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Biomedical subjects

A Medina

Publications and source records attributed to A Medina.

At least 19 recordsLinked to original sources
PubMed1992

Peripheral stent recovery after failed intracoronary delivery.

The Palmaz-Schatz stent can be successfully deployed in most patients. However, in a small percentage of instances a systemic embolism of the stent has been reported. In the present article we describe an easy and fast method of stent capture when detachment from the balloon has happened (pulling back the stent-loaded balloon into the guiding catheter or femoral sheath). In this situation we propose the use of the coronary guide-wire "as a guide" to capture coaxially the lost stent. This method allows for continuing the procedure without removal of the femoral sheath.

Aged↗
PubMed1992

Structural changes in sperm from the fiddler crab, Uca tangeri (Crustacea, Brachyura), during the acrosome reaction.

The acrosome reaction (AR) was induced in sperm from the brachyuran crustacean Uca tangeri either by mixing male and female gametes in filtered seawater or by treating the spermatozoa with the divalent cation ionophore A23187. This latter method provided a sufficient number of reacted spermatozoa to allow a detailed ultrastructural study of the AR. The process consists of two separate phases: a) initial release of the acrosomal vesicle contents, and b) further elongation of the acrosomal filament, which causes reversal of the rigid capsule limiting the acrosomal vesicle contents. The elongate acrosomal filament consists of an apical perforatorium and a basal columnar structure called here the proximal piece. The former derives from the perforatorium of the uninduced sperm stage with only small ultrastructural changes. The proximal piece forms from myelin-like membrane layers which are initially distributed all around the subacrosomal region and then accumulate in a column at the perforatorial base, thus promoting a sudden forward projection of the perforatorium. The AR in brachyurans is thought to be a passive mechanism that utilizes the negative pressure exerted on the nucleus--caused by emptying of the acrosomal vesicle--for an organized accumulation of membrane-rich material immediately behind the perforatorium, with the final result of the raising of a 3 microns long acrosomal filament.

Acrosome↗
PubMed1992

Effect of benazepril on myocardial ischaemia in patients with chronic stable angina pectoris.

The anti-ischaemic properties of benazepril, a non-sulfhydryl inhibitor of angiotensin-converting enzyme, were assessed in 20 patients with chronic stable angina pectoris, by repeated exercise tests and repeated 72-h ambulatory electrocardiographic monitoring. The study was a double-blind, placebo-controlled cross-over; 11 patients received benazepril 10 mg b.i.d. and nine received 20 mg b.i.d. All patients had a positive treadmill stress test and at least three ischaemic episodes during 24 h of ambulatory electrocardiographic monitoring. Benazepril at a dose of 10 mg b.i.d. did not improve the exercise duration, the time taken to reach 1 mm ST depression. Similar findings were observed during treatment with 20 mg b.i.d. Benazepril at a dose of 10 mg b.i.d. was ineffective in improving ischaemic parameters during daily activities. However, among the nine patients who received 20 mg b.i.d. the number of ischaemic episodes was reduced from 142 to 103, and the total duration of ischaemic was reduced from 1099 to 531 min. The number of weekly anginal attacks was reduced from 58 to 33, and the weekly sublingual nitroglycerin tablets consumption was reduced from 31 to 14. When the two doses (10 mg and 20 mg) were combined (N = 20), the number of ischaemic episodes was reduced from 314 to 260 (P = 0.074), and the duration of ischaemic was reduced from 3453 to 2514 min (P = 0.072).

Aged↗
PubMed1992

[Follow-up study after percutaneous mitral valvuloplasty. The COR-PAL experience].

Mitral balloon valvulotomy has proven to be an effective method for the treatment of patients with mitral stenosis. Although several factors determining an optimal immediate result have been described, there is few information regarding the longterm follow-up as well as factors influencing late success after the procedure. In this article, we analyzed our series of 311 patients treated by mitral balloon valvulotomy who were clinically followed between 3 months and 5 years (mean 23 +/- 11 months). At least, one echo-Doppler follow-up study was obtained in 260 patients, 20 +/- 10 months after. Hemodynamic re-evaluations were performed in 63 patients after 20 +/- 11 months. Late success was defined as the patient being in functional class I-II and free of major events (death, restenosis or valve surgery). Restenosis was defined as the loss of 50% of initial gain in terms of valve area, confirmed always hemodynamically. Major events during follow-up period occurred in 19 patients (10 deaths, 8 restenosis and 11 mitral valve surgery). We performed a multivariate study using the Cox-regression model. In the analysis, all variables with or near statistic significance in the univariate analysis (Mantel-Haezel) were included. The only significant independent predictors of late success were the presence of sinus rhythm (p < 0.04) and the absence of calcium at the valve (p < 0.001). In conclusion, the best results 5 years after mitral balloon valvulotomy are observed in patients with non calcified valve and sinus rhythm.

Adult↗
PubMed1992

A simple carbon monoxide breath test to estimate erythrocyte turnover.

Carbon monoxide is stoichiometrically released when heme is converted to bilirubin. This report describes and validates a novel technique that permits the estimation of heme turnover and red blood cell survival from the carbon monoxide concentration of end-expiratory breath samples. The end-alveolar Pco of a subject was corrected for environmental carbon monoxide exposure with a simple device that equilibrates with atmospheric carbon monoxide at the same rate as does the subject. The resultant value (endogenous Pco) was tested for its ability to predict heme turnover and red blood cell survival. Red cell survival times of 32 healthy subjects, as calculated from the endogenous Pco, averaged 101 +/- 19 days, a value close to the expected 110-day survival time; 13 patients with clinical evidence of shortened red blood cell survival times had measured erythrocyte life spans ranging from 10 to 59 days. The endogenous Pco of each of seven patients increased after red blood cell transfusion, demonstrating that this technique detected the known rapid turnover of a small fraction of transfused cells. A good correlation (r = 0.91) was observed between heme turnover calculated from endogenous Pco and total fecal biliary pigment output. Carbon monoxide measurements reflect red blood cell destruction in both the marrow and the circulation, therefore yielding shorter life spans than did chromium 51 survival studies. This breath test appears to yield a rapid, semiquantitative assessment of heme turnover and red blood cell survival that is not provided by any other presently available technique. This simple, noninvasive carbon monoxide breath test may find widespread use in the evaluation of anemia and jaundice.

Adult↗
PubMed1991

Immediate and follow-up results of transluminal balloon dilation for discrete subaortic stenosis.

This study presents the findings in 33 patients with discrete subaortic stenosis who were treated by percutaneous balloon dilation and were followed up for 2 months to 6.2 years (mean 34 +/- 21 months). The mean age was 13 +/- 11 years; 10 (30%) were female and 23 (70%) male. Associated malformations were observed in nine patients (27%). All patients underwent noninvasive studies and cardiac catheterization. The mean value to membrane distance was 4.5 +/- 2 mm/m2. After balloon dilation, the pressure gradient from the left ventricle to the aorta decreased from 68 +/- 30 to 20 +/- 13 mm Hg (p less than 0.00001); there were no significant changes in the degree of aortic regurgitation. A fluttering and widely mobile remaining membrane was clearly visualized after dilation. Better immediate results were obtained in patients with a smaller baseline gradient, a larger aortic anulus and a longer valve to membrane distance. Serial follow-up echographic studies were available in 30 patients, and 18 hemodynamic reevaluations were performed in 13 patients. However, seven patients who demonstrated restenosis underwent redilation at a mean of 29 +/- 17 months after the first dilation. Redilation in six of the seven patients obtained benefits similar to those observed at the first dilation. Only one patient with unsuccessful redilation required surgery. The mean value of the last explored residual gradient (on hemodynamic or Doppler study) in the remaining 32 patients was 21 +/- 10 mm Hg. No significant changes were observed in the angiographic evolution of aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Usefulness of severity of myocardial ischemia on exercise testing in predicting the severity of myocardial ischemia during daily activities.

To determine the relation between myocardial ischemic indexes on exercise testing and on ambulatory Holter recording, 60 patients with stable coronary artery disease who exhibited an ischemic response to both testing procedures were studied. All patients performed a Bruce protocol exercise test and underwent 24-hour Holter recording within 2 weeks without antianginal medications. Mean exercise duration was 7.4 +/- 2.8 minutes, mean heart rate at 1-mm ST depression was 118 +/- 20 beats/min and mean maximal ST depression during exercise was 2.2 +/- 1 mm. During Holter recording the average number of ischemic episodes was 4.7 +/- 2.6 per patient, mean duration of daily ischemia was 62 +/- 54 minutes, mean maximal ST depression was 3.2 +/- 1.3 mm and average heart rate at 1-mm ST depression was 93 +/- 17 beats/min. Overall, the correlations between ischemic indexes on both testing procedures were very weak (mean r2 = 0.054). The only exercise variable that had a significant correlation (p less than 0.05) with all Holter variables was heart rate at 1-mm ST depression, yet it correlated very weakly (0.064 less than or equal to r2 less than or equal to 0.125) with most Holter covariates and had a better correlation (r2 = 0.256) only with average heart rate at 1-mm ST depression during Holter. Thus, ischemic indexes on exercise testing cannot accurately predict ischemic indexes on ambulatory Holter recording in patients with stable coronary artery disease who exhibit ischemic changes on both tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1991

Effects of nisoldipine on myocardial ischemia during exercise and during daily activity.

The antiischemic properties of nisoldipine, a dihydropyridine calcium antagonist, were assessed in a multicenter, double-blind, placebo-controlled trial by repeated exercise testing and 72-hour ambulatory electrocardiographic monitoring in 82 patients with coronary artery disease. Patients with positive treadmill stress test results and greater than or equal to 2 ischemic episodes per 24 hours were included in this study. Administration of all chronic antiischemic medications except beta blockers were discontinued. During the first week all patients received placebo twice daily. During the second and third weeks, 41 patients received nisoldipine 10 mg and 41 patients received placebo twice daily. In the placebo group there were no changes in exercise parameters or in ambulatory electrocardiographic parameters. In the nisoldipine group, exercise duration increased from 403 to 448 seconds (p = 0.0035), time to 1 mm of ST depression increased from 224 to 298 seconds (p = 0.002), time to pain increased from 241 to 321 seconds (p = 0.01), and maximal ST depression was reduced from 2.6 to 2.3 mm (p = 0.002). Among the ambulatory electrocardiographic parameters in the nisoldipine group, only the number of episodes was reduced, from 14.4 to 11.6 (p = 0.0013) per patient. There was no significant reduction in total ischemic time (132 vs 120 minutes per patient). No significant side effects were observed. This is the largest clinical trial to date on the effects of nisoldipine on myocardial ischemia. The results indicate that nisoldipine was effective in improving all exercise parameters and only partially effective in suppressing ischemia during daily activity.

Activities of Daily Living↗
PubMed1991

Balloon valvuloplasty for mild mitral stenosis.

Of a total number of 288 patients with mitral stenosis treated by percutaneous balloon valvuloplasty, 21 patients had a basal mitral area equal to or greater than 1.5 cm2, as measured hemodynamically. The immediate hemodynamic results of this particular group of patients with mild mitral stenosis are described, as well as the clinical and echo doppler findings at follow-up (22 +/- 12 mo). Patients with mild mitral stenosis (group I) had more pliable valves (p less than 0.01), as assessed by echo, and higher incidence of sinus rhythm (p less than 0.02) than that observed in the remaining 267 patients (group II). After valvuloplasty the valve area increased in group I from 1.7 +/- 0.2 to 3.1 +/- 0.7 cm2 (p less than 0.0001). This mean final area was significantly different (p less than 0.0001) than that observed in group II (1.98 +/- 0.6 cm2). No patients with mild mitral stenosis developed progression of mitral regurgitation, and none had any other major complications. Most of them reached a grade I final functional status. At echo doppler follow-up studies we did not observe significant changes in the mean mitral gradient as compared with the immediate hemodynamic results. These findings suggest that early mitral balloon valvuloplasty could be an alternative in trying to favorably influence the natural course of the rheumatic mitral disease in selected patients.

Adult↗
PubMed1991

False tendon rupture simulating chordal rupture after percutaneous mitral balloon dilation. A report of two cases.

We describe two cases of ruptured false tendons following percutaneous balloon dilation of the mitral valve in one case, and combined mitral and aortic balloon valvotomy in the other, using in both the retrograde approach. The echocardiographic characteristics of this previously unreported complication of the procedure are presented with special emphasis on the differentiation with true chordal rupture. No short or mid term adverse effects were noted following this complication.

Adult↗
PubMed1991

[Transesophageal echocardiography in the selection of patients prior to percutaneous mitral valvuloplasty. Study of 71 consecutive patients].

We studied 71 consecutive patients with mitral stenosis candidates for mitral valvuloplasty by means of transthoracic (TTE) and transesophageal echocardiography (TEE). We compared the information obtained by the two methods with respect to: mitral valve morphology (echocardiographic score), severity of mitral regurgitation, prevalence of atrial thrombus and incidence of spontaneous contrast in the left atrium. The assessment of valvular thickening, mobility and calcification was similar by the two methods. The assessment of the subvalvular disease was significantly lower by TEE than the assessed by TTE (1.66 +/- 0.6 vs 2.12 +/- 0.5; p less than 0.001). The total "score" obtained by TEE was significantly lower than the "score" obtained by TTE (7.32 +/- 1.9 vs 7.88 +/- 1.8; p +/- 0.001), but when we classified the patients in groups according to the "score", there were no significant differences between the groups obtained by the two methods. We detected mitral regurgitation in 27 patients (38%) by TTE and in 36 (50%) by TEE. The difference in the quantification of the mitral regurgitation was no more than one grade in any case. Atrial thrombus were detected in 16 patients (22%) by TEE and in 2 patients by TTE. Spontaneous contrast was seen in 53 patients (75%) by TEE and in only 1 by TTE. We conclude that TEE is essential in detecting atrial thrombus, but does not provide any new information about mitral valve morphology and mitral regurgitation in the selection of patients for percutaneous mitral valvuloplasty.

Adult↗
PubMed1991

[Valvulopathies (XIV). The role of percutaneous valvuloplasty in congenital valvular diseases].

The present article describes the cooperative experience Córdoba-Las Palmas since 1983 in 123 patients with congenital right or left ventricular outflow obstructions who were treated by percutaneous balloon dilatation. Seventy of them had pulmonary stenosis (63 valvular and seven supravalvular types); two had pulmonary atresia, 25 valvular aortic stenosis and 27 discrete subaortic stenosis. In patients with valvular pulmonic stenosis the gradient and the right ventricular pressure decreased significantly. No significant changes were observed in the degree of pulmonary regurgitation. One neonate died. No other major complications occurred. After a mean follow up of 3 +/- 2 years, we did not observe significant changes in the degree of pressure relief. The mean residual gradient is 26 +/- 19 mmHg. In our 21 patients out of the neonatal period with valvular aortic stenosis the gradient and the left ventricular pressure dropped significantly. Progression of aortic regurgitation in more than I grade was observed in 4 patients (19%), although only one (5%) progressed to grade III. There were no major complications in this group. After a mean follow up period of 24 +/- 17 months they persist with the obtained pressure relief and same degree of valvular competence. All 4 neonates with critical aortic stenosis had unsuccessful dilations and they died, wether after ulterior surgery or without it. In 27 patients with discrete subaortic stenosis the gradient and the left ventricular pressure decreased markedly, without significant changes in valve competence. There were no related major complications. After dilation, a broken and mobile membrane was frequently seen. At follow up (24 +/- 18 months), 6 patients (22%) had restenosis; five of them were successfully redilated. The remaining 21 patients persist with a reduced residual gradient (24 +/- 7 mmHg) and without significant changes in valve competence.

Adolescent↗
PubMed1991

[The electronystagmographic protocol for tracking vestibular dysfunction].

This prospective protocol for vestibular exploration offers the results gained through 296 patients complaining from vestibular disorders. The aim of the AA. is to check the validity of the test proposed (in the midst of the battery of electronystagmographic explorations), consisting in the thermal bilateral and simultaneous stimulation of the labyrinths. They consider this trial very useful because of its sensibility, quickness and tolerance.

Electronystagmography↗
PubMed1991

[Coronary permeability and left ventricular function following thrombolytic therapy].

We study 40 patients, 55 +/- 7 years old with acute myocardial infarction treated early by thrombolytic therapy (20 STK and 20 rt-PA). All patients were angiographically studied in the following conditions: 1) baseline, before initiating therapy. 2) Three hours after treatment. 3) Twenty four hours later. 4) Before discharge. The infarct related artery was patent 24 hours after treatment in 31 patients (78%); five of them were patent before treatment, and we observed an early reperfusion in 20 patients (57%) and late reperfusion in 6 patients (17%). The number of patients with angiographic evidence of intraluminal thrombus decreased progressively through conditions while the grade TIMI of coronary perfusion increased in the absence of reocclusion. Final regional wall motion of infarct related myocardial zones and their degree of recovery were significantly higher in recanalized patients, as compared with non-reperfused patients. Similarly, left ventricular functional recovery was higher in patients with antegrade of collateral flow to the infarct area, as compared with totally occluded patients.

Coronary Angiography↗
PubMed1991

[Cardiac rhabdomyoma and tuberous sclerosis. Survival after the surgical resection of the cardiac tumor].

A 3-month-old boy with tuberous sclerosis was diagnosed of biventricular heart tumor by means of 2D-echocardiogram. Three masses of tumor were excised from the right ventricle with the aid of cardiopulmonary bypass. Pathologic examination disclosed a cardiac rhabdomyoma. The boy is symptoms-free after 5 years of the operation. An echocardiogram taken at this time showed no-evidence of heart tumor. Pathology, diagnostic methods and surgical indications are commented. A review of selected surgically resected cases is also presented.

Biopsy↗
PubMed1990

Factors influencing progression of mitral regurgitation after transarterial balloon valvuloplasty for mitral stenosis.

This study analyzes the clinical, echocardiographic and hemodynamic factors affecting progression of mitral regurgitation (MR) after transarterial balloon valvuloplasty in 200 consecutive patients with rheumatic mitral stenosis. After valvuloplasty, the mitral valve area increased in all patients, from 1.03 +/- 0.36 to 2.06 +/- 0.71 cm2 (p less than 0.0001). With regard to the basal stage, the mitral valve was competent in 139 patients and there was mild MR in 61 (grade I in 53, and grade II in 8). Three patients had progression of MR induced by a technical deficiency and they were excluded from analysis. Patients were classified into 2 groups on the basis of the degree of MR before and after valvuloplasty: group A--no progression of MR (n = 167; 85%) when the degree of MR did not change, disappeared after valvuloplasty, or increased from grade 0 to I; group B--progression of MR (n = 30; 15%) when the degree of MR increased to greater than or equal to grade II. Progression of MR was observed more frequently in older patients with presence of chronic atrial fibrillation, larger left atrial size and left ventricular volumes, baseline MR, more severe stenosis and a lower ejection fraction. Multivariate analysis selected age, left ventricular volumes and ejection fraction as independent predictors of progression of MR. All these factors suggest that progression of MR after balloon valvuloplasty could be related to a more advanced degree of disease.

Age Factors↗