Search PubMed⌕ Search

Biomedical subjects

L Guize

Publications and source records attributed to L Guize.

At least 73 records · Page 4Linked to original sources
PubMed1986

[Experimental induction of sino-auricular blocks on isolated atria. Microelectrode study of the effects of bepridil].

The effects of bepridil on sinoatrial conduction were studied by perfusing 15 isolate rabbit right atrial preparations. In a preliminary series an increase in cycle length was observed with a dose-dependent effect with concentrations of between 5 X 10(-7) M and 1 X 10(-5) M. At the latter dose, sinoatrial block was observed. Bepridil was therefore used in a series of 10 preparations to induce sinoatrial block (SAB). After 10 minutes perfusion the cycle length increased significantly (14.3%, p less than 0.02). In 4 preparations SAB occurred 18.7 +/- 2.5 minutes after the onset of the perfusion. Sinoatrial block did not occur in 6 cases and in 4 cases an intrasinus shift of the dominant pacemaker was observed. The types of SAB observed were varied and their mechanisms were complex. Different types of SAB occurred in the same preparation. The different types of block recorded were: Blumberger type I SAB, anterograde 2/1 SAB, intrasinus 2/1 block, retrograde 2/1 and advanced block, complete atrio-sinusal dissociation.

Action Potentials↗
PubMed1985

Is the relationship between blood pressure and cardiovascular risk dependent on body mass index?

The relationship between blood pressure and cardiovascular mortality according to body mass index has been analyzed in two French prospective studies: the Paris Prospective Study, composed of 7,704 men aged 40-53 years examined in 1967-1972, and the Investigations Pré-Cliniques Study, made up of 19,618 men aged 40-69 years who underwent a checkup in 1970-1980. In the Paris Prospective Study, during a mean follow-up of 11.2 years, 241 cardiovascular deaths occurred, while in the Investigations Pré-Cliniques Study, with a mean follow-up of 7.6 years, 262 cardiovascular deaths occurred. A Cox survival analysis was performed on the data of each study to test the interaction of blood pressure and body mass index in the prediction of cardiovascular risk. Both analyses demonstrate a significant negative interaction, suggesting that a decreasing trend of the relative risk of cardiovascular death with increasing body mass index is better supported by the data than a constant relative risk. These results might have some bearing on the problem of the management of hypertension in overweight subjects.

Adult↗
PubMed1985

[Clinical and electrophysiological aspects of median intra-His bundle block with normal electrocardiogram at rest].

The clinical and electrophysiological features and the natural history of median intra-His block with a normal resting electrocardiogram were studied: 11 patients had a fixed split H1-H2 potential with a spontaneous or induced block between H1 and H2. The patients (5 men and 6 women) were aged 17 to 70 years (average 53 years). Associated pathology included 2 cases of aortic stenosis (1 severe), 1 case of ischaemic heart disease (effort angina), 1 case of mitral valve prolapse and 2 cases of hypertension. The presenting symptoms were syncope (4 cases), dizziness (2 cases), effort angina (1 case) and tiredness (3 cases); 1 patient was asymptomatic. Holter monitoring (24 hours) was performed in 8 patients and s-owed paroxysmal conduction defects in 6 cases; 4 Mobitz II 2nd degree AV block, 1 3rd degree AV block with narrow QRS complexes and 1 case of blocked atrial extrasystoles at coupling intervals longer than 480 ms and sinus cycle lengths of over 800 ms. Exercise testing by bicycle ergometry (4 patients) was normal in 1 case and revealed Mobitz II 2nd degree AV block in 3 cases. Baseline electrophysiological studies showed an A-H1 interval ranging from 60 to 100 ms (average 78 ms), a H1-H2 interval of 20 to 40 ms (average 31 ms) and a H2-V interval of 30 to 50 ms (average 32 ms). Block between H1 and H2 was observed: "spontaneously" during electrophysiological investigation in 6 cases, after IV atropine in 1 case, during overdrive atrial pacing at rates slower than 150/min in 7 cases, after atrial extrastimulus with a functional intra-His refractory period of over 420 ms in 7 cases, after ajmaline in 3 of the 4 cases in which this test was performed. A cardiac pacemaker was implanted in 10 patients in whom the initial symptoms have all regressed; the remaining patient considered to be "epileptic" had another syncopal attack under therapy and was finally paced. This series demonstrates that the diagnosis of median intra-His block depends on precise electrophysiological criteria and should be looked for even when the presenting symptoms are atypical; some of our patients complained only of tiredness. The value of Holter monitoring and careful endocavitary investigation is emphasised. Median intra-His block should be distinguished from longitudinal and functional His bundle dissociation.

Adolescent↗
PubMed1985

[Prevalence and course of Wolf-Parkinson-White syndrome in a population of 138,048 subjects].

The prevalence of the Wolff-Parkinson-White (WPW) syndrome, frequency of arrhythmias and their evolution were studied in a group of volunteers consisting in 79,978 men and 59,070 women, aged from 20 to over 70. The higher prevalence of WPW in men than in women (p less than 0.001) decreased significantly with age, much more in men (p less than 0.001) than in women (p less than 0.05). Ventricular pre-excitation was intermittent in 6.7 p. 100 of men and in 16 p. 100 of women. The probable site of pre-excitation, determined on the orientation of the delta wave was more often left than right (104 vs 66, p less than 0.02). The frequency of paroxysmal tachycardia increased with age: 10 p. 100 of the cases from 20 to 39 years of age, 29 p. 100 from 40 to 59, 36 p. 100 at 60 and over (p = 0.05). It was 1.7 times more frequent in cases of left pre-excitation. A hundred and fifty-one patients were followed-up from 1 to 11 years (4.6): 5 patients died, 3 of non-cardiac and 2 of undetermined causes, with one sudden death in a 29 year old man. Fifty-three patients were reviewed 4.5 years after the initial examination: 9 pre-excitations (7 right, 2 left) had disappeared. In conclusion, the higher prevalence of WPW in men decreases with age. This decrease appears to be essentially due to the disappearance of the ventricular pre-excitation and not to an increased mortality. Arrhythmias are more frequent in older patients with left-sided pre-excitation.

Adult↗
PubMed1984

[Biological profile in acute coronary insufficiency: study of blood myoglobin, enzymes and inflammatory proteins].

17 patients admitted to an intensive coronary care unit for premonitory syndrome or acute myocardial infarction were divided into four groups (premonitory syndrome, non-transmural infarction, transmural infarction with and without inflammation) on the basis of electrocardiographic findings and total CK activity. Serum levels of CK and CK2, myoglobin, ASAT and ALAT, LDH, haptoglobin, CRP and alpha-1 acid glycoprotein were determined daily for ten days. Patients with premonitory syndrome had no significant increase in markers of cytolysis or myoglobin. In acute myocardial infarction, regardless of clinical type, time course of peak values for biologic factors assayed was as follows: D0: myoglobin; D1: CK and CK2; D0 to D2: ASAT; D2 to D5: LDH and CRP; D5 to D6: ALAT; D4 to D7: haptoglobin and alpha-1 acid glycoprotein. These parameters may increase with size of myocardial necrosis and association with an inflammatory syndrome (CK, LDH, CRP and alpha-1 acid glycoprotein). They may be predictive of poor prognosis (LDH at peak CK concentrations). Some determinations, both more difficult to perform and less specific, have a particular value: prompt diagnosis of myocardial necrosis and detection of early repeat infarction by myoglobin assay, retrospective diagnosis by inflammatory protein assays when total CK has returned to normal.

Angina, Unstable↗
PubMed1984

[Measured and estimated sinoatrial conduction during variations in rhythm. Microelectrode study of the isolated rabbit atrium].

Strips of isolated atrium were obtained from 10 rabbits to study the validity of indirect methods of estimating sinoatrial conduction time during variations of the sinus rhythm. Direct recordings of the trans-membrane action potential of the sinus node were made. Mapping of the sinus region was undertaken to determine the site of the dominant pacemaker. A quadripolar surface electrode was positioned on the lower part of the crista terminalis for stimulation and recording of the atrial potential. This enabled a comparison to be made between the indirect estimated and the directly measured conduction times. An intrasinusal shift of the dominant pacemaker was obtained by cooling from 38 degrees C to 35 degrees C. This shift occurs progressively in the cranino-candal direction. The estimated and measured conduction times were compared under basal conditions and after cooling. The sinus cycle was significantly longer (p less than 0.001) at 35 degrees C (318 +/- 68 ms) than at 38 degrees C (255 +/- 48 ms). The mean measured anterograde conduction time also decreased from 36 to 31 ms (p less than 0.01) and the mean measured retrograde conduction time also decreased from 39 to 33 ms (p less than 0.02); the total conduction time decreased from 75 to 64 ms (p less than 0.001). The results of the total estimated conduction times were discordant. The associated effects of stimulation and cooling can cause conduction defects and an overestimation of the conduction time.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1984

[Magnesium deficiencies in cardiovascular diseases].

Plasma (pl), red blood cell (ery) and urinary magnesium (Mg) concentrations were measured by spectrophotometry in over 300 patients at the Cardiology Department of Broussais Hospital. Other biological parameters, including pl and ery potassium, calcium and phosphate concentrations were measured simultaneously. In a control group (54 subjects) the mean pl Mg was 0,851 mmol/l in men and 0,819 mmol/l in women; mean ery Mg was 2,12 mmol/l and 2,09 mmol/l respectively. Magnesium depletion was observed in several pathological cardiovascular conditions: -- mitral valve prolapse: the Mg levels were significantly lower in women (19 cases) (pl Mg 0,740 mmol/l; ery Mg 1,83 mmol/l: p less than 0,001); the deficit was less pronounced in men: pl Mg 0,829 mmol/l, p less than 0,01, and ery Mg 2,01 mmol/l (NS); -- recurrent junctional tachycardia (21 cases): the Mg levels were significantly lower than normal: pl Mg = 0,796 mmol/l in men and 0,763 mmol/l in women; ery Mg = 1,93 and 1,88 mmol/l, respectively; -- coronary insufficiency (86 cases): pl Mg = 0,821 mmol/l in men and 0,768 mmol/l in women (p less than 0,001). In a subgroup with coronary spasm (22 cases), the mean ery Mg was decreased (2,01 mmol/l, p less than 0,05); -- unstable or labile hypertension (24 cases): the decrease was significant, especially in women (pl Mg = 0,796 mmol/l, ery Mg = 1,88 mmol/l). These magnesium deficits were sometimes associated with a low pl Ca, and often associated with a low ery K although pl K was usually raised. In some privileged cases of cardiac arrhythmia and coronary spasm, intravenous Mg repletion was beneficial but did not affect plasma concentrations. The role of magnesium depletion in cardiovascular disease remains obscure and requires further study.

Adolescent↗
PubMed1984

[A large aneurysm of the inferior mesenteric artery. Apropos of a case. Review of the literature].

The prevalence of inferior mesenteric aneurysms is difficult to evaluate in the literature, only four cases having been published up to the present. The case described here was a large aneurysm of the inferior mesenteric artery measuring 10 cm by 8 cm of atheromatous origin, discovered echotomographic investigation of an abdominal mass and confirmed by aortography. Operation consisted in endoaneurysmorrhaphy with reimplantation of the main branch supplying the sigmoid arteries into the aorta combined with reimplantation of the right common iliac eroded by the aneurysm into the right side of the aorta. This type of lesion raises two problems: diagnostic: echotomography and digitalised angiography will certainly facilitate the detection of such lesions, the risk of rupture of which is considerable; therapeutic: distal reimplantation of the inferior mesenteric artery which is decided on the basis of its anatomical state and above all the superior mesenteric and coeliac collateral circulation in order to avoid any risk of ischaemia of the descending colon.

Aneurysm↗
PubMed1983

[Comparison of various indirect methods for evaluation of sinus function].

Sinus node function was evaluated by Mandel, Strauss and Narula's methods in 60 consecutive patients: 20 females, 40 males; average age 59 +/- 17 years. Three had second degree sinoatrial block, 2 had bradycardia-tachycardia syndromes and 10 had sinus bradycardia. The corrected sinus node recovery time was 414 +/- 417 ms. It exceeded 520 ms in 8 cases, 5 where the two other methods confirmed sinus node dysfunction, 1 where the two other methods showed no abnormality. In the last two patients pathological results with Narula's method coincided with normal values with Strauss' method but the basal sinus cycle and the post return cycle differed from one method to the other. The atriosinoatrial conduction time estimated by Narula's method was 274 +/- 117 ms. In the thirteen cases where it exceeded 300 ms abnormal results were also recorded with Strauss' (11 cases) and/or Mandel's method (7 cases). The atriosinoatrial conduction time assessed by Strauss' method was 239 +/- 106 ms. It exceeded 300 ms in 18 patients. In these patients the results of Narula and Mandel's methods were normal in 7 cases. This discordance cannot be explained either by variations in the catheter position, or by the duration of the basal sinus or the post return cycles. This raises the question of penetration of the sinus node by the last stimulus when Narula's technique is used. A significant linear correlation was observed between the atriosinoatrial conduction time assessed by Narula's method and the atriosinoatrial time assessed by Strauss' method (N = 60; r = 0,59) and with the corrected sinus node recovery time (N = 60; r = 0,43) and a double linear correlation was found with these two parameters (N = 60; r = 0,62). There was no significant linear correlation between the atriosinoatrial conduction time assessed by Strauss' method and the corrected sinus node recovery time (N = 60; r = 0,27). The atriosinoatrial conduction time evaluated by Narula's method seems to be intermediary between the two other parameters which seem to be independent of each other.

Adolescent↗
PubMed1983

[Conduction disorders and aneurysms of the sinus of Valsalva].

A series of 15 sinus of Valsalva aneurysms (SVA) admitted between 1961 and 1981 was reviewed to analyse associated conduction defects. It comprised 11 men and 4 women; the mean age was 31 years (range 16 to 53). The diagnosis of SVA was made at the time of rupture (4 cases), during investigation of associated cardiac disease (8 cases), at surgery (1 case) and during advanced conduction disorders (2 cases). All patients underwent catheterisation and angiography. Endocavitary electrophysiological studies were performed in 3 patients. Eight out of 15 patients had conduction defects which comprised: incomplete right bundle branch block (2 cases), atrioventricular block (AVB) (6 cases). Endocavitary investigation of 3 of the 6 AVB showed conduction defects at several levels: sino atrial, suprahisien, intrahisian and infrahisian blocks (1 case); transient complete AVB with 1 degree and 2 degree intrahisian block (1 case); complete AVB, six years after correction of SVA, due to infrahisian block (1 case). Thirteen of the 15 patients underwent surgery; none of the 9 cases of SVA without conduction defects before surgery developed conduction defects. Four of the 6 cases of AVB required permanent pacing; there was 1 postoperative death. One patient was not operated. These conduction defects were caused by the close relationship of the SVA to the intracardiac conduction pathways. The right anterior was the most commonly affected sinus. The investigation of AV conduction should be systematic in cases of SVA, and, conversely, the finding of AVB in young patients should alert the physician to the possibility of a SVA.

Adolescent↗
PubMed1983

[Dissection of the ascending aorta after aortic valve replacement].

Three patients who underwent aortic valve replacement had dissection of the ascending aorta 7 months, 2 years and 15 years after surgery. This is a rare complication of aortic valve replacement (11 reported cases). Its incidence estimated from the literature would appear to be less than 1% of all aortic valve replacements. It occurs in both cases of stenosis and regurgitation (4 aortic regurgitations, 2 aortic stenosis, 5 mixed aortic valve disease) and is seen in ball and cage (7 cases), tilting disc (3 cases) and bioprosthesis (1 case). Six of these patients had hypertension. The role of the initial surgery for valve replacement in secondary aortic dissection is discussed. Aortic clamping and cannulation can cause immediate dissection but may also damage the aortic wall, leading to the risk of secondary dissection. An aneurysm of the ascending aorta was observed in 5 Cases at surgery; in 3 cases, the aorta was dilated without true aneurysm; in 3 other cases the aorta was considered to be macroscopically normal. The integrity aorta is sometimes difficult to confirm and a macroscopically normal of the aorta may have fragile aortic walls, especially in cases of aortic regurgitation due to valvular dysplasia and forms frustres of Marfan's syndrome, and are associated with a risk of secondary dissection. The appearances of the aorta at aortic valve replacement influence the choice of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

[Supraventricular tachycardias induced by swallowing].

The authors report the case of a 34 year old woman admitted to hospital for attacks of atrial tachycardia inducing very poorly tolerated junctional tachycardia at 260 beats/min. The attacks were always induced by swallowing and could be reproduced at will. Electrophysiological studies could only be undertaken after the administration of large doses of amiodarone. An exclusively retrograde rapidly conducting paranodal accessory pathway was demonstrated with triggering of runs of reentrant tachycardia. No underlying gastro-oesophageal or cardiac disease apart from thromboembolism was found. Swallowing-induced supraventricular tachycardia is rare and possible mechanisms are discussed. The arrhythmia may be triggered by direct mechanical stimulation, by changes in vagosympathetic tone, or by an association of the two phenomena. Previously published reports describe similar clinical situations resulting from a variety of different mechanisms.

Adult↗
PubMed1982

Intra-SA-nodal pacemaker shift: indirect evaluation in the open chest dog.

Thirteen open chest dogs with normal sinus node function were studied by premature stimulations with a constant relative prematurity--50% of the preceding sinus cycle length. These premature beats were induced in the lower part of the crista terminalis of the right atrium and to the roof of the left atrium. Significant linear correlations were found between the return cycle (A2A3) and the spontaneous cycle (A1A1) lengths, with a slope of +0.75 in the right atrium, +1.36 in the left atrium. The evaluation of sinus node function is disturbed by pacemaker shifts, both spontaneous and induced. Sinus node organisation may be assessed by stimulating standardised sites, by measuring intra-atrial conduction time, and by comparing A2A3 with A1A1 at constant relative prematurity during significant variations in A1A1 obtained with changes in vago-sympathetic tone.

Animals↗
PubMed1982

[Prevalence and electrocardiographic forms of the Wolff-Parkinson-White syndrome].

In a routine electrocardiographic study of 133929 subjects aged from 20 to 73, 136 cases of the Wolff-Parkinson-White syndrome were detected, 6 with intermittent pre-excitation. In this study, the prevelance of WPW was about 1 in a 1000, the highest incidence being in the 20-40 year age group with an equal sex ratio. The ECG analysis of the 136 cases consisted in determining the orientation of the delta wave in the precordial leads to establish the right or left ventricular origin of the pre-excitation, calculating the direction of the delta wave vector in the frontal plane to find out the anterior, lateral or posterior origin of the pre-excitation and analyse the position of the QRS axis to assess the appearances of the latest ventricular activity. The 136 ECGs were then classified according to electrophysiological criteria and the results of mapping: 1. Left ventricular pre-excitation; 74 cases characterised by a dominant delta wave in the right precordial leads. These cases were subdivided into: - 30 cases with posterior paraseptal pre-excitation, axis of the delta wave deviated superiorly and to the left, between -30 degrees and -60 degrees; - 20 cases of lateral pre-excitation with the vector of the delta wave deviated inferiorly and to the right between +100 degrees and +120 degrees; - 24 cases of anterior paraseptal pre-excitation with high amplitude delta and QRS deflections in all precordial leads and a delta wave axis between +50 degrees and +80 degrees. 2. Right ventricular pre-excitation; 62 cases characterised by a negative or isoelectric delta wave in the right precordial leads, including: - 14 posterior paraseptal pre-excitation with significant delta wave axis deviation between -30 degrees and -60 degrees; - 33 lateral pre-excitation with the delta and QRS axis pointing directly to the left at about 0 degrees; - 15 cases of anterior paraseptal pre-excitation with the delta wave axis between +50 degrees and +80 degrees. The cases with terminal forces of left ventricular activation in the same direction as the delta wave, superiorly and to the left at -60 degrees or inferiorly and to the right at +120 degrees, forming a single deflection of over 0,12 seconds' duration, are the result of delayed activation of the anterior or posterior fascicle of the left bundle after a long delay. On the other hand, the cases in which the direction of the pre-excitation is the same but the final part of ventricular activation moves away from the delta are probably the result of tension between the activation of the normal and accessory pathways.

Adult↗