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Biomedical subjects

A Medina

Publications and source records attributed to A Medina.

At least 91 records · Page 5Linked to original sources
PubMed1995

Follow-up patency of side branches covered by intracoronary Palmaz-Schatz stent.

To assess the risk of late side branch occlusion after Palmaz-Schatz stent deployment, we analyzed the angiographic evolution of 62 patients treated by successful stent implantation who had a total of 85 side branches starting from the stented segment. Side branches were considered minor (n = 39) when the diameter was < 1 mm and intermediate (n = 46) when the vessel had > or = 1 mm diameter. One angiographic follow-up study was available in all patients at 8 +/- 5 months. Eight minor branches presented some degree of stenosis at origin before stent deployment (4 totally occluded). After stent deployment, 32 (82%) of 39 remained unchanged and 3 became occluded. Late progression at origin occurred in 4 of 34 (3 occluded). Before stent deployment, 48% of the intermediate branches had some compromise degree at their starting point (1 totally occluded). Eight of 45 intermediate branches became occluded after stent implantation. Late progression at origin happened in 5 of 32 branches (2 occluded). Some degree of follow-up stenosis regression at the origin was observed in 22 (26%) of 85 arteries. Neither clinical nor angiographic factors could be identified as predictors of late side branch occlusion or stenosis progression at its origin. Later occlusion or progression at origin of a side branch covered by a Palmaz-Schatz stent seems to be an uncommon occurrence (7% and 12% respectively) that cannot be predicted by angiographic or clinical factors. On the contrary, regression at follow-up of a side branch-origin stenosis can also come about.

Adult↗
PubMed1995

[A new case of congenital leukemia with leukemia cutis].

Congenital leukaemia is a condition occurring very rarely. In a recent review in 1993, 175 cases are reported, 25-30% of them being well documented as leukaemia cutis. We reported a new case of congenital leukaemia diagnosed as an acute non lymphoblastic leukaemia M4 (FAB) and diagnosed at birth. It involves a newborn female at 42 weeks of gestational age. The most relevant clinical features were hepatomegaly and cutaneous petechial lesions along with a generalized distribution of nodules. From the blood peripheral count, leukocytosis is observed (177 x 10(9)/L) with 48% blasts of myeloid immunophenotype. The coagulation studies were consistent with a disseminated intravascular coagulation syndrome. A biopsy carried out on a cutaneous nodule, revealed diffuse dermoepidermic infiltration by immature cells of myeloid lineage, with cellularity and count similar to that of bone marrow and peripheral blood. The karyotype in the peripheral blood was normal. Infectious and immune causes were excluded as well as constitutional illnesses associated with unstable haematopoiesis. The family rejected treatment with chemotherapy and the baby died on day 53 of life due to progressive leukocytosis and concurrent infection. Our case, like 80% of the cases reported, is of myeloid origin and confirms the fatal evolution of untreated congenital leukaemia.

Diagnosis, Differential↗
PubMed1994

Use of alveolar carbon monoxide measurements to assess red blood cell survival in hemodialysis patients.

We recently described a simple technique for measuring RBC survival based on measurements of the concentration of carbon monoxide (CO) in alveolar air, corrected for environmental CO using a device that equilibrates with atmospheric CO at the same rate as does the patient. The purpose of the present report is to demonstrate the clinical utility of this method via measurements of RBC turnover in hemodialysis patients. Prior to dialysis, the mean RBC survival of 9 chronic dialysis patients was 70 +/- 9 days, about 50% shorter than that of 32 healthy subjects. During the dialysis, the endogenous PCO increased by 14% (P < 0.05) while subjects not undergoing dialysis had a 6% fall in endogenous PCO over this same time period. Thus, this technique demonstrated that the hemodialysis procedure resulted in about a 20% increase in RBC destruction. This increased RBC destruction has not been detectable with previous methodologies (including conventional measurements of CO production) due to the insensitivity and lack of reproducibility of conventional techniques. We conclude that the simple, non-invasive measurement of endogenous PCO provides the most accurate available means of assessing the influence of a variety of acute manipulations on RBC survival.

Breath Tests↗
PubMed1994

[AEL: a rare variant of blood group A].

We have studied an eight-member family. Three of them presented discrepancies between red blood cell and serum tests. The red blood cells fail to react with anti-A, anti-B or anti-AB of any origin. On the other hand, serum grouping tests strongly react with group B cells and fail to react with A1 and A2 cells. Then we performed saliva and adsorption/elution studies in order to demonstrate A or H substances in saliva of secretors. We conclude that the blood belonged to an A weak group named Ael.

ABO Blood-Group System↗
PubMed1993

Factors determining late success after mitral balloon valvulotomy.

Mitral balloon valvulotomy (MBV) has proved to be an effective method in the treatment of patients with mitral stenosis. Although several factors determining an optimal immediate result have been described, there is little information regarding long-term follow-up, as well as factors influencing late success after MBV. This study analyzes 350 patients (mean age 46 +/- 12 years) treated by MBV who were clinically followed up between 6 months and 6 years. At least 1 echo-Doppler follow-up study was obtained in 298 patients 28 +/- 14 months after MBV; hemodynamic reevaluations were performed in 66 patients after 23 +/- months. Late success was considered if the patient was in functional class I to II and free of major events (death, restenosis and valve surgery). Restenosis was defined as a 50% loss of initial gain with regard to valve area by echocardiography, which was confirmed hemodynamically. After a mean follow-up of 38 +/- 15 months, 296 patients (84%) remained in functional class I to II, without surgery or the need for an increase in medical treatment. The 5-year Kaplan-Meier survival rate was 94 +/- 1%, whereas restenosis, valve surgery and major event-free probability were 90 +/- 3%, 91 +/- 2% and 85 +/- 2%, respectively. Multivariate study (Cox regression model) identified the presence of sinus rhythm (p < 0.001) and the absence of calcium at fluoroscopy (p < 0.003) as the only independent factors of late success.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Serial angiographic observations after successful directional coronary atherectomy.

This study focuses on the early and late angiographic evolution observed in 82 patients with coronary artery disease who were successfully treated by directional coronary atherectomy (DCA) without adjunctive balloon angioplasty. Qualitative inspections and quantitative measurements were obtained from a selected angled-view projection in the following conditions: (1) before treatment; (2) immediately after treatment; (3) the day after atherectomy; (4) 1 month after; and (5) 6 months after. The appearance of the treated segment 24 hours after the procedure did not differ in 79 patients from that observed immediately after DCA; silent total occlusion occurred in two patients, and one had an aneurysm at the site of resection (all three patients were excluded from the analysis). At the 1-month study restenosis developed in 3 (3.6%) patients; the remaining 76 had identical appearances, with no evidence of renarrowing of the lumen. However, from 1 to 6 months after the procedure restenosis developed in 35 of the remaining 76 (46%) patients, and 41 patients were free of restenosis and symptoms. These findings, which show that early elastic recoil does not occur after successful DCA, are different from the changes observed after balloon angioplasty. At the 1-month observation restenosis is an infrequent but possible phenomenon (3.8%). From this point the healing of the arterial wall leads to no or mild renarrowing (late success); an exaggerated proliferative response produces restenosis.

Adult↗
PubMed1993

Emmetropization as a first-order feedback system.

The existence of a regulatory mechanism that controls the growth of the eye toward emmetropia is generally agreed upon, but such an emmetropization mechanism has never been verified experimentally. This report supports the hypothesis that emmetropization can be described as a feedback process with a first-order equation and establishes a theoretical framework for future study, experimentation, and manipulation of this elusive mechanism. The feedback hypothesis has been tested by comparing two models. The first is a first-order feedback system, the second a non-feedback model with an almost identical equation. The feedback model fits data from human subjects significantly better.

Adolescent↗
PubMed1993

Intracoronary ultrasound assessment of directional coronary atherectomy: immediate and follow-up findings.

OBJECTIVES: This study was conducted to assess the relations among intracoronary ultrasound, angiographic and histologic data obtained from patients with coronary artery disease successfully treated by directional coronary atherectomy. In addition, it was designed to elucidate whether some aspects of intravascular ultrasound or pathologic findings could predict a propensity to restenosis. BACKGROUND: Intracoronary ultrasound is a useful technique in guiding and assessing atherectomy. However, there is little information about the characterization of the different types of coronary plaques and the changes observed in them after resection. Furthermore, the follow-up ultrasound appearance of previously treated lesions remains undepicted. METHODS: Fifty-two patients (54 +/- 10 years old) were studied. All were successfully treated by atherectomy with the aid of intracoronary ultrasound guidance. Qualitative and quantitative ultrasound and angiographic variables were derived before and after resection. Quantitative histologic morphometric information was also obtained from the specimens. In 22 patients, a follow-up echoangiographic reevaluation was performed 6 +/- 4 months later. RESULTS: Echogenic plaques had a higher collagen and calcium content, whereas echolucent plaques had an increased level of fibrin, nuclei and lipids. Ultrasound plaque reduction after atherectomy was greater in echolucent (76 +/- 21%) than in echogenic plaques (60 +/- 18%; p < 0.05). That reduction correlated with the weight of the resected material (r = 0.62; p < 0.01). At follow-up study, 13 of 22 patients had angiographic and ultrasound evidence of restenosis. Most recurrent lesions had a stenotic three-layer appearance. The incidence of restenosis of primary lesions treated with atherectomy was higher in echolucent (100%) than in echogenic (33%) plaques. Similarly, a higher proportion of nuclear content in the resected material was observed in patients who developed restenosis (2.1 +/- 0.7%) than in patients who had late success after atherectomy (1.2 +/- 0.6%). CONCLUSIONS: Our findings suggest that echolucent plaques are easier to resect than are echogenic plaques but frequently develop restenosis. In contrast, the resection of echogenic plaques, although often incomplete, is associated with better long-term results.

Atherectomy, Coronary↗