Impact of diabetes mellitus on the improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

BACKGROUND: Although it has been reported that coronary artery bypass grafting (CABG) for multivessel disease markedly improves several parameters of signal-averaged electrocardiography (SAECG), its beneficial effect on SAECG is variable. The hypothesis of the present study was that the presence of diabetes mellitus (DM) affects the improvement in SAECG after CABG. METHODS AND RESULTS: Pre- and post-operative SAECGs were recorded in 100 consecutive patients who underwent complete surgical revascularization. Changes in the following parameters were compared between the diabetic (n=43) and non-diabetic (n=57) patients: filtered QRS duration (dQRS), root mean square voltage in the terminal 40 s of the QRS complex (RMS40), and duration of the terminal low-amplitude signal lower than 40 microV (LAS40). Although baseline characteristics and the occurrence of late potentials were similar in both groups, quantitative improvements in the SAECG parameters after CABG were significantly greater in non-diabetic than in diabetic patients (dQRS: 109 +/- 22 ms vs 102 +/- 19 ms in diabetics and 106 +/- 21 ms vs 88 +/- 11 ms in non-diabetics; p=0.028, RMS40: 55 +/- 46 microV vs 65 +/- 38 microV in diabetics and 50 +/- 37 microV vs 76 +/- 37 microV in non-diabetics; p=0.037, LAS40: 31 +/- 20 ms vs 26 +/- 17 ms in diabetics and 32 +/- 12 ms vs 17 +/- 8 ms in non-diabetics; p=0.007, respectively). CONCLUSIONS: The presence of DM limits the CABG-induced improvement in SAECG. In diabetic patients, therefore, perioperative changes of the SAECG must be interpreted with caution.

Mitral valve surgery in a patient with spinal progressive muscular atrophy: report of a case.

We describe our experience in treating a 69-year-old man with spinal progressive muscular atrophy (SPMA), who underwent a mitral valve replacement. He was admitted for dyspnea, and surgery was indicated for severe mitral insufficiency associated with inferior myocardial infarction. He had been aware of muscle weakness and received a diagnosis of SPMA 18 years previously. Worsening muscle atrophy had led to the need for him to use a wheelchair in his daily life. A preoperative examination revealed markedly reduced pulmonary function (% volume capacity = 44.8%). Because of an acute exacerbation of heart failure, the patient underwent an urgent mitral valve replacement with a 27-mm pericardial bioprosthesis. Although it took 42h to wean him from the mechanical ventilation and he suffered from pulmonary atelectasis after extubation, he was discharged from our hospital in a wheelchair 16 days after surgery. Respiratory management with bilevel positive airway pressure was thus found to be quite useful for patients with neuromuscular disease.

Mitral valve surgery in a patient with rheumatoid arthritis being treated with methotrexate.

We describe our experience of mitral valve surgery in a 74-year-old man with rheumatoid arthritis (RA). RA had been diagnosed 12 years previously and his symptoms were being controlled by drugs including methotrexate (MTX), which is potentially immuno- and myelo-suppressive. He was admitted for dyspnea, and surgery was indicated for severe mitral insufficiency due to posterior leaflet prolapse. According to the recommendations of orthopedic surgeons, the administration of the MTX was discontinued at two weeks prior to the operation, in which the prolapsed leaflet was excised, repaired, and annuloplasty were performed with a 30 mm prosthetics ring. The patient recovered uneventfully and MTX was resumed one week after surgery. Since MTX has been recently approval for treatment of RA in Japan, Japanese surgeons should pay attention to the appropriate perioperative use of this drug.

Quantitative improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

Abnormal signal-averaged electrocardiography (SAECG) reflects slow and heterogeneous myocardial conduction, predicting ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease. The purpose of this study was to investigate the quantitative effect of coronary artery bypass grafting (CABG) on SAECG, which is still controversial, and to identify the factors that are related to it. Pre- and postoperative SAECGs were recorded in 100 patients who underwent CABG. Compared parameters included filtered QRS duration (dQRS), root mean square voltage in the terminal 40 ms of the QRS complex (RMS40), and duration of the terminal low-amplitude signal less than 40 microV (LAS40). All 3 parameters in SAECG improved significantly after CABG (dQRS: 105+/-21 ms-->99+/-18 ms, RMS40: 55+/-45 microV-->65+/-41 microV, LAS40: 29+/-19 ms-->25+/-12 ms). The improvements in SAECG were greater in patients who underwent complete revascularization and in those without prior myocardial infarction. In conclusion, CABG improved SAECG quantitatively, even in patients with normal SAECG. However, this improving effect was variable and closely related to the presence of prior myocardial infarction and the completeness of revascularization.

Beneficial effects of bilevel positive airway pressure after surgery under cardiopulmonary bypass.

To support injured lungs, we have been applying bilevel positive airway pressure for adult patients undergoing surgery with cardiopulmonary bypass. Among 120 consecutive patients, 31 patients whose PaO2/FiO2 decreased to less than 180 after extubation assigned to the intermittent 15 min bilevel positive airway pressure (7.3+/-3.6 times per patient). Bilevel positive airway pressure improved oxygenation (PaO2/FiO2: 128+/-43 vs. 198+/-62, P=0.004) and allowed the patients with poor oxygenation after extubation to maintain PaO2/FiO2 levels similar to those of the patients without bilevel positive airway pressure. In conclusion, the bilevel positive airway pressure therapy after extubation was effective to improve lung oxygenation non-invasively in adult patients undergoing more invasive surgery with prolonged cardiopulmonary bypass.

Constrictive pericarditis caused by calcification and organized hematoma 30 years after cardiac surgery.

A 54-year-old man, who had undergone atrial septal defect (ASD) closure 30 years previously, was admitted for exertional dyspnea and chest oppression. He presented with right pleural effusion and hepatomegaly. Hemodynamic characteristics were consistent with constrictive pericarditis caused by multiple cystic lesions anterior to the main pulmonary artery and right ventricle, and severe calcification over the posterior and diaphragmatic sides of the heart. Magnetic resonance imaging was useful for differential diagnosis of the cystic mass and at surgery, it was revealed that the cystic lesions were old hematoma without cells. Pericardiectomy and removal of the calcification were performed safely using an ultrasonic scalpel, without cardiopulmonary bypass, resulting in hemodynamic improvement and relief of his symptoms.

Significance of the initial arterial lactate level and transpulmonary arteriovenous lactate difference after open-heart surgery.

PURPOSE: This study was conducted to determine the clinical significance of the initial lactate level and its transpulmonary difference after open-heart surgery in adult patients. METHODS: The initial postoperative lactate levels were obtained from both radial and pulmonary arteries (La, Lv) in 65 consecutive patients undergoing coronary (n = 46), valve (n = 8), and aortic (n = 11) surgery. We analyzed the relationships between the perioperative factors and La and transpulmonary arteriovenous lactate difference (%La-v = 100(La - Lv)/Lv). RESULTS: La and % La-v were not correlated with the preoperative factors of age, pulmonary function, or emergency surgery. La significantly correlated with the cardiopulmonary bypass time, initial arterial pH, initial PaO2/FiO2, SvO2, O2 consumption, O2 extraction rate, and the peak value of creatine phosphokinase. The %La-v significantly correlated with the aortic cross-clamp time, the lowest rectal temperature, the duration of intubation, and PaO2/FiO2 after extubation. CONCLUSION: La may be an indicator of the invasiveness of the surgery, while %La-v may be a predictor of postoperative pulmonary function. Both La and %La-v, as an initial value in the intensive care unit, may play an important role in planning the postoperative management of patients undergoing open-heart surgery.

Effects of skeletonization on intraoperative flow and anastomosis diameter of internal thoracic arteries in coronary artery bypass grafting.

BACKGROUND: We examined the hypothesis that complete skeletonization of an internal thoracic artery (ITA) results in increased diameter of the graft for anastomosis and therefore improves graft flow in coronary artery bypass grafting. METHODS: We studied 65 consecutive patients who underwent coronary artery bypass grafting, in which the left ITA was anastomosed to the left anterior descending artery. The first 20 consecutive ITA were harvested as a pedicle (group P) and later 45 consecutive ITAs were harvested as an ultrasonically skeletonized graft (group S). Intraoperative ITA graft mean flows were obtained with a transit-time flowmeter. Three diameters of the ITA graft were measured quantitatively in postoperative angiograms performed 14 +/- 5 days after the coronary artery bypass grafting; D1, at the origin from the subclavian artery; D2, at the level of the second intercostal space; and D3, just proximal to the anastomosis. RESULTS: Intraoperative mean flow was significantly greater in group S than in group P (S: 42.6 +/- 29.1 mL/min versus P: 26.4 +/- 16.1 mL/min, p = 0.03). Although the diameters D1 and D2 were not significantly different between groups, D3 was significantly larger in group S than in group p (S: 1.77 +/- 0.28 mm versus P: 1.57 +/- 0.17 mm, p = 0.02). CONCLUSIONS: Compared with pedicle harvesting, complete skeletonization of ITA may make it possible to anastomose an ITA with a larger diameter in coronary artery bypass grafting, which leads to increased graft flow by decreasing vascular resistance.