Consensus statement on aortic valve replacement via an anterior right minithoracotomy in the UK healthcare setting

The wide uptake of anterior right thoracotomy (ART) as an approach for aortic valve replacement (AVR) has been limited despite initial reports of its use in 1993. Compared with median sternotomy, and even ministernotomy, ART is considered to be less traumatic to the chest wall and to help facilitate quicker patient recovery. In this statement, a consensus agreement is outlined that describes the potential benefits of the ART AVR. The technical considerations that require specific attention are described and the initiation of an ART programme at a UK centre is recommended through simulation and/or use of specialist instruments in conventional cases. The use of soft tissue retractors, peripheral cannulation, modified aortic clamping and the use of intraoperative adjuncts, such as sutureless valves and/or automated knot fasteners, are important to consider in order to circumvent the challenges of minimal the altered exposure via an ART.A coordinated team-based approach that encourages ownership of the programme by team members is critical. A designated proctor/mentor is also recommended. The organisation of structured training and simulation, as well as planning the initial cases are important steps to consider.

Surgical aortic valve replacement in the era of transcatheter aortic valve implantation: a review of the UK national database

OBJECTIVES

To date the reported outcomes of surgical aortic valve replacement (SAVR) are mainly in the settings of trials comparing it with evolving transcatheter aortic valve implantation. We set out to examine characteristics and outcomes in people who underwent SAVR reflecting a national cohort and therefore 'real-world' practice.

DESIGN

Retrospective analysis of prospectively collected data of consecutive people who underwent SAVR with or without coronary artery bypass graft (CABG) surgery between April 2013 and March 2018 in the UK. This included elective, urgent and emergency operations. Participants' demographics, preoperative risk factors, operative data, in-hospital mortality, postoperative complications and effect of the addition of CABG to SAVR were analysed.

SETTING

27 (90%) tertiary cardiac surgical centres in the UK submitted their data for analysis.

PARTICIPANTS

31 277 people with AVR were identified. 19 670 (62.9%) had only SAVR and 11 607 (37.1%) had AVR+CABG.

RESULTS

In-hospital mortality for isolated SAVR was 1.9% (95% CI 1.6% to 2.1%) and was 2.4% for AVR+CABG. Mortality by age category for SAVR only were: <60 years=2.0%, 60-75 years=1.5%, >75 years=2.2%. For SAVR+CABG these were; 2.2%, 1.8% and 3.1%. For different categories of EuroSCORE, mortality for SAVR in low risk people was 1.3%, in intermediate risk 1% and for high risk 3.9%. 74.3% of the operations were elective, 24% urgent and 1.7% emergency/salvage. The incidences of resternotomy for bleeding and stroke were 3.9% and 1.1%, respectively. Multivariable analyses provided no evidence that concomitant CABG influenced outcome. However, urgency of the operation, poor ventricular function, higher EuroSCORE and longer cross clamp and cardiopulmonary bypass times adversely affected outcomes.

CONCLUSIONS

Surgical SAVR±CABG has low mortality risk and a low level of complications in the UK in people of all ages and risk factors. These results should inform consideration of treatment options in people with aortic valve disease.

Clinically significant incidental findings during preoperative computed tomography of patients undergoing cardiac surgery

With the development of minimally invasive cardiac surgery, chest and abdominal computed tomography (CT) scans are becoming an integral part of preoperative assessment and planning. Therefore, the number of incidental findings (IFs) detected with CT is rising. We aimed to investigate the frequency of clinically significant IFs on chest and abdominal CT scans performed during the preoperative assessment of patients undergoing adult cardiac surgery in a 2-year period. In a cohort of 401 patients (mean age 67.4 ± 12.3, female gender 28.9%, median logistic EuroSCORE 5.8 [0.9, 90.5]) who underwent chest or abdominal CT imaging during the study period, we identified 75 patients (18.7%) with clinically significant IFs who needed a further treatment or work-up to confirm the diagnosis or postoperative follow-up. Our data indicate that clinically significant IFs in patients referred for cardiac surgery are frequent. It is important to identify clinically significant Ifs, as a clear postoperative follow-up plan should be made.

Mitral valve annulus and circumflex artery: In vivo study of anatomical zones

Objective

To provide, with the use of preoperative coronary computed tomography angiography, an in vivo anatomical characterization of the relationship between the circumflex artery and mitral valve annulus to identify different risk classes and to increase the surgical awareness of those anatomical relations.

Methods

Ninety-five (mean age: 64.2 ± 11.7) consecutive patients, initially referred for elective minimally invasive mitral valve surgery, underwent preoperative coronary computed tomography angiography. The distance between the circumflex artery and mitral annulus was assessed using 6 points designed on the posterior mitral annulus, starting from the anterolateral to the posteromedial commissure; this design created an ideal 5-zone system. High-risk anatomy was defined as a distance less than 3 mm between the circumflex artery and the mitral valve annulus.

Results

The shortest distance between the circumflex artery and mitral valve annulus was observed at the area between the anterolateral commissure and the midpoint of P1 scallop, so-called zone 1 (5.49 ± 3.13 mm), whereas the longest distance occurred at zone 5 (12.03 ± 4.93). Twenty-four patients (25%) were identified with high-risk anatomy (mean distance 1.94 ± 0.8 mm). Left dominant and co-dominant hearts demonstrated a shorter circumflex artery-mitral valve annulus distance at all the zones. At multinomial logistic regression, the pattern of coronary dominance and the size of the circumflex artery were independent factors for high-risk anatomy.

Conclusions

Coronary computed tomography angiography is a useful investigation to identify patients at risk of circumflex artery flow disturbance; for high-risk anatomy, this knowledge may enhance a safer operative technique.

Dramatic resolution of an immediate postoperative distortion of the circumflex artery during mitral valve surgery

Injury or distortion of the circumflex coronary artery can occur during mitral valve surgery, due to its proximity to the mitral valve annulus. We present the case of a 72-year-old male patient with symptomatic mitral regurgitation, who underwent minimally invasive mitral valve surgery. The initial reparative gesture was complicated by intraoperative infarct due to a distortion of the circumflex artery (CX) caused by the rigidity of the ring used; the mainstay of the treatment was the removal of the previous device implanted in favor of a flexible one with restitutio ad integrum of the CX patency.

Management of refractory bleeding post-cardiopulmonary bypass in an acute heparin-induced thrombocytopenia type II renal failure patient who underwent urgent cardiac surgery with bivalirudin (Angiox®) anticoagulation

Acute heparin-induced thrombocytopenia (HIT) patients present a myriad of anticoagulation management challenges, in clinical settings where unfractionated heparin (UFH) is the traditional drug of choice. UFH use in cardiac surgery is a known entity that has been subject to rigorous research. Research has, thus, led to its unparalleled use and the development of well-established protocols for cardiac surgery. In comparison to UFH, bivalirudin use for acute HIT patients requiring urgent cardiac surgery with cardiopulmonary bypass (CPB) is still in its infancy. We describe the tailored post-CPB management of refractory bleeding in a 65-year-old infective endocarditis, acute HIT patient with renal failure who underwent urgent aortic valve replacement and mitral valve repair with bivalirudin anticoagulation. A management approach that entailed a combination of continuous venovenous haemofiltration (CVVH), 4-Factor prothrombin complex concentrate (PCC) (Beriplex), recombinant factor VIIa (rFactor VIIa) and desmopressin (DDAVP) were consecutively used post-operatively in theatre. Based on this case study experience, two modifications to institutional protocols are recommended. The first is the use of CVVH in theatre to eliminate bivalirudin in renal failure patients or in patients where bivalirudin elimination is prolonged. Secondly, a ‘rescue therapy/intervention’ algorithm for the swift identification of refractory bleeding post-CPB is also recommended. Rescue therapy agents, such as a 4-Factor PCCs and rFactor VIIa, should be incorporated into the protocol after a robust evidence-based search and agreement with the haematologist. The aim of these recommendations is to reduce the risk of bleeding associated with bivalirudin use for inexperienced institutions and experienced institutions alike, until larger randomized, controlled studies provide more in-depth knowledge to expand our clinical practice.

Satisfaction with conduit harvest site scars in coronary bypass surgery

INTRODUCTION

Scars from conduit harvesting are common in coronary artery bypass patients. As an outward manifestation of surgery, the scar is important in patient perception of operative success and quality of care received. The aim of this study was to determine patient satisfaction with scars from radial artery and saphenous vein harvests at a tertiary cardiothoracic centre.

METHODS

We surveyed 62 patients attending follow-up appointment using the Patient Scar Assessment Questionnaire. This is a reliable and valid measure of a patient's perception of scarring. Data were analysed using ratings of scar attributes and features. We compared findings according to site and patient choice of scar site using the Mann-Whitney U test.

RESULTS

Analysis of both global and summative ratings showed no overall statistical differences between arm and leg scars (p<0.05). However, patients given a choice gave significantly higher ratings of scar appearance on global ratings versus those given no choice. Patients also reported greater satisfaction with appearance than those given no choice on summative ratings (p<0.05).

CONCLUSIONS

Patient choice of conduit site is an important determinant of the overall rating of scar appearance. Overall satisfaction is influenced by scar appearance. Clinicians should ensure, wherever possible, that they involve patients in conduit site selection.

Infective endocarditis in a parachute-like asymmetrical mitral valve

A 21-year-old woman was admitted to our unit with suspected infective endocarditis. Transthoracic and transoesophageal echocardiogram demonstrated vegetation in a parachute-like asymmetrical mitral valve with severe mitral regurgitation. She was completely asymptomatic before this presentation. Though there was no evidence of mitral stenosis, this deformity is associated with transvalvular turbulence, which would account for the increased likelihood of infective endocarditis. She underwent a prosthetic mitral valve replacement with a 21 mm ATS mechanical valve.

Microwave surgical ablation for atrial fibrillation during off-pump coronary artery surgery using total arterial-Y-grafts: an early experience

This study demonstrates the efficacy and eligibility of concomitant epicardial microwave AF (MWAF) ablation during off-pump arterial revascularisation using the left internal mammary to radial 'Y' graft (OPCABy) in patients with permanent and paroxysmal atrial fibrillation. From June 2004 to December 2005, sixteen consecutive patients were offered MWAF ablation and OPCABy. AF was permanent in 11 cases and paroxysmal in five. The MWAF ablation protocol exploited the use of either the Flex 4 or Flex 10 probe (Afx- Guidant, Santa Clara, CA). Spontaneous cardioversion was used to demonstrate conduction block. Data were collected prospectively. Patients were followed-up in outpatient clinic at 6 weeks, 3 months and 6 months after discharge. Sinus rhythm was seen in 75%, 67% and 71% of patients at conclusion of surgery, and 3 and 6 months postoperatively. Cardioversion to sinus rhythm was seen in 67% of patients with permanent AF and 80% of patients with paroxysmal AF. Spontaneous cardioversion at operation occurred in 12 patients, all of whom were in sinus rhythm at six months. The use of MWAF ablation during concomitant OPCABy surgery is an effective therapy in the short- to medium-term. Spontaneous return to sinus rhythm is a reliable intraoperative indicator of long-term success.

Wire perforation of Flex 10 microwave device during thoracoscopic atrial fibrillation ablation

OBJECTIVES

Rapid advances in technology are increasing the repertoire of techniques available for the surgical treatment of atrial fibrillation (AF). These techniques utilize new devices which are normally safe. However, potential problems can arise with a new device as is illustrated in this report.

METHODS

A 58-year-old man underwent a thoracosopic AF ablation utilizing the Flex 10 probe (Guidant, Afix, Fremont, CA).

RESULTS

We experienced an important device failure following thoracoscopic microwave AF ablation that has not been reported to date.

CONCLUSIONS

Although new devices seem to be safe, potential problems often emerge with time, and clinicians pioneering these technologies have an obligation to report these experiences to the wider surgical community.

Anatomic feasibility of creating an inferior epigastric arterio-venous fistula to develop the internal thoracic artery with a view to coronary grafting

Arterio-venous fistulae increase the diameter of their feeding artery. It may be advantageous to increase the diameter of the internal thoracic artery before its use for coronary grafting. A fistula applied directly to the internal thoracic artery may compromise its subsequent use as a coronary graft and is technically difficult and invasive. However, in view of the continuity between the internal thoracic artery and the inferior epigastric artery, it is possible to achieve the same effect by constructing a fistula on the latter. The purpose of this work was to determine, in a cadaveric study, the feasibility of carrying out an arterio-venous fistula on the inferior epigastric artery so as to increase the caliber of the internal thoracic artery before coronary grafting. A morphologic study of the inferior epigastric artery and its vein and their relations as well as the feasibility of such a fistula was carried out on 10 cadavers. The epigastric artery measured 12.35+/-1.2 cm in length. Its diameter decreased from its origin towards it termination from 3.16+/-0.26 cm to 1.76+/-0.18 cm. There was a constant connection between the inferior and superior epigastric arteries. This connection was single in 30% of cases, double in 50% and through an anastomotic plexus of more than two vessels in 20%. The mean number of anastomotic connections was 1.8. The epigastric vein was constant with a diameter of 0.75+/-0.06 mm at its origin and only sufficiently large to carry out a fistula at its termination (2.6+/-0.9 mm). In conclusion, this study indicates that it should be relatively simple to create a fistula between the inferior epigastric artery and either the inferior epigastric vein or the external iliac vein.

Intraoperative confirmation of ulnar collateral blood flow during radial artery harvesting using the "squirt test"

Hand ischemia is a major concern after radial artery harvesting for coronary revascularization. Although a number of preoperative tests have been described to assess the adequacy of ulnar collateral blood flow, many of them are subjective and unreliable. In addition, the presence of arterial connections between the radial and ulnar systems in the elbow and forearm and variability in forearm angiology imply that assessment of alternative blood supply to the hand can only be made once collateral branches of the radial artery have been divided. We describe a technique for intraoperative assessment of ulnar collateral blood flow after mobilization and division of collateral branches of the radial artery.

Surgical correction of postpneumonectomy stridor by saline breast implantation

Postpneumonectomy syndrome is a rare complication of pneumonectomy and is characterized by progressive dyspnea, stridor, and repeated chest infections. It is caused by displacement and rotation of the mediastinal structures into the pneumonectomy space, producing compression and malacic changes in the trachea and remaining bronchus. We report the successful long-term results of mediastinal correction, cardiopexy and plombage with saline breast prostheses in a 59-year-old man after right pneumonectomy for carcinoma of the lung.

Effect of surgical training on outcome and hospital costs in coronary surgery

BACKGROUND

There is a perceived conflict between the need for service provision and surgical training within the National Health Service (NHS). Trainee surgeons tend to be slower (thereby reducing theatre throughput), and may have more complications (increasing hospital stay and costs).

OBJECTIVE

To quantify the effect of training on outcome and costs.

DESIGN

Data on 2740 consecutive isolated coronary artery bypass (CABG) operations were analysed retrospectively. Redo and emergency procedures were excluded. The seniority of the operating surgeon was related to operating times, risk stratified outcome, and overall hospital costs.

SETTING

Regional cardiothoracic surgery unit.

MAIN OUTCOME MEASURES

Postoperative mortality; hospital costs.

RESULTS

Consultants, senior trainees, intermediate trainees, and junior trainees performed 1524, 759, 434, and 23 procedures, respectively. Trainees at the three different levels were directly supervised by a consultant in 55%, 95%, and 100% of cases. The unadjusted mortalities were 3.2%, 2.0%, 2.3%, and 4.3%, respectively (NS). There were no significant differences between the groups with respect to time in the intensive care unit and length of hospital stay. The mean cost per patient was pound6619, pound6572, pound6494, and pound6404 (NS).

CONCLUSIONS

Trainees performed 44.4% of all CABG operations. There was no detrimental effect on patient outcome, length of hospital stay, or overall hospital costs. There need be little conflict between service and training needs, even in hospitals with extensive training programmes.

Emergency reinstitution of cardiopulmonary bypass following cardiac surgery: outcome justifies the cost

OBJECTIVE

Crash back on bypass (crash-BOB) is occasionally required in the resuscitation of patients developing life-threatening complications following cardiac surgery. This study aims to determine the incidence, aetiology and cost-effectiveness of such intervention.

METHODS

Retrospective review of all crash-BOB patients over 5.5 years at one hospital.

RESULTS

The incidence of crash-BOB was 0.8% and occurred at a mean of 7 h post-operatively (range 1 h-20 days). Pre-operative Parsonnet scores were similar to the overall population of patients undergoing surgery in our institution (mean score 10; range 0-45). The original cardiac operations were coronary revascularization (39), valve surgery (12) and others (4). Indications for crash-BOB were cardiac arrest (23), bleeding (20), hypotension (7), ischaemia (1) and others (4). Of the 55 patients, 20 died on the operating table. Of the remaining 35, a further 12 died in hospital. Overall survival was therefore 42%. Where crash-BOB was for bleeding, 17 of 20 patients (85%) survived to leave theatre, of whom 11 patients (55%) left hospital alive. In the 35 non-bleeders, only 18 (51%) survived crash-BOB and 12 (34%) left hospital alive. Sixteen patients required a second period of aortic cross-clamping of whom 13 (81%) survived to leave theatre, and 11 (69%) left hospital alive. Conversely, of nine patients in whom no specific diagnosis was found during crash-BOB, only two (22%) survived the procedure and none survived to hospital discharge. Multiple logistic regression identified pre-operative Parsonnet score (P=0.045) and the need for aortic cross-clamping to deal with an identified surgical problem (P=0.03) as significant predictors of hospital survival. Indication for crash-BOB (bleeder/non-bleeder) failed to reach significance (P=0.08). Age, sex, intra-aortic balloon pump use at the primary procedure, and time following the primary procedure to crash-BOB were not identified as predictors of hospital survival. Of the 23 hospital survivors, three patients suffered a stroke post-operatively and made a good functional recovery prior to discharge. Two patients developed sternal wound dehiscence requiring surgical rewiring. At follow-up (mean 3 years, range 1-6 years), 19 patients were in NYHA class I and four were in class II. Crash-BOB patients required an average of 8 extra intensive care days and 2 extra ward days. The total cost of these resources was pound164900 (including theatre time, cardiopulmonary bypass and intra-aortic balloon pump use). This was equivalent to pound7170 per life saved.

CONCLUSIONS

Crash-BOB occurred in 0.8% of cases and was associated with a survival to discharge of 42%, and a justifiable cost of only pound7170 per life saved. Establishing an accurate diagnosis for the cause of clinical deterioration resulting in crash-BOB intervention was important, and the need for a further period of aortic cross-clamping did not preclude a favourable outcome.

The effects of cardiopulmonary bypass temperature on inflammatory response following cardiopulmonary bypass

OBJECTIVES

The inflammatory response to cardiopulmonary bypass is believed to play an important role in end organ dysfunction after open heart surgery and may be more profound after normothermic systemic perfusion. The aim of the present study was to investigate the effects of cardiopulmonary bypass temperature on the production of markers of inflammatory activity after coronary artery surgery.

METHODS

Forty-five low risk patients undergoing elective coronary artery surgery were prospectively randomized into three groups: hypothermia (28 degrees C, n = 15), moderate hypothermia (32 degrees C, n = 15), and normothermia (37 degrees C, n = 15). All patients received cold antegrade crystalloid cardioplegia and topical myocardial cooling with saline at 4 degrees C. Serum samples were collected for the estimation of neutrophil elastase, interleukin 8, C3d, and IgG under ice preoperatively, 5 min after heparinisation, 30 min following start of CPB, at the end of CPB, 5 min after protamine administration, and 4, 12 and 24 h postoperatively.

RESULTS

Patients were similar with regard to preoperative and intraoperative characteristics (age, sex, severity of symptoms, number of grafts performed, aortic cross clamp time, cardiopulmonary bypass time). Neutrophil elastase concentration increased markedly as early as 30 min after the onset of cardiopulmonary bypass and peaked 5 min after protamine administration. Levels were not significantly different between the three groups. A similar finding was apparent for C3d release. Interleukin 8 concentrations also demonstrated a considerable increase related to cardiopulmonary bypass in all groups, but there was a significantly more rapid decline in interleukin 8 concentrations in the normothermic group in the postoperative period. Eluted IgG fraction showed a much earlier peak concentration than the other markers, occurring within 30 min of the start of cardiopulmonary bypass. Levels reached a plateau, before declining soon after the end of bypass and remained higher than preoperative values at 24 h. There was no difference between the three groups. The cumulative release of all markers was calculated from the concentration-time curves, and was not statistically different between groups.

CONCLUSION

Normothermic systemic perfusion was not shown to produce a more profound inflammatory response compared to hypothermic and moderately hypothermic cardiopulmonary bypass.

Current practice in thoracic sympathectomy

Thoracic sympathectomy has been performed for many years. With the recent development of video assisted thoracic surgical techniques the indications for surgery have increased, and the outcome is much better.

Influence of normothermic systemic perfusion temperature on cold myocardial protection during coronary artery bypass surgery

OBJECTIVE

To determine the effect of normothermic systemic perfusion on myocardial injury when using cold cardioplegic techniques in patients undergoing coronary artery bypass surgery.

METHOD

Sixty six patients with stable angina pectoris were prospectively randomized into three groups according to cardiopulmonary bypass temperature: hypothermia (28 degrees C, n = 22), moderate hypothermia (32 degrees C, n = 22) and normothermia (37 degrees C, n = 22). All patients received cold antegrade crystalloid cardioplegia and topical cooling with saline at 4 degrees C. Serum samples were collected for troponin T and I estimation preoperatively, 4 hours after removal of the aortic cross clamp, and 12, 24, 36 and 48 hours postoperatively. In addition, serial electrocardiographic studies were undertaken on days 1, 3 and 5.

RESULTS

Patients were similar with regard to preoperative and intraoperative characteristics Four patients showed ECG changes typical of perioperative myocardial infarction but remained clinically well (28 degrees C, one; 32 degrees C, one; 37 degrees C, two). In the remaining 62 patients, serum troponin T increased significantly from a mean baseline value of 0.02 ng/ml to 1.5+/-0.9 ng/ml 4 hours after removal of the aortic cross-clamp (P<0.0001). Similarly, troponin I increased from 0.06 ng/ml to 0.63+/-0.47 ng/ml 12 hours after reperfusion (P<0.0001). Serum concentrations of both markers subsequently declined with time but remained higher than preoperative values at 48 hours. There were no differences between the three groups with respect to peak and cumulative serum troponin release. Normothermic cardiopulmonary bypass did not compromise the efficacy of cold myocardial protection when assessed by serum troponin concentrations in low risk patients undergoing coronary revascularization.

Hemodynamic performance of the 21-mm St. Jude BioImplant prosthesis using dobutamine Doppler echocardiography

This study examines the hemodynamic performance of small size St. Jude BioImplant aortic prostheses using dobutamine echocardiography. Eleven patients (3 women, mean age 75 years) who had undergone aortic valve replacement with a size 21-mm St. Jude BioImplant aortic prostheses at 10.8 +/- 5.1 months (SD) previously were studied. Dobutamine infusion was started at a rate of 5 microg/kg/min and increased to 10 microg/kg/min, and subsequently to 20 microg/kg/min at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, mean gradient, and the performance index across each prosthesis were calculated and cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract. Stress dobutamine increased heart rate and cardiac output by 51% and 56%, respectively (both p <0.0001), and the mean transvalvular gradient increased from 30.1 +/- 7.5 mm Hg at rest to 49.3 +/- 11.5 mm Hg at maximum stress (p <0.0005). The performance index increased progressively from 0.29 +/- 0.05 at rest to 0.40 +/- 0.10 at maximum stress (p <0.0005). Regression modeling analyses demonstrated that the maximum stress gradient was independent of all variables except the resting gradient (p = 0.03). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress. Thus, these data demonstrate that the size 21-mm St. Jude BioImplant prosthesis exhibits suboptimal hemodynamic performance with transvalvular gradients consistent with mild to moderate aortic stenosis, both at rest and under stress conditions.

Left ventricular volume reduction surgery

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.

Influence of normothermic systemic perfusion during coronary artery bypass operations: a randomized prospective study

OBJECTIVES

Normothermic cardiopulmonary bypass has been proposed as a more physiologic technique than hypothermic bypass for the maintenance of the body during cardiac surgery. The aims of this study were to investigate the effects of systemic perfusion temperature on clinical outcome after coronary revascularization.

METHODS

Three hundred patients (mean age 60 +/- 9 years, 88% male) were prospectively randomized into three groups: hypothermia (28 degrees C, n = 100), moderate hypothermia (32 degrees C, n = 100), and normothermia (37 degrees C, n = 100). All patients received cold antegrade St. Thomas' Hospital crystalloid cardioplegic solution, and patients in the normothermic group were actively rewarmed during cardiopulmonary bypass (nasopharyngeal temperature 37 degrees C).

RESULTS

No differences were found between groups with respect to mortality (1%), intraaortic balloon pump use, perioperative infarction rates, focal neurologic deficits (1%), intubation time, intensive care unit stay, and postoperative hospital stay. Further stepwise regression analysis identified age and intensive care unit stay as important predictors of the variability in postoperative stay (both R2 = 0.114; p < 0.001), whereas perfusion temperature remained a nonsignificant explanator. Normothermic perfusion necessitated larger doses of phenylephrine to maintain arterial pressure above 50 mm Hg during cardiopulmonary bypass (p < 0.0001 vs 28 degrees C, p < 0.01 vs 32 degrees C) but less requirement for electrical defibrillation during reperfusion (p < 0.05 vs 32 degrees C, p < 0.01 vs 28 degrees C). Total chest drainage was not different between groups, but patients undergoing normothermic cardiopulmonary bypass required less transfusion of blood (p < 0.05 vs 28 degrees C and 32 degrees C) and platelets (p < 0.04 vs 32 degrees C, p < 0.001 vs 28 degrees C) in the postoperative period.

CONCLUSIONS

Cardiopulmonary bypass temperature did not influence early clinical outcome after routine coronary artery bypass operations. Normothermic systemic perfusion was associated with an increased requirement for vasoconstrictors and reduced requirements for electrical defibrillation and transfusion of blood products.

Cardiac troponin T and troponin I release during coronary artery surgery using cold crystalloid and cold blood cardioplegia

OBJECTIVE

To evaluate and compare myocardial protection using cold crystalloid and blood cardioplegia by measuring release of cardiac Troponin T and Troponin I during coronary artery surgery.

METHODS

Forty two patients undergoing myocardial revascularization were prospectively randomised into two groups in whom myocardial protection was achieved with either antegrade cold (4 degrees C) crystalloid (CCP) (n = 21) St. Thomas' I cardioplegic solution. Serial venous blood samples were collected for measurement of cardiac Troponin T and Troponin I, prior to induction of anesthesia and at 4, 12, 24 and 48 h after removal of the aortic cross clamp.

RESULTS

There were no hospital deaths in the two groups and one patient in each group suffered a perioperative myocardial infarction. Rising levels of Troponin T and Troponin I were found in all patients. Serum concentrations increased as early as 4 h after removal of the aortic cross clamp, and reached a peak at 12 h postoperatively in both groups. These levels subsequently declined, but remained higher than preoperative values at 48 h. There were no differences between the two groups with respect to serum Troponin T and I release at 4, 12, 24 and 48 h, area under the respective curves, and peak Troponin T and I release. Serum Troponin levels were significantly higher in patients with unstable angina and in two patients who suffered a perioperative myocardial infarction.

CONCLUSION

Serum release of cardiac Troponin T and Troponin I is significantly raised in low risk patients undergoing myocardial revascularization. This release is similar when either cold crystalloid or cold blood cardioplegia are used. This may imply that both methods offer identical protection to the myocardium in a low risk group of patients.

Biochemical markers of myocardial injury during cardiac operations

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.

Hemodynamics of St. Jude Medical prostheses in the small aortic root: in vivo studies using dobutamine Doppler echocardiography

BACKGROUND AND AIMS OF THE STUDY

The well known correlation between prosthetic valve orifice area and transvalvular pressure drop has raised concerns about the presence of significant residual gradients when only a small-sized prosthesis can be implanted, particularly in patients with a large body surface area. The aim of this study was to study the hemodynamic performance of small-size St. Jude Medical aortic prostheses using dobutamine echocardiography.

METHODS

Fifteen patients (14 females, one male, of mean age 67 years) who had undergone aortic valve replacement with size 19 mm St. Jude Medical prostheses at a mean of 19 +/- 8 (SD) months previously were studied. Dobutamine infusion was started at a rate of 5 micrograms/kg/min and increased to 10 and subsequently to 20 micrograms/kg/min at 15-min intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area (EOA) and mean gradient across each prosthesis were calculated, and cardiac output (CO) was determined by Doppler measurement of flow in the left ventricular outflow tract.

RESULTS

Dobutamine-stress increased heart rate and cardiac output by 57% and 86% respectively (both p < 0.0005), and mean transvalvular gradient increased from 22.0 +/- 4.9 mmHg at rest to 41.9 +/- 9 mmHg at maximum stress (p < 0.0001). Regression modeling analyses demonstrated that maximum stress gradient was independent of all variables except resting gradient (p = 0.0068). Body surface areas had no effect on the changes in cardiac output, effective orifice area or transprosthetic gradient at maximum stress.

CONCLUSIONS

These data demonstrate that the size 19 mm St. Jude Medical prosthesis exhibits favorable hemodynamic performance. Transvalvular gradients remained within a clinically acceptable range, both at rest and under stress conditions. Moreover, in the patient population studied, overall hemodynamic performance indicates that with St. Jude Medical aortic valves, patient-prosthesis mismatch is unlikely to be a problem of clinical importance.

The effects of cardiopulmonary bypass temperature on neuropsychologic outcome after coronary artery operations: a prospective randomized trial

The effect of systemic perfusion temperature on postoperative cognitive function was investigated in 96 adult patients undergoing elective coronary revascularization with cardiopulmonary bypass at 28 degrees C, 32 degrees C, or 37 degrees C. Neuropsychologic performance was assessed 1 day before the operation and 6 weeks after the operation. Five tests were adapted from the Wechsler Adult Intelligence Scale and two from the Wechsler Memory Scale.

RESULTS

No patients had major neurologic complications. Ninety-three patients completed the five Wechsler Adult Intelligence Scale tests, but only 70 went on to complete the Wechsler Memory Scale tests as well. In these, there was an effect of cardiopulmonary bypass temperature on the number of neuropsychologic tests in which there was a preoperative to postoperative deterioration (p = 0.021), the number with bypass at 37 degrees C being significantly greater than the number with bypass at 32 degrees C (p = 0.015). Subsidiary analyses using a multivariate linear model examined the effect of cardiopulmonary bypass temperature on the magnitude of change, with or without allowing for other possible confounding influences. There was an adverse effect of normothermic (37 degrees C) versus moderately hypothermic (32 degrees C) perfusion---more convincingly displayed in the analyses of all seven scores rather than just the Wechsler Adult Intelligence Scale scores. Further cooling to 28 degrees C conferred no additional benefit in terms of cognitive function. The importance of the deterioration is open to question.

Normothermic techniques during open heart operations

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.

Comparison of hemodynamic performances of St. Jude Medical and CarboMedics 21 mm aortic prostheses by means of dobutamine stress echocardiography

Dobutamine stress Doppler echocardiography was used to compare the hemodynamic performance of two small aortic bileaflet prostheses. Nineteen patients (14 female, mean age 64 years) who had undergone aortic valve replacement with 21 mm bileaflet valve prostheses (St. Jude Medical valve, n = 9, or CarboMedics valve, n = 10) were studied. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-1 and increased to 10 and 20 micrograms.kg-1.min-1 at 15-minute intervals. Under maximum stress, heart rate and cardiac output increased by 70% and 120%, respectively, and mean arterial blood pressure decreased by 9%. Pulsed-wave and continuous-wave Doppler studies were performed at rest and at the end of each stage. Velocity ratio, effective orifice area, performance index, and discharge coefficient of the valve were calculated, and peak and mean velocities and pressure drops across the prostheses were measured. Dobutamine infusion produced similar increases in cardiac output in all patients. Effective orifice areas, discharge coefficients, and performance indexes were comparable for the two valve groups both at rest and maximum stress. Transvalvular velocities and pressure drops were also similar in the two valve groups. Transvalvular pressure drops were also comparable in patients with large body surface area. Dobutamine stress echocardiography is useful in the evaluation of the hemodynamic performance of prosthetic heart valves. St. Jude Medical and CarboMedics 21 mm prostheses have equally favorable hemodynamic performances in most patients under conditions of high cardiac output.

Effects of cardiopulmonary bypass temperature on pulmonary gas exchange after coronary artery operations

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.

In-hospital audit underestimates early postoperative morbidity after cardiac surgery

BACKGROUND

The demand for open heart surgery has driven current practice towards early postoperative discharge and interhospital transfer to maximise patient throughput. The extent to which this redirects morbidity to other healthcare providers is unknown.

OBJECTIVE

To define the incidence of inhospital and early postoperative morbidity within 6 weeks of primary hospital discharge after cardiac surgery.

DESIGN

Prospective inhospital data for 322 consecutive adult patients undergoing cardiac surgery were compared with retrospective information obtained by postal questionnaire.

RESULTS

Mean (SD) primary postoperative hospital stay was 8.3 (3.1) days. There were 13 inhospital deaths (4%), and three patients died within 6 weeks of primary discharge. Retrospective information was obtained from 297 patients (96%). Of these, 77% patients were discharged home directly, while 23% were transferred to other hospitals for continued medical care. Mean (SD) hospital stay after transfer was 12 (8.4) days and required 741 additional hospital bed days. Thirty nine patients (13%) were readmitted to hospital, requiring a further 275 hospital bed days. The readmission rate was lower in patients sent home directly (10%), than in those who were transferred (22%; P < 0.001).

CONCLUSIONS

Inhospital audit underestimates early morbidity after cardiac surgery. The burden transferred to other healthcare providers is considerable and has important financial implications for purchasers.

Evaluation of the hemodynamic performance of small CarboMedics aortic prostheses using dobutamine-stress Doppler echocardiography

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.

Cardiopulmonary bypass perfusion temperature does not influence perioperative renal function

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.

Thrombolytic therapy for left sided prosthetic heart valve thrombosis

In order to clarify the role of thrombolytic therapy for the treatment of left sided prosthetic valve thrombosis, a composite analysis of 158 cases reported in the English literature was undertaken. Complete success of therapy was achieved in 68.4% of patients, and the results were better in patients with aortic compared to mitral valve prostheses (p < 0.01), in those presenting in lower NYHA class (p < 0.01), and with acute rather than chronic symptoms (p < 0.05). A successful outcome was seen more frequently with tilting disc than bileaflet valves (p < 0.001). Overall mortality during therapy was 7%. Cerebral embolic events were observed in 9.5% of patients, and irreversible neurological injury occurred in 4.4%. The rethrombosis rate was 17% and the incidence of late death was 6.3%. Thrombolysis may be a useful therapeutic alternative for left sided prosthetic valve thrombosis in patients with a perceived contraindication to surgery. The risks of systemic clot embolization along with incomplete resolution of valve leaflet motion or rethrombosis limits any recommendation for more widespread use.

Laparoscopic cholecystectomy in Leicester: an audit of 555 patients

Laparoscopic techniques have revolutionised the surgical approach to cholecystectomy, even though there have been no published randomised controlled trials to demonstrate the safety of this approach. We present an audit of 555 patients offered laparoscopic cholecystectomy. In all, 54 patients (9.7%) were converted to an open procedure. Peroperative cholangiography (POC) was attempted in 190 cases (34.2%) and achieved in 141 (25.4%). Major complications occurred in 26 cases (4.7%) including 5 (0.9%) deaths, two of whom had major pre-existing morbidity. There was one common bile duct (CBD) injury (0.18%). There were 30 patients (5.4%) found to have CBD stones, 27 of which were cleared at ERCP, and three converted to open exploration. Cholecystectomy by any route is a major operation and we conclude that careful case selection remains imperative. However, morbidity is favourable compared with open cholecystectomy, and comparable with other reports using the laparoscopic technique. Our experience of CBD injury (0.18%) is also acceptable compared with the risk of injury during open cholecystectomy. There were 312 patients (56.2%) who did not undergo perioperative CBD imaging with ERCP or POC and three of these developed early symptomatic retained stones. This group requires further follow-up.

The substrate determines the rate and pattern of neutral lipid synthesized by isolated human sebaceous glands

Lipogenesis from different substrates was determined in isolated human sebaceous glands after 17-20 h in culture. Rates of total lipogenesis were 1003 +/- 141, 842 +/- 90, 481 +/- 57 pmol.h-1 gland-1 +/- SE from acetate, lactate and glucose, respectively, when present as sole substrates: the rate from glucose was significantly lower (P less than 0.01). Squalene synthesis was greatest from acetate at 479 +/- 44 pmol.h-1.gland-1; significantly higher than from lactate (281 +/- 45 pmol.h-1.gland-1) or glucose at 119 +/- 18 pmol.h-1.gland-1. Wax ester plus cholesterol ester synthesis showed similar dependence on substrate but triglyceride synthesis was unaffected. We conclude that the added substrate determines both the rate and pattern of non-polar lipid synthesized by isolated human sebaceous glands.