[Electrocardiographic findings in a school-age population using a computerized system: calculation of standard norms for heart rate and PR, QRS, and QT intervals]. / Rilievi elettrocardiografici in una popolazione in età scolare mediante un sistema computerizzato: calcolo degli standards di normalità per la frequenza cardiaca e gli intervalli P-R, Q-R-S, Q-T.

We evaluated some ECG parameters (HR, P-R, Q-R-S, Q-T) in a healthy school-age population. One-thousand-eight-hundred and ninety children ranging in age from 5 to 12 coming from different zones of the city of Naples were studied. On physical examination all subjects were free from cardiac disease. A computerized ECG (Muse 12SL System Marquette) was performed on every subject. One-hundred and seventy-four of the 1890 children were excluded from statistical analysis because of ectopic rhythm (junctional rhythm or wandering pacemaker) or poor quality of the recording. Of the 1716 children included in the study, 837 were male and 879 were female. The computerized ECG 12SL System Marquette registers an ECG record consisting of all 12 classical ECG leads acquired simultaneously over a 10 second period. Each individual complex can be analyzed in all leads by the computer. An interpretation using this extended record, along with an ECG record of conventional length, is presented to the physician for review. The first step in computerized ECG analysis is Q-R-S identification, then P wave identification, beat classification, rhythm analysis, morphology analysis, complex alignment and computation of median complex. All parameters were divided for sex and age and gathered into tables. The variability of P-R, Q-R-S, Q-T versus HR were also evaluated. The following conclusions were drawn: 1) Sex is a very important variable in the parameters examined. Males have a much slower HR, greater Q-R-S duration, and longer Q-T interval when compared to females. 2) As age increases, HR slowly decreases, while P-R, Q-R-S and Q-T intervals increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive electrophysiological evaluation of calcium antagonist long-term therapy.

The evaluated effects of oral administration of verapamil, diltiazem, and nifedipine in patients with first degree A-V block by using a new noninvasive technique: signal averaged ECG. The study group consists of 5 females and 3 males ranging from 52 to 70 years old. All patients showed a first degree A-V block at surface ECG and an abnormal A-V time (suprahisian lengthening) during signal averaged ECG (SAECG). Verapamil 240 mg/daily, diltiazem 180 mg/day and nifedipine 30 mg/day were given separately for a week followed by a wash out period of 5 days before giving next drugs. An ECG and SAECG were performed before and after every administration. PR, A-H and H-V interval were evaluated in every recording. Verapamil and diltiazem induced a significant lengthening of A-V conduction (PR increase was 15.4% and 15.1%, respectively). No significant modification appeared after nifedipine. Our data, using a noninvasive technique, agreed with values of previous invasive evaluations. We suggest precaution in using verapamil and diltiazem in patients with BAV 1 degree and advise a selective use of calcium antagonist therapy.