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Biomedical subjects

A Prat

Publications and source records attributed to A Prat.

At least 55 records · Page 3Linked to original sources
PubMed1999

Echocardiographic parameters of the freestyle stentless bioprosthesis in aortic position: the European experience.

The objective of this study was to determine normal Doppler and 2-dimensional characteristics of the Freestyle stentless aortic bioprosthesis. The Freestyle aortic bioprosthesis is a new type of aortic xenograft, and experience is limited. We therefore determined the normal range of echocardiographic and Doppler examinations of this valve. Three hundred thirty-nine consecutive patients with a Freestyle aortic bioprosthesis underwent an echocardiographic and Doppler examination according to a common protocol. Investigations were done within 4 weeks after operation, after 3 to 6 months, and after 1, 2, and 3 years. With a valve size from 19 to 27 mm, mean gradients decreased from 7.9 +/- 5.1 mm Hg at discharge to 5.5 +/- 3. 8 mm Hg after 3 to 6 months (P <.001). Thereafter, gradients remained stable. Effective orifice area 1 year after implantation was 1.59 +/- 0.58 cm(2) for the 21-mm valves, 1.92 +/- 0.74 cm(2) for the 23-mm valves, 2.03 +/- 0.64 cm(2) for the 25-mm valves, and 2.52 +/- 0.72 cm(2) for the 27-mm valves (P <.001). The performance index, the ratio of the measured effective orifice area in the patient divided by the effective orifice area measured in vitro, increased from 67% +/- 20% at discharge to 82% +/- 29% after 1, 2, and 3 years. Performance index was especially very high in the smaller-sized valves. After implantation with the subcoronary technique or root-inclusion technique, small cavities could be seen between the native aortic root and the Freestyle valve. Doppler values were evaluated for the Freestyle stentless porcine bioprostheses in the aortic root. Gradients appear to be close to those measured in native valves over a time period of 3 years.

Adolescent↗
PubMed1999

Acute aortic endocarditis with annular destruction: assessment of surgical treatment with cryopreserved valvular homografts.

BACKGROUND AND AIM OF THE STUDY: Valve ring abscesses in acute infective aortic endocarditis have a low, though not insignificant, prevalence. Surgical treatment with implantation of prosthetic valves may lead to major life-threatening complications, such as recurrent endocarditis and partial or complete prosthetic dislocation. Valvular homografts may offer a higher resistance to recurrent infection and have thus become recognized as an excellent and safe substitute for orthotopic left ventricular outflow reconstruction. METHODS: Between May 1991 and July 1996, 25 patients underwent surgical treatment for aortic endocarditis with annular destruction. Staphylococcus spp. were present in 32% of patients and Streptococcus spp. in 48%. Seven aortic valve replacements (AVR) and 18 aortic root replacements (ARR) were performed using cryopreserved valvular homografts. All grafts were implanted in the subannular position. RESULTS: The overall outcome was good in 23 patients, two died in the early postoperative period. Mean follow up was 38 +/- 18 months (range: 14 to 76 months). No recurrence of endocarditis was detected and no significant alterations of the implants were described. Transvalvular gradients were significantly lower in ARR patients than in AVR patients. CONCLUSIONS: Despite the severity of the tissue damage, cryopreserved homografts, when implanted in the subannular position, constitute a safe and reproducible surgical treatment of aortic endocarditis with annular involvement.

Acute Disease↗
PubMed1999

[Effect of resection of the anterior chordae on cardiac function after surgical correction of mitral valve insufficiency].

The preservation of cardiac function in surgical correction of mitral regurgitation implies partially or totally preserving the subvalvular apparatus. However, the conservation of the whole subvalvular apparatus during mitral valve replacement is technically difficult as the anatomical conditions are not always favourable. In order to determine the consequences of isolated resection of the anterior chordae, the authors studied global and segmental cardiac function by isotopic angiocardiography after mitral valve repair (n = 23) or replacement with conservation of the posterior chordae (n = 16) in 39 patients with isolated, non-ischaemic mitral regurgitation. The left ventricular ejection fraction decreased after valve replacement (64.1 +/- 8.5% to 57.4 +/- 10%, p = 0.01) but not after mitral valve repair (65 +/- 11.3% to 62.1 +/- 12.2%, p = NS). The ejection fractions of segments 4 and 5, corresponding to the zones of insertion of the anterior papillary muscle, decreased after valve replacement compared with repair (segment 4: -9 +/- 13.7 versus +2 +/- 11.3, p = 0.01) (segment 5: -15 +/- 13.2 versus 2 +/- 11.7, p = 0.003). The right ventricular ejection fraction improved after valve repair (40.9 +/- 9.1% to 46.4 +/- 10.1%, p = 0.03), whereas it remained unchanged after valve replacement (42.9 +/- 10.3% to 42.8 +/- 8.6%, p = NS). These results indicate a deleterious effect of isolated resection of the anterior chordae on cardiac function during mitral valve replacement with localised abnormalities of left ventricular function. This study supports the rationale of mitral valve repair or conservation of the anterior and posterior chordae during valve replacement for isolated mitral regurgitation.

Heart Function Tests↗
PubMed1999

Regional capnometry with air-automated tonometry detects circulatory failure earlier than conventional hemodynamics after cardiac surgery.

UNLABELLED: Gastrointestinal automated online air tonometry has been proposed for monitoring gastric perfusion in patients at risk of circulatory failure (CF) after cardiopulmonary bypass. In this study, CF was prospectively defined as the requirement for vasoactive support to maintain mean arterial pressure > or = 70 mm Hg after optimization of preload. Hemodynamic variables--oxygen (O2) delivery (DO2), O2 uptake (Vo2), venous-to-arterial [P(v-a)CO2], gastric-to-arterial [P(r-a)CO2], and gastric-to-end-tidal [P(r-et)CO2]Pco2 gap-were retrospectively compared in 14 patients with or without CF during a 12-hr postbypass period (HO-H12). In contrast to patients without CF (n = 7), in patients with CF (n = 7) increased VO2 was not associated with an increase in DO2. P(r-a)CO2 was larger at H0 in CF patients and was the only variable that differed between the two groups. P(v-a)CO2 did not vary significantly in both groups, whereas P(r-a)CO2 increased to a larger extent from H0 to H12 in patients with CF, suggesting selective gastrointestinal hypoperfusion in this group. P(r-et)CO2 provided comparable information to P(r-a)CO2. Hospital length of stay was 4 days longer (P < 0.05) in patients with CF. Increased P(r-a)CO2 and P(r-et)CO2, as monitored with automated air tonometry, were associated with rapid occurrence of CF and prolonged hospital stay after cardiac surgery. IMPLICATIONS: Regional and automated capnometry may be used noninvasively to identify patients at risk of circulatory failure after cardiopulmonary bypass earlier than with conventional variables.

Capnography↗
PubMed1999

Multiple aneurysmal dysplasia of pulmonary valvular sinuses with congenital focal aplasia of the annulus.

We report the case of a 22-year-old woman in whom a focal aplasia of the pulmonary valve annulus associated with a multiple aneurysmal compensatory dysplasia was found. This patient had been followed since the age of seven years for a congenital asymmetric hypertrophic cardiomyopathy. Cardiac Doppler analysis showed significant pulmonary valvular insufficiency. The patient underwent heart transplant surgery because of total and refractory cardiac insufficiency. Pathological examination of the explanted heart (at the European Homograft Bank) enabled us to describe this valvular malformation. To date, this anomaly has not been described in the literature. Whether it is a malformation discovered fortuitously, or whether it is responsible in part for some of the signs associated with congenital hypertrophic cardiomyopathy is unclear. However, its role might be disclosed by a rigorous investigation of the patient's family.

Adult↗
PubMed1999

Interferon-gamma secretion by peripheral blood T-cell subsets in multiple sclerosis: correlation with disease phase and interferon-beta therapy.

Interferon-gamma (IFN-gamma) is implicated as a participant in the immune effector and regulatory mechanisms considered to mediate the pathogenesis of multiple sclerosis (MS). We have used an intracellular cytokine staining technique to demonstrate that the proportion of ex vivo peripheral blood CD4 and CD8 T-cell subsets expressing IFN-gamma is increased in secondary progressing (SP) MS patients, whereas the values in untreated relapsing-remitting (RR) MS patients are reduced compared with those of controls. Patients treated with interferon-beta (IFN-beta) have an even more significant reduction in the percentage of IFN-gamma-secreting cells. The finding that the number of IFN-gamma-expressing CD8 cells is increased in SPMS patients, a group with reduced functional suppressor activity, and is most significantly reduced by IFN-beta therapy, which increases suppressor activity, indicates that IFN-gamma secretion by CD8 T cells and functional suppressor defects attributed to this cell subset in MS can be dissociated.

Adult↗
PubMed1998

[Assessment of patients' expectations before admission to a tertiary-care center].

BACKGROUND: The customer's final satisfaction with health services depends to some extent, on the relationship between expectancy and perceived quality. Focus groups technique helps in the knowledge of those attributes that patients identified as perceived quality. MATERIAL AND METHODS: The study was performed in the Hospital Clínic i Provincial of Barcelona (HCPB), Spain, by selecting a sample of patient's included in the admission's waiting list (1994) of three common procedures: lens extraction, abdominal hernia repair and routine pregnancy control. The patients were distributed in 12 different semi-structured interview groups (focus groups) and video-taped. From the analysis of those tapes, the main concerns and aspects highlighted by consumers were identified, following a common set of rules: wording, context, internal consistency, precision/vagueness of answers and basic ideas. RESULTS: A total of 106 patients attend the interview. Patients with loss of visual acuity underscore the contribution of quality of life improvement expected from the procedure (technical quality of the surgical procedure, physical improvement and final outcomes). Patient's with abdominal hernia repair highlight the appearance and comfort of hospital setting as the most important item. Pregnant women emphasize the importance of a good follow-up process after delivery, as well as the need for individual services (dignity and intimate). CONCLUSION: The semi-structured interview method (focus group) could be applied in the context of our hospitals, and contribute to improve quality management at our institutions, making effective the patient participation.

Cataract Extraction↗
PubMed1998

Ross operation and mitral homograft for aortic and tricuspid valve endocarditis.

We report here a case of concomitant aortic and tricuspid valve endocarditis occurring in a 26-year-old woman 2 weeks after she had given birth by cesarean delivery. Preoperative transthoracic echocardiography revealed a previously undetected aorta-right atrium fistula, which at operation appeared to be congenital in origin. Surgical treatment consisted of aortic valve replacement with a pulmonary autograft, tricuspid valve replacement with a cryopreserved mitral homograft, and closure of the fistulous communication. The postoperative recovery was uneventful.

Adult↗
PubMed1998

Aortic root replacement with a pulmonary autograft in young adults: medium-term results in 70 patients.

BACKGROUND: Pulmonary autograft aortic valve replacement has been introduced in our institution in selected adult patients in light of the known disadvantages and limitations of conventional prosthetic valves. METHODS: We prospectively evaluated the use of the pulmonary autograft in a series of 70 young adults (31.2+/-8.7 years, range 16 to 49 years) operated on from March 1992 to April 1997 with aortic root replacement only. RESULTS: There were no in-hospital deaths and two noncardiac-related late deaths during follow-up of up to 62 months (mean 33 months). Thromboembolic complications were not observed. One patient required reoperation for infective endocarditis 4.3 years after surgery. Discharge echo-Doppler studies showed normal autograft and allograft valve function. Serial echo-Doppler studies showed no significant progression of aortic insufficiency and no dilatation of the autograft. A severe stenosis of the pulmonary allograft developed in 1 patient. CONCLUSION: Aortic root replacement with a pulmonary autograft, although more complex than conventional prosthetic valve replacement, is a safe, effective, and reproducible procedure in properly selected adult patients. Long-term results remain to be evaluated.

Adolescent↗
PubMed1998

Predictors of restenosis after coronary stent implantation.

OBJECTIVES: We sought to determine predictors of restenosis after coronary stenting (CS) in a consecutive series of patients. BACKGROUND: Although stenting in highly selected patient groups reduces restenosis, the results of stenting in a heterogeneous patient group and the effects of clinical and procedural factors on stent restenosis are currently unclear. METHODS: We analyzed the 6-month angiographic outcome of 500 lesions in 463 consecutive patients undergoing successful CS. Clinical, qualitative and quantitative angiographic variables were correlated with restenosis assessed as both a binary and a continuous variable. RESULTS: Restenosis, defined as the presence of >50% diameter stenosis in the dilated segment, was present in 105 (26%) of the 405 lesions with angiographic follow-up. The mean late lumen loss during the follow-up period was 0.79+/-0.64 mm. Implantation of multiple stents (p < 0.0001) and a high acute gain (p < 0.0002) were independently associated with a higher late lumen loss. In contrast, the use of high inflation pressure (p < 0.02) and Palmaz-Schatz stents (p < 0.005) was independently associated with a lower late lumen loss. When restenosis was defined as a qualitative variable, implantation of multiple stents (p < 0.001), stenosis length (p < 0.01), small reference diameter (p < 0.02) and stent type other than Palmaz-Schatz (p < 0.01) were independent predictors of restenosis. None of the clinical variables tested was associated with restenosis. CONCLUSIONS: Coronary stenting in an unselected patient group is associated with an acceptable restenosis rate. Although some risk factors were identified, the risk of restenosis was not related to most of the variables tested. This suggests that the superiority of CS over balloon angioplasty, in terms of restenosis, might also apply to subgroups of patients that were not included in the recent randomized studies.

Aged↗
PubMed1998

Endovascular treatment of abdominal aneurysmal aortitis in Behçet's disease.

Arterial complications of Behçet's disease are rare and affect mainly the aorta and iliac arteries. Perforation of the arterial wall is the most common lesion, predisposing to false aneurysm or rupture. Open surgical repair is difficult, and anastomotic false aneurysms often occur because of aortic wall fragility. We report here the case of using a bifurcated stent to treat aortoiliac false aneurysms in a 37-year-old patient. Endovascular repair could be an alternative treatment of aneurysmal manifestations in Behçet's disease.

Adult↗
PubMed1998

Can cerebrovascular microemboli induce cognitive impairment in patients with prosthetic heart valves?

Doppler ultrasonography can be used to detect the presence of emboli in the cerebral arterial circulation. Emboli can be produced by different sources and can be of different nature: solid elements as thrombi, platelet aggregates or atheromatous material, or gaseous when they are produced during the decompression phase of diving or during extracorporeal circulation (ECC) procedures. A more recent source of emboli has been found in the mechanical prostheic heart valves (MHV). The emboli generated by MHV are likely of gaseous nature and are found in the middle cerebral artery blood flow at a variable rate, where they are detected by transcranial Doppler sonography. The mechanism of production of these microbubbles may be related to the rapid leaflet motion especially at closure when very high local pressure gradients appear, which may be able to provoke a release of the disolved blood gas. Solid element emboli constitute a major cause of cerebrovascular disease and particularly stroke. Conversely, gaseous emboli coming from ECC or MHV are considered as clinically silent. Nevertheless, cognitive alterations have been reported after ECC. As the MHV carriers are chronically submitted to embolic events, it can be assumed that cognitive impairments may occur also in these patients. A preliminary study was designed to inpatients attention and memory in patients with normally functioning MHV and microemboli, with biological prosthesis and in normal subjects. In the two groups of patients, episodic memory was significantly altered relatively to the control group. In the MHV carriers group, a significant decrease in working memory performance was observed relatively to the two other groups. These results confirm a long term effect of the microembolization occuring during ECC and point out the effect of the chronic exposition to microemboli.

Bioprosthesis↗
PubMed1998

Combined tracheal resection and aortic valve replacement with a cryopreserved aortic valve allograft.

A 69-year-old patient presented with an association of tracheal squamous cell carcinoma and severe aortic valve stenosis. As there was no evidence of metastatic spread a potentially curative resection could be considered. The patient underwent tracheal resection and aortic valve replacement in a one-stage procedure. In light of the potential risk of infection to a prosthetic valve, a cryopreserved aortic valve homograft was implanted. The patient made a full recovery and is doing well after 2 years of follow-up.

Aged↗
PubMed1998

Early and late results and the effects on pulmonary arteries of balloon dilatation of the right ventricular outflow tract in tetralogy of Fallot.

BACKGROUND: Balloon dilatation of the pulmonary valve remains controversial as a palliative procedure in tetralogy of Fallot. AIMS: To determine the clinical outcome, growth of the pulmonary vascular tree and findings at surgery of balloon dilatation of the pulmonary valve performed as a palliation in infants with tetralogy of Fallot. METHODS AND RESULTS: Thirty-three severely cyanosed infants (mean age of 3 months for the whole population, including seven neonates) underwent this procedure from June 1990 to January 1997. After balloon dilatation, systemic oxygen saturation increased from a mean value of 76 +/- 9% to 88 +/- 7% (P < 0.001). The procedure was accomplished without complications. Four patients had recurrent hypoxic spells after dilatation leading to surgical repair within 30 days of dilatation (three modified Blalock-Taussig shunts and one complete repair). A control study was performed at a mean of 6.1 +/- 4.5 months after dilatation in 16 patients to establish growth of the pulmonary vascular tree (repeat catheterization in nine patients and surgical pulmonary annulus calibration in seven). The pulmonary annulus increased from a mean Z score of -4.1 +/- 0.9 SD to -2.5 +/- 1.1 SD (P < 0.001). Z score for the right pulmonary artery from -3.0 +/- 0.6 SD to -1.9 +/- 1.2 SD (P = 0.007) and the Z score for the left pulmonary artery from -2.7 +/- 0.7 SD to -1.6 +/- 1.3 SD (P = 0.021). At late follow-up (mean of 9 months after dilatation, range 3 to 54 months), 28 patients underwent complete repair. Trans-annular patching was required in 43% of patients. Four post-operative deaths were observed, none dilatation related. CONCLUSION: Balloon dilatation of the pulmonary valve is an effective and safe palliation in tetralogy of Fallot. It promotes growth of the pulmonary vascular tree, reducing the need for trans-annular patching and is recommended in symptomatic infants of very young age, with a small pulmonary annulus (Z value below -4 SD) and associated cardiac anomaly.

Blood Flow Velocity↗
PubMed1998

Microemboli in cerebral circulation and alteration of cognitive abilities in patients with mechanical prosthetic heart valves.

BACKGROUND AND PURPOSE: It has been shown previously that cerebral microemboli may occur frequently in patients with a normal mechanical heart valve (MHV) without prior history of stroke. Some arguments strongly suggest that these microemboli have a gaseous origin. In other circumstances such as extracorporeal circulation or decompression in divers, it has been demonstrated that cerebral microbubbles could lead to some deterioration in cognitive functions. Therefore, we have studied attention and memory, which are among the most impaired cognitive functions as demonstrated in previous studies, in patients with an MHV. METHODS: Three groups of 12 volunteers each were composed of patients with an MHV and embolic signals in the cerebral circulation (group 1), patients with biological prostheses (group 2), and healthy subjects (group 3). Groups were carefully matched for age and verbal intellectual abilities. For each group, a transcranial Doppler examination was performed and a set of cognitive tests assessing sustained and selective attention and episodic and working memory was administered. RESULTS: The mean embolic rate was 29 per hour in patients with an MHV. No embolus was detected in the other 2 groups. Episodic memory was significantly modified in both groups 1 and 2 compared with the control group for tasks that required high-processing resources. Working memory performance was significantly decreased in MHV patients. No between-groups differences were observed for the other parameters. CONCLUSIONS: Alteration of episodic memory can be attributed to a long-term effect of the surgical procedure. Deterioration of working memory can be related to the presence of cerebral microemboli in MHV patients.

Aged↗
PubMed1998

Mechanical modifications to human pericardium after a brief immersion in 0.625% glutaraldehyde.

BACKGROUND AND AIMS OF THE STUDY: The use of human pericardium pretreated for 10 min with 0.625% glutaraldehyde (GLUT) in valvular repair or intracardiac reconstruction has produced good results. However, to date, no investigations have been made to determine the mechanical changes that occur in the tissue following such pretreatment. METHODS: Human pericardial samples were harvested from 25 patients and immersed in GLUT for increasing times (5, 10, 30, 60 min and 6 months). Either untreated human pericardium or bovine pericardium treated for six months with GLUT served as controls. Tensile tests were performed with a uniaxial load machine and a pulsative bench. Fatigue testing was for 14 days; each sample was tested at 1,200 cycles/min at a controlled pressure of 90-120 mmHg. RESULTS: Untreated tissue thickness was 0.44+/-0.16 mm, but after six months GLUT treatment it was 0.53+/-0.15 mm (p<0.001). There was a 13.7% shrinkage of tissue after six months immersion. Strain was significantly greater in treated tissue than in untreated tissue, while stiffness decreased with the duration of GLUT immersion. Young's modulus was significantly lower after six months GLUT treatment (0.26+/-0.06 MPa) compared with untreated, and 5-, 10- and 30-min GLUT treatment (0.32+/-0.15, 0.35+/-0.09, 0.32+/-0.09 and 0.36+/-0.10 MPa (p<0.05)), respectively. Creep was greater after six months GLUT treatment (0.5+/-0.03%) than in untreated and 10-, 30- and 60-min treatments (0.3+/-0.50, 0.27+/-0.01, 0.27+/-0.02, 0.3+/-0.01% (p<0.05)), respectively. Ultimate tensile stress (UTS) was greater in 10-min treated pericardium than in untreated tissue: 38.46+/-11.75 versus 22.17+/-8.30 MPa (p<0.05) respectively. Strain at rupture was greater in the 6-month group (30.62+/-2.54%) than for untreated and 10-, 30- and 60-min GLUT immersion 16.3+/-0.73, 21.85+/-0.75, 20.12+/-1.04 and 18.87+/-0.86% (p<0.05), respectively. Fatigue testing showed an increased length after five and 10 min, and six months, with a lengthening of 14.66, 12.53, 7.66%, respectively compared with 3.5% for untreated tissue (p<0.05). There were three failures in the untreated group (n = 5), none in the 5- and 10-min groups, and one in the 6-month group (p<0.05). CONCLUSION: Brief immersion of human pericardial tissue in 0.625% glutaraldehyde reduces the tissue's stiffness and improves its durability for use in cardiac surgery.

Biomechanical Phenomena↗
PubMed1997

Human and rat testis express two mRNA species encoding variants of NRD convertase, a metalloendopeptidase of the insulinase family.

Rat testis NRD convertase (EC 3.4.24.61) is a Zn2+-dependent endopeptidase that cleaves, in vitro, peptide substrates at the N-terminus of Arg residues in dibasic sites. This putative processing enzyme of the insulinase family of metallopeptidases exhibits a significant degree of similarity to insulinase and two yeast processing enzymes, Axl1 and Ste23. We report the cloning of two human testis cDNA species encoding isoforms of NRD convertase, hNRD1 and hNRD2. Whereas the hNRD1 transcript (3.7 kb) is equivalent to the previously characterized rat cDNA (rNRD1), hNRD2 and rNRD2 are 3.9 kb novel forms containing a nucleotide insertion encoding a 68-residue segment. This motif, which is inserted N-terminal of the Zn2+-binding site, HXXEH, is contained within the most conserved region among the insulinase family members. Analysis of the deduced primary sequences revealed 92% identity between rat and human orthologues. The human gene encoding NRD convertase was localized to chromosome 1p32.1-p32.2. Whereas NRD convertase is mostly expressed in testis and in 24 cell lines, low mRNA levels were detected in most of the 27 other tissues tested.

Amino Acid Sequence↗