Biomedical subjects
Publications and source records attributed to M Pauletti.
We have used pulsed Doppler to ascertain effective atrial contribution to ventricular filling in sequential pacemaker rhythm. The technique is particularly valuable when electrocardiographic evidence of atrial capture is uncertain.
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.
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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)
Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.
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Superior vena cava obstruction is described in a patient with two endocardial pacing electrodes. At necropsy a severe stenosis of the venous lumen was found at the site of intersection of the two catheters. There was no evidence of thrombus formation. Venous wall stenosis is an unusual complication of transvenous pacing and is probably favoured by the presence of two electrodes.
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Eighty-two patients, with electrodes implanted for varying periods of time, have been divided into three groups: acute (at implantation); intermediate (3 to 36 months) and chronic (37 to 124 months). In these groups, respectively 28, 26 and 28 myocardial stimulation threshold measurements have been performed. Measurements have been performed with MEEMR (Myocardial Excitation Energy Meter), an instrument deviced and built by the Institute of Elaboration of Information, CNR and University of Pisa. Microjoule has been chosen as unit of measure. More commonly used units of measure, such as threshold current in milliamp, have been calculated from values in microjoules. Mean values was 0.6 muJ in the first group, 6.9 muJ in the second one and 8.3 in the third one. Student test has been performed on such measurements, divided into groups, with the following results: p less than 0.01 between 1st and 2nd group, non significant difference between 2nd and 3rd group, p less than 0.01 between 1st and 3rd group. Such results suggest a trend toward myocardial threshold stabilization over a long period of time, as had already been hypothized by others Authors. Further useful information may be drawn from these data if they are evaluated in relation to a life-time pacemaker, as is nowadays desirable in view of recent progress in circuit technology and energy sources.
The Authors have studied the vectocardiogram in left bundle branch block, right endoventricular pacing, myocardial infarction and right endoventricular pacing, myocardial infarction and left bundle branch block. Vectocardiographic loop analysis allows the diagnosis of myocardial infarction both in the presence of endoventricular pacing and in the presence of left bundle branch block.
A case of superior vena cava syndrome is described in a patient with two endocardial pacing electrodes. At autopsy a severe stenosis of the venous lumen was found at the crossing site of the two catheters. There was no evidence of thrombus formation. Venous wall stenosis is an unusual complication of transvenous pacing and is probably favoured by the presence of two electrodes.
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