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Biomedical subjects

M Gueron

Publications and source records attributed to M Gueron.

At least 19 recordsLinked to original sources
PubMed2001

Left anterior descending artery length in left and right coronary artery dominance.

BACKGROUND: Coronary stenosis of the left anterior descending artery (LAD) is respected by cardiologists because of its negative influence on morbidity and mortality. An important anatomical consideration is the length of the LAD. OBJECTIVE: To investigate the relationship between length of LAD and coronary dominance. DESIGN: Retrospective comparison of 100 consecutive angiograms with left coronary dominance with 100 consecutive angiograms with right coronary dominance. The relationship between the length of the LAD and coronary dominance was analyzed. METHODS: We retrospectively compared 100 consecutive angiograms with left coronary dominance (the posterior descending artery being supplied by the circumflex artery) with 100 consecutive angiograms with right coronary dominance (the posterior descending artery being supplied by the right coronary artery). LADs were categorized into three types: type A, LAD terminating before the cardiac apex; type B, LAD reaching the apex but not supplying the inferoapical segment of the left ventricle; and type C, LAD wrapping around the apex and supplying the inferoapical segment. LAD typing was also analyzed in relation to gender. RESULTS: It was found that the LAD wrapped around the apex in 87% of cases of left coronary dominance but only in 47% of patients with right coronary dominance, and that the long LADs were more frequently seen in women than in men, irrespective of coronary dominance. CONCLUSIONS: We found that the LAD in left coronary dominance is usually long and wraps around the apex, and believe that angiographic interventions in such cases have important clinical significance.

Coronary Angiography↗
PubMed2000

Arthropod poisons and the cardiovascular system.

Animal poisons induce myocardial damage after envenomation. The cardiac manifestations after black widow spider bite are rarely observed and their prognostic significance are not known. Hymenoptera induce anaphylactic manifestations commonly observed in adults with previous coronary artery disease although myocardial involvement is observed in a few without previous heart disease. The mechanism of cardiac involvement after scorpion envenomation has been elucidated, however after widow spider bite or hymenoptera stings the mechanism of myocardial damage of those without previous heart disease is not clear.

Adult↗
PubMed1998

Coronary collaterals in patients with normal and impaired left ventricular systolic function.

One hundred and twenty consecutive patients with significant coronary artery disease, normal left ventricular systolic function and coronary collaterals (group A) were compared to 120 patients with the same characteristics but with left ventricular systolic dysfunction (group B). No significant differences were found between the two groups on age, hypertension, diabetes mellitus and smoking. The left ventricular end diastolic pressure was 16+/-7 in group A, and 24+/-9 in group B (P<0.01). The number of diseased vessels was similar in both groups. More completely occluded vessels were found in group B (155 vs. 101 in group A). No significant difference was detected between the two groups in the distribution of the diseased vessels. In both groups, the richest collateral supply was to the right coronary artery, followed by collaterals to the left anterior descending. The poorest supply was to the left circumflex. In conclusion, patients with normal and abnormal left ventricular systolic function have similar coronary collateral characteristics.

Aged↗
PubMed1998

Exaggerated blood pressure response at exercise in normotensive subjects: demographic and stress performance characteristics.

BACKGROUND: Exercise testing is an important diagnostic and prognostic procedure in the assessment of patients with hypertension. An exaggerated blood pressure response to exercise among normotensive subjects was found to be one of the best predictors of future hypertension. The demographic characteristics of patients with an exaggerated blood pressure response during exercise have not been adequately described. METHODS AND RESULTS: The demographic and stress performance characteristics of 2 groups of normotensive patients referred for exercise testing, one composed of patients with an exaggerated blood pressure response (group I, n=146) and a group of patients with a normal blood pressure response (group II, n=439) were prospectively compared. Patients in group I were older than those in group II (54+/-12 vs 51+/-13 years, P < .05). More men than women were found in both groups, yet significantly more in group I than in group II (83% vs 69% P < .001). Significantly more among the patients in group I had a higher level of education and were of Western origin than those in group II (P < .01). The resting systolic and diastolic blood pressures were higher in group I than in group II (131+/-18 vs 119+/-14 mm Hg, P< .001, and 81+/-8 vs 76+/-7 mm Hg, P < .001, respectively). The patients in group I achieved a higher percentage of the maximal predicted heart rate (88+/-7 vs 85+/-9 beats/min, P < .01). No significant differences were found between the groups in the duration of stress test and effort ischemia. CONCLUSIONS: Patients with a hypertensive blood pressure response during stress testing have specific demographic and exercise characteristics.

Adult↗
PubMed1998

Patients with coronary collaterals and normal left ventricular systolic function: clinical, hemodynamic, and angiographic characteristics.

One hundred and twenty consecutive patients with significant coronary artery disease, normal left ventricular systolic function, and coronary collaterals were compared with 111 patients with the same characteristics but with no collaterals. No significant differences were found between the two groups in hypertension, diabetes mellitus, and smoking. The left ventricular end diastolic pressure was 16.4+/-7 in the study group and 16.9+/-6.9 in the controls (NS). Significantly more diseased vessels were observed in the study group than in the control group (2.1+/-0.6 versus 1.7+/-0.6, p=<0.001). One hundred and one totally occluded vessels were found in the study group but only two in the control group. The richest collateral supply was to the right coronary artery: 94 sources to 85 diseased vessels (111%) including 66 sources to 52 totally occluded arteries (127%); to the left anterior descending: 59 sources to 89 diseased vessels (66%) including 37 sources to 33 totally occluded arteries (112%). The poorest supply was to the left circumflex: 17 sources to 69 diseased vessels (25%), including nine sources to 16 totally occluded arteries (56%). No collaterals were observed in 14 totally occluded vessels in the study group and in two of the controls, while the systolic function at rest was still normal. It is suggested that coronary collaterals are important in preserving left ventricular systolic and diastolic performance at least at rest. Not readily visible collaterals may also prevent systolic dysfunction.

Case-Control Studies↗
PubMed1997

[Angina pectoris and the severity of coronary artery stenosis].

The relationship between angina pectoris and the severity of coronary artery disease was evaluated in 146 patients with normal segmental and global, left ventricular, systolic performance. None had unstable angina or a previous myocardial infarction. A strong relationship was found between angina and the severity of coronary artery disease (p < 0.005). Significant, stable, angina pectoris as a clinical symptom indicated advanced coronary artery disease in this selected group of patients.

Angina Pectoris↗
PubMed1996

Acid-induced exchange of the imino proton in G.C pairs.

Acid-induced catalysis of imino proton exchange in G.C pairs of DNA duplexes is surprisingly fast, being nearly as fast as for the isolated nucleoside, despite base-pair dissociation constants in the range of 10(-5) at neutral or basic pH. It is also observed in terminal G.C pairs of duplexes and in base pairs of drug-DNA complexes. We have measured imino proton exchange in deoxyguanosine and in the duplex (ATATAGATCTATAT) as a function of pH. We show that acid-induced exchange can be assigned to proton transfer from N7-protonated guanosine to cytidine in the open state of the pair. This is faster than transfer from neutral guanosine (the process of intrinsic catalysis previously characterized at neutral ph) due to the lower imino proton pK of the protonated form, 7.2 instead of 9.4. Other interpretations are excluded by a study of exchange catalysis by formiate and cytidine as exchange catalysts. The cross-over pH between the regimes of pH-independent and acid-induced exchange rates is more basic in the case of base pairs than in the mononucleoside, suggestive of an increase by one to two decades in the dissociation constant of the base pair upon N7 protonation of G. Acid-induced catalysis is much weaker in A.T base pairs, as expected in view of the low pK for protonation of thymidine.

Base Sequence↗
PubMed1996

Interleukin-6 release following scorpion sting in children.

Interleukin-6 levels were measured in the serum of ten children following severe scorpion envenomation. Measurements were taken on arrival, at the emergency room, and 12 and 24 hr after arrival. Interleukin-6 was markedly elevated in the serum of eight out of ten children on arrival. Interleukin-6 levels gradually decreased toward normal values on 12 and 24 hr measurements, but remained above control levels on all measurements. These results imply that signs and symptoms following scorpion envenomation may in part be explained by release of cytokines. Human and experimental animal studies are required in order to verify the assumption that interleukin-6 and other cytokines are involved in the pathogenesis of scorpion envenomation.

Animals↗
PubMed1995

Relation between shortness of breath, left ventricular end diastolic pressure and severity of coronary artery disease.

The relation of shortness of breath to left ventricular end diastolic pressure and the severity of coronary artery disease was evaluated in 146 patients with normal segmental and global left ventricular systolic performance. None had chronic lung disease, cardiomyopathy, previous myocardial infarction, uncontrolled hypertension or unstable angina pectoris. A strong relationship was found between shortness of breath and elevated left ventricular end diastolic pressure, and a borderline relationship with the severity of coronary disease. Shortness of breath as a clinical symptom indicates diastolic dysfunction in this selected group of patients.

Adult↗
PubMed1995

Angiographic follow-up of coronary artery ectasia.

Of 1,125 patients catheterized over a period of 8 years, 68 (6%) had coronary ectasia. Twenty-five of them were catheterized at least twice and constituted the study group. The time between the first and last catheterization ranged from 2 to 8 years (mean +/- SD = 4.2 +/- 1.6). Coronary ectasia was more frequent in males (88%). The frequency of involvement was: the right coronary (47%), the left circumflex (30%), the left anterior descending (21%) and the left main arteries (2%). Proximal segments were most frequently involved (48%). Diffuse involvement was found in 29%. Severity of ectasia progressed in 6 segments (14%) and 2 new ectatic segments appeared over the follow-up period. During that period, 2 patients had myocardial infarction, 1 of them due to a total occlusion of an ectatic segment. There were no deaths. In conclusion, coronary ectasia has a relatively benign course.

Adult↗
PubMed1994

Abnormal coronary perfusion in experimental scorpion envenomation.

Perfusion defects and left ventricular dilation after experimental scorpion envenomation were evaluated in five dogs. Left Left ventricular dilation was observed in three dogs and right ventricular dilation in one other, in scans immediately after envenomation. Perfusion defects were inferred from scans in four dogs. The data are strongly suggestive of coronary hypoperfusion, and the mechanics of abnormal coronary flow after scorpion envenomation are discussed.

Animals↗
PubMed1994

The role of the intensivist in the treatment of the cardiovascular manifestations of scorpion envenomation.

The following report summarizes the role of the intensivist in the treatment of the cardiovascular manifestations of scorpion envenomation within the intensive care unit. It emphasizes the need for a clear understanding the mechanisms involved behind the manifestations of myocardial damage and the rational approach of aggressive treatment of the overstimulated autonomic nervous system. The report emphasizes the complexity of the clinical picture and the intensivist approach based on clinical and experimental evidence, with excellent results.

Animals↗
PubMed1994

Left ventricular performance in patients with normal coronary arteries: hemodynamic characteristics and clinical follow-up.

Of 111 patients with normal coronary angiograms, 68 patients had elevated left-ventricular end diastolic pressure and 'low-normal' ejection fraction (Group I) while the other 43 patients had normal left ventricular end diastolic pressure and 'high normal' ejection fractions (Group II). Although the number of patients was too small for meaningful statistical analysis, systematically a higher percentage of patients with diabetes mellitus, hypertension, hypercholesterolemia and smoking history was found in Group I. In contrast to the patients in Group II, patients in Group I tended to have more angina and ischemic events.

Blood Pressure↗
PubMed1994

Scorpion envenomation and antivenom therapy.

The clinical course and outcome of scorpion envenomation in 52 children treated in a pediatric intensive care unit without specific antivenom were retrospectively evaluated and compared with those of scorpion envenomation in the 52 preceding cases treated with specific scorpion antivenom. The demographic, clinical, and laboratory features on hospital arrival were similar in the two groups. The lengths of stay in the pediatric intensive care unit and in the pediatric wards were comparable. Hypotension with pulmonary edema developed in four of the children who did not receive antivenom and in one child who did receive antivenom as a complication of the envenomation; all completely recovered. Cardiogenic shock occurred in one child who did not receive antivenom, but who recovered completely, and in three children who received antivenom, of whom two died and one survived with a major deficit. Our study did not demonstrate any beneficial effect of therapy with antivenom for scorpion envenomation in children. However, our "control" group (i.e., the treated group) was a historical one; thus a prospective, randomized study appears to be warranted. Such a study may define specific subgroups that may benefit from treatment with antivenom.

Adolescent↗