Cardiomyocyte apoptosis after cardioplegic ischemia: comparison to unprotected regional ischemia-reperfusion.

BACKGROUND: Cardiomyocyte apoptosis might contribute to left ventricular (LV) dysfunction following cardiac surgery. Magnetic resonance imaging is considered the most accurate method of determining LV function. We compared apoptosis (by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, TUNEL, staining and detection of caspase 3 activation) and LV function after regional ischemia-reperfusion (I-R) and global cardioplegic ischemia. METHODS: Pigs were randomized to undergo regional myocardial I-R for 20 + 20 min, global myocardial ischemia with cardiopulmonary bypass (CPB) for 40 min or CPB without ischemia (control), followed by 274 min of reperfusion. RESULTS: Compared with the control group, the number of TUNEL-positive cardiomyocytes was higher in the global ischemia group with CPB (0.024 ± 0.014%; p = 0.02) and further increased in areas of unprotected regional I-R (0.444 ± 0.562%; p = 0.003, vs. control). Myocytes with active caspase 3 were detected after global and regional ischemia. The global ejection fraction did not differ between CPB and regional I-R groups. CONCLUSIONS: The use of cardioplegia and CPB efficiently protects the heart from global I-R-induced cardiomyocyte apoptosis during open heart surgery.

Non-invasive estimation of hepatic glucose uptake from [18F]FDG PET images using tissue-derived input functions.

PURPOSE: The liver is perfused through the portal vein and hepatic artery. Quantification of hepatic glucose uptake (HGU) using PET requires the use of an input function for both the hepatic artery and portal vein. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not practical in humans. The aim of this study was to develop and validate a new technique to obtain quantitative HGU by estimating the input function from PET images. METHODS: Normal pigs (n = 12) were studied with [18F]FDG PET, in which arterial and portal blood time-activity curves (TAC) were determined invasively to serve as reference measurements. The present technique consisted of two characteristics, i.e. using a model input function and simultaneously fitting multiple liver tissue TACs from images by minimizing the residual sum of square between the tissue TACs and fitted curves. The input function was obtained from the parameters determined from the fitting. The HGU values were computed by the estimated and measured input functions and compared between the methods. RESULTS: The estimated input functions were well reproduced. The HGU values, ranging from 0.005 to 0.02 ml/min per ml, were not significantly different between the two methods (r = 0.95, p < 0.001). A Bland-Altman plot demonstrated a small overestimation by the image-derived method with a bias of 0.00052 ml/min per g for HGU. CONCLUSION: The results presented demonstrate that the input function can be estimated directly from the PET image, supporting the fully non-invasive assessment of liver glucose metabolism in human studies.

Non-invasive estimation of hepatic blood perfusion from H2 15O PET images using tissue-derived arterial and portal input functions.

PURPOSE: The liver is perfused through the portal vein and the hepatic artery. When its perfusion is assessed using positron emission tomography (PET) and (15)O-labeled water (H(2) (15)O), calculations require a dual blood input function (DIF), i.e., arterial and portal blood activity curves. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not feasible in humans. The aim of the present study was to develop a new technique to estimate quantitative liver perfusion from H(2) (15)O PET images with a completely non-invasive approach. METHODS: We studied normal pigs (n=14) in which arterial and portal blood tracer concentrations and Doppler ultrasonography flow rates were determined invasively to serve as reference measurements. Our technique consisted of using model DIF to create tissue model function and the latter method to simultaneously fit multiple liver time-activity curves from images. The parameters obtained reproduced the DIF. Simulation studies were performed to examine the magnitude of potential biases in the flow values and to optimize the extraction of multiple tissue curves from the image. RESULTS: The simulation showed that the error associated with assumed parameters was <10%, and the optimal number of tissue curves was between 10 and 20. The estimated DIFs were well reproduced against the measured ones. In addition, the calculated liver perfusion values were not different between the methods and showed a tight correlation (r=0.90). CONCLUSION: In conclusion, our results demonstrate that DIF can be estimated directly from tissue curves obtained through H(2) (15)O PET imaging. This suggests the possibility to enable completely non-invasive technique to assess liver perfusion in patho-physiological studies.

Infective endocarditis in a Finnish teaching hospital: a study on 326 episodes treated during 1980-2004.

OBJECTIVES: To evaluate potential changes of infective endocarditis (IE) in patients treated in a Finnish teaching hospital during the past 25 years. PATIENTS: 326 episodes of IE in 303 patients treated during 1980-2004 were evaluated for clinical characteristics and their changes over time. RESULTS: The mean age of the patients increased with time (from 47.2 to 54.5 years, p = 0.003). Twenty-five (7.7%) episodes were associated with intravenous drug use (IVDU), with a significant increase of these episodes after 1996 (from 0 to 19 (20%), p < 0.001). Viridans streptococci were the most common causative agents of IE during 1980-1994, but after that Staphylococcus aureus was the most common pathogen (p = 0.015). The proportion of IE of the aortic valve decreased during the study (from 30 (49%) to 26 (27%), whereas the proportions of mitral (11 (18%) to 33 (35%) and tricuspid valve IE (0 to 13 (14%) increased correspondingly (p = 0.001). This was mainly due to more patients with IVDU. Chronic dialysis for renal failure as an underlying condition increased over time (from 0 to 7 (7.4%), p = 0.015) but no other predisposing conditions changed. Complications such as neurological manifestations and heart failure did not change in frequency, but the incidence of lung emboli increased (from 0% to 10.5%, p < 0.001); 83% of these emboli occurred in patients with IVDU. The proportion of patients requiring surgical treatment and mortality due to IE did not change. CONCLUSIONS: During these 25 years, the causative agents, affected valves and complications of IE changed to some degree. These changes were mainly attributed to the increase of IVDU-associated IE. Except for the increase in age, the clinical presentation and outcome in non-addicts remained substantially unchanged.

Stimulated expression of cyclooxygenase-2 in porcine heart after bypass circulation and cardioplegic arrest.

OBJECTIVES: Cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes catalyze the initial step in the formation of prostaglandins, which have a role in the regulation of circulation and in inflammatory reactions. As hypoxia is reported to stimulate the expression of COX-2, we have investigated the effects of bypass circulation and cardioplegic arrest on the expression COX-1 and COX-2 in the myocardium of porcine hearts. METHODS: Anaesthetized pigs were connected to cardiopulmonary bypass and the hearts were arrested by cold crystalloid cardioplegia for 30 min and reperfused thereafter for 90 min. Then the mRNA and protein levels of COX-1 and COX-2 were measured from the transmural specimens of the left ventricular myocardium by Northern and Western blot analyses. Reference specimens were from the hearts of unoperated control pigs and from sham-operated pigs, which were connected to cardiopulmonary bypass for 120 min without any aortic clamping. RESULTS: COX-1 mRNA was expressed in unoperated control porcine hearts, whereas the expression of COX-2 mRNA was weak in control hearts. The expression of COX-2 mRNA increased to 170% of the control level in the hearts of sham-operated pigs and to 180% in arrested hearts, while the level of COX-1 mRNA was not changed. Both COX-1 and COX-2 proteins were detected by Western blot analysis in the myocardial specimens of control hearts. After cardioplegic arrest, the level of COX-2 protein increased to 280% of the control level in arrested hearts, whereas the level of COX-1 protein remained unchanged. CONCLUSIONS: These results indicate that the expression of the COX-2 gene is stimulated in the ventricular myocardium of the porcine heart after bypass circulation and cardioplegic arrest.

Adenosine in myocardial protection given through three windows of opportunity. An experimental study with pigs.

OBJECTIVE: Adenosine (ADO) has been shown to have beneficial effects against tissue injury after myocardial ischemia. However, the timing and dose of ADO administration have not been defined. This study was designed to determine the cardioprotective effect of exogenous ADO in an experimental open heart surgery model in pigs. DESIGN: The animals were openly divided into two groups both undergoing 30 min of total cardiac arrest. In the control group animals received cold crystalloid cardioplegic solution. In the ADO group ADO was added to cardioplegic solution and in addition ADO was infused to the superior vena cava for 2 h starting 30 min before cardiac arrest. The pumping function of the heart was measured with echocardiography and myocardial blood flow was measured with microspheres and positron emission tomography (PET). Cardiomyocyte apoptosis was detected and tumor necrosis factor (TNF) levels were measured. RESULTS: Better post-ischemic pumping function was found in the ADO group (relative decrease 43.7% vs 55.4%, p = 0.20 between the groups). The cardiac output decreased significantly from the baseline values (p < 0.05 in both groups). There was a temporary decrease in myocardial blood flow post-ischemically, followed by a compensatory increase during the later reperfusion period. The cardiomyocyte apoptosis was induced significantly in both groups. CONCLUSIONS: In this experiment two important details were noticed. Firstly, cardiomyocyte apoptosis is involved in ischemia-reperfusion injury associated with open heart surgery. Secondly, PET is a comparable method with the microsphere technique when coronary flow is studied. No significant effects of ADO against ischemia-reperfusion injury could be shown. However, there were some signsof positive outcome, even though statistical significance could not be reached.

In vivo detection of vascular adhesion protein-1 in experimental inflammation.

Vascular adhesion protein-1 (VAP-1) is an inflammation-inducible endothelial glycoprotein which mediates leukocyte-endothelial cell interactions. To study the pathogenetic significance of VAP-1 in inflammatory disorders, an in vivo immunodetection method was used to detect the regulation of luminally expressed VAP-1 in experimental skin and joint inflammation in the pig and dog. Moreover, VAP-1 was studied as a potential target to localize inflammation by radioimmunoscintigraphy. Up-regulation of VAP-1 in experimental dermatitis and arthritis could be visualized by specifically targeted immunoscintigraphy. Moreover, the translocation of VAP-1 to the functional position on the endothelial surface was only seen in inflamed tissues. These results suggest that VAP-1 is both an optimal candidate for anti-adhesive therapy and a potential target molecule for imaging inflammation.

Serial measurements of interleukin-6, interleukin-8, tumor necrosis factor-alpha, and soluble vascular cell adhesion molecule-1 in the peripheral blood plasma of human cardiac allograft recipients.

BACKGROUND: Cardiac allograft rejection is largely an inflammatory response that, if allowed to proceed unchecked, will result in hemodynamic compromise or cardiogenic shock. Soluble mediators produced during an inflammatory response could potentially provide information regarding the initiation, progression, and outcome of a rejection episode. To test this hypothesis, we investigated the use of plasma cytokine measurements for interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF alpha) in combination with measurements of soluble vascular cell adhesion molecule-1 (VCAM-1), an adhesion molecule, as a means for the detection of cardiac allograft rejection. METHODS: Serial enzyme-linked immunosorbent assays were performed on plasma samples collected from 29 patients three times per week during the first 8 weeks after transplantation. RESULTS: IL-6 plasma concentrations increased fivefold in the first week after transplantation (p < 0.001 vs pretransplantation levels) and thereafter remained at low levels for the next 6 weeks, with a small increase during the 8 weeks after transplantation (p = 0.006). In contrast, TNF-alpha, IL-8, and VCAM-1 levels remained low during the first 6 weeks after transplantation followed by a rise in mean VCAM-1 levels from 841 +/- 38 to 979 +/- 52 ng/ml at week 8. To determine the relationship of levels of each of the four soluble factors with rejection, the mean values obtained during the time interval 1 to 5 days before rejection were compared to mean values obtained during rejection and at other periods of no rejection (baseline). Cytokine levels were not predictive of rejection (no difference in levels 0 to 5 days before rejection versus baseline, p > 0.3 for IL-6, IL-8, TNF-alpha). However, VCAM-1 levels increased 0 to 5 days before rejection compared with baseline (914 +/- 40 vs 844 +/- 30 ng/ml, p = 0.06). CONCLUSIONS: IL-6 levels are increased immediately after heart transplantation. Circulating IL-6, IL-8, and TNF alpha levels do not predict rejection during the first 8 weeks after transplantation. Soluble VCAM-1 increases within 5 days before rejection and may potentially serve as a noninvasive marker for early rejection.

Acute dissection of ascending aortic aneurysm in a patient with previous coronary artery bypass grafting.

Six years after coronary artery bypass grafting, a 61-year-old man underwent emergency surgery for annulo-aortic ectasia and acute dissection. The aneurysmal tissue and aortic valve were excised and reconstruction was achieved with a composite graft. The patent vein grafts were attached to the composite graft and the original coronary orifices were closed.

MR imaging in the presence of small circular metallic implants. Assessment of thermal injuries.

PURPOSE: The thermal effects of MR imaging in the presence of circular nonferro-magnetic metallic implants were studied in 6 rabbits. MATERIAL AND METHODS: A sternotomy was performed and fixed with stainless steel wires, and small titanium rings (diameter 3 mm) were placed on the surface of the ascending aorta and subcutaneous tissue of the thigh. Four of the rabbits were exposed to an imaging procedure with a 1.5 T scanner applying a T1-weighted spin-echo sequence and a gradient echo sequence. Two of the animals served as unexposed controls. Thirty-six hours after the exposure, tissues adjacent to the implants were examined histologically and compared with corresponding samples of the control animals. RESULTS: In the area of the titanium rings, histologic analysis revealed slight inflammatory changes apparently caused by the operation. No evidence of thermal injury was found, suggesting that the presence of the rings does not contraindicate MR examinations. Necrosis was noted in all of the sternal specimens. This was probably post-operative, but it impaired the assessment of thermal injury in this area.

Semiquantitative measurement of cytokine messenger RNA in endomyocardium and peripheral blood mononuclear cells from human heart transplant recipients.

BACKGROUND: Cytokines play a central role in inflammatory responses and in specific immune responses directed toward alloantigens. The pattern and quantity of cytokines produced in graft rejection can yield valuable information regarding the cellular and molecular mechanisms of the antigraft response. METHODS: We used the polymerase chain reaction to semiquantitatively measure changes in the amount of messenger RNA from the interleukin-1 beta, interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumor necrosis factor-alpha, interferon-gamma, interleukin-1 receptor antagonist, and the interleukin-2 receptor genes in the peripheral blood and endomyocardium of cardiac allograft recipients during the first 8 weeks after transplantation. A total of 328 samples of resting (n = 251) and stimulated (n = 77, stimulated with phytohemagglutinin and lipopolysaccharide for 18 hours) peripheral blood mononuclear cells collected from 16 patients were measured. To measure intragraft cytokine levels, we analyzed 150 endomyocardial biopsy specimens from 19 patients. RESULTS: No elevation in expression was seen before injection, but, after the onset of rejection and concomitant with treatment, there was a decrease in detectable mRNA (p < 0.05) for the pro-inflammatory monokines interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha in resting peripheral blood mononuclear cells, and a decrease for the T-cell derived cytokines interleukin-4 and interleukin-10 in stimulated peripheral blood mononuclear cells. These changes in mRNA expression occurred coincidentally with decreases in the percentage of lymphocytes and monocytes in the peripheral blood after administration of rejection therapy. In endomyocardial biopsy specimens, there were no detectable changes in the quantities of cytokine mRNA specimens for the interferon-gamma, interleukin-6, interleukin-10, interleukin-1ra, and interleukin-1 beta genes before rejection. In general, the levels of these cytokines were near the lower limits of detection by our assay in endomyocardial biopsies, mRNA from the interleukin-2, interleukin-4, tumor necrosis factor-alpha, and interleukin-2R genes were undetectable. CONCLUSIONS: We conclude that changes in the expression of cytokine mRNA in both peripheral blood mononuclear cells and endomyocardial biopsy specimens as measured by the semiquantitative polymerase chain reaction method used in this study does not effectively predict rejection. The decline in peripheral blood mononuclear cell cytokine mRNA after rejection treatment is likely due to changes in the proportion of lymphocytes and monocytes in the peripheral blood in concert with a steroid-induced downregulation by cytokine gene transcription.

Composite graft in annulo-aortic ectasia. Nineteen years' experience without graft inclusion.

OBJECTIVE: The original Bentall procedure for the surgery of annulo-aortic ectasia (AAE) includes the risk of leakage and pseudo-aneurysm formation in the coronary anastomosis. To avoid the complications mentioned above we have used the open technique without the graft inclusion. In this study we evaluate our early and late results. MATERIAL AND METHODS: One hundred consecutive patients with annuloaortic ectasia underwent surgical repair with composite graft between December 1975 and February 1994. In all cases the aneurysmal tissue was radically resected and the origins of the coronary arteries were directly reimplanted to the tube prosthesis. No wrapping was used. Twenty-two patients met the clinical criteria of Marfan syndrome. Thirteen of the patients underwent an emergency operation, because of a rupture of aneurysm in 2 cases and an acute dissection in 11 cases. Additional procedures were performed in 16 patients: mitral valve replacement in 2, coronary artery bypass grafting in 12 patients and in 2 cases the tube prosthesis included aortic arch, too. RESULTS: The overall hospital mortality was 3.0% (3/100). In the elective group there was one hospital death (1/87; 1.1%). In the emergency group two patients died in the operation room (2/13; 16.7%). There have been 13 late deaths among the 97 hospital survivors (13.4%). Four of the late deaths were surgery related. Routine control angiography was performed in all patients 6 months after surgery. Sixty patients who had lived at least 3 years after surgery were called to reangiography and 53 of them came. No pseudo-aneurysm or leakage at distal anastomosis or coronary anastomosis could be seen. A slight dilatation of one or both coronary origins was observed on 15 patients; 9 of whom had Marfan syndrome. CONCLUSIONS: The open technique is simple and can be used in all anatomical variations of the annulo-aortic ectasia. The early and late results are at least comparable with those achieved by other techniques.

Effects of dexmedetomidine on coronary hemodynamics and myocardial oxygen balance.

OBJECTIVE: alpha 2-adrenergic agonists decrease central sympathetic outflow and maintain normal transmural myocardial blood flow distribution, but intravenous bolus doses of these agents can also induce excessive coronary vasoconstriction and myocardial ischemia. The hypothesis of the present study was that a rapid intravenous bolus of dexmedetomidine, a specific alpha 2-adrenergic agonist, will cause coronary vasoconstriction and accompanying myocardial ischemia in young pigs. DESIGN: Prospective, controlled study on experimental animals. SETTING: Animal laboratory of a university cardiorespiratory research center. PARTICIPANTS: Twelve domestic 8-week-old open-chest pigs, anesthetized with high-dose fentanyl. Another six pigs served as controls. INTERVENTIONS: Sequential intravenous dexmedetomidine boluses of 3, 10, and 30 mg/kg were administered, and responses were measured during peak changes (2 minutes after injection) and during recovery after each dose. MEASUREMENTS AND MAIN RESULTS: Left anterior descending coronary artery blood flow, calculated regional coronary vascular resistance, myocardial extraction of oxygen and lactate, plasma catecholamine levels, and conventional central hemodynamic parameters were measured. The two higher doses of dexmedetomidine induced 21% and 29% immediate increases in left anterior descending coronary artery blood flow. At the same time mean systemic blood pressure and pulmonary capillary wedge pressure increased, and calculated regional coronary vascular resistance increased. Myocardial extraction of oxygen and lactate remained unchanged. CONCLUSIONS: Large intravenous doses of dexmedetomidine caused moderate regional coronary vasoconstriction without metabolic signs of myocardial ischemia in young domestic pigs at the same time as a marked vasoconstrictive response in the systemic circulation.

Cardiac transplant coronary artery disease. A multivariable analysis of pretransplantation risk factors for disease development and morbid events.

Coronary artery disease after cardiac transplantation is a major obstacle to long-term survival. The development and progression of coronary artery disease after cardiac transplantation was analyzed in 217 consecutive patients undergoing transplantation. The actuarial freedom from any coronary artery disease (by angiography or autopsy) was 81% at 2 years and 20% at 8 years after transplantation. Coronary artery disease was more prevalent in male than female patients (30% versus 50% free of coronary artery disease at 5 years, p = 0.01). By multivariable analysis, pretransplantation risk factors identified for coronary artery disease included pretransplantation positive cytomegalovirus serologic status of the recipient (p = 0.002) and older donor age (p = 0.07). Progression of coronary artery disease was variable in both time of onset and rate. Earlier detection did not result in more rapid progression. Coronary events severe enough for retransplantation (n = 8) and/or death from coronary artery disease (n = 9) occurred in 15 patients, of whom four underwent retransplantation. The actuarial freedom from coronary events was 88% at 5 years and 79% at 8 years. By multivariable analysis, only male recipient (p = 0.05) was a risk factor for coronary events. Seven of the 15 patients (47%) with coronary events died suddenly of coronary artery disease without prior angiographic evidence of severe coronary disease. Coronary artery disease is progressive. Improved surveillance methods are required to detect the disease and institute timely intervention to prevent the occurrence of unanticipated death.

Results of cardiovascular surgery in the Marfan syndrome. A retrospective study of 49 patients.

To evaluate the outcome of cardiovascular surgery in the Marfan syndrome, the records of 49 patients (median age 35 years) who underwent 60 operations were reviewed. Primary surgery was elective in 39 patients and emergency in ten. Non-dissecting aneurysm with diameter 4-19 cm was present in 34 cases and distal, isolated aneurysm in four. In eight cases there was type A acute aortic dissection with median diameter 5.0 cm. One patient was operated on for mitral valve insufficiency, one for ventricular septal defect and one (acute) for endocarditis. Composite grafts were used for aortic root reconstruction. Operative complications occurred in 24% of the patients. The 30-day survival was 92%. There were five (10%) late deaths. Survival after a median of 8 years postoperatively was 82%. The early and late results of cardiovascular surgery in the Marfan syndrome thus are concluded to be generally favourable. As late reoperation frequently is needed, however, close monitoring is advocated even after successful primary surgery.

Myocardial reperfusion after coronary bypass surgery. Suture of only distal or all anastomoses with the aorta cross-clamped?

Sixty patients undergoing elective coronary artery bypass grafting were randomly allocated into two groups, each of 30 patients and similar as regards age, sex, number of coronary artery bypasses and left ventricular ejection fraction. In group A the proximal anastomoses of vein grafts were sutured after aortic declamping during partial occlusion of the aorta, and in group B these anastomoses were done during aortic cross-clamping. The aortic cross-clamp time was significantly longer in group B than in group A (72 vs 57 min, p < 0.0001). Myocardial cooling and rewarming and the number of sustained or possible perioperative myocardial infarctions were equal in both groups. Central haemodynamics showed no intergroup difference, before or after induction of anaesthesia or at the end of surgery. Conduction disturbances were more common in group A than in group B (12 vs 3, p = 0.0246), and transient external pacing was more often required in group A (9 vs 2, p = 0.0534). Myocardial reperfusion via native coronary arteries and bypass grafts gives better protection against conduction disturbances than does reperfusion via only native arteries, despite longer aortic cross-clamping time.

Myocardial viability: fluorine-18-deoxyglucose positron emission tomography in prediction of wall motion recovery after revascularization.

To assess the value of positron emission tomography (PET) imaging with fluorine-18-deoxyglucose ([18F]FDG) in predicting cardiac wall motion recovery after revascularization, 48 consecutive patients with previous myocardial infarction were studied. The normalized [18F]FDG uptake at rest was assessed semiquantitatively and compared to perfusion at rest as studied by SPECT imaging. Wall motion was analyzed with echocardiography before and after revascularization. Wall motion recovery occurred in 27 (30%) of the revascularized 90 dysfunctional segments. Preserved [18F]FDG uptake (mean +/- 2 SD) was commonly found in dysfunctional segments, but only 54% of these segments recovered after revascularization. Subnormal [18F]FDG uptake identified accurately the segments with no potential to recover (predictive value 100%). By using an optimized threshold value for normalized [18F]FDG uptake, the sensitivity of 85% and specificity of 84% to predict functional recovery were reached simultaneously. However, in the segments with moderately or severely reduced perfusion at rest, the diagnostic accuracy of [18F]FDG uptake for viability was 100%. The results of this study show that the presence of viable tissue indicated by preserved [18F]FDG uptake does not inevitably imply functional recovery after revascularization. However, acceptable diagnostic accuracy for viability might be reached by [18F]FDG alone, providing that appropriate uptake limits are used. The combined evaluation of [18F]FDG uptake and perfusion enables precise assessment of myocardial viability.

Combined cardioplegia delivery offers no advantage over antegrade cardioplegia administration in coronary surgical patients with a preserved left ventricular function.

The effects of antegrade and of combined antegrade and retrograde cardioplegia were compared in 101 patients undergoing elective coronary artery surgery. The patients were randomly allocated to two groups: antegrade cardioplegia was administered in 53 patients and combined cardioplegia in 43 patients. The patients of the two groups were similar in age, sex and left ventricular ejection fraction. Aortic clamping time and the number of coronary bypasses were equal in the groups. The ventricular septal temperature was measured continuously during cardioplegia administration, after each distal anastomosis accomplished, and continuously after aortic declamping. Serum CK-MB activities were serially measured for up to 3 days postoperatively. Electrocardiograms (ECG) were taken preoperatively, as well as on the first, second and eighth postoperative days. The left ventricular function was evaluated with a volume load test preoperatively and on the first postoperative morning. The two groups were similar with respect to myocardial cooling, response to volume loading, the number of patients with perioperative myocardial infarctions, cardiac arrhythmias or atrioventricular conduction blocks and clinical outcome. However, the CK-MB activities were lower in the antegrade group suggesting better myocardial protection in an unselected group of patients undergoing coronary artery bypass grafting.

Prediction of wound tensile strength: an experimental study.

Wound cell specimens were obtained using a Cellstic device after 24, 48 and 72 h healing time in guinea-pig skin wounds. Cell counts from these were compared with the tensile strength values of the same wounds 7, 14 or 21 days after operation. No single cell type was predictive of wound tensile strength, although absolute numbers of different cells and selected ratios of cell types on the second or third day after operation were more predictive. Absolute and proportional changes from day 1 to day 2 had the greatest predictive power with a mean error of 9.46 per cent (F = 13.6, P less than 0.0001). The same regression model was predictive in animals with lower wound tensile strengths given perioperative hydrocortisone (3 mg/100 g).

Operative fixation of fractures of the thoracic and lumbar vertebrae by Williams plates with reference to late kyphosis.

Thirty patients with fractures of the thoracic and lumbar spine, treated by the Williams plating technique (with or without fusion) between 1966 and 1978, were reviewed and followed up for an average of 6.5 years (range 2-14 years). The average degree of primary traumatic kyphosis was 11.4 degrees (range 0-33 degrees), and the average degree of late deformation kyphosis during follow-up was 17.4 degrees (range 0-30 degrees). The average loss of operative correction during follow-up was 9.8 degrees. Technical late complications, such as loosening of screws, occurred in half of the patients, but they did not affect the degree of spinal deformation. The corrective result, with reference to late deformity (kyphosis), largely correlated with the degree of primary traumatic kyphotic deformation and the severity of the neurologic lesion. The best late correction result was achieved with moderate primary kyphosis in patients with bursting fractures. Spinal fusion tended to give better results, especially in anterior wedge fractures, in maintenance of the correction of kyphosis, while laminectomy tended to give poorer results. None of the 15 patients with primary complete paraplegia showed improvement, while 80 per cent of patients with incomplete paraplegia made a moderate recovery.