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question on a qrs complex

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A high voltage QRS complex can indicate ventricular hypertrophy commonly.



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LVH- Clinical Detection

The unfortunate clinical reality is that the ECG is not very accurate as a diagnostic tool for determining chamber enlargement. Even in the best of hands, the sensitivity for detecting LVH (Left Ventricular Hypertrophy) does not exceed 60% (although specificity may approach 90 to 95% when certain criteria are met).

Diagnostic accuracy for determining RVH (Right Ventricular Hypertrophy) and atrial enlargement is even less. Echo-cardiography is far superior to the ECG for diagnosing enlargement of any cardiac chamber.

Simplified Criteria for Diagnosing LVH

Deepest S wave in lead V1 or V2, plus tallest R wave in lead V5 or V6 > 35 and/or R wave in lead aVL > 12.

Patient > 35 years old.

Left ventricular (LV) "Strain" (see below).

For adults 35 or over, remembering the numbers 35 and 12 allows diagnosis of LVH most of the time when it is possible to do so by 12-lead ECG. Only one of these criteria (35 or 12) need be met to diagnose LVH. These criteria are not valid for younger patients (under 35). If "strain" is present in addition to voltage the specificity (accuracy) for true LVH is greatly increased.

Additional Voltage Criteria may occasionally be needed to diagnose LVH. We favor any of the following:

An R wave > 20 in any inferior lead (II, III, or aVF).

A deep S wave ( > 20-25) in lead V1 or lead V2.

A tall R wave ( > 25) in lead V5.

A tall R wave ( > 20) in lead V6.

"Strain" is a pattern of asymmetric ST segment depression and T wave inversion (See Figure). LV strain is most commonly seen in one or more leads that look at the left ventricle (leads I, aVL, V4, V5, V6); less commonly it can be seen in inferior leads.

If a strain equivalent pattern (See figure) occurs in association with voltage for LVH, specificity for true LVH is greatly enhanced compared to the voltage criteria alone.

What if there is a conduction defect? (See LVH + BBB)

Suspect LVH despite RBBB if the R in aVL is > 12, or the R wave in V5 or V6 is > 25.

Suspect LVH despite LBBB or IVCD, if the S wave in V1, V2, or V3 is very deep ( > 30). It is probably best not to even bother trying to diagnose RVH when LBBB, RBBB, or IVCD is present.

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You can also get a high QRS voltage in patients with thin muscular walls (i.e. atrophied pectorals and intercosals). "High voltage" QRS are not necessarily pathological but a warning from teh machine that your readings have become unreliable as the detected current is exagerated.

Tall peaks in the QRS complexes of the anterior leads can suggest LVH, but the warning "high voltage" (at least on the life packs) is not a diagnostic tool.


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Not sure if you're looking for a simpler answer or not... high QRS voltage is shown on the EKG with very tall QRS waves. The displacement of those waves (height or depth) reflects the voltage detected, so abnormally high or deep waves indicate high voltage readings.

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