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Biomedical subjects

A Aris

Publications and source records attributed to A Aris.

At least 19 recordsLinked to original sources
PubMed2002

Dentine hypersensitivity in subjects recruited for clinical trials: clinical evaluation, prevalence and intra-oral distribution.

Relatively few studies have reported on the frequency, distribution and severity of dentine hypersensitivity (DH) in subjects recruited for clinical trials of desensitizing agents. Potential subjects (n= 48 M, 81 F, mean age 35.1 years) for inclusion into such a study were screened to determine the extent of the problem. 117 subjects (41 M, 76 F) mean age 24.9 years were clinically examined. Evaluation by questionnaire indicated that the prevalence of DH was proportionately higher in the 20-29.9 years (34.9%), and 30-39.9 years groups (33.3%), respectively. Sensitivity to cold was the main presenting symptom. Tactile (probe) and cold air (dental air syringe) stimuli were used to clinically evaluate DH. Of the teeth eligible for evaluation 1561/3136 (49.8%) responded to either one or both of the test stimuli; 274/3136 (8.7%) responded to tactile only stimulation, 779/3136 (24.8%) to thermal only stimulation and 508/3136 (16.2%) to both tactile and thermal stimulation. Of those teeth responding to the stimuli, 477 (30.6%) were premolars, 437 (28%) incisors, 415 (26.8%) molars and 232 (14.9%) canines. The results agree with those of previously reported studies in that DH is most frequently observed on premolars and that proportionately more teeth are sensitive to evaporative than to tactile stimulation. Furthermore it would appear from the results of the study that tactile is less effective than thermal/evaporative stimulation in the evaluation of DH.

Adult↗
PubMed2002

Influence of varying reacting conditions in the degradation of azo dye using immobilized TiO2 photocatalyst.

In Malaysia, most colored wastewater from dyeing factories is discharged to the environment causing serious problems. In this paper the influence of several reacting conditions, i.e. H2O2, pH, Ultraviolet (UV) intensity and dye concentration, on the performance of the immobilized system is discussed. The pH of the solution was varied from 3 to 11 while H2O2 concentration tested was from 10(-4) M to 5 x 10(-2) M. UV was tested at 365 nm and 254 nm, while dye concentration ranged from 2.5 x 10(-4) M to 10(-3) M. The influence of the reacting conditions was assessed based on absorbance. Using an OG concentration of 10(-3) M, the degradation increases from 17.8% to 49.7%. Optimum concentration of H2O2 was found to be 5 x 10(-3) M for degradation. Increasing the intensity of the UV light via shorter light wavelength also improves the performance of the system. Increasing the concentration of the dye reduces the overall performance of the system. Using the dye concentration of 2.5 x 10(-4) M (H2O2 = 10(-2) M, lambda = 254 nm, pH = 11), gives a degradation of 93.2%. At dye concentration of 10(-3) M, the performance was reduced to 53.1%.

Azo Compounds↗
PubMed2000

Multiple intracardiac lesions after blunt chest trauma.

Closed chest trauma can cause rupture of intracardiac structures. We report the case of a 17-year-old boy whose chest was trodden by a horse. He sustained rupture of tricuspid and aortic valve leaflets and rupture of the interventricular septum. He underwent surgical repair of these lesions, but aortic insufficiency developed 2 years later and the aortic valve was replaced with a mechanical prosthesis.

Adolescent↗
PubMed1999

Reversed "C" ministernotomy for aortic valve replacement.

The technique of aortic valve replacement through a reversed "C" sternotomy incision is described. The sternal incision extends between the second and the fifth intercostal space and provides excellent exposure of the ascending aorta, the aortic root, and the right atrial appendage. The procedure can be performed with standard cannulation for cardiopulmonary bypass and conventional surgical instruments.

Heart Valve Prosthesis Implantation↗
PubMed1999

Repair of aortic coarctation in patients more than 50 years of age.

BACKGROUND: Most patients with uncorrected coarctation of the aorta die before reaching age 50 years. In those who survive, the beneficial effect of surgical repair on systolic hypertension has been questioned. METHODS: Surgical repair of aortic coarctation was performed in 8 patients aged 51 to 73 years (mean, 58+/-9 years). Preoperative mean systolic pressure was 185+/-34 mm Hg and systolic gradient, 70+/-11 mm Hg. In addition, 3 patients had significant coronary artery disease. Severe calcification of the aortic arch and left subclavian artery was found in 3 patients. The surgical technique involved bypass of the coarctation with a Dacron tube graft (16 or 18 mm) in all patients. One patient underwent concomitant coronary artery bypass grafting. RESULTS: There were no operative or late deaths during a mean follow-up of 4.3 years. Mean systolic blood pressure decreased significantly in the postoperative period to 128+/-16 mm Hg (p < 0.001). At the last visit, systolic blood pressure was a mean of 127+/-9 mm Hg. Five patients were not taking antihypertensive medication. CONCLUSIONS: Surgical repair of aortic coarctation in patients more than 50 years of age with a Dacron tube bypass graft reduces systolic hypertension and the need of antihypertensive medication.

Aged↗
PubMed1999

Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study.

BACKGROUND: Minimally invasive aortic valve replacement reduces surgical trauma and, supposedly, postoperative pain, blood loss, and length of stay. A prospective, randomized study was designed to prove these theoretical advantages. METHODS: Forty patients undergoing isolated, elective aortic valve replacement were randomized into two equal groups. Patients in group M underwent aortic valve replacement through a ministernotomy (reversed L or reversed C). In group S, a median sternotomy was used. The anesthetic and surgical protocol was identical for both groups. Pain was evaluated on a daily basis. Pulmonary function tests were performed preoperatively and before hospital discharge in all patients. RESULTS: There were two deaths in each group. Cross-clamp time was longer in group M: 70 +/- 19 minutes versus 51 +/- 13 minutes in group S (p = 0.005). There were no statistically significant differences between groups M and S in pump time (95 +/- 20 minutes versus 83 +/- 19 minutes), extubation time (9.9 hours in both groups), chest drainage (479 +/- 274 mL/L 24 hours versus 355 +/- 159 mL/24 hours), transfusion requirements (27% in both groups), pain evaluation (1.34 +/- 1.3 versus 2.15 +/- 1.5), length of stay (6.2 +/- 2.3 days versus 6.3 +/- 2.5 days), and cosmetic appraisal. Forced vital capacity decreased 26% from preoperative reference values in group M and 33% in group S (p = not significant). Forced expiratory volume in 1 second decreased 22% and 35%, respectively (p = not significant). CONCLUSIONS: This study has failed to prove the theoretical advantages of minimally invasive aortic valve replacement. With this technique, cross-clamp time is longer than with a median sternotomy.

Adult↗
PubMed1999

Technique of mitral valve replacement with the Monostrut prosthesis preserving the posterior leaflet.

BACKGROUND AND AIM OF THE STUDY: Techniques of mitral valve replacement with leaflet and chordal preservation normally involve the use of a bioprosthesis or bileaflet valve to reduce the risk of obstruction of the prosthesis by the retained subvalvular apparatus. METHODS: The technique of mitral valve replacement with the Monostrut prosthesis and with preservation of the posterior leaflet is described. The stitches are placed in such a manner that the posterior leaflet is folded under the posterior aspect of the prosthetic ring. RESULTS AND CONCLUSIONS: The technique allows safe implantation of the Monostrut valve. The excellent performance of this prosthesis can be therefore combined with the beneficial effects of chordal preservation on left ventricular function.

Heart Valve Prosthesis↗
PubMed1999

Pulmonary function following aortic valve replacement: a comparison between ministernotomy and median sternotomy.

BACKGROUND AND AIM OF THE STUDY: Minimally invasive aortic valve replacement (AVR) has several theoretical advantages over standard median sternotomy, but the effects of these techniques on postoperative pulmonary function have not been determined. METHODS: Twenty-six patients undergoing AVR through either a ministernotomy (group M; n = 12) or a median sternotomy (group S; n = 14) underwent pulmonary function tests. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), PaO2 and PaCO2 were determined preoperatively and before hospital discharge (at a mean of five days). Data regarding time to extubation, degree of pain and opening of the pleura were collected prospectively. Both groups had similar preoperative characteristics. RESULTS: There was a significant decrease in FVC, FEVJ, PaO2 and PaCO2 during the postoperative period in all patients, though differences between the groups were not significant. Patients in group M referred less pain than those in group S. In this group, the fall in FVC and FEV1 correlated with the degree of pain, while preoperative FVC correlated with early extubation. Pleurotomy did not affect pulmonary function or pain. CONCLUSION: FVC, FEV1, PaO2 and PaCO2 are reduced significantly following AVR, but a minimally invasive approach does not prevent postoperative pulmonary dysfunction.

Aged↗
PubMed1997

Francisco Romero, the first heart surgeon.

Francisco Romero, a Catalonian physician, became the first heart surgeon when he performed an open pericardiostomy to treat a pericardial effusion in 1801. He presented his work at the Society of the School of Medicine in Paris in 1815, but the procedure was considered too aggressive and his work was silenced for many years. Proper credit should be given to Romero as the first man who directly approached the heart by incising the pericardium.

Cardiac Surgical Procedures↗
PubMed1996

As originally published in 1988: Long-term results of mitral valve surgery in patients with severe pulmonary hypertension. Updated in 1996.

Mitral valve surgery was performed in 88 patients with severe pulmonary hypertension (average systolic pulmonary artery pressure, 94.7 +/- 22 mm Hg; range, 70-180 mm Hg) over a 10-year period. Sixty-four patients (73%) were in New York Heart Association Functional Class III or IV. There were 64 valve replacements and 24 open mitral commissurotomies. Operative mortality was 5.6% (5 patients) and was not related to the degree of pulmonary hypertension, surgical procedure performed, or type of valve lesion. A 100% follow-up was obtained, ranging from nine months to 10 years, with a mean of 44 months. Six late cardiac deaths (7.2%) occurred, 5 in patients with valve replacement and 1 in a patient who underwent a commissurotomy. Actuarial survival was 86 +/- 3% at five years and 83 +/- 4% at 10 years. Fourteen patients underwent right ventricular catheterization a mean of 24 months following operation. Systolic pulmonary artery pressure had decreased from a mean preoperative value of 101 +/- 22 to 40.5 +/- 7 mm Hg (p < 0.001). Cardiac index increased by 55% of the preoperative values. Functional status improved markedly; 71 survivors (93%) were in New York Heart Association Class I or II. These results indicate that, in patients with mitral valve lesions and severe pulmonary hypertension, (1) surgical procedures can be performed with an acceptable operative mortality; (2) excellent long-term survival and functional results can be obtained; and (3) pulmonary hypertension decreases significantly after operation. Patients with mitral valve disease may benefit from surgical treatment regardless of the degree of pulmonary hypertension.

Heart Valve Diseases↗
PubMed1996

The Spanish Monostrut Study Group: a ten-year experience with 8,599 implants.

BACKGROUND: The Monostrut valve is a pyrolytic carbon, tilting-disc prosthesis with no welds. After the first implantation in Spain in May 1983, the Spanish Monostrut Study Group was established to evaluate prospectively the performance of the valve using uniform protocols. METHODS: During a 10-year period, 8,599 Monostrut valves were implanted in 7,317 patients in 22 centers. Mean age was 53.3 +/- 11 years. Of the total group, 3,229 underwent aortic valve replacement, 2,806 had mitral valve replacement, and 1,282 had double valve replacement. Follow-up was 96% complete, with a mean period of 4.3 years and a total of 29,155 patient-years. RESULTS: The operative mortality rate was 7.2%. The 10-year probability of freedom from valve-related complications and linearized rates (event/100 patient-years in parentheses) were as follows: structural deterioration, 100% (0); nonstructural dysfunction, 96% +/- 0.5% (0.51); thromboembolism, 82.9% +/- 1.5% (1.32); anticoagulant-related hemorrhage, 87.6% +/- 1.4% (0.98); and prosthetic valve endocarditis, 96.1% +/- 0.5% (0.48). There were five obstructive valve thromboses (0.017/100 patient-years). Actuarial freedom from reoperation was 95% +/- 0.5% at 10 years. Actuarial freedom from all valve-related morbidity was 70.2% +/- 1.6%; freedom from all valve-related morbidity and mortality (including operative and sudden deaths) was 62.6% +/- 2% (70.1% +/- 2% for aortic valve replacement, 56.9% +/- 2% for mitral valve replacement, and 59.8% +/- 3% for double valve replacement; p < 0.0001). Clinically, 5,988 patients (94%) are in New York Heart Association class I-II. CONCLUSIONS: The Monostrut valve has shown no structural failures and a low rate of valve-related complications over a 10-year period in a large patient population.

Actuarial Analysis↗
PubMed1996

The 20 mm Medtronic Hall prosthesis in the small aortic root.

BACKGROUND AND AIMS OF THE STUDY: The choice of prosthesis becomes crucial in the narrow aortic annulus. The 20 mm Medtronic Hall valve has a reduced sewing ring that fits in an annulus where only a 19 mm valve would fit. This study assesses the hemodynamic performance of this prosthesis at rest and at exercise, and compares it with two 19 mm mechanical prostheses. MATERIALS AND METHODS: Forty-two patients were studied by Doppler echocardiography, a mean of 34 months following surgery. Twenty-six had a 19 mm prosthesis implanted (12 standard St. Jude Medical and 14 Monostrut valves) and 16 had a 20 mm Medtronic Hall. Parameters studied were peak velocity and transvalvular gradient, both at rest and at exercise, effective orifice area and valve index. RESULTS: No differences were found between the two 19 mm valves, but when compared with the Medtronic Hall valve at rest, this valve showed significantly lower peak velocity and gradient (2.9 vs. 3.3 m/sec, p < 0.01, and 17 vs. 23 mmHg, p < 0.003, respectively) and higher effective orifice area and valve index (1.3 vs. 1.0 cm2, p < 0.01 and 0.81 vs. 0.62 cm2, p < 0.006, respectively). There were also significant differences under exercise. CONCLUSIONS: The 20 mm Medtronic Hall prosthesis shows a significantly better hemodynamic performance, both at rest and under exercise, than other, 19 mm mechanical prostheses and represents a superior choice in valve replacement with a small aortic root.

Aged↗