A 10-year retrospective study of infective endocarditis at a university hospital with special regard to the timing of surgical evaluation in S. viridans endocarditis.

A total of 154 episodes of infective endocarditis (IE) in 149 patients were studied retrospectively with special regard to the major aetiological groups and the surgical evaluation. There were 136 episodes of native valve endocarditis (NVE) (88%) and 18 episodes of prosthetic valve endocarditis (PVE) (12%). Three major groups of NVE crystallized: Streptococcus viridans in 37 (27%), Staphylococcus aureus in 39 (29%) and culture negative IE in 28 (21%) episodes. In these groups surgery during the active phase was required in 41, 28 and 18%, respectively. At the operation myocardial abscess was found in as many as 7/15 cases with S. viridans, but in only in 3/11 cases with S. aureus and 1/5 cases with culture negative IE. The mean duration of preoperative antibiotic treatment was 34 d. This long period of unsuccessful pharmacotherapy, preceded by a mean of 47 d from start of symptoms to admission to hospital, has probably resulted in the high frequency of myocardial abscess in S. viridans NVE. Surgical evaluation should be considered when fever persists beyond 10 d of adequate treatment, even in the absence of clinically apparent complications. Among the PVE episodes, 11/18 were managed with pharmacological treatment alone. Uncomplicated PVE may thus often be successfully treated with antibiotics alone.

Pericarbon pericardial valve prosthesis: midterm results of the aortic valve replacement.

This clinical study was undertaken to verify the encouraging results of experimental studies regarding a new pericardial bioprosthesis. From May 1989 to November 1993, 204 patients underwent an aortic valve replacement with the Pericarbon (Sorin Biomedica Cardio S.p.A., Saluggia, Italy) prosthesis. A follow-up was 100% complete and extended to 65 months (total 408 patient-years, average 2.0+/-1.4 years). Mean age at the operation was 75.1+/-5.5 years and 96% were in NYHA clinical stage III or IV. There were 86 men and 118 women; 73 patients had an isolated aortic valve disease, 131 had a concomitant cardiosurgical procedure (coronary artery bypass grafting in 106 patients). The operative mortality (30-day mortality) rate was 11.8% (24/204). There were 24 late deaths (5.9+/-1.2% patient-year). The actuarial probability of survival was 68+/-5% at 5 years. Four patients died of valve-related causes (one thromboembolic complication, two endocarditis, one anticoagulant-related hemorrhage). Actuarial rate of freedom from valve-related death was 95+/-3% at 5 years. Valve-related morbidity included seven thromboembolic episodes (1.7% patient-year), four anticoagulant-related complications (0.9% patient-year), three endocarditis (0.7% patient-year) and one reoperation (0.2% patient-year). After 5 years freedom from thromboembolic events was 83+/-7%, from anticoagulant-related hemorrhage 96+/-2%, from endocarditis 97+/-2%, and from reoperation 99+/-1%. Echocardiographic study performed in 30 patients showed a paraprosthetic leak in four patients, a central leak in two, and cusp thickening in another three. The clinical data showed that the Pericarbon prosthesis has valve-related morbidity. The echocardiographic results suggest that the prosthesis can undergo a pathologic process during the first 5 years after implantation. This makes it necessary to continue the follow-up and include the larger number of patients in the echocardiographic investigation.

Sternal wound complications--incidence, microbiology and risk factors.

OBJECTIVE: Sternal wound complications, i.e. instability and/or infection (mediastinitis), are important causes of morbidity in patients undergoing cardiac surgery via median sternotomy. Coagulase negative staphylococci, a normal inhabitant of the skin, have evolved as a cause of sternal wound infections. Since these opportunistic pathogens often are multiresistant, they can cause therapeutic problems. METHODS: From 1980 through 1995 open heart surgery, was performed on 13,285 adult patients. Reoperation necessitated by sternal wound complications occurerd in 203 patients (1.5%). The incidence was 1.7% (168/9987) after coronary artery bypass grafting (CABG group) and 0.7% (35/3413) after heart valve surgery with or without concomitant CABG (HVR group). RESULTS: Factors independently related to sternal complications in the CABG group (variable odds ratio [95% C.I.]): year of surgery, 1.9 [1.3-2.8] in 1990-1992, 2.0 [1.4-2.9] in 1993-1995; female sex, 0.4 [0.2-0.6]; diabetic disease, 1.8 [1.2-2.5]; bilateral ITA procedure, 3.3 [1.1-7.7]; and postoperative dialysis, 3.1 [1.4-6.9]. In the HVR group they were: use of ITA graft, 3.7 [1.7-7.7]; early re-exploration because of bleeding 3.0 [1.1-8.2]; and postoperative dialysis 3.1, [1.4-9.3]. Multivariate models were used to compute the risk for sternal complications in each patient. However, the prognostic models based on these risk scores provided low sensitivity and low predictive value. Patients with sternal wound complications showed no increased early mortality but worse long-term survival even after adjustment for other factors (relative hazard in CABG group 1.9 [1.2-2.8]; in HVR group 2.1 [1.1-4.3]. CONCLUSIONS: The use of ITA grafts seems to be one of the most important factors related to sternal wound complications. However, patients at truly increased risk for this complication could not be identified on the basis of the risk factors considered in this study.

Long-term relative survival after primary heart valve replacement.

OBJECTIVE: Determination of the optimal timing of primary heart valve replacement is an important issue. The present paper provides a synopsis over early and late survival after primary heart valve replacement, including an evaluation of the excess mortality among heart valve replacement patients compared with the general population. METHODS: Survival was analyzed in 2365 patients (1568 without and 797 with concomitant coronary artery bypass grafting (CABG)) who underwent their first heart valve replacement. Observed survival was related to that expected among persons from the general Swedish population stratified by age, sex, and 5-year calendar period, to calculate the relative survival and estimate the disease-specific survival. RESULTS: Early mortality (death within 30 days after surgery) was 5.9% after aortic valve replacement, 10.4% after mitral valve replacement and 10.6% after combined aortic and mitral valve replacement. Relative survival rates (excluding early deaths) were 84% 10 years after aortic, 68.5% after mitral and 80.9% after both aortic and mitral valve replacement. A multivariate model based on observed survival rates was produced for each group, using the Cox proportional hazards model. Concomitant CABG, advanced New York Heart Association (NYHA) class, preoperative atrial fibrillation, pure aortic regurgitation and higher age increased the late observed survival after aortic valve replacement. NYHA class was the only factor independently related to observed late deaths after mitral valve replacement, and mitral insufficiency the only corresponding factor after both aortic and mitral valve surgery. CONCLUSION: The use of relative survival rates tended to modify the difference between subgroups compared with observed survival rates. Relative survival rates reduced the effect of concomitant CABG on survival, but enhanced for example the effect of aortic regurgitation. In patients > or = 70 years of age and patients submitted to aortic or mitral valve replacement with mild or no symptoms, the survival rate was similar for many years to that in the Swedish population at large.

Acute renal failure and outcome of continuous arteriovenous hemodialysis (CAVHD) and continuous hemofiltration (CAVH) in elderly patients following cardiovascular surgery.

A total of 111 elderly patients from the cardiac surgery intensive care unit (ICU) with acute renal failure (ARF) were studied during a period of 7 years (1988-1994). Forty-two patients being operated for coronary bypass (CBP) (31 M, 11 F), 26 patients for valve replacement (VR) (18 M, 8 F), 20 patients for a combined operation of coronary bypass and valve replacement (CBP+VR) (14 M, 6 F) and 23 patients for resection of aneurysm of the abdominal aorta (ROAOAA) (11 M, 12 F). Average age of the patients was 70 +/- 4 yr (65-80). Their blood pressure on the first day of continuous renal replacement therapy (CRRT) was 75 +/- 19 mmHg (50-95) and was maintained at about 95 +/- 15 mmHg (70-120) by using vasopressor drugs. From the results of this study a survival of 38% was registered within the CBP group, 65% within the VR group, 45% within the CBP+VR group and 91% within the ROAOAA group. The overall survival in all of the patients was 58%. It was a high mortality (62%) within CBP group compared to that of 35%, 55% and 9% within the VR, CBP+VR and ROAOAA groups, respectively. This is because more patients with predisposing preoperative risk factors, e.g., hypertension (33%) and Diabetes (17%) etc were found in the CBP group, in addition to their post operative complications of which bleeding necessitating reoperations was encountered in 31%. Multiple organ failure (MOF) was a common major problem of which respiratory failure needing artificial ventilation was encountered in about 90% of the patients. The overall mortality was 42% in which the major cause of death was MOF/circulatory failure. Heart failure was the second cause of death. Other secondary complications, e.g., liver failure (n = 6) and atrial fibrillation (n = 11) etc. might have added to the high mortality in this study. The effect of CRRT on uremic control was measured by following-up of the daily levels of the serum urea and creatinine and a steady-state uremic control was achieved. We conclude that CRRT can be considered as a reliable artificial renal support for ARF in ICU elderly patients.

Survival after coronary artery bypass grafting. Experience from 4661 patients.

The duration of the reduction of mortality after coronary artery bypass grafting (CABG) is an important issue and this study was undertaken to evaluate time in relation to excess mortality among CABG patients compared with the general population. Survival was analysed in 4661 patients who had undergone their first isolated CABG. Observed survival was related to that expected among subjects from the general Swedish population stratified by age, sex and 5-year calendar period, to calculate relative survival and estimate disease-specific survival. Relative survival (including all deaths) was 94.6% at 5 years, 82.5% at 10 years, and 59.9% at 15 years. A multivariate model based on relative survival rates adjusted for age, year of surgery, severity of coronary disease, left ventricular function, and smoking habits was used. Compared with the first year of follow-up, the relative hazard (a measure of the risk of death) was at a minimum 2 years after surgery, but was dramatically increased after about 8 years. Relative survival was worsened by smoking at the time of operation and by moderate or severe left ventricular dysfunction pre-operatively. The survival rate was higher among patients operated on after 1985 than among those operated on earlier.

Low-molecular-weight heparin (Fragmin) versus heparin for anticoagulation during cardiopulmonary bypass in open heart surgery, using a pig model.

Fragmin and heparin were studied in pigs during 120 min of cardiopulmonary bypass (CPB) and up to 240 min postoperatively, with respect to clotting, bleeding and the effects of protamine. Thirty-three pigs received bolus injections of 300 IU/kg with or without additional dosage during CPB and with or without subsequent protamine sulphate. Doses of Fragmin 60% higher were necessary to prevent clotting. These had 100% higher anti-FXa levels but about 50% shorter activated coagulation time (ACT) compared with heparin. Anti-FXa increased with cumulative doses of heparin and Fragmin but ACT and activated partial thromboplastin time (aPTT) did not, indicating a larger loss of thrombin inhibition compared with anti-FXa in both drugs during CPB. Thrombin inhibition was crucial for prevention of clotting. Protamine efficiently normalized ACT in the Fragmin group but left a residual 20% anti-FXa, which did not increase the bleeding tendency. Fragmin could adequately be monitored with ACT and would be a safe alternative to heparin in CPB.

Fragmin (LMWH) vs heparin for anticoagulation during in vitro recycling of human blood in cardiopulmonary bypass circuits: dose-dependence and mechanisms of clotting.

Low-molecular-weight heparin (LMWH) (Fragmin) vs heparin was studied in vitro in order to investigate its antithrombotic efficacy in the isolated thrombogenic link of cardiopulmonary bypass (CPB). Fresh human blood (400 ml) with various dosages of the anticoagulant was recycled in a CPB circuit for 120 min. The standard dosage of heparin (1,500 IU, n = 6) was compared with a lower dosage (1,000 IU, n = 3) and several dosages of Fragmin (IU anti-FXa): 750 (n = 1), 1,500 (n = 3), 2,100 (n = 4) and 2,500 (n = 3). Clotting occurred in three Fragmin experiments at dosages of 750, 1,500 and 2,100 IU. This was associated with short activated clotting time (ACT) and activated partial thromboplastin time (aPTT) but was independent of the levels of anti-FXa, FVIII, von Willebrand factor and prothrombin complex. It was concluded that at least twice the dose of Fragmin (anti-FXa), compared with heparin, was required, suggesting that thrombin inhibition is crucial for the antithrombotic efficacy of heparin in CPB circuits. Absence of fibrinolytic markers suggests that the well known enhancement of fibrinolysis often seen during CPB, is not due to heparin interaction with normally circulating blood components, but rather to interaction with the vessel walls or to the surgical trauma itself.

Ventilation-perfusion inequality in patients undergoing cardiac surgery.

BACKGROUND: Impaired gas exchange is a major complication after cardiac surgery with the use of extracorporeal circulation. Blood gas analysis gives little information on underlying mechanisms, in particular if the impairment is multifactorial. In the current study we used the multiple inert gas technique with recordings of hemodynamics to analyze the separate effects of intrapulmonary shunt (QS/QT), ventilation-perfusion (VA/Q) mismatch, and low mixed venous oxygen tension on arterial oxygenation during cardiac surgery. METHODS: VA/Q distribution was studied in nine patients undergoing coronary artery revascularization surgery. The obtained data related to VA/Q distribution were perfusion of lung regions with VA/Q < 0.005 (QS/QT), perfusion of lung regions with 0.005 < VA/Q < 0.1 ("low"-VA/Q regions), ventilation of lung regions with 10 < VA/Q < 100 ("high"-VA/Q regions), and ventilation of lung regions with VA/Q > 100 (dead space [VD/VT]). In addition, arterial and mixed venous oxygen and carbon dioxide tensions and systemic and pulmonary hemodynamics were analyzed. Recordings were made before and after induction of anesthesia, after sternotomy, 45 min after separation from extracorporeal circulation, 4 h postoperatively during mechanical ventilation, and on the 1st postoperative day during spontaneous breathing. RESULTS: In the awake state, QS/QT was 4 +/- 4%, and perfusion of low-VA/Q regions was 3 +/- 5%. The sum of QS/QT and low-VA/Q units correlated with the alveolar-arterial oxygen tension gradient (PA-aO2) (r = 0.63, P < 0.05). After induction of anesthesia, QS/QT increased to 10 +/- 9% (P = 0.069). Sternotomy had little effect on shunt, but QS/QT increased to 22 +/- 8% (P < 0.01) after separation from extracorporeal circulation, which was correlated with a significantly higher PA-aO2 (r = 0.77, P < 0.05). Postoperatively, gas exchange improved rapidly, as assessed by a decrease of PA-aO2 from 341 +/- 77 to 97 +/- 36 mmHg (P < 0.01) and a reduced QS/QT (5 +/- 4%, P < 0.05). On the 1st postoperative day, arterial oxygen tension was significantly lower than preanesthesia values (58 +/- 6 vs. 68 +/- 8 mmHg, P < 0.05). QS/QT had increased to 11 +/- 6% (P < 0.05), but little perfusion of low-VA/Q units was observed. A correlation was found between PA-aO2 and QS/QT (r = 0.82, P < 0.03). CONCLUSIONS: QS/QT is a major component of impaired gas exchange before, during, and after cardiac surgery. QS/QT increases after induction of general anesthesia, probably because of development of atelectasis. After separation from extracorporeal circulation, accumulation of extravascular lung water or further collapse of lung tissue may aggravate QS/QT. Postoperatively, oxygenation improves, possibly because of recruitment of previously nonventilated alveoli or resolution of extravascular lung water. During spontaneous breathing, additional mechanisms such as altered mechanics of the chest, perfusion of low-VA/Q regions, and decreased mixed venous oxygen tension may contribute to impaired gas exchange.

Mitral valve prosthetic implantation with preservation of native mitral valve apparatus.

To avoid postoperative morbidity and mortality often associated with left ventricular dysfunction after mitral valve replacement (MVR) for chronic mitral insufficiency, reconstruction or preservation of the native mitral valve apparatus may be attempted during mitral prosthetic implantation (MPI). The effects of mitral surgery on heart function, studied with echocardiography and radionuclide angiography, were compared in seven patients with MPI (study group) and five with MVR (control group) who underwent complete preoperative, early postoperative and 3-6 months follow-up examinations. Preoperatively there was significant intergroup difference only in right ventricular ejection fraction measured at radionuclide angiography, which was lower in the MPI group (p < 0.05). At follow-up the MPI group had improved as regards this fraction (p < 0.005) and stroke volume index (p < 0.05). The number of patients with improved NYHA class at follow-up was significantly greater in the MPI group. Our preliminary experience with preservation of the native mitral valve apparatus thus suggests that the method offers haemodynamic advantages for postoperative right ventricular function.

Surgical treatment of left ventricular aneurysm--assessment of risk factors for early and late mortality.

Consecutive patients operated on for left ventricular aneurysm from 1970 through August 1989 (n = 303) were evaluated with respect to survival. Early mortality, i.e. within 30 days, was 8.9%; 23% in patients who underwent aneurysm resection alone, 8.1% in cases of aneurysm resection with coronary artery bypass grafting (CABG), and 6.3% in those undergoing CABG only. Multivariate logistic regression revealed that advanced New York Heart Association (NYHA) functional class, non-use of the internal mammary artery as a graft and thromboendarterectomy increased the early risk. The total observed survival was 86% at 1 year, 72% at 5 years and 45% at 10 years. Multivariate analysis based on observed survival, using the Cox proportional hazards model, identified advanced NYHA functional class and non-use of the internal mammary artery as independent indicators of poor survival. Relative mortality, defined as the ratio of observed mortality in the study group to mortality among comparable persons from the general Swedish population, was used as a measure of disease-specific mortality. An apparent excess mortality in patients operated on for left ventricular aneurysm was found. A notable finding was that the use of the internal mammary artery to graft the left anterior descending artery improved the outcome substantially in patients with a left ventricular aneurysm.

Thoracic intravascular and extravascular fluid volumes in cardiac surgical patients.

BACKGROUND: One possible mechanism of impaired oxygenation in cardiac surgery with extracorporeal circulation (ECC) is the accumulation of extravascular lung water (EVLW). Intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) also may increase after separation from ECC, which can influence both cardiac performance and pulmonary capillary fluid filtration. This study tested whether there were any relationships between lung fluid accumulation and pulmonary gas exchange during the perioperative period of cardiac surgery and ECC. METHODS: Ten patients undergoing myocardial revascularization were studied. ITBV, PBV, and EVLW were determined from the mean transit times and decay times of the dye and thermal indicator curves obtained simultaneously in the descending aorta. Gas exchange was assessed by arterial and mixed venous partial pressure of oxygen (PO2) and carbon dioxide (PCO2), and calculation of alveolo-arterial PO2 gradient (PA-aO2) and venous admixture (QVA/QT). Recordings were made after induction of anesthesia, after sternotomy, 15 min after separation from ECC, and 4 and 20 h postoperatively. RESULTS: After induction of anesthesia, EVLW (6.0 +/- 1.0 ml/kg, mean +/- SD), PBV (3.6 +/- 1.3 ml/kg), and ITBV (18.4 +/- 2.7 ml/kg) were within normal ranges. Oxygenation was moderately impaired, as indicated by an increased PA-aO2 (144 +/- 46 mmHg) and QVA/QT (11 +/- 4%). After separation from ECC, EVLW had increased to 9.1 +/- 2.6 ml/kg, which was accompanied by an increase of ITBV (26.0 +/- 4.4 ml/kg) and PBV (5.6 +/- 1.9 ml/kg). PAa-O2 (396 +/- 116 mmHg) and QVA/QT (29 +/- 7%) also were increased. ITBV and PBV remained increased 4 and 20 h postoperatively, but EVLW decreased to presurgery values. No correlations were found between thoracic intravascular and extravascular fluid volumes and gas exchange. CONCLUSIONS: Cardiac surgery with the use of ECC induces alterations of thoracic intravascular and extravascular fluid volumes. Postoperatively, increased ITBV and PBV need not be associated with higher EVLW. Thus, sufficient mechanisms protecting against lung edema formation or providing resolution of EVLW probably are maintained after ECC. Since oxygenation is impaired during and after cardiac surgery, it is concluded that mechanisms other than or in addition to changes of ITBV, PBV, and EVLW predominantly influence gas exchange.

High-dose intravenous beta 1-blockade in patients early after cardiac operations. Negative inotropism versus myocardial oxygen economy.

A high adrenergic strain during reperfusion after ischemia impedes functional recovery. Conversely, adrenergic blockade may be beneficial during reperfusion. Negative inotropic effects may outweigh the expected benefit, however. Against this background hemodynamic and metabolic effects of early postoperative infusion with the beta 1-selective agent metoprolol were studied in 22 patients after coronary operations. During basal postoperative conditions, intravenous metoprolol reduced cardiac index and stroke volume index compared with control patients, while other variables were unaffected. During the higher adrenergic level of a dopamine infusion (7 micrograms/kg per minute), the heart rate, rate pressure product, and myocardial oxygen uptake were attenuated in proportion to the plasma level of metoprolol. Intravenous beta 1-blockade did not affect the cardiac output or stroke volume responses to dopamine (the cardiac output was still, however, 19% lower than in control patients). A release of myocardial creatinine kinase isoenzyme myocardial band was observed during dopamine infusion, suggesting that myocardial ischemia was induced. The release was not influenced by metoprolol, but it correlated with heart rate (r = 0.60; p < 0.01). It is concluded that infusion of metoprolol early after coronary operations depresses myocardial contractility with some 19%, which was without clinical significance in straightforward patients; the increased myocardial metabolic demand during a period of increased adrenergic stress was attenuated by metoprolol. This may be of importance for myocardial recovery.

Influence of beta 1-blockade on myocardial substrates early after a coronary operation.

A high adrenergic strain during reperfusion after ischemia impedes functional recovery. Conversely, adrenergic blockade may be beneficial during reperfusion. This study was undertaken to find out if early postoperative high-dose infusion of the selective beta 1-blocking agent metoprolol tartrate has additional effects on metabolic variables related to myocardial energy supply/demand balance compared with those obtained with a late preoperative oral dose. The study included 21 male patients undergoing coronary bypass grafting. All patients received an oral dose of metoprolol before the operation. After the operation, patients were randomized to a control group or a group receiving intravenous infusion of metoprolol. Myocardial uptake of oxygen and substrates was determined before and during atrial pacing. Metoprolol reduced arterial concentrations of free fatty acids, reduced myocardial uptake of free fatty acids, and enhanced myocardial uptake of lactate. During paced tachycardia, the metoprolol concentration correlated negatively with myocardial uptake of free fatty acids (r = -0.80; p < 0.001) and positively with myocardial uptake of lactate (r = 0.53; p < 0.05). It is concluded that postoperative infusion of metoprolol induces myocardial metabolic changes compatible with an improved energy supply/demand balance.

Risk factors for operative mortality and morbidity in patients undergoing coronary artery bypass surgery for stable angina pectoris.

Risk factors for a poor early outcome of surgery for stable angina pectoris were evaluated in 2659 consecutive patients from a defined population. The total operative mortality (death within 30 days after surgery) was 2.6% and the frequency of myocardial injury (increase in S-ASAT to greater than 2.0 mu kat l-1 and in S-CKMB to greater than 1.5 mu kat l-1 within 48 h postoperatively or death in the operating room) 14%. Mortality was related to New York Heart Association (NYHA) classification (P less than 0.001), age (less than or greater than 70 years, P = 0.001), duration of symptoms (less than or greater than 8 years, P = 0.001), aortic cross-clamp (ACC) time (P less than 0.001), and cardiopulmonary bypass (CBP) time (P less than 0.001). A multivariate analysis showed that the combination of NYHA class, ACC time and age best predicted operative mortality. Myocardial injury was related to NYHA functional class (P less than 0.001), duration of symptoms (P less than 0.001), regrafting procedure (P less than 0.001), cardiac related dyspnoea (P = 0.015), ACC time (P = 0.001), CPB time (P = 0.001), relative volume of cardioplegic solution (P less than 0.001), and thromboendarterectomy procedure (P = 0.004). The set of variables that best predicted myocardial injury consisted of ACC time, relative volume cardioplegic solution, NYHA class, regrafting procedure and duration of symptoms. However, these risk factors indicated only moderately high risks, and high-risk patients could not be selected with sufficient accuracy.

Early results of aortic valve replacement with or without concomitant coronary artery bypass grafting.

Early results of aortic valve replacement were reviewed in 962 unselected patients, 659 without concomitant coronary bypass surgery (AVR group) and 303 with combined valve replacement and coronary artery bypass grafting (AVR + CABG). The early (less than 30-day) mortality was 4.6% in the AVR, and 5.9% in the AVR + CABG group. Multivariate analysis showed coronary artery stenoses and NYHA functional class to be independent predictors of early mortality in the AVR group, and the number of distal anastomoses as the strongest predictor in AVR + CABG. The incidence of peroperative technical complications in the cases with fatal outcome was 27% in the AVR and 6% in the AVR + CABG group. The incidence of myocardial injury (new Q wave or evidence of increased enzyme leakage) was 11% in AVR and 21% in AVR + CABG. Independent predictors of postoperative myocardial injury were aortic cross-clamp time, year of surgery, coronary artery stenoses and NYHA class in AVR and aortic cross-clamp time and year of surgery in AVR + CABG. The study suggests that coronary artery disease increases risk in aortic valve replacement with or without CABG. Replacement should be undertaken before endstage of the disease (NYHA IV), with CABG if significant coronary disease is present, and in multivessel disease the number of distal anastomoses should be restricted in order to shorten aortic cross-clamp time.

Continuous vectorcardiography in cardiac surgery: natural course of vector changes and relationship to myocardial oxygen uptake.

Continuous vectorcardiography was registered before and during the first 18 hours after cardiac surgery in 53 patients. QRS vector changes (QRS-VD) occurred during the operation, but no further changes were observed postoperatively. The ST vector (ST-VM) increased during the operation, and a further slight increase occurred postoperatively. Perioperative myocardial infarction occurred in three patients. Their ST-VM was higher than the average in patients without myocardial infarction, while QRS-VD did not differ from the average pattern. Twelve other patients were studied in pacemaker-induced moderate tachycardia. QRS-VD increased in proportion to heart-rate changes (rs median = 0.93, p less than 0.01). QRS-VD also correlated with myocardial oxygen uptake (rs median = 0.62, p less than 0.05). The ST-VM responses were not uniform. The data suggest that vectorcardiogram variables can provide information related to myocardial energy metabolism.

Early results of mitral valve replacement.

Early results of mitral valve replacement were reviewed in 336 unselected patients, 261 without and 75 with concomitant coronary artery bypass grafting (MVR and MVR + CABG groups). Early (less than 30 days) mortality was 7% in the MVR and 16% in the MVR + CABG group, with cardiac failure as the dominant cause. In multivariate analysis, the variables most strongly related to early mortality were congestive heart failure, diabetes and previous cardiac surgery in the MVR group and congestive heart failure in MVR + CABG. In the cases with fatal outcome the incidence of peroperative technical complications was 32% at MVR and 17% at MVR + CABG. The incidence of myocardial injury was 21% and 35% in the respective groups, and the early mortality in these cases was 19% vs 23%. Half of all fatal cases showed signs of peroperative myocardial injury. Multivariate analysis showed factors independently related to myocardial injury to be year of surgery and aortic cross-clamp time in MVR and previous cardiac surgery in MVR + CABG. Operation before cardiac reserves are reduced, optimal peroperative myocardial preservation and avoidance of technical errors should improve results of MVR.

Myocardial recovery after cardiac surgery: a study of hemodynamic performance and electrophysiology during the first 18 postoperative hours.

Hemodynamic and vectorcardiographic variables were monitored in 23 patients with acquired heart disease, before and during the first 18 postoperative hours of cardiac surgery. The hemodynamic pattern directly after surgery was characterized by left ventricular depression and increased heart rate. Thus, stroke volume index had decreased from the preoperative 29 +/- 1 to 24 +/- 1 mL/beat/m2, and heart rate had increased from 61 +/- 2 to 94 +/- 4 beats/min. During the following hours a gradual normalization of stroke volume occurred, leading to a cardiac index that was adequate after 8 to 10 hours, judging from the mixed venous oxygen saturation (68% +/- 1%). Fourteen patients had an uneventful postoperative course, with no signs of acute myocardial infarction, and did not require inotropic support. These patients had small but consistent vectorcardiographic changes; the QRS vector difference increased moderately, and the ST vector magnitude also increased. No correlation was found between hemodynamic and vectorcardiographic variables, nor between timing of hemodynamic recovery and vectorcardiographic changes. Patients with a perioperative myocardial infarction had a vectorcardiographic pattern that was compatible with acute myocardial infarction. These patients had markedly elevated ST vector magnitude and QRS vector difference values, which were discernible during the first postoperative hours. The present data suggest that the timing of metabolic and electrophysiological recovery of the heart differ, and a computerized vectorcardiographic system may be of value in the early detection of perioperative myocardial infarction.

Endotoxins in cardiopulmonary bypass.

Endotoxins are biologically active substances derived from the cell wall of degraded gram-negative bacteria. Since sterile water may also contain large amounts of endotoxins, these are easily introduced into the manufacturing processes of technical medical material, such as the extracorporeal components used in cardiopulmonary bypass. In hemodialysis, the presence of endotoxins has been related to untoward effects in patients. Using the limulus amebocyte lysate test, we determined the serum concentration of endotoxin in 42 patients undergoing coronary bypass operations. The values increased during cardiopulmonary bypass, exceeding the normal range of 0 to 20 ng/L in 10 patients with a maximum of 82 ng/L, which probably indicates endotoxin release from the extracorporeal equipment. We found no obvious relation to postoperative morbidity. The endotoxin levels of this study are considerably lower than those reported in two other studies of patients having cardiopulmonary bypass. This might be due to less intraoperative contamination but possibly also to differences in analytic methods.