[Subscapular elastofibroma].

Elastofibroma is a tumor that is localized mainly at the subscapular region. We report 2 cases of subscapular elastofibromas. Case 1, 75-year-old woman was seen at the hospital because of a left dorsal tumor. Computed tomography (CT) scan revealed the tumor of 6 cm in diameter in the inferior angle of left scapula. The patient underwent excision of the tumor. Case 2, 90-year-old man underwent excision a tumor of 5 cm in diameter in the inferior angle of right scapula simultaneously with the operation of right lung cancer. Histological examinations showed increased elastic fiber with elastica van Gieson staining. These specimens confirmed the diagnosis of elastofibroma There have been no signs of recurrence after surgery.

Hypoxic hepatitis with marked elevation of serum ferritin probably due to activation of intrahepatic macrophages: another form of hypoxic hepatitis hitherto not reported?

BACKGROUND AND STUDY AIMS: Hypoxic hepatitis (HH) is an acute liver injury that develops in patients with underlying diseases, such as heart failure, respiratory failure, septic/toxic shock. However, some patients do not have underlying diseases or episodes which are known to result in HH. Here, we analyzed the clinical characteristics of this particular patient group (called 'unknown HH' hereafter) to understand its pathogenesis. PATIENTS AND METHODS: Between October 2010 and January 2016, 157 consecutive patients with acute liver injury were admitted to our hospital. Among these patients, 15 patients were categorized as unknown HH. Medical histories and blood test results of unknown HH were analyzed. RESULTS: Among 15 patients of unknown HH, 11 were habitual drinkers and all experienced one of digestive symptoms which might result in mild hypovolemia such as vomiting, diarrhea, appetite loss, and epigastralgia. All patients of unknown HH presented marked elevation of serum ferritin concentration paralleled with aspartate transaminase (AST), alanine transaminase (ALT), and lactate dehydrogenase (LDH) concentrations. The serum levels of ferritin, ALT, LDH, and prothrombin time-international normalized ratio (PT-INR) were rapidly decreased during hospitalization and all 15 patients of unknown HH recovered without any complication. CONCLUSIONS: We found the particular group of HH with marked elevation of serum ferritin probably due to intrahepatic macrophage activation. Anti-inflammatory treatments might be effective for this group of hypoxic hepatitis.

Effects of exercise training on autonomic modulation and mood symptoms in patients with obstructive sleep apnea.

We evaluated the effects of exercise training (ET) on the profile of mood states (POMS), heart rate variability, spontaneous baroreflex sensitivity (BRS), and sleep disturbance severity in patients with obstructive sleep apnea (OSA). Forty-four patients were randomized into 2 groups, 18 patients completed the untrained period and 16 patients completed the exercise training (ET). Beat-to-beat heart rate and blood pressure were simultaneously collected for 5 min at rest. Heart rate variability (RR interval) was assessed in time domain and frequency domain (FFT spectral analysis). BRS was analyzed with the sequence method, and POMS was analyzed across the 6 categories (tension, depression, hostility, vigor, fatigue, and confusion). ET consisted of 3 weekly sessions of aerobic exercise, local strengthening, and stretching exercises (72 sessions, achieved in 40±3.9 weeks). Baseline parameters were similar between groups. The comparisons between groups showed that the changes in apnea-hypopnea index, arousal index, and O2 desaturation in the exercise group were significantly greater than in the untrained group (P<0.05). The heart rate variability and BRS were significantly higher in the exercise group compared with the untrained group (P<0.05). ET increased peak oxygen uptake (P<0.05) and reduced POMS fatigue (P<0.05). A positive correlation (r=0.60, P<0.02) occurred between changes in the fatigue item and OSA severity. ET improved heart rate variability, BRS, fatigue, and sleep parameters in patients with OSA. These effects were associated with improved sleep parameters, fatigue, and cardiac autonomic modulation, with ET being a possible protective factor against the deleterious effects of hypoxia on these components in patients with OSA.

Early recurrence after surgical resection in patients with pathological stage I non-small cell lung cancer.

INTRODUCTION: Early recurrence is observed even in patients who undergo complete resection and had pathological (p-) stage I. Therefore, we focused on early recurrence, and attempted to elucidate the relationship between early recurrence and clinicopathological factors. METHODS: Between May 1993 and December 2005, 1201 patients with non-small cell lung cancer (NSCLC) underwent surgical treatment at our institution. Of these, 402 patients who underwent complete resection and had p-stage I NSCLC were retrospectively analyzed for clinicopathological factors. Patients were divided into four groups according to the period between surgery and recurrence (R): no recurrence (NR, n = 331), late recurrence (LR, n = 28, R > 2 years), intermediate recurrence (IR, n = 22, 1 year < R < or = 2 years), and early recurrence (ER, n = 21, R < or = 1 year). RESULTS: The overall 5-year survival rate for patients with p-stage I was 79.9 %. The overall 5-year survival rates were 91.0 %, 55.6 %, 17.1 %, and 7.5 % for the NR, LR, IR, and ER group, respectively. Preoperative high CEA level, lymphatic permeation, and pleural invasion were proven to be independent factors for overall recurrence. Moreover, multivariate analysis showed that preoperative CEA level, pathological T factor, lymphatic permeation, vascular invasion, and pleural invasion influenced early recurrence within one year. CONCLUSIONS: The present study demonstrated that preoperative CEA level, pathological T-factor, lymphatic permeation, vascular invasion, and pleural invasion were independent prognostic factors for early recurrence within one year, even in patients with pathological stage I. In patients with these factors, adjuvant therapy may be indicated since this may improve their survival.

[Risk factors of recurrence in resected stage I non-small cell lung cancer].

We reviewed risk factors of recurrence in resected pathological stage I non-small cell lung cancer (I NSCLC). Objective is 229 complete resected I NSCLC in our department. Risk factors of recurrence were carcinoembryonic antigen (CEA), histology, differentiation, lymphatic invasion, blood vessel invasion, pleural invasion and tumor size. By univariate analysis, lymphatic invasion (p=0.009), blood vessel invasion (p=0.008), pleural invasion, p1 (p=0.013), p2 (p=0.001), and tumor size (value of cut off was 2 cm) were significant risk factors of recurrence. By multivariate analysis, blood vessel invasion (p=0.004), pleural invasion (p1 or p2) [p=0.001], were significantly risk factors of recurrence. It was suggested that I NSCLC presenting pathological blood vessel invasion and/or pleural invasion should be recognized as cases with a high risk of recurrence, and a strict follow-up and adjuvant therapy should be in consideration.

Effects of exercise training on autonomic modulation and mood symptoms in patients with obstructive sleep apnea

We evaluated the effects of exercise training (ET) on the profile of mood states (POMS), heart rate variability, spontaneous baroreflex sensitivity (BRS), and sleep disturbance severity in patients with obstructive sleep apnea (OSA). Forty-four patients were randomized into 2 groups, 18 patients completed the untrained period and 16 patients completed the exercise training (ET). Beat-to-beat heart rate and blood pressure were simultaneously collected for 5 min at rest. Heart rate variability (RR interval) was assessed in time domain and frequency domain (FFT spectral analysis). BRS was analyzed with the sequence method, and POMS was analyzed across the 6 categories (tension, depression, hostility, vigor, fatigue, and confusion). ET consisted of 3 weekly sessions of aerobic exercise, local strengthening, and stretching exercises (72 sessions, achieved in 40±3.9 weeks). Baseline parameters were similar between groups. The comparisons between groups showed that the changes in apnea-hypopnea index, arousal index, and O2 desaturation in the exercise group were significantly greater than in the untrained group (P<0.05). The heart rate variability and BRS were significantly higher in the exercise group compared with the untrained group (P<0.05). ET increased peak oxygen uptake (P<0.05) and reduced POMS fatigue (P<0.05). A positive correlation (r=0.60, P<0.02) occurred between changes in the fatigue item and OSA severity. ET improved heart rate variability, BRS, fatigue, and sleep parameters in patients with OSA. These effects were associated with improved sleep parameters, fatigue, and cardiac autonomic modulation, with ET being a possible protective factor against the deleterious effects of hypoxia on these components in patients with OSA.

Quantification of the Na+/K(+)-pump in solubilized tissue by the ouabain binding method coupled with high-performance gel chromatography.

Membrane-bound Na+/K(+)-ATPase purified from dog kidney outer medulla was solubilized with octaethylene glycol n-dodecyl ether (C12E8) and incubated with [3H]ouabain in the presence of NaCl. ATP and MgCl2 for 10 min at 0 degrees C. The resulting enzyme was separated, by high-performance gel chromatography executed at 0.2 degrees C. Mainly into its (alpha beta)2-diprotomer and alpha beta-protomer, which both bound stoichiometrically to [3H]ouabain. The amounts of ouabain that bound to the tissue itself and its microsomes could be estimated in the same way, as [3H]ouabain was found to bind only to the diprotomer and protomer they possessed. The amounts of ouabain that bound to them in the solubilized state were at least 5-times higher than those that did so when they were non-solubilized, suggesting that the surfactant rendered the enzyme accessible to ouabain. When the solubilized tissue (138 mg ml-1 wet tissue) was reacted with ouabain in the presence of 0.1 M NaCl and 4.8 mM MgCl2 for 10 min at 0 degrees C, maximal ouabain binding was attained in the presence of 18.3 microM [3H]ouabain, 1.2 mM ATP and 3 to 5 mg ml-1 C12E8, which was common to the outer medulla and human colon cancer cells. The present method enabled the pump number in protein and tissue samples in the range 7.2 x 10(-9) (purified pump) to 1.5 x 10(-12) (cancer tissue) mol/mg protein to be estimated within 2 h.

Human L-type amino acid transporter 1 (LAT1): characterization of function and expression in tumor cell lines.

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential amino acids for cell growth and cellular responses, and in distributing amino acid-related compounds.

Characteristics of alveolar macrophages in experimental septic lung.

We investigated the pathogenesis of lung injury in sepsis (septic adult respiratory distress syndrome) by focusing on the functional changes of alveolar macrophages (AMs). Sepsis was induced in male WK rats by cecal ligation and puncture. Histological examination of the lungs from this experimental model revealed edematous change at 24 h after the surgery. The protein and endotoxin concentrations in the bronchoalveolar lavage fluid (BALF) increased with time after the surgery. The time course studies of AM function after surgery indicated that AMs from septic rats were activated by endotoxins. Specifically, this was suggested by the finding that AM adherence to and spreading on a plastic dish had increased. On stimulation, these AMs enhanced generation of superoxide anions and increased release of lysosomal enzymes, such as beta-glucuronidase. On the other hand, AMs in sepsis generated much smaller amounts of arachidonate lipoxygenase metabolites, such as leukotriene B4 (LTB4) and 12- and 5-hydroxyeicosatetraenoic acids (HETEs), on stimulation than did AMs from sham rats or untreated rats. However, the concentrations of immunoreactive LTC4 in the BALF of septic rats seemed to be higher than in untreated rats. It is suggested that the AMs of septic rats released lipoxygenase metabolites in alveoli and that these AMs could not be stimulated in vitro. These functional changes in the AMs of septic rats progressed along with the sepsis. These results implicate AMs in the development and progression of septic lung injury by releasing superoxide anions, beta-glucuronidase, and arachidonate metabolites. Furthermore, we speculate that reduced production of LTB4 by septic AMs may increase host susceptibility to severe pulmonary infection during septic ARDS.

Noninvasive measurement of central sensory and motor conduction.

Potentials evoked by median and peroneal nerve stimulation were digitally filtered between 300 and 2,500 Hz to measure early latency components and assess sensory cord conduction velocity. Short (R1) and long (R2) latency reflex responses were recorded from contracting thenar and tibialis anterior muscles. R1 is considered a spinal reflex akin to the H-reflex. Clinical evidence suggests that R2 involves a reflex arc with turnaround at the motor cortex. Sensory-motor cord velocity was derived from the latencies of R1 and R2. The method can be used to compare peripheral and central sensory conduction or conduction in central sensory and motor pathways.

Plasmacytoma of the lung associated with nodular deposits of immunoglobulin.

A case of extramedullary plasmacytoma of the lung associated with nodular immunoglobulin deposits is presented. The main tumor was located in the posterior basal segment of the lower lobe of the left lung and showed intrabronchial polypoid growth. Multiple metastatic tumors were observed in regional lymph nodes and the visceral and parietal pleura. Histologically, the tumor was composed of sheets of plasma cells with mild atypia. A large amount of amorphous material resembling amyloid was observed in the tumors, and was more marked in the metastatic lesions. Immunohistochemically, the tumor cells were shown to contain monoclonal IgG-kappa immunoglobulin. The amorphous deposits were not identical to amyloid since congo red stain was negative and amyloid fibrils were not observed ultrastructurally. By Western blotting, immunoglobulin (IgG, kappa) was identified as the major component in an extract from the nodular deposits. In the preoperative serum from the patient, M-protein (IgG-kappa) was detected by immunoelectrophoresis. Bone marrow examination revealed no abnormality.

Early development of Epstein-Barr virus-associated T-cell lymphoma after a living-related renal transplantation.

We herein report a case of Epstein-Barr virus (EBV)-associated T-cell lymphoma that developed within a month after a kidney transplantation. The recipient was a 37-year-old man who had evidence of a previous EBV infection. Cyclosporine, methylprednisolone, and azathioprine were used for immunosuppression, and acute rejection was treated with high-dose methylprednisolone. The lactate dehydrogenase level started to increase on day 24 and thereafter peaked on day 37 while also demonstrating progressive jaundice and a bleeding tendency. A transplant nephrectomy was done on day 37; however, the patient could not recover and eventually died of respiratory failure as a result of diffuse pulmonary edema. A pathological examination of the resected kidney revealed a diffuse proliferation of large atypical lymphoid cells in the parenchyma. Immunohistochemically, the tumor cells were positive for CD45 and T-cell marker, CD45RO, but negative for B-cell markers. EBV-encoded RNA was demonstrated within the neoplastic cells by in situ hybridization.

Use of serial semithin frozen sections to evaluate the co-localization of estrogen receptors and progesterone receptors in cells of breast cancer tissues.

The extent of co-expression of estrogen receptors (ER) and progesterone receptors (PgR) in breast cancer cells was examined immunocytochemically. Eight surgical cases of infiltrating ductal carcinoma designated as ER-positive and PgR-positive (ER+/PgR+) by enzyme immunoassay (EIA) were used. They were fixed with 4% formaldehyde and cut into serial frozen semithin sections. Using sections stained with either anti-ER or anti-PgR antibody, we ascertained the co-localization of ER and PgR in a single cell and estimated the ratio of the number of cells co-expressing ER and PgR. Twenty-six to 95% of the cells were immunopositive for both ER and PgR, 2-25% of them, varying in cases, were positive for ER but not for PgR, and <3% of the cells were positive for PgR but not for ER. The remaining 5-60% cells were positive for neither ER nor PgR. A significant percentage of breast cancer cells in tissues designated as ER+/PgR+ by EIA showed the phenotype of ER-positive but PgR-negative. The co-expression ratio of ER and PgR in biochemically detected ER+/PgR+ breast cancer may reflect a particular clinical parameter, such as the heterogeneous responsiveness of ER+/PgR+ breast cancers to hormonal treatment. Immunostaining of serial semithin frozen sections for two or more different antigens is a useful method to assess the correlation of localization of antigens.

Radiographic and scintigraphic courses of union in cervical interbody fusion: hydroxyapatite grafts versus iliac bone autografts.

UNLABELLED: This study investigated the radiographic and scintigraphic courses of union in cervical interbody fusion using hydroxyapatite (HA) grafts or iliac bone autografts. METHODS: Twelve patients underwent both serial plain radiography and bone scintigraphy during the 12 mo after surgery. Serial plain radiographs were obtained every month until the end of the study period. Bone scintigrams with 99mTc-hydroxymethylene diphosphonate (HMDP) were obtained at 2 wk and at 1, 2, 3, and 6 mo. Uptake of 99mTc-HMDP in the graft was expressed as a ratio of the counts in the graft to those in the axis. RESULTS: In the HA graft group, the plain radiographs of all patients showed a radiolucent stripe that disappeared 7.3 +/- 1.5 (mean +/- SD) months after surgery. In the autograft group, a radiolucent stripe around the graft was not seen for any patient, and union was confirmed by follow-up radiographs within 6 mo after surgery. The serial changes in the 99mTc-HMDP uptake ratio showed no difference between the 2 groups. The 99mTc-HMDP uptake ratio peaked 1 mo after surgery and decreased rapidly to a plateau within 2 mo. CONCLUSION: In the HA graft group, despite the presence of a radiolucent stripe around the graft for more than 6 mo, the scintigraphic course of union was not different from that in the autograft group. The likelihood is that the presence of a radiolucent stripe around the HA graft in the early months after surgery is not always a sign of pseudoarthrosis.

Glioma cell extracellular matrix metalloproteinase inducer (EMMPRIN) (CD147) stimulates production of membrane-type matrix metalloproteinases and activated gelatinase A in co-cultures with brain-derived fibroblasts.

Extracellular matrix metalloproteinase inducer (EMMPRIN) also called CD147, basigin or M6 in the human is a member of the immunoglobulin superfamily that is enriched on the surface of tumor cells and stimulates adjacent stromal cells to produce several matrix metalloproteinases (MMPs). In this study, we have demonstrated that coculturing of EMMPRIN-expressing human glioblastoma multiforme cells (U251) with brain-derived human fibroblasts not only stimulates production, but also activation of pro-gelatinase A (proMMP-2), an enzyme that is enriched in malignant gliomas and most likely crucial to tumor progression. Production of membrane types 1 and 2-MMPs (MT1-MMP and MT2-MMP), which are activators of proMMP-2, was also stimulated in these cocultures. Stimulation of MMP-2, MT1-MMP and MT2-MMP production was inhibited by anti-EMMPRIN monoclonal antibody in a dose-dependent manner. Thus, we have shown, for the first time, that EMMPRIN causes increased expression of MT1-MMP and MT2-MMP, as well as increased production and activation of MMP-2.

Comparative analysis of expression of hepatocyte growth factor and its receptor, c-met, in gliomas, meningiomas and schwannomas in humans.

Expression of hepatocyte growth factor (HGF) and c-met, a proto-oncogene that encodes a receptor for HGF, was examined in 45 cases of human primary intracranial tumors by means of RT-PCR. In gliomas, HGF and c-met mRNAs were preferentially expressed in high-grade tumors. Co-expression of both genes was observed in glioblastomas (6/15) and in one anaplastic astrocytoma (1/5) but not in low-grade astrocytomas (0/3). By contrast, the c-met gene was consistently expressed in meningiomas (12/14) and schwannomas (8/8). The presence of c-Met protein was confirmed in the tumor cells of glioblastoma, meningioma and schwannoma by immunohistochemical staining. Moreover, all of the schwannoma cases co-expressed the HGF gene. These observations suggest that HGF/c-met expression is somehow related to the disease progression in gliomas, whereas c-Met protein might have an important fundamental biological role in meningioma and schwannoma. Moreover, since all of the schwannoma cases concomitantly expressed the ligand (HGF) and the receptor (c-met) genes, HGF may act in an autocrine fashion in schwannoma.

Prognosis and survival in resected lung carcinoma based on the new international staging system.

A new TNM staging system was proposed and the previous system has been revised recently. To evaluate the new TNM staging system for lung cancer, we analyzed records of 1737 patients who underwent pulmonary resection at the National Cancer Center Hospital, Tokyo. With regard to clinical stages, three patients had occult carcinoma; 821 patients had stage I disease; 248 patients, stage II; 465 patients, stage IIIA; 82 patients, stage IIIB; and 118 patients, stage IV. The 5-year survival rates for the respective stages were 50.1% for stage I, 31.2% for stage II, 20.2% for stage IIIA, 5.1% for stage IIIB, and 7.9% for stage IV. In terms of postoperative stages, four patients were classified in stage 0, 536 in stage I, 221 in stage II, 559 in stage IIIA, 159 in stage IIIB, and 258 in stage IV. The 5-year survival rates were as follows: stage I, 65.0%; stage II, 42.9%; stage IIIA, 22.2%; stage IIIB, 5.6%; and stage IV, 7.5%. In both the clinical stage and the postoperative stage, there were significant prognostic differences between stage I and stage II, stage II and stage IIIA, and stage IIIA and stage IIIB, but there was no significant difference in 5-year survival rates between stage IIIB and stage IV.

Resection of tracheal carina for lung cancer. Procedure, complications, and mortality.

We studied 20 patients with lung cancer that invaded the tracheal carina who were operated on during a recent 12-year period. Fifteen patients underwent sleeve pneumonectomy, two had pneumonectomy, one had lobectomy with wedge resection of the carina, and two patients had sleeve resection of the carina followed by reconstruction of the carina. There were two patients with postsurgical stage IIIA lung cancer, 15 with stage IIIB, and three with stage IV disease that involved intrapulmonary metastases. However, the operations of 13 patients were curative resections in which the surgical margin was negative for disease. Sleeve pneumonectomy was performed only in the last 3 years of the study period, after we had confirmed the safety and good results of bronchoplastic surgery by our experience of 100 cases of sleeve lobectomy. Hence, the period of follow-up in this group is too short to assess long-term survival. Eleven patients are alive, three died within 1 month after operation (15%), three died in the hospital beyond 1 month after the operation, and three died after discharge from hospital. Nine of the 11 surviving patients have no evidence of disease 1 month to 2 1/2 years after the operation, but two are alive with supraclavicular lymph node metastases. The 1-year and 2-year survival rates for 17 cases (excluding the three operative deaths) were both 59% by the Kaplan-Meier method. Two different methods were used to adjust the difference of calibers of the trachea and the bronchus. The first method involved the shift of the edge of the cartilagonous portion of the bronchus against the edge of the cartilaginous portion of the trachea and the other involved cutting the tracheal wall as a wedge-shaped piece to shorten the diameter of the tracheal caliber. To prevent complications after resection of the tracheal carina in 11 recent cases with sleeve pneumonectomy, anastomoses were protected by a pedicle fat flap nourished by internal thoracic artery and vein. No postoperative complications of anastomoses developed in any of these cases.

Prognostic significance of pleural lavage cytology immediately after thoracotomy in patients with lung cancer.

Pleural lavage cytology immediately after thoracotomy was performed in 467 patients with lung cancer who had little or no pleural effusion. Forty-two patients (9.0%) had positive results. The positivity of pleural lavage cytology was significantly related to the degree of pleural extension of the tumor, microscopic pleural dissemination, cytologic results of minimal pleural effusion, pathologic stage, presence of lymphatic permeation or vascular invasion, and cell type (adenocarcinoma was predominant). The 3-year survival of the patients having negative and positive results of cytology were 68.7% and 22.9%, respectively. The prognosis of the group with positive results was as poor as that of patients with stage IIIB or IV disease. Pleural lavage cytology is an important prognostic factor that indicates microscopic exfoliation of cancer cells into the pleural cavity, that is, subclinical malignant pleural effusion.

What are the risk factors for arrhythmias after thoracic operations? A retrospective multivariate analysis of 267 consecutive thoracic operations.

Two hundred sixty-seven operations performed consecutively at the National Cancer Center Hospital, Tokyo, in 1990 were reviewed to define the prevalence, type, clinical course, and, especially, risk factors for arrhythmias after thoracic operations. Arrhythmias were identified in 63 operations (23.6%) and were more prevalent in several subgroups of patients than in others--those with lung cancer, pneumonectomy, mediastinal lymph node dissection, and those older than 70 years of age. Supraventricular tachycardias, of which atrial fibrillation was the most common, comprised 95.3% of the cases; bradyarrhythmia and ventricular ectopic beats were seen in only three and four cases, respectively. Arrhythmias were most likely to develop on the second day after the operation. Eighty percent of the arrhythmias disappeared within 3 days after onset, and sinus rhythm was finally restored with digitalis or other antiarrhythmic drugs in all patients except one, who had a myocardial infarction. Arrhythmias were not the direct cause of any of the seven in-hospital deaths. A multivariate analysis of 16 variables revealed that age and extent of pulmonary resection were significant risk factors. Despite these significant risk factors, arrhythmias after thoracic operations could be managed without special prophylaxis and were not closely related to higher mortality.