Biomedical subjects

R Melgares

Publications and source records attributed to R Melgares.

15 recordsLinked to original sources

PubMed2001

[Initial results and 6 month clinical follow-up after implantation of a silicon carbide coated coronary stent].

INTRODUCTION AND OBJECTIVES: To present the initial Spanish experience with the Tenax coronary stent, a laser sculpted from high-precision 316L stainless steel coated with hydrogen rich amorphous silicon carbide that reduces thrombogenecity and improves biocompatibility. PATIENTS AND METHODS: From July 1998 to July 1999, 206 patients (62 +/- 5 years) underwent implantation of 231 Tenax stents in 9 centers as the only revascularization procedure. The most frequent clinical indication was unstable angina (66%), and most of the lesions were complex (class B2 and C). The target vessels were the left anterior descending (51%) and right coronary arteries (36%). The ejection fraction was < 0.5 in 19% cases. RESULTS: Revascularization was complete in 70%, elective in 80%, and the implantation was direct in 25% of the cases. The procedure was successful in all the lesions, reducing stenosis from 62 +/- 16 to 16 +/- 10% and increasing the minimal luminal diameter from 0.81 +/- 0.40 to 2.61 +/- 0.59 mm. The TIMI flow was reduced in 30%, but normalized after the stent in all but one case. The incidence of cardiac events was minimal: 1 acute thrombosis (0.5%) resolved by a new angioplasty and 1 non-Q myocardial infarction (0.5%). At the 6-month clinical follow-up 10% of the patients presented complaints of angina greater than class II, and a new angioplasty was carried out in 1.9% of these cases. CONCLUSION: Clinical and angiographic data suggest that the hydrogenated silicon carbide coating of the Tenax coronary stent may indeed play a beneficial role in patient outcome, and should therefore be evaluated by prospective clinical trials.

Angina, Unstable↗

PubMed1997

[Usefulness of the angiographic examination of the left internal mammary artery in patients candidates for coronary bypass surgery].

BACKGROUND AND OBJECTIVE: The usefulness of preoperative angiographic evaluation of the internal mammary artery (IMA) is controversial. The aim of this study is to evaluate the problem by a basic cost-benefit analysis. METHODS: One hundred and twenty-one patients whose coronary findings (left main disease and/or severe stenosis of the left anterior descending artery) made use of the IMA as a bypass graft a consideration were studied. The IMA was cannulated by the same right Judkins catheter used in the coronarography; the specific catheter was only used if the cannulation was not successful with the right Judkins. We measured the time it took for a good angiography of the IMA to be obtained; the anatomy and the size for each IMA were studied and compared with the size of the left anterior descending artery. RESULTS: An optimal angiographic picture of the IMA was obtained in 119 cases (98.3%); a specific catheter was used only in 3 patients. The mean of the time employed was 170 seconds (8-900 s) and no complications were related to IMA cannulations. Angiography findings relevant to any planned surgery were demonstrated in 15 patients (12%): large proximal branches (10); occlusion stenosis or a caliber insufficient for IMA (3); and occlusion or proximal subclavian stenosis (2). CONCLUSIONS: We have observed that the relation between the cost and the obtained information is adequate to warrant its performance, because angiographic findings relevant to planned surgery can be very important, even though they are fairly infrequent. Moreover, these findings can be achieved rapidly without additional cost.

Coronary Angiography↗

PubMed1995

The value of exercise electrocardiography testing in the identification of coronary restenosis: a probability analysis.

We studied by means of probability analysis the role of exercise ECG in identifying coronary restenosis. A total of 213 patients were independently evaluated by clinical history, conventional assessment of the exercise ECG ('yes or no' statement), D score (a discriminant function derived from exercise ECG), and coronariography, 5.4 +/- 2.8 months after successful coronary angioplasty. The initial probability of restenosis (30%), that is, the prevalence of the condition, was radically changed by the result of clinical history (77% for patients with angina vs. 17% for those without angina). By contrast, ECG binary assessment, due to its low accuracy (70% vs 82% of clinical history, P < 0.005), was unable to significantly change the established probabilities after symptomatic evaluation. Finally, D score, which greatly enhanced specificity (92% vs. 76% of bivariate assessment, P < 0.0001), proved to be useful in changing the probability (from 32% to 76% or to 25%) of patients (n = 34) with a discordant result (no angina/positive exercise ECG). When this stepwise approach was tested in 46 new patients, predicted and observed probabilities were actually very similar. We conclude that exercise ECG has a very limited role in identifying coronary restenosis if positive responses are not adjusted with a weighted score which takes into account other exercise derived factors.

Angina Pectoris↗

PubMed1993

Significant coronary restenosis limits the recovery of regional left myocardial dysfunction achieved after successful coronary angioplasty.

Impaired regional left ventricular function has been shown to improve after successful transluminal coronary angioplasty, but there are no data concerning the effect of coronary restenosis on this recovery. Therefore, the short- (1 month) and midterm (5.5 months) evolution of systolic regional left ventricular function was prospectively investigated in 41 patients undergoing successful coronary angioplasty. In patients with resting hypokinetic areas before angioplasty and no restenosis (n = 8), regional function improved from -6.0 +/- 2.9 to -2.9 +/- 2.4 SD/segment (P < 0.01) in the short-term, without further significant changes at mid-term. Patients with hypokinetic areas and coronary restenosis > or = 70% (n = 15) also showed early functional recovery from -5.1 +/- 2.2 to -1.4 +/- 2.5 SD/segment (P < 0.00001) but, in contrast with the other subset of patients, a significant reduction to -3.9 +/- 2.3 SD/segment (P < 0.0001) was observed at mid-term. In spite of this, regional function was still better than before angioplasty (P < 0.01). No significant changes were observed in patients without either asynergy or restenosis (n = 16). The small number of cases without preliminary hypokinesis and development of restenosis > or = 70% (n = 2) precluded an analysis of this situation, but a new and severe hypokinetic defect was recognized in one patient in a later study. We conclude that the improvement in regional myocardial function observed early after successful dilation of the culprit vessel is partially lost when significant restenosis develops.

Adult↗

PubMed1993

[Probability analysis of the value of ergometry in the detection of restenosis after coronary angioplasty].

To evaluate the usefulness of treadmill exercise test in the diagnosis of coronary restenosis, we have chosen a sequential and probabilistic analysis. The rate of coronary restenosis found in the sample (n = 213) was of 30%. This initial probability of having restenosis was radically changed by the recurrence of typical angina: 77% in patients with this symptom, 17% in those without (p < 0.001). In contrast, the qualitative result of the exercise test was unable to change significantly the probabilities established after anamnesis. This was due to a lower specificity for exercise test (76%) than for angina (93%), the sensibility being the same (56%) for both. Employment of a discriminant value that integrates different ergometric variables did not enhanced sensibility, but allowed the identification of a good number of false positive results and therefore palliated the negative impact of faulty specificity. Being applied to a "discordant group" (no angina/positive exercise test, n = 34) was able to achieve a significant change in probability: from 15% to 50% or 4% (p < 0.01), according to the discriminant being lesser or greater than a preestablished value. In conclusion, prevalence of the event and evaluation of symptomatology are both important to estimate the probability of suffering coronary restenosis. On the contrary, exercise test, in the absence of a weighty method, adds more confusion than clarity to the analysis of the problem. Our results can be used to improve the follow-up of patients who have been successfully dilated by angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed1991

Success determining factors in percutaneous transluminal balloon valvuloplasty of pulmonary valve stenosis.

Twenty-two percutaneous transluminal balloon valvuloplasty procedures were performed on 21 patients with congenital pulmonary valve stenosis. The peak systolic pressure gradient was immediately reduced from 79.1 +/- 7.4 to 22.2 +/- 1.8 mmHg, (P less than 0.0001) and follow-up cardiac catheterization at 5.3 +/- 0.4 months in 19 patients revealed no further significant change in gradient (23.5 +/- 3.2 mmHg). The best results were obtained when balloons larger than the pulmonary annulus were used, i.e. an immediate residual transvalvular gradient of 22.0 +/- 2.2 mmHg with a balloon/annulus ratio greater than 1, as opposed to 44.2 +/- 5.4 with a balloon/annulus ratio = 1 (P less than 0.001). The angiographically determined cusp thickness of the stenotic pulmonary valves was significantly greater than that of the control group of 24 patients without pulmonary valve stenosis (1.21 +/- 0.09 vs 0.59 +/- 0.02 mmHg, P less than 0.00001). The relationship between this parameter and the residual transvalvular gradient at follow-up was found to be significant (r = 0.77, P less than 0.001). It is concluded that balloon size is a determinant factor in achieving good results with percutaneous balloon valvuloplasty although cusp thickness, a factor to which scant regard has hitherto been paid, also plays a significant role in the residual transvalvular gradient measured at follow-up.

Adolescent↗

PubMed1989

[Diverticulum of the right ventricle].

We report the case of a 38-year-old woman who underwent cardiac catheterization because of cyanosis from birth. This study revealed a right ventricular cavity hypoplasia, an atrial septal defect, and a diverticulum originated from the free right ventricular wall. Ventricular diverticuli, especially those in the right ventricle, are very rare malformations, usually associated with other cardiac defects. The right ventricular diverticulum is generally non-symptomatic, diagnosed by chance, and does not usually require surgical treatment.

Adult↗

PubMed1989

[Transluminal angioplasty for aortic coarctation in newborns and infants].

It has been done transluminal angioplastic with catheter balloon in 14 patients who are under 1 year of age and who are affected by aortic coarctation. For this study, they were divided in two groups. The first one was formed by newborn children whose transcoarctation gradient was 52 mm Hg in average. The second group was integrated by 9 newborn children whose transcoarctation gradient was 59 mm Hg. After this experience was done the gradient descended to 9 and 15 mm Hg respectively. Twenty four hours later, two months later and over two more months, there were follow-up of the clinical situation, the evolution of the pulse, differential arterial pressure and the need of surgery. Of the first group only one of the patients, who is now 2 years old, is in good clinical condition; the others needed to be surgically intervened. Of the second group 4 patients, all of whom were over 3 months old at the time of the angioplastic had positive results. The rest needed surgical intervention.

Angioplasty, Balloon↗

PubMed1989

[Aortic stenosis with left ventricular systolic dysfunction: a severe disease but with good surgical prognosis].

From our series of 72 patients with severe valvular aortic stenosis, we identified 19 showing features of left ventricular systolic disfunction (ventriculographic ejection fraction less than 55% and/or fractional shortening less than 30% at M-mode echocardiography). In these patients, we found a significant inverse correlation between the fractional shortening and the systolic wall stress (r = 0.79, p less than 0.001). Clinically, 18 of the 19 patients were in NYHA class III (n = 11) or IV (n = 5), and two died before they could be operated upon. The remaining 17 had their aortic valve replaced (coronary artery bypass surgery was simultaneously performed in 2 patients). After a mean follow-up of 18 months, all patients are alive and show substantial symptomatic improvement (15 patients in class I and 2 patients in class II). Cardiothoracic index was reduced (61 +/- 5% preoperatively versus 52 +/- 5% postoperatively), and fractional shortening changed from 21 +/- 5% to 30 +/- 5%. The latter remains under normal limits in two thirds of the patients. Our results lend support to the idea that the systolic left ventricular dysfunction in aortic stenosis is due to the increased afterload, rather than to an intrinsic contractility defect. This explains the great functional improvement after the reduction of the systolic wall stress achieved by surgery.

Adult↗

PubMed1989

[Quantitative evaluation of the exercise test using discriminant analysis].

One hundred and twenty seven selected patients had treadmill tests and coronary angiograms. Eight variables were correlated by discriminant analysis to the presence and extent of coronary artery disease (CAD) in a two-way approach. In the first (43 patients without significant CAD versus 84 with significant CAD), two ergometric (maximal heart rate achieved and exercise time) and two common (age and sex) variables merged as predictors. In the second approach (65 patients without CAD or CAD with a little amount of myocardium at risk versus 62 with CAD and a greater extent of jeopardized myocardium), the two clinical variables were replaced by two new ergometric predictors: the level of ST depression and maximum systolic blood pressure reached. Comparatively with the conventional assay of exercise test, the second discriminant function (Z2) enhanced specificity (67 versus 84%) but impaired sensibility (82 versus 70%); nevertheless, this late index was preserved (93 versus 89%) in the 3-vessel CAD group. Moreover, the Z2 value decreased as the severity of CAD increased; the differences between groups were significant (p less than 0.01) up to the level of 2-vessel versus 3-vessel CAD where the trend persists but failed to be significant. Likewise, within the 1-vessel CAD group, the mean Z2 value was lower (p less than 0.01) when the narrowing was located in the proximal portion of the left anterior descending coronary artery. This quantitative approach to the exercise test was validated in a new series of 85 patients and, in our opinion, could be useful for making patient care decisions.

Angiocardiography↗

PubMed1982