Home > ECG findings

3.31

Novacode 3.3: non-specific intraventricular conduction delay — QRS > 110 ms without bundle branch block morphology; causes and prognosis.

Code 3.31 (Novacode NC-3.3) — non-specific intraventricular conduction delay (IVCD). The QRS complex is wider than normal, but its shape does not meet the criteria for left or right bundle branch block. The AHA/ACCF/HRS recommendations define non-specific IVCD as a QRS duration over 110 ms in adults without LBBB or RBBB morphology. The delay is located in the ventricular muscle or in the distal branches of the conduction system. In the Minnesota Code this corresponds to code 7-4.

Novacode 3Wide QRSIntraventricular conduction delay

QRS duration> 110 ms

Morphologyneither LBBB nor RBBB

Minnesota Code7-4

Key testechocardiography

Figure 1. Left: normal QRS (about 90 ms). Right: non-specific IVCD — the QRS is widened and slurred, but without the typical notched R of LBBB or the rSR′ of RBBB.

Causes

Dilated or ischaemic cardiomyopathy, previous myocardial infarction with scarring
Marked left ventricular hypertrophy
Hyperkalaemia (high blood potassium) — QRS widening can be rapid and dangerous
Drugs that block sodium channels: class IC antiarrhythmics (flecainide, propafenone), tricyclic antidepressants, overdose of some other drugs
Severe hypothermia, infiltrative heart disease

Clinical significance

A wide QRS reflects slower spread of activation through the ventricles. In population studies and in people with heart disease, non-specific IVCD has been associated with a higher risk of heart failure and cardiovascular death, often more than isolated RBBB. It is therefore a reason to check the structure and function of the heart and to review medications and blood electrolytes.

Seek urgent care

if the QRS widening is new and accompanied by weakness, palpitations, fainting or chest pain, or if it occurs with kidney failure, potassium-raising drugs or a possible drug overdose.

References

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances. Circulation. 2009;119(10):e235–e240. doi:10.1161/CIRCULATIONAHA.108.191095
Rautaharju PM, Park LP, Chaitman BR, Rautaharju F, Zhang ZM. The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression. J Electrocardiol. 1998;31(3):157–187.
Prineas RJ, Crow RS, Zhang ZM. The Minnesota Code Manual of Electrocardiographic Findings. 2nd ed. London: Springer; 2010. doi:10.1007/978-1-84882-778-3

This article is for general information and does not replace a consultation with a doctor. ECG findings must be interpreted by a physician together with symptoms and other tests.

Published on 14 May 2019