Friendly neck anatomy does not prevent neck-related adverse events after EVAR

OBJECTIVE

Life-long follow-up after EVAR is costly and burdensome to the patient. Follow-up should be stratified based on the risk of EVAR failure. Aneurysm neck is thought to be the single most important risk factor. This study investigated neck anatomy as a predictor of neck-related adverse events after EVAR.

METHODS

This retrospective single-center study included consecutive patients undergoing elective EVAR for infrarenal abdominal aortic aneurysms between 2011- 2016 (n=222) who were followed with yearly imaging until December 2020. Hostile neck was defined as neck length ≤15mm, width ≥28mm, angulation ≥60^°, calcification or thrombus ≥50% of circumference or conical neck based on preoperative computed tomography angiography. Neck-related adverse event was defined as aneurysm rupture, any neck-related re-intervention or type 1a endoleak during follow-up.

RESULTS

Ninety (41%) patients had hostile neck, and 132 (59%) had friendly neck. There were no differences in 30-day mortality (1% vs. 1%, p=0.78), major adverse events (20% vs. 16%, p=0.43) or re-interventions during the hospital stay (8% vs 4%, p=0.20) between patients with hostile and friendly neck. Estimated survival at 1 year was 89±3% for hostile neck and 95±2% for friendly neck patients (p<0.01). Five-year survival estimates were 51±6% and 66±4%, respectively. Aneurysm-related mortality was higher after six years in patients with hostile neck (p<0.01). Twenty-four patients (11%) suffered neck-related adverse events with mean time-to-event of 3.3±2.8 years, there were no differences between the groups stratified by neck anatomy. Incidentally, preoperative aneurysm diameter was found to be an independent risk factor for neck-related adverse events and aneurysm-related mortality; 53 patients (24%) had aneurysm diameter ≥70mm, which was associated with nearly four-fold risk of neck-related complications during the follow-up.

CONCLUSIONS

Friendly neck anatomy may not protect from neck-related adverse events after EVAR in the long-term. Especially patients with large aneurysms should be followed closely.

Accuracy of Digital Videodensitometry in Quantitating Contrast Medium Concentration

To evaluate the accuracy of digital videodensitometric technique in directly quantitating concentration of contrast medium, iohexol 300 mg I/ml was injected into a 2-mm-diameter plastic tube, in which clean water was circulated at a 190 ml/min flow, for digital subtraction angiography. Altogether 27 injections were performed with 3, 4 and 5 ml volumes at 3-, 4- and 5-ml/s flows of the contrast medium. A time-density curve was achieved by selecting a “vessel” region of interest (ROI) and a background ROI. Then, a frame corresponding to the maximum opacification of the contrast medium could be calculated. Finally, the average density and the time to peak density of the contrast medium were obtained. The average density was statistically higher (p < 0.01) with 5 ml/s flow than with 4- and 3-ml/s flows. Times to peak density reduced as injection flows or volumes increased. The results support the conclusion that digital videodensitometric technique is an accurate method for quantitation of contrast medium concentration during angiography. The angiographic opacification may be improved by injecting the iodine contrast medium with higher flows or larger volumes.

Evaluation of Heart Size and Pulmonary Vasculature

Inter- and intraobserver variation and diagnostic accuracy in estimation of heart size and pulmonary vasculature were evaluated for conventional film-screen technique and image intensifier photofluorography. Interpretation of 218 p.a. and lateral chest films by both imaging techniques was performed independently by 4 readers. Heart size relative to body surface area measured from the plain chest films was used as the reference in cardiac size determination. Overall diagnostic accuracies of conventional radiography and image intensifier photofluorography for cardiomegaly were close to each other, 0.70 vs 0.68, respectively. Specificity of film-screen radiography was better than that of photofluorography (0.92 vs 0.84, p <0.05). Interobserver agreement was poor both in assessment of the heart size and pulmonary vasculature (range of kappa coefficients 0.18–0.59) while the intraobserver consistency (kappa coefficients 0.60–0.85) was good to excellent. The results suggest a limited usefulness of visual assessment of heart size and pulmonary vasculature in chest roentgenographs.

Large-Image Intensifier Photofluorography and Conventional Radiography in Pulmonary Emphysema

Large-screen image intensifier (II) photofluorography was compared with full-size screen-film chest radiography in the diagnosis of pulmonary emphysema in 84 patients. Photospot films and conventional radiographs were interpreted independently by three radiologists. Computed tomography (CT) was used as an independent reference technique, and diagnostic performance of chest radiography in various CT patterns of emphysema was evaluated. The difference in diagnostic sensitivity for emphysema in favor of conventional chest radiography over photofluorography (0.65 versus 0.56) was statistically significant (p<0.05). Specificity of the imaging modalities was equal: 0.78 in full-size films and 0.77 in photospot films. All CT patterns of emphysema had great false negative response rates in chest radiography, which is an inaccurate technique for the diagnosis of emphysema. CT is required for reliable radiologic evaluation of emphysema.

Percutaneous Transluminal Laser Angioplasty

The progress in percutaneous transluminal laser angioplasty (PTLA) over the past two years is presented. The technical development includes the application of new equipments to laser sources, delivery systems and monitors. We review new experimental research in rapidly establishing animal models and human postmortem specimens, as well as efforts to select adequate wave length and irradiation time for laser energy with suitable infusion media. A summary of clinical trials is given on expanding usage, complication rates and long-term patency of PTLA. The current trends in PTLA respecting guide wire assisted balloon angioplasty and other recanalization methods are described.

Assessment of myocardial perfusion with MRI using a modified dual bolus method

Quantification of regional myocardial blood flow (rMBF) with first-pass magnetic resonance imaging (FP-MRI) requires two contrast agent injections (dual bolus technique), inducing error in the determined rMBF if the injections differ. We hypothesize that using input and residue curves of the same injection would be more reliable. We aim to introduce and evaluate a novel method to correct the high concentration arterial input function (AIF) for determination of rMBF. Sixteen patients with non-Hodgkin's lymphoma were examined before and after chemotherapy. The input function was solved by correcting initial high concentration AIF using the ratio of low and high contrast AIF areas, normalized by corresponding heart rates (modified dual bolus method). For comparison, the scaled low contrast AIF was used as an input function (dual bolus method). Unidirectional transfer coefficient K(trans) was calculated using both methods. K(trans)-values determined with the dual bolus (0.81 ± 0.32 ml g(-1) min(-1)) and modified dual bolus (0.77 ± 0.42 ml g(-1) min(-1)) methods were in agreement (p = 0.21). Mean K(trans)-values increased from 0.76 ± 0.43 to 0.89 ± 0.55 ml g(-1) min(-1) after chemotherapy (p = 0.17). The modified dual bolus technique agrees with the dual bolus technique (R2 = 0.899) when the low and high contrast injections are similar. However, when this is not the case, the modified dual bolus technique may be more reliable.

PTFE bypass or thrupass for superficial femoral artery occlusion? A randomised controlled trial

Early results of a thrupass endograft in the treatment of femoral lesions are promising. Less morbidity and better cost-effectiveness are suggested to be achieved in the treatment of chronic lower limb ischaemia with endovascular treatment compared to surgical treatment.

PATIENTS AND METHODS

This randomised multicentre trial aimed to enroll a group of 60+60 patients for the treatment of 5-25-cm occlusions of superficial femoral artery (SFA) to be followed up for 3 years. Patients were treated either with endoluminal PTFE thrupass (WL Gore & Ass) or with surgical polytetrafluoroethylene (PTFE) bypass to proximal popliteal artery. Primary patency at 3 years was scheduled to be the primary end-point and secondary patency, functional success, costs and quality of life the secondary end-points.

RESULTS

A sample of 100 consecutive SFA occlusions in one of the centres revealed that only 4% of the lesions were amenable for the study. The trial was prematurely terminated due to the results of an interim analysis at the time when 44 patients were recruited: the 1-year primary patency (excluding technical failures) was 48% for thrupass and 95% for bypass (p=0.02). The patency difference in favour of surgical bypass over endovascular thrupass was also sustained after completion of 1-year follow-up, the primary patencies being 46% and 84% at 1 year with grossly equilinear life-table curves thereafter (p=0.18), respectively. The corresponding secondary patencies were 63% and 100% (p=0.05) when excluding technical failures and 58% and 100% (p=0.02) according to intention-to-treat analysis. Secondary outcomes were thus not analysed.

CONCLUSION

Treatment of SFA occlusions (TASC IIB and C or Imelda Ia and II) should be done by PTFE bypass rather than by PTFE thrupass, as thrupass is connected with worse early outcome. These results represent only a small category of femoral disease.

Transfection of oocytes and other types of ovarian cells in rabbits after direct injection into uterine arteries of adenoviruses and plasmid/liposomes

Transfection of oocytes should be avoided in somatic gene therapy. However, several viral vectors including adenoviruses can transfect zona-pellucida-free eggs in vitro. During early stages of development, oocytes of postnatal ovaries lack the zona pellucida. Therefore, they may be susceptible to gene transfer and unintended toxic effects. The purpose of this study was to see whether the injection of adenoviruses (1 x 10(10) PFU) or plasmid (500 microg)/DOTMA:DOPE (1:2) liposomes directly into uterine arteries in pregnant rabbits leads to transfection of oocytes and other types of ovarian cells. LacZ and herpes simplex virus thymidine kinase (HSV-TK) were used as transgenes. It was found that both adenovirus and plasmid vectors transfected oocytes at the primordial and primary follicle stage when they were not protected by the zona pellucida, whereas no transfection was seen in oocytes surrounded by the zona pellucida. Efficient transfection of corpus luteum and granulosa cells was also detected by adenoviral and plasmid vectors. Transfection of oocytes and other ovarian cells was verified by X-gal staining and laser microdissection, followed by PCR analysis. HSV-TK gene transfer, followed by ganciclovir treatment, led to destruction of a significant number of oocytes, whereas HSV-TK gene transfer alone did not lead to toxic effects. It is concluded that the presence of a high concentration of adenovirus or plasmid vectors via the uterine artery may lead to transfection of zona-pellucida-free oocytes and other ovarian cells.

Endovascular treatment of aortic aneurysms in Finland: the first four years' experience

BACKGROUND AND AIMS

In this study the results of endovascular treatment of aortic aneurysms in Finland are presented and compared to the results of the Eurostar registry.

MATERIAL AND METHODS

A total of 229 patients with aortic aneurysm were treated in five different Finnish centres during 1996-2000. The data of these patients were collected prospectively by surgeon or interventional radiologist involved. During the same period of time 2464 patients were registered in the Eurostar registry.

RESULTS

The procedure was performed successfully in 97% of patients in Finland, and the 30-day mortality was 0,9%. A graft limb thrombosis was detected in 9% of the patients in Finland. A permanent primary endoleak at the first 30-day control was seen in 23 patients (10%). During the follow-up 17 secondary endoleaks (7%) were detected. A secondary intervention was necessary in 26% of the patients. Three patients (1.3%) had late rupture of the abdominal aortic aneurysm.

CONCLUSIONS

According to the Finnish short-time results, endovascular treatment of aortic aneurysms is safe and associated with relatively low morbidity and mortality. The mid-term results are more disappointing with relatively many graft thromboses and endoleaks, and a frequent need of secondary interventions.

Results of infrainguinal bypass surgery: an analysis of 263 consecutive operations

BACKGROUND AND AIMS

The purpose of this clinical study was to assess the success of infrainguinal revascularization in the treatment of lower limb ischaemia.

MATERIAL AND METHODS

226 consecutive patients underwent 263 femoropopliteal (n = 194) or femorodistal (n = 69) bypass operations during 1988-1996 at a university hospital. Records of all patients were reviewed. Late control visits including clinical and colour doppler ultrasound examinations were programmed for 109 patients. Initial success, primary and secondary patencies, limb salvage and survival rates were determined and factors affecting outcome were analysed in various patient categories.

RESULTS

Initial success rate was 92% (243/263). The primary and secondary patencies were 70/83% and 52/63% at one and five years, respectively. The corresponding limb salvage rates for patients with chronic critical ischaemia were 82% and 77%. The number of diseased vessels in the treated limb correlated negatively with the primary patency. Advanced age did not affect primary patency or limb salvage rates. Diabetes and the use of distal revascularizations were independent predictors of poorer limb salvage. Diabetes and renal insufficiency proved to shorten life expectancy.

CONCLUSIONS

Infrainguinal revascularizations are effective regardless of patient's age. The extent of atherosclerotic changes in the operated limb, diabetes and renal insufficiency are factors affecting outcome.

Angiographically guided utero-placental gene transfer in rabbits with adenoviruses, plasmid/liposomes and plasmid/polyethyleneimine complexes

We examined the feasibility of gene transfer to rabbit placenta using adenoviruses, plasmid/liposomes and plasmid/polyethyleneimine (PEI) complexes. Pregnant New Zealand White rabbits (n = 17) were anesthetized and local gene transfer was done via a catheter inserted in uterine arteries under direct angiographic control. Either nuclear targeted LacZ adenoviruses (1.0 x 10(10) p.f.u.), nuclear targeted LacZ plasmid (500 microg)/liposome (DOTMA:DOPE 1:1) complexes or nuclear targeted LacZ plasmid (250 microg)/PEI (25 kDa) complexes (charge ratio +/-4) were used. Animals were killed 3 days later and detection of the transgene expression was done by X-gal staining and RT-PCR. Adenovirus-mediated gene transfer resulted in a high transfection efficiency (34 +/- 10%) in placental trophoplastic cells. Very little, if any, transfection was seen in fetal membranes. Plasmid/liposomes and plasmid/PEI complexes led to a very low (<0.01%) transfection efficiency in trophoblastic cells, but some transfection was seen in fetal membranes. A total of 25 fetuses were analyzed for the presence of transgene at the time of death. In most fetuses expression of the LacZ gene was below the sensitivity of the X-gal staining, but expression was detected by PCR in 50%, 50% and 42% of the analyzed fetuses after adenoviral, plasmid/PEI and plasmid/liposome gene transfer, respectively. No major inflammatory changes were present in the transfected placentas as analyzed by general histology and macrophage- and T cell-specific immunostainings. We conclude that catheter-mediated intravascular gene transfer with adenoviruses can be used for the transfection of placental trophoplastic cells, but plasmid complexes are inefficient for this purpose. However, selective angiographically guided gene transfer also led to leakage of the vector to fetuses. Therefore, if gene therapy is developed for the treatment of placental disorders, the gene-vector combination should not be harmful to the fetus and the expression of the transgene should only occur in placenta.

Disc degeneration and bone density in monozygotic twins discordant for insulin-dependent diabetes mellitus

The effects of insulin-dependent diabetes mellitus on bone density and connective tissue degeneration have theoretical interest and practical relevance. Several experimental studies in animals have demonstrated the harmful effects of insulin deficiency on connective tissues. However, clinical studies in humans have produced somewhat contradictory results, most likely due to difficulties controlling for general degeneration and factors associated with diabetes. In nine pairs of monozygotic twins discordant for insulin-dependent diabetes mellitus, we compared femoral and lumbar bone mineral density (assessed by dual-energy x-ray absorptiometry) and spinal degeneration (assessed by magnetic resonance imaging). The bone densities were, on average, 0.1-0.3% lower (p = 0.87-0.96) in diabetic patients. However, after controlling for smoking, we found that the bone density in the femoral neck was 2.5% (0.025 g/cm2) lower in diabetic individuals than in their twins (p = 0.09). The five magnetic resonance imaging parameters used to evaluate disc degeneration did not differ between diabetic patients and their twins. In conclusion, our results provide no evidence that insulin-dependent diabetes mellitus has any major effect on bone density or disc degeneration.

Catheter-mediated vascular endothelial growth factor gene transfer to human coronary arteries after angioplasty

Blood vessels are among the easiest targets for gene therapy. However, no data are available about the safety and feasibility of intracoronary gene transfer in humans. We studied the safety and efficacy of catheter-mediated vascular endothelial growth factor (VEGF) plasmid/liposome (P/L) gene transfer in human coronary arteries after percutaneous translumenal coronary angioplasty (PTCA) in a randomized, double-blinded, placebo-controlled study. The optimized angioplasty/gene delivery method was previously shown to lead to detectable VEGF gene expression in human peripheral arteries as analyzed from amputated leg samples. Gene transfer to coronary arteries was done with a perfusion-infusion catheter, using 1000 microg of VEGF or beta-galactosidase plasmid complexed with 1000 microl of DOTMA:DOPE liposomes. Ten patients received VEGF P/L, three patients received beta-galactosidase P/L, and two patients received Ringer lactate. Gene transfer to coronary arteries was feasible and well tolerated. Except for a slight increase in serum C-reative protein in all study groups, no adverse effects or abnormalities in laboratory parameters were detected. No VEGF plasmid or recombinant VEGF protein was present in the systemic circulation after the gene transfer. In control angiography 6 months later, no differences were detected in the degree of coronary stenosis between treatment and control groups. We conclude that catheter-mediated intracoronary gene transfer performed after angioplasty is safe and well tolerated and potentially applicable for the prevention of restenosis and myocardial ischemia.

Computed tomography findings 4 years after surgical management of lumbar spinal stenosis. No correlation with clinical outcome

STUDY DESIGN

A prospective, cross-sectional study of the correlation between postoperative computed tomography findings and patients' clinical outcomes approximately 4 years after laminectomy for lumbar spinal stenosis.

OBJECTIVES

To evaluate clinical and radiologic characteristics and their relation to each other.

SUMMARY OF BACKGROUND DATA

The goal of surgical management for lumbar spinal stenosis is to decompress the stenotic area determined in radiologic examinations to relieve pressure on the neurovascular structures. However, the success of this decompression very rarely has been confirmed by postoperative radiologic imaging or compared with clinical outcome.

METHODS

Postoperative computed tomography was performed on 191 patients. The findings were classified as "no stenosis," "central stenosis," "lateral stenosis," or "central-lateral stenosis." Postoperative instability of the lumbar spine was investigated by functional radiography. Clinical status was assessed by clinical examination. Subjective disability was assessing using the Oswestry questionnaire, and severity of pain using the visual analog scale. Walking capacity was evaluated by the tread-mill test.

RESULTS

Radiologic studies revealed postoperative stenosis in 123 patients (64%). Small differences between the computed tomography groups were shown for the Oswestry score, but not for walking distance. Clinical signs, severity of pain, and radiologic instability were very similar for all computed tomography groups.

CONCLUSIONS

Postoperative radiologic stenosis was very common in patients operated on for lumbar spinal stenosis, but this did not correlate with clinical outcome. The clinician must be cautious when reconciling clinical symptoms and signs with postoperative computed tomography findings in patients operated on for lumbar spinal stenosis.

Adenovirus-mediated gene transfer to lower limb artery of patients with chronic critical leg ischemia

Arterial gene transfer offers a promising new approach for the treatment of vascular disorders. However, no data are available about the gene transfer efficiency in human arteries in vivo. The aim of this study was to evaluate the safety and feasibility of catheter-mediated adenoviral gene transfer in human peripheral arteries. Ten patients (8 females, 2 males, mean age 80 +/- 8 years) suffering from chronic critical leg ischemia with a prior decision for amputation were recruited in the study. Gene transfer was performed in eight patients in conjunction with a conventional percutaneous transluminal angioplasty, using a perfusion coil balloon catheter. Two patients served as controls. Increasing concentrations of replication-deficient adenoviruses (titers from 1 x 10(8) to 4 x 10(10) PFU) containing a nuclear-targeted beta-galactosidase marker gene were administered into the arteries over 10 min via the catheter. Amputations were performed 20 to 51 hr after the procedures and gene transfer efficiency was evaluated in the transduced arteries using X-Gal staining for beta-galactosidase activity. Beta-galactosidase gene transfer was well tolerated and no adverse tissue responses or systemic complications were observed in any of the patients. Gene transfer was successful in six of the eight patients. Gene transfer efficiency varied between 0.04 and 5.0% of all arterial cells. Transgene expression was detected in smooth muscle cells, endothelial cells, and macrophages and in tunica adventitia. However, transgene activity was not evenly distributed in the arterial wall and no transgene activity was found beneath advanced atherosclerotic lesions. The safety and feasibility of in vivo gene transfer by adenoviral vectors to human peripheral arteries were established. Although improvements are still required in gene transfer efficiency, these findings suggest that adenoviruses can be used to deliver therapeutically active genes into human arteries.

Subclinical cerebral complications after coronary artery bypass grafting: prospective analysis with magnetic resonance imaging, quantitative electroencephalography, and neuropsychological assessment

OBJECTIVE

To analyze the frequency and severity of subclinical cerebral complications associated with coronary artery bypass grafting (CABG).

DESIGN

A prospective controlled study using preoperative and postoperative magnetic resonance imaging (MRI) of the brain, quantitative electroencephalography (QEEG), and detailed neuropsychological and neurologic examinations as potentially sensitive indicators of subclinical cerebral injury associated with CABG.

SETTING

Multimodality evaluation in a tertiary care unit (Kuopio University Hospital, Kuopio, Finland).

PATIENTS

Thirty-eight patients undergoing elective CABG and 20 control patients undergoing other major vascular surgery, mostly operations on the abdominal aorta.

MAIN OUTCOME MEASURES

Coronary artery bypass grafting-associated cerebral complications assessed preoperatively and postoperatively by brain MRI, QEEG, detailed neurologic examination, and a neuropsychological test battery that evaluates cognitive functions in major areas known to be vulnerable to organic impairment (learning and memory, attention, flexible mental processing, and psychomotor speed).

RESULTS

There were no major neurologic complications. A mild hemisyndrome developed in 1 patient who underwent CABG and in 1 control patient. Overall, there was no decline in mean cognitive performance 3 months after surgery. Electroencephalographic slowing of 0.5 Hz or more in at least 2 channels occurred in 11 patients who underwent CABG and in 1 control patient (P=.03). The postoperative brain MRI scan revealed new small ischemic lesions in 8 patients (21%) in the CABG group but in none of the control group (P=.03). These new cerebral MRI lesions did not explain deterioration in neuropsychological test performance or the QEEG slowing.

CONCLUSIONS

Coronary artery bypass grafting causes more QEEG alterations and small ischemic cerebral lesions that are detectable by MRI than does other major vascular surgery. The effect is mainly subclinical, because no statistically significant deterioration in mean neuropsychological test performance was detected.

Stent grafting for abdominal aortic aneurysms in Finland--a feasibility study

BACKGROUND AND AIMS

Endovascular repair of abdominal aortic aneurysms (AAA) is a feasible procedure in selected patients. In order to assess how many AAAs are suitable for such a procedure, a survey has been conducted in Helsinki, Kuopio, and Tampere University Hospitals.

MATERIAL AND METHODS

AAAs having a maximum diameter of 45 mm or more at ultrasonography were included for further evaluation and assessment by angiography and/or spiral CT angiography to determine the length and width of infrarenal aneurysmal neck as well as the dimensions of the distal abdominal aorta and iliac arteries.

RESULTS

Among a total of 75 patients with AAA examined in three centres, ultrasonography overestimated the size of the aneurysm in 12 cases that were demonstrated by angiography and CT to have a diameter of less than 45 mm. Among those patients with larger aneurysms, 17 (27%) were suitable for endovascular repair. Stent grafting has been performed in 10 patients until May, 1997. Perigraft leakage occurred in one patient who required the insertion of an additional collar stent graft.

CONCLUSIONS

Large numbers of suitable patients are not easy to find but, by performing joint screening in Finland, epidemiological data on suitable aneurysms and improving co-operation between centres can be achieved. Therefore, it would be wise to centralise endovascular repair of AAA.

Lifetime exercise and disk degeneration: an MRI study of monozygotic twins

Participation in some competitive sports has been shown to increase disk degeneration; however, the long-term effects of recreational physical activities are unclear. We investigated the effects of endurance exercise and power sports on disk degeneration in monozygotic male twins with contrasting lifetime exercise histories. The effects of endurance exercise were studied in 22 discordant twin pairs (mean lifetime frequencies of 3.9 vs 1.1 times/wk), and the effects of power sports were investigated in 12 discordant pairs (2,300 vs 200 h of weightlifting). The age range of the twins was from 35 to 69 yr. No differences in MRI findings between co-twins discordant for endurance exercise were found at any of the spinal regions. Subjects with more power sport involvement had greater disk degeneration in the T6-T12 region (P < 0.03), but similar findings were not present in the lumbar spine. Controlling for recalled back injuries, occupational loading, smoking, and driving did not significantly affect the results. No signs of beneficial or harmful effects of lifetime endurance exercise on disk degeneration were seen. Increased power sport participation was associated with slightly greater disk degeneration in the lower thoracic spine, but not in the lumbar spine.

The association of trunk muscle cross-sectional area and magnetic resonance image parameters with isokinetic and psychophysical lifting strength and static back muscle endurance in men

The relationship between trunk muscle morphology as measured on transverse magnetic resonance images and isokinetic lifting, psychophysical lifting, and static back muscle endurance testing was examined in 110 men, ages 35-67 years (mean, 48 years), who had been chosen based on their exposure to a wide variety of occupational and leisure-time physical activities. The computed T2-relaxation times and the T2-weighted and proton density-weighted signal intensities of the erector spinae, quadratus lumborum, and psoas major muscles had almost no association with any of the strength tests. The cross-sectional areas of the muscles had good correlations with isokinetic lifting strength (r = 0.46-0.53). They did not correlate well with psychophysical lifting and static back muscle endurance. Other characteristics or neurological or psychological factors may have more influence on those tests.

Movement disturbances of the lumbar spine and abnormal back muscle electromyographic findings in recurrent low back pain

STUDY DESIGN

A cross-sectional analysis was done of patients with recurrent low back pain referring to the lower limbs.

OBJECTIVES

To analyze dynamic radiographs of forward and backward bending of the lumbar back and to determine, using routine neurophysiologic measurements, the functional state of the lower nerve roots in patients with recurrent low back pain radiating to the lower limbs.

METHODS

Clinical and neurophysiologic studies showed eight of the 108 patients with low back pain to have ventral root impingement at either L5 or S1 level. The remaining 100 patients, 56 women and 44 men (mean age, 37.6 years; range, 17-62 years), made up the study group for continuing investigation. History of low back pain ranged from 4 months to 20 years.

RESULTS

Disturbed intervertebral movement was found in 51 of 100 patients. Twenty-seven percent had L5 or L4 anterolisthetic hypermobility, and 35% had L4 or L3 vertebral retrolisthesis. Vaguely delineated radiating sensations in the lower limbs were common (62%). Back muscle electromyographs were mostly (86%) normal in patients whose low back pain was localized. Conversely, almost three-fourths of those experiencing radiating or referred pain had abnormal electromyographs, consistent with a mild degree of axonal damage in the posterior branch of the lumbar nerve root innervating the medial paraspinal muscles. This finding was most common among patients with retrolisthesis and simultaneous degenerative changes.

CONCLUSIONS

Evaluation of low back pain should include tests for degenerative retrolisthesis, especially in patients experiencing radiating sensations with no evidence of root impingement, because abnormal electromyographic findings showing denervation of the paraspinal muscles was most common in patients with degenerative retrolisthesis. To improve the functional support of the lumbar region, rehabilitation should be directed to the medial back muscles because they provide the most effective support for intervertebral motion and because mild disturbances appear to be associated with their innervation in recurrent low back pain.

Formation of PCDD/PCDF : Effect of fuel and fly ash composition on the formation of PCDD/PCDF in the co-combustion of refuse-derived and packaging-derived fuels Multivariate analysis

One option of recycling used contaminated packaging is to recover its high energy content. This can be performed in a normal multi-fuel power plant by co-combustion of packaging-derived fuel (PDF) or refuse-derived fuel (RDF) with fossil fuels, such as coal or peat. This work includes the results of 17 co-combustion tests and an evaluation of the results by the Principal Component Analysis (PCA) and the Partial Least Squares Projections to Latent Structures (PLS).PCA and PLS calculations showed that especially Pb, but also Cr, and Cu correlated with lower chlorinated furans (PCDFs) in the fly ash. Correlation between Sn and lower chlorinated dioxins (PCDDs) in the fly ash was also noticed. CO and PAH emission in the flue gas correlated with total PCDD/Fs in the flue gas. In a real full-scale combustion process, a single parameter in fuel, flue gas or a combustion parameter did not provide a guide to PCDD/F formation or to a level of the total PCDD/F emission, but correlations between different parameters and PCDD/Fs could be found. Although PDFs and RDF had catalytic heavy metals and chlorine, the co-combustion results showed that they can be co-combusted with peat and coal in a fluidized-bed boiler at least up to 26 % with very low total PCDD and PCDF emissions.

1995 Volvo Award in clinical sciences. Determinants of lumbar disc degeneration. A study relating lifetime exposures and magnetic resonance imaging findings in identical twins

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

To investigate the effects of lifetime exposure to commonly suspected risk factors on disc degeneration using magnetic resonance imaging, and to estimate the effects of these suspected risk factors relative to age and familial aggregation, reflecting genetic and shared environmental influences.

SUMMARY OF BACKGROUND DATA

Structural and biochemical changes associated with disc degeneration are suspected as the underlying conditions of many back-related symptoms. Little is known about the determinants of disc degeneration.

METHODS

Based on lifetime discordance in suspected environmental risk factors for disc degeneration, 115 male identical twin pairs were selected. An in-depth interview was conducted of occupational and leisure time physical loading, driving, and smoking. Disc degeneration was evaluated using observational and digital magnetic resonance imaging assessment methods.

RESULTS

Heavier lifetime occupational and leisure physical loading was associated with greater disc degeneration in the upper lumbar levels (P = 0.055 - 0.001), whereas sedentary work was associated with lesser degeneration (P = 0.006). These univariate associations did not reach statistical significance in the lower lumbar region. In multivariate analyses of the upper lumbar levels, the mean job code explained 7% of the variability in observational disc degeneration scores; the addition of age explained 16%, and familial aggregation improved the model such that 77% of the variability was explained. In the lower lumbar levels, leisure time physical loading entered the multivariate model, explaining 2% of the variability. Adding age explained 9%, and familial aggregation raised the variability in disc degeneration scores explained to 43%.

CONCLUSIONS

The present study findings suggest that disc degeneration may be explained primarily by genetic influences and by unidentified factors, which may include complex, unpredictable interactions. The particular environmental factors studied, which have been among those most widely suspected of accelerating disc degeneration, had very modest effects.

Imaging of carotid artery stenosis: clinical efficacy and cost-effectiveness

PURPOSE

To determine the most accurate, safe, and cost-effective imaging protocol for selecting patients for carotid endarterectomy.

METHODS

The actual costs of carotid angiography, ultrasound, and MR angiography were calculated. The diagnostic accuracy with different confidence levels was assessed for carotid ultrasound and MR angiography in 45 patients. The cost-effectiveness and theoretical impact on patient outcome of hypothetical screening models were compared.

RESULTS

Ultrasound before angiography is more effective and considerably cheaper than performing angiography in all patients presenting with transient ischemic attacks ($25 216 versus $48 708 imaging costs per one prevented stroke). When the more costly MR angiography was used to select patients for angiography the slightly higher diagnostic accuracy did not result in a greater number of prevented strokes. As the only preoperative scrutiny, the combination of ultrasound and MR angiography would have resulted in a greater number of prevented strokes than invasive angiography (27.9 versus 23.3) but at the expense of unnecessary surgery (6.6% of all surgeries).

CONCLUSIONS

Ultrasound followed by confirmatory angiography is a cost-effective way to image patients suspected of carotid artery stenosis. MR angiography may become cost effective and lead to a better final patient outcome only when it can reliably replace invasive angiography as the preoperative examination.

Carbon dioxide in vascular imaging and intervention

Angiography with iodinated contrast agents is bound up with the risks of contrast-induced nephrotoxicity and hypersensitivity, which led to the idea of using carbon dioxide (CO2) gas as a negative contrast medium to eliminate these drawbacks. During the last decade, refinements and experiences have proved carbon dioxide digital subtraction angiography (CO2-DSA) to be an accurate, safe, and clinically promising vascular imaging modality, with the advantages of no hypersensitivity and no nephrotoxicity as well as minimal patient discomfort. In this article, we have reviewed the history, physical and chemical aspects, techniques, and pathophysiologic changes with the use of CO2-DSA as well as some clinical trials. Applications of CO2 gas in vascular interventions and other imagings, and the advantages and limitations of using CO2 gas in DSA are also discussed.

Thoracic outlet syndrome--a functional disturbance of the thoracic upper aperture?

We describe a young woman with typical neurovascular symptoms of thoracic outlet syndrome (TOS). A three-dimensional computerized scan showed a "dislocation" of the first rib at the costotransverse joint. The patient responded to a conservative approach to treatment. The patient presented here demonstrates the functional compromise of the upper thoracic aperture that is frequently seen in young women.

Observer variability in the assessment of disc degeneration on magnetic resonance images of the lumbar and thoracic spine

STUDY DESIGN

Intraobserver and interobserver reproducibility study.

OBJECTIVE

This study investigates the variability in the interpretation of degenerative disc findings using magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

Magnetic resonance imaging has been used for years in clinical diagnostics, primarily to investigate disc herniation and spinal stenosis. Less attention has been paid to other disc findings and their assessment reliability.

METHODS

Three independent readers evaluated magnetic resonance images of the lumbar and the lower and middle thoracic spines of 122 subjects by grading 12 aspects of the intervertebral discs and adjacent endplates using written definitions and example images. Images of 20 subjects were reevaluated for the assessment of intraobserver agreement.

RESULTS

Agreement was highest in the lower lumbar and poorest in the middle thoracic spine. Intraobserver agreement was generally fair to excellent for almost all variables in the lumbar and lower thoracic spine (most intraclass correlation and kappa coefficients for these regions were above 0.70). Interobserver agreement was notably lower than intraobserver agreement, except for osteophytes and endplate defects in some regions.

CONCLUSIONS

Intraobserver agreement in the evaluation of disc degeneration was at an acceptable level, in general, in the lumbar and lower thoracic spine. However, assessments were substantially more variable between readers, which limits comparisons of evaluations between different readers.

Magnetic resonance imaging findings and their relationships in the thoracic and lumbar spine. Insights into the etiopathogenesis of spinal degeneration

STUDY DESIGN

Descriptive epidemiologic study about magnetic resonance imaging findings in the spine.

OBJECTIVES

To describe the prevalence of magnetic resonance imaging findings in a general population at spinal levels T6-S1, and to examine the relationships of these findings within each spinal level and between levels.

SUMMARY OF BACKGROUND DATA

The prevalence of specific findings and the associations between findings and spinal levels can provide general insights into the etiopathogenesis of spinal degeneration.

METHODS

Subjects consisted of 232 men from a population sample (mean age 49.3 years). Signal intensity, disc bulging, disc herniation, and endplate irregularities were among 11 findings assessed from magnetic resonance images.

RESULTS

The disc signal intensities were assessed to be lowest in the lumbar and middle thoracic regions. Disc bulging and disc height narrowing were most common in the lower levels of both the thoracic and lumbar regions. All magnetic resonance imaging findings except herniations and endplate irregularities were clearly associated with age. Osteophytes were most highly associated with disc bulging in levels T6-L3, and with endplate irregularities in the lower lumbar levels. Disc herniations were not consistently associated with any other findings. The disc levels that most highly correlated are grouped as follows: T6-T10, T10-L4, and L4-S1.

CONCLUSIONS

With the exception of endplate irregularities and herniations, the magnetic resonance imaging findings appeared to be associated with the same pathogenic process. The interaction of mechanical factors and spinal structures varies between spinal levels, and the degeneration common in the lower parts of the thoracic and lumbar spine could be an outcome of vulnerability for torsional forces. Some gross guidelines for grouping findings can be drawn from disc level correlations.

Breathing pattern and gas exchange in emergency and elective abdominal surgical patients

OBJECTIVE

To evaluate the effects of intra-abdominal surgical emergency on breathing pattern and gas exchange and compare it with the changes induced by elective abdominal surgery.

DESIGN

Prospective clinical study.

SETTING

Abdominal surgical departments in a university hospital.

PATIENTS

Patients operated for intra-abdominal emergency (n = 10, EAS), elective upper abdominal (n = 19, UAS).

MEASUREMENTS AND RESULTS

Breathing pattern and gas exchange were measured with a respiratory inductive plethysmograph and a gas exchange monitor. EAS patients had pre-operatively a classical rapid shallow breathing pattern and increased ventilatory demand due to increased energy expenditure. The operation improved the breathing to normal pattern (frequency, 26 +/- 5/min and 17 +/- 3/min, p < 0.01; tidal volume, 439 +/- 128 ml and 541 +/- 165 ml, NS., before and after surgery, respectively). Sighing was absent before and after EAS and strictly reduced after elective surgery (p < 0.01 for UAS). The operation restricted the abdominal-diaphragmatic breathing movement which was reflected as increased contribution of the rib cage to VT (%RC: from 37% +/- 15 to 57% +/- 15 for UAS p < 0.001; from 47% +/- 16 to 61% +/- 14 for EAS NS.). After EAS and UAS hypoxemia was common (p < 0.001) with frequent radiological pathology. We conclude that intra-abdominal surgical emergencies increase the ventilatory demand and challenge the respiratory system to marked adaptive changes both pre- and post-operatively.

Hemodynamic effects of carotid endarterectomy by magnetic resonance flow quantification

BACKGROUND AND PURPOSE

Blood flow can be evaluated non-invasively using magnetic resonance phase-contrast flow quantification. The purpose of this prospective study was to assess the feasibility of this method and to evaluate the hemodynamic effects of carotid endarterectomy.

METHODS

Volumetric flow rates and peak systolic velocities of the internal and common carotid and the vertebral arteries were measured by magnetic resonance flow quantification. Sixteen patients undergoing 18 endarterectomies had complete flow data recorded preoperatively and 3 days after surgery.

RESULTS

The inverse correlation between the angiographic stenosis degree and the preoperative flow rate in the corresponding internal carotid artery was highly significant (r = -.69, P < .001). After endarterectomy, the mean flow in the ipsilateral internal carotid artery improved from 143 to 233 mL/min (P < .001). The mean peak systolic velocity increased from 23 to 37 cm/s (P < .001). No significant changes were seen in the contralateral carotid or the vertebral arteries. The mean total blood flow improved by 81 mL/min (P = .08). In the severely stenosed bifurcations (70% to 99%, n = 11), the flow rate improved by 106 mL/min and in the moderately (30% to 69%, n = 4) or mildly (< 30%, n = 3) stenosed bifurcations by 63 mL/min. If the contralateral carotid artery was occluded or severely stenosed, the improvement was 164 mL/min.

CONCLUSIONS

Magnetic resonance flow quantification provides a useful tool for the follow-up of the hemodynamic effects of carotid endarterectomy. Our results indicate that surgery is followed by a significant increase of blood flow in the ipsilateral carotid artery and that there appear to be differences in flow increase between subgroups of patients with different degrees of stenosis.

Carotid stenosis by digital subtraction angiography: reproducibility of the European Carotid Surgery Trial and the North American Symptomatic Carotid Endarterectomy Trial measurement methods and visual interpretation

PURPOSE

To evaluate different carotid stenosis estimation methods with digital subtraction angiography.

METHODS

We assessed the intraobserver reproducibilty and interobserver variability of visual interpretation and the measurement methods used by the European Carotid Surgery Trial and the North American Symptomatic Carotid Endarterectomy Trial. Angiographic stenosis measurements according to both criteria were performed twice by a radiologist, a neurologist, and a vascular surgeon. Eighty bifurcations of consecutive symptomatic patients underwent 480 pairs of measurements. In addition, four radiologists estimated the stenoses visually.

RESULTS

Intraobserver consistency was slightly better by the European (kappa, 0.86 to 0.94) than by the North American (kappa, 0.68 to 0.91) trial criteria or by visual interpretation (kappa, 0.79 to 0.81). No significant interobserver variability was found, except in the subgroup of mild stenoses by the North American Trial criteria. By kappa statistic, the interobserver agreement was excellent by the European trial method (kappa, 0.72 to 0.86), good by the North American trial method (kappa, 0.59 to 0.77), and good to excellent by visual evaluation (kappa, 0.68 to 0.88). The visual estimation agreed more closely with the European (kappa, 0.73 to 0.92) than with the North American trial (kappa, 0.55 to 0.74) criteria measurements.

CONCLUSIONS

All three methods have good reproducibility in digital subtraction angiography. Interobserver differences become more important in the estimation of mild stenosis.

Accuracy of digital videodensitometry in quantitating contrast medium concentration

To evaluate the accuracy of digital videodensitometric technique in directly quantitating concentration of contrast medium, iohexol 300 mg I/ml was injected into a 2-mm-diameter plastic tube, in which clean water was circulated at a 190 ml/min flow, for digital subtraction angiography. Altogether 27 injections were performed with 3, 4 and 5 ml volumes at 3-, 4- and 5-ml/s flows of the contrast medium. A time-density curve was achieved by selecting a "vessel" region of interest (ROI) and a background ROI. Then, a frame corresponding to the maximum opacification of the contrast medium could be calculated. Finally, the average density and the time to peak density of the contrast medium were obtained. The average density was statistically higher (p < 0.01) with 5 ml/s flow than with 4- and 3-ml/s flows. Times to peak density reduced as injection flows or volumes increased. The results support the conclusion that digital videodensitometric technique is an accurate method for quantitation of contrast medium concentration during angiography. The angiographic opacification may be improved by injecting the iodine contrast medium with higher flows or larger volumes.

Influence of carbon dioxide gas perfusion to thermal distribution of sapphire probe. A comparative study with saline

RATIONALE AND OBJECTIVES

A previous study confirmed that the direct laser-thermal conduction of the sapphire probe with carbon dioxide gas perfusion increased the width of the laser-recanalized channel. This caused us to further investigate the thermal distribution characteristics of the sapphire probe when lasing with CO2 gas perfusion.

METHODS

The surface temperature of a sapphire probe in a circulation model using 37 degrees C flowing whole blood was measured. Two hundred and sixteen measurements were obtained by directly contacting a flexible thermocouple wire onto the sapphire probe at different sites: 1) metal connector; 2) lateral side of the sapphire crystal; 3) top of the sapphire crystal; and 4) 3 mm in front of the sapphire probe. During lasing with a neodymium-yttrium-aluminum garnet (Nd-YAG) laser, the CO2 gas or saline was infused through the sapphire probe at different flow rates.

RESULTS

The lateral side of the sapphire crystal was heated up to 75 degrees C when lasing without any perfusion, but up to 220 degrees C when lasing with CO2 gas perfusion. At all four sites, the mean temperature increases were statistically higher (P < .01) with CO2 gas than with saline perfusion. The mean peak temperatures increased with increasing flows of CO2 gas perfusion and decreased with increasing flows of saline perfusion.

CONCLUSIONS

The thermal conduction from the sapphire probe can be significantly enhanced by increasing flows of CO2 gas perfusion. This may play an important role in creating a greater diameter of the recanalized channel and in better delaying the formation of restenosis or re-occlusion after laser recanalization of atheromatous arteries.

Predictors of conduction disturbances after coronary bypass grafting

One hundred sixty-nine patients undergoing coronary artery bypass grafting were included in a prospective study to test the effect of coronary pathology on conduction disturbances (CD). At the same time, several other proposed preoperative and intraoperative predictors of CD were collected. From the angiograms, the vascularization of the interventricular septum was classified according to Mosseri and colleagues. Ninety-four patients (56%) had type II coronary pathology, which does not allow full revascularization of the interventricular septum. The tested classification did correlate with the state of coronary disease, resulting in more left main coronary stenoses and more numerous peripheral anastomoses in type II patients. However, there was no correlation between the classification and CD. Patients with permanent CD (34%) had more left main coronary artery stenoses (29% versus 14%; p = 0.03). Their measured maximal myocardial temperatures were lower in all three myocardial regions measured (p = 0.01 to 0.07), and their creatine kinase MB fraction values on the day of operation were also higher (92 versus 70 IU; p = 0.002). In multivariate logistic regression analysis, the maximal temperature of the left circumflex artery region and the presence of left main coronary artery stenoses were the only independent predictors of permanent CD. We conclude that excessively low myocardial temperatures during cardioplegia may cause CD.

Sidebending versus flexion-extension radiographs in lumbar spinal instability

Flexion-extension radiography is accepted as an effective method for the diagnosis of lumbar spinal instability, but the usefulness of sidebending films is less well known. Flexion-extension and sidebending radiographs of 300 patients with clinically suspected lumbar spinal instability were analyzed retrospectively. Generally used criteria for lumbar spine instability were applied in the film analysis. Although flexion-extension and sidebending films were statistically significantly interrelated in the diagnosis of instability, intertechnique agreement remained poor. Flexion-extension films more frequently revealed signs of instability than sidebending films; 84 vs 50 patients. Signs of instability on sidebending films showed the best correlation with the findings of angular motion and posterior sliding instability on flexion-extension films. Sidebending films are complementary to flexion-extension films but are unlikely to be helpful on a routine basis.

Comparison of angiographic opacification of ioxaglate and iodixanol by digital region-of-interest processing technique in an experimental circulation model

RATIONALE AND OBJECTIVES

By using digital ROI (region of interest) processing techniques, we measured and compared directly the angiographic opacification of ioxaglate and iodixanol in an experimental circulation model.

METHODS

A pulsatile pump circulated water into a 2-mm plastic tube for digital subtraction angiography (DSA). Altogether, 90 digital imaging series were registered during injections of two contrast media with 320, 300, and 270 mg/mL iodine concentrations. By selecting a "vessel" ROI and a subtracted background ROI, a time-density curve (TDC) was created. From the TDC, the average density of contrast media and the appearance time of contrast media into the selected ROI were measured.

RESULTS

The average density was statistically different (P < .01) among three various iodine concentrations of the contrast media, but no difference was found between the two contrast media. The appearance times of ioxaglate with 320 mg/mL iodine concentration were statistically shorter (P < .01) than those of iodixanol. In both contrast medium groups, the appearance times were statistically shorter (P < .05) with 270 mg/mL iodine concentration than with two higher iodine concentrations.

CONCLUSION

The current experimental set-up facilitates reproducible measurement of angiographic opacification during the injection of contrast media. The average densities between ioxaglate and iodixanol are the same, but are significantly different among three iodine concentrations. The different appearance times of the two CM and the three iodine concentrations may be caused by the various viscosities of the contrast media.

Exercise therapy effects on functional radiographic findings and segmental electromyographic activity in lumbar spine instability

Flexion-extension and traction-compression radiographs as well as functional electromyographic (EMG) analysis were used to assess nine patients with chronic low back pain and segmental instability symptoms. After a treatment program, at which time most of the patients were asymptomatic and their physical status normalized, the patients were reexamined using EMG and radiographs. No significant change was found in the functional radiographic examination, whereas the myographic findings were significantly improved. Although the number of subjects was small, the results suggest that radiographic findings correlate poorly with clinical findings. Because of the improvement of the physical and myographic findings, the term "segmental dysfunction" may better describe the disability and symptoms than does the term "segmental instability."

Asymptomatic deep venous thrombosis in the calf: accuracy and limitations of ultrasonography as a screening test after total knee arthroplasty

Patients who have recently undergone total knee arthroplasty are at high risk of developing deep venous thrombosis (DVT) in the calf. The clinical diagnosis of DVT is difficult in these patients owing to recent operation. A combination of compression ultrasonography (US) and colour flow imaging was used as a screening method of asymptomatic DVT in 51 patients who had undergone total knee replacement surgery. Both limbs were examined by US from the common femoral vein to the ankle approximately 7 days after operation and the results were compared with bilateral venography. 12 patients (24%) developed infrapopliteal DVT on the operated side, in two cases the thrombosis extended to the lower part of popliteal vein. One patient had bilateral thrombosis. US showed sensitivity of 77%, specificity of 96% and overall accuracy of 93%. US seems to be a useful screening method for DVT after knee replacement operation.