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Biomedical subjects

C A Hajivassiliou

Publications and source records attributed to C A Hajivassiliou.

At least 19 recordsLinked to original sources
PubMed2004

Outcome after implantation of a novel prosthetic anal sphincter in humans.

BACKGROUND: A novel prosthetic anal sphincter (PAS) has been developed that aims to occlude by flattening and angulating the bowel, reproducing the action of the puborectalis muscle. The safety of the PAS has been confirmed in biomechanical, in vitro and long-term animal survival studies. The Medical Devices Agency approved implantation in 12 patients. METHODS: The PAS was placed in the pelvis around the anorectal junction via a transabdominal approach in 12 patients with severe faecal incontinence. The device was activated 6 weeks after surgery. Fibreoptic examination of the mucosa below the device was undertaken at various intervals during review. RESULTS: At a median follow-up of 59 (range 30-72) months nine of the 12 patients had a functioning PAS. There were no device-related infective complications after the initial operation but one patient developed pseudomembranous colitis and had the device removed. The PAS was effective in restoring continence in ten of 11 patients. Median (range) Cleveland Clinic continence scores improved from 16 (7-20) before to 3 (0-7) after surgery. In two patients the PAS was eventually removed owing to infection after revisional surgery. There was no clinical or histological evidence of gastrointestinal mucosal ischaemia. CONCLUSION: The PAS was effective in restoring continence. There was no device-related infection after the initial operation, no device erosion and no clinical or histological evidence of gastrointestinal ischaemia.

Adult↗
PubMed2003

Intestinal obstruction in neonatal/pediatric surgery.

Intestinal obstruction in the newborn infant and older child may be due to a variety of conditions, including atresia and stenosis, annular pancreas, malrotation, duplication cyst, meconium ileus, meconium plug syndrome and neonatal small left colon syndrome, Hirschsprung's disease, neoplasia, trauma, and other rarer causes. The mode of presentation can be acute or more chronic with systemic upset due to shock. Neonates, more so than older children, with unrecognized intestinal obstruction deteriorate rapidly, show an increase of associated morbidity and mortality and appropriate surgical treatment becomes more hazardous. Early diagnosis depends largely on the prompt detection of obstructive manifestations by the clinician and the subsequent accurate interpretation of radiographic findings and other investigations, leading to definitive treatment, which should always be preceded by appropriate resuscitation/preparation of the infant/child. Management of intestinal obstruction will almost always be surgical, apart from some notable exceptions and all are discussed in more detail. With the advent of pediatric and neonatal intensive care and multidisciplinary care, the morbidity and mortality of cases of intestinal obstruction reported in current series is generally extremely low and mainly determined by the coexistence of other major congenital anomalies (eg, cardiac), delays in diagnosis and treatment or coexisting medical conditions. Newer treatments and future developments may reduce the residual mortality in such cases as ultrashort-bowel syndrome.

Child↗
PubMed2000

Use of Doppler ultrasound and 3-dimensional contrast-enhanced MR angiography in the diagnosis and follow-up of post-traumatic high-flow priapism in a child.

We report a 7-year-old boy with post-traumatic arterial priapism. Doppler US could not reliably identify or exclude a fistula. MR angiography did not demonstrate an arteriovenous fistula and the child was treated conservatively. The ideal imaging modality should demonstrate the presence or absence of a clinically significant causative lesion which, in high-flow arterial priapism, may need intervention. Three-dimensional, contrast-enhanced MR angiography appears to fulfil these requirements. On the basis of the non-invasive imaging findings, invasive intervention was avoided in this case with a successful outcome.

Child↗
PubMed1999

Uneven pressure application by the artificial urinary sphincter: an explanation for tissue ischaemia?

OBJECTIVE: To determine, in an in vitro study, the pressure inside the AMS 800 (American Medical Systems, USA) sphincter placed around porcine intestine and to correlate this with the pressure retention for liquids, in an attempt to explain the increased sensitivity of bowel to ischaemic injury when the artificial urinary sphincter is used around bowel neo-urethral segments. MATERIALS AND METHODS: Segments of porcine intestine were placed in a specially designed mechanical jig and an AMS 800 sphincter placed around the segment. The device was inflated by injecting water and the cuff pressure measured. Water was infused into the bowel and the pressure at which leakage occurred through the sphincter recorded. At each inflation pressure, a catheter-tipped microtransducer was used to measure the pressure inside the cuff-fold. It was then placed in the centre of the cuff lumen, rotated by 360 degrees and the pressure continuously recorded. RESULTS: The cuff occluded the lumen by creating a 'triple-cushion' effect. The fluid retention pressure was 49% of the cuff pressure. There were directional differences in the pressure measured inside the bowel lumen. The pressure was also disproportionately higher inside the cuff folds than in the centre of the sphincter, and increased rapidly with inflation of the cuff. CONCLUSION: The thin wall of the bowel may 'crenate' inside the high-pressure areas in the cuff folds and this may explain the increased sensitivity of bowel to ischaemic injury in such cases.

Animals↗
PubMed1999

A review of the complications and results of implantation of the AMS artificial urinary sphincter.

The history and evolution of devices designed to achieve urinary continence are reviewed. Passive and active (including volume and pressure regulated) devices are described in detail. Meta-analysis of the published studies revealed that continence improved in 88% of patients and total continence was achieved in 73%. Global revision rate was 32%. Urethral erosion occurred in approximately 12%, infection in 4.5% and mechanical complications in 14% of cases. The complications relating to the AMS artificial urinary sphincter are analyzed. The majority of patients (> 85%) required only one revision. 22% of complications were due to mechanical malfunction. Infection comprised 12.9% of complications. The patterns of total revisions followed a double exponential decay curve: 50% of revisions were performed within 8 months and 90% within 3 years of implantation. Complications were still reported several years postimplantation. This review analyzes the problems relating to the application of pressure and the presence of foreign material around the urethra and exemplifies the requirement for long-term specialist follow-up of these patients.

Animals↗
PubMed1998

A personal audit of pediatric surgical training before implementation of the Calman guidelines.

PURPOSE: The purpose of this study was to audit the surgical training experience of a Higher Surgical Trainee in the United Kingdom during the tenure of the posts of Career Registrar, Research Fellow, and Senior Registrar from August 1992 to July 1997. Although the Report of the Working Party on the UK Specialist Medical Training (the Calman report) was published during this study, the training remained the same because the author elected not to transfer to the new grade. METHODS: A 39-field database was designed, and the surgical experience was entered prospectively. The data were analyzed chronologically according to age of patient, condition, level of supervision, and nature of admission (emergency, elective). RESULTS: Two thousand two hundred ninety patients or operations are presented. Only a small number of patients underwent surgery during the research year (1994). The pattern of operating changed from one of large numbers of supervised to one of more major procedures. The numbers of neonates and younger infants who underwent surgery increased significantly, and the level of supervision changed allowing more autonomy toward the end of the training period. This trend was reversed partially during the period of overseas secondment. The results are compared with those in a recently published USA/Canadian study. CONCLUSION: The volume of work undertaken by the trainee ensures adequate exposure to a wide range of procedures to achieve a satisfactory level of competence. Changes that may affect this are discussed.

Child, Preschool↗
PubMed1998

Recurrent necrotizing enterocolitis associated with episodes of supraventricular tachycardia.

The case of a 5-month-old baby with congenital heart disease and recurrent episodes of refractory supraventricular tachycardia (SVT) is presented. Severe segmental necrotizing enterocolitis (NEC) developed in the patient after one prolonged episode of SVT that required a limited right hemicolectomy. Further episodes of SVT were associated with recurrence of NEC requiring multiple laparotomies. The pathogenesis and therapeutic implications of this process are discussed in view of the potentially multiple pathological processes involved.

Colectomy↗
PubMed1998

Non-invasive measurement of colonic blood flow distribution using laser Doppler imaging.

BACKGROUND: This study tested a prototype laser Doppler scanner for the measurement of human colonic blood flow. METHODS: Blood flow distribution was assessed in human colon during operation in six controls and in six patients with inflammatory bowel disease undergoing colectomy. Image processing software analysed several hundred reading points, expressing average flow in perfusion units. RESULTS: Blood flow in the colon was not significantly lower in the control group than in patients with inflammatory bowel disease (mean(s.e.m.) 297.8(24.5) versus 347.2(59.0) perfusion units, P = 0.12). Intestinal colonic mural blood supply was demonstrated up to a distance of 6 cm and ischaemia demarcation lines were identified before the onset of visible changes. CONCLUSIONS: This prototype laser Doppler flowscanner overcomes the previous limitations of laser Doppler flowmeters and may have many clinical and research applications.

Adult↗
PubMed1998

Effect of a novel prosthetic anal neosphincter on human colonic blood flow.

BACKGROUND: An artificial anal sphincter has been developed which aimed to simulate the normal physiology of the anorectum. As a prelude to human implantation the present study reports the effect of inflation of this device on colonic perfusion in patients undergoing colectomy, which was assessed by using a laser Doppler scanner. METHODS: Eleven patients (median age 49.8 (range 24.3-78.7) years) were studied. Five patients had inflammatory bowel disease (IBD). The neosphincter was placed around the bowel and progressively inflated. The model was designed so that blood flow changes to the colon under the neosphincter would be reflected in the distal segment of the bowel, which could be scanned by the laser Doppler scanner. RESULTS: The blood flow in the colon distal to the device was significantly higher in patients with IBD (mean(s.e.m.) 288.6(71.9) versus 211.1(57.6) perfusion units; P < 0.001). The mean(s.e.m.) 'biological zero' value was 46(14) perfusion units. Blood flow distal to the neosphincter decreased progressively with increased sphincteric compression by 0.66 per cent per mmHg applied pressure in controls and 0.35 per cent per mmHg in patients with IBD (P < 0.05). CONCLUSION: These results suggest that at the planned operating occlusion pressure (less than 45 mmHg) this neosphincter should not put the vascularity of the human colon at risk.

Adult↗
PubMed1997

Assessment of a novel implantable artificial anal sphincter.

PURPOSE: The aim of the study was to test a new implantable artificial anal sphincter in the porcine model. METHOD: The artificial sphincter, which includes an inflatable expander that compresses and flattens the bowel against a pillow, was implanted in 16 animals and studied for periods of up to 20 weeks. The anal sphincters were destroyed, and the efficacy of the device in rendering the animals continent was studied. RESULTS: Of the 11 animals in which the artificial sphincter was regularly closed, 8 completed the study and were continent during 85 percent of activation times. There was no evidence of ischemic injury. Major complications were related only to failure of the control pumps of the device. CONCLUSION: This study suggests that this neosphincter produces fecal continence without intestinal ischemia. At present reliability is limited only by the performance of the pump.

Anal Canal↗
PubMed1997

Ectomesenchymoma: one or two tumors? Case report and review of the literature.

Ectomesenchymoma has not previously been reported in a patient with the cutaneous nevus syndrome. A case of perineal ectomesenchymoma is presented with unusual cytogenetic findings. The significance of these is discussed and the world literature reviewed. This is the first such case reported.

Combined Modality Therapy↗
PubMed1996

Anorectal angle enhances faecal continence.

This study was performed with an in vitro model to assess the relative importance of sphincter pressure and anorectal angulation in maintaining faecal continence. Water and semisolid material were infused separately into porcine intestine compressed by an inflatable cuff until leakage was observed. Angulation of the bowel with respect to the cuff was 180 degrees and then 90 degrees. With water, holdback pressure was independent of angulation. In contrast, when semisolid material was used, angling the bowel to 90 degrees increased holdback pressure by at least 100 per cent. Measurements taken in solid tubes demonstrated that both a restriction in the tube and an unconstricted 90 degrees bend produced a resistance to flow of the semisolid material which was dependent on flow rate. These data suggest that liquid is retained in the rectum by occlusion pressure alone, whereas the retention of semisolid material is enhanced by angulation.

Anal Canal↗