Removal of a bullet in the pericardial cavity by video-assisted thoracoscopic surgery

The use of video-assisted thoracoscopic surgery (VATS) in dealing with thoracic trauma has been well established. VATS avoids a thoracotomy and offers excellent visualization of the entire pleural cavity. The removal of bullets from the pleural cavity using VATS has also been reported, but, to our knowledge, this is the first time a bullet has been removed from the pericardial cavity using VATS.

Risk factors and mortality associated with deep sternal wound infections following coronary bypass surgery with or without concomitant procedures in a UK population: a basis for a new risk model?

Deep sternal wound infection (DSWI) is a rare but serious complication following coronary artery bypass surgery. Our study investigates the risk factors and mortality associated with DSWI with other risk models for DSWI. Data was collected prospectively on 7602 patients undergoing coronary artery bypass grafting±concomitant surgery between April 1999 and September 2009 including DSWI. All 13 Society for Thoracic Surgeons (STS) risk scoring variables were assessed using logistic regression in relation to developing DSWI. The STS risk scores were evaluated using the area under the receiver operating curve. A total of 44 (0.59%) patients developed DSWI. These patients had a higher mortality (9.1%) than patients without DSWI (2.6%) (P=0.03). The mean preoperative and combined STS scores were significantly higher in the DSWI patient group compared to the non-DSWI group (9.46±4.30 and 8.76±3.86 vs. 7.07±4.25 and 6.51±4.11, P=0.0003 and P=0.0005, respectively). Logistic regression identified age [odds ratio (OR)=1.055], body mass index (OR=1.076), diabetes (OR=2.00) and chronic lung disease (OR=2.47) as the significant independent determinants of DSWI from the variables considered. Mortality rates and mean STS scores are higher in patients requiring re-opening for DSWI. Not all the STS risk factors were predictors of DSWI in our population.

Failure to exclude a saccular arch aneurysm during hybrid repair: arch replacement without cerebral circulatory arrest

Thoracic endovascular aortic reconstruction (TEVAR) is increasingly used in the management of descending aortic pathology including aneurysms, dissections and transaction. When treating aortic arch pathology, hybrid procedures have been devised, in which major supra-aortic arteries are translocated using a variety of techniques. Such hybrid procedures offer an attractive alternative to open arch procedures in frail elderly patients in whom the risks of open repair are considerable. We describe a surgical bail-out procedure which was used during a hybrid aortic arch replacement when endovascular aneurysm exclusion could not be achieved.

BioGlue and Peri-strips in lung volume reduction surgery: pilot randomised controlled trial

BACKGROUND

Both tissue sealants and buttressing have been advocated to reduce alveolar air leaks from staple lines following Lung Volume Reduction Surgery (LVRS). However, the long term detrimental effects of buttressing material are increasingly apparent. We performed a pilot prospective randomised self controlled trial in patients undergoing LVRS comparing BioGlue and Peri-strips as adjuncts in preventing alveolar air-leaks.

METHODS

A pilot prospective self controlled clinical trial was conducted in patients undergoing LVRS. Each patient was treated with BioGlue on one side and pericardial buttress on the other side as an adjunct to the staple line. The sides were randomised for adjuncts with each patient acting as his own control. Duration of air leak, intercostal drainage and time to chest drain removal were the study end points.

RESULTS

10 patients undergoing the procedure were recruited between December 2005 and October 2007. There were 6 men and the mean age was 59.8 +/- 4.9 years. There was one mortality due to multi-organ failure. The BioGlue treated side had a shorter mean duration of air-leak (3.0 +/- 4.6 versus 6.5 +/- 6.9 days), lesser chest drainage volume (733 +/- 404 ml versus 1001 +/- 861) and shorter time to chest drain removal (9.7 +/- 10.6 versus 11.5 +/- 11.1 days) compared with Peri-strips.

CONCLUSION

This study demonstrates comparable efficacy of BioGlue and Peri-strips, however there is a trend favouring the BioGlue treated side in terms of reduction in air-leak, chest drainage volumes, duration of chest drainage and significant absence of complications. A larger sample size is needed to validate this result.

Massive right atrial myxoma causing exertional dyspnoea

Metastatic tumours are the commonest cardiac tumours being found in 1-3% of patients dying of cancer while primary tumours are unusual and have an incidence of 0.02-0.5%. The majority (80%) of all primary cardiac tumours are benign with myxomas accounting for 50%. Myxomas arising from the right atrium are uncommon. We present the case of a 39-year-old female with a 4-month history of progressive exertional dyspnoea accompanied by symptoms of palpitations and presyncope. Transthoracic echocardiography showed an extremely large right atrial myxoma prolapsing into the right ventricle and obstructing the tricuspid valve. We demonstrate how intraoperative transoesophageal echocardiography, prior to sternotomy, was useful in providing information about the myxoma which clearly displayed its attachment and anatomical relationship in the planning of the 'safe' surgical excision.

Use of intraventricular ribbon gauze to reduce particulate emboli during aortic valve replacement

Background

The incidence of cerebrovascular accidents following aortic valve surgery remains a devastating complication. The aim of this study was to determine the number of potential embolic material arising during aortic valve replacement and to examine the efficacy of using ribbon gauze in the left ventricle during removal of the native valve and decalcification of the aortic annulus.

Methods

Ribbon gauze was inserted into the left ventricular cavity prior to aortic valve excision in an unselected, prospectively studied series of 30 patients undergoing aortic valve replacement. A further 30 lengths of ribbon gauze were soaked in the pericardiotomy blood of the same patients and all were subjected to histological analysis.

Results

The median number of tissue fragments from the aortic valve replacement group was significantly higher than in the control group 5 (0–18) versus 0 (0–1) (p = 3.6 × 10^-5). The size of tissue fragments varied between 0.1 and 9.0 mm with a mean of 0.61 ± 1.12 mm and a median of 0.2 mm. There was a significantly higher number of tissue fragments associated with patients having surgery for aortic stenosis when compared with patients who had aortic regurgitation with median of 5 (0–18) versus 0 (0–3) (p = 0.8 × 10^-3).

Conclusion

Significant capture of particulate debris by the intraventricular ribbon gauze suggests that the technique of left ventricular ribbon gauze insertion during aortic valve excision has merit.

Mitochondrial dysfunction as the cause of the failure to precondition the diabetic human myocardium

OBJECTIVES

We have shown previously that human diabetic myocardium cannot be preconditioned. Here, we have investigated the basis of this cardioprotective deficit.

METHODS

Right atrial sections from four patient groups-non-diabetic, insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus (NIDDM) receiving glibenclamide, and NIDDM receiving metformin-were subjected to one of the following protocols: aerobic control, simulated ischemia/reoxygenation, ischemic preconditioning before ischemia, and pharmacological preconditioning with alpha 1 agonist phenylephrine, adenosine, the mito-K(ATP) channel opener diazoxide, the protein kinase C (PKC) activator phorbol-12-myristate-13-acetate (PMA), or the p38 mitogen-activated protein kinase (p38MAPK) activator anisomycin. Cellular damage was assessed using creatine kinase leakage and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) reduction. In mitochondrial preparations from non-diabetic and diabetic myocardium, mitochondrial membrane potential (Psi(m)) was assessed using JC-1 dye, and production of reactive oxygen species was determined.

RESULTS

Preconditioning with ischemia, phenylephrine, adenosine, or diazoxide failed to protect diabetic myocardium. However, activation of PKC or p38MAPK was still protective. In isolated non-diabetic mitochondria, diazoxide partially depolarized Psi(m), an effect not seen in diabetic mitochondria. Furthermore, diazoxide increased superoxide production in non-diabetic but not in diabetic mitochondria.

CONCLUSIONS

Our results show that the cardioprotective deficit in diabetic myocardium arises upstream of PKC and p38MAPK. We suggest that mitochondrial dysfunction in diabetic myocardium, possibly dysfunctional mito-K(ATP) channels, leads to impaired depolarization and superoxide production, and that this causes the inability to respond to preconditioning.

Mid-Term Results of Radial and Mammary Arteries as the Conduits of Choice for Complete Arterial Revascularization in Elective and Nonelective Coronary Bypass Surgery

OBJECTIVE

The aim of this study is to evaluate the mid-results of the use of the radial artery alongside the internal mammary artery for complete arterial revascularization in elective and nonelective coronary bypass graft surgery.

METHODS

All patients undergoing coronary artery surgery alone over a 3-year period with disease of more than one coronary artery were considered for complete arterial revascularization. Preoperatively, all patients had an Allen's test on the dominant arm and a cutoff point of 10 seconds was used. These patients were initially followed in the outpatient clinic after 6 weeks and then further followed up with the help of a mailed questionnaire. The incidence of recurrent angina and reangiogram was obtained and selected patients were further interviewed and examined in the outpatient department.

RESULTS

Over a 3-year period, 291 patients underwent total arterial revascularization using the radial and internal mammary arteries alone in Y-graft configuration. The mean age of the study population was 62.4 +/- 8.8 years, with a male to female ratio of 221 to 70. Elective surgery was performed in 230 patients (79.4%), with nonelective procedures comprising a total of 61 patients (20.6%). The mean number of distal anastomoses was 2.9 +/- 0.9. There were four perioperative mortalities (1.37%) and 43 patients (14.7%) developed low cardiac output syndrome, requiring inotropes with or without intra-aortic balloon pump. Forty patients (13.7%) developed postoperative supraventricular arrhythmias. There was no incidence of hand ischemia or wound complications. After a mean follow-up period of 35.4 +/- 6.3 months of 220 patients (75%), there was one further death and 24 patients required readmissions for cardiac-related causes. Ten patients had reangiogram for angina of which one patient had a blocked radial artery graft and two patients underwent angioplasty to their native coronary arteries. The patients' angina score was currently 0.5 +/- 1.0 versus 2.6 +/- 1.4 preoperatively.

CONCLUSION

Total arterial revascularization with the internal mammary and radial artery is associated with a low rate of perioperative complications and mortality and can be safely used in both elective and nonelective bypass graft surgery with excellent clinical results.

Coronary endarterectomy in the current era

PURPOSE OF REVIEW

The increasing incidence of diffuse coronary artery disease in the current era challenges cardiac surgeons in accomplishing their goal of complete revascularisation. Although coronary endarterectomy is used with encouraging results in most institutions, there remains some controversy in its indications, technique, and results. The purpose of this review is to highlight the important evolutions of technique in the recent past.

RECENT FINDINGS

Despite the increased risk factors and comorbidities in patients presenting with diffuse coronary artery disease requiring coronary endarterectomy, the results of coronary endarterectomy are improving inline with the improvements in the results of conventional coronary artery bypass grafting surgery. The improving results of coronary endarterectomy in the left anterior descending artery are further clarified. The intra- and postoperative use of prostacyclin has been shown to be effective in reducing mortality and perioperative myocardial infarction. The technique of open coronary endarterectomy with on-lay patch bypass grafting has been shown to be safe and effective in reducing mortality and improving patency as compared with the closed (traction) method of coronary endarterectomy. The use of coronary endarterectomy was also found to be effective in the treatment of in-stent restenosis in the setting of diffuse coronary artery disease. The results of off-pump coronary endarterectomy are encouraging and comparable with the conventional coronary endarterectomy using cardiopulmonary bypass.

SUMMARY

With the increasing incidence of diffuse coronary artery disease and improving results of coronary endarterectomy, it is vital for cardiac surgeons to have coronary endarterectomy in their armamentarium to achieve complete coronary revascularisation.

The effect of gliclazide and glibenclamide on preconditioning of the human myocardium

The cardioprotection of ischaemic preconditioning may be abolished in diabetic patients especially when some oral hypoglycaemics are used. The dose-response effect of gliclazide and glibenclamide on ischaemic preconditioning and the action of glibenclamide on signal transduction in human myocardium were investigated using right atrial appendages from cardiac surgery patients. Glibenclamide (0.1, 1, 3 and 10 microM) and gliclazide (1, 10, 30 and 100 microM) were added for 10 min prior to ischaemic preconditioning. The cardioprotection was abolished by glibenclamide at all concentrations and by gliclazide at supratherapeutic concentrations of 30 and 100 microM. Glibenclamide abolished the protective effect of mitoK(ATP) channel opening but not that of protein kinase C (PKC) or p38 mitogen activated protein kinase (p38MAPK) activation. In conclusion, glibenclamide and gliclazide differential effects may be a result of differential sensitivities. Glibenclamide does not block protection conferred by either PKC or p38MAPK activation. These findings may have clinical implications in ischaemic heart disease.

Coronary endarterectomy: impact on morbidity and mortality when combined with coronary artery bypass surgery

BACKGROUND

The results of coronary endarterectomy (CE) performed in addition to coronary artery bypass grafting (CABG) have been controversial. We aimed to examine the impact of CE performed in addition to CABG when compared with CABG alone in our unit.

METHODS

Patients who had CABG between January 1995 and December 2001 were included. They were divided into two groups, the CABG-only group and CABG and CE group. The following outcomes were compared: perioperative myocardial infarction, postoperative ventricular arrhythmias, cerebrovascular accident, renal impairment, and early mortality.

RESULTS

Of 5,782 patients who underwent CABG, 461 patients (8.6%) required CE in addition to CABG. There was a higher mortality and incidence of postoperative renal impairment in the group of patients who had CABG and CE, with no significant difference in other outcomes. However, the patients in the CABG and CE group had a higher incidence of male sex, previous myocardial infarctions, preoperative renal impairment, and poor left ventricular function, with longer cross-clamp and cardiopulmonary bypass times than in the CABG-only patients. Although female sex, renal impairment, nonelective surgery, impaired left ventricular function, and peripheral vascular disease were associated with increased mortality in all the patients, and use of statins and aspirin was associated with a reduction in mortality, CE was not a predictor of mortality. Furthermore, on propensity scores analysis, CE was not associated with increased mortality.

CONCLUSIONS

Coronary endarterectomy when combined with CABG seemed to be associated with a higher mortality than isolated CABG in our study groups, but this is related to comorbidities of these patients rather than the CE.

Use of Saphenous Vein Graft in Axillary Artery Cannulation

Axillary artery cannulation for cardiopulmonary bypass is becoming increasingly used for surgery of aortic dissections for reoperations and extensively diseased ascending aortas. This can be achieved either directly or with a graft. We describe a case with a repair of chronic type A dissection in which axillary cannulation was achieved by placing the arterial cannula into a saphenous vein graft that had been anastomosed end-to-side to the axillary artery. This provides a natural, inexpensive, readily available, and more hemostatic alternative to the use of prosthetic grafts.

Efficacy of transmyocardial laser revascularization and thoracic sympathectomy for the treatment of refractory angina

BACKGROUND

Transmyocardial laser revascularization (TMR) is an effective treatment for relief of refractory angina. This benefit may be mediated by increase in myocardial perfusion or by cardiac denervation. We investigate the efficacy of TMR and thoracic sympathectomy (TS) for relief of angina and whether any clinical benefit is associated with enhanced myocardial perfusion.

METHODS

Twenty consecutive patients with nonrevascularizable coronary arteries and intractable angina were prospectively randomized to have TMR by holmium: yttrium aluminum garnet laser or TS. Subjects were clinically evaluated before, and for 42 months after, surgery. They underwent exercise tolerance testing and rest and stress quantitative perfusion magnetic resonance imaging (MRI) before, and 6 months after surgery.

RESULTS

The demographics of the two groups were similar. There was no perioperative mortality; however, two patients died in the TS group during follow-up. The Canadian Cardiovascular Society angina score improved from 3.4 +/- 0.5 to 2.6 +/- 1.1 (p = 0.06) in the TS group at 6 months but returned to 3.2 +/- 0.7 at 42 months, while in the TMR group it improved from 3.6 +/- 0.5 to 1.9 +/- 0.7 (p = 0.008) at 6 months and deteriorated to 2.5 +/- 0.9 (p = 0.01) after 42 months of surgery. The TMR-treated patients showed significant improvements in the SF-36 scores and Seattle Angina Questionnaire only at 6 months, whereas TS-treated patients did not show amelioration at any time during follow-up. The MRI protocol was completed in 15 of 20 (TMR = 8; TS = 7) patients and no significant differences in qualitative or quantitative perfusion variables were demonstrated in either group.

CONCLUSIONS

A greater clinical benefit was obtained with TMR than with TS early after surgery but this clinical effect did not seem to be associated with improvement in myocardial perfusion as assessed by MRI and part of the beneficial effect was lost by 42 months after surgery.

Delayed preconditioning of the human myocardium: signal transduction and clinical implications

OBJECTIVE

Ischemic preconditioning confers cardioprotection in early and delayed phases. We investigated the delayed window of pharmacological and ischemic preconditioning in human myocardium, and the involvement of mitoKATP, PKC and p38MAPK.

METHODS

These studies were carried out using human right atrial tissue in a cell necrosis model. The tissue was obtained from patients undergoing coronary artery surgery.

RESULTS

The second window triggered by ischemia, phenylephrine or adenosine resulted in similar cardioprotection between 24 and 72 h following the intervention. Atrial tissue taken from patients with a single episode of angina between 24 and 72 h prior to surgery were already protected and preconditioning with ischemia, phenylephrine or adenosine did not add to the protection. The trigger of preconditioning with mitoKATP channel opener diazoxide, PKC activator PMA and p38MAPK activator anisomycin produced similar delayed protection to that of ischemia or phenylephrine. Cardioprotection was lost when mitoKATP channels were blocked by 5HD, PKC by chelerythrine and p38MAPK by SB203580 24 h after the trigger of preconditioning.

CONCLUSIONS

Ischemic and pharmacological preconditioning induce similar delayed cardioprotection of the human heart. This second window of protection that is seen between 24 and 72 h occurs in vitro and in vivo and requires opening of mitoKATP channels and activation of PKC and p38MAPK.

Does the type of prosthesis influence early left ventricular mass regression after aortic valve replacement? Assessment with magnetic resonance imaging

BACKGROUND

Debate exists regarding selection of the prosthesis type most likely to maximize early left ventricular (LV) mass regression after aortic valve replacement (AVR) for stenotic valvular disease. The aim of this study was to compare the degree of LV mass regression measured by MRI 6 months after prospectively randomized valve implantation for two biological prostheses, stented and stentless, and for two mechanical valves, tilting disc and bileaflet.

METHODS

Thirty-nine consecutive patients with predominant aortic stenosis accepted for elective AVR were studied. Twenty patients requiring a tissue prosthesis were randomly assigned to receive either a Freestyle or Mosaic valve. The remaining 19 patients in whom mechanical prosthesis was indicated were randomly assigned to receive either an Ultracor or an ATS valve.

RESULTS

There was no difference in valve size implanted between the compared groups. LV mass measurements were performed with MRI (1.5-T Vision, Siemens, Germany) immediately before and 6 months after surgery. All valve types produced significant postoperative reduction in LV mass compared with preoperative values (P <.01). Percent change in LV mass regression was similar between the two porcine valve types, Mosaic (24.4% +/- 11.1%) and Freestyle (21.1% +/- 16.7%), and between the two mechanical valve designs, Ultracor (19.3% +/- 9.5%) and ATS (26.3% +/- 10.8%), respectively.

CONCLUSIONS

Significant LV remodeling occurs early after AVR for aortic stenosis. The degree of regression in LV mass is independent of prosthesis type implanted.

Mid-term results of combined transmyocardial laser revascularization and coronary artery bypass

BACKGROUND

Transmyocardial laser revascularization is increasingly used to treat intractable angina in the absence of graftable vessels; however, its role in combination with coronary artery bypass grafting remains undefined. The aim of this pilot study was to investigate the outcome of the combination therapy at mid-term follow-up.

METHODS

Patients (n = 20) who had elective coronary artery bypass with one or more nongraftable coronary arteries were prospectively randomized to have either coronary artery bypass grafting alone or combination coronary artery bypass grafting plus transmyocardial laser revascularization with a holmium:YAG (yttrium-aluminum-garnet) laser to nongraftable areas. All patients had an exercise tolerance test preoperatively and at 6, 18, and 36 months follow-up. Stress echocardiography was performed on 17 patients at 18 months postoperatively, and regional wall motion score index was calculated in lased and nonlased nonrevascularizable myocardium of the left ventricle at rest and with dobutamine stress.

RESULTS

Both groups of patients were similar in preoperative demographics and operative data. There was no perioperative death. There was no difference between the two groups in angina scoring at 6, 18, and 36 months follow-up. Exercise tolerance improved by a mean of 46.8 +/- 20.0 seconds in the coronary artery bypass grafting group versus 199.2 +/- 66.5 seconds per patient in the coronary artery bypass grafting plus transmyocardial laser revascularization group (p = 1.8 x10(-6)) at 6 months; this benefit was maintained at 18 months (157 +/- 46.3 versus 61 +/- 39.2 seconds; p = 4 x10(-4)) but was lost at 36 months (57.2. +/- 42.1 versus 68.1 +/- 46.7 seconds; p = 0.70). The mean values for wall motion score index in the lased and nonlased regions at each stage of dobutamine stress at 18 months after surgery were not statistically significant.

CONCLUSIONS

The combination of coronary artery bypass and transmyocardial laser revascularization improved exercise tolerance in patients in whom complete revascularization could not be achieved by bypass grafting alone in the short term, but this benefit was lost by 36 months postoperatively. The transient improvement in exercise tolerance cannot be explained by changes in contractility in the lased areas.

Surgical approach for pericardiectomy: a comparative study between median sternotomy and left anterolateral thoracotomy

Pericardiectomy is the definitive treatment for constrictive pericarditis but the best surgical approach remains controversial. In this study we compared the results of pericardiectomy performed on 36 patients with constrictive pericarditis between 1995 and 2001. Pericardiectomy was performed by median sternotomy in 15 patients and by left anterolateral thoracotomy in 21 patients. All patients were reviewed at 6 weeks post operatively. Both groups of patients were similar in age, sex distribution, NYHA shortness of breath status, aetiology, presenting symptoms and duration of symptoms. Mortality was similar in the two groups with three deaths (14.2%) in the thoracotomy group and two deaths (13.3%) in the median sternotomy group. NYHA status improved in both thoracotomy (3.0+/-0.8 to 1.6+/-0.7; P=3.3x10(-6)) and median sternotomy (2.9+/-0.7 to 1.5+/-0.6; P=2.8x10(-5)) groups. The degree of improvement was not significant between the two groups (P=0.63). In addition ionotropic support and postoperative hospital stay were similar between the two groups. There was a higher incidence of wound infections (23.8 versus 6.6%; P=0.13) and pulmonary complications (23.8 versus 13.3%; P=0.33) associated with thoracotomy. In conclusion pericardiectomy improves NYHA status in all patients and mortality rates are similar in both the approaches.

The aging human myocardium: tolerance to ischemia and responsiveness to ischemic preconditioning

BACKGROUND

Increasing age has been recognized as a cause for adverse prognosis in the setting of myocardial infarction, coronary angioplasty, and cardiac surgery. This is attributed to a greater susceptibility of the senescent heart to ischemic injury and to a lower response to protective interventions. This study investigated the effect of aging on the tolerance to ischemia of the human myocardium and its response to ischemic preconditioning.

METHODS

Right atrial specimens from 128 patients undergoing elective heart surgery were collected, sliced, and equilibrated for 30 minutes before being randomized into 3 study protocols: (1) 210 minutes of aerobic incubation (time-matched control), (2) 90 minutes of simulated ischemia and 120 minutes of reoxygenation, and (3) ischemic preconditioning with 5 minutes of ischemia and 5 minutes of reoxygenation before 90 minutes of ischemia and 120 minutes of reoxygenation. Patients were subdivided into 3 age groups: 30 to 49 years, 50 to 69 years, and 70 to 90 years. At the end of each protocol, tissue injury and viability were assessed by the leakage of creatine kinase and the reduction of 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide to insoluble formazan dye.

RESULTS

There were no differences among the 3 groups of patients in their comorbid conditions or their cardiac medications. Ischemic injury was similar in all 3 groups (creatine kinase = 4.1 +/- 0.7, 3.6 +/- 1.0, and 4.3 +/- 1.1 U/g wet weight, respectively; 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide = 64.7 +/- 31.3, 96.3 +/- 32.0, and 61.0 +/- 30.4 mM/g wet weight, respectively, P = not significant in all cases), and ischemic preconditioning equally protected against ischemia at all ages (creatine kinase = 1.9 +/- 0.5, 1.8 +/- 0.4, and 2.1 +/- 0.6 U/g wet weight, respectively; 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide = 157.9 +/- 31.5, 170.7 +/- 35.3, and 138.4 +/- 43.8 mM/g wet weight, respectively; P <.05 in all cases vs ischemia alone).

CONCLUSION

Age does not influence the tolerance of the human myocardium to ischemia or the protective effect of ischemic preconditioning. These results indicate the need for a reevaluation of the importance of age in risk scoring in cardiac surgery.

Long-term administration of nicorandil abolishes ischemic and pharmacologic preconditioning of the human myocardium: role of mitochondrial adenosine triphosphate-dependent potassium channels

BACKGROUND

Acute administration of mitochondrial adenosine triphosphate-dependent potassium channel openers preconditions the heart, but whether their long-term administration induces a permanent state of protection is unknown. These studies investigate the effect of long-term treatment with the mitochondrial adenosine triphosphate-dependent potassium channel opener nicorandil on the response of the human myocardium to ischemia and preconditioning.

METHODS

Right atrial tissue obtained from patients regularly treated with or without nicorandil (mean of 20 mg/d for 18.6 +/- 2.5 months) and undergoing cardiac surgery was sliced and equilibrated for 30 minutes and then subjected to 90 minutes of simulated ischemia, followed by 120 minutes of reoxygenation. In study 1 the following groups were studied to investigate the effect of nicorandil on the susceptibility of the myocardium to ischemia and on the protective effect of ischemic and pharmacologic preconditioning: (1) aerobic control; (2) simulated ischemia and reoxygenation alone; (3) ischemic preconditioning with 5 minutes of simulated ischemia and 5 minutes of reoxygenation; and (4) phenylephrine (0.1 micromol/L) for 5 minutes and 5 minutes' washout before simulated ischemia and reoxygenation. In study 2 the following groups were studied to investigate the effect of nicorandil on the responsiveness of mitochondrial adenosine triphosphate-dependent potassium channels: (1) aerobic control; (2) simulated ischemia and reoxygenation; (3) ischemic preconditioning; (4) diazoxide (100 micromol/L) for 10 minutes before simulated ischemia and reoxygenation, and (5) 5-hydroxydecanoate (1 mmol/L) for 10 minutes before simulated ischemia and reoxygenation. In study 3 the following groups were included to investigate the effect of the long-term administration of nicorandil on the kinase pathway involved in preconditioning: (1) aerobic control; (2) simulated ischemia and reoxygenation alone; (3) ischemic preconditioning; (4) phorbol 12-myristate 13-acetate (1 micromol/L), a protein kinase C activator, for 10 minutes before simulated ischemia and reoxygenation; and (5) anisomycin (1 nmol/L), a p38 mitogen-activated protein kinase activator, for 10 minutes before simulated ischemia and reoxygenation. At the end of each protocol, the leakage of creatine kinase (in units per gram wet weight) and the reduction of 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide into insoluble formazan dye (in millimoles per gram wet weight) were measured.

RESULTS

In study 1 the leakage of creatine kinase and the reduction of 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide induced by simulated ischemia and reoxygenation were similar in the groups with or without nicorandil (creatine kinase, 3.4 +/- 0.1 and 3.5 +/- 0.2, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 74.6 +/- 3.9 and 67.9 +/- 7.3, respectively; P >.2 in each instance). Ischemic preconditioning and pharmacologic preconditioning protected the myocardium from patients without nicorandil (creatine kinase, 2.3 +/- 0.1 and 2.4 +/- 0.1, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 131.4 +/- 4.9 and 128.4 +/- 5.6, respectively; P < 0.001 vs simulated ischemia and reoxygenation alone in each instance) but not the myocardium from patients receiving nicorandil (creatine kinase, 3.3 +/- 0.1 and 3.3 +/- 0.2, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 89.7 +/- 6.5 and 86.4 +/- 5.2, respectively; P >.2 vs simulated ischemia and reoxygenation alone in each instance). In study 2 the administration of diazoxide had identical protection to that of ischemic preconditioning in the myocardium of patients not receiving nicorandil (creatine kinase, 2.1 +/- 0.2 and 2.3 +/- 0.1, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 141.4 +/- 7.4 and 131.4 +/- 4.9, respectively; P < 0.001 vs simulated ischemia and reoxygenation alone in each instance) but failed to precondition the myocardium from patients treated with nicorandil (creatine kinase, 3.3 +/- 0.2 and 3.4 +/- 0.1, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 90.1 +/- 7.2 and 86.4 +/- 5.2, respectively; P > 0.2 vs simulated ischemia and reoxygenation alone in each instance). In study 3 phorbol 12-myristate 13-acetate or anisomycin given for 10 minutes before simulated ischemia and reoxygenation afforded similar protection to that of ischemic preconditioning in the myocardium from patients with (creatine kinase, 1.5 +/- 0.3 and 1.4 +/- 0.1, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 147.0 +/- 4.9 and 160.0 +/- 16.1, respectively; P < 0.001 vs simulated ischemia and reoxygenation alone in each instance) and without nicorandil (creatine kinase, 1.7 +/- 0.4 and 1.4 +/- 0.2, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 160.3 +/- 13.6 and 158.3 +/- 11.8, respectively; P <.001 vs simulated ischemia and reoxygenation alone in each instance).

CONCLUSION

The myocardium of patients chronically treated with nicorandil cannot be preconditioned either by ischemia or pharmacologically, and this is because of unresponsive mitochondrial adenosine triphosphate-dependent potassium channels. However, protection can be obtained by protein kinase C and p38 mitogen-activated protein kinase activation, which are downstream of mitochondrial adenosine triphosphate-dependent potassium channels in the signaling transduction pathway of preconditioning.

Use of the intra-aortic balloon pump for dilatation of benign tracheobronchial strictures

Tracheobronchial benign stenoses may cause life-threatening emergencies. Here, we will describe a novel technique for the management of tracheal and bronchial stenoses using an intra-aortic balloon pump. The intra-aortic balloon pump was used for dilatation of a postoperative tracheal stricture in a 43-year-old man and a bronchial stricture in a 29-year-old woman with Wegener's granulematosis. There were no intraoperative or postoperative complications in either patient, and the stenosis was relieved successfully in each patient. The intra-aortic balloon pump can be used safely and effectively for the management of difficult tracheobronchial strictures.

Pharmacological and ischemic preconditioning of the human myocardium: mitoK(ATP) channels are upstream and p38MAPK is downstream of PKC

BACKGROUND

These studies investigate the role of mitoK(ATP) channels, protein kinase C (PKC) and Mitogen activated protein kinase (p38MAPK) on the cardioprotection of ischemic (IP) and pharmacological preconditioning (PP) of the human myocardium and their sequence of activation.

RESULTS

Right atrial appendages from patients undergoing elective cardiac surgery were equilibrated for 30 min and then subjected to 90 min of simulated ischemia followed by 120 min reoxygenation. At the end of each protocol creatinine kinase leakage (CK U/g wet wt) and the reduction of MTT to formazan dye (mM/g wet wt) were measured. Similar protection was obtained with alpha1 agonist phenylephrine, adenosine and IP and their combination did not afford additional cardioprotection. Blockade of mitoK(ATP) channels with 5-hydroxydecanoate, PKC with chelerythrine, or p38MAPK with SB203580 abolished the protection of IP and of PP. In additional studies, the stimulation of mitoK(ATP) channels with diazoxide or activation of PKC with PMA or p38MAPK with anisomycin induced identical protection to that of IP and PP. The protection induced by diazoxide was abolished by blockade of PKC and by blockade of p38MAPK. Furthermore, the protection induced by PMA was abolished by SB203580 but not by 5-hydroxydecanoate, whereas the protection induced by anisomycin was unaffected by either 5-hydroxydecanoate or chelerythrine.

CONCLUSIONS

Opening of mitoK(ATP) channels and activation of PKC and p38MAPK are obligatory steps in the signal transduction cascade of IP and PP of the human myocardium with PKC activation being downstream of the opening of mitoK(ATP) channels and upstream of p38MAPK activation.

Oesophageal strictures: new indication for intra-aortic balloon pumps?

Oesophageal strictures regardless of aetiology are a difficult and challenging problem facing the oesophageal surgeon. Various methods and techniques have been described and are routinely used in clinical practice with varying rates of efficacy and complications. We describe here a novel graded atraumatic technique for the management of oesophageal strictures using intra-aortic balloon pumps.

Pituitary gland macroadenoma: a cause of transient blindness after cardiac surgery

Pituitary gland macroadenoma complicating cardiac surgery is an uncommon condition of spectacular clinical presentation that is generally treated by surgery. We report here on an unusual presentation of this condition that was successfully managed by medical treatment.

alpha1-Adrenoceptors during simulated ischemia and reoxygenation of the human myocardium: effect of the dose and time of administration

OBJECTIVE

We sought to investigate the effect of alpha1-adrenoceptor activity on the ischemic and reoxygenated human myocardium.

METHODS

Right atrial appendages (n = 6 per group) obtained during elective cardiac operations were sliced and stabilized in normoxic normothermic buffer solution for 30 minutes and then subjected to 90 minutes of simulated ischemia, followed by 120 minutes of reoxygenation. In study 1 the dose responses to the alpha1-adrenoceptor agonist phenylephrine (0.01, 0.1, 1, 10, and 100 micromol/L) and to the alpha1-adrenoceptor antagonist prazosin (0.1, 1, 10, and 100 micromol/L) when administered for 10 minutes before ischemia, during ischemia, and during reoxygenation were examined. The influence of the time of administration (ie, before ischemia, during ischemia, or during reoxygenation) of phenylephrine (0.1 micromol/L) and prazosin (10 micromol/L) was then investigated in study 2. In study 3 the effect of the combined administration of phenylephrine given before ischemia and prazosin given during ischemia was investigated. In study 4 the protective effect of phenylephrine given before ischemia (for 10 minutes or for 5 minutes with a 5-minute washout period) was compared with that of ischemic preconditioning (5 minutes of ischemia and 5 minutes of reoxygenation). At the end of each protocol, the leakage of creatine kinase (in units per gram of wet weight) and the reduction of 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide to insoluble formazan dye (in millimoles per gram of wet weight) were measured.

RESULTS

Phenylephrine is maximally beneficial at 0.1 and 1 micromol/L (creatinine kinase, 0.97 +/- 0.06 and 0.95 +/- 0.03 U/g, respectively; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 153.0 +/- 7.8 and 156.2 +/- 6.7 mmol/g, respectively) compared with ischemic control (creatine kinase, 1.87 +/- 0.03 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 108.5 +/- 6.8 mmol/g; P <.05) but prazosin is detrimental at concentrations above 10 micromol/L (creatine kinase, 5.22 +/- 0.29 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 69.8 +/- 2.9 mmol/g; P <.05 vs ischemic control). In addition, phenylephrine (0.1 micromol/L) is protective when given before ischemia (creatine kinase, 2.06 +/- 0.21 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 148.5 +/- 4.5 mmol/g; P <.05 vs ischemic control) but is detrimental when given during ischemia alone (creatine kinase, 4.49 +/- 0.98 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 70.5 +/- 6.1 mmol/g; P <.05 vs ischemic control) and has no significant effect during reoxygenation. In contrast, prazosin (10 micromol/L) is beneficial when given during ischemia alone (creatine kinase, 1.34 +/- 0.10 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 148.5 +/- 4.5 mmol/g; P <.05 vs ischemic control), is detrimental when given during reoxygenation alone (creatine kinase, 1.5 +/- 0.16 U/g; 3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, 85.0 +/- 4.7 mmol/g; P <.05 vs ischemic control), and has no effect when given before ischemia. The use of phenylephrine before ischemia alone is as protective as prazosin given during ischemia alone, but the combination of the two drugs does not cause additional benefit. Interestingly, the protection afforded by phenylephrine when given before ischemia is similar to that obtained with ischemic preconditioning.

CONCLUSIONS

In the human myocardium activation of alpha1-adrenoceptors before ischemia is protective but is detrimental during ischemia, whereas blockade of alpha1-adrenoceptors is beneficial during ischemia but detrimental during reoxygenation. The degree of protection achieved by activation of the alpha1-adrenoceptors before ischemia is similar to that obtained with blockade of alpha1-adrenoceptors during ischemia and that of ischemic preconditioning.

Plasma aluminum levels during sucralfate prophylaxis for stress ulceration in critically ill patients on continuous venovenous hemofiltration: a randomized, controlled trial

OBJECTIVE

To investigate plasma aluminum levels in critically ill patients requiring continuous venovenous hemofiltration (CVVH), while receiving sucralfate for stress ulcer prophylaxis.

DESIGN

Randomized, controlled study.

SETTING

Cardiothoracic intensive care unit.

PATIENTS

Twenty postoperative cardiac surgical patients

INTERVENTIONS

Twenty patients requiring CVVH support for acute renal failure were randomized into two groups for concurrent stress ulcer prophylaxis. Group 1 (n = 10) received nasogastric sucralfate, and group 2 patients received intravenous ranitidine. Plasma aluminum samples were analyzed at baseline and on days 1, 4, 8, and 14.

MEASUREMENTS AND MAIN RESULTS

In both the sucralfate and ranitidine groups, clinical characteristics, number of days the patients were on CVVH support (median, 5.5 [range, 2-32] days, and median, 3 [range, 2-18] days, respectively) and duration of prophylaxis (median, 12 [range, 4-42] days, and median, 16 [range, 3-62] days, respectively) were similar. There were no significant differences in the baseline aluminum concentrations (median, 0.37 [range, 0.15-1.63] micromol/L, vs. median, 0.32 [range, 0.11-1.0] micromol/L; p =.79). On initiation of therapy, aluminum levels in the sucralfate group increased dramatically on day 1 (median, 0.87 [range, 0.26-4.4] micromol/L) and peaked on day 4 (median, 2.84 [range, 1.52-4.44] micromol/L) with seven of the ten patients exhibiting levels of >2 micromol/L. In the ranitidine group, there were no significant elevations in aluminum levels above baseline. Analysis of the two groups at the four time points revealed that aluminum levels in the sucralfate group were up to 14 times higher, with the confidence intervals suggesting that the true value may be 2-27 times higher (p <.0001). On cessation of CVVH, a rapid decline in aluminum levels was observed. No clinical manifestations of these potentially toxic levels were observed.

CONCLUSIONS

The use of sucralfate for stress ulcer prophylaxis in patients requiring CVVH results in toxic elevations in plasma aluminum levels. Alternative agents should be considered for prophylaxis in these patients.

Video assisted thoracoscopic bullectomy and acromycin pleurodesis: an effective treatment for spontaneous pneumothorax

The introduction of video assisted thoracoscopic surgery (VATS) has led to the development of several endoscopic options for the management of spontaneous pneumothorax. We describe here our experience in the management of primary spontaneous pneumothorax (SP). We carried out 58 VATS procedures on 55 patients during the period 1993-95. There were six conversions to open thoracotomy because of dense adhesions in five patients and a large apical bulla of 20 cm in one. These patients were excluded from the study. The remaining 49 patients underwent 52 VATS procedures. There were 37 males and 12 females with a median age of 23 (range: 15-71) years. The indications for surgery were persistent SP for more than 5 days in 21 (40%), and recurrent SP in 31 (60%). Twenty-six procedures (25 patients) consisted of bullectomy alone (group 1; 1/1/93-30/9/94) and the next 26 procedures (24 patients) included chemical pleurodesis with 2 g of Acromycin (Lederle) in 10 ml of 0.9 normal saline (group 2; 1/10/94-31/12/95). Both groups had a mean follow up of 38 months (range: 36-40). Mean postoperative chest drainage in group 2 (3.1 +/- 1.09) was significantly shorter than in group 1 (4.7 +/- 1.0). Group 2 patients also had a shorter hospital stay (4.8 /- 1.08 vs. 6.76 +/- 1.09). There were five (20%) recurrences in group 1 while only one (4%) occurred in group 2. In view of these results we recommend the routine use of Acromycin pleurodesis in addition to thoracoscopic bullectomy.

Residual atrial fibrillation and clinical consequences following postoperative supraventricular arrhythmias

AIMS

This retrospective study investigated whether the supraventricular arrhythmias (SVA) observed during cardiac surgery are limited to or persist beyond the postoperative period, their clinical consequences and whether they are influenced by preoperative and postoperative factors.

METHODS

A total of 375 patients undergoing elective bypass graft surgery over a 15-month period by three surgeons were included. All patients had their preoperative medications continued to the day of surgery and prophylactic anti-arrhythmic medications were not used in any of the cases. Standard anaesthetic techniques were used. Rhythm disturbances were diagnosed by ECG. The arrhythmias were treated medically or by cardioversion. All patients were followed up for 6 months.

RESULTS

Postoperative SVA occurred in 25% of patients. The commonest arrhythmia was atrial fibrillation (89.4%), followed by atrial flutter (6.4%) and supraventricular tachycardia (4.2%). In 89. 8% of the cases, the arrhythmias occurred within the first four postoperative days with a maximum incidence on the second day (27. 7%). Atrial fibrillation was still present in 50% of patients at hospital discharge and in 39% at 6 months follow up. Patients with arrhythmias had a prolonged hospital stay (7.7+/-2.6 vs. 6.0+/-2.6 days; P<0.05). There was no hospital mortality in the study and the incidence of postoperative stroke was equal in the sinus rhythm and arrhythmia patients (1.1%). SVA were more frequent when cardioplegia was used to protect the heart (32%) than with intermittent ischaemia (9%; P<0.001). At 6 months follow up, the patients receiving cardioplegia also had a higher prevalence of atrial fibrillation than those operated with intermittent ischaemia (41% vs. 22%; P<0. 05). The incidence of SVA and persistence of atrial fibrillation was unrelated to other preoperative and intraoperative factors.

CONCLUSION

Postoperative supraventricular arrhythmias have a long-lasting effect on cardiac rhythm: patients with SVA have a high probability of remaining in atrial fibrillation at hospital discharge and 6 months after surgery. The occurrence of atrial fibrillation seems to be influenced by the type of myocardial protection used but this does not appear to exert harmful effects.

Early discharge following coronary bypass surgery: is it safe?

OBJECTIVES

Early discharge has been proposed as a means of containing the escalating cost of health care in cardiac surgery. The aim of this study was to investigate whether shortening the length of hospital stay after coronary artery bypass surgery is safe and cost effective.

METHODS

Patients (n=198) undergoing elective bypass surgery by two surgeons for a period of 12 months were prospectively entered into the study but not randomized. The anaesthetic and surgical treatments were identical in all patients with the exception that one of the surgeons used intermittent cold crystalloid cardioplegia ('normal discharge' group; n=119) and the other used intermittent ischaemia without cardioplegia ('early discharge' group; n=79). Previous to the study both surgeons discharged patients on the 7th-8th postoperative day. For the present study, one of the two surgeons adopted the new policy of discharging patients on the 4th postoperative day ('early discharge' group). The criteria for hospital discharge included: presence of sinus rhythm, absence of pyrexia and wound infection, normal routine blood tests, satisfactory chest X-ray and ECG and full mobility.

RESULTS

The clinical characteristics were identical in the two groups. The number of grafts per patient was 2.8+/-0.8 and 3.2+/-1.0, and the total ischaemic time 47+/-13 and 46+/-14 min in the normal and early discharge groups, respectively (P=NS in each instance). In the normal discharge group the mean hospital stay was 7.7+/-3.3 days whereas in the early discharge group it was 4.7+/-2.0 days (P<0. 0001) with 73.5% of the patients being discharged within the first 4 days following surgery. The shortening of hospital stay resulted in a mean reduction of costs of pound750/patient. There was no operative mortality (<30 days following surgery) and the incidence of non-fatal perioperative complications were similar in the two groups, with the exception that the incidence of supraventricular arrhythmias was significantly higher in the normal discharge group than in the early discharge group (33% vs. 6.3% respectively; P<0. 0001). These rhythm abnormalities occurred within the first 4 days in 89% of patients following surgery and were the cause of readmission in only one patient in the normal discharge group. There were a total of ten (8.4%) readmissions in the normal discharge group and three (3.8%) in the early discharge group.

CONCLUSION

Shortening the postoperative hospital stay to 4 days following elective coronary bypass surgery appears to be safe and can be a means of reducing the cost of care. This in turn may result in a greater availability of resources and in an effective way of reducing waiting lists.