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Biomedical subjects

B Sonesson

Publications and source records attributed to B Sonesson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Abdominal aortic aneurysm wall mechanics and their relation to risk of rupture.

PURPOSE: to see whether aneurysmal aortic wall mechanics can be used as a predictor of abdominal aortic aneurysm (AAA) rupture. METHOD: among 285 individuals, followed conservatively for AAA and monitored for aneurysm growth and wall mechanics on at least one occasion at our institution between January 1991 and January 1998, eleven subsequently ruptured. Wall mechanics were estimated as stiffness (beta). This was calculated from diameter and pulsatile diameter change, determined non-invasively by an ultrasonic echo-tracking system and blood pressure obtained by the auscultatory method. The results were compared with those of 121 individuals electively operated on for AAA. RESULTS: no difference in aortic stiffness was found between those that subsequently ruptured (beta=35, median) compared to those non-ruptured (beta=38, median) AAAs (p=0.855). There was no difference in diameter in ruptured (58.8 mm) compared with non-ruptured (54.1 mm) AAAs (p=0.129). All ruptured AAAs showed an expansion of diameter over time. CONCLUSION: this study shows no difference in aneurysmal aortic wall mechanics in those AAAs that subsequently ruptured compared with electively operated AAAs. The results indicate that it is not possible to use aneurysmal aortic wall stiffness as a predictor of rupture.

Aged↗
PubMed1998

The fate of the infrarenal aortic neck after open aneurysm surgery.

PURPOSE: The long-term success of the endovascular repair of abdominal aortic aneurysms is dependent on the secure fixation of the stent graft at the proximal and distal attachment sites. A progressive dilatation of the infrarenal neck may jeopardize this success. The data regarding this issue are scarce. However, the long-term fate of the infrarenal neck can be studied in patients who have undergone open aneurysm surgery. This was the purpose of the present investigation. METHODS: Between January 1989 and December 1993, 64 patients underwent open repair of infrarenal abdominal aortic aneurysms. Of the 36 patients who were eligible for the study, 19 had preoperative computed tomography scans that were available. The 19 patients also underwent a new computed tomography scanning at a mean of 71 +/- 12 months after surgery. RESULTS: The mean preoperative aortic diameter was 25.4 +/- 3.7 mm at the infrarenal neck, 24.8 +/- 3.4 mm at the level of the renal arteries, and 26.7 +/- 3.0 mm at the level of the superior mesenteric artery (SMA). The mean aortic diameter increased at all of the 3 levels: +2.8 +/- 3.1 mm (P =.0014) at the infrarenal neck, +2.8 +/- 3.0 mm (P =.0013) at the level of the renal arteries, and +1.3 +/- 3.0 mm (P = .080) at the level of the SMA. The annual growth rate was 0.48 mm/y (P = .0023) at the infrarenal neck, 0.46 mm/y (P =.0010) at the level of the renal arteries, and 0.21 mm/y (P = .5811) at the level of the SMA. No correlation was found between the preoperative infrarenal neck diameter (r = .295, P = .2194), the preoperative aortic diameter at the level of the renal arteries (r = .302, P = .2088), and the preoperative aortic diameter at the level of the SMA (r = .314, P =. 2043) and the corresponding growth rates. The patients were stratified into 2 groups one with a small annual growth rate at the infrarenal neck (n = 11; </= 0.3 mm/y) and one with a larger annual growth rate (n = 8; > 0.3 mm/y) and no differences in the preoperative infrarenal neck diameter or the clinical characteristics were found between the groups. CONCLUSION: This investigation shows an aortic dilatation of the infrarenal neck and of the aorta at the level of the renal arteries of approximately 0.5 mm annually after open aneurysm surgery. This dilatation raises concern regarding the long-term success after endovascular repair. The data also indicate that 2 populations might exist with regard to the annual growth rate of the infrarenal neck one with low growth rate and one with higher growth rate. This might be of interest for the future selection of patients for endovascular repair.

Aged↗
PubMed1998

Factors predicting the diameter of the popliteal artery in healthy humans.

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.

Adolescent↗
PubMed1998

A dynamic view on the diameter 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 m2 (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 dilatation 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.

Aged↗
PubMed1998

Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm.

PURPOSE: To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs). METHODS: Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA). RESULTS: The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck. CONCLUSIONS: This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.

Aged↗
PubMed1997

Stiffness and diameter of the common carotid artery and abdominal aorta in women.

Vascular disease is differentiated throughout the vascular regions with aorta more prone to dilatation and with peripheral arteries more prone to occlusive disease. In this study, we investigated the diameter and distensibility in the common carotid artery (CCA) and abdominal aorta (AO) in healthy females of varying ages to assess potential differences in the aging process. The diameter and pulsatile diameter change of the CCA and AO in 66 healthy Caucasian females aged 8 to 79 y were examined using an ultrasound phase-locked echo-tracking technique. Blood pressure was obtained by the auscultatory method. Arterial stiffness (beta) was calculated. The diameter of both CCA and AO increases, not only in childhood, but also in adult women. The dilatation in adults (25 to 75 y) seems to be more pronounced in the AO (23%) than in the CCA (11%). Stiffness (beta) is higher in the CCA than AO before 20 y of age (p < 0.05). Stiffness increases with aging in both arterial regions, but the increase is initially somewhat higher in the AO, which means that no differences between the CCA and AO are seen from 25 y onward. In conclusion, this study demonstrates regional differences in diameter change and stiffness in the CCA and AO, and implies that the AO is more prone to age-related changes of the arterial wall than the CCA. These differences, however, are not as marked as previously reported in males.

Adolescent↗
PubMed1997

Abdominal aortic aneurysm: a general defect in the vasculature with focal manifestations in the abdominal aorta?

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 (beta) was studied in 121 individuals (101 men, 20 women) who were admitted for elective repair of AAA. Stiffness (beta) 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.

Aged↗
PubMed1997

Improved reliability of ultrasonic surveillance of abdominal aortic aneurysms.

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.

Adult↗
PubMed1997

Changes in aortic wall stiffness in men with alpha 1-antitrypsin deficiency.

OBJECTIVES: To examine the diameter and distensibility of the abdominal aorta in patients with severe alpha 1-antitrypsin deficiency, and to compare the results with those of normal subjects. MATERIAL AND METHODS: Abdominal aortic diameter and stiffness (beta) 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 alpha 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 alpha 1-antitrypsin deficiency when corrected for age, sex and body surface area (men p = 0.20, women p = 0.10). Men with alpha 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 alpha 1-antitrypsin deficiency compared with controls. However, aortic distensibility in men with alpha 1-antitrypsin deficiency is altered. This may reflect early vessel wall abnormality.

Adult↗
PubMed1997

The mechanical properties of elastic arteries in Ehlers-Danlos syndrome.

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 Ep (pressure strain elastic modulus) and stiffness (beta) in twelve individuals with EDS of different subtypes and compared with the results of a healthy reference population. Ep and beta 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, Ep and beta 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), Ep (males p = 0.81, females p = 0.27) and beta (males p = 0.95, females p = 0.12). CCA: diameter (males p = 0.36, females p = 0.46), Ep (males p = 0.93, females p = 0.48) and beta (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 physiological pressure conditions.

Adolescent↗
PubMed1997

Influence of sympathetic stimulation on the mechanical properties of the aorta in humans.

The mechanical properties of the aorta play a major role in the regulation of blood pressure and cardiac performance. The effect of sympathetic stimulation on the mechanical properties of the human abdominal aorta was studied in 19 healthy volunteers, divided into young (25 +/- 2 years) and elderly individuals (69 +/- 2 years) of both sexes. A non-invasive ultrasonic echo-tracking system for measurement of systolic/diastolic variation of aortic diameter in combination with intra-aortic pressure measurements was used to determine wall mechanics. The pressure-diameter (P-D) relationship and the distensibility indices, stiffness (beta) and pressure strain elastic modulus (Ep) of the abdominal aorta were obtained. Measurements were made at rest and during sympathetic stimulation induced by lower body negative pressure (LBNP). As a sign of sympathetic activation, the peripheral resistance increased by 74-96% (P < 0.001) during LBNP. However, the mechanical properties of the abdominal aorta remained unaltered, as estimated either from the P-D relationship or from the indices Ep and beta, both in the young (rest: Ep = 0.53 +/- 0.18, beta = 4.5 +/- 1.5; LBNP: Ep = 0.51 +/- 0.15, beta = 4.5 +/- 1.2, NS) and in the elderly (rest: Ep = 2.17 +/- 0.70, beta = 17.6 +/- 5.8; LBNP: Ep = 2.11 +/- 0.60, beta = 16.9 +/- 3.9, NS). In conclusion, this investigation shows that LBNP-induced sympathetic activation does not change aortic wall mechanics. Thus, sympathetic modulation of the aortic smooth muscle contractile activity seems to be unimportant in the blood pressure regulation.

Adult↗
PubMed1997

Does long-term smoking affect aortic stiffness more in women than in men?

Smoking is a well-known risk factor for cardiovascular disease, although understanding of the pathophysiological mechanism is incomplete. The effect of heavy smoking, for more than 20 years and of 20 cigarettes per day, on aortic stiffness was studied in women (n = 23, age range 43-61 years) and men (n = 21, age range 43-61 years) who smoked but were otherwise healthy and compared with a healthy reference population that did not smoke. Aortic stiffness (beta) was calculated from the diameter and the pulsatile diameter change determined non-invasively using an ultrasonic echo-tracking system and blood pressure obtained by the auscultatory method. The results showed that aortic diameter did not differ in smoking males (P = 0.974) or in smoking females (P = 0.361). Aortic stiffness was increased in the female (P = 0.041) but not male smokers (P = 0.222). Systolic, mean and diastolic blood pressure in the men and women who smoked did not differ from those in the healthy reference population. In conclusion, this investigation shows increased aortic stiffness in female but not in male smokers. It indicates that the aorta of women might be more vulnerable to smoking with regard to stiffening and degeneration than the aorta of men.

Adult↗
PubMed1996

SPECT with technetium-99m-HMPAO in relation to late cognitive outcome after surgery for ruptured cerebral aneurysms.

Fifteen patients with a good neurological outcome after aneurysmal SAH and surgery were collected prospectively. Six months after surgery neurological examination and a SPECT study for evaluation of the three dimensional CBF distribution as well as an extensive neuropsychological test were performed. In all patients with pathological SPECT findings the location of the reduced regional CBF correlated with the location of the ruptured aneurysm and/or side of surgical approach. The volume of the brain tissue with reduced rCBF showed a great variety, from 9-112 cm(3) (mean: 33 cm(3)). Similarly, the maximum flow reduction in the affected areas also varied considerably from 17-95% (mean: 39%). In general, the neuropsychological functioning of the patients post SAH was favourable. Seven individuals had a presumably normal neuropsychological appearance with respect to estimates of premorbid levels of functioning. Another four patients were slightly impaired and the remaining four were moderately affected. Only in five cases did the location of SPECT pathology and the site of neuropsychological impairment appear to coincide, whereas this was not the case in the remaining 10 patients. In general, the extent of SPECT pathology did not differ in the three neuropsychological outcome groups (normal, slight and moderate disability).

Adult↗
PubMed1996

Regional differences in mechanical properties between major arteries--an experimental study in sheep.

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 (beta) calculated. Distensibility was defined as the inverse of Ep and stiffness. RESULTS: The AA showed lower values for Ep and stiffness (beta) 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.

Animals↗
PubMed1995

Increased arterial stiffness in women, but not in men, with IDDM.

For unknown reasons, there is a greater increase in the risk for cardiovascular complications in diabetic women than in diabetic men. Our aim was to study gender-related differences in the mechanical properties of the great arteries in patients with insulin-dependent diabetes mellitus (IDDM) but free from known cardiovascular and cerebrovascular complications. We measured arterial stiffness (beta, inversely related to arterial compliance) in the abdominal aorta and the common carotid artery non-invasively using echo-tracking sonography in 30 women (mean age 34 years, range 20-61) and 26 men (mean age 38 years, range 22-56) with IDDM. The results were compared with those of healthy individuals of corresponding age and gender. The results showed a marked gender-difference in changes of arterial stiffness. Arterial stiffness was increased in both the abdominal aorta and the common carotid artery in diabetic women compared to control women (p = 0.0001 and p = 0.0076, respectively). In contrast, there was no significant difference in stiffness of the abdominal aorta or the common carotid artery between the diabetic men and the control men (p = 0.69 and p = 0.39, respectively). In conclusion, this study has shown that stiffness of the aorta and the common carotid artery is increased in diabetic women but not in diabetic men. Increased arterial stiffness in diabetic women may be a pathogenic factor which could help to explain the gender-related differences in the risk for cardiovascular and cerebrovascular complications in diabetic subjects.

Adult↗
PubMed1995

Diameter and compliance in the human common carotid artery--variations with age and sex.

In this study, age and sex differences in diameter and compliance of the common carotid artery (CCA) were evaluated in 119 healthy subjects with a phase-locked echo-tracking system. The diameter and pulsatile diameter changes were measured, and pressure strain elastic modulus (Ep) and stiffness (beta) were calculated and used as the inverse estimate of compliance. The carotid diameter increased more rapidly in males and was larger than in females from 25 years of age. The relative diameter change was equal in both sexes, and decreased from 12% to 14% in younger subjects to approximately 5% in elderly subjects. Compliance decreased almost linearly and in parallel in males and females up to 45 years of age. Between 45 and 60 years the decrease was more marked in females than in males, whereas it was by far more marked in males between 60 and 70 years of age.

Adolescent↗