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Biomedical subjects

G Jarry

Publications and source records attributed to G Jarry.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Doppler echocardiographic study of mitral and aortic flow at various rates and atrioventricular intervals in patients with dual chamber pacemakers].

The aim of this study was to measure the changes in mitral and aortic blood flow induced by rate changes and different atrioventricular intervals in dual chamber pacemaker patients. Ten totally pacemaker dependant patients were studied under basal conditions, in double atrial and ventricular stimulation mode, by pulsed Doppler recordings of mitral and aortic flow, at three different pacing rates (80, 100 and 120/mn) and with three different atrioventricular intervals at each rate (short, 90 or 115 ms; medium, 165 or 190 ms; and long, 240 ms). The increase in pacing rate and prolongation of the atrioventricular interval significantly shortened the duration of mitral flow. Increasing the pacing rate induced a significant fall in stroke volume measured from the aortic flow. The optimal atrioventricular interval tended to shorten when the pacing rate was increased; a long atrioventricular interval had a deleterious effect on stroke volume compared with medium and short atrioventricular intervals; however, the difference between the short and medium atrioventricular intervals was not statistically significant even at 120 mn. These observations emphasise the hemodynamic advantages of shortening of the atrioventricular interval of dual chamber pacemakers when the pacing rate increases.

Aged↗
PubMed1989

In vivo transillumination of the hand using near infrared laser pulses and differential spectroscopy.

In vivo dual wavelength differential spectrography was performed on the hand of an adult male, using a collimated transillumination device. A pulsed laser with sufficiently high peak power and sufficiently low energy was employed so that transillumination could be realized without thermal damage. Spectrochemical analysis based on the absorbance of oxygen transporting molecules (OTM), i.e. haemoglobin in blood vessels and myoglobin in muscles, was performed along a 70 mm scanning line within the near-red infrared range. The two wavelengths used (675 and 800 nm) were chosen on the basis of the absorption spectrum of haemoglobin. The profiles computed with differential spectrography data related to the oxygen saturation of OTM are closely correlated with X-ray densitometry of the most vascularized tissues in the hand along the scanning line. In addition, at 675 nm, the profiles are rapidly modified as a function of the oxygen supply to the hand. Considering the accuracy obtained for the spatial localization of the OTM redox state, it is expected that these results could be applied to imaging.

Adult↗
PubMed1989

[Sinus rhythm and standard deviation in cardiac cycles. Influence of myocardial status and beta-blocker treatment].

The efficacy of beta-blockers in preventing sudden death after myocardial infarction would seem to be greater in patients with cardiac failure and proportional to the reduction in heart rate induced by these drugs. In addition, a reduction in heart rate variability measured by the standard deviation from the average cardiac cycle over 24 hours has been reported to be an independent bad prognostic factor after myocardial infarction. This study compares the heart rates and the standard deviations from the mean cardiac cycle over 24 hours in 41 patients divided into 3 groups of comparable age (group I: normal subjects, n = 15; group II: hypertrophic cardiomyopathy without cardiac failure, n = 13; group III: cardiac failure, n = 13) before and after administration of acebutolol (10 mg/kg). The average 24 hour heart rates, the maximum 8-hour diurnal and minimum average 4-hour nocturnal heart rates, day-night ratio and standard deviations from the average 24 hour heart rate and at the hours of maximum and minimum average heart rates were measured by Holter monitoring with an ATREC II system. The 24 hour heart rates were slower in groups II (-18.1 p. 100) and III (-19.1 p. 100) than in group I (-9.5 p. 100), p less than 0.01, the basal heart rates being comparable and the heart rates after acebutolol being significantly lower in groups II and III. The degree of change was comparable during the diurnal and nocturnal periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗
PubMed1989

[Infarction with angiographically normal coronary vessels. (20 cases)].

Over 8 years, 20 cases of infarction with normal coronary angiography have been reported, representing 0.9% of the patients who underwent a coronary angiography after a myocardial infarction. The main characteristics of these patients are compared with those taken from the literature. The occurrence of this disease mainly depends on the age: especially higher when the patients are younger, ranging between 1 and 4% in major series, but it may reach 25% in case of infarction occurring before the age of 30. Therefore, this entity mainly affects young patients (mean age in the literature: 34.3 years), with a large proportion of women (27%). The main risk factor is smoking, found in 3 out of 4 men an more than half of the women; on the contrary, hypercholesterolemia and arterial hypertension are only seldom found. In women, administration of estro-progestative medications in mentioned in almost every other case. Coronary heredity is mentioned in one out of 3 cases. In 68% of the cases, the infarction is the original manifestation and frequently occurs during stress: 60 p. cent of the cases. The site of the necrosis is insignificant. Mortality is low: 2 p. cent but in 5 p. cent of the cases, the course may be complicated by recurrence or heart failure. According to recent findings on coronary angiography during the acute phase, the pathogenesis could involve an arterial coronary thrombosis, perhaps developing on minimal coronary lesions, caused by a spasm and/or a platelets hyperaggregation; then this coronary thrombosis is revascularized.

Age Factors↗
PubMed1988

[Asymptomatic and transitory electrocardiographic changes in the 24 hours following coronary transluminal angioplasty].

Fifty patients underwent a 24-hour Holter system recording immediately after successful coronary angioplasty. Only those patients who had been "successfully" dilated and who, during the following 2 days, had remained totally symptomless and without changes in standard ECG were selected. Arrhythmias occurred in 18 patients: 12 had supraventricular arrhythmia, including 3 prolonged attacks of tachyarrhythmia due to atrial fibrillation; 6 had ventricular arrhythmia, with numerous extrasystoles in 5 cases and bursts of ventricular tachycardia in 1 case. Changes in ventricular repolarization were recorded as: (1) isolated T-wave modification (11 patients), and (2) ST-segment depression (11 patients) reaching or exceeding 2 mn in 5 cases and lasting from 4 to 33 minutes. These silent and transient electrical abnormalities were observed mostly during the 12 hours which followed transluminal angioplasty, and particularly after dilatation of the right coronary artery. The physiopathological mechanisms of these changes are uncertain, but their occurrence has no influence on mid-term results, i.e. the follow-up coronary arteriography at 6 months.

Adult↗
PubMed1988

[Echocardiographic aspects of pericardial metastases. Apropos of 7 cases].

Modern two-dimensional imaging is of such quality that echocardiography is now capable of detecting intrapericardial formations. Three morphological types of abnormal intrapericardial echoes have been described: round masses, mattresses and linear echoes. These have been observed in effusions of various origin and seem to be lacking in aetiological specificity. In order to determine more precisely the echocardiographic signs of pericardial metastases, the authors have analyzed 7 cases of intrapericardial masses visualized in a series of 10 patients with metastatic pericardial effusion and examined in two-dimensional mode. These were echogenic and dense masses implanted on the pericardium and subject to cyclic movements linked with those of that membrane. Morphologically, they fell into two categories: round and sessile masses (6 cases) 8 to 23 mm high and 22 to 48 mm wide at their implantation; they were found mostly opposite the cardiac apex (4 cases) and/or in the lateral wall of the right ventricle (3 cases), oval formations (2 cases) which were 70 mm long and 17 mm wide in one case and 50 mm long and 15 mm wide in the other. One patient had two masses of different shapes. A review of the literature showed that these two echocardiographic images corresponded to two macroscopic types of pericardial invasion: either tumoral nodules or infiltration plaques betraying a diffuse invasion of the pericardium. All masses observed by the authors were located on the visceral leaflet of the pericardium. This predominantly epicardial location might be due to the visceral leaflet being selectively invaded by retrograde lymphatic embolization from the mediastinal lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Metastatic pericardial effusions. Apropos of 12 cases. Review of the literature].

The authors report 12 cases of metastatic pericardial effusions with clinical manifestations. Primary bronchial cancer is the most frequent with 7 cases; in 3 of these patients, the original manifestation is a tamponade. The contributions of sonocardiography to the diagnosis are analyzed: evaluation of hemodynamic tolerance and visualization within the effusion, in 4 out of 7 patients undergoing bidimensional sonocardiography, of dense masses, implanted on the visceral layer of the pericardium; the frequent epicardic location of these metastases may be explained by preferential invasion of the visceral layer by retrograde lymphatic route. The advantage of pericardial cytology is discussed. From the therapeutic standpoint, a pleuro-pericardial window or tetracycline instillation tend to prevent a recurrence of the effusion and the risk of tamponade; the neoplastic process is controlled with local and/or general chemotherapy and radiotherapy; therapeutic strategy depends on the sensitivity of the primary tumor. The prognosis remains very dim with a mean survival of 3.7 months in our series.

Adult↗
PubMed1987

[Significance of an upward shift of the ST segment during an exercise test].

The objective of this study is to investigate the significance of the occurrence of an upward shift of the ST segment curing a stress test in patients with no previous history of myocardial infarction. Over 10 years, totalling 9,500 stress tests, we have collected 10 cases. They always concern men including one with angina on exertion, one with spontaneous angina, one with spontaneous angina occurring at the end of an intense stress, and 7 with mixed angina. None of them had a previous history of myocardial infarction or documented spastic angina. The upward shift of the ST segment occurred 9 times during stress and once during recovery. 9 patients had a coronary arteriogram with in 8 cases severe fixed coronary lesions. The patient with the upward shift of ST during the recovery period had a normal coronary arteriogram with a positive methylergometrin test. There is a good correlation between the appearance of an upward shift of ST during stress in the anterior derivations and a significant involvement of the anterior interventricular artery. In our series, there were no complications, especially myocardial infarction, in the immediate period following the stress test. 7 patients underwent an aorto-coronary by-pass. The 10 patients are presently asymptomatic after a 47 months follow-up. The occurrence of an upward shift of ST during stress, in the absence of a previous history of myocardial infarction, represents in more than 80 p. cent of the cases the existence of severe coronary lesions leading to hospitalization and the immediate performance of a coronary arteriogram.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Scanning spectrophotometry for the dynamic study of tissue respiration in intact organs.

For use with intact perfused organs a spectrophotometer system has been developed, both for dual-wavelength absorption measurements and for spectral scanning. A monochromator is used for illumination and scanning in the visible and near infrared. Optic fibres conduct light to the specimen under examination and from the specimen to a detecting photomultiplier. System control is exercised by a microcomputer, which also processes the collected data. The performance of the system on isolated perfused rat heart is demonstrated, in the spectral scanning mode and in the dual-wavelength mode, by studying simultaneously the kinetics of cytochrome aa3, and myoglobin oxidation-reduction.

Animals↗
PubMed1984

A simulation method for the study of laser transillumination of biological tissues.

The Monte-Carlo method is employed to simulate the illumination of a blood slab by a continuous laser. It is assumed that the geometry of the medium is bidimensional and that scattering or absorption takes place only when a photon strikes a red blood cell. The parameters involved in the calculations concern the photons free path lengths between two collisions, the scattering angles and the absorption probability at collision. These parameters are assessed according to experimental or literature data. Fortran programs allow the computation of diffuse and collimated transmittances (Td and Tc, respectively), of transmittance measured with an optic fiber Tf and of reflectance R. The variations of Tc and Tf with blood thickness are in accordance with established laws. Moreover, measured and computed reflectances change with hematocrit ratio in a similar way. This work demonstrates that the Monte-Carlo method is a simple reliable tool which can be used to provide a realistic model of laser penetration in complex biological structures. Moreover, this method will permit investigations in laser tomo-spectrometry by providing a useful simulation of the interaction of ultrashort light pulses with biological media.

Animals↗
PubMed1984

Imaging mammalian tissues and organs using laser collimated transillumination.

Images of mammalian organs were built up using a Laser collimated transillumination device equipped with a bidirectional scanning setup. A microcomputer was used to run the scanning process, acquisition of detected signals and images restitution. The images featured a satisfactory resolution of optical discontinuities on both sample surfaces. Light scattering within biological tissues restricted the spatial discrimination encountered with geometrical selection approach. By combining space and time resolution at various wavelengths, the production of an efficient tomospectroscopy could be envisaged.

Animals↗
PubMed1984

Overall myocardial energetics in physiological conditions and in acute volume overloading.

Left ventricular heat production (PH,lv) was compared with myocardial O2 consumption (P met O2) and mechanical parameters in intact anaesthetized dogs before and after acute volume overload induced by a perfusion of LMW dextran. From myocardial blood flow and coronary arterio-venous temperature differences, the coronary heat loss was determined. Thermodilution techniques were used to estimate the ratio between heat carried away by the coronary system and total heat production as the left ventricular volumes. Compared with P met O2, PH,lv bore a linear correlation. Heat production per beat was highly correlated to mean systolic wall force, midwall circumferential length, midwall fibre shortening and mean circumferential shortening rate (MCSR). Mechanical efficiency computed from heat production (EH) appeared to be very close to the efficiency computed from oxygen consumption (EO). Acute overload was characterized by a very large increase in both stroke volume and MCSR. The dramatic increase observed in heart external power was accompanied by a moderate increase in PH,lv and mechanical efficiency. Nevertheless, the changes in efficiency appeared to be strongly dependent upon the changes observed in heart rate (HR). When HR was increased, the heat production per beat was moderately decreased and efficiency was drastically improved. Conversely, dogs in which HR remained stable exhibited a marked increase in the energetic cost of each beat, with efficiency being practically unmodified. Thus, since myocardial energetics is involved in acute volume overload, two possible means of adaptation may be considered: (a) tachycardia may alleviate the energetic cost of each beat, thus improving heart mechanical efficiency and (b) conversely, if HR remains stable, it may do so at the expense of the energetic cost of the myocardium for each beat, with efficiency not actually being enhanced.

Animals↗
PubMed1983

[Echocardiography in the diagnosis of pericardial effusion and tamponade].

Fifty-seven patients who had presented pericardial effusions, compressive in ten cases, were subjected to M. mode echocardiography in order to identify specific signs of cardiac tamponade during major effusions. Certain criteria were of no diagnostic value: right and left ventricular diameter, mitral valve opening amplitude, and aortic diameter (p greater than 0.1). Apart from known hemodynamic and clinical signs, one must bear in mind two echographic signs that are specific for tamponade and disappear after drainage: protosystolic notching on the anterior wall of the right ventricle appearing 0.04 s after QRS, and a slope EF less than 50 mm/s.

Adult↗
PubMed1983

[Chylopericardium, chylothorax and cystic lymphangioma. Review of the literature apropos of a case].

One case of chylopericardium associated with chylopneumothorax is reported. Published data make it clear that the pathogenesis of effusions of chyle is imperfectly known and still highly hypothetical. With the exception of tamponade, there are few pathognomonic and dramatic signs. TM and cross-sectional echography is of paramount importance, since it provides a qualitative and quantitative diagnosis of effusion, the nature of which is determined by chemical analysis. Effusions of chyle may be idiopathic or may developed after oesophago-cardio-pulmonary surgery, or even after blockade of lymphatic vessels or as a result of increased lymphatic flow rate or pressure. Although the course of the disease is usually favourable, infectious or haemodynamic complications (e.g. tamponade or constriction) may aggravate the prognosis. Treatment is exclusively surgical and consists of partial pericardectomy, which is unquestioned. There is no consensus of opinion about simultaneous ligature of the thoracic duct.

Adult↗
PubMed1983

[Predictive value of the exercise test after primary infarction].

The predictive value of exercise stress testing was assessed by correlating the results with coronary angiography in a group of 100 patients 50 with inferior and 50 with anterior wall infarction. The following observations were made: --The exercise ECG was positive in 57 p. 100 of cases, more commonly in the inferior infarction group (74 p. 100), ST depression representing over 3/4 of the responses to exercise. On the other hand, the test was only positive in 40 p. 100 of anterior wall infarctions, ST depression again being the most commonly recorded response (65 p. 100). --The overall incidence of post-infarction angina was 45 p. 100; it was more common after inferior (70 p. 100) than anterior infarction (22 p. 100). --Multivessel disease was also more severe in the inferior infarction group (86 p. 100) than in anterior infarction (46 p. 100). However, ventricular aneurysms were twice as common in the anterior infarction group. --Exercise testing detected 80 p. 100 of cases with multivessel disease, especially when the LAD artery was involved, in the inferior infarction group. In the anterior infarction group, almost 50 p. 100 of patients with multivessel disease were not diagnosed. Despite an overall sensitivity of 73 p. 100 the predictive value of exercise stress testing was excellent (84 p. 100). In conclusion, in the presence of persisting angina after myocardial infarction coronary angiography should be performed to determine the severity of the multivessel disease. Exercise stress testing is a useful but imperfect method of detecting this high risk group. Its predictive value is however better in inferior (94 p. 100) than in anterior wall infarction (65 p. 100). Persisting angina was found to be a parameter of very high specificity (100 p. 100) for the presence of multivessel disease.

Adult↗