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Biomedical subjects

G Georgiopoulos

Publications and source records attributed to G Georgiopoulos.

16 recordsLinked to original sources
PubMed1986

[Thyrotropic function in patients with a hypothalamic or pituitary tumor. Possibility of the secretion of a TSH with reduced biological activity].

Thyrotropic function was studied in 100 patients with hypothalamic or pituitary tumours before treatment. Eighteen patients with thyroid deficiency showed no signs of primary hypothyroidism. This was also showed in 4 other hypothyroid patients who had pituitary tumours studied later on. Only 4 of these 22 patients had TSH deficiency. The other 18 had normal or high plasma TSH levels, and the TSH response to TRH was normal but often delayed and/or prolonged. This pattern, suggestive of secretion of TSH with reduced biological activity, might however be due to other factors. Tumoral invasion of the hypothalamus, present in these 18 cases, could reduce secretion of TRH and dopamine. Hypothyroidism would then be secondary to TRH deficiency if TRH is considered to have a direct thyroid-stimulating action, and, like dopamine deficiency, could contribute to maintaining normal or high TSH secretion.

Adenoma↗
PubMed1983

Subcostal M-mode computerised echocardiography. An alternative or complementary approach to parasternal echocardiography?

Subcostal M-mode echocardiography has been suggested as a method for assessment of left ventricular size and function. Parasternal and subcostal measurements (direct and derived) of left ventricular function were compared in 30 healthy young subjects. We calculated instantaneous left ventricular diameter and wall thickness every 10 ms for both the subcostal and parasternal approaches using a computer program for echocardiographic digitisation and compensation. All variables were filtered to calculate instantaneous first derivative (velocity) and logarithmic derivative (normalised velocity). The program provided normal values for computerised variables of left ventricular function from the subcostal approach. It was found that there was no identity and no correlation or a poor one between subcostal and parasternal left ventricular internal diameters and volumes. The parietal wall thickness was significantly greater using the subcostal approach, and the comparative velocities study showed striking variations between the two approaches, especially in diastole, where the peak lateral wall thinning rate was 20% lower than the posterior thinning rate. We conclude that for a normal and young population, the subcostal and standard parasternal data cannot be used interchangeably for precise studies of left ventricular function. The subcostal approach, however, provides useful complementary information about lateral wall motion.

Adult↗
PubMed1982

Retrograde coronary sinus perfusion: a safe alternative for ensuring cardioplegic delivery in aortic valve surgery.

During aortic valve surgery, cardioplegic solution is delivered through direct cannulation of both coronary ostia. Since this approach may cause an intimal injury leading to acute dissection or late ostial stenosis, we have evaluated retrograde coronary sinus perfusion (RCSP) as a means of delivering cardioplegia in 12 patients undergoing aortic valve replacement. The retroperfusion of the cardioplegic solution was performed with a balloon-tipped catheter inserted into the coronary sinus through the right atrium. The perfusion pressure averaged 40 mm Hg. Twelve patients undergoing antegrade coronary perfusion served as controls. Both groups were matched for preoperative and intraoperative data. The postoperative evaluation focused on hemodynamic status, as evidenced by serial measurements of right-sided pressures and cardiac output at 1, 6, 12, 18, and 24 hours after operation. The stroke volume index and the left ventricular and right ventricular systolic stroke work indexes were then calculated. There was no statistically significant difference between the two groups. We conclude that RCSP is a simple, safe, and effective means of cardioplegic protection during aortic valve surgery.

Adult↗
PubMed1982

Effects of acebutolol on myocardial infarct extension: a randomized electrocardiographic, enzymatic and angiographic study.

The effect of acebutolol (1 mg/kg i.v. during the first 2 days followed by a daily oral dose of 600 mg for 3 weeks) was studied in a randomized trial involving 26 patients seen within 24 hours after the onset of uncomplicated anterior transmural myocardial infarction (TMI). Myocardial ischemia and necrosis were evaluated by precordial maps recorded daily for 9 days. Left ventricular pump function and dyssynergy were quantitatively measured on 30 degrees right anterior oblique cineangiograms. Angiography was performed, using the postextrasystolic potentiation technique, within the first 24 hours after TMI and was repeated 1 month later. The basal and postextrasystolic beats from the initial angiography were computerized and compared with those from the final angiogram. MB-CK serum level was measured from blood samples drawn every 3 hours for the first 72 hours. Fourteen patients selected at random received acebutolol within the first 24 hours; 12 subjects were untreated and served as controls. During the 1-month study, no other drugs were administered. Treated patients showed a significant reduction in capillary wedge pressure, extent of hypokinesis and ST-segment elevation; no significant differences were observed in the control group. However, the predictability based on the angiographic data was the same in both groups, and beta blockade did not alter this predictability significantly. Furthermore, no significant difference was found during the final evaluation for treated compared with control patients for any single variable or set of variables. The incidence of infarct extension was not decreased, but only significantly delayed in treated patients. The high variability of the measurements, probably related to the high variability of the pathophysiologic factors, may account for the failure to demonstrate the efficacy of acebutolol.

Acebutolol↗
PubMed1982

[Effect of nitroglycerin and N-ethoxycarbonyl-3-morpholinosydnonomine on the walls of large arteries].

Systemic arterial compliance was measured in 20 patients with left ventricular failure due to congestive cardiomyopathy. The method consisted in evaluating arterial compliance by analysing the exponential fall of the arterial pressure curve on a simple visco-elastic model. In the patient group, significant correlations were found between arterial compliance and age (r = 0,64 ; p less than 0,01) and arterial compliance and systolic blood pressure (r = -0,58 ; p less than 0,001). These relationships suggest that arterial compliance depends on the height of the systolic blood pressure and/or the elasticity of the arterial walls. Two groups of patients were defined : Group I (10 patients) given a single oral dose of 7,5 mg of nitroglycerine (Lenitral), and Group II (10 patients) giben a single oral dose of 4 mg N ethoxycarbonyl-3-morpholinosydnonomine (Molsidomine). There was no significant difference in the hemodynamic parameters or arterial compliance between the two groups before administration of these drugs. However, systolic blood pressure was significantly lower (p less than 0,01) and compliance significantly higher (p less than 0,05) after treatment in Group II. In Group I, nitroglycerine caused a significant increase in compliance (p less than 0,01), a significant decrease in systolic (p less than 0,02) and mean blood pressure (p less than 0,05) whilst heart rate, cardiac output and total systemic resistance remained unchanged. In Group II, Molsidomine caused a significant increase in arterial compliance (p less than 0,01), a decrease in systolic (p less than 0,001), diastolic (p less than 0,01) and mean blood pressure (p less than 0,01) and in cardiac output (p less than 0,01), whilst heart rate and total systemic resistance remained unchanged. This study shows that both drugs studied had significant effects on the walls of the large arteries.

Adult↗
PubMed1981

Detection of residual myocardial function in acute transmural infarction using postextrasystolic potentiation. A computerized angiographic study.

Twelve subjects without clinical or hemodynamic heart failure, admitted for a first untreated anterior transmural myocardial infarction, were evaluated within the first 24 hours after the onset of symptoms. Pulmonary angiography was performed while a right ventricular extrastimulus was delivered every fourth beat at 50% of the RR interval to systematically analyze the basal and the postextrasystolic left ventricular frames. Left ventriculograms were quantitatively processed to determine the ejection fraction (EF) and the percentage of the end-diastolic circumference showing hypokinetic (%HK) or akinetic (%AK) areas. Left ventricular angiography was performed 1 month later in all cases at the same paced atrial heart rate to compare this final angiogram to the basal and the electrically induced postextrasystolic initial beats. During the 1-month period of the study none of these subjects had complications such as recurrent chest pain, heart failure or rhythm disturbances, and no drug administration was necessary. Comparing the basal cycle of the initial angiogram and the final cycle, a poor correlation was found between the corresponding values of EF (r = 0.34), %HK (r = 0.38) and %AK (r = 0.48). The correlations were much better when a comparison was made between the postextrasystolic cycle of the initial angiogram and the final cycle (EF, r = 0.84; %HK, r = 0.96; %AK, r = 0.95). These results indicate that, from the first day after a TMI, the analysis of the postextrasystolic frame allows accurate estimation of the final left ventricular function and regional wall motion abnormalities. Postextrasystolic potentiation may be useful in the acute state of transmural infarction to discriminate potentially reversible ischemic from definitely jeopardized areas.

Acute Disease↗
PubMed1981

Myocardial hypertrophy, rate of change of free wall thickness and directional components of ventricular power in man.

The diastolic (Vd) and systolic volumes, the average free wall diastolic thickness (hd) and left cardiac cavity pressures were determined in 25 subjects using monoplan angiography. Ten subjects presented a normal angiogram (NA), 5 a myocardiopathy with predominant dilatation (MCD), 4 a myocardiopathy with predominant non obstructive hypertrophy (MCH), and 6 a volume overload (VO). All the subjects had a normal coronary-cineangiogram. Myocardial volume (Vw) and systolic thickness were calculated from hd and from end-diastolic and end-systolic internal dimensions. The degree of myocardial hypertrophy was estimated from the value of Vw/Vd. The directional components of the total systolic elemental power due to thickening (average radial power : Pr) and to midwall circumferential shortening (average equatorial power : Pe) were calculated for each subject. Patients with NA, with MCD and with VO presented a positive linear correlation between Pr/Pe and Vw/Vd (r = 0.90). Patients with MCH were clearly below the regression line defined by the other groups. This relationship suggests that the contribution to the total power due to the thickening component is greater with increasing cardiac hypertrophy, except in the case of subjects showing an "inappropriate" hypertrophy.

Adult↗
PubMed1981

Closed-chest myocardial ischaemia in dog.

Myocardial ischaemia in dog was induced with releasable material in the distal segment of the anterior descending branch of the left coronary artery. Three releasable materials were tested: gel foam, wax microspheres (120-200 micron) and latex balloons, using different methods of introduction. The left carotid route was selected for introduction of a preformed catheter. The gel foam and wax microspheres caused transitory ischaemia, which was proximal for the foam and distal for the microspheres. The balloons made it possible to standardize the ischaemia as its localization and duration could be selected. This material therefore provided a model for stable chronic ischaemia. Nine dogs were observed by means of precordial mapping (36 electrodes) during the phase following ischaemia or for a period of 4 weeks. The results of these experiments are analysed and correlated with histological results for the post-mortem phase.

Animals↗
PubMed1978

[A simplified arteriographic analysis of systolic pressure and of the pressure-time index].

Systolic stress has been measured in 20 ms periods during ventricular ejection by monoplanar angiographic method, both under basal conditions and after infusion of trinitro-glycerine (TNG) in 8 coronary patients. None of them showed significant segmental contraction abnormality. No correlation was found between the corresponding values of mean systolic stress sigma and mean systolic pressure P, either under basal conditions (r=0.48) or after reduction of the load (r=0.24). On the other hand, values of sigma correlated closely with the corresponding values of the stress sigmas at the end of the isovolumic contraction phase, both under basal conditions (r=0.95) and after TNG (r=0.98. A similar correlation was found between the corresponding values of the peak of systolic stress and of sigmas both under basal conditions (r=0.94) and after TNG (r=0.96). Determination of sigmas is technically simple, and only requires the calculation of ventricular end-diastolic volume, together with measurement of end-diastolic thickness and aortic diastolic pressure. This simplified angiographic method is useful to express the determinants of myocardial energy using parietal stress values instead of intracavitary pressure values.

Angiography↗