Search PubMed⌕ Search

Biomedical subjects

G Prabhakar

Publications and source records attributed to G Prabhakar.

At least 37 records · Page 2Linked to original sources
PubMed1994

Complex chromosomal rearrangements: some breakpoints may have cellular adaptive significance.

Cytogenetic study of a 3-year-old girl with developmental delay and some minor abnormalities revealed a complex chromosome rearrangement (CCR) involving seven chromosomes with eight breakpoints, leading to monosomy of segment 5q15-q22. According to breakpoint distribution, CCRs may be classified as those with primary intrachromosomal abnormalities (including inversions, insertions, duplications, etc.) and those without them. Only the latter group of CCRs was used in this analysis. Comparison of theoretical and observed breakpoint distributions in 33 cases demonstrated that recurrent involvement of some chromosome(s) ("re-entry") occurs more frequently than expected. One possible explanation for this observation suggests that the initial event leads to an unstable provisional rearrangement, and subsequent breaks are necessary to stabilize the karyotype.

Child, Preschool↗
PubMed1994

Glutaraldehyde, gamma-carboxyglutamic acid and calcium in explanted bioprosthetic heart valves.

This paper describes the determination of glutaraldehyde, gamma-carboxylglutamic acid (gamma-CGA) and calcium concentrations in nine bioprosthetic heart valves after explantation. The glutaraldehyde and gamma-CGA were determined by high performance liquid chromatography (HPLC) procedures and the calcium by atomic absorption spectrometry. Glutaraldehyde was detectable in only two of these valves at levels of 17% and 2% of that present in an unimplanted valve. The results indicate that there is no correlation between gamma-CGA and calcium deposition, indicating that the gamma-CGA is probably absorbed onto the forming calcium deposit from the circulation and does not contribute to the calcification process, and that the acid hydrolysable glutaraldehyde decreases with time during implantation. There is, however, no correlation between the duration of implantation and the decrease in glutaraldehyde concentration.

1-Carboxyglutamic Acid↗
PubMed1993

Human cytogenetics. A current overview.

Chromosomal abnormalities are the basis for a substantial proportion of human morbidity and mortality. During the past 35 years, the field of human cytogenetics has helped to elucidate the etiology of many congenital malformation/mental retardation syndromes. Through adaptation of technological advances and integration of molecular biological techniques, cytogenetics continues to contribute significantly to our knowledge of clinical genetics, chromosomal fine structure and function, gene mapping, and prenatal diagnosis. This review outlines the basic concepts, recent findings, and current laboratory approaches to cytogenetic diagnosis.

Amniocentesis↗
PubMed1993

Triple-valve operation in the young rheumatic patient.

Multiple-valve operation for the young rheumatic patient remains a problem. There is a paucity of information on the results of repair versus replacement in this age group. Between July 1988 and December 1991, 242 patients less than 20 years of age underwent a valve operation for rheumatic heart disease at our institution. Twenty-four (9.9%) of them had simultaneous mitral, aortic, and tricuspid valve procedures. The mean age was 14.71 years. All 24 patients were in functional class III or IV preoperatively. Valvar regurgitation was the predominant lesion. Four patients (16.7%) had active rheumatic myocarditis at the time of operation. Valve repair was attempted in the absence of infective endocarditis. Triple-valve repair was possible in 12 patients (50%). The hospital mortality rate was 16.7%. Reoperation was performed after repair in 9 patients (45%) without any deaths. The reason for reoperation was failure of the mitral valve repair in all patients, and the cause was technical in 3 patients, progression or recurrence of rheumatic myocarditis in 5, and endocarditis in 1 patient. The three late deaths (15%) were in patients who had mitral valve replacement. Valve repair was associated with a higher reoperation rate, and replacement of left-sided valves was associated with a higher early and late mortality. In conclusion, although valve repair would be ideal in the young rheumatic patient, multiple-valve repair is associated with a high reoperation rate.

Adolescent↗
PubMed1993

Congenital aneurysm of the muscular interventricular septum.

Cardiac aneurysms are rare in the paediatric age group, and are classified as congenital when the aetiology cannot be demonstrated. We report a 1-year-old patient with a congenital aneurysm of the muscular interventricular septum. Ventricular septal aneurysmectomy was performed successfully.

Echocardiography↗
PubMed1993

New prosthetic ring for aortic valve annuloplasty.

Aortic valve repair is recently receiving more attention. To broaden the indications for this procedure a prosthetic annuloplasty ring has been developed and tested in animals. Thirty-two sheep underwent implantation of such a ring in the pulmonary (14) and aortic (18) positions. In the 12 survivors followed for a maximum of 200 days the ring was found epithelialized and free from thrombus. One ring was dehiscent; no haemolysis was detected. It is concluded that a small clinical study is warranted.

Animals↗
PubMed1993

The challenge of valve surgery in a developing population.

Between August 1988 and October 1992, 1,052 patients underwent 1,522 valve procedures in our institution. Their mean age was 32.69 years (range 1-90). The etiology was rheumatic in 724 (68.8%), congenital in 120 (11.4%), degenerative in 99 (9.4%), infective in 58 (5.5%) and ischemic in 17 (1.6%). The mean preoperative functional class (NYHA) was 2.95 and 780 (74.1%) were in sinus rhythm. Repair was possible in 885 (58.1%) valves. The rate of repair versus replacement was 94.5% for the tricuspid, 56.2% for the mitral and 43.6% for the aortic valve. The total hospital mortality was 4.18%. For isolated mitral surgery it was 2.94%, for isolated aortic 4.12% and for isolated tricuspid 15%. Double valve surgery carried a mortality of 3% and triple valve surgery 13%. Hospital mortality for isolated mitral and isolated aortic surgery was lower for repair than for replacement (1.5% vs. 5% and 0 vs. 6.8%). The follow-up was 94.65% complete. The total incidence of embolic events was 2.93% with an actuarial freedom at 48 months of 92.71 +/- 5.35% for repair, 88.22 +/- 6.26% for replacement and 90.31 +/- 5.65% for patients with repair and replacement. Late mortality was 4.5%. The actuarial survival excluding hospital deaths was 94.89 +/- 2.10% for repair, 86.84 +/- 2.84% for replacement and 91.33 +/- 2.73% for the mixed group. The reoperation rate was higher for repair (13%) than for replacement (0.1%). This rate was highest for the rheumatic mitral patients with an age below 20 years (25.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The Ross procedure in a young rheumatic population: early clinical and echocardiographic profile.

The use of pulmonary autografts for aortic valve replacement is nearing its third decade. It is showing promise as a permanent aortic valve with its ability to grow with age. We report our experience of 45 patients with a mean age of 16.89 years over a three year period. Rheumatic heart disease was the cause of aortic valve dysfunction in 38 (84.4%) patients. Sixteen (35.5%) patients also underwent mitral valve repair. Echocardiographic examination revealed early reduction of aortic regurgitation and left ventricular dimensions, which remained stable in the short follow up period. There were no early or late deaths. One patient required reoperation for a regurgitant pulmonary autograft at two years. We conclude that pulmonary autograft transplantation to the aortic root seems to offer a near permanent solution in a young population affected by rheumatic valve disease.

Adolescent↗
PubMed1993

Surgery for organic rheumatic disease of the tricuspid valve.

The paucity of reports on the incidence and management of organic involvement of the tricuspid valve in rheumatic disease led us to carry out this retrospective study. Over a four and a half year period, of the 1052 patients undergoing valve surgery at our institution, 253 (24.05%) required tricuspid surgery. Organic involvement was noted in 115 (45.45%) of these patients. Definitive preoperative diagnosis was feasible by echocardiogram in only 48 (41.73%). Tricuspid regurgitation was present in all patients while detectable stenosis was present in 48 (41.7%). Annular dilatation was seen in 52 (45.2%). Primary repair was possible in 107 patients (93.0%). The reduction in tricuspid regurgitation remained stable at the last follow up in all but seven patients. Nine patients underwent reoperation in this study for failure of left-sided valve repairs, of which five needed reoperation on the tricuspid valve. All the five reoperated tricuspid valves had had dilated annuli at primary surgery. The presence or absence of annular dilatation did not cause any significant difference in early or late mortality. The presence of annular dilatation in the presence of left-sided valve lesions superimposed on organically involved tricuspid valves evokes the possibility of the presence of an organo-functional disease.

Adolescent↗
PubMed1993

Vanishing De Vega annuloplasty for functional tricuspid regurgitation.

Annuloplasty is performed for significant functional tricuspid regurgitation even if it is presumed that in some cases the regurgitation will regress spontaneously after correction of the left-sided lesion. In an attempt to avoid the drawbacks of a permanent annuloplasty, we used a reabsorbable De Vega annuloplasty in a selected group of patients. Of 73 patients with functional tricuspid regurgitation operated on between May 1989 and May 1991, 25 with pulmonary arteriolar resistance below 400 dyne.sec.cm-5 underwent a De Vega annuloplasty with 2-0 polydioxanone suture. The diagnosis of significant functional tricuspid regurgitation (mean 2.74 +/- 1.05) was established by transthoracic color Doppler echocardiography in all patients. The degree of functional tricuspid regurgitation and pulmonary arteriolar resistance were measured with the patients anesthetized. In 16 patients the regurgitation remained severe (3+ to 4+) and in 9 it was moderate (2+). Twenty-three patients had mitral (12 repairs, 11 replacements) and 9 had aortic (4 repairs, 5 replacements) valve operations. The immediate postbypass residual functional tricuspid regurgitation was 0 to 1+ in 23 and 0 in 2. There was 1 (4%) operative death. The maximum follow-up period was 24 months (mean 13.9 months). There were 2 (8.3%) late deaths. Six patients underwent reoperation because of mitral dysfunction. Four of them who were reoperated on between 2 and 5 weeks after the initial procedure showed no recurrence of functional tricuspid regurgitation. The other 2, reoperated on at 5 and 10 months after the first operation, had recurrence of functional tricuspid regurgitation. Visual inspection of these two tricuspid valves showed a dilated anulus with otherwise normal valves. All surviving patients are in New York Heart Association functional class I or II without significant functional tricuspid regurgitation (mean 0.78 +/- 0.56). We concluded that functional tricuspid regurgitation in patients with low pulmonary arteriolar resistance can be adequately treated by a vanishing De Vega annuloplasty, which will stent the tricuspid anulus for about 4 months.

Adolescent↗
PubMed1992

New surgical technique for type B aortic interruption.

Restoring continuity of the aortic arch in aortic interruption continues to be a problem in terms of both surgical technique and long-term results. We report here a surgical technique using the left subclavian artery along with an aberrant right subclavian artery to form a conduit in a patient with type B interruption, to reestablish aortic continuity.

Aorta, Thoracic↗