Diagnostic criteria

  The QRS width is equal to or more than
110 ms in adults,
90 ms in children of ages 8-16 years,
80 ms in children under 8 years of age.

  The ECG findings do not fulfill the criteria for right bundle branch block or left bundle branch block.

  If precordial leads resemble RBBB and limb leads resemble LBBB (or vice versa), it is also considered as intraventricular conduction disturbance.




Clinical significance
  A recent retrospective study examined 152,479 patients who underwent noncardiac surgery. It was concluded that patients with preoperative intraventricular conduction defect (including left bundle branch block) are not at greater risk of postoperative in-hospital death or postoperative myocardial infarction compared with patients with other ECG abnormalities.



References

  Am J Cardiol 2018;121(8):997-1003.

  Circulation 2009;119:e235-e240 .





ECG 1. Intraventricular conduction disturbance.
The ECG findings do not fulfill the criteria for right or left bundle branch block (LBBB).
By definition, lead I does not show q waves in LBBB.

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ECG 2. The ECG above belongs to a patient with dilated cardiomyopathy and normal coronary arteries.
Intraventricular conduction disturbance, left axis deviation and negative T waves in the anterolateral leads are seen.

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ECG 3. First degree AV block (long PR interval) and intraventricular conduction delay.

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ECG 4. The ECG above is from a middle-aged woman with severely depressed left ventricular systolic function and shows
intraventricular conduction delay with mild PR interval prolongation (1st degree AV block).

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ECG 5. Intraventricular conduction delay from another patient. The rhythm is atrial fibrillation.

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ECG 6. Intraventricular conduction delay in a 77 years-old man with unstable angina pectoris.
Coronary arteriogram showed 3-vessel disease.

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