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Embolic material generated by multiple aortic crossclamping: a perfusion model with human cadaveric aorta
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
2003 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, Vol. 125, no 6, 1451-1460 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Atherosclerosis of the ascending aorta and use of aortic crossclamping are risk factors for neurologic injury during cardiac surgery. OBJECTIVES: Repeated aortic manipulation is part of the surgical approach to most cardiac operations. The aim of this study was to assess the amount and size of particulate matter that is dislodged from the aortic wall as a function of repeated aortic crossclamping. METHODS: In 10 subjects undergoing autopsy the aorta was dissected and mounted in a perfusion model. The ascending aorta was crossclamped and washed out 10 times, with the perfusate collected in aliquots (1 to 10). The aliquots were examined by computerized image processing, both macroscopically and under the microscope for calcified and cellular material. RESULTS: Aortic crossclamping produced substantial output of particulate matter. After repeated aortic crossclamping the number of particles decreased (P =.012) and approached the baseline for aliquots 6 to 10. The average particle diameter was 0.63 +/- 0.03 mm, with a maximum of 4.74 mm. Similar variability in particle outputs were recorded microscopically, with findings of both calcified and cellular material. Nine of 10 aortas had calcifications seen during simple visual inspection. CONCLUSIONS: The washouts of dislodge material at aortic crossclamping had embolic potential. During the initial aortic crossclamping procedures the amount of particles was substantial, both macroscopically and microscopically. On the microscopic scale noncalcified cellular debris represents a significant pool of embolic material. Repeated aortic crossclamping reduced the amount of particles. These findings question surgical techniques associated with repeated aortic crossclamping.

Place, publisher, year, edition, pages
2003. Vol. 125, no 6, 1451-1460 p.
URN: urn:nbn:se:umu:diva-4806DOI: 10.1016/S0022-5223(03)00027-8PubMedID: 12830067OAI: diva2:144049
Available from: 2005-11-16 Created: 2005-11-16 Last updated: 2011-01-25Bibliographically approved
In thesis
1. Cerebrovascular accidents associated with aortic manipulation during cardiac surgery
Open this publication in new window or tab >>Cerebrovascular accidents associated with aortic manipulation during cardiac surgery
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Despite the successful development in cardiac surgery, cerebrovascular accidents (CVA) remain a devastating complication. Aortic atherosclerosis has been identified as a major risk factor for CVA. The present thesis addresses this question in relation to aortic manipulation during cardiac surgery, being divided into a clinical (I-II) and an experimental part (III-V).

Material and methods: Consecutive cardiac surgery cases (n=2641) were analyzed. Patients with CVA were extracted from a database designed to monitor clinical symptoms. Patient records were used to confirm clinical data and diagnosis. Subdivision was made into three groups: control subjects, immediate, and delayed CVA, being analyzed for neurological symptoms (I). Patients with CVA who also had been investigated with computer tomography (CT) (n=77) were further evaluated in terms of hemispheric and vascular distribution of lesions. The CT-findings were compared with CVA symptoms (II). An aortic perfusion model was developed using cadaver aorta onto which multiple cross-clamp manipulations were applied (III). Washout samples of perfusate were analyzed by computerized image processing and with subdivision into different particle spectra. The model was further developed with the introduction of intraluminal manipulation from cannula and intra-aortic filter (IV). A technique for macro-anatomic mapping of plaque distribution of cadaver thoracic aorta was developed (V). Variation in plaque density was analyzed in different anatomical segments, monitored by digital image analysis. Hazards associated with surgical manipulation were studied by superimposing cannulation and cross-clamp sites onto the aortic maps in a blinded fashion.

Results: The incidence of immediate and delayed CVA was 3.0% and 0.9%, respectively. Aortic quality was a strongly associated with immediate but not delayed CVA. Left-sided symptoms of immediate CVA were significantly more frequent than of the contra-lateral side. Positive signs on CT were seen in 66% of the CVA patients. Right-hemispheric lesions were more frequent compared with the contra-lateral side and the middle-cerebral artery territory dominated. Aortic cross-clamping produced a substantial output of particulate matter. Manipulation by intra-aortic filter produced a significant washout of embolic particles that escaped the filter, although some particles were captured. Cannulation was an additional source of embolic material. In terms of plaque distribution was the anterior wall of the ascending part and arch of the aorta more affected than its posterior side. However, observing a plaque in the anterior wall of this aortic segment predicted to 83% a concomitant plaque in the posterior wall. Increased age correlated positively with plaque density. The theoretical chance of interfering with a plaque during cannulation and/or clamp positioning was 45.8%.

Conclusions: Both CT scans and clinical symptoms confirmed that CVA after cardiac surgery had a right-hemispheric predominance. The perfusion model resulted in a profound output of material during cross-clamp maneuvers. The intra-aortic filter successfully collected particles but also generated embolic debris on its own. Aortic cannulation was an additional source of embolic debris. Plaques were frequently found in the cadaveric aorta, and there was a high risk of plaque interference during surgical manipulation. As expected, plaque density was age-dependent.

Place, publisher, year, edition, pages
Umeå: Kirurgisk och perioperativ vetenskap, 2005. 42 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 0346-6612
Surgery, aortic atherosclerosis, aortic cannulation, aortic cross-clamp, cardiac surgery, cerebral protection, cerebrovascular accidents, epiaortic ultrasound, intra-aortic filter, Kirurgi
National Category
Research subject
Thoracic and Cardivascular Suregery
urn:nbn:se:umu:diva-628 (URN)91-7305-954-4 (ISBN)
Public defence
2005-12-02, Sal B, Tandläkarhögskolan, 9 tr, Norrlands universitetssjukhus, 901 85 Umeå, 13:00 (English)
Available from: 2005-11-16 Created: 2005-11-16 Last updated: 2009-11-09Bibliographically approved

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