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Purpose: The optimal volume and dose of corticosteroid injections for treatment of carpal tunnel syndrome (CTS) have not yet been established. It is unknown whether the volume of injectate influences the outcome of carpal tunnel injection. The purpose of this study was to assess whether there is an association between the volume of injectate and subsequent intervention in the treatment of CTS., Methods: This study evaluated residents of Olmsted County, MN, who were treated with a corticosteroid injection for CTS between 2001 and 2010. Failure of treatment was the primary outcome, defined as a subsequent intervention: either a second injection or carpal tunnel release within 1 year of initial injection. General estimating equations logistic regression was used to assess the association between injectate volume and rate of treatment failure, adjusting for age, sex, effective dose of steroid, type of steroid injected, electrodiagnostic severity, and the presence of comorbidities such as rheumatoid arthritis, diabetes mellitus, peripheral neuropathy, and radiculopathy., Results: There were 856 affected hands in 651 patients. A total of 56% (n = 484) of treated hands received subsequent treatment within 1 year. Multivariable analysis showed that a larger injectate volume was significantly associated with reduced rate of treatment failure within 1 year. Rheumatoid arthritis and ultrasound-guided procedures were also associated with a reduced rate of treatment failure, whereas severe electrodiagnostic results were associated with an increased rate of failure., Conclusions: This study showed that a larger volume of corticosteroid injection is associated with reduced odds of subsequent intervention after a single corticosteroid injection in CTS. Further research is needed to determine the optimal volume for steroid injections in the treatment of CTS., Type of Study/level of Evidence: Prognostic IV., (Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

Left internal mammary artery to left anterior descending coronary artery bypass grafting integrated with percutaneous coronary angioplasty (hybrid procedure) offers multivessel revascularization with minimal morbidity in high-risk patients. This is caused in part by the avoidance of cardiopulmonary bypass-related morbidity and manipulation of the aorta coupled with minimally invasive techniques. Hybrid revascularization is currently reserved for particularly high-risk patients or those with favorable anatomic variants however, largely because of the emergence of off-pump coronary artery bypass grafting, which permits more complete multivessel revascularization, with low morbidity in high-risk groups. The wider introduction of hybrid revascularization is limited chiefly by the high number of repeat interventions compared with off-pump coronary artery bypass grafting, which occurs because of the target vessel failure rate of percutaneous coronary intervention. Other demerits are the costs and logistic problems associated with performing two procedures with differing periprocedural management protocols. Recently, drug-eluting stents have reduced the need for repeat intervention after percutaneous coronary intervention, and this has raised the possibility that the results of hybrid revascularization may now equal or even better those of off-pump coronary artery bypass grafting. Although undoubtedly effective at reducing in-stent restenosis, drug-eluting stents will not address the issues of incomplete revascularization or the logistic problems associated with hybrid. Uncertainty regarding the long-term effectiveness of drug-eluting stents in many patients, as well as their high cost when compared with those of off-pump coronary artery bypass grafting surgery, also militates against the wider introduction of hybrid revascularization.

Background: Intermittent antegrade cold blood cardioplegia is superior to warm blood cardioplegia in patients who have aortic valve operation. This study compared the cardioprotective efficacy of intermittent antegrade and retrograde cold blood cardioplegia with emphasis on metabolic stress in the left and right ventricles., Methods: Thirty-nine patients who had elective aortic valve replacement were prospectively randomly selected to receive intermittent antegrade or retrograde cold blood cardioplegia. Left and right ventricular biopsies were collected 5 minutes after institution of cardiopulmonary bypass and 20 minutes after cross-clamp removal and were used to determine metabolic changes. Metabolites (adenine nucleotides, amino acids, and lactate) were measured using high-powered liquid chromatography and enzymatic techniques. Serial measurement of troponin I release was also used as a marker of myocardial injury., Results: Preoperative characteristics were similar between groups. There was no in-hospital mortality, and no differences were observed in postoperative complications. Preischemic concentration of taurine was significantly higher in left ventricular biopsies, whereas adenosine triphosphate tended to be lower in the left ventricle. At reperfusion adenosine triphosphate levels were significantly lower than preischemic levels in right but not left ventricles irrespective of the route of delivery. The alanine-glutamate ratio was significantly elevated in both ventricles. Myocardial injury as assessed by troponin I release was also significantly increased in both groups., Conclusions: Retrograde and antegrade intermittent cold blood cardioplegic techniques are associated with suboptimal myocardial protection. Metabolic stress was more pronounced in the right than the left ventricle irrespective of the cardioplegic route of delivery used.

Background: This study analyses the development of off-pump coronary artery bypass (OPCAB) surgery training at a single institution, and compares the early and midterm clinical outcomes of OPCAB and conventional coronary artery bypass grafting (CABG) procedures performed by trainees with or without direct consultant cardiothoracic surgeon supervision., Methods: Analysis was undertaken on data prospectively recorded on a computer database (Patient Analysis and Tracking System). Of the 2,422 CABG operations performed between January 1999 and December 2001, 969 (40%) were carried out by trainees either off pump (422) or on pump (547)., Results: Although the total number of CABG operations performed by trainees remained constant, there was a significant increase in the number of OPCAB operations during the study period compared with conventional CABG, as well as an increase in the average number of grafts per patient in the OPCAB group (both p < 0.05). Furthermore, a significant trend towards using two or more arterial conduits in the OPCAB group was observed in the study period. The number of OPCAB operations performed by trainees as independent operators without direct consultant supervision also increased significantly (p < 0.05). Early and midterm clinical outcomes were similar between patients operated by trainees on pump or off pump as independent operators versus under direct consultant supervision., Conclusions: The significant increase in OPCAB operations performed by trainees as independent operators or under direct consultant supervision, as well as the increase in the number of grafts per patient and arterial conduits used for myocardial revascularization, demonstrate a progression of training in beating heart surgery for cardiothoracic trainees. Improvements in the techniques have made it safe to teach trainees off-pump multivessel coronary artery revascularization.

Background: Although there is growing evidence to suggest that the administration of magnesium (Mg2+) to patients undergoing coronary artery bypass grafting (CABG) and to patients after myocardial infarction is beneficial, the addition of Mg2+ to cardioplegic solutions remains controversial. The aim of this study was to compare the effects of intermittent warm blood cardioplegia with and without Mg2+ supplementation on the early postoperative clinical outcomes in patients undergoing both elective or urgent CABG., Methods: Four hundred patients undergoing CABG were prospectively randomized to receive either blood cardioplegia without Mg2+ (BC, n = 200) or supplemented with Mg2+ (BC-Mg2+, n = 200). Serial plasma Mg2+ concentrations were recorded at base line and postoperatively from days 1 to 4., Results: Patient characteristics were similar and no significant differences were found in early mortality and morbidity in the two groups. Analysis of 178 patients undergoing urgent CABG for unstable symptoms (BC = 95, BC-Mg2+ = 83) demonstrated a significantly lower requirement for internal defibrillation and temporary epicardial pacing in the BC-Mg2+ group. Furthermore, there was a nearly twofold lower incidence of new postoperative atrial fibrillation in the BC-Mg2+ group compared with the BC group (19% versus 34%, p = 0.03). Postoperative plasma Mg2+ levels were consistently lower in those patients who developed new postoperative atrial fibrillation compared with those who did not (p = 0.05)., Conclusions: The addition of Mg2+ to warm blood cardioplegia resulted in a lower incidence of intraoperative and postoperative arrhythmias in patients undergoing urgent CABG for unstable angina.

Long-term survival, relief of angina, and prevention of myocardial infarction after coronary revascularization are related to the preoperative status of the patient, progression of coronary artery atherosclerosis, and the patency of the conduits used. The increased use of the internal mammary artery for coronary grafting depends upon the accumulation of data on superior late patency compared with venous conduits. These data have supported the simultaneous use of both left and right internal mammary arteries with reported improved late survival. However, controversy still surrounds the clinical and angiographic outcomes of some of the surgical strategies of bilateral internal mammary artery grafting. This review examines a range of surgical strategies of bilateral internal mammary artery grafting and their mid- and long-term clinical and angiographic outcomes. From the available data, careful preoperative selection of patients is paramount. Clinical and angiographic outcome of bilateral internal mammary grafting is superior to single internal mammary grafting with supplemental vein grafts when pedicled, sequential, or free aorto-coronary internal mammary artery is used. Further studies are needed to evaluate the midterm and long-term clinical and angiographic outcomes of complex strategies such as Y or T procedures.

Background: Small-sized mechanical aortic prostheses are commonly associated with generation of high transvalvular gradients, particularly in patients with large body surface area, and can result in patient-prosthesis mismatch. This study evaluates the hemodynamic performance of 21-mm Sorin Bicarbon bileaflet mechanical prostheses using dobutamine stress echocardiography., Methods: Fourteen patients (7 women; mean age, 63+/-8 years) who had undergone aortic valve replacement with a 21-mm Sorin Bicarbon bileaflet mechanical prosthesis 32.4+/-5.1 months previously were studied. After a resting Doppler echocardiogram, a dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 30 microg x kg(-1) x min(-1) at 15-minute intervals. Pulsed- and continuous-wave Doppler echocardiographic studies were performed at rest and at the end of each increment of dobutamine. Both peak and mean velocity and pressure gradient across the prostheses were measured, and effective orifice area, discharge coefficient, and performance index were calculated., Results: Dobutamine stress increased heart rate and cardiac output by 83% and 81%, respectively (both p < 0.0001), and mean transvalvular gradient increased from 15.6+/-5.5 mm Hg at rest to 35.4+/-11.9 mm Hg at maximum stress (p < 0.0001). Although the indexed effective orifice area was significantly lower in patients with a larger body surface area, this was not associated with any significant pressure gradient. The performance index of this valve was unchanged throughout the study. Regression analyses demonstrated that the mean transvalvular gradient at maximum stress was independent of all variables except resting gradient (p = 0.05). Body surface area had no association with the changes in cardiac output, transvalvular gradient at maximum stress, and effective orifice area., Conclusions: These data show that the 21-mm Sorin Bicarbon bileaflet mechanical prosthesis offers an excellent hemodynamic performance with full utilization of its available orifice when implanted in the aortic position. The lack of significant transvalvular gradient in patients with a larger body surface area suggests that patient-prosthesis mismatch is highly unlikely when this prosthesis is used.

Background: Concern has been raised about residual significant gradients when small aortic prostheses are used, particularly in patients with large body surface areas. We studied the performance of six types of small aortic prostheses using dobutamine stress echocardiography., Methods: Sixty-three patients (mean age, 67 +/- 7 years) who had undergone aortic valve replacement 17 +/- 6 months previously were studied. Two bileaflet mechanical prostheses (St. Jude Medical and CarboMedics: sizes, 19 mm and 21 mm) and two biological prostheses (Medtronic Intact and St. Jude BioImplant: size, 21 mm) were evaluated. A graded infusion of dobutamine was given and Doppler studies of valve performance were carried out., Results: All prostheses except one biological valve had acceptable hemodynamic performance under stress. Using regression modeling, gradient at rest was the only variable found to predict gradient under stress (p < 0.001). Moreover, the most important predictor of gradient at rest was valve design, which accounted for 72% of the variance (p < 0.001). This relationship was independent of valve size (19 mm or 21 mm) or material (ie, mechanical or biological). Body surface area accounted for 4% of the variance in gradient only., Conclusions: The main predictor of transprosthetic gradient is the inherent characteristics of each particular prosthesis, with relatively insignificant contribution from variations in body surface area. Patient-prosthesis mismatch is not a problem of clinical significance when certain modern valve prostheses are used.

Proliferation of vascular smooth muscle cells (VSMC) is a principal event in neointima formation in saphenous vein-coronary artery bypass grafts. Since endothelin-1 (ET-1) promotes VSMC replication and ET-1 receptor antagonists inhibit neointima formation in arterial injury models, it is reasonable to propose that ET-1 may be involved in neointima formation in vein grafts. However, it is not known what alterations of ET-1 and its receptors (if any) occur in vein grafts. The objective of this study, therefore, was to investigate the distribution of ET-1 and ET-1 receptor subtypes (ET(A) and ET(B)) in porcine vein grafts. Unilateral interposition saphenous vein grafting was performed by end to end anastomosis after excision of a segment of carotid artery in Landrace pigs. One month after surgery, vein grafts, ungrafted saphenous veins and carotid arteries were excised, ET-1 immunoreactivity identified by immunocytochemistry and ET(A) and ET(B) receptor subtypes studied using autoradiography. In vein grafts, there was a greater density of ET(A) compared to ET(B) receptors in both the tunica media and neointima. ET(A) binding in the tunica media of ungrafted saphenous vein was greater than that in the carotid artery or vein grafts, but greater in the vein graft compared to the carotid artery. Immunoreactive ET-1 was located in endothelial cells and throughout the neointima of the vein graft. Dense ET-1 binding (to both ET(A) and ET(B) receptors) was also associated with microvessels in the adventitia within the graft. In vein grafts, there was strong ET(B) binding to neutrophils which were present in high numbers at the subendothelium and within the adventitia. It is concluded ET(A) receptors may play a role in vein graft thickening at the medial and neointimal VSMC level, whereas ET(B) receptors may play a role in microangiogenesis. The higher levels of ET(A) receptors in the tunica media of ungrafted saphenous vein relative to the carotid artery and vein graft may also render this conduit susceptible to neointima formation. These data indicate that studies on the effect of ET receptor antagonists on the pathobiology of vein graft disease is warranted.

Improved outcome after coronary bypass surgery over the last decade has been attributed largely to the increasing use of arterial conduits and their superior patency rates over that of saphenous vein grafts. In spite of this trend, autologous saphenous vein has remained an important and convenient conduit for a variety of operative scenarios, and is still used for more than 70% of grafts. As a result, vein graft failure continues to represent a significant clinical and economic burden upon the health care service. Between 15 to 30% of saphenous vein grafts occlude within the first year of surgery, increasing to over 50% after 10 years. By this time, more than 10% of patients will require further intervention to alleviate symptoms arising from occluded grafts and progression of native disease. Graft occlusion arises either from early thrombosis or the later onset of 'vein graft disease' and subsequent atherosclerotic changes.

Left ventricular volume reduction has recently been introduced as a surgical treatment for end stage dilated cardiomyopathy. This operation involves the resection of a slice of viable left ventricular myocardium in order to reduce the wall tension imposed upon the contracting heart chamber. Early results are encouraging, but clinical evaluation on a larger scale is required. In the present article, we describe the indications, surgical principles and results of left ventricular volume reduction surgery with reference to our group's experience.

Objective: Minimally invasive direct coronary artery bypass (MIDCAB) using the left internal mammary artery (IMA) to the left anterior descending (LAD) coronary artery can be performed with low operative risk. MIDCAB can be combined with percutaneous transluminal coronary angioplasty (PTCA) to treat patients with multivessel disease. We report here our experience with staged MIDCAB and PTCA in the management of a selected group of patients., Methods and Results: 11 patients (9 males, mean age 64.6+/-8.7 years) with multivessel coronary artery disease received left IMA grafts to the LAD using the MIDCAB approach. There were no postoperative morbidity or mortality. All patients were extubated within 4 h of leaving the operating room with a mean ITU stay of 12.8 h. All patients but two underwent coronary angioplasty during the same hospital admission, 3.8+/-1.3 days after the MIDCAB procedure. Angiography confirmed IMA grafts patency in all patients, and complete revascularisation by PTCA of other coronary arteries was possible in all patients but one. Mean hospital stay was 5.9 days, and all patients remain free of angina at a mean follow-up period of 11.4 months., Conclusions: Staged MIDCAB and angioplasty is an experimental approach for the management of selected patients with multi-vessel coronary artery disease. Further experience is needed to clarify patient selection and the long-term outcome of this approach.

Background: High residual transvalvular gradients have been reported with the use of small Medtronic Intact aortic valve prostheses. The aim of this study was to evaluate the hemodynamic performance of 21-mm prostheses using dobutamine Doppler echocardiography., Methods: Ten patients (7 women; mean age, 79 years) who had undergone aortic valve replacement with 21-mm Medtronic Intact prostheses 19.1 +/- 9.9 (standard deviation) months previously were studied. Dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 10 and 20 microg x kg(-1) x min(-1) at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of each valve were calculated, and peak and mean velocity and pressure drop across the prostheses were measured. Cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract., Results: Dobutamine stress increased heart rate and cardiac output by 68% and 65%, respectively (both p < 0.005), and mean transvalvular gradient increased from 19.1 +/- 5.1 mm Hg at rest to 33.2 +/- 7.7 mm Hg at maximum stress (p < 0.0001). Regression analyses demonstrated that maximum-stress gradient was independent of all variables except resting gradients (p < 0.004). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress., Conclusions: These data show that the 21-mm Medtronic Intact aortic prosthesis exhibits acceptable hemodynamic performance. Transvalvular gradients remained within a clinically acceptable range, both at rest and at maximum stress. Moreover, overall hemodynamic performance suggests that patient-prosthesis mismatch is unlikely to be a problem of clinical importance when this prosthesis is used.

The evaluation of myocardial damage in relation to cardiac operation from a clinical and a research perspective is of great importance, particularly for the evaluation of different cardioprotective strategies. Although measurements of serum biochemical markers have often been used, their value has been limited by their lack of sensitivity and specificity in the presence of skeletal muscle damage. A newer range of markers are now available that may reliably indicate both perioperative myocardial infarction, as well as more subtle degrees of subclinical myocyte injury. In this review, the application of biochemical markers for clinical and research purposes during cardiac operation is considered.

Background: A high proportion of autologous saphenous vein grafts occlude as the result of intimal thickening. Blood vessels synthesize substances that may inhibit such intimal thickening. These include cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are stimulated by prostacyclin and nitric oxide, respectively. The prostacyclin-cAMP and nitric oxide-cGMP axes were therefore investigated in porcine vein grafts., Methods: Saphenous vein-carotid artery interposition graft procedures were carried out in pigs. One month after the operation, ungrafted saphenous veins, vein grafts, and carotid arteries were excised, the formation of cAMP and cGMP was assessed by radioimmunoassay, and the nitric oxide synthase content was determined by autoradiography., Results: The formation of cAMP and nitroprusside-stimulated cGMP was significantly diminished in vein grafts compared with ungrafted saphenous veins and carotid arteries. Calimycin-stimulated cGMP synthesis (nitric oxide release dependent) and the endothelial nitric oxide synthase content (autoradiography) were significantly elevated in vein grafts compared with ungrafted saphenous veins but were significantly less than those in carotid arteries., Conclusions: Adenylyl and guanylyl cyclase activity are down-regulated in vein grafts, which may contribute to the development of intimal and medial thickening. Nitric oxide release and endothelial nitric oxide synthase content are up-regulated in vein grafts, which is indicative of an adaptation to the arterial conditions of shear stress and pulsatile pressure.

Objectives: To investigate adenosine cyclic 3'5' monophosphate (cAMP) and guanosine cyclic 3'5' monophosphate (cGMP) synthesis in freshly isolated and surgically prepared human saphenous vein before and after culture., Setting: Bristol Heart Institute, Bristol, U.K., Methods: Freshly isolated and surgically prepared human saphenous vein was obtained from patients undergoing coronary artery bypass graft surgery. cAMP and cGMP synthesis, was assessed by radioimmunoassay in response to specific simulators in segments of saphenous veins after collection and following 14 days culture., Results: Immediately after collection there was a significant reduction in the synthesis of cAMP (forskolin and prostaglandin E1-stimulated) and cGMP (sodium nitroprusside-stimulated) in surgically prepared compared to freshly isolated saphenous veins. In contrast, following 14 days in culture, cAMP and cGMP synthesis was significantly elevated in surgically prepared compared to freshly isolated saphenous veins., Conclusions: These data indicate that surgical preparation results in a marked reduction in cyclic nucleotide synthesis in saphenous vein which may be relevant to the pathophysiology of early vein graft failure. The normalisation of both cAMP and cGMP synthesis in surgically prepared veins following 14 days culture indicates that cyclic nucleotide synthesising capacity may not be a major determinant of neointima formation in this experimental model.

The processes of angioplasty restenosis, vein graft failure, and transplant atherosclerosis, collectively termed 'syndromes of accelerated atherosclerosis', have been the focus of significant clinical and experimental research. Limitations of clinical studies have forced emphasis onto experimental animal models for the purpose of determining pathophysiology and evaluation of potential therapeutic strategies. However, the apparent failure of many in vivo animal models to predict interventional outcome in humans has raised doubt over their suitability as models of these pathophysiological states. Similar criticism has befallen the use of in vitro techniques for elucidating pathophysiology of the cellular elements. An awareness of the shortcomings of the various experimental models in use would therefore seem prerequisite both to a more critical evaluation of data generated from their use, and to the development of truly effective therapeutic strategies for humans.

There has been considerable interest in the use of normothermic techniques during cardiac operations, both as a means of myocardial protection and as a more physiologic environment for other organs during cardiopulmonary bypass. Although a limited number of uncontrolled studies have suggested superior clinical results compared with conventional hypothermic regimens, these claims have not been thoroughly investigated using randomized protocols. The limited available data suggest that the successful use of warm blood cardioplegia requires adequate delivery of the solution to all parts of the myocardium at optimal flow rates to maintain aerobic arrest, so those who advocate the use of normothermic arrest must pay particular attention to ensure that their myocardial protection is effective. The advantages of employing normothermic systemic perfusion in regard to factors such as improved hemodynamic performance and reduced blood loss postoperatively need to be balanced against concerns regarding the inadequacy of cerebral protection offered by this method.

Background: Migration and proliferation of vascular smooth muscle cells in the intima and superimposed atheroma are the main changes underlying late failure of saphenous vein bypass grafts. There is evidence that these events are partly modulated by complex interactions between inhibitors of vascular smooth muscle cell proliferation, such as prostacyclin (PGI2), and mitogens, such as leukotriene B4 (LTB4). Because the relative balance between these eicosanoids may play a role in vein graft failure, the synthesis of PGI2 and LTB4 was measured in porcine saphenous vein-carotid artery grafts 4 weeks after implantation and compared with ungrafted vein and common carotid artery from the same animal., Methods: Vessels were cut into 2-mm squares and preincubated in Dulbecco's minimum essential medium for 4 hours at 37 degrees C. Tissues were then further incubated with Dulbecco's minimum essential medium containing a range of concentrations of noradrenaline, arachidonate, and calcium ionophore A23187. Release of PGI2 and LTB4 into the supernatant was then assessed by radioimmunoassay., Results: In response to all stimulators, PGI2 release was markedly diminished in vein grafts compared with ungrafted saphenous veins and carotid arteries. The patterns of responses were similar in each vessel type. In contrast, LTB4 release was significantly enhanced in vein grafts compared to ungrafted saphenous veins and carotid arteries., Conclusions: These data indicate that there is a down-regulation of cyclooxygenase or PGI2 synthase in porcine vein grafts, which may constitute a further phenotypic change that would augment the hyperplastic process. Local increases in LTB4 synthesis in the vein graft, which indicates an induction of lipoxygenase and LTB4 synthase enzymes (and possibly reflects release from leukocytes which have infiltrated the graft), may contribute to increased intimal proliferation by direct promitogenic effects on smooth muscle cells.

Background: Pulmonary dysfunction is one aspect of the postoperative morbidity associated with cardiopulmonary bypass. Normothermic systemic perfusion can result in shorter intubation times, which have been attributed to improved pulmonary gas exchange, but the influence of perfusion temperature on pulmonary gas exchange itself is not known., Methods: Pulmonary gas exchange was assessed using alveolar-arterial oxygen pressure gradients in 45 patients undergoing routine coronary revascularization who were randomized to undergo cardiopulmonary bypass at 28 degrees C, 32 degrees C, or 37 degrees C. This was part of a more comprehensive study of the effects of temperature on bodily systems. The gradients were estimated preoperatively with the patients breathing air, again over a period between 2 and 4 hours postoperatively during mechanical ventilation with three different oxygen concentrations (30%, 40%, and 60%), and again 1 hour after extubation while breathing the same three oxygen concentrations., Results: Preoperative alveolar-arterial oxygen pressure gradients on air were 24.4 +/- 8.2 mm Hg (mean +/- standard deviation) (28 degrees C), 24.5 +/- 20.4 mm Hg (32 degrees C), and 20.5 +/- 9.5 mm Hg (37 degrees C). Postoperatively, during ventilation and after rewarming, the gradients increased with the increase in inspired oxygen fraction concentrations (30% to 60%) from 67.1 +/- 12.0 mm Hg to 193.1 +/- 30.5 mm Hg (28 degrees C), from 76.4 +/- 20.6 mm Hg to 246.7 +/- 47.7 mm Hg (32 degrees C), and from 79.0 +/- 18.0 mm Hg to 222.9 +/- 40.5 mm Hg (37 degrees C), respectively. A similar pattern was noted 1 hour after extubation, when the gradients increased from 72.4 +/- 12.5 mm Hg to 256.6 +/- 26.5 mm Hg (28 degrees C), from 75.7 +/- 13.9 mm Hg to 252.7 +/- 38.3 mm Hg (32 degrees C), and from 69.1 +/- 19.3 mm Hg to 253.1 +/- 33.0 mm Hg (37 degrees C). There were no significant differences in alveolar-arterial oxygen pressure gradient between the three groups during ventilation or after extubation., Conclusions: Cardiopulmonary bypass perfusion temperature does not influence alveolar-arterial oxygen pressure gradients in the first 12 hours after routine coronary artery bypass grafting in patients with uncompromised pulmonary and left ventricular function.

Background: The well-known correlation between prosthetic valve orifice area and transvalvular gradients has raised concerns about the presence of significant residual gradients when the size of the prosthesis that can be implanted is limited by the presence of a small aortic annulus., Methods: Dobutamine-stress Doppler echocardiography was used to evaluate the hemodynamic performance of small CarboMedics aortic prostheses (19 mm and 21 mm) in 18 patients (16 women; mean age, 64 years) who had undergone aortic valve replacement 23.5 +/- 19 months (standard deviation) previously. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-2 and increased to 10 and 20 micrograms.kg-1.min-2 at 15-minute intervals. Pulsed and continuous wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of both valves were calculated, and peak and mean velocity and pressure drop across the prostheses were measured., Results: Heart rate and cardiac output increased by 74% and 94%, respectively, and mean arterial blood pressure decreased by 9% at maximum stress. Effective orifice area, discharge coefficient, and performance index were comparable in both valve sizes at rest and maximum stress. Also, there was no significant difference in mean transvalvular pressure drop (gradient) for 19-mm and 21-mm prostheses at rest (8.1 +/- 8.4 and 4.8 +/- 3.8 mm Hg) or maximum stress (15.1 +/- 14.2 and 8.8 +/- 5.8 mm Hg, respectively). No significant correlation could be demonstrated between transvalvular pressure drop and patient's body surface area., Conclusions: These data show that 19-mm and 21-mm CarboMedics aortic prostheses exhibit equally favorable hemodynamic performance with minimal pressure gradient, both at rest and under stress conditions.

Background: The recent introduction of normothermic cardiopulmonary bypass (CPB) perfusion has raised concerns regarding the associated risk of renal dysfunction through its potential to exacerbate the systemic inflammatory response and end-organ injury. This study was designed to investigate the influence of CPB perfusion temperature on renal function., Methods: A prospective, randomized, controlled trial of CPB perfusion temperature (28 degrees C, 32 degrees C, and 37 degrees C) was performed in 30 patients undergoing routine coronary artery bypass grafting with normal preoperative renal function. Creatinine clearance was measured before induction of anesthesia, during CPB, and during every 12-hour period thereafter for 48 hours postoperatively. Glomerular and tubular function were assessed further by measurement of urinary creatinine, albumin, total protein, and retinol binding protein levels preoperatively, during CPB, and on days 1 and 3 postoperatively., Results: Creatinine clearance increased on CPB by 51% (28 degrees C), 185% (32 degrees C), and 112% (37 degrees C) (all p < 0.01 versus preoperative values) and returned to preoperative values by 24 hours postoperatively in all three groups. Urinary albumin/creatinine ratios rose significantly from a mean of 0.4 +/- 0.1 (standard deviation) to 10 +/- 12.5 (28 degrees C), from 0.55 +/- 0.3 to 5.2 +/- 4.9 (32 degrees C), and from 0.96 +/- 0.8 to 7.8 +/- 7.0 (37 degrees C) during CPB (all p < 0.001) but decreased gradually thereafter. Also, urinary total protein/creatinine ratios rose significantly from a mean of 0.009 +/- 0.007 to 0.034 +/- 0.02 (28 degrees C), from 0.01 +/- 0.006 to 0.026 +/- 0.01 (32 degrees C), and from 0.011 +/- 0.008 to 0.033 +/- 0.02 (37 degrees C) during CPB (all p < 0.005); however, there was a further increase by 24 hours, and ratios decreased gradually thereafter. Similarly, urinary retinol binding protein/creatinine ratios rose significantly in all three groups during CPB (all p < 0.0001) and increased further by 24 hours. There was no statistically significant difference between the renal markers in the three temperature groups in any of the observations., Conclusion: These data suggest that cardiopulmonary bypass perfusion temperature does not influence renal function in patients undergoing coronary artery bypass grafting.

Transesophageal echocardiography (TEE) now is used widely as a monitoring technique during and after cardiac operations. Widespread adoption of the technique has provided a wealth of new information. This review analyzes the influence of TEE on the routine conduct of cardiac operations and on surgical decision making in specific areas. Its use in routine hemodynamic monitoring and problem solving, both intraoperatively and postoperatively, is discussed. Transesophageal echocardiography has a particular role in valve operations, in guiding and assessing the immediate results of mitral valve repair. It also has found application in the grading and operative management of the severely atheromatous aorta, the diagnosis and management of aortic dissection, and other aspects of surgery of the thoracic aorta. In addition, management in specialized areas, such as cardiopulmonary transplantation and the insertion and monitoring of ventricular assist devices, have also been helped by the information provided by TEE.

Transesophageal echocardiography is becoming increasingly popular as a method of intraoperative monitoring because it can be performed continuously, does not transgress the sterile operative field, and provides data with regard to valve function, ventricular volumes, and contractility. Recently it was suggested that it can be used to measure cardiac output; however, controversy remains regarding its accuracy. Cardiac output was measured simultaneously by transesophageal echocardiography (using a 5-MHz pulse-wave Doppler, single-plane viewing probe) and by the thermodilution method in 21 patients undergoing open heart operations. The cardiac outputs measured by thermodilution correlated poorly (r = 0.45) with the transesophageal values derived from the left ventricular cross-sectional area, and the mean difference was 0.47 +/- 2.17 (standard deviation) L.min-1, giving limits of agreement of from -3.87 to +4.81 L.min-1. Cardiac outputs measured by thermodilution correlated well (r = 0.95) with transesophageal Doppler values derived from pulmonary artery flow velocity, with a mean difference of 0.12 +/- 0.45 L.min-1 and narrow limits of agreement of from -0.78 to +1.02 L.min-1. Based on our findings, transesophageal Doppler echocardiographic determination of cardiac output using pulmonary artery flow measurements can provide accurate hemodynamic data in patients undergoing cardiac operations.

Cross-sectional and M-mode echocardiography were used to review 33 patients 6-28 months (mean 19 months) after open heart surgery. Eleven patients had had echocardiographic signs of pericardial effusion during the first week after open heart surgery (Group A), and 22 had not (Group B). At review, pericardial effusion was found in 73% of subjects in Group A compared with 18% of those in Group B (P < 0.01). On average, posterior effusions were small (mean dimension in systole 0.9 cm) but they were detected reproducibly (interobserver agreement 97%). Anterior echo-free spaces (< 0.5 cm) were found frequently, but interobserver variation in their detection was high (agreement in 68%). Symptoms did not correlate with the presence of a late post-operative effusion but the groups were not matched for rhythm or ventricular function. Five patients in Group A had developed atrial fibrillation in association with their early post-operative effusion, and four of these had persisting atrial fibrillation at this review. These results suggest that echo-free spaces around the heart, suggestive of small pericardial effusions, may persist for many months after open heart surgery.

In this paper, we consider the results of thoracoscopy in a busy thoracic unit where the referring physicians place their greatest emphasis upon simple standard investigation of pleural disease. Between 1985 and 1989 620 patients with a pleural effusion of unknown aetiology were referred to our thoracic medical unit. Initial investigations included aspiration of pleural fluid for cytology and culture, and blind pleural biopsy for histological examination. Recourse to thoracoscopy was only taken in the absence of a diagnosis or non-resolution of the patients symptoms and signs. Of these 620 patients only 48 (8%) remained without a diagnosis and were referred for thoracoscopy. Histological assessment of biopsies obtained at thoracoscopy revealed malignancy in 24 patients (50%) and benign conditions in 16 patients (33%). In eight patients (17%) no conclusive diagnosis was established; in this latter group, six patients continued with their symptoms and further invasive investigations revealed malignancy. In this setting where thoracoscopy was used as a last resort, the sensitivity for thoracoscopy was 83% and the specificity was 100% with a predictive value of a negative result being 25%. In conclusion, from our experience, the majority of pleural disease may be diagnosed using simple techniques but thoracoscopy can be very helpful in the more complex cases. Moreover, inconclusive histology following thoracoscopy is an indication for further investigation if the condition does not improve.

To investigate the effect of recipient and donor genders on the outcome after heart transplantation, a retrospective survey was undertaken of 356 patients (366 transplants: 316 males, 40 females) undergoing transplantation between January 1979 and December 31, 1989, at Papworth Hospital. Ninety-three organs came from female donors; 263 organs came from males. Twelve females (30%; 95% confidence interval 16% to 44%) and 51 males (16%; 95% confidence interval 12% to 20%) died in the early postoperative period (within 90 days of operation). To date, two females (5%) and 51 males (16%) have died in the late postoperative period. Comparison between recipient genders showed no statistically significant difference in early mortality rates from any cause or in actuarial survival overall, although fatal acute rejection was significantly more common in female recipients (7 of 40 female recipients versus 19 of 316 male recipients). The higher incidence of fatal rejection among female recipients was related to the higher proportion of female donors in this group, because recipients of female donor grafts had significantly higher mortality rates, particularly in the early postoperative period and as a result of acute rejection, than did recipients of organs from male donors. Death from rejection after the first 3 months and death from infection were not gender-related. Recipients of grafts from female donors did not suffer significantly more early morbidity, such as rejection and infection, or late morbidity in the form of coronary artery disease. Acute rejection episodes were more common in female recipients.(ABSTRACT TRUNCATED AT 250 WORDS)

We investigated the effect of a novel surgical preparative technique for human saphenous vein by using the concentration of adenosine triphosphate and the adenosine triphosphate/diphosphate ratio to quantify medial integrity and by using stimulated rates of prostacyclin production to quantify endothelial function. Freshly isolated vein had an adenosine triphosphate concentration of 358 +/- 54 nmol.g-1 wet weight and an adenosine triphosphate/diphosphate ratio of 2.89 +/- 0.13 (n = 12); it produced prostacyclin in response to fluid shear at a rate of 14.3 +/- 2.0 pg.min-1.mg-1 wet weight (n = 12). Surgically prepared vein obtained on completion of the last proximal anastomosis had been distended with the patient's own arterial pressure using a side-arm connected to the aortic cannula. This vein had an adenosine triphosphate concentration of 413 +/- 70 nmol.g-1 wet weight and an adenosine triphosphate/diphosphate ratio of 2.74 +/- 0.44 (n = 11), and it produced prostacyclin at a rate of 13.1 +/- 0.2 pg.min-1.mg-1 wet weight (n = 12). All values were indistinguishable from those in freshly isolated vein. The results demonstrate that this simple technique for distention at arterial pressure preserved medial and endothelial function.

This study investigated whether intimal proliferation, the characteristic feature of the response of human saphenous vein to arterial implantation, also occurs in organ culture. Vein segments were maintained for 14 days in medium supplemented with 30% fetal bovine serum. Tissue viability (measured by adenosine triphosphate [ATP] concentration) decreased only 20% from 280 +/- 20 to 220 +/- 20 nmol/g wet weight. In veins prepared for culturing, endothelial loss (approximately 20%) was confined to near the cut edges. Cultured veins retained an endothelial layer in the initially undamaged areas, while the initially injured areas became covered by a mixture of endothelial and vascular smooth muscle cells. Autoradiography in conjunction with scanning electron microscopy showed the presence of proliferating cells on the intimal surface. Transverse sections of cultured veins showed the development of a new intima containing vascular smooth muscle cells identified by immunocytochemistry with anti-alpha-actin. There were also endothelial cells identified with Ulex europaeus lectin arranged in capillarylike structures. Pulse or continuous labeling of cultures with [3H]thymidine showed that proliferating cells were confined to the new intima and suggested that the smooth muscle cells in this layer arose from both immigration and proliferation. The results demonstrate that intimal proliferation occurs in organ culture of human saphenous veins.

A case of late cardiac tamponade seen with progressive dysphagia 15 days after aortic valve replacement is reported. The diagnosis was confirmed echocardiographically and successful pericardiocentesis was followed by immediate alleviation of the dysphagia.

Release of endothelium-derived relaxing factor was measured from freshly isolated human saphenous vein and from vein subject to routine surgical preparation for coronary artery bypass grafting. Surgical preparation led to a significant decline in endothelium-derived relaxing factor release as compared with freshly isolated vein, and these changes were associated with loss of endothelial coverage. Storage of freshly isolated vein in blood but not in Hartmann's solution also resulted in a decline in maximally stimulated endothelium-derived relaxing factor release that was not associated with loss of endothelium. Reduced production of endothelium-derived relaxing factor, a potent vasodilator and inhibitor of platelet adhesion and aggregation, may be implicated in the etiology of early vein graft thrombosis.