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Biomedical subjects

J R Boyle

Publications and source records attributed to J R Boyle.

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

Role of magnetic resonance angiography for assessment of abdominal aortic aneurysm before endoluminal repair.

BACKGROUND: A detailed knowledge of the morphology of the aorta and iliac arteries is an important prerequisite for successful endoluminal abdominal aortic aneurysm (AAA) repair. The best method of preoperative evaluation remains to be determined. METHODS: A prospective study was undertaken between January 1994 and July 1995 to assess the ability of computed tomography (CT), magnetic resonance angiography (MRA), colour duplex imaging and intra-arterial digital subtraction angiography (IA-DSA) to visualize AAA morphology. RESULTS: Eighty-two consecutive patients (64 men, 18 women) with AAA were assessed with MRA, contrast-enhanced CT, colour duplex imaging and IA-DSA. Median age was 74 (range 59-87) years and median AAA diameter was 5.7 (range 3.5-9.7) cm. Five patients were unable to tolerate CT or MRA examination. Seventy-seven patients underwent both CT and MRA. Of these, 55 also had a colour duplex scan and 32 underwent arteriography. The scans were assessed by an independent blinded observer. MRA was significantly better (P < 0.01) at visualizing AAA morphology compared with CT and colour duplex imaging. There was no statistically significant difference between MRA and arteriography. CONCLUSION: MRA is useful in patient selection for endoluminal AAA repair, as it avoids use of iodinated contrast medium and ionizing radiation.

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PubMed1998

Changes in referral practice, workload, and operative mortality after establishment of an endovascular abdominal aortic aneurysm program.

PURPOSE: To determine the change in referral practice following establishment of an endovascular abdominal aortic aneurysm (AAA) program. METHODS: A prospective audit of all elective admissions for AAA was established in January 1994 at the initiation of an endovascular AAA program. A comparison was made between this cohort and the elective AAA repairs performed between 1981 and 1993. RESULTS: Since January 1994, 213 AAA patients (177 men; median age 73 years, range 54 to 88) have been referred for potential endovascular aneurysm repair. To date, 142 patients have undergone elective surgery (41 endovascular and 101 conventional). Between 1981 and 1993, 304 patients (255 men; median age 69 years, range 45 to 86) had elective aneurysm repair. Comparison of the two time periods has revealed significant increases in the number of tertiary referrals (41.8% versus 9.5%, p < 0.01), annual operations (50 versus 23, p < 0.05), and overall mortality (12% versus 6.7%, p < 0.05), the latter attended by a significant increase in cardiorespiratory comorbidity. CONCLUSIONS: The higher elective AAA mortality rate since the establishment of an endovascular program reflects a change in referral practice and may be directly attributable to an increase in the number of high-risk patients. An endovascular AAA program has clinical and financial implications for the hospital concerned.

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PubMed1998

Torsion and kinking of unsupported aortic endografts: treatment by endovascular intervention.

PURPOSE: To describe the management strategies used to deal with twisted aortic endografts. METHODS AND RESULTS: Two patients with successfully excluded aortic aneurysms developed symptoms referable to previously undetected twists in their endografts (one EndoVascular Technologies [EVT] and one customized aortomonoiliac device). The limb graft occlusion in the EVT graft was treated surgically with a femorofemoral bypass, but the aortomonoiliac endograft was salvaged with percutaneous implantation of a Wallstent. During another aortomonoiliac procedure, suboptimal flow through the endograft was traced to contortion of the endograft as it passed over an angulated proximal aneurysm neck. An X-large Palmaz stent was deployed to support the graft at this point. CONCLUSIONS: Unsupported aortic endografts may develop twists and kinks during deployment that can lead to low outflow and graft occlusion. Endovascular techniques are available to repair these defects postoperatively, although more precise intraoperative assessment tools may identify these problems so that they can be corrected at the initial intervention.

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PubMed1998

Endovascular repair of aortic aneurysms in the the presence of a horseshoe kidney.

PURPOSE: To report two cases of endovascular aortic aneurysm exclusion in patients with a horseshoe kidney. METHODS AND RESULTS: Two male patients, one with a known horseshoe kidney and history of multiple previous laparotomies, presented with abdominal aortic aneurysms of approximately 6-cm diameter. Each was treated with a tapered aortomonoiliac polytetrafluoroethylene graft secured proximally with a Palmaz balloon-expandable stent. The endograft was sutured distally to a Dacron femorofemoral crossover graft. An anomalous renal vessel was sacrificed in one case. The aneurysms were successfully excluded, and the patients recovered without sequelae. CONCLUSIONS: Endovascular repair should be considered as a treatment option in patients with aortic aneurysm in the presence of a horseshoe kidney, particularly if the renal vasculature can be wholly preserved.

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PubMed1997

Microembolization during endovascular and conventional aneurysm repair.

PURPOSE: Endovascular aneurysm repair has been advocated as a "minimally invasive" alternative to conventional aneurysm surgery. However, because of manipulation within the aneurysm sac, endovascular techniques may result in massive microembolization. METHODS: In this study lower limb microemboli were quantified in 29 patients undergoing conventional (11 straight and 7 bifurcated grafts) and endovascular aneurysm repair (8 aortoiliac, 1 straight, and 2 bifurcated grafts) by insonation of the superficial femoral artery with a 2 MHz Doppler probe. Emboli were detected as high-intensity, short-duration signals on the background Doppler trace. Differentiation of gaseous emboli from particulate emboli was achieved by calculation of the sample volume length (emboli velocity x duration = sample volume length) for each embolus (N = 4927). Previous experiments had determined that a sample volume length < 1.4 cm represented particulate embolization. RESULTS: The number of gaseous, particulate, and total emboli were significantly greater in the endovascular group compared with the conventional group (p < 0.05). CONCLUSIONS: These data demonstrate that peripheral microembolization is significantly higher during endovascular aneurysm repair than during conventional surgery. Methods to reduce embolization must be developed before endovascular aortic surgery is widely adopted.

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PubMed1997

Ultrasound-based quantification of emboli during conventional and endovascular aneurysm repair.

PURPOSE: To differentiate and quantify the type and number of lower limb emboli occurring during endovascular aneurysm repair, as compared to conventional surgery. METHODS: Thirty-eight patients underwent elective infrarenal aneurysm repair using a conventional surgical approach in 18 and an endovascular procedure in 20. Emboli were detected using a Doppler ultrasound system with a 2-MHz transducer interrogating the mid superficial femoral artery. Lower limb emboli were differentiated as particulate or gaseous based on the physical distance traversed by the embolic signal. RESULTS: Significantly more particulate (median 108 versus 59, p = 0.015) and gaseous (134 versus 46, p = 0.008) emboli were detected during endovascular aneurysm repair as compared to conventional surgery. Clinically, no case of massive microembolization occurred in either group, but one patient in the conventional group required a femoral embolectomy, and three patients undergoing endovascular repair developed self-limiting trash feet postoperatively. In patients undergoing endovascular aortomonoiliac aneurysm repair, there was only a poor correlation between the number of particulate emboli and either procedural duration or operator experience. CONCLUSIONS: The apparent lack of a relationship between particulate embolization and operative time or technical experience suggests that manipulation of endoluminal devices within the aneurysm sac may not be the sole determinant of intraprocedural embolization. Other as yet undetermined factors may predict patients at high risk for massive embolization.

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PubMed1997

Improved respiratory function and analgesia control after endovascular AAA repair.

PURPOSE: Endovascular abdominal aortic aneurysm (AAA) repair has been proposed as a minimally invasive alternative to conventional surgery and may offer significant advantages in respiratory function and analgesic requirements due to the absence of an abdominal incision. METHODS: Respiratory function and analgesic requirements were quantified in 22 age-matched patients undergoing aneurysm repair under general anesthesia. Twelve patients underwent endovascular aneurysm repair, while 10 AAA patients had conventional surgery. One endovascular patient required conversion to conventional repair. RESULTS: The endovascular group required postoperative artificial ventilation for a shorter time (6 versus 21 hours, p < 0.05) and had lower PCA (patient-controlled analgesia) morphine consumption (41 versus 133 mg, p < 0.05) than the conventional group. The endovascular group also had significantly better forced expiratory volume and forced vital capacity at both 3 and 5 days when expressed as percentages of the preoperative values (p < 0.05). CONCLUSIONS: Endovascular AAA repair attenuates respiratory dysfunction associated with conventional surgery and reduces perioperative analgesia requirements.

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PubMed1997

Aortomonoiliac endovascular grafting: difficult solutions to difficult aneurysms.

PURPOSE: To describe a refined technique for aortomonoiliac endograft exclusion of abdominal aortic aneurysms (AAAs). METHODS: A tapered aortomonoiliac graft was prepared from an 8-mm thin-walled expanded polytetrafluoroethylene tube graft predilated proximally to 35 mm and tapered distally to 15 mm. The proximal graft was sutured to a 5-cm-long, predilated Palmaz stent, which was mounted on a 30-mm balloon and backloaded into a 21F packaging sheath. With the patient under general anesthesia and both common femoral arteries exposed, the endograft was anchored in the infrarenal aorta and subsequently passed into one iliac system, where it was anastomosed to the iliac or femoral vessels. The contralateral common iliac artery was occluded, and an extra-anatomic, femorofemoral, or iliofemoral bypass grafting was performed. RESULTS: Twenty of the 25 AAAs treated to date with this technique have been successful, with aneurysm exclusion achieved in 18 (2 minor distal endoleaks are scheduled for endovascular repair). The technical failures were analyzed, resulting in enhancements to the technique. Complications included 2 early (< 30 days) deaths, 1 case of minor embolization, 1 transient renal failure, 1 pulmonary embolus, and 1 wound infection. The only late complication was a graft infection localized to the groin. CONCLUSIONS: Aortomonoiliac endovascular aneurysm repair is effective in patients with AAAs involving the iliac arteries. Short-term results are acceptable, but long-term efficacy must be addressed before this procedure is widely adopted. Technical changes made in response to early learning curve problems have led to a safer, more reliable procedure.

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PubMed1997

TUR syndrome and endoscopic transanal resection: no evidence for a clinically important association in 38 procedures.

BACKGROUND: The TUR syndrome is well described after transurethral resection of the prostate. Endoscopic transanal resection (ETAR) is increasingly used to remove rectal lesions. METHODS: A prospective study of 38 ETARs in 21 patients was carried out over 2 years. Each patient was observed for symptoms and signs of TUR syndrome, and each had serial venous blood sampling and subsequent biochemical and haematological analysis during the perioperative period. RESULTS: No symptoms or signs typical of TUR syndrome were recorded. However, analysis of the biochemical variables using the Kruskal-Wallis one-way analysis of variance showed that there were statistically significant (P < 0.05) subclinical changes during the 24 h following the procedure affecting levels of serum sodium, potassium, total protein, albumin, lactate dehydrogenase, glycine, ammonia and serum osmolality. CONCLUSION: The changes in the electrolyte concentrations, although statistically significant, were not of the same magnitude as described previously in the TUR syndrome. The risk of a TUR-type syndrome in ETAR is small and serial blood tests, as detailed above, may safely be omitted.

Adenoma↗
PubMed1996

An unusual presentation of intestinal lymphangiectasia.

Intestinal lymphangiectasia is a rare disorder, usually presenting with protein-losing enteropathy leading to oedema and ascites. We describe a case that presented as an acute surgical emergency with pain and a mass in the right iliac fossa, which was successfully treated by resection of the involved segment of ileum.

Abdomen, Acute↗
PubMed1996

Proximal stent deployment without contrast during endovascular aneurysm repair: an improved technique.

PURPOSE: To describe a technique to enhance stent visibility on the fluoroscopic monitor during aortic endograft deployment. TECHNIQUE: To assist in accurate positioning and deployment of the proximal stent in a Parodi-type aortic endograft, the stent is affixed to the balloon so that the radiopaque marker sits at the stent's distal end. When the device is in position and the sheath is retracted, the stent and the radiopaque balloon markers are clearly seen on the fluoroscopic image. Using normal saline only to inflate the balloon allows the stent to remain visible throughout deployment. CONCLUSIONS: The use of saline rather than contrast medium for balloon inflation provides continuous visualization of the stent during expansion, thus facilitating accurate deployment and early recognition of balloon migration within the stent.

Angioplasty, Balloon↗
PubMed1995

Risk factors leading to arterial occlusion following diagnostic arteriography.

OBJECTIVES: Arteriography may precipitate occlusive complications in stenotic vessels by a toxic effect on the vascular endothelium, leading to intra-arterial thrombosis. The aim of this retrospective study was to determine the incidence of arterial occlusion following arteriography. METHODS: We studied 101 consecutive patients (71 male, 30 female; median age 72 years) undergoing percutaneous transluminal angioplasty (PTA) of stenotic lesions, which had been identified on diagnostic arteriograms performed a median of 109 days (range 6-519) previously. One hundred and thirty-one arterial stenoses suitable for PTA were identified in the patient cohort. RESULTS: Seventeen patients (17%) progressed to occlusion in the period between diagnostic arteriography and PTA. Stenoses in the femoro-popliteal segment (21%) progressed to occlusion more frequently than lesions of the iliac arteries (3%). Independent risk factors were analysed to determine the risk factors predisposing to arterial occlusion following diagnostic arteriography. Both groups were well matched for age and sex. The mode of presentation, the presence of ischaemic heart disease, hypertension, diabetes or current smoking habits did not predict progression of disease to arterial occlusion. However, the rate of occlusion appeared to be influenced by the proportion of patients taking anti-platelet medication (51% in non-occluders as compared to 11% in patients who occluded, 95% CI 0.1 to 10), and to the length of time between arteriography and PTA (median of 92 days in non-occluders as compared to 125 days in patients who occluded, 95% CI 21 to 57). CONCLUSIONS: These data demonstrate that occlusion of pre-existing arterial stenoses following diagnostic arteriography is significantly more frequent in patients not taking anti-platelet medication and when the time interval between arteriography and PTA exceeds 92 days. To minimise thrombotic arterial occlusion both diagnostic and therapeutic procedures should be performed simultaneously, but if a delay is unavoidable, patients should be treated with anti-platelet medication, which reduces the incidence of arterial occlusion.

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