertrophic cardiomyopathy ( HCM). Q waves can be seen on the electrocardiogram following necrosis of the myocardium such as seen in acute MI or the replacement of electrically active tissue with electrically inert tissue as seen with Chagas disease. Q waves are “significant” if they are greater than 1 box in width (longer than 0.04 msec) OR are larger than 1/4 of the R wave. Qs are also generally innocent in lead III and lead V1 if no other abnormality is seen. “Septal Qs” are normal in I, F, V5 and V6. This activation goes left - away from lead I - and is therefore negative on the ECG. This is the early activation of the septum. For example in lead I, a Q less than 1/4 of the R height, and less than one box wide, is considered normal. The electricity spreads from right to left through the septum. ![]() The Q wave represents activation of the ventricular septum. ![]() If the first deflection of the QRS is downward, it’s called a Q wave. Widening of the QRS complex may reflect delayed conduction in the His, bundle branch or purkinje conduction system. The QRS complex represents electrical activation of the ventricle. 3.1 Causes of a Wide QRS Interval or a Prolonged QRS Interval.2.2.3 EKG Changes of Prior Myocardial Infarction.2.2.2.3 Wolff-Parkinson-White (WPW) Pattern/Syndrome.2.2.2 Conditions that Mask Q waves in the Presence of Myocardial Infarction.2.2.1 Causes of Q Waves in the Absence of Myocardial Infarction.Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. Risk calculators and risk factors for QRS complexĮditor-In-Chief: C. US National Guidelines Clearinghouse on QRS complexĭirections to Hospitals Treating QRS complex Ongoing Trials on QRS complex at Clinical Articles on QRS complex in N Eng J Med, Lancet, BMJ
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