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Biomedical subjects

R G McWilliams

Publications and source records attributed to R G McWilliams.

17 recordsLinked to original sources
PubMed2001

Perianeurysmal fibrosis: a relative contra-indication to endovascular repair.

OBJECTIVE: Perianeurysmal fibrosis (PAF) with involvement of neighbouring viscera can render open repair of inflammatory aneurysms technically difficult and therefore hazardous. For this reason, endovascular repair (EVAR) has been advocated as the preferred approach for this condition. EVAR is known to induce a systemic inflammatory response in patients but the nature of the local response remains unknown. If significant, such a response could exacerbate rather than ameliorate PAF. The aim of the study was to examine the incidence, course and consequences of perianeurysmal fibrosis detected by computerised tomography (CT) before and after EVAR. MATERIAL AND METHODS: The clinical records of patients treated by EVAR and followed for at least 6 months were reviewed. Pre and post-operative CT images were independently graded for PAF by three radiologists according to a standard protocol. RESULTS: PAF was documented preoperatively in six out of a total of 61 patients. In two of these PAF worsened after EVAR resulting in ureteric obstruction and hydronephrosis requiring ureteric stents. In the remaining 4 patients PAF did not reduce postoperatively. PAF of low grade developed postoperatively in 10 out of 55 patients (18%) in whom there was no evidence of PAF on preoperative imaging. Median follow-up was 18 months (range 6-36 months). The development of periaortic fibrosis de novopostoperatively was statistically significant (McNemar's test p=0.002). CONCLUSION: EVAR does not seem to reverse PAF if this is present preoperatively and it induces this condition in approximately one sixth of patients without evidence of preoperative PAF. The potential for this adverse inflammatory local response should be taken into account when considering EVAR for treatment of aneurysms with perianeurysmal fibrosis and must be weighed against the perceived benefits of this approach.

Aged↗
PubMed2000

Doppler ultrasound diagnosis of a superficial ulnar artery.

The ulnar artery may lie in a superficial position in the forearm as a normal anatomical variant. We report a case where this variant was clinically mistaken for phlebitis but was diagnosed correctly with Doppler ultrasound. In this report, we discuss the anatomy and clinical relevance of the superficial ulnar artery.

Adult↗
PubMed2000

Freedom from endoleak after endovascular aneurysm repair does not equal treatment success.

OBJECTIVE: To determine whether freedom from endoleak after endovascular repair of abdominal aortic aneurysm (EVAR) is a reliable guide to freedom from persistent or recurrent pressurisation of the aneurysm sac (endotension) and therefore freedom from risk of rupture. PATIENTS AND METHODS: The records of 55 patients followed for more than 3 months after EVAR were reviewed to correlate the presence or absence of endoleak on contrast-enhanced CT and/or angiography with changes in maximum aneurysm diameter (DMAX). RESULTS: in 22 (40%) patients there was no significant change in DMAX during follow-up. In 21 of these no endoleak was observed on CT or angiography. One patient developed a secondary side-branch endoleak which remains under observation. In 18 (33%) patients, DMAX decreased during follow-up. Thirteen of these remained free of endoleak. Four patients developed secondary endoleaks which were treated by secondary intervention. One patient with persistent primary endoleak suffered fatal aneurysm rupture three days before planned intervention. DMAX increased in 15 (27%) patients. In only five of these could an endoleak be identified on CT and/or angiography. One primary side-branch endoleak persists following failed embolisation. Four secondary endoleaks have been corrected by secondary intervention. Four of the remaining 10 patients died suddenly from unknown cause. All had DMAX greater than 65 mm at last follow-up. One patient underwent late conversion, which suggested continued pressurisation through thrombus at the site of a "sealed" primary proximal endoleak. Two patients are scheduled to undergo embolisation of patent side-branches revealed only by Levovist enhanced Duplex scanning and three patients remain under observation. CONCLUSION: Freedom from endoleak on conventional imaging incorrectly suggested freedom from endotension in 10 (18%) of our patients. Follow-up after endovascular repair must include regular measurement of DMAX and/or aneurysm sac volume to identify those patients who remain at risk of rupture.

Aged↗
PubMed1999

Use of contrast-enhanced ultrasound in follow-up after endovascular aortic aneurysm repair.

PURPOSE: To investigate the use of contrast-enhanced ultrasound in the detection of endoleak after endovascular repair of abdominal aortic aneurysm. MATERIALS AND METHODS: Eighteen patients underwent follow-up on 20 occasions after endovascular aortic aneurysm repair by arterial-phase contrast-enhanced spiral computed tomography (CT). All patients had unenhanced color Doppler ultrasound and Levovist-enhanced ultrasound on the same day. The ultrasound examinations were reported in a manner that was blind to the CT results. CT was regarded as the gold standard for the purposes of the study. RESULTS: There were three endoleaks shown by CT. Unenhanced ultrasound detected only one endoleak (sensitivity, 33%). Levovist-enhanced ultrasound detected all three endoleaks (sensitivity, 100%). Levovist-enhanced ultrasound indicated an additional six endoleaks that were not confirmed by CT (specificity, 67%; positive predictive value, 33%). In one of these six cases, the aneurysm increased in size, which indicates a likelihood of endoleak. Two of the remaining false-positive results occurred in patients known to have a distal implantation leak at completion angiography. CONCLUSION: In this small group of patients, contrast-enhanced ultrasound appears to be a reliable screening test for endoleak. The false-positive results with enhanced ultrasound may be due to the failure of CT to detect slow flow collateral pathways. Although the number of patients in this study is small, enhanced ultrasound may be more reliable than CT in detecting endoleak.

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PubMed1998

Sources of error in intra-arterial pressure measurements across a stenosis.

OBJECTIVE: To investigate potential errors associated with different techniques of intra-arterial pressure measurement at angiography. MATERIALS AND METHODS: An experimental model of an arterial stenosis was developed. Experiments were performed to assess the relevance of catheter position, catheter direction and catheter type on the recorded intraluminal pressure. Transstenotic pressure gradients were recorded with and without angiographic catheters crossing the stenosis. RESULTS: At physiological flow rates angiographic catheter type does not influence the recorded pressure. At high flow rates through tight stenoses there is a significant catheter-related difference in recorded pressure adjacent to a stenosis. Downstream pressures may be altered by up to 85 mmHg when standard angiographic catheters are placed across a stenosis. CONCLUSION: The different techniques employed to measure pressure differences across a model stenosis may introduce significant errors up to 85 mmHg. Care must be taken when pressure measurements alone are used to interpret the clinical significance of a stenosis. In low flow conditions there may not be a detectable pressure gradient across a 95% stenosis.

Angiography↗
PubMed1997

Pseudolipoma of inverted Meckel's diverticulum: clinical, radiological and pathological correlation.

Three cases of isolated inverted Meckel's diverticulum are described. In two cases an initial pathological diagnosis of small bowel lipoma was suggested. In a third case central fat was demonstrated on CT and peristalsis of the intraluminal polypoid mass was observed during US examination. In all three cases small bowel enema examination demonstrated the lesion. Correlation of the clinical, radiological and pathological features is emphasised, as this will allow the correct diagnosis.

Adult↗
PubMed1996

Case report: The "veiled right kidney sign"--an ultrasound finding in retroperitoneal perforation of the duodenum.

We report a case of traumatic duodenal perforation where the diagnosis was first considered during abdominal ultrasound examination. A subsequent CT scan identified the site of perforation which was confirmed at laparotomy. This condition typically produces few clinical signs or symptoms initially but has a high mortality related to delayed diagnosis. The ultrasound findings that prompted early diagnosis are described.

Adult↗
PubMed1995

Pseudothrombosis of the infra-renal inferior vena cava during helical CT.

Pseudothrombosis of the infra-renal vena cava is a frequent finding during post-contrast helical computed tomography (CT) studies of the abdomen. Three hundred consecutive patients undergoing contrast-enhanced helical studies were evaluated prospectively to document the incidence of pseudothrombosis. Typical CT findings are illustrated and a significant difference in incidence between the male and female population noted.

Female↗
PubMed1995

Case report: the demonstration of aortocaval fistulae by helical computed tomography.

We report the helical computed tomography findings in two patients with spontaneous aortocaval fistula (ACF) complicating abdominal aortic aneurysm. The use of overlapping slices produced high quality multiplanar reformats which provided anatomical information about the likely site of the ACF and also the relationship of the renal arteries to the neck of the aneurysm.

Aged↗
PubMed1994

The risk of blood splash contamination during angiography.

Blood splash contamination of the conjunctivae or buccal mucosa may occur during angiography and angioplasty. Since there is a risk of contracting Hepatitis B or HIV via this route, staff should be aware of this potential source of infection. The use of protective masks and goggles or glasses should be considered. We have studied the risk of contamination by asking both the radiologist and angiography nurse to wear spectacles and disposable masks during 100 consecutive angiographic procedures. The number of splashes was counted at the end of each procedure. Blood splashes occurred in seven procedures and there was a total of 23 splashes during the study. In conclusion, we believe that there is a significant risk of conjunctival or mucosal contamination with blood during angiographic procedures and given the potential seriousness of transmission of Hepatitis B or HIV, radiologists and nursing staff must be aware of this risk.

Angiography↗
PubMedDate not supplied

Graft distortion after endovascular repair of abdominal aortic aneurysm: association with sac morphology and mid-term complications.

PURPOSE: To investigate the incidence, significance, and mechanism of stent-graft distortion after endovascular repair (EVR) of abdominal aortic aneurysm. METHODS: EVR of abdominal aortic aneurysm was performed in 51 cases (49 modular, bifurcated; 2 tube). Thirty-two patients were followed for 6 or more months and had equivalent baseline and follow-up images which could be used to determine changes in graft configuration. Sac dimensions were measured using computed tomographic (CT) images and graft-related complications were recorded. RESULTS: Amongst 32 patients evaluated on follow-up, there was graft distortion in 24. Distorted grafts were significantly (p = 0.002) associated with sac diameter reduction (mean 5 mm) and sac length reduction (mean 8.1 mm). All graft-related complications occurred in the limbs of eight distorted grafts, with a mean reduction of sac length in this group of 7.8 mm on reformatted CT images. CONCLUSION: There was a highly significant association between graft distortion and limb complications, and reduced sac dimensions.

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