Comparison of epicardial and body surface ECG potentials in man.

Simultaneously measured epicardial electrograms and body surface electrocardiograms in human subjects were compared. Unipolar electrograms were recorded from up to three epicardial sites in each of 21 patients one week after aortocoronary bypass surgery. Simultaneously, electrocardiograms were recorded from 37 body surface electrodes. The epicardial electrograms from ventricular sites correlated well during the QRS complex with body surface electrocardiograms at geometrically similar positions. In particular, most posterior epicardial sites correlated best with posterior body surface regions, contrary to model predictions. P waves recorded from the right atrial surface showed a sharp negative deflection not evident in body surface P waves. A large intersubject variation was evident when the magnitude of epicardial potentials was compared with the body surface potentials. The findings are relevant to the interpretation of surface maps, the estimation of epicardial potentials from surface maps, and the positioning of body surface electrodes.

Usefulness of Holter monitoring to improve the sensitivity of exercise testing in determining the degree of myocardial revascularization after coronary artery bypass grafting for stable angina pectoris.

To assess whether Holter monitoring improves the sensitivity of exercise testing in identifying incomplete myocardial revascularization, both tests were performed in 45 patients from 3 to 5 months after elective coronary artery bypass grafting (CABG) for stable angina pectoris. Coronary angiography revealed incomplete revascularization in 26 patients. Six of these 26 had 52 episodes of ST-segment depression during Holter monitoring and myocardial ischemia during exercise testing. Their exercise capacity was significantly lower than that of 10 other patients in whom the results of exercise testing only were positive (heart rate at 0.1 mV ST-segment depression 112 +/- 9 vs 123 +/- 15 beats/min, p less than 0.001). In the other 10 patients with incomplete myocardial revascularization the results of both investigations were negative. The graft patency rate was lower in patients with a positive response to exercise testing than in those with a negative response (52% vs 71%, p less than 0.005). Myocardial revascularization was angiographically complete in 19 patients. In 18 of these 19 patients the findings of both investigations were negative; in 1 patient Holter monitoring revealed episodes of ST-segment elevation suggestive of variant angina. Thus, after CABG for stable angina pectoris the results of Holter monitoring do not improve the sensitivity of exercise testing in identifying patients with angiographically incomplete myocardial revascularization because findings are positive only in patients with low exercise capacity. Both tests fail to show evidence of myocardial ischemia in most patients with angiographically complete myocardial revascularization.

Chlamydia pneumoniae in infrequently examined blood vessels.

AIM: To determine the prevalence of Chlamydia pneumoniae DNA in infrequently examined blood vessels. METHODS: Vessels obtained from 15 men and six women at coronary artery bypass surgery were tested by a nested polymerase chain reaction (PCR) assay for C pneumoniae DNA. RESULTS: Chlamydia pneumoniae DNA was detected in four of six atheromatous ascending aorta specimens but in none of eight non-atheromatous aorta specimens, in six of 11 atheromatous internal mammary artery specimens but in none of seven non-atheromatous internal mammary artery specimens, in five of seven long saphenous vein specimens showing evidence of disease but in none of 12 specimens without evidence of disease, and in two of three previously grafted veins. Overall, C pneumoniae occurred significantly more often in diseased than in normal vessels (p = < 0.00001). CONCLUSIONS: Chlamydia pneumoniae is often present in diseased areas of arteries, including the internal mammary arteries, and even in diseased areas of veins. It is not present in apparently healthy areas of either type of vessel.

Minimally invasive coronary revascularization through parasternal incisions without cardiopulmonary bypass.

BACKGROUND: We report the results of minimally invasive coronary revascularization without cardiopulmonary bypass through miniparasternal incisions. METHODS: This procedure was performed in 40 patients with disease in the left anterior descending, first diagonal, and right coronary arteries. After a 5- to 7-cm left vertical parasternal incision and removal of two costal cartilages, the left internal mammary artery was harvested up to the 2nd rib. The left anterior descending artery was occluded by means of two polydioxanone monofilament sutures. The anastomosis was performed with one 7-0 Prolene suture while the heart was beating. In 4 cases the left internal mammary artery was used as a sequential graft to the left anterior descending artery and the first diagonal artery. In 14 cases the right coronary artery was grafted with the right internal mammary artery through a right parasternal incision. Postoperatively, 95% of the patients underwent angiographic assessment of the anastomoses. RESULTS: We performed 52 anastomoses (34 to the left anterior descending artery, 4 to the first diagonal artery, and 14 to the right coronary artery). The mortality was 0% and the morbidity included postoperative bleeding (5%), acute renal failure (2.5%), atrial fibrillation (2.5%), and wound infection (5%). No patient had ventricular arrhythmias or circulatory problems during or after the operation. Two patients (5%) with right internal mammary artery-to-right coronary artery grafting had graft failure that required a redo operation. CONCLUSIONS: Small vertical parasternal incisions may be an alternative approach for single and multiple coronary revascularization, with a low incidence of intraoperative cardiac complications. The application of this approach to the right coronary artery, however, carries additional technical difficulties, and careful patient selection may be required to achieve optimal results.

A multi-centre randomised controlled trial of minimally invasive direct coronary bypass grafting versus percutaneous transluminal coronary angioplasty with stenting for proximal stenosis of the left anterior descending coronary artery.

OBJECTIVES: To compare the clinical- and cost-effectiveness of minimally invasive direct coronary artery bypass grafting (MIDCAB) and percutaneous transluminal coronary angioplasty (PTCA) with or without stenting in patients with single-vessel disease of the left anterior descending coronary artery (LAD). DESIGN: Multi-centre randomised trial without blinding. The computer-generated sequence of randomised assignments was stratified by centre, allocated participants in blocks and was concealed using a centralised telephone facility. SETTING: Four tertiary cardiothoracic surgery centres in England. PARTICIPANTS: Patients with ischaemic heart disease with at least 50% proximal stenosis of the LAD, suitable for either PTCA or MIDCAB, and with no significant disease in another vessel. INTERVENTIONS: Patients randomised to PTCA had local anaesthetic and underwent PTCA according to the method preferred by the operator carrying out the procedure. Patients randomised to MIDCAB had general anaesthetic. The chest was opened through an 8-10-cm left anterior thoracotomy. The ribs were retracted and the left internal thoracic artery (LITA) harvested. The pericardium was opened in the line of the LAD to confirm the feasibility of operation. The distal LITA was anastomosed end-to-side to an arteriotomy in the LAD. All operators were experienced in carrying out MIDCAB. MAIN OUTCOME MEASURES: The primary outcome measure was survival free from cardiac-related events. Relevant events were death, myocardial infarction, repeat coronary revascularisation and recurrence of symptomatic angina or clinical signs of ischaemia during an exercise tolerance test at annual follow-up. Secondary outcome measures were complications, functional outcome, disease-specific and generic quality of life, health and social services resource use and their costs. RESULTS: A total of 12,828 consecutive patients undergoing an angiogram were logged at participating centres from November 1999 to December 2001. Of the 1091 patients with proximal stenosis of the LAD, 127 were eligible and consented to take part; 100 were randomised and the remaining 27 consented to follow-up. All randomised participants were included in an intention-to-treat analysis of survival free from cardiac-related events, which found a non-significant benefit from MIDCAB. Cumulative hazard rates at 12 months were estimated to be 7.1 and 9.2% for MIDCAB and PTCA, respectively. There were no important differences between MIDCAB and PTCA with respect to angina symptoms or disease-specific or generic quality of life. The total NHS procedure costs were 1648 British pounds and 946 British pounds for MIDCAB and PTCA, respectively. The costs of resources used during 1 year of follow-up were 1033 British pounds and 843 British pounds, respectively. CONCLUSIONS: The study found no evidence that MIDCAB was more effective than PTCA. The procedure costs of MIDCAB were observed to be considerably higher than those of PTCA. Given these findings, it is unlikely that MIDCAB represents a cost-effective use of resources in the reference population. Recent advances in cardiac surgery mean that surgeons now tend to carry out off-pump bypass grafting via a sternotomy instead of MIDCAB. At the same time, cardiologists are treating more patients with multi-vessel disease by PTCA. Future primary research should focus on this comparison. Other small trials of PTCA versus MIDCAB have now finished and a more conclusive answer to the original objective could be provided by a systematic review.

Technical adjuncts in beating heart surgery comparison of MIDCAB to off-pump sternotomy: a meta-analysis.

OBJECTIVES: The technical aspects of minimal invasive surgery are discussed, together with a comparison of off-pump MIDCAB with off-pump sternotomy, with special respect to outcomes of death, infarct and anastomoses. METHODS: Technical aspects of beating heart surgery are described under the headings: Trauma; Access; Stabilisation; Ischaemia; Haemostasis; Suturing; and Circulatory support. Data from papers and meetings on minimal invasive surgery were collated to September 1998 and correlated with the unit of origin. Percentage figures were back calculated to provide an actual number from which a new data base was obtained relevant to the reporting incidence. For statistical analysis a Chi squared test with Yates correction was used. RESULTS: Sixty-three centres reported 3304 cases of MIDCAB surgery (M) and 21 centres reported over 3060 cases of off-pump surgery through a sternotomy (S). There was no difference in early or late death rates between the two groups (1.6% M:2.2% S). There was a higher infarct rate with MIDCAB (2.9% M: 1.45% S; P < 0.03). The occlusion and stenosis rates for MIDCAB were 3.9 and 6.6% whilst for sternotomy off-pump they were 4.9 and 1.4%. The stenosis difference was significant at the P < 0.001 level. A combined occlusion and stenosis rate showed a higher incidence with MIDCAB (10.5%), than sternotomy 6.4% (P < 0.08). Four major series showed comparative data before and after stabiliser usage in MIDCABs. The stenosis rate was significantly reduced with stabilisation from 9.6 to 3.7% (P < 0.002) as was the combined occlusion and stenosis rate from 16 to 5.0% (P < 0.0001). In the total series there was no significant difference in length of stay (4.6 days), incidence of atrial fibrillation (9%), or between conversion to sternotomy(MIDCAB group) or to bypass (sternotomy group) (5%) between the two groups (M and S). Grafting the right coronary artery by MIDCAB produced worse results than for the left anterior descending artery (LAD). CONCLUSIONS: There is an important failure rate with beating heart surgery; stabilisers reduce this risk and are essential tools in both MIDCAB and beating heart surgery and encourages the further use of minimally invasive approaches.

Correction of double outlet left ventricle in a patient with haemophilia "A".

A seventeen year old patient with factor VIII deficiency underwent correction of a double outlet left ventricle, using a porcine valved conduit (Hancock). Bleeding was controlled by the use of multiple factor VIII concentrate infusions. The patient made a good recovery.

Harvesting the radial artery: does it affect early postoperative hand function?

BACKGROUND: The radial artery (RA) is increasingly being used as a conduit for coronary artery bypass grafting. Previous studies have demonstrated that there is no significant deterioration in hand function in the long term. The aim of this study was to assess whether removal of the RA caused any alteration in the function or power of the hand 5 days postoperatively that would affect the patient's ability for self care on returning home. METHODS: A consecutive series of 37 patients undergoing RA harvesting was assessed over a period of 12 months from August 2000 to July 2001 as part of a prospective controlled trial. Grip power and fine motor skills in the operated hand were assessed preoperatively with an elasticated grip strength tester and an 18-hole peg board. This test was repeated 5 days postoperatively. The results were analyzed with a paired-sample t test to assess whether there was a significant difference between preoperative and postoperative hand function. RESULTS: The analysis showed that there was no statistically significant difference in fine motor function or grip power following surgery to harvest the RA. CONCLUSION: This study provides evidence to suggest that the RA can be safely harvested for use as a conduit in coronary artery bypass grafting, with no significant short-term deterioration in hand function.

The effect of a 'fast-track' unit on the performance of a cardiothoracic department.

OBJECTIVE: The objective of this study was to describe the impact of a 'fast-track' unit, combined with a computerised system for information collection and analysis, on the clinical practice and finance of a cardiothoracic department over the first 12 month period of its application. METHODS: Within 12 months, starting December 1996, 642 major cardiothoracic cases were performed at the Cardiothoracic Department, St Mary's Hospital, London, after the establishment of a 3-bed 'fast-track' unit, which was supported by a computerised system for admission planning and a pre-admission clinic. The main outcome measures were operating numbers, financial income, patient recovery and operative mortality. RESULTS: The 'fast-track' unit resulted in an increase of the operating numbers (11.3% increase in major cardiac cases) and income (38%), as compared with the year before. Some 525 patients out of 642 (81.8%) were scheduled for the 'fast-track' unit and 492 (93.7%) were successfully 'fast-tracked'. Coronary artery bypass grafting operations had the lowest 'fast-track' failure and mortality rates. Re-do operations and complex coronary procedures presented a high 'fast-track' failure rate of approximately 20-25%. Low cardiac output, postoperative bleeding and respiratory problems were the most frequent causes for 'fast-track' failure. CONCLUSIONS: The development of a 'fast-track' unit, supported by a computerised system for information collection and analysis and a pre-admission clinic, has resulted in a substantial improvement of operating numbers and financial income, without adversely affecting the clinical results. This task demanded close collaboration between a dedicated list manager and a designated member of the medical team. Patient selection with appropriate 'fast-track,' criteria may improve further the efficiency of 'fast-track' units in the future.

Management of hypopharyngeal carcinoma: a 6-year review.

A retrospective review of 16 consecutive cases of squamous carcinoma of the hypopharynx treated by pharyngo-laryngo-oesophagectomy (PLO) and gastric transposition with a thoracotomy as part of the surgical technique is presented. An operative mortality of 6% and a hospital mortality of 12% occurred. Other complications are discussed. No significant morbidity or mortality occurred as a result of the thoracotomy. A comparison is made with the extra-thoracic technique of gastric transposition.

Disease of the left main coronary artery: early surgical results and their association with carotid artery stenosis.

OBJECTIVES: To review the results of surgical revascularisation for left main coronary artery stenosis and the associated vascular pathology that is responsible for cerebrovascular complication. PATIENTS: 60 patients (45 men, 15 women) (mean age 61.3 (39-79)) who underwent revascularisation for stenosis of the left main stem coronary artery (LMS) between January 1987 and August 1990 were compared with an age and sex matched control group of patients undergoing revascularisation for triple vessel disease during the same period. OUTCOME MEASURES: In-hospital morbidity and operative mortality. RESULTS: 24 patients in the LMS group presented with unstable angina. The left ventricular ejection fraction was less than 50% in 30 patients and less than 30% in nine. 17 patients (28%) had large vessel extracranial carotid artery disease and 10 patients had vascular disease of the lower limbs. In six patients atheromatous plaques were noted in the ascending aorta during surgery. There was no in-hospital mortality. In-hospital morbidity included neurological deficits in five (8.3%), arrhythmias in seven (11.6%), and pulmonary complications in six (10%) patients. The incidence of carotid artery disease in the LMS group was significantly higher (p = 0.04). Atheromatous plaque in the ascending aorta and postoperative neurological complications were more common patients with LMS. CONCLUSIONS: The incidence of carotid artery disease was higher and postoperative cerebrovascular complications were more common in patients who had coronary artery revascularisation for stenosis of the left main stem coronary artery. The early surgical results were excellent. These findings suggest that for optimum perioperative management patients with stenosis of the left main coronary artery should be screened for carotid artery disease before bypass surgery.

Comparison of measured and computed epicardial potentials from a patient-specific inverse model.

This study reports the first direct comparison of measured and computed epicardial potentials in which the specific anatomy of a test subject has been used to calculate the inverse electrocardiographic model. It is now feasible to obtain low-noise body surface potential maps and to incorporate accurate anatomic data into inverse procedures for the purpose of computing epicardial potential distributions. The direct verification of computed human epicardial distributions remains an important goal. The experiment reported here obtained direct measurements from six transcutaneous pacing wires that were attached to points on the epicardial surface of the human heart in an intact subject. From the same subject, a magnetic resonance scan was used to produce a specific thoracic model consisting of 5-mm cubes. The forward model uses the finite difference method to compute a forward transfer matrix that relates each of 26 epicardial regions to body surface measurements. The inverse computation was performed by zero-order Tikhonov regularization. Body surface potentials were used in the inverse procedure to compute epicardial potentials, which were then compared with direct epicardial measurements. The computed epicardial potentials were compared to the measured ones by correlation, which gave an amplitude-independent measure of similarity. Amplitude differences and time delays in computed potentials were observed, but the morphologic trend was generally well recovered. The results obtained indicate the sensitivity of the inverse model to a number of factors. The robustness of computed epicardial distributions to errors in assumed lung conductivity is shown. Results from a nonpatient-specific, but realistic, torso model are presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma fibronectin and complement activation in coronary bypass surgery.

In patients with severe sepsis, plasma fibronectin concentrations are reduced and complement is activated. It is not known whether complement activation interferes with plasma fibronectin. Cardiopulmonary bypass is known to activate complement. We have therefore used this operation to study the effect of complement activation on plasma fibronectin in the absence of sepsis. After 15 min of bypass the percentage changes of plasma fibronectin and haematocrit were similar (65.9 +/- s.e.m. 4.8 and 67.0 per cent +/- s.e.m. 2.3, respectively), but the changes in C3 and C5 (58.4 +/- s.e.m. 4.8 per cent and 52.5 per cent +/- s.e.m. 2.1) were significantly greater than those of the haematocrit, indicating complement consumption. During the first 60 min of bypass there was a significant increase in the neutrophil count which is compatible with complement activation. It is unlikely that complement activation alone, in the absence of sepsis, contributes to the reduction of plasma fibronectin concentrations.

Use of a pulsatile beating heart model for training surgeons in beating heart surgery.

BACKGROUND: Coronary artery bypass on the beating heart has undergone resurgence with the introduction of minimally invasive techniques and new stabilizing devices. It is important to develop a method for training surgeons to perform accurate anastomoses despite cardiac motion and to develop the skills needed for consistent results in this demanding field. METHODS: A prosthetic model of the beating heart was created by Limbs and Things, Ltd. (Bristol, UK) and used in our center to simulate clinical situations of beating heart surgery. Anastomotic quality was evaluated using a pre-established set of criteria on patency and suturing with each anastomosis graded on a 12-point scale. RESULTS: The average scores for trainees using the Pulsatile Beating Heart Model were 8.5 while that of the expert surgeon with MIDCAB experience was 11. Defects seen included cross-wall suturing and significant narrowing of the toe of the anastomosis. Scores improved with increasing practice during each session. Operators with more clinical experience scored higher. All surgeons felt the model duplicated the exposure and feel of the tissue characteristic of clinical cases. CONCLUSIONS: The beating heart simulator provides excellent training for new as well as experienced surgeons, provides visual feedback of anastomotic errors, and instills increasing confidence in the participants in their ability to construct accurate anastomoses on the beating heart.

Effect of halothane on myocardial infarct size in rats.

The effect of halothane on myocardial infarction caused by ligation of the left descending coronary artery was studied in rats. The extent of infarction was quantified 48 hours after ligation of the artery by planimetric measurement of left ventricular slices stained with nitrobluetetrazolium. Animals exposed to halothane one per cent for three hours after the coronary ligation were compared with a control group which received halothane for only 5-7 minutes during surgery. It was found that halothane caused a small increase in infarction size (31.3 +/- 1.5 per cent of the left ventricle compared to 25.7 +/- 2.3 per cent, p less than 0.05). This effect was accompanied by a decrease in systolic blood pressure (91 +/- 2 mmHg compared to 113 +/- 3 mmHg, p less than 0.001). Heart rate did not change significantly. Analysis of our results in comparison to previously reported data on the effect of halothane on myocardial ischaemia in different experimental conditions shows that halothane may produce beneficial as well as detrimental effect on ischaemic injury to the myocardium. The latter can result when the drug causes marked hypotension in the absence of a significant decrease in heart rate.

Primary pericardial mesothelioma presenting as tuberculous pericarditis.

Ante-mortem diagnosis of primary pericardial mesothelioma is very rare. We report a case which presented clinically as tuberculous constrictive pericarditis. The patient underwent pericardial resection with an immediate haemodynamic benefit, although the malignant process progressed, and he died 14 weeks later.

Expandable metal stents for non-malignant bronchial obstruction.

An expandable metal stent was inserted to relieve bronchial obstruction following lobectomy for localised squamous carcinoma which had not been relieved by bronchoplasty with a Goretex flap. This resulted in substantial improvement in lung function and exercise tolerance for nine months, following which severe inflammation around the stents required residual pneumonectomy.