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Biomedical subjects

G Mazzocca

Publications and source records attributed to G Mazzocca.

13 recordsLinked to original sources
PubMed1987

A reference data base for multilead electrocardiographic computer measurement programs.

In an effort to standardize and evaluate the performance of electrocardiographic computer measurement programs, a 15 lead reference library has been developed based on simultaneously recorded standard 12 lead and orthogonal XYZ lead data. A set of 250 electrocardiograms (ECGs) with selected abnormalities was analyzed by a group of five referee cardiologists and 11 different 12 lead and 6 XYZ computer programs. Attention was focused on the exact determination of the onsets and offsets of P, QRS and T waves. The referees performed their task on highly amplified, selected complexes from the library in a two round process. Median results of the referees coincided best with the median derived from all programs. An analysis of stability proved that the combined program median was a robust reference. However, some individual program results were widely divergent. Paired t tests demonstrated earlier onset for P and QRS (p less than 0.001), as well as later offset for P and T waves in the median 12 lead than in the XYZ results. Significant differences also existed among results obtained by programs analyzing all standard ECG leads at one time, the so-called multilead programs, and those obtained by the conventional standard three lead analysis programs. As a consequence, the derived P, PR, QRS and QT interval measurements varied quite widely among the various programs. Significant differences were also observed among measurements of Q, R and S duration. Some programs showed Q waves that were on the average 6 ms (p less than 0.001) longer than those of others. This may significantly influence diagnostic performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗
PubMed1986

Prognostic value of ventricular arrhythmias and transient ST-T changes after myocardial infarction: a two-year follow-up with ambulatory ECG recording.

The aim of this study is to evaluate the frequency and prognostic significance of ventricular arrhythmias (VA) and of ST-T changes found during 24-h ECG recording in patients who survived an acute myocardial infarction. Eighty-nine patients (2 females and 87 males) discharged from hospital after acute myocardial infarction were studied. Mean age was 52.2 years (SD +/- 10) with a range of 26-68. Serial observations were carried out at 1, 2, 3, 6, and 12 months after the acute event. Eight patients died during the first two years of follow-up, of these, 2 deaths were of noncardiac origin: one was due to gastric carcinoma and the other to pulmonary neoplasm. Of the 6 cardiac deaths, 4 were sudden and unexpected and 2 were due to reinfarction. Statistical analysis of the results obtained in the first three months of follow-up has not shown any significant correlation between pathologic patterns and cardiac death. In the second period we found a statistically significant relationship between cardiac death and multiform VPBs (p less than 0.05), CVA (p less than 0.05), and ST-T changes (p less than 0.05). More significant was the correlation between cardiac death and the presence at the same time of ST-T changes and multiform VPBs (p less than 0.01).

Adult↗
PubMed1985

Establishment of a reference library for evaluating computer ECG measurement programs.

As a result of an international cooperative project entitled "Common Standards for Quantitative Electrocardiography" (CSE), an ECG reference data base has been established with the aim of standardizing computer-derived ECG measurements. The objective of the project is to reduce the wide variation in wave measurements currently obtained by ECG analysis programs. A library of 250 ECGs with selective ECG abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T. This task was performed by a board of cardiologists on highly amplified, selected complexes from the library. A subset was examined in order to study beat-to-beat and intraobserver variability. By using a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained which proved to be highly reproducible and precise. A reference library has thereby been developed which allows testing of the performance of ECG measurement programs and is a useful instrument in establishing recommendations for more precise measurement rules and definitions.

Computers↗
PubMed1984

Clinical experience with a new dynamic display system for ambulatory ECG recordings.

The authors present the results of clinical experience with a new display for ECG signal presentation in ambulatory ECG monitoring. The new method has been devised by adding to contourography the dynamic effect produced by image movement and the perspective effect produced by pseudo-tridimensional presentation. The system has been developed using a microprocessor, a dynamic memory and an arithmetic unit which sends the signal on a CRT screen. Clinical experience, based upon 150 analyses, demonstrates the new method's marked efficiency in presenting rhythm disturbances and particularly ST-T segment alterations. Clinical validation has been performed comparing the results of 50 tapes analysed both with the new method and with different commercial systems. The new method provides useful information as to ST-T segment in 98% of cases and as to rhythm disturbances in 90%, while commercial systems reveal ST-T alterations in 84% and arrhythmias in 70% This method, being devoid of automaticity, does not yield false positives; dynamic and pseudo-tridimensional visualization of ECG signal allow the operator to perceive with high sensitivity alterations of the observed tracing.

Ambulatory Care↗
PubMed1983

[A new system for dynamic electrocardiography. First clinical trial].

The development of a reliable system for analysis of ambulatory ECG recordings, for evaluation of arrhythmias and ST-T segment changes is a great challenge for technology and cardiovascular medicine. Signal superimposition or AVSEP system, conceived by Norman J. Holter, has been widely used and is employed even in recent sophisticated devices for analysis of ambulatory ECG recordings. As an alternative way we have chosen contourography, known since 1966, enhanced by a dynamic and perspective effect (Fig. 1). Figure 2 shows the display mechanism of the ECG signal. Cardiac cycles are continuously sampled, triggered and positioned along the running time axis. The QRS complexes undergo progressive amplitude decrease while "sliding" toward a viewpoint adjustable by the operator (Fig. 3). As memory contains a fixed number of cycles, the latest cycle enters the screen while the oldest falls out. Instead of being superimposed as in AVSEP system, cardiac cycles are displayed separately. In this way it is possible to make comparisons between one cycle and another or among different areas of the ECG tracing. At any instant, the tracing can be stopped, and an intensified area of interest can be recorded on a paper strip in a standard fashion (Fig. 4). A clinical comparison has been performed between this device and two different commercial systems; 25 tapes, 24 hours each, have been separately analyzed by two cardiologists with the Avionics system and 25 with the Pathfinder, and then with the new system. Each operator was not aware of the results of the other one.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory Care↗