Objectives: Cerebral complications continue to be a major cause of morbidity after cardiac surgery. Earlier studies have mainly focused on intraoperative events, but symptoms may also occur later in the postoperative period. The purpose of this study was to determine the incidence and risk factors of focal neurologic complications and timing of cerebral symptoms.

Design: A retrospective study.

Setting: Linköping University Hospital.

Participants: Two thousand four hundred eighty patients who underwent cardiac surgery from 1992 to 1995.

Interventions: Standard cardiopulmonary bypass (CPB) technique was used in all patients. Anticoagulant treatment included heparin and patients with coronary artery surgery were also administered acetylsalicylic acid and valve-surgery patients received warfarin or dicumarol.

Measurements and Main Results: Seventy-five patients (3%) had focal neurologic deficits and/or confusion postoperatively. In 32 patients (43%), the onset was not intraoperative but occurred later in the postoperative period. The lowest incidence of cerebral complications was found in patients who underwent single-valve replacement (1.2%) and the highest incidence was found in patients who underwent combined procedures (valve and coronary artery surgery; 7.6%). Patients greater than 70 years of age had a complication rate of 4.1% compared with 2.5% in patients aged 70 years and less (p < 0.05). The incidence of diabetes mellitus was 11.4% in the entire series, but was more common (18.7%; p < 0.05) in patients with cerebral symptoms. Also, 5.9% of all patients had a history of cerebrovascular disease compared with 14.7% (p < 0.01) of patients with cerebral complications.

Conclusion: Cerebral complications may be delayed after cardiac surgery, suggesting causes of cerebral damage other than intraoperative events. Valve-surgery patients had the lowest incidence and patients with combined procedures had the highest incidence of cerebral complications. Advanced age, diabetes mellitus, and preexisting cerebrovascular disease increased the risk.

Objective. To determine the long-term results of above-knee femoro-popliteal bypass with autologous saphenous vein (SV) or expanded polytetrafluoroethylene (ePTFE) in routine surgical practice. Methods. Data from the Swedish vascular registry, Swedvasc was reviewed retrospectively. Patients with bypass surgery in 1996 and 1997 were assessed 5-7 years later. Data were gathered from the case-records and from clinical follow-up. The composite endpoint of graft failure included death within 30 days, occlusion, major amputation, extension of the graft to below-knee position and removal of an infected graft. Kaplan-Meier curves and Cox' proportional hazard ratios were calculated. Results. Four hundred and ninety-nine patients undergoing bypass for critical limb ischemia (CLI) (56%) or claudication (44%), SV (28%) or ePTFE (72%), were included. There were no significant differences in patient characteristics between patients with SV or ePTFE. CLI and ePTFE were risk factors for graft failure. For patients with both claudication and CLI SV grafts yielded better long-term results than ePTFE grafts (p<0.03) and (p<0.003), respectively. Symptom aggravation after graft occlusion was almost exclusively restricted to ePTFE grafts. Conclusions. Femoro-popliteal bypass above-knee with SV gives good long-term results, especially for claudication. ePTFE grafts cannot be recommended in claudicants, since occlusion occurs often and frequently leads to CLI. © 2005 Elsevier Ltd. All rights reserved.

Perioperative myocardial infarction remains a major cause of morbidity and mortality after cardiac surgery. In spite of this there is no consensus regarding diagnostic criteria and consequently the reported incidence varies widely. In this thesis risk factors for PMI and outcome after PMI were studied in a retrospective case control study on 42 patients fulfilling strict criteria for PM! collected from a cohort of 1147 adult cardiac surgical patients. Traditional diagnostic criteria for PMI, release characteristics of biochemical markers for myocardial injury and VCG were evaluated in a prospective study on 302 consecutive patients undergoing isolated frrst time CABG. PM! was found to be a problem mainly associated with surgery for ischaemic heart disease. Unstable angina and unfavourable conditions for revascularisation were found to be the most important risk factors for PMI. Patients with PM! had an impaired short-term and mid-term outcome compared with controls. In the prospective study a sustained elevation of troponin-T was used as a marker for permanent myocardial damage. It was demonstrated that Q-wave criteria, previously accepted as the gold standard for diagnosis of PM!, correlated poorly with biochemical markers of myocardial injury and clinical outcome. One fourth of the patients with new Q-waves after CABG had no evidence of permanent myocardial injury. The use of biochemical markers for early diagnosis of myocardial injury is interfered by unspecific release unrelated to permanent myocardial damage. However, little is known about the magnitude of this "diagnostic noise". To address this issue a subgroup with no or minimal permanent myocardial damage was identified by use of the unique release characteristics of troponin-T. The time frame of unspecific release and the plasma levels of CKMB and troponin-T caused by unspecific release were assessed. A substantial early release of both CKMB and troponin-T nnrelated to permanent myocardial injury was found. As the unspecific release can be expected to differ depending on type of cardiac intervention this type of knowledge may prevent inappropriate comparisons. Repeated early sampling for CKMB provided additional information of value for early identification of patients who would later show sustained elevation of troponin-T. VCG was found to correlate better with sustained levels oftroponin-T and clinical outcome than scalar ECG. To conclude, diagnostic pitfalls associated with both ECG and enzymatic diagnosis of PM! were addressed and novel approaches to improve detection of permanent myocardial damage are suggested.

As previous efforts failed to reduce infection rates after cardiac surgery at our institution, we developed a concept based on adjustment of surgical technique. This concept was then evaluated in clinical practice. We modified our surgical technique towards: minimizing contamination, avoidance of devitalizing tissue, and securing a rigid fixation of the caudal part of sternum. After a pilot series sequential series was compared before and after introduction of the modified technique in a case-series design. All surgical site infections were recorded at discharge, after 6 weeks and by the attending cardiologist at 2 and 6 months. In the pilot series 9/136 patients developed sternal wound infections (SWI) compared with 15/89 patients in the control group (P=0.015). In the larger study population we found a significant drop in the total number of SWIs (72/772 vs 124/772, P≪0.0001). Although not statistically significant a 32% reduction in deep SWIs was observed. No reduction in infections at harvest sites for graft material was seen. The preliminary results from the pilot study appear reproducible and we were able to reduce the incidence of SWIs significantly, using this simple modified surgical technique.

Background: Release of biochemical markers of myocardial injury unrelated to permanent myocardial damage has been claimed to explain a major proportion of elevations seen after cardiac surgery. However, little is known about the magnitude of this unspecific release. The aim of this study was to shed light on this issue by serial measurements in patients without permanent myocardial injury after coronary surgery.

Methods: The unique release kinetics of troponin-T were employed to identify patients with no or minimal permanent myocardial injury. 302 patients undergoing CABG procedures (employing cardiopuhnonary bypass, crystalloid cardioplegia and retransfusion of shed mediastinal blood) were studied.

Results: 90 patients were found to have normalized troponin-T levels no later than the fourth postoperative day indicating that early elevation of biochemical markers was explained almost purely by unspecific release. In this subgroup troponin-T (2.03±1.36 µg/L; range 0.35-8.99 µg/L) peaked at the 3 hour recording and CK-MB (28.3±10.7 µg/L; range 11.9-86 µg/L) peaked at the 8 hour recording after unclamping the aorta.

Conclusions: A substantial early release of CK-MB and troponin-T occurred in patients with no or minimal permanent myocardial injury after CABG. The time frame when unspecific release was most pronounced is frequently studied to evaluate myocardial protective strategies or to compare different treatment modalities. Also, differences in unspecific release of biochemical markers can be expected depending on type of surgical procedure or coronary intervention. Therefore, further efforts to hring clarity about diagnostic pitfalls are warranted to prevent inappropriate comparisons and to improve our assessment of myocardial damage in association with revascularisation procedures.

Objective - ECG diagnosis of myocardial infarction after cardiac surgery is associated with major pitfalls and enzyme diagnosis is interfered by unspecific elevation unrelated to permanent myocardial injury. Sustained release of troponin-T is a marker of permanent myocardial injury if renal function is maintained. However, early identification of perioperative myocardial infarction is desirable and therefore the usefulness of creatine kinase monobasic (CK-MB) kinetics to detect myocardial injury early after coronary surgery was investigated.

Design - Two hundred and eighty-six patients undergoing coronary surgery were studied with respect to release of enzymes and troponin-T preoperatively and postoperatively 3 and 8 h after unclamping the aorta, and every morning postoperative days 1-4.

Results - CK-MB peak was found at 3 h ( n = 145), 8 h ( n = 103) and 16-20 h after unclamping ( n = 38). Depending on when the CK-MB peak was recorded different demographic and perioperative characteristics were found. A sustained release of troponin-T was characteristic for the group with the CK-MB peak at 16-20 h after unclamping.

Conclusion - If CK-MB is measured only once it may be advisable to do it on the first postoperative morning as these measurements provided the best discrimination between patients with and without sustained elevation of troponin-T. However, repeated sampling provides additional information that aids in the early identification of permanent myocardial injury particularly in patients with borderline elevations of CK-MB.

Objective - Biochemical markers of myocardial injury are frequently elevated after cardiac surgery. It is generally accepted that release unrelated to permanent myocardial damage explains a proportion of these elevations. However, little is known about the magnitude and temporal characteristics of this diagnostic noise. One way to address this issue would be to study a group without permanent myocardial injury. Design - The unique release kinetics of troponin-T (permanent myocardial injury causes a sustained release of structurally bound troponin) were used to identify patients with no or minimal permanent myocardial injury. Blood was sampled from patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) before surgery, 3 and 8 h after unclamping the aorta, and each morning until postoperative day 4, for analysis of enzymes and troponin-T. From 302 consecutive patients a subgroup was identified that fulfilled the following criteria: (a) normalized troponin-T levels =postoperative day 4, (b) no ECG changes indicating myocardial injury. Results - Seventy-seven patients fulfilled the criteria above and in this subgroup troponin-T (2.08 ▒ 1.42 ╡g/ 1, range 0.35-8.99 ╡g/l) peaked at the 3 h recording and creatine kinase monobasic (CK-MB) (28.6 ▒ 11.3 ╡g/l, range 11.9-86.0 ╡g/l) peaked at the 8 h recording after unclamping the aorta. Conclusion - Substantial early elevations of plasma CK-MB and troponin-T occurred in patients with no or minimal permanent myocardial injury after CABG. Unspecific release was most pronounced during the timeframe that is usually studied to evaluate myocardial protective strategies or to compare revascularization procedures.

Objective. The aim of the study was to analyze risk factors and clinical outcome in patients sustaining perioperative myocardial infarction (PMI) after cardiac surgery.

Design. A retrospective, case control study was conducted, in which 42 patients fulfilling both Q-wave criteria and enzyme criteria for PMI, or autopsy diagnosis, from a cohort of 1147 operated on during the same time period were compared with matched controls. A follow-up by telephone interview was conducted, on average 24 months after the operation.

Results. Unstable angina, peripheral vascular disease, short stature and low body weight were more prevalent in the PMI group. Intraoperative remarks of poor quality coronary vessels and incomplete revascularization were more frequent in the PMI group, 30-day mortality was 24% in the PMI group vs 0% in the control group (p < 0.01). The postoperative course was more complicated and protracted in the PMI group. At follow-up, the control group managed significantly better with regard to freedom from angina and the need for nitroglycerine. However, 24 of the 30 survivors in the PMI group reported an improved quality of life after surgery.

Conclusions. We found that PMI was mainly associated with coronary surgery and that unstable angina was the most important preoperative risk factor for PMI. Poorer conditions for revascularization may explain some of the infarcts and could also contribute to the impaired long-term outcome in the PMI group.

Cluster analysis is one way of data mining from large amounts of information. Being able to perform series of analyses, varying clinical criteria and requests, expected results of the clustering might be truly rewarding. Instead of having a few hypotheses prepared and tested, medical experts can be surprised by obtaining a set of hypotheses to further validate and work on.

Internet technologies enable a substantial flexibility that can be taken advantage of when implementing a Web-based tool. Division of Medical Informatics together with Linkoping Heart Center of the Linkoping University is developing procedures for multivariate clustering within the Web-based AssistMe1 system.

Objective

Sparing the aortic valve has become a surgical option for patients who require repair of aortic root ectasia and have normal valve leaflets. Surgical approaches to valve sparing differ with regard to preservation of the native sinuses of Valsalva. The role of the sinuses and the importance of maintaining them remain controversial.

Methods

By using a time-resolved, 3-dimensional, phase-contrast magnetic resonance imaging technique, aortic root and aortic blood velocity data were acquired from 2 patients with Marfan syndrome 6 months after aortic valve–sparing surgery with straight Dacron grafts and contrasted with data from 6 normal volunteers.

Results

In normal aortas vortical blood flow became apparent in the individual sinuses after peak systole. The vortices filled the available space behind the valve leaflets and persisted until diastole, expanding and moving inward during aortic valve closure. In contrast, no vortices were observed in the postoperative patients with Marfan syndrome with negligible sinuses.

Conclusions

Changes in supravalvular flow accompany loss of sinus architecture. Whether the presence, size, and velocity of supravalvular vortices affects the function or durability of the preserved aortic valve remains to be studied.

Objective - To determine how second generation pericardial valves perform in patients with small aortic roots. Design - Ninety patients who underwent isolated aortic valve replacement (AVR) with 19 or 21 mm Mitroflow« or Carpentier-Edwards (Perimount«) valves between 1989 and 1996 were studied. Mean age was 78 years. Concomitant coronary bypass surgery was performed in 41%. Results - Thirty-day mortality was 5.6%. Ninety-seven percent had acceptable transprosthetic mean pressure gradients (25 mmHg or less) 1 week after surgery. Follow-up was 100% complete and 76% of the patients were alive after a mean of 5 years. There was no structural valve failure or valve thrombosis. One patient required reoperation for perivalvular leak. Four patients had transient ischemic attacks and seven had strokes. These figures are, however, within the expected range for the age. Conclusion - Second generation pericardial valves perform well in elderly patients with small aortic roots. Postoperative hemodynamics are acceptable, valve durability of up to 8 years adequate, and the clinical results good, considering the age of the patients.

Background: The aim of the present study was to examine the influence of the number of sternal fixation wires used on deep sternal wound infection rate and to analyze any possible interaction between this and local collagen-gentamicin prophylaxis evaluated in a previous trial. Methods: The number of sternal fixation wires in all patients from one of two participating centers was counted. The patients were categorized according to six or fewer (standard technique, ST group) vs. seven or more wires (extra wires, XW group). Results: The incidence of deep sternal wound infection was 4.2% in the ST group and 0.4% in the XW group (p = 0.001). An analysis of the effect of local gentamicin, excluding the ST group from the analysis, showed an approximately 70% reduction in sternal wound infection for all depths. Conclusion: This study supports the theory that additional fixation wires at the lower sternum actually reduce the incidence of deep wound infections. We suggest that a rigid sternal fixation is required to achieve the full benefit of local collagen-gentamicin prophylaxis. © Georg Thieme Verlag KG.