[Fundamental bases of digital information processing in nuclear cardiology (III)]. / Bases fundamentales del procesamiento digital de la información de la cardiologia nuclear (III).

This article describes the transformation of the gamma-camera images into digital form. The incidence of a gamma photon on the detector, produces two voltage pulses, which are proportional to the coordinates of the incidence points, and a digital pulse, indicative of the occurrence of the event. The coordinate pulses passes through a analog-digital converter, that is activated by the pulse. The result is the appearance of a digital number at the out-put of the converter, which is proportional to the voltage at its in-put. This number, is stored on the accumulation memory of the system, either on a list mode or on a matrix mode. Static images can be stored on a single matrix. Dynamic data can be stored on a series of matrixes, each representing a different period of acquisition. It is also possible to capture information on a series of matrixes syncronized with the electrocardiogram of the patient. In this instance, each matrix represents a distinct period of the cardiac cycle. Data stored on the memory, can be used to process and display images and quantitative histograms on a video screen. In order to do that, it is necessary to translate the digital data on the memory to voltage levels, and to transform these on light levels on the screen. This, is achieved through a digital analog converter. The reading of the digital memory must be syncronic with the electronic scanning of the video screen.

[Electrical changes in experimental diastolic and mixed overloads of the right ventricle]. / Cambios eléctricos en las sobrecargas experimentales diastólicas y mixta del ventrículo derecho.

The paper describes the electrical changes in 115 mongrel dogs with exposed heart and open pericardium, during the gradual development of diastolic and combined (diastolic and systolic) overloading of the right ventricle. Ventricular overload was produced by means of a constant venous infusion of saline solution: up to 12 liters in 3 hours and half. In all cases, right intraventricular conduction disturbances, of either proximal or distal type, appeared. Right blocks were classified on the base of the topography of the ventricular activation delay. They were correlated with the hemodynamic adaptation. The results of this study allow us to formulate the following main points: 1) Disturbances of the right intraventricular conduction during experimental diastolic and combined overloading of the ipsilateral ventricle, seem to be due to a distention of the ventricular specialized fibers; 2) proximal right blocks are related to a global dilatation of the ventricular chamber, secondary either to a quick overloading or to a decrease in the myocardial capacity for adaptation; 3) distal right blocks are caused more frequently by a distention of the anterolateral portions of the free right ventricular wall, where the right middle subdivision is located.

[Structure and organization of digital systems for processing information in nuclear cardiology]. / Estructura y organización de los sistemas digitales para el procesamiento de la información de la cardiología nuclear. (I).

This article describes the internal structure and organization of digital systems in use for processing the data information obtained through the in vivo applications of radioactive tracers in cardiology.

[Electrophysiological evaluation of occlusal splint treatment of patients with temporomandibular joint dysfunction]. / Valoración electrofisiológica de tratamiento con férula oclusal en pacientes con disfunción de la articulación temporomandibular.

Blink reflex time records were obtained from patients with temporomandibular joint disfunction (TMJD), before and after treatment with occlusal splint, since blink reflex time helps to study the trigeminal-facial functional relationship. Results suggest that the impaired sensory-motor function in the trigeminal-facial complex of TMJD patients, may return to normal latency values following such treatment.

[Correlation between ventricular volume calculated manually and by computer]. / Correlación entre los volumenes ventriculares calculados manualmente y por computadora.

We present here a program of ventricular volumes measurements in which an area-lenght procedure and a digital computer were used. The results were compared with those obtained by the manual method using the same formula. The correlative estatistical analysis of these results showed a high index of 0.95 when compared to the telediastolic volumes obtained by both technics, while the index reached 0.99 in reference to the telesistolic volumes and the ejection fraction.

[Electro-vectorcardiographic aspects of diastolic and mixed overloads of the right ventricle]. / Aspectos electrovectocardiográficos de las sobrecargas diastólica y mixta del ventrículo derecho.

We studied 400 cases of isolated atrial septal defect without severe pulmonary hypertension, in which the diagnosis was established by the hemodynamic data and it was proven by surgical findings in 257 instances. High fidelity unipolar thoracic and intracardiac records, as well as vectorcardiographic curves in three planes, were obtained. Different types of right ventricular conduction disturbances, which were present in all cases, as well as certain electro-vectorcardiographic aspects related to ventricular depolarization and repolarization, were analyzed. Mean angles of the resulting vectors at 60 msc of the ventricular activation, were determined relating to the types of block. The following points should be emphasized: Besides the right proximal blocks, which are more frequent, right distal ones can also be diagnosed by the presence of slurred R wave and delayed onset of the intrinsicoid deflection in only some right leads. The monofascicular and parietal right blocks are observed when the diastolic overload of the ipsilateral ventricle is low. The activation time of the anterior inferior right septal mass generally permits an objective classification of the degree of a right proximal block. The prolonged Q-Tc interval only in right leads, seems to be a function of the magnitude of the right ventricular diastolic overload.

[Policy guidelines and practical considerations for the development of technology at the Instituto Nacional de Cardiología de México]. / Lineamientos doctrinarios y consideraciones prácticas para el desarrollo de tecnología que se realiza en el Instituto Nacional de Cardiología de México.

In order to face the current economical problems of the country, our Institute has intensified its efforts to replace the imports of medical goods by developing its own medical technology. This article summarizes what we have achieved in this field and describes the rules to be followed in the future. We describe the program on the designing and development of heart valve prosthesis together with an hydraulic-electrical system to test them. In the field of computed instruments, we have developed a system of "synchronos color pictures" to be applied in nuclear medicine. In the field of electrocardiography; an EKG paste, a computed program for automatic EKG interpretation and a "filter" of the 60 cycle interference. The Institute is engaged in the designing of a sophisticated EKG machine at low cost, and EKG tracing simulator for teaching purposes. These programs have been shared with others institutions of the country.

[Electromyographic activity (EMG) of masseter and temporal muscles in edentulous patients before and after complete dentures]. / Actividad electromiográfica (EMG) de los músculos masetero y temporal en pacientes edéntulos antes y después del uso de prótesis completa.

Electromyographic records from the temporal and masseter muscles of 19 edentulous patients were made, before and 30 days after wearing complete dentures. The purpose of this study was to determine the electromyographic changes: The amplitude of electromyographic records from de temporal muscles decreased, while those from the masseter muscles increased. These results suggest that the use of complete denture provokes electromyographic changes by increasing the occlusal vertical dimension and, thus, periodical electromyographic records from temporal and masseter muscles could be useful for determining the time for complete denture change.

Improved automatized recording of masticatory reflexes through analysis of effort trajectory during biofeedback.

Tap and sound evoked inhibitory motor reflexes within masseteric EMG were studied by means of a new technique that uses real time analysis of the trajectory followed during voluntary occlusal effort, controlled through visual biofeedback, in order to stimulate on exactly the same activity background. This technique uses a two computers system, doing parallel processing to support data acquisition, video indication, calculus of the pursued trajectory and evaluation of it. Stimuli were automatically delivered when the effort's trajectory fulfilled a set of conditions. Denomination of reflexigram (RFXG) is proposed to the cumulative, rectified and filtered EMG's series so recorded. Normal morphologies of RFXG were established on a 90 normal patients group. Clear clinical correlations were also found within two groups: 30 bruxists and 50 with temporomandibular joint dysfunction.

Valoración electrofisiológica de tratamiento con férula oclusal en pacientes con disfunción de la articulación temporomandibular / Electrophysiologic evaluation of treatment with occlusal splint in patients with temporomandibular joint dysfunction

En el presente trabajo se obtuvieron los registros de potencial provocado por la técnica de reflejo de parpadeo en pacientes con disfunción de la articulación temporomandibular (DATM) previo y posterior al tratamiento con férula oclusal. Dicha técnica explora el complejo trigémino facial (sensorial y motor respectivamente), el cual participa en la modulación de la actividad motora de los músculos que mueven la articulación temporomandibular. Los resultados muestran una disminución de las latencias de los componentes del potencial posterior al tratamiento, las cuales se encontraban aumentadas antes del mismo. También indica una participación de estructuras a nivel central en la DATM, así como una posible utilidad de la técnica de estudio utilizada en la valoración de la misma