Comparison of computed tomography and duplex imaging in assessing aortic morphology following endovascular aneurysm repair

BACKGROUND

Computed tomography (CT) has been used to assess patients following endovascular aneurysm repair to determine the need for secondary endoluminal or operative procedures. This prospective study compared CT and duplex imaging to evaluate aneurysm morphology following endoluminal aortic grafting.

METHODS

Twenty patients were evaluated at regular intervals following successful endoluminal aneurysm repair. CT and duplex scanning were compared in their ability to determine aneurysm and aortic diameter, the presence of perigraft extravasation (endoleaks) and technical defects in the endograft.

RESULTS

In 20 patients who were assessed 6 months after operation, duplex imaging identified four endoleaks (two early, two late; one proximal, three distal). In three cases, the aneurysm diameter progressively increased after operation. In patients with a thrombosed aneurysm sac, the aneurysm regressed at a median of 0.40 (range 0.13-0.8) cm per year. The CT findings were similar (median regression 0.43 (range 0-1.0) cm per year), although CT was unable to predict the site of the leak as accurately as duplex imaging. CT demonstrated that the diameter of the juxtarenal aorta increased following endografting.

CONCLUSION

Duplex imaging is a less invasive, less costly alternative to CT in the follow-up of patients after endoluminal aortic surgery. Increase in size of the aneurysm sac following endovascular aneurysm repair strongly suggests the presence of an endoleak.

Surgical decompression of thoracic outlet syndrome; is it a worthwhile procedure?

During a 20-year period from 1974 to 1994, 37 thoracic outlet decompressions were performed. There were 28 females and six males (ratio 5:1). The median age was 37 years (range 15-64). Symptoms were predominantly neurological in 29 limbs (78%), arterial in five limbs (14%) and venous in three limbs (8%). Limb pain and paraesthesia were the most common symptoms. Surgical decompression was performed via a supraclavicular approach in 24 limbs (65%) and a transaxillary approach in 13 limbs (35%). A cervical rib was excised in 21 limbs (57%), a first rib in 10 limbs (27%), a cervical and first rib in one limb (3%) and a cervical band in five limbs (13%). Arterial reconstruction was only required in three limbs (8%). There were a total of four complications (11%). The outcome of surgical decompression was assessed by using a questionnaire completed by the patient. Overall 27 patients (87%) felt that the operation was worthwhile. These results show that surgical decompression for thoracic outlet syndrome is a worthwhile procedure and is associated with relatively few complications.

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.

Surgical management of 671 abdominal aortic aneurysms: a 13 year review from a single centre

OBJECTIVE

To audit the results for abdominal aortic aneurysm (AAA) repair from a single centre over a 13 year period.

DESIGN

Retrospective survey.

SETTING

Vascular unit of a major teaching hospital.

MATERIALS

Six hundred and seventy-one consecutive patients divided into two groups: group A (1981-87) and group B (1988-93).

CHIEF OUTCOME MEASURES

Mortality rates, cause of death and major complications in patients undergoing elective, urgent and ruptured AAAs.

RESULTS

Elective repair was performed in 313 (47%) patients, urgent repair in 80 (12%) and emergency repair for rupture in 278 (41%). A vascular surgeon performed the procedure in 94% of patients. The overall mortality was 21 patients in the elective group (6.7%), 13 in the urgent group (16%) and 148 in the ruptured group (53%). Mortality rates have not fallen during the study period but more patients in group B had ischaemic heart disease. Sixty patients (9%) required further operative procedures on 66 occasions: 24 elective cases (8%), 8 urgent cases (10%) and 28 ruptured cases (10%). There were 23 deaths in these 60 patients (38%) who underwent re-operation (5 elective, 2 urgent and 16 ruptured). Major postoperative complications included cardiac events in 212 (32%) patients, respiratory failure in 202 (30%) and renal failure in 90 (13%). Major causes of death included cardiac disease in 67 patients (37%), cardiac disease with coagulopathy in 22 (12%) and cardiac disease with respiratory failure in 16 (9%). Logistic regression analysis showed that in the elective group, cardiac or renal failure were significantly associated with death; and in the ruptured group cardiac, respiratory or renal failure were significantly associated with death.

CONCLUSIONS

More high risk patients with ischaemic heart disease are undergoing AAA repair. Postoperative cardiac, respiratory or renal failure are significant causes of death in AAA patients.

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.

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.

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.

Elastase-induced matrix degradation in arterial organ cultures: an in vitro model of aneurysmal disease

PURPOSE

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, induction of endogenous metalloproteinases (MMPs), and development of a chronic inflammatory infiltrate. Despite intensive analysis of end-stage tissue, aneurysm pathogenesis remains obscure. The aim of this study was to develop an in vitro model of aneurysmal disease.

METHODS

Porcine aortic organ cultures were preincubated with pancreatic elastase before culture in standard conditions for up to 14 days. The extent of matrix degradation at various time points was determined by quantitative histologic estimation of collagen and elastin concentration. Endogenous metalloproteinase production within the tissue was quantified by gel enzymography and immunoblotting. A separate series of experiments was performed to investigate the effect of incorporating autologous leukocytes into the culture system.

RESULTS

Although exogenous elastase was removed after 24 hours, substantial degradation of the aortic extracellular matrix occurred in the subsequent 13 days in tissue culture. Analysis of samples preincubated with elastase (100 U/ml) for 24 hours before tissue culture demonstrated that elastin degradation occurred in a time-dependent manner (p < 0.001) and was not confined to the initial phase of exogenous elastase activity. Gelatin gel enzymography revealed a time-related production of metalloproteinases (55 to 250 kDa) within the aortic tissue. The presence of MMPs-1, 2, 3, and 9 was determined by immunoblotting. Immunohistochemistry identified the vascular smooth-muscle cell as the source of MMPs-1, 2, and 3. Addition of autogenous leukocytes to elastase-pretreated tissue initiated an inflammatory infiltrate within the aortic wall, which further enhanced both matrix degradation and MMP production (p < 0.001).

CONCLUSIONS

These data demonstrate that aortic samples pretreated with elastase before tissue culture undergo matrix degradation with MMP production and the development of an inflammatory infiltrate. These changes mirror the pathophysiological events within established aneurysms. It is suggested that this model may be useful in understanding early pathogenic events within aneurysmal tissue.

Oxygen free radical and cytokine generation during endovascular and conventional aneurysm repair

OBJECTIVES

Endovascular aneurysm repair has been proposed as a "minimally invasive" alternative to conventional aneurysm resection. One of the most important potential benefits of endoluminal surgery is the avoidance of aortic cross clamping, which may attenuate the ischaemia-reperfusion injury that complicates open aneurysm repair. This study aimed to quantify the metabolic response to both conventional and endovascular aortic surgery.

DESIGN

Prospective clinical study.

SETTING

University hospital.

METHODS

Femoral vein blood samples (pre-clamp, during aneurysm repair and 5 and 30 min post reperfusion) were obtained from 12 patients undergoing aortoaortic aneurysm repair, six by conventional transperitoneal inlay replacement (median age 71 years, median aneurysm diameter 5.8 cm), and six by endoluminal deployment of a straight endograft (median age 73 years, median aneurysm diameter 5.5 cm). All endovascular procedures were completed satisfactorily with no conversions to conventional surgery.

OUTCOME MEASURES

Venous blood samples were analysed for oxygen free radical (OFR) production using the quantifiable oxidation of IgG in plasma, and cytokine (IL-1 beta and TNF-alpha) generation by radioimmunoassay. [table: see text]

RESULTS

The results are given as median values with interquartile ranges:

CONCLUSIONS

These results suggest that the ischaemia-reperfusion response associated with conventional aneurysm surgery may be largely negated by endovascular techniques. This may have significant consequences as the generation of oxygen free radicals and cytokines have been implicated in the development of systemic organ failure following aortic surgery.

Angiogenesis in abdominal aortic aneurysms

OBJECTIVES

To determine the degree of neovascularisation in the wall of abdominal aortic aneurysms in comparison to atherosclerotic control aortas, and to correlate the angiogenic response with the extent of the cellular inflammatory infiltrate.

DESIGN

Histopathological study.

MATERIALS

Aortic samples were obtained from patients with abdominal aortic aneurysms and from atherosclerotic controls.

METHODS

Samples were stained with haematoxylin and eosin, and Miller's elastin and Van Gieson stain, EVG, and a monoclonal antibody specific to human endothelial cells. Within the aortic wall three histological regions were defined, the media, the adventitia and a transition zone. The number of capillary like, thin walled vessels were measured in each region, and the cellular infiltrate was quantified.

RESULTS

The number of newly formed vessels was increased in all layers of aneurysmal wall in comparison to control samples (p<0.001). The degree of neovascularisation correlated with the extent of the inflammatory infiltrate (rs=0.45, p<0.01).

CONCLUSIONS

This study demonstrated that abdominal aortic aneurysms are associated with a marked angiogenic response, which is related to the degree of inflammation within the aortic wall. It is hypothesised that anti-angiogenic agents may play a role in the medical management of aortic aneurysmal disease.

Percutaneous extraluminal (subintimal) recanalization of a brachial artery occlusion following cardiac catheterization

A 47-year-old woman presented with disabling right arm claudication 10 weeks after Sones cardiac catheterization via a brachial artery cut-down. A technique of extraluminal recanalization of the brachial artery occlusion, used to treat this patient, is described.

Endovascular repair of abdominal aortic aneurysm: an initial experience

Endovascular repair of abdominal aortic aneurysm (AAA) was attempted in ten patients over a 12-month period. Median age was 72 (range 61-82) years and median AAA diameter was 5.5 (range 5.2-6.0) cm. An aortoaortic (tube) graft was used in seven patients and a tapered aortoiliac reconstruction in three. There were two failures requiring conversion to open repair. Additional procedures included iliac artery angioplasty (two), coil embolization of an associated common iliac aneurysm (one) and femorodistal bypass (one). Median operating time was 162 (range 95-270) min and median blood loss was 1200 (range 800-2000) ml. Median hospital stay was 9 (range 5-21) days. Complications included death (one), reversible acute tubular necrosis (one) and prolonged ventilation (one). Postoperative evaluation with duplex ultrasonography and computed tomography demonstrated three perigraft leaks (two proximal and one distal). It is concluded that endovascular repair of AAA is feasible but is associated with significant complications and requires careful evaluation before widespread use.

Cloning and characterisation of the Schizosaccharomyces pombe rad32 gene: a gene required for repair of double strand breaks and recombination

A new Schizosaccharomyces pombe mutant (rad32) which is sensitive to gamma and UV irradiation is described. Pulsed field gel electrophoresis of DNA from irradiated cells indicates that the rad32 mutant, in comparison to wild type cells, has decreased ability to repair DNA double strand breaks. The mutant also undergoes decreased meiotic recombination and displays reduced stability of minichromosomes. The rad32 gene has been cloned by complementation of the UV sensitive phenotype. The gene, which is not essential for cell viability and is expressed at a moderate level in mitotically dividing cells, has significant homology to the meiotic recombination gene MRE11 of Saccharomyces cerevisiae. Epistasis analysis indicates that rad32 functions in a pathway which includes the rhp51 gene (the S.pombe homologue to S.cerevisiae RAD51) and that cells deleted for the rad32 gene in conjunction with either the rad3 deletion (a G2 checkpoint mutation) or the rad2 deletion (a chromosome stability and potential nucleotide excision repair mutation) are not viable.

Video-thoracoscopic lung biopsy in diagnosis of interstitial lung disease

Lung biopsy remains an important investigation in the diagnosis of diffuse interstitial lung disease despite improved diagnostic yield of high resolution computed tomography scanning. We describe 19 pulmonary wedge biopsies (13 men and 6 women) performed using videothoracoscopic technique. The median age of the patients was 56 years (range 32-72 years). All our patients were suspected to have diffuse interstitial lung disease and were referred for lung biopsy to obtain a histological diagnosis. Thoracoscopic wedge excisions were accomplished under general anaesthesia using high frequency jet ventilation and a percutaneous stapling device. A tissue diagnosis was obtained in all patients: 8 had cryptogenic fibrosing alveolitis, 3 had interstitial pulmonary fibrosis, 2 had emphysema, 2 had extrinsic allergic alveolitis, 2 had sarcoidosis, 1 had non-specific chronic inflammation, and 1 had pulmonary haemosiderosis. There were no operative deaths. There was one failure resulting in conversion to an open procedure. There were three complications: two air leaks and one effusion. Median postoperative hospital stay was 2 days (range 2-7 days). We conclude that videothoracoscopic wedge biopsy is a safe and effective procedure and should be recommended in patients who require a histological diagnosis of diffuse interstitial lung disease.

Trends in abdominal aortic aneurysms: a 13 year review

AIM

To assess changing trends of abdominal aortic aneurysms 1979-1991.

DESIGN

Retrospective study from the Leicestershire Health Authority.

RESULTS

727 patients with abdominal aortic aneurysm were treated. Of these 56.4% were admitted for elective repair and 43.6% presented with rupture. There was a significant increase in the number of ruptured aortic aneurysms over this period despite an increase in the number of elective repairs. The overall 30-day mortality of elective repair (including patients with symptomatic but non-ruptured aneurysms) was 8.8%. The overall 30-day mortality of ruptured aneurysms (including patients who were deemed medically too unfit for surgery) was 57.7%. There has been no significant change in elective and ruptured mortality over the study period. There was a significant increase in the median age of patients (69.5 yrs in 1979 to 74 yrs in 1991).

CONCLUSION

The increasing incidence of abdominal aortic aneurysms may reflect better diagnostic methods, greater clinical awareness of the condition and increase in the proportion of elderly people in the population.

Determination of haemophilia A carrier status from hair samples using polymerase chain reaction technique

The usefulness of intragenic restriction fragment length polymorphisms (RFLPs) for BclI, HindIII and XbaI, adapted for polymerase chain reaction (PCR), was tested for the detection of haemophilia A carrier status in the consultant of a family in which only haematological information was available on the inheritance of the trait. Hair follicles were used as the non-invasive source of DNA. The mother was found to be homozygous for BclI and heterozygous for HindIII sites, whereas her status as regards informativeness could not be established for XbaI. On the basis of HindIII RFLP, the daughter was found to be a carrier of the haemophilia trait. This was confirmed by sequencing the amplified intron 19 of the mother and the daughter. The RFLP for XbaI did not appear to be suitable for carrier detection using PCR due to the difficulty of establishing homozygosity or heterozygosity from the results of digestion of the amplified product.

Endovascular repair of abdominal aortic aneurysm: limitations of the single proximal stent technique

Endovascular repair of abdominal aortic aneurysm (AAA) has been performed using both a single proximal stent technique and a double (proximal and distal) stent method to anchor a graft in the aneurysm lumen. This study examined the effect of the single proximal stent technique on femoral artery blood flow, renal function and the occurrence of back-bleeding into the aneurysm sac in a canine model; eight dogs were used. Femoral artery blood flow and glomerular filtration rate were not affected by graft-stent insertion. Two graft-stent combinations failed to deploy in the correct position and led to graft thrombosis in one case. The six correctly positioned grafts all showed back-bleeding from around the distal end into the aneurysm sac. The single proximal stent technique for endovascular repair of AAA is inadequate and attention should continue to focus on a double (proximal and distal) stent method or a bifurcated system.