7.4
Code 7.4 — Minnesota Code 7-4: non-specific intraventricular block. The QRS duration is 0.12 s (120 ms) or more in a majority of beats, but the shape of the complex does not meet the criteria for complete left or right bundle branch block. The delay is spread throughout the ventricular muscle or the distal conduction system. Like LBBB, this code suppresses Q-wave, ST and T coding in the Minnesota system. The Novacode counterpart is NC-3.3 (code 3.31).
Causes
- Dilated or ischaemic cardiomyopathy, scar after myocardial infarction
- Severe left ventricular hypertrophy
- Hyperkalaemia — an emergency when QRS widens quickly
- Sodium-channel-blocking drugs (class IC antiarrhythmics, tricyclic antidepressants) and overdoses
- Infiltrative heart disease, hypothermia
Clinical significance
A wide QRS without bundle branch block shape often reflects diffuse damage of the ventricular muscle. In population studies and in patients with heart disease, non-specific intraventricular conduction delay has been associated with a higher risk of heart failure and cardiovascular death. Evaluation includes echocardiography, a review of medications and blood electrolytes.
if QRS widening is new and accompanied by weakness, palpitations, fainting or chest pain, or if it occurs with kidney failure, potassium-raising drugs or possible overdose.
References
- 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
- 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
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