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Size distribution of embolic material produced at aortic cross-clamp manipulation
Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Kirurgi.
2010 (Engelska)Ingår i: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 44, nr 6, s. 367-372Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Objectives: The association between aortic atherosclerosis and neurological damage during cardiac surgery is well recognized. The purpose was here to analyze the size distribution of particles produced at cross-clamp manipulation of the ascending aorta.

Design: A human cadaveric aortic perfusion model of retrograde design was applied (n 27). With this model, washout samples were collected from the pressurized ascending aorta during cross clamp manipulation. Before the experiment, the aorta was flushed to remove debris and with a baseline sample collected. The cross-clamp was opened to collect ten repeated aliquots with dislodged particles. Collected washout samples were evaluated by digital image analysis and microscopy.

Results: Cross-clamping produced a significant output of particles, which was seen for size intervals of 1 mm and smaller (p 0.002 to p 0.022). In all size intervals the particle output correlated with the degree of overall aortic calcification(p 0.002 to p 0.025). The model generated substantially more small-size particles than large debris (p 0.010).

Conclusions: Aortic clamping was here verified to dislodge aortic debris which correlated with the degree of observed calcification. Macroscopic particles were few. In contrast, cross-clamping produced substantial numbers of small-size particles. These findings emphasize microembolic risks associated with cross-clamping of atherosclerotic vessels.

Ort, förlag, år, upplaga, sidor
London, UK: Informa Plc. , 2010. Vol. 44, nr 6, s. 367-372
Nyckelord [en]
Cardiac surgery, aorta, atherosclerosis, surgical clamp, embolism, stroke
Nationell ämneskategori
Kirurgi
Forskningsämne
kirurgi, särskilt thoraxkirurgi
Identifikatorer
URN: urn:nbn:se:umu:diva-38073DOI: 10.3109/14017431.2010.501867OAI: oai:DiVA.org:umu-38073DiVA, id: diva2:372208
Tillgänglig från: 2010-11-24 Skapad: 2010-11-24 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Ingår i avhandling
1. Stroke during cardiac surgery: risk factors, mechanisms and survival effects
Öppna denna publikation i ny flik eller fönster >>Stroke during cardiac surgery: risk factors, mechanisms and survival effects
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Stroke i samband med hjärtkirurgi : riskfaktorer, mekanismer och effekter på överlevnad
Abstract [en]

Introduction: Neurological complications and stroke in association with cardiac surgery is a serious problem. The stroke event can occur during surgery (early stroke) or in the postoperative period with a symptom free interval (delayed stroke). Particle embolization due to aortic manipulation during surgery has been suspected as a mechanism for early stroke. The present thesis address mechanisms and survival effects of stroke both clinically (I-III) and experimentally (IV-V).

Methods: Study I) Within a cohort of 2641 consecutive cases, a group of cardiac surgery patients with stroke and evaluated by computed tomography (CT) were studied (n=77). CT-findings were analyzed in relation to stroke symptoms. Study II) Data from 9122 patients undergoing coronary surgery were analyzed. Records of patients with any signs of neurological complications were reviewed to extract 149 subjects with stroke at extubation (early, 1.6%) versus 99 patients having a free interval (delayed, 1.1%). Early and delayed stroke were evaluated separately. Independent risk factors for stroke were analyzed by logistic regression and survival by Cox regression (9.3 years median follow-up). Study III) Patients with early (n=223) and delayed stroke (n=116) were identified among 10809 patients undergoing cardiac and aortic surgery, both groups exposed to cardiopulmonary bypass. Stroke patients were subdivided by the hemispheric location of lesions. Subgroups were compared and their associated pre- and peroperative variables and survival were analyzed. Study IV) Aortic cross-clamp manipulation was studied in a human cadaveric perfusion model. The pressurized aorta was repeatedly cross-clamped and washout samples were collected before and after clamp maneuvers. Particles in the washout samples were evaluated by microscopy and by digital image analysis. Study V) Pig aortas were pressurized and cannulated. Washout samples were collected before and after cannulation (n = 40). Particles were deposited onto a 10-μm filter to be evaluated by microscopy and digital image analysis.

Results: Study I) In the group of patients exposed to routine cardiac surgery (i.e., clamping and cannulation) and with early stroke, right-hemispheric lesions were more frequent than of the contra-lateral side (P=0.005). Patients with aortic dissections had a strong dominance of bilateral findings, which was different from the unilateral pattern in the routine-surgery group (P<0.001). Study II) Early and delayed stroke did not share any risk factors. Both early and delayed stroke explained mortality in the early postoperative period (P<0.001, P<0.001 respectively) but also at long term follow-up (P=0.008, P<0.001 respectively). For patients surviving their first postoperative year, delayed but not early stroke influenced long-term mortality (P=0.001 and P=0.695, respectively). Study III) Stroke lesions in association to cardiac surgery were near exclusively ischemic. Early stroke had a preponderance for right-hemispheric lesions (P=0.009). In contrast, patients with early stroke that had undergone surgery of the aorta with circulatory arrest showed a pattern with more bilateral lesions compared to ‘cardiac-type’ operations (P<0.001). Patients with bilateral lesions had a dramatically impaired survival compared to those with unilateral lesions (P<0.001). Study IV) In the cadaveric perfusion model, cross-clamping produced a significant output of particles, which was seen for size intervals of 1 mm and smaller (P=0.002 to P=0.022). In all size intervals the particle output correlated with the degree of overall aortic calcification (P =0.002 to P=0.025). Study V) At cannulation of the pig aorta, more particles were noted after cannulation compared to before the maneuver (P<0.001). This increase included small (<0.1 mm, P<0.001) and intermediate-size particles (0.1-0.5 mm, P< 0.001). Particles above 0.5 mm were few and were not associated with cannulation.

Conclusions: The influence of stroke on mortality was devastating, for both early and delayed stroke. These two stroke groups had obvious differences in both their risk factors and their hemispheric distribution. It is here emphasized that early and delayed stroke should be considered as two separate entities with suggested mechanistic differences. Ischemic lesions accounted for near all stroke events seen in association to cardiac surgery. For early stroke, these were mostly located within the right hemisphere. Results from the experimental studies underscore microembolic risks associated with aortic manipulation.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2010. s. 40
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1392
Nyckelord
stroke; cardiac surgery; adult; risk factors; mortality; embolism; aortic cross-clamp; aortic cannulation
Nationell ämneskategori
Kirurgi
Forskningsämne
kirurgi, särskilt thoraxkirurgi
Identifikatorer
urn:nbn:se:umu:diva-38079 (URN)978-91-7459-120-0 (ISBN)
Disputation
2010-12-17, Sal B, Tandläkarhögskolan, 9 tr, Norrlands universitetssjukhus, Umeå, 09:00 (Svenska)
Opponent
Handledare
Tillgänglig från: 2010-12-03 Skapad: 2010-11-24 Senast uppdaterad: 2018-06-08Bibliografiskt granskad

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Förlagets fulltexthttp://informahealthcare.com/doi/abs/10.3109/14017431.2010.501867

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Boivie, PatrikHedberg, MagnusEngström, Karl Gunnar

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