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Purpose: To determine the relevance of popliteal dilatations, knowledge of the normal popliteal artery diameter is essential. This study investigates the diameter of the popliteal artery in healthy males and females. Methods: We measured the diameter of the popliteal artery in 121 healthy volunteers (59 males and 62 females), ages 8 to 81, with echo-tracking B-mode ultrasonography. We analyzed the influence of age, sex, height, weight, body surface area (BSA) and systolic blood pressure with a multiple regression model. Results: The popliteal artery increased steadily in diameter throughout life. From 25 years on, the diameter was larger in males than in females. If corrected for BSA, this difference decreased from 17% to 7%. This study found a correlation between popliteal artery diameter and BSA (r = 0.47 and r = 0.61, respectively, p < 0.0001). Age, followed by BSA, was the most influencing factor on popliteal diameter in both males and females (r = 0.62 and r = 0.66, respectively, p < 0.0001). We used age and BSA in creating a model for prediction of popliteal artery diameter. Conclusions: The diameter of the popliteal artery increases with age, initially during growth, but also in adults. This is related to age, body size and sex, with males having larger arteries than females. It is now possible to predict the normal popliteal arterial diameter, and nomograms are presented for use in the study of aneurysmal arterial disease. (J Vasc Surg 1998;28:284-9.)

Purpose: The reduced size of abdominal aortic aneurysms (AAAs) after endovascular repair suggests lowered intraaneurysmal pressure. In the presence of endoleaks, the size is not decreased. Although postoperative intraaneurysmal pressure is difficult to record, the pulsatile wall motion (PWM) of aneurysms can be measured noninvasively. The aim of this study was to assess the PWM of AAAs before and after endovascular repair and to relate the change in the PWM to aneurysmal size and presence of endoleaks. Methods: Forty-seven patients underwent endovascular repair of an AAA. The aneurysm diameter and PWM were measured with the use of ultrasonic echo-tracking scans preoperatively; at 1, 3, and 6 months; and thereafter biannually. Fifteen aneurysms developed endoleaks, whereas 32 were completely excluded. The leaks were characterized with the use of computed tomographic scanning and angiography. Median follow-up was 12 months (interquartile range, 5 to 24 months). Results: The preoperative PWM of the aneurysms was 1.0 mm (range, 0.8 to 1.3 mm). After complete endovascular exclusion, the PWM was 25% (range, 16% to 37%) of the preoperative value (p < 0.001), and aneurysm diameter decreased by 8 mm (range, 6 to 14 mm) (p < 0.001). After 18 months, no further diameter reduction occurred. In three patients without endoleaks but with enlarging aneurysms, the postoperative PWM showed less reduction (p < 0.05). Aneurysms with endoleaks showed no diameter decrease, and the postoperative PWM was 50% higher than that in the totally excluded cases (p < 0.01). In five patients with transient endoleaks, the PWM was reduced after leakage ceased (p < 0.05). Leaks of various sources displayed similar PWM. Conclusion: The size and PWM of aneurysms are reduced after endovascular repair. The diameter reduction may cease after 1.5 years. Endoleaks are associated with higher PWM than expected. Pressure may be transmitted without evidence of leaks. (J Vasc Surg 1998;27:624-31.)

Purpose: It has been suggested that abdominal aortic aneurysms (AAA) develop as a result of an alteration in the systemic connective tissue metabolism. This might change wall mechanics and diameter, not only in the AAA but also in the rest of the vascular system. This hypothesis was tested by studying the mechanical properties of AAAs as well as the common carotid artery (CCA) in the same patient population. Methods: AAA and carotid artery stiffness (@b) was studied in 121 individuals (101 men, 20 women) who were admitted for elective repair of AAA. Stiffness (@b) was calculated from diameter and pulsatile diameter change determined noninvasively from an ultrasonic echo-tracking system and blood pressure obtained by the auscultatory method. The results were compared with those of healthy individuals of corresponding age and gender published elsewhere. Results: The stiffness of the AAA was increased in both men and women (p = 0.0001). The increase was more pronounced in women compared with men (p = 0.0003) to a mean of 435% and 189% of the normal predicted values, respectively. In the CCA, the stiffness was increased in men (p = 0.027) and in women (p = 0.0001) to a mean of 131% and 149% of the normal predicted values, respectively. A significant correlation between stiffness in the aneurysm and in the carotid artery was seen (p = 0.0031). The carotid diameter was unchanged in men (p = 0.924) and in women (p = 0.070) if adjusted for the difference in blood pressure between the individuals with AAAs and control subjects. There was no correlation between stiffness and diameter of the aneurysm in men (r = 0.16, p = 0.119) nor in women (r = 0.12, p = 0.598). Conclusions: This investigation demonstrated altered mechanical properties of the aneurysmal wall as well as in the CCA in individuals with AAAs. The normal age- and gender-related differences seen in the healthy aorta and CCA vanished. The results suggest that AAA is a generalized process of the vasculature with focal manifestation in the abdominal aorta. (J Vasc Surg 1997 26:247-54.)

Aim:: To investigate a series of patients with secondary aortoenteric fistulas and compare it with a previous series (1985-93 vs. 1973-84). Design:: Retrospective study of medical records. Setting:: Sixteen vascular surgical centres in Sweden. Patients:: Twenty-seven patients were identified making an overall incidence of 0.5% of all aortoiliac operations. Among aneurysm patients the incidence was significantly lower than in the previous series. One patient record could not be identified. Fourteen primary operations were for aortic aneurysm, 12 for occlusive disease and one was an aortorenal vein bypass. Results:: Symptoms of the fistula occurred after a median interval of 90 months which is significantly later than the previous series (32 months; p < 0.05). The commonest presentation was bleeding followed by septis. The median diagnostic delay was 10.5 days, which was significantly shorter than in the previous series. Most fistulas involved the duodenum (88%). One patient died before surgery. The postoperative mortality was 28%, significantly lower than in the previous series (58%) (p < 0.05). At the end of follow up (median 43 months) significantly more patients were alive than in the previous series (42% vs. 18%) (p < 0.05). Conclusion:: Over a 21 year period there seems to have been a decrease in the frequency of secondary aortoenteric fistulas after aneurysm surgery, a longer interval before they occur, a shorter diagnostic delay, and a better survival.

Objectives:: The aim of this prospective study was to contribute to the evaluation of the reliability of Duplex sonography (DS) before carotid endarterectomy (CEA). Design:: The study was performed prospectively in a university hospital setting. Methods:: Eighty-one consecutive patients aged 49-83 years were examined with DS and carotid angiography (CAG) before CEA. The results of the DS were judged as either confident, or CAG was assessed to be necessary preoperatively. The results from the DS and the CAG were then compared. Results:: DS was judged as confident in 148 of the 162 arteries examined. In none of these 148 arteries did CAG change patient management in any way, and the agreement between DS and CAG was good. In the remaining 14 arteries CAG was judged necessary, in 11 arteries because DS assessed the internal carotid artery (ICA) as occluded, which was confirmed by CAG in 10 arteries. In three arteries the reason was poor quality of the DS, however these three arteries were correctly assessed as severely diseased. Conclusions:: This study confirms that DS alone is sufficient in the preoperative evaluation before CEA, provided that CAG is performed whenever DS shows occlusion of the ICA, or when the quality of the DS is poor.

Objective:: To study the stent/vessel interaction and distensibility following the natural increase in vascular diameter using self-expanding and balloon-expanded stents. Design:: Open experimental study. Setting:: Animal laboratory, university hospital. Materials and methods:: Eight Palmaz (P) and eight Gianturco (G) stents were transluminally placed in the infrarenal aortas of 16 pigs. Pulsatile diameter changes above, at and below the stents were non-invasively monitored with an ultrasound phase-locked echo-tracking system before and immediately after stenting and at 4 and 18 weeks. Blood pressure was registered intra-arterially and stiffness (@b) was calculated. Intravascular ultrasound (IVUS) was performed at 18 weeks. Results:: Median weight increased from 20 kg (19-26) to 93 kg (62-130). Diameter of the aorta increased 60%. In group P no pulsatile diameter change could be measured at the stent (@b = ~). In group G stenting increased stiffness from @b 20.7 (9.2) to 43.2 (8.0) (p < 0.05). After 18 weeks stiffness returned to @b 20.1 (12.4). Expanded, median diameter of the P stents was 7.4 (0.8) mm, not increasing after 18 weeks. Initial diameter of the G stents was 7.8 (1.0) mm, increasing 56% to 12.2 (2.3) mm (p < 0.05). IVUS revealed the G stents to be well attached to the vascular wall, but five P stents were detached within half of the circumference. Conclusion:: Self-expanding stents follow the pulsatile diameter change of the vessel wall, not adversely affecting distensibility after 18 weeks. They show good attachment despite 56% dilation. In contrast, the balloon-expanded stents do not show pulsatile movement and may detach during vessel diameter increase. This may be of importance when choosing stents for endovascular treatment of abdominal aortic aneurysms.

Objectives:: To study 40-55 mm aneurysms and calculate their size in relation to the individual predicted normal aortic diameter to see if this might add anything in the evaluation of treatment. Material and methods:: The anteroposterior diameter of 40-55 ,mm AAAs was measured with an echo-tracking ultrasonic technique in 147 consecutive patients. The weight and height were registered and body surface area calculated. The predicted normal aortic diameters were defined according to nomograms and the diameter increase from the predicted normal aortic size in the individual aneurysms calculated. Results:: The median AAA diameter was 48 mm (range 40-55), the BSA 1.85 m^2 (1.42-2.37), and the predicted AO size 19.4 mm (14.3-21.6). The calculated increase of size in the individual aneurysms was 2.51 (1.9-3.53), that is the spread of data doubled as compared to conventional diameter measurements. When females and males were studied separately the AAA diameter was 46.5 mm (40-55) and 48 mm (40-55), respectively (NS). Since the BSA was significantly lower in women than in men, 1.63 (1.42-1.95) and 1.89 (1.47-2.37), respectively (p<0.0001), also the predicted normal aortic size was lower, 16.4 (14.3-17.8) vs. 19.7 (18.0-21.6) (p<0.0001). Thus, the AAA diameter increase from the predicted size was larger in women than in men; 2.93 (2.25-3.53) vs. 2.46 (1.90-2.94), respectively (p<0.0001). Conclusion:: To define an aneurysm as a localised dialtation of an artery exceeding 50% of the expected normal diameter is now possible. This may facilitate how to treat especially smaller aneurysms and give new information concerning patterns of growth and risk of rupture.

Objectives:: To examine the diameter and distensibility of the abdominal aorta in patients with severe @a"1-antitrypsin deficiency, and to compare the results with those of normal subjects. Material and methods:: Abdominal aortic diameter and stiffness (@b) was measured using echo-tracking sonography in 19 men (mean age 50, range 25-79) and 17 women (mean age 46, range 26-62) with severe @a"2-antitrypsin deficiency. The results were compared with those of healthy individuals of corresponding age and gender. Results:: There was no significant difference in the abdominal aortic diameter between controls and patients with @a"1-antitrypsin deficiency when corrected for age, sex and body surface area (men p = 0.20, women p = 0.10). Men with @a"1-antitrypsin deficiency showed significantly lower stiffness in the abdominal aorta compared to controls (p = 0.025), whereas women did not (p = 0.17). Conclusions:: No significant difference in abdominal aortic diameter could be detected in patients with @a"1-antitrypsin deficiency compared with controls. However, aortic distensibility in men with @a"1-antitrypsin deficiency is altered. This may reflect early vessel wall abnormality.

Objective:: To study whether measurements of wall mechanics can be used as an indicator of disturbed vessel wall integrity and predictor of vessel fragility in Ehlers-Danlos Syndrome (EDS). Methods:: The wall mechanics of the abdominal aorta (AO) and common carotid artery (CCA) were estimated from the indices E"p (pressure strain elastic modulus) and stiffness (@b) in twelve individuals with EDS of different subtypes and compared with the results of a healthy reference population. E"p and @b were calculated from diameter and pulsatile diameter change determined non-invasively with the aid of an ultrasonic echo-tracking system and blood pressure obtained by the auscultatory method. Results:: Compared with normal individuals and their confidence intervals, subjects with EDS had unaltered diameter, E"p and @b in the AO, as well as in the CCA. Analysis of covariance (ANCOVA) also showed unaltered results. AO: diameter (males p = 0.66, females p = 0.27), E"p (males p = 0.81, females p = 0.27) and @b (males p = 0.95, females p = 0.12). CCA: diameter (males p = 0.36, females p = 0.46), E"p (males p = 0.93, females p = 0.48) and @b (males p = 0.86, females p = 0.47). Conclusions:: This investigation could not demonstrate any alteration in wall mechanics as a sign of disturbed vessel wall integrity of elastic arteries in EDS. This might indicate that the structural defect in the arterial wall collagen, and thus the tendency to vessel fragility, cannot be revealed under normal physilogical pressure conditions.

Objectives:: Small abdominal aortic aneurysms (AAA) are usually managed conservatively by serial ultrasound examinations to assess size. The development of the size of the AAA will determine whether the patient is a candidate for surgery. The precision of measurement is therefore of considerable importance. The aim of this study was to evaluate the accuracy and the reproducibility of a newly developed echo-tracking ultrasonic system in the size evaluation of AAA. Design:: Prospective study at a University Hospital. Material and methods:: An echo-tracking ultrasound system with a 3.5 MHz transducer was used in 54 patients with AAA. Thirty-six patients had repeated measurements by one technician to evaluate the intra-observer variability. In another 18 patients with aortic dilatation/AAA, the measurements were repeated by a second technician in a blinded fashion with calculation of inter-observer variability. The reproducibility was evaluated both using linear regression and plots according to the method described by Bland and Altman. Results:: The mean diameter of the aorta was 37 mm (range 21-51 mm). The coefficient of correlation of repetitive measurements with one observer was r = 0.99 and with two observers r = 0.99. The intra-observer variability was 0.78 mm (s.d.) and the inter-observer variability 0.93 mm (s.d.). The intra- and inter-observer coefficient of variation (CV) was 2-3%. Conclusions:: The newly developed echo-tracking ultrasonography seems at present to be the most accurate and reliable method to follow the diameter of an abdominal aortic aneurysm detecting relevant changes in the diameter exceeding 2 mm (2 s.d.). Thus it fulfils the requirements both for follow-up of conservatively managed AAAs and endovascularly treated aneurysms.

Purpose:: To study possible differences in mechanical properties between central (abdominal aorta) and more peripheral (common carotid and common femoral) arteries validating an earlier non-invasive study in children showing that central arteries are more distensible than peripheral ones. As invasive blood pressure was needed, but ethically impossible to obtain in children in an experimental setting, an animal model was chosen. Design:: Open experimental study. Setting:: Animal laboratory at university hospital. Material and methods:: The pulsatile vessel wall movements of the abdominal aorta (AA), common femoral (CFA) and common carotid (CCA) artery of nine sheep were examined using an ultrasound phase-locked echo-tracking technique. Intra-arterial blood pressure was measured and pressure-diameter relations, pressure strain elastic modulus (Ep) and stiffness (@b) calculated. Distensibility was defined as the inverse of Ep and stiffness. Results:: The AA showed lower values for Ep and stiffness (@b) than the CFA (p = 0.002) and CCA (p = 0.006), i.e. the latter two vessels were stiffer. The pressure-diameter relations confirmed these differences and showed a non-linearity for all three vessels with increased stiffness above 70-90 mm Hg. Conclusion:: This study on young animals supports earlier findings of differences in mechanical properties between central and more peripheral arteries seen in healthy children. As pathologies between these vessels differ, with dilatation of the abdominal aorta and occlusive disease in the more peripheral vessels, part of the explanation might be found in the mechanical properties of the healthy vessels, characterised here with the echo-tracking technique.