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Cerebrovascular accidents associated with aortic manipulation during cardiac surgery
Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences.
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.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 0346-6612
Keyword [en]
Surgery, aortic atherosclerosis, aortic cannulation, aortic cross-clamp, cardiac surgery, cerebral protection, cerebrovascular accidents, epiaortic ultrasound, intra-aortic filter
Keyword [sv]
Kirurgi
National Category
Surgery
Research subject
Thoracic and Cardivascular Suregery
Identifiers
URN: urn:nbn:se:umu:diva-628ISBN: 91-7305-954-4 (print)OAI: oai:DiVA.org:umu-628DiVA: diva2:144052
Public defence
2005-12-02, Sal B, Tandläkarhögskolan, 9 tr, Norrlands universitetssjukhus, 901 85 Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2005-11-16 Created: 2005-11-16 Last updated: 2009-11-09Bibliographically approved
List of papers
1. Side differences in cerebrovascular accidents after cardiac surgery: a statistical analysis of neurologic symptoms and possible implications for anatomic mechanisms of aortic particle embolization.
Open this publication in new window or tab >>Side differences in cerebrovascular accidents after cardiac surgery: a statistical analysis of neurologic symptoms and possible implications for anatomic mechanisms of aortic particle embolization.
2005 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, E-ISSN 1097-685X, Vol. 129, no 3, 591-598 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Aortic manipulation and particle embolization have been identified to cause cerebrovascular accidents in cardiac surgery. Recent data suggest that left-hemispheric cerebrovascular accident (right-sided symptoms) is more common, and this has been interpreted as being caused by aortic cannula stream jets. Our aim was to evaluate symptoms of cerebrovascular accident and side differences from a retrospective statistical analysis. METHODS: During a 2-year period, 2641 consecutive cardiac surgery cases were analyzed. Patients positive for cerebrovascular accident were extracted from a database designed to monitor clinical symptoms. A protocol was used to confirm symptom data with the correct diagnosis in patient records. Patients were subdivided into 3 groups: control, immediate cerebrovascular accident, and delayed cerebrovascular accident. RESULTS: Among pooled patients, immediate and delayed cerebrovascular accidents were 3.0% and 0.9%, respectively. The expected predisposing factors behind immediate cerebrovascular accidents were significant, although the type of operation affected this search. Aortic quality was a strong predictor ( P < .001). The rate of delayed cerebrovascular accident was unaffected by surgery group. Left-sided symptoms of immediate cerebrovascular accident were approximately twice as frequent ( P = .016) as on the contralateral side. This phenomenon was observed for pooled patients and for isolated coronary bypass procedures (n = 1882; P = .025). CONCLUSIONS: Immediate cerebrovascular accident and aortic calcifications are linked. The predominance of left-sided symptoms may suggest that aortic manipulation and anatomic mechanisms in the aortic arch are more likely to cause cerebrovascular accidents than effects from cannula stream jets.

Keyword
Aged, Aortic Diseases/*epidemiology, Arteriosclerosis/*epidemiology, Cardiopulmonary Bypass, Coronary Artery Bypass, Female, Humans, Male, Middle Aged, Retrospective Studies, Stroke/*epidemiology/physiopathology, Time Factors
Identifiers
urn:nbn:se:umu:diva-6035 (URN)10.1016/j.jtcvs.2004.07.020 (DOI)15746743 (PubMedID)
Available from: 2007-12-05 Created: 2007-12-05 Last updated: 2017-12-14Bibliographically approved
2. Cerebrovascular accidents after cardiac surgery: an analysis of CT scans in relation to clinical symptoms
Open this publication in new window or tab >>Cerebrovascular accidents after cardiac surgery: an analysis of CT scans in relation to clinical symptoms
2005 (English)In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 39, no 5, 299-305 p.Article in journal (Refereed) Published
Abstract [en]

There is a link between aortic manipulation, particle embolization, and cerebrovascular accidents (CVA) in cardiac surgery. The present aim was to study hemispheric side differences of CVA. Cardiac-surgery patients with CVA and with computer tomography (CT) performed (n = 77) were analyzed within a total group of 2641 consecutive cases. CT data were reviewed for hemispheric and vascular distribution, and compared with CVA-symptom data of immediate and delayed type. Of the included patients, 66% had positive CT. In the group of 'cardiac-type' operations (e.g., routine clamping and cannulation) and having immediate CVA, right-hemispheric lesions were more frequent than of the contra-lateral side (p = 0.005). Patients with aortic dissections had strong dominance of bilateral findings, which was different from the unilateral pattern of 'cardiac-type' operations (p = 0.001). The middle-cerebral artery territory dominated, and when involved showed a significant (p = 0.022) right-sided distribution. Both CT and clinical symptoms confirmed that CVA after cardiac surgery has a right-hemispheric predominance. These observations may imply that aortic manipulation directs embolic material towards the brachiocephalic trunk.

Keyword
Aged, Cardiac Surgical Procedures/*adverse effects, Coronary Artery Bypass, Dominance; Cerebral, Female, Humans, Intracranial Embolism/etiology, Male, Middle Aged, Postoperative Complications/radiography, Risk Factors, Stroke/etiology/*radiography, Telencephalon/radiography, Tomography; X-Ray Computed
Identifiers
urn:nbn:se:umu:diva-6034 (URN)10.1080/14017430510035907 (DOI)16269400 (PubMedID)
Available from: 2007-12-05 Created: 2007-12-05 Last updated: 2017-12-14Bibliographically approved
3. Embolic material generated by multiple aortic crossclamping: a perfusion model with human cadaveric aorta
Open this publication in new window or tab >>Embolic material generated by multiple aortic crossclamping: a perfusion model with human cadaveric aorta
2003 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, E-ISSN 1097-685X, 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.

Identifiers
urn:nbn:se:umu:diva-4806 (URN)10.1016/S0022-5223(03)00027-8 (DOI)12830067 (PubMedID)
Available from: 2005-11-16 Created: 2005-11-16 Last updated: 2017-12-14Bibliographically approved
4. Intraluminal aortic manipulation by means of intra-aortic filter, cannulation, and external clamp maneuvers evaluated versus dislodged embolic material.
Open this publication in new window or tab >>Intraluminal aortic manipulation by means of intra-aortic filter, cannulation, and external clamp maneuvers evaluated versus dislodged embolic material.
2006 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, E-ISSN 1097-685X, Vol. 131, no 2, 283-289 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Aortic atherosclerosis is an important risk factor for cerebrovascular accidents in cardiac surgery. An intra-aortic filter might reduce this risk. We aimed to analyze the risks for emboli associated with intraluminal aortic manipulation and intra-aortic filter handling in relation to cannulation and external clamp maneuvers. METHODS: A model was designed with a cadaver aorta and retrograde perfusion (n = 16). A crossclamp was positioned on the ascending aorta and repeatedly opened under pressure to collect aliquots with dislodged particles. Cannulation was performed after 10 clamp maneuvers, followed by positioning and removing the intra-aortic filter, with each step followed by a washout sequence to collect perfusate. The removed filter was also analyzed. Evaluation was by means of digital image analysis, with differentiation of particles into different spectra. RESULTS: Intra-aortic filter manipulation produced a significant washout of embolic particles; in particular, this was seen for the macroscopic cellular spectrum (P = .006 and P = .002 for filter insertion and removal, respectively). Particles were also found to be collected by the filter (P = .004). In addition, cannulation and aortic crossclamp manipulation generated a notable number of particles (P = .001 and P = .013, respectively). CONCLUSIONS: The intra-aortic filter collects material during aortic manipulation. However, intraluminal aortic manipulation from filter handling can also dislodge particles, possibly related to shedding of intimal debris. This is in addition to substantial amounts of particles that are generated by aortic cannulation and aortic crossclamping.

Keyword
Aged, Aged; 80 and over, Aorta, Aortic Diseases/*complications, Atherosclerosis/*complications, Catheterization/adverse effects, Cerebrovascular Accident/prevention & control, Constriction, Female, Filtration/*instrumentation, Humans, Intracranial Embolism/*prevention & control, Male, Middle Aged, Particle Size, Risk Factors
Identifiers
urn:nbn:se:umu:diva-15326 (URN)10.1016/j.jtcvs.2005.10.015 (DOI)16434255 (PubMedID)
Available from: 2008-01-11 Created: 2008-01-11 Last updated: 2017-12-14Bibliographically approved
5. Aortic plaque distribution in relation to cross-clamp and cannulation procedures during cardiac surgery
Open this publication in new window or tab >>Aortic plaque distribution in relation to cross-clamp and cannulation procedures during cardiac surgery
2007 (English)In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 41, no 2, 120-125 p.Article in journal (Other academic) Published
Keyword
Age Factors, Aged, Aged; 80 and over, Aorta; Thoracic/*pathology/*surgery, Atherosclerosis/*pathology, Autopsy/*methods, Cadaver, Calcification; Physiologic, Cardiac Surgical Procedures/adverse effects/*methods, Catheterization/*methods, Cause of Death, Female, Humans, Male, Middle Aged, Stroke/etiology
Identifiers
urn:nbn:se:umu:diva-4808 (URN)17454838 (PubMedID)
Available from: 2005-11-16 Created: 2005-11-16 Last updated: 2017-12-14Bibliographically approved

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