Influence of more than six sternal fixation wires on the incidence of deep sternal wound infection.

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.

Unspecific elevation of plasma troponin-T and CK-MB after coronary surgery.

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 < or = 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 microg/l; range 0.35-8.99 microg/l) peaked at the 3 h recording and creatine kinase monobasic (CK-MB) (28.6 +/- 11.3 microg/l; range 11.9-86.0 microg/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.

Early identification of permanent myocardial damage after coronary surgery is aided by repeated measurements of CK-MB.

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.

Vectorcardiography is superior to conventional ECG for detection of myocardial injury after coronary surgery.

OBJECTIVE: The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. DESIGN: VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. RESULTS: Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. CONCLUSION: VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.

Lack of effect of synthetic pericardial substitute on right ventricular function after coronary artery bypass surgery. An echocardiographic and magnetic resonance imaging study.

Abnormal right heart function after cardiac surgery is a well-known finding. Inadequate preservation during the operation and restricted cardiac motion due to pericardial adhesions have been proposed as underlying mechanisms. This study focuses on the impact of a pericardial substitute implantation on right ventricular function, using echocardiography and magnetic resonance imaging. A test group of six patients (mean age 54 years) was examined before surgery, and 4-15 days and 5-9 months after coronary artery bypass surgery, where the pericardium was closed with a biodegradable pericardial patch. A group of 11 patients (mean age 63 years) in whom the pericardium was left open served as controls. Tricuspid annulus motion was markedly decreased, abnormal septal motion was present and decreased systolic to diastolic ratio in the vena cava superior flow was present in all patients in both groups one week after surgery. At the late follow-up, all patients still had decreased tricuspid annulus motion, while 17% of the patients in the test group and 22% of the patients in the control group (ns) demonstrated normal septal motion. We conclude that closing the pericardium with a biodegradable patch does not affect the postoperative changes in right heart function normally seen after open-heart surgery.

Perioperative myocardial infarction in cardiac surgery--risk factors and consequences. A case control study.

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.

Are electrocardiographic Q-wave criteria reliable for diagnosis of perioperative myocardial infarction after coronary surgery?

OBJECTIVE: A major assumption in cardiovascular medicine is that Q-waves on the electrocardiogram indicate major myocardial tissue damage. The appearance of a new Q-wave has therefore been considered the most reliable criterion for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery. In a study, originally intended to evaluate troponin-T as a marker of PMI, analysis of our data aroused the need to address the reliability of Q-wave criteria for diagnosis of PMI. METHODS: In 302 consecutive patients undergoing coronary surgery, Q-wave and other electrocardiogram (ECG) criteria were compared with biochemical markers of myocardial injury and the postoperative course. All ECGs were analysed by a cardiologist blinded to the biochemical analyses and the clinical course. RESULTS: The incidence of positive Q-wave criteria was 8.1%. Combined biochemical (CK-MB > or = 70 microg/l) and Q-wave criteria were found in 1.0%. Patients with new Q-waves did not have CK-MB or troponin-T levels significantly different from those without Q-waves. More than 25% of the Q-waves were associated with plasma troponin-T below the reference level (< 0.2 microg/l) on the fourth postoperative day. Q-wave criteria alone did not influence the postoperative course. In contrast, biochemical markers correlated with clinical outcome. CONCLUSIONS: The majority of Q-waves appearing after coronary surgery were not associated with major myocardial tissue damage, and according to troponin-T one-fourth of the Q-waves were not associated with myocardial necrosis. Furthermore, the appearance of Q-waves had little influence on short term clinical outcome. Therefore, the use of Q-wave criteria as the gold standard for diagnosis of PMI may have to be questioned.

Bacteremia associated with extracorporeal shockwave lithotripsy of gallbladder stones.

BACKGROUND/AIMS: The possible induction of bacteremia by extracorporeal shock wave lithotripsy (ESWL) of gallbladder stones was studied. MATERIALS AND METHODS: Seventy-six patients undergoing a total of 107 ESWL treatments were studied. RESULTS: Twenty-four (22%) of the 107 treatments were associated with bacteremia. Staphylococcus epidermidis was cultured during and/or after 23 (96%) of the treatments associated with bacteremia. The ESWL-induced tissue damage of the skin in the pass-way of the shock-waves was the most likely cause of bacteremia in these patients. There was no correlation between the occurrence of bacteremia and the age or body mass index of the patients. Neither was there any correlation of bacteremia related to the duration of the treatment, the number of shock waves, the energy delivered, the stone volume or the occurrence of calcified stones. No patient developed sepsis or endocarditis. Transient fever shortly after treatment was recorded in 5 patients (5%), one of whom had bacteremia. CONCLUSIONS: Routine antibiotic prophylaxis is not indicated in patients undergoing ESWL for gallbladder stones. The question whether such prophylaxis should be given to patients at special risk, for instance patients with artificial heart valves or known valvular heart disease, remains to be answered in larger controlled and randomized studies.

Trends in incidence, clinical findings and outcome of acute and elective cholecystectomy, 1970-1986.

OBJECTIVE: To assess time trends in the incidence, clinical findings, and outcome of conventional acute and elective cholecystectomy. DESIGN: Single-institution time series analysis. SETTING: University hospital, Sweden. SUBJECTS: A consecutive series of 2926 patients operated on for acute or chronic gallbladder disease in a defined Swedish population. MAIN OUTCOME MEASURES: Changes in the incidence and outcome of acute and elective cholecystectomy. RESULTS: From period I (1970-1978) to period II (1979-1986), the mean rate of acute operations increased from 10 to 30/100,000 inhabitants/year and that of elective operations decreased from 190 to 120/100,000 inhabitants/year. There was therefore a negative correlation between the rate of elective and acute operations (r = -0.58, p < 0.02). This was strongest when the rate of elective operations in any one year was correlated with the rate of acute operations two years later (r = -0.71, p < 0.01). In both groups the proportion of patients over 70 years old increased significantly. The female:male ratio decreased significantly for acute but not elective operations (mean 2.6 in period I and 1.0 in period II). The length of history and the number of previous admissions to hospital with gallstone disease decreased significantly for both groups, as did prevalence of common bile duct stones detected at cholecystectomy. Morbidity did not seem to change, though a general improvement may have been concealed, because patients were older in period II and postoperative mortality was lower than in period I. Complications were least common among patients with a short or no previous history of symptoms attributable to gallstones. CONCLUSIONS: The rate of elective cholecystectomy seems to have some influence on the future rate of acute cholecystectomy. When symptoms of gallstone disease develop, treatment should not be delayed unnecessarily.

Long-term follow-up of patients with gallbladder in situ after endoscopic sphincterotomy for choledocholithiasis.

Endoscopic sphincterotomy (EST) was performed on 148 patients with common bile duct stones and intact gallbladder. The duct was cleared in 130 cases (88%). Immediate complications occurred in 23 patients (15.5%), six of whom died. In 118 of the 139 patients discharged from the hospital, the bile ducts were cleared and the gallbladder in situ. The median observation time in these 118 cases was 42 (1-97) months, during which 13 (11%) were cholecystectomized because of symptoms or acute complications due to remaining gallbladder stones, and 49 (42%) died 2-87 (median 24) months after EST. The probability (life-table) of remaining free from cholecystectomy-requiring symptoms or complications was 0.87 after 42 months. There was no association between nonfilling of the gallbladder at ERC and subsequent problems with gallbladder stones. EST for choledocholithiasis with retained gallbladder is justified for elderly and frail patients. Indefinite postponement of cholecystectomy may be warrantable, restricting surgery to patients with symptoms from gallbladder stones. This most frequently means within 2 years after EST.