[Development of a canine model of chronic progressive right ventricular hypertension]. / Desarrollo de un modelo canino de hipertensión ventricular derecha crónica progresiva.

INTRODUCTION: Several animal models of right ventricle hypertension (RVH) have been produced through pulmonary artery banding with linen, tygon or teflon. Nevertheless few devices attempting a progressive, step by step graduated chronic development of RVH have been reported. The present study describes the results in our animal model of chronic RVH. MATERIAL AND METHODS: We designed a software programmed to obtain hemodynamic data and installed a small occlusive hydraulic device (OHD) at the pulmonary artery trunk producing a raise in the right ventricular systolic pressure (RVSP); this pressure can be modified externally through the OHD. We studied 12 healthy mongrel dogs (18 to 28 kg of weight) in the course of 6 months. Hemodynamic measurements were performed at different RVSP at two months intervals; (Baseline, 40 mmHg and 60 mmHg). RESULTS: The software was useful to analyze several hemodynamic variables at each RVSP. At 60 mmHg, the end diastolic pressure of the right ventricle (RVEDP) increased from 4.2 +/- 0.4 mmHg to 13.2 +/- 1.1 mmHg, p < 0.000, accompanied with a fall in cardiac output adjusted to the dogs weight from 0.16 +/- 0.03 L/min/kg to 0.09 +/- 0.01 L/min/kg, p > 0.000. Also an increase of the end diastolic pressure of the left ventricle (LVEDP) from 7.4 +/- 0.8 mmHg to 16.3 +/- 2.8 mmHg, p < 0.000, was observed. RVSP was maintained in chronic condition and the intraclass correlation coefficient was 0.83, P < 0.005. CONCLUSIONS: Right ventricular chronic hypertension is created. The device is useful and reliable to maintain chronic increments of RVSP. The software permits a versatile analysis.

[Helical computerized tomography of the thorax in the diagnosis of unresolved chronic pulmonary thromboembolism]. / La tomografía computarizada helicoidal del tórax en el diagnóstico de la tromboembolia pulmonar crónica no resuelta.

We assessed the diagnostic usefulness of helical CT scan of the thorax in the setting of chronic thromboembolic pulmonary hypertension by prospectively comparing the results of helical CT scan to those of the pulmonary angiogram (gold standard). We studied 40 patients with diagnosis of pulmonary hypertension of diverse etiology (mean age: 40.7 +/- 12 y.o.; mean systolic pulmonary artery pressure: 91 +/- 33 mmHg)). Thirty of these patients fulfilled the diagnostic criteria of chronic thromboembolic pulmonary hypertension and the other ten were used as controls. Diagnosis in control patients included: primary pulmonary hypertension (4); patent ductus arteriosus (2); atrial septal defect (1); rheumatic valve disease (1); ischemic heart disease (1); and acute pulmonary embolism (1). Both helical CT scan and pulmonary angiogram were part of the routine diagnostic work up of these patients, and were, performed and interpreted almost simultaneously (within one week) by a different group of investigators in a blind manner. Only the diagnostic accuracy of the method regarding central (major arteries) vascular lesions was evaluated. Helical CT scan had an overall sensitivity of 100% (29/29), and a specificity of 91% (10/11). Positive predictive and negative predictive values were 96.6% (29/30) and 100% (10/10), respectively. Overall diagnostic accuracy was 97.5% (39/40). We conclude that helical CT scan of the thorax is an excellent alternative approach for the diagnosis of major arteries lesions in the setting of chronic thromboembolic pulmonary hypertension.

[Pulmonary vascular reactivity and the development of edema in the presence of prostaglandin inhibitors in the isolated canine lobe]. / Reactividad vascular pulmonar y formación de edema en presencia de inhibidores de prostaglandinas en el lóbulo canino aislado.

UNLABELLED: Alveolar hypoxia is the most powerful pulmonary vasoconstrictor. In a previous work, we did not demonstrate significant changes in vascular reactivity and edema formation in an isolated canine lobe model during alveolar hypoxia. The purpose of this study is to define vascular pulmonary reactivity and edema formation after induction of pulmonary vasoconstriction using a prostaglandin inhibitor like tiaprofenic acid and alveolar hypoxia. Six isolated canine pulmonary lobules were instrumented and studied, all of them under two conditions (normoxia FIO2 21% and hypoxia FIO2 5%) four starting in normoxia condition and 2 starting in hypoxia condition. RESULTS: No significant changes in filtration rate were found, normoxia 0.42 +/- 0.41, hypoxia 0.37 +/- 0.51 ml/min/100 g pulmonary tissue P = NS. The arterial pressure in basal conditions was 25.1 +/- 6.21, and during hypoxia increased to 37 +/- 7.19 cm H2O (Delta 12.0 +/- 1.2 cm H2O). P < 0.001. CONCLUSION: Hypoxia vascular reactivity was significantly increased in tiaprofenic acid pretreated isolated canine lobes, no changes in pulmonary permeability was found nor increased rate in edema formation.

Preliminary results from the Mexican national telemedicine network.

A national telemedicine network was established in Mexico, based on satellite transmission. Six remote hospitals were connected during the first phase in 1997. The network applications included distance learning and administration. In addition, 476 clinical consultations were carried out in the first six months (to March 1998). Clinical problems were solved in the teleconsultation in 159 cases (33%). The patient was transferred in 217 cases (46%). The 16 most common specialties at the six remote sites accounted for 274 teleconsultations, and cardiology and orthopaedics accounted for just over half of all teleconsultations. One of the six remote sites accounted for 41% of the teleconsultations.

[Continuous spectrophotometry as a method to study pulmonary edema in isolated canine pulmonary lobe]. / Espectrofotometría continua como método para el estudio del edema pulmonar en una preparación de lóbulo pulmonar canino aislado.

The aim of this paper is to introduce the spectrophotometric method to the study of pulmonary edema in isolated ex-vivo canine pulmonary lobe preparation. This spectrophotometric method is based on the on-line measure of light transmission in a column of blood, that is proportional to hematocrit. A second light is used to follow Evans blue dyed proteins. With this method we were able to measure the amount of edema in 10 isolated canine lobes. Both the filtration and reflection coefficient of the membrane as well as the characteristics of the filtrate could be calculated. The filtration coefficient was 0.6 +/- 0.4 ml/min (1.3 +/- 0.9 ml/min/100 g pulmonary, tissue) at maximum capillary pressure and the reflection coefficient was 0.53 +/- 0.07. With the spectrophotometric method we have the capability to study different aspects of lung edema formation. This method has the advantage of being exact and independent from pressure and volume induced vascular changes. It also allows the measurement of solute transport.

[Pulmonary function in chronic ischemic cardiopathy]. / Estudio de la función pulmonar en la cardiopatía isquémica crónica.

Twenty patients with heart disease were prospectively studied. Seven of them had an old myocardial infarction and thirteen, ischemic symptoms without infarction. Pulmonary function was studied focusing on small airway disease and gas exchange abnormalities. Our results showed that a mild degree of abnormality exists as reflected by bronchial obstruction with origin in small airways, V/Q disturbed and hypoxemia. In 88% these seem to be related to left ventricular disfunction. Twenty four hours after pulmonary function test all patients underwent left heart catheterization with coronarography and ventriculography.

[Alveolar-arterial oxygen gradient in cardiopulmonary patients breathing ambient air at rest and during exercise]. / Estudio del gradiente A-a de oxígeno en pacientes cardiopulmonares, respirando aire ambiente, en reposo y en ejercicio.

The alveolar to arterial difference of oxygen [(A-a)DO2] depends on variables such as ventilation, cardiac output, respiratory exchange ratio and arterial PO2. The arterial PO2 itself depends on the ventilation to perfusion ratio (V/Q) pulmonary shunt, (a-v) O2 difference, and the metabolic status of the patient. When the alveolar-ventilation is normal, the (A-a)DO2 reflects gas exchange abnormalities and when the alveolar-ventilation is increased, the (A-a)DO2 can increase because of a decrease in PaCO2. The factors capable of altering the alveolar to arterial oxygen difference were investigated in ninety patients with pulmonary disease: (pulmonary embolism, lung fibrosis and chronic obstructive lung disease), both at rest and during exercise. At rest when alveolar ventilation was increased, the (A-a)DO2 broadened due to the decrease in PaCO2. During exercise the (A-a)DO2 also increased and the PaCO2 was not significantly modified, therefore admixture it is the result of an increase in the proportion of venous. The difference between the mixed venous and arterial PO2 decreased due to alveolar hypoventilation reducing in consequence the (A-a)DO2. We conclude that in the group studied the increase in the (A-a)DO2 is mainly due to V/Q imbalance at rest and during exercise.

Estudio de la funcion pulmonar en la cardiopatia isquemica cronica. / Pulmonary function study in chronic ischemic heart disease

Se estudiaron 20 pacientes, 7 con infarto del miocardio de mas de un ano de evolucion y 13 con cardiopatia isquemica sin infarto. En el momento del estudio no mostraban evidencia clinica de insuficiencia cardiaca y ninguno era fumador. Se estudio la funcion pulmonar haciendo hincapie en aquellas alteraciones que traducen trastorno funcional de la via aerae menor y del intercambio gaseoso. En ellos, se encontraron signos de patologia pulmonar de poca cuantia, reflejada en broncobstruccion que se manifesto por trastorno funcional de la via aerea menor, desequilibrio de la relacion ventilacion/persfusion e hipoxemia. Estas alteraciones fueron poco importantes y en el 88% probablemente secundarias a congestion pulmonar por disfuncion ventricular izquierda. Veinticuatro horas despues del estudio de la funcion pulmonar en el laboratorio, todos los pacientes fueron estudiados en el gabinete de hemodinamica mediante estudio de cateterismo cardiaco, ventriculografia y coronariografia selectiva