57) (a) A PR interval of > 200 msec was considered PR prolongation; a QRS interval of [greater than or equal to] 120 msec was considered QRS prolongation.
OBJECTIVE: We evaluated the association between a history of arsenic exposure from drinking water and the prolongation of heart rate-corrected QT (QTc), PR, and QRS intervals.
Fifty-five patients who had QRS intervals
less than 120 msec were evaluated for the prevalence of septum, lateral and papillary muscle dyssynchrony and its association with functional MR.
The trial also showed that even patients with narrow QRS intervals
also obtain a small benefit from ICD therapy, CMS noted in its coverage decision.
Although the benefit appeared to be greater in patients with a QRS interval
longer than 0.
In light of biologic probability that QRS interval
may be a limiting factor in the benefit of defibrillators, it was not imprudent to await more data before approving coverage of an expensive technology in that group, he said.
And while it's true that the wider a patient's QRS interval
, the greater the mortality, it's also the case that MADIT II patients having a QRS shorter than 120 milliseconds also had better survival with an ICD.
Thus patients with the widest QRS interval
(greater than 120 milliseconds) are likely to have the greatest benefit--the lowest mortality--after ICD implantation.
Ventricular pacemakers placed in the left and right ventricles in patients with bundle branch block and a QRS interval
greater than 140 milliseconds have been shown to reorganize that ventricular contractility.
Measurement of the QT interval should be as critical as measurement of the PR and QRS intervals
Atrioventricular blocks, sinus bradycardia, prolongation of the QT and QRS intervals
and Torsades de Pointes were reported in hypothyroid patients (1, 3, 4).
The measurements of QT, JT and QRS intervals
were all comparable between the two groups (p>0.