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Biomedical subjects

R Bonan

Publications and source records attributed to R Bonan.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Effect of subvalvular disease on results of percutaneous mitral valvotomy].

In order to study the results of percutaneous mitral valvuloplasty (PMV), subvalvular mitral disease was classified using: 1) the transthoracic echo score (0-4), 2) an index derived from left ventricular angiography defined as the ratio of the distance from the extremity of the papillary muscle and the mitral valve in systole and the distance between the beginning of the aortic root and the apex of the left ventricle in diastole. This index of subvalvular fibrosis could be measured in 80 out of our first 103 PMV performed without complication; the mitral surface are a increased from 1.1 +/- 0.4 to 2.2 +/- 0.8 cm2 (p less than 0.0001). After PMV, mitral regurgitation was observed or was aggravated in 28 patients (35%), by one grade in 25 and by more than one grade in 3. The overall echo score was 8.3 +/- 1.5 and that of subvalvular fibrosis was 2 +/- 0.6. The angiographic index of subvalvular fibrosis was 0.18 +/- 0.04. No correlation was observed between echo and angiographic appreciation of subvalvular fibrosis. Multivariate analyses were selected: 1) the overall echocardiographic score (r = -0.45, p less than 0.0001), but not the angiographic index of subvalvular fibrosis or echocardiographic score of subvalvular fibrosis, was predictive of increase of valve surface area; 2) the absence of mitral regurgitation before PMV (p less than 0.01) and an angiographic index of subvalvular fibrosis less than or equal to 0.15 (p less than 0.03) were predictive of increased mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Immediate results and mid-term follow-up after percutaneous mitral valve replacement].

Percutaneous mitral valvuloplasty (PMV) was performed by the anterograde transseptal approach (double balloon technique) in 154 patients with symptomatic mitral stenosis. The mean age of the patients was high (53 +/- 14 years), 87% were women, 68% were in functional Classes III or IV of the NYHA and 37 (24%) had previously undergone surgical commissurotomy. The echocardiographic score was 8.5 +/- 1.6. PMV could not be completed because of a technical failure or a complication in 14 cases (9%). In the other patients, PMV increased mitral surface area from 1.0 +/- 0.3 to 2.0 +/- 0.8 cm2 (p less than 0.0001). A haemodynamic success (greater than or equal to 25% increase in mitral surface area and final area greater than or equal to 1.5 cm2) was obtained in 104 patients (75%). The predicting factors of success were echocardiographic score (8.1 +/- 1.4 versus 9.4 +/- 1.7; p less than 0.0001) and cardiac output (4.0 +/- 1.1 versus 3.0 +/- 1.0/l/min; p less than 0.0001). The duration of the procedure, the technical failure rate and the frequency of cardiac perforation were influenced by the learning curve. The degree of mitral regurgitation increased after PMV in 34% of cases, usually by one grade and without clinical or haemodynamic consequences. Acute mitral regurgitation was a rare (3%) and impredictable complication. An interatrial shunt was demonstrated in 80% of cases after PMV but the Qp/Qs ratio rarely exceeded 1.5 (11%). This shunt disappeared or decreased in the majority of cases during follow-up. The clinical result was an improvement of at least one functional Class in 83% of cases at 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Percutaneous mitral valvuloplasty. An analysis of the immediate results].

Percutaneous mitral valvuloplasty (PMV) was performed by the anterograde transseptal approach in 113 patients with symptomatic mitral stenosis. Mean age was 53 +/- 14 years and 89% were female. PMV resulted in a marked decrease in mitral gradient from 16 +/- 5 to 6 +/- 3 mmHg (p less than 0.0001) and a significant increase in mitral valve area from 1.09 +/- 0.36 to 2.12 +/- 0.83 cm2 (p less than 0.0001). An optimal hemodynamic result (gain in valve area greater than or equal to 25% and post-PMV valve area greater than or equal to 1.5 cm2) was obtained in 82 patients (73%). Multivariate statistical analysis selected as independent predictors of an optimal result: normal cardiac index (p = 0.0001), NYHA functional class less than 3 (p = 0.002), smaller left atrial diameter (p = 0.005), and echocardiographic score less than or equal to 8 (p = 0.01). The lowest frequency of optimal results was observed in patients with echocardiographic scores greater than or equal to 11 (20%). Three patients died (2.6%). All deaths occurred among the first 34 patients and none in the last 79 (p less than 0.05). Morbidity was also influenced by a learning curve effect. Mitral regurgitation developed or increased in severity in 38% of patients. This increase was mild (1 degree) in 85% of cases. Although the incidence of atrial shunting was high (76% by indicator dilution curve and 33% by oximetry), their magnitude was usually small (mean Qp/Qs 1.23 +/- 0.23) and lacked clinical significance. In conclusion, PMV provides excellent immediate hemodynamic results with low mortality and morbidity risks, specially once experience has been gained with this technique. Patients with echocardiographic scores less than or equal to 8 and smaller left atrial diameters, usually younger and less symptomatic, are the best candidates for PMV.

Adult↗
PubMed1990

Left-to-right atrial shunting after percutaneous mitral valvuloplasty. Incidence and long-term hemodynamic follow-up.

To assess the incidence and long-term evolution of left-to-right atrial shunting (AS) after the performance of percutaneous mitral valvuloplasty (PMV), venovenous indicator dilution curves and right heart oximetric measurements were obtained in 68 consecutive patients before and after successful PMV. The procedure increased the mitral valve area (p less than 0.0001) and decreased the mitral gradient (p less than 0.0001). No AS was detected before PMV, but it was detected immediately after PMV. Oximetry identified AS in 17 patients (25%), and dilution curves identified AS in an additional 25 (total, 62%). The ratio of mean pulmonary to systemic blood flow (Qp/Qs) was 1.31 +/- 0.2, and in six patients (9%), the ratio was 1.5 or greater. Among nine clinical, 20 hemodynamic, and six procedural variables, stepwise logistic regression analysis selected the following as independent predictors of AS: smaller increases in valve area (p = 0.01) after PMV, absence of previous surgical commissurotomy (p = 0.02), mitral valve calcification (p = 0.02), and smaller left atria (p = 0.06). Among the 33 patients recatheterized at 6 months, oximetry had detected AS in 10, and dilution curves detected AS in an additional nine (total, 58%) immediately after PMV. At 6 months, AS had decreased or disappeared in 14 of these patients (74%), had increased in three (16%), and was unchanged in two (10%). Overall, at 6 months, oximetry identified AS in three patients, and dilution curves identified AS in an additional 13 (total, 48%). AS was detected at 6 months in only three patients but was not detected immediately after PMV. Although AS is very frequent immediately after PMV, Qp/Qs is usually less than 1.5. The appearance of shunting correlates with patient characteristics and with less improvement in valve area after PMV. Atrial shunting usually persists at 6 months, but its severity almost always decreases.

Blood Circulation↗
PubMed1990

[Coronary artery-right ventricular fistula in a patient with heart transplantation. A complication of endomyocardial biopsy].

Two cases of coronary artery right ventricular fistula were diagnosed during the yearly check-up of 38 of the 66 cardiac transplant patients of the Montreal Heart Institute between September 1982 and April 1989. In one case, the fistula involved the right anterior ventricular branch of the right coronary artery and in the other case, a septal branch of the left anterior descending artery. Histological examination of the biopsy fragments obtained before diagnosis of the fistula showed the presence of small calibre arteries, which was not the case in 10 control transplant patients. A review of the literature indicates that the risks of endomyocardial biopsy are minimal (less than or equal to 0.5%). However, the possibility of a coronary artery right ventricular fistula should be added to the list of known complications. The resulting shunt is negligible and has no haemodynamic consequences.

Adolescent↗
PubMed1988

Aspirin and dipyridamole in the prevention of restenosis after percutaneous transluminal coronary angioplasty.

To examine the role of antiplatelet therapy in the prevention of arterial restenosis after percutaneous transluminal coronary angioplasty (PTCA), we conducted a randomized, double-blind, placebo-controlled study in 376 patients. The active treatment consisted of an oral aspirin-dipyridamole combination (330 mg-75 mg) given three times daily, beginning 24 hours before PTCA. Eight hours before PTCA, the oral dipyridamole was replaced with intravenous dipyridamole at a dosage of 10 mg per hour for 24 hours, and oral aspirin was continued. Sixteen hours after PTCA, the initial combination was reinstituted. Treatment was continued in patients with a successfully dilated vessel until follow-up angiography four to seven months after PTCA--or earlier, if symptoms dictated. Of 249 patients who underwent follow-up angiography, 37.7 percent of patients receiving the active drug had restenosis in at least one segment, as compared with 38.6 percent of patients taking placebo (P not significant). The number of stenotic segments was virtually the same in the two groups. Among the 376 randomized patients, there were 16 periprocedural Q-wave myocardial infarctions--13 in the placebo group and 3 in the active-drug group (6.9 percent vs. 1.6 percent, P = 0.0113). Although the use of this antiplatelet regimen before and after PTCA did not reduce the six-month rate of restenosis after successful coronary angioplasty, it markedly reduced the incidence of transmural myocardial infarction during or soon after PTCA. Thus, the short-term use of antiplatelet agents in relation to PTCA can be recommended.

Administration, Oral↗
PubMed1988

Restenosis and progression of coronary atherosclerosis after coronary angioplasty.

The relation between restenosis and progression of atherosclerosis in other coronary segments after angioplasty was studied in 98 consecutive patients with 110 coronary stenoses successfully treated with angioplasty. At early angiographic restudy (5 +/- 2 months after angioplasty) 37 patients (38%) had restenosis (defined as a stenosis greater than or equal to 50% of the luminal diameter or loss of greater than or equal to 50% of the gain achieved by angioplasty); progression of atherosclerosis was observed in 4 patients with and 7 without restenosis (13 versus 11%, p = NS). Ninety of the 98 patients underwent a late angiographic restudy a mean of 34 +/- 11 months after angioplasty. Late restenosis was found in one patient. Progression of coronary artery disease (defined as a greater than or equal to 20% decrease in the diameter of a vessel initially narrowed by greater than or equal to 50% or a greater than or equal to 30% decrease when the initial stenosis was less than 50%) was examined in relation to restenosis in 85 of the 90 patients. It occurred in 9 of 27 patients with and 22 of 58 patients without restenosis (33 versus 38%, p = NS). Restenosis developed more rapidly than did progression of disease. Diameter stenosis increased from 35 +/- 8 to 73 +/- 11% at the early restudy in lesions with restenosis; in lesions with disease progression it increased from 9 +/- 18 to 20 +/- 28% (p less than 0.001) at the early restudy to 53 +/- 21% (p less than 0.001) at the late restudy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Multiple coronary angioplasty: a model to discriminate systemic and procedural factors related to restenosis.

To assess the interrelation of clinical and procedural factors responsible for restenosis, 119 patients undergoing coronary arteriography were studied a mean of 5.8 +/- 3 months after successful multiple percutaneous transluminal coronary angioplasty. In all clinical, angiographic and procedural variables, the 119 patients undergoing repeat catheterization were similar to the 87 patients that did not. Overall, restenosis occurred in 74 (34%) of 215 lesions. Sixty-three patients had no restenosis, 44 had at least one restenosis and 12 had restenosis at all angioplasty sites. The statistical distribution of restenoses did not follow a binomial model, suggesting that restenosis is more than a lesion-specific phenomenon. Of all the clinical and procedural variables assessed by multivariate logistic regression analysis, only percent stenosis before angioplasty (p less than 0.01), diabetes mellitus (p less than 0.01) and percent stenosis after angioplasty (p less than 0.05) were predictive of restenosis in the entire group. Patients with no restenosis and patients with restenosis at all sites were not different with respect to procedural variables; however, patients with restenosis at all sites more often (p less than 0.05) had diabetes and recent onset angina. In contrast, patients with no restenosis differed from patients with isolated restenosis with respect to procedural variables: severity of stenosis before and after angioplasty, balloon/artery lumen ratio and maximal inflation pressure. Thus, procedural factors may be more related to isolated restenosis, but patient-related factors such as diabetes and recent onset angina may play a more important role in patients with multiple restenoses.

Aged↗
PubMed1988

Aortic valve replacement with the Carpentier-Edwards pericardial bioprosthesis: clinical and hemodynamic results.

From 1981 to 1987, 189 patients underwent isolated aortic valve replacement with the Carpentier-Edwards bovine pericardial bioprosthesis. There were 9 early deaths (30-day mortality of 4.8%) and 18 late deaths (3.3% pt-yr). After 5 years, the actuarial survival rate was 81.9%. All patients but one were followed for an average of 37 months after operation, and follow-up totaled 551 patient-years. Valve-related complications included 12 thromboembolic episodes (2.2%/pt-yr), 7 endocarditis (1.3%/pt-yr), 2 hemorrhages due to anticoagulation (0.4%/pt-yr), and 3 reoperations (0.5%/pt-yr). After five years, freedom from thromboembolic events was 91%, that from reoperation was 98%, and 87% for all valve-related complications. There was no primary tissue failure of the valve. Before operation, 55% of the patients were in functional Class III or IV, 97% of the survivors were in Class I or II after valve replacement. Hematological evaluation of 77 patients, an average of 18 months postoperatively, showed no clinically significant hemolysis. Postoperative hemodynamic studies in 28 patients showed mean aortic pressure gradients across the prosthesis at rest ranging from 24 mmHg with the smaller (19 mm) to 11 mmHg with the larger (25 mm and more) valves, and effective orifice areas ranging from 1.0 to 1.9 cm2, respectively. Thus, the Carpentier-Edwards pericardial bioprosthesis appears to be a reliable and hemodynamically effective substitute for replacement of the aortic valve.

Adult↗
PubMed1987

Early results, complications and restenosis rates after multilesion and multivessel percutaneous transluminal coronary angioplasty.

Initial results, complications, restenosis rates and clinical outcomes were compared in 78 patients undergoing multilesion and 128 patients undergoing multivessel percutaneous transluminal coronary angioplasty (PTCA). Multilesion PTCA was defined as a procedure in which a proximal PTCA site had to be crossed to dilate a distal severe narrowing and multivessel PTCA as multiple dilatations without having to cross 1 severe narrowing to dilate another. The clinical and angiographic features of the 2 groups were similar. More sites per patient were attempted among those who underwent multilesion PTCA. Primary success rate per lesion was 86% (236 of 274) among those who underwent multivessel and 73% (155 of 211) among those who underwent multilesion PTCA (p less than 0.001). A success rate of 81% (101 of 124) for proximal lesions among those with multilesion PTCA was not significantly worse than that for those with multivessel PTCA; however, lesions distal to proximal sites had a success rate of only 62% (54 of 87), worse than either those with proximal stenoses or multivessel PTCA (p less than 0.005). Arterial diameter, severity of stenosis or procedural variables did not account for this difference. Complication rates were similar in the 2 groups. Despite a poorer success rate among patients with multilesion PTCA, clinical improvement to functional class 0 or 1 occurred in more than 70% of patients in both groups and was equal in patients with and without successful distal dilatations. Restenosis rates per lesion in patients with multivessel (31%) and multilesion (30%) PTCA were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Restenosis after successful percutaneous transluminal coronary angioplasty: the Montreal Heart Institute experience.

Repeat coronary angiography was performed within 6 months after successful percutaneous transluminal coronary angioplasty (PTCA) in 178 of our first 181 patients (98%). The remaining 3 patients were symptom free, had negative treadmill exercise test results and were considered not to have had restenosis. A second follow-up angiogram was performed in 107 patients (59%), including all patients with persistent or recurrent anginal symptoms, between 7 and 18 months after PTCA. Fifty-one of the 181 patients (28%) had restenosis on 51 of 205 successfully dilated segments (25%). The stenosis was greater than or equal to 70% in 49 of these 51 segments; it was 65% and 55%, respectively, in the 2 remaining patients. Restenosis was documented angiographically at a median time of 4.7 +/- 4 months. However, 47 patients (92%) had restenosis documented within 6 months, 2 between 7 and 12 months and 2 between 13 and 18 months after PTCA. Stepwise logistic regression analysis selected the following factors as independent predictors of restenosis after PTCA: variant angina, multivessel disease, severity of residual stenosis and less reduction in the diameter of the stenosis on the angiogram immediately after PTCA. Of these 4 factors, the degree of residual stenosis immediately after PTCA was by far the most significant. It is concluded that restenosis occurs in approximately 25% of patients, almost always within the first 6 months, after successful PTCA. The degree of residual stenosis after PTCA is the most important predictor of restenosis. Increased experience and improved instrumentation may eventually lead to less residual stenosis and better late results after PTCA.

Angioplasty, Balloon↗
PubMed1987

Intravenous streptokinase and percutaneous transluminal coronary angioplasty in acute myocardial infarction.

Intravenous streptokinase already has been demonstrated safe and beneficial in acute myocardial infarction. The adjunction of early angiography seems to be safe, providing the possibility of full revascularization in a larger number of patients with a high rate of primary success. The improvement of global ventricular function, the reduction of mortality, post infarction angina and reocclusion have to be confirmed by longer follow-up.

Angioplasty, Balloon↗
PubMed1987

Clinical and hemodynamic assessment of the Omniscience prosthetic heart valve.

From 1980 to 1985, 154 Omniscience valve prostheses were implanted in 132 patients (mitral in 72, aortic in 33, and both in 27), 81 women and 51 men, aged 22 to 72 years. There were 13 early deaths (30 day mortality of 9.8%) and nine late deaths. The actuarial survival rate was 79.1% after 4 years, and survival rates after aortic, mitral, and multiple valve replacement were 71.8%, 80%, and 85.2%, respectively. After a postoperative follow-up period averaging 27 months, 96% of the survivors were in Class I or II. The linearized incidence of thromboembolism, hemorrhagic episodes, and reoperation was 3.8%, 3.4%, and 2.3% per patient-year, respectively. After 4 years, freedom from valve-related mortality, valve-related mortality and reoperation, thromboembolic episodes, and all valve-related complications was 93%, 89%, 88%, and 70%. Moderate hemolysis with increases of reticulocyte count and serum lactic dehydrogenase above normal values was found in 80% of the patients, but only one had hemolytic anemia. In 22 patients, the maximal opening angle of the prosthetic disc averaged 54 +/- 11 degrees. Postoperative hemodynamic evaluation was obtained in five patients with aortic prostheses and in 13 with mitral prostheses. Mean aortic gradient and effective orifice area averaged 17.6 mm Hg and 1.2 cm2 at rest and increased to 18.8 mm Hg and 1.7 cm2 with exercise. With mitral prostheses, these values averaged 6.5 mm Hg and 1.9 cm2 at rest and 15.4 mm Hg and 2.1 cm2 with exercise. Thus excellent clinical improvement is obtained with the Omniscience prosthesis; however, the hemodynamic performance of the valve and opening of the tilting disc are suboptimal, causing the prosthesis to be moderately obstructive to blood flow.

Actuarial Analysis↗
PubMed1986

Atrial natriuretic factor in human plasma.

A reproducible and sensitive radioimmunoassay (RIA) was developed to measure ANF in human plasma. Immunoreactive ANF was extracted from plasma with Sep-Pak cartridges, using 0.2% ammonium acetate (pH 4) with acetonitrile. The sensitivity of the assay was 3.9 pg/ml. The coefficient of variance for inter-assay and intra-assay was 16.8% and 6.8%, respectively. In normal healthy subjects (n = 67), ANF content was 11.9 +/- 1.3 pg/ml (mean +/- SEM). Significantly-higher ANF concentrations were found in proximal coronary sinus blood, being 6 to 37 times greater than in the peripheral circulation. Comparison of the prior extraction method with direct RIA revealed a good correlation (r = 91) in samples containing higher than 100 pg/ml ANF. No correlation was observed with lower values. The elution profiles of reverse-phase HPLC of peripheral and coronary sinus plasma extracts were similar but somewhat complex, with the main immunoreactive peak corresponding to a low-molecular-weight peptide.

Adult↗
PubMed1986

Risk of preangioplasty occlusion and myocardial infarction in one-vessel-disease patients scheduled for percutaneous transluminal coronary angioplasty.

Coronary occlusion or myocardial infarction occurred in 50 of 394 (13%) one-vessel-disease patients awaiting percutaneous transluminal coronary angioplasty (PTCA). To identify risk factors for these events, we first matched the 37 patients who demonstrated occlusion on the immediate preangioplasty repeat angiogram with 37 patients who did not. Matching was based on the time interval between angiograms, the date of the procedure, and the site of the lesion. Preangioplasty occlusion patients did differ from controls by age (47 +/- 11 vs 54 +/- 8 years, P less than .01), smoking status (34/37 vs 24/37, P less than .01), and angina class (2.6 +/- 1.0 vs 2.3 +/- 0.7, P less than .10) at the time of the first angiogram. Second, we pooled the data of the 37 preangioplasty occlusion patients with those of the 13 patients with preangioplasty myocardial infarction. The 50 cases with complication (coronary occlusion or myocardial infarction) were younger (47 +/- 12 vs 54 +/- 8 years, P less than .01), more often smokers (42/50 vs 24/37, P less than .05), and more symptomatic (2.7 +/- 0.8 vs 2.3 +/- 0.7, P less than .05) than the 37 controls. This study suggests that young smokers with severe angina are at high risk of preangioplasty occlusion and/or myocardial infarction; prompt management of these patients, when considered for PTCA, seems advisable.

Angiography↗
PubMed1986

[Evaluation of new pericardial bioprostheses by pulsed and continuous Doppler ultrasound ].

The authors have studied by pulsed and continuous Doppler ultrasonography 108 pericardial prostheses in a good functional state implanted for less than five years to patients without any clinical and echographic signs of heart failure. The pulsed Doppler ultrasonography allowed to exclude the possible dysfunction of the prostheses; continuous Doppler ultrasonography allowed the measurement of the maximal transprosthetic velocities and to deduce the corresponding maximal and middle gradients by means of simplified Bernouilli's equation. Using three types of bioprostheses (Carpentier-Edwards, Ionescu and Mitroflow) the following problems were investigated: Normal ranges of maximal transprosthetic velocity and gradients. At the aortic level the maximal velocity ranges from 1.60 to 2.83 +/- 14 m/s and the maximal gradients from 10 for size 27-29 to 32 +/- 3.3 mmHg for size 19. At the mitral level the maximal velocity ranges from 0.80 to 2 m/s and the mean gradients from 1 for size 33 to 7 mmHg for size 25. The mean half-life of decrease is 100 +/- 28 ms. Thus all aortic bioprostheses appear to be stenosing, which is not the case for the mitral ones, size 31 and 33. Factors governing the maximal transprosthetic velocity and the gradients: these determining factors are the size, the type and the age of the bioprosthesis (r = 0.59 for the correlation between maximal velocity and size, r = 0.53 between size and mean aortic gradient). The accessory factors are the age and the functional condition of the myocardium. All these factors have to be considered and neutralized for allowing a valid comparison of various types of prostheses. Comparison of the three pericardial prostheses studied: in patients without signs of myocardial dysfunction of prosthetic origin and with comparable basal conditions, comparison of maximal velocity and of the gradient points to a significant superiority of the Mitroflow at the aortic level and of the Ionescu and Mitroflow at the mitral level. It should be noted in the end that the great similarity of the results obtained in the present study by Doppler ultrasonography with the previously reported hemodynamic data confirms the important role of the Doppler method in the evaluation of valvular bioprostheses.

Adult↗