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Biomedical subjects

C M Duran

Publications and source records attributed to C M Duran.

At least 37 records · Page 2Linked to original sources
PubMed1998

An in vitro study of the correlation between aortic valve diameter and mitral intertrigonal distance: a simple method to select the correct mitral annuloplasty ring size.

BACKGROUND AND AIMS OF THE STUDY: The application of the flexible Duran mitral annuloplasty ring in the treatment of various mitral valvular diseases is a physiologically appealing method of surgical repair. However, accurate identification of the trigonal structures, which is crucial in selecting the proper ring size, cannot always be made with certainty. A method is proposed to calculate the intertrigonal distance (ITD) from the aortic diameter. METHODS: Using digital calipers, the linear intertrigonal distance was measured in human homograft (n = 10) and sheep (n = 10) aortic root specimens. The aortic diameter was obtained from the circumference of the pressurized aortic root. A conversion factor was acquired for each specimen by dividing the aortic diameter with the measured ITD. A single constant conversion factor, which closely approximated the mean of the conversion factors in both groups, was then applied broadly to derive the ITD by calculation from the aortic diameter, which is known. The validity of using this constant conversion factor was tested by comparing the degree of variation of the calculated ITD from the direct measurements of the ITD. RESULTS: The mean of the conversion factors was 0.79 and 0.80 in the human and the sheep roots, respectively. The value 0.80 was used as the constant conversion factor in both groups for calculating the ITD. A paired comparison t-test in each group showed the difference between the calculated intertrigonal distance and the direct measurements of the ITD to be insignificant, validating the use of 0.80 as a constant conversion factor. CONCLUSIONS: The results of the study suggest that the conversion factor of 0.80 can be reliably used to obtain a calculated value of the intertrigonal distance; this method has the potential to aid the surgeon in determining the intertrigonal distance and the proper ring size.

Animals↗
PubMed1996

The sheep as an animal model for heart valve research.

The first test used to assess new heart valve prostheses and devices is to implant them in a medium-sized animal. This is a costly piece of research and it is important to select the most appropriate animal. The authors feel that the sheep is an appropriate animal model for heart valve research and describe their experience in this area. It is hoped that the detailed description provided will be useful to any other group contemplating similar studies.

Animals↗
PubMed1996

Immediate and long-term effect of mitral balloon valvotomy on severe pulmonary hypertension in patients with mitral stenosis.

The pulmonary vascular hemodynamics were studied in 21 patients with severe mitral stenosis and severe pulmonary hypertension. Hemodynamic data were obtained before and immediately after mitral balloon valvotomy (MBV) and at follow-up 7 to 14 months (mean 12 months) later by repeat catheterization. The mean pulmonary capillary wedge pressure (PCW) decreased from 27 +/- 5 to 15 +/- 4 mm Hg (p < 0.001). The mean mitral valve gradient (MVG) decreased from 18 +/- 4 to 6 +/- 2 mm Hg (p < 0.001). Mitral valve area (MVA) increased from 0.6 +/- 0.1 to 1.5 +/- 0.3 cm2 (p < 0.02). Cardiac index increased from 2.2 +/- 0.3 to 2.6 to 0.5 L/min/m2 (p < 0.02). The pulmonary artery systolic pressure decreased from 65 +/- 13 to 50 +/- 13 mm Hg (p < 0.001), and no significant change was seen in pulmonary vascular resistance (PVR) immediately after MBV from 461 +/- 149 to 401 +/- 227 dynes/sec/cm(-5) (p = 0.02). At follow-up the MVA increased from 1.5 +/- 0.3 to 1.7 +/- 0.3 cm2 (p < 0.02). Cardiac index increased further to 3 +/- 0.4 L/min/m2 (p < 0.02). MVG and PCW pressure remained the same. The pulmonary artery systolic pressure decreased further to 38 +/- 9 mm Hg (p < 0.02). PVR decreased significantly to 212 +/- 99 dynes/sec/cm(-5) (p < 0.02). We concluded that the pulmonary artery pressure decreased without normalizing immediately after MBV and normalized in patients with optimal results from mitral balloon valvotomy 7 to 14 months later. Insignificant change in PVR was seen immediately after MBV and markedly decreased or normalized at late follow-up in patients with optimal result from MBV.

Adolescent↗
PubMed1996

Clinical and echocardiographic follow-up after aortic valve reconstruction with bovine or autologous pericardium.

Eighty-six patients, mean age 29 +/- 15 years, underwent aortic valve reconstruction with bovine or autologous pericardial tissue. Mean clinical follow-up was 35 months. Echocardiographic data were assessed in 65 patients with follow-up > or = 6 months. There were two in-hospital and three late deaths. Warfarin was not given, and no thromboembolic events occurred. Five (6%) patients needed reoperation because of severe aortic regurgitation. Peak aortic valve gradients remained low (26 +/- 14 mm Hg for the bovine group and 16 +/- 16 mm Hg for the autologous group). One patient is awaiting surgery for aortic stenosis after 76 months. Leaflet thickening at latest follow-up was marked in six (9%) patients. Left ventricular dimensions normalized postoperatively and showed only insignificant increase during follow-up. This technique is a promising alternative to valve prosthesis in selected patients; however, longer follow-up is necessary to assess long-term results.

Adolescent↗
PubMed1996

Influence of cooling on mesenteric vascular reactivity.

OBJECTIVES: Cardiopulmonary bypass has been shown to cause hypoperfusion of certain vascular beds leading to multiple system organ failure. It has been reported that the gut may be an important trigger. The underlying mechanism is not fully known, but vascular changes, particularly those due to cooling, could play a role. METHODS: We examined the effect of cooling (28 degrees C) and subsequent rewarming (37 degrees C) on the vascular reactivity of the rabbit mesenteric artery and abdominal aorta to a range of vasoactive substances using an in vitro organ bath apparatus. Cumulative concentration-responses of the agonists (noradrenaline, histamine, dopamine and potassium chloride) were examined at 37 degrees C, then repeated at 28 degrees C and then subsequently repeated after rewarming to 37 degrees C. RESULTS: All agonists were capable of inducing a constrictor response on the mesenteric artery and abdominal aorta. The results represent means +/- SEM. There was an increase in potency of noradrenaline at the lower temperature [from 5.6 +/- 0.1 (37 degrees C) to 6.0 +/- 0.1 (28 degrees C); Bonferroni-corrected P < 0.05; n = 10], which returned to normal [5.6 +/- 0.1 (37 degrees C)] following rewarming in the mesenteric artery. In contrast, there was a decrease in potency of noradrenaline in the aorta on cooling [6.5 +/- 0.1 (37 degrees C) to 6.2 +/- 0.1 (28 degrees C); Bonferroni-corrected P < 0.05; n = 8]. Neither histamine or dopamine showed any difference in potency at 28 degrees C or at 37 degrees C following rewarming in the mesenteric artery or aorta. There was no difference in the efficacy of the response of the mesenteric artery to noradrenaline as indicated by the maximum responses. However, the response to the highest dose of dopamine was increased on rewarming to 37 degrees C compared to control responses at 37 degrees C before cooling in the aorta [7.23 +/- 1.48 g vs 3.6 +/- 0.6 g; Bonferroni-corrected P < 0.05; n = 14]. Histamine contractions were attenuated at 28 degrees C and following rewarming to 37 degrees C in the mesenteric artery [5.5 +/- 0.5 g (37 degrees C) vs 2.2 +/- 0.2 g (28 degrees C); Bonferroni-corrected P < 0.05; n = 18], [5.5 +/- 0.5 g (37 degrees C) vs 2.32 +/- 0.5 g (37 degrees C rewarming); Bonferroni-corrected P < 0.05; n = 18]. CONCLUSIONS: We conclude that cooling elicits a heterogeneous responsiveness of the rabbit mesenteric artery and abdominal aorta to noradrenaline and dopamine which could have important implications for blood flow to mesenteric vascular beds during hypothermic cardiopulmonary bypass.

Adrenergic alpha-Agonists↗
PubMed1996

Critical role of the sinuses of Valsalva in the durability of valved conduits.

BACKGROUND AND AIMS OF THE STUDY: Most work in search of an ideal extracardiac valved conduit has assumed that the type of tissue used for construction is the determining factor for its behavior and durability. The excellent results of our study with a valved conduit incorporating sinuses of Valsalva and made of autologous pericardium showed that the design plays a crucial role in addition to the type of material. MATERIALS AND METHODS: We report the experimental results of three different pericardial sinus bearing valved conduits made of 0.5% glutaraldehyde treated autologous pericardium (Group 1), dye mediated photooxidized bovine pericardium (Group 2), and glutaraldehyde treated bovine pericardium (Group 3) implanted in the right ventricular outflow tract of sheep. Groups 1, 2 and 3 had 11, 11 and four animals available for assessment out of 12, 18 and six implantations respectively. The valved conduits were explanted at varying intervals between one and 11 months. The conduit function was assessed with hemodynamic, echocardiographic and Doppler studies both at the time of implantation and sacrifice. The explanted conduit was studied macroscopically and subjected to histopathologic examination. RESULTS: The hemodynamic and echocardiographic studies at implantation showed very satisfactory results in all three groups. At the time of sacrifice, Group 1 showed consistently good results. In a significant number of animals in Groups 2 and 3, one, two or even three cusps had become adherent to the conduit wall, resulting in severe regurgitation. The sinuses were well preserved in Group 1, while they were less prominent in Group 2 and least in Group 3. Histopathologically, the three groups basically showed the same feature, a process of fibrocellular proliferation resulting in thickening. In this study the adhesion of the cusps to the sinus wall was related to the degree of prominence of the sinuses of Valsalva, which in turn depended on the ability to shape the pericardium at the time of construction of the valved conduit. CONCLUSIONS: This study stresses the importance of the sinuses in the behavior of the semilunar valve leaflets.

Animals↗
PubMed1996

Surgery for rheumatic mitral regurgitation in patients below twenty years of age. An analysis of failures.

BACKGROUND AND AIM OF THE STUDY: Mitral valve repair is less stable in rheumatic than in degenerative disease. This failure rate is inversely related to the age of the patient. Based on our clinical experience, we selected the group of patients with the worst results for this study: (i) rheumatic, (ii) age 20 or under, (iii) pure mitral regurgitation (MR), and, (iv) no aortic disease. MATERIALS AND METHODS: Between 1988 and 1995, 83 consecutive patients complied with these characteristics. No patient was excluded. Replacement (MVR) was performed in 26 and repair (MRp) in 57 (69%). RESULTS: There was one hospital death (1%) with an actuarial survival at 48 months of 74.8% +/- 19% for MVR and of 97.9% +/- 2.1% at 78 months for MRp. There were no thromboembolic events. Reoperation was required in one MVR (4%) and in 21 MRp (37%), within same admission in six, within three months in eight, under one year in three, and beyond in four cases. Severe MR appeared in five further cases. No statistical difference was found between the preoperative clinical data, operative findings and surgical maneuvers of those patients with successful and unsuccessful repair. The rate of failure was similar after Kay (14/29) and Duran (12/28) annuloplasty. All patients showed a rapid decrease in left ventricular dimensions. Early failures showed elongation of previously shortened chordae at reoperation, together with more reduction in systolic dimension than the other groups. Late failures were more related to progression of the rheumatic process. No clear relationship between rheumatic activity and failure rate was found. CONCLUSION: Rheumatic mitral regurgitation in the young remains a serious problem. The treatment of this frequent pathology in the developing countries needs a new approach based on the knowledge that it starts at the annulus. Earlier surgery at this level might prevent its further progression, avoiding the problems of secondary chordal elongation.

Adolescent↗
PubMed1995

Unstented semilunar homograft replacement of tricuspid valve in Ebstein's malformation.

Tricuspid valve pathology in Ebstein's malformation requires replacement when it is not possible to repair or reconstruct this valve. In smaller children, in whom the right-sided atrioventricular valve is severely dysplastic and right ventricular volume is prohibitive, prosthetic replacement is not always possible. We report here on 3 patients who underwent stentless semilunar homograft replacement (top-hat procedure) of tricuspid valve for Ebstein's anomaly with good short-term outcome. This provides an attractive alternative in the management of a certain difficult subset of patients, avoids long term anticoagulation and probably is more durable.

Child↗
PubMed1995

Aortic translocation for D-TGA associated with LVOTO and VSD.

Aortic translocation is a useful surgical option in certain difficult subsets of transposition of great arteries with ventricular septal defect and left ventricular outflow tract obstruction. We report here the use of this technique with pulmonary homograft reconstruction of right ventricular pulmonary artery continuity in a child with transposition of the great arteries, left ventricular outflow tract obstruction, and restrictive ventricular septal defect.

Aorta↗
PubMed1995

From aortic cusp extension to valve replacement with stentless pericardium.

Between 1988 and 1994, 82 consecutive patients (median age 24 years) underwent reconstruction of the aortic valve with glutaraldehyde-treated pericardium. Simultaneously, 29 of 30 mitral valves were repaired. The first 27 patients underwent resection of the free edges and suture of a single strip of bovine pericardium. Transient ischemic changes suggested the need for a change in technique. The subsequent 55 patients underwent total valve reconstruction with an autologous pericardium fixed with glutaraldehyde in the appropriate shape and size according to the patient's aortic annulus. There were one in-hospital and three late deaths. No patient received anticoagulation, and no embolic events were detected. Nine patients required reoperation as a result of failure of mitral valve repair in 4 and severe aortic regurgitation in 5 (endocarditis [n = 2], commissural tear [n = 1], root dilation [n = 1], calcification of one bovine cusp [n = 1] at 58 months). There were no reoperative deaths. Complete linear echocardiographic follow-up of these patients showed low gradients, valve competence, and no progressive deterioration. No difference between techniques was detected.

Adolescent↗
PubMed1995

Autologous glutaraldehyde-treated pericardial valved conduit: an experimental study.

Extracardiac conduits in the form of allografts and synthetic tubes containing heterograft valves have been used widely in the management of ventricular outflow abnormalities and for establishing ventriculoarterial continuity. These procedures are limited by long-term calcification as well as by formation of neointimal peel, necessitating reoperation. In an effort to continue the search for an alternative conduit, we designed and evaluated a valved sinus-bearing conduit fashioned out of autologous pericardium treated with glutaraldehyde. The construction of the conduit is described. The results of implantation of these conduits in 12 sheep showed no progression of gradients, fresh regurgitation, or evidence of wall or cusp calcification 9 months after implantation.

Animals↗
PubMed1995

Pulmonary autograft for aortic valve replacement in rheumatic disease: a caveat.

Pulmonary autograft replacement of the aortic valve offers an attractive option in the younger patient with growth potential and long-term survival. In our institution between January 1990 and August 1994, 78 patients have undergone this procedure. The mean age was 18.6 +/- 7.36 years (range, 1 to 41 years). The etiology was rheumatic in 63 patients (80.7%). Aortic regurgitation was the predominant lesion in 60 patients (76.9%). Significant mitral regurgitation requiring operation was present in 22 patients (28.2%). All patients underwent pulmonary autograft replacement of the diseased aortic valve and the mitral valve was repaired in 22 patients. There were no hospital mortality, endocarditis, or thromboembolism in the series up to date. There have been two late non-cardiac deaths. Five patients (6.4%) required reoperation, one for mitral repair failure and four for autograft failure. Acute rheumatic valvulitis was demonstrated in one of the reoperated patients. Echocardiography of 68 patients followed up more than 2 months show progression of aortic regurgitation more than 2/4+ in 12 patients (15.4%). Four of these patients have been reoperated without mortality. In conclusion, although the Ross procedure remains a safe and attractive alternative in aortic valve operation, the progression of aortic regurgitation, especially in the younger patient with rheumatic etiology, remains a concern.

Adolescent↗
PubMed1995

Extended transseptal versus conventional left atriotomy: early postoperative study.

BACKGROUND: Mitral valve operations require excellent exposure. The description of an extended vertical transseptal atriotomy by Guiraudon and associates promises to provide optimal exposure of the mitral valve. A prospective study was carried out to evaluate the merits of the extended vertical transseptal atriotomy in comparison with the conventional left atriotomy for mitral valve operations. METHODS: Conventional atriotomy was performed in 24 patients (group I) whereas 65 patients underwent the extended vertical transseptal offroach (group II). They were similar in age, sex, cause of disease, New York Heart Association functional class, left atrial size, and left ventricular function. The early postoperative rhythm changes in these two groups were compared. Statistical studies to analyze the significance of incidence of junctional arrhythmia in these two groups were carried out. RESULTS: Of the 24 patients in group I, 3 had development of transient junctional rhythm after operation, lasting less than 24 hours. None had this arrhythmia at the time of discharge. Of the 65 patients in group II, junctional rhythm was documented in 25, with a rate of occurrence of 38% (95% confidence interval, 27.6% to 52.2%). At the 6-week follow-up, 3 patients still had this junctional rhythm, with a failure to recover rate of 12% (3 of 25). CONCLUSIONS: The surgical exposure was considered excellent and closure of the atriotomy was thought to be easy in group II. However, this should be balanced against a significant (38%) incidence of transient junctional rhythm in the early postoperative period in group II, probably from injury to sinus node artery or atrial conduction pathways.

Adolescent↗
PubMed1995

Ball valve (Smeloff-Cutter) aortic valve replacement without anticoagulation.

BACKGROUND: Because of the difficulty of permanent anticoagulation in our young population, Smeloff-Cutter ball valves have been used since 1986 at our institution for aortic valve replacement in selected patients without permanent anticoagulation therapy. METHODS: The availability of a satisfactory follow-up system since July 1988 suggested a study of all 47 patients operated on since then and followed for a mean of 43.2 months (range, 16 to 78 months). Mean age was 26.3 years, 98% were in sinus rhythm, and 16 patients (34%) had concomitant mitral repair. RESULTS: There were no hospital deaths. Three patients were lost to follow-up at a mean of 27 months. Four late deaths occurred (8.5%), two of them sudden, with actuarial survival at 6 years of 91% +/- 4.3%. There were a total of five embolic events (2.9%/patient-year). For isolated aortic valve replacement only, with antiaggregant therapy (n = 29), the incidence was 0.9%/patient-year. For all patients receiving antiaggregant agents (n = 43), it was 3.02%/patient-year. There were no known cases of valve thrombosis. Reoperation was required in 5 patients. CONCLUSION: Aortic valve replacement with the Smeloff-Cutter ball valve might be a valid alternative for young patients unable to maintain regular anticoagulation.

Actuarial Analysis↗
PubMed1995

Aortic valve replacement with freehand autologous pericardium.

Fifty-one patients with a mean age of 31.2 years underwent aortic valve replacement with glutaraldehyde-treated autologous pericardium. Pure aortic regurgitation was present in 28 (54.9%), stenosis in 9, and mixed disease in 14. Simultaneous mitral valve repair was done in 17 patients and replacement in 1. There were no hospital and two late deaths. Three patients required reoperation because of failure of the pericardial valve as a result of infective endocarditis in two (5 and 31 months after operation) and commissural tear at 8 months in another. One patient underwent reoperation at 24 months because of failure of the mitral valve repair. The pericardial aortic valve, which had 2+ regurgitation since the first operation, was also replaced. Macroscopic and microscopic examination findings in the excised pericardium were excellent. No thromboembolic events have been detected and no patient received anticoagulation therapy except one after mitral valve reoperation and replacement with a mechanical valve. The actuarial survival was 84.53% +/- 12.29% at 60 months, freedom from failure of the aortic reconstruction 83.83% +/- 8.59%, and freedom from any event 72.59% +/- 12.79%. Doppler echocardiographic study at most recent follow-up showed a mean gradient of 12.56 +/- 8.10 mm Hg and mean regurgitation on a scale from 0 to 4+ of 0.80 +/- 0.66. Although the maximum follow-up is only 5 years, the results obtained so far encourage us to continue replacing the aortic valve with stentless autologous pericardium.

Adolescent↗