John Stubberfield

Nitroglycerin Tolerance in Human Vessels Evidence for Impaired Nitroglycerin Bioconversion

Background—The basis for progressive attenuation of the effects of organic nitrates during long-term therapy (nitrate tolerance) remains controversial; proposed mechanisms include impaired nitrate bioconversion resulting in decreased release of nitric oxide (NO) from nitrates and/or increased NO clearance through a reaction with incrementally generated superoxide (O2–). Methods and Results—Patients undergoing elective coronary artery bypass were randomized to receive 24 hours of intravenously infused nitroglycerin (NTG; nitrate group) or no nitrate therapy (control group). Discarded segments of the internal mammary artery and saphenous vein were used to examine (1) vascular responsiveness to NTG, sodium nitroprusside, and the calcium ionophore A23187; (2) bioconversion of NTG to 1,2- and 1,3-glyceryl dinitrate; and (3) the generation of O2–. Responses to NTG were reduced 3- to 5-fold in vessels from the nitrate group compared with control vessels (P <0.01 for both types of segments), whereas responses to sodium nitroprusside and A23187 were unchanged. Tissue content of 1,2-glyceryl dinitrate was lower (P =0.012) in the saphenous veins from the nitrate group than in those from the control group. O2– generation was greater (P <0.01) in internal mammary artery samples from the nitrate group than in those from the control group. However, incremental O2– generation induced by an inhibitor of superoxide dismutase did not affect NTG responses. Conclusions—NTG tolerance in patients with coronary artery disease is nitrate-specific and is associated with evidence of impaired NTG bioconversion. Tolerance was associated with incremental O2– generation, but short-term elevation of O2– did not affect NTG responsiveness, suggesting increased NO clearance by O2– has a minimal contribution to tolerance.

Psychological Risk Factors for Increased Post-Operative Length of Hospital Stay Following Coronary Artery Bypass Graft Surgery

To date, researchers have examined the role of psychological factors in longer-term adaptation to coronary artery bypass graft surgery (CABG), but few have investigated the role of such factors in the immediate post-operative period. Thus, the current study examined psychological risk factors for increased post-operative length of hospital stay in 119 consecutive elective CABG patients (100 men and 19 women). When controlling for operative/post-operative factors, medical factors accounted for 24.5% of the variance. However, pre-operative psychological factors accounted for a further 4.4% of the variance, with increased depression and lower PTSD symptomatology identified as significant independent risk factors for longer post-operative length of hospital stay. Hence, while post-operative length of hospital stay is largely determined by medical factors, psychological factors also influence this outcome. Further research is required to replicate the current findings and to determine the mechanisms through which these variables may act.

Primary Lymphoepithelioma-Like Carcinoma of Lung

A 57-year-old Caucasian woman presented with nonproductive cough. Computed tomography revealed a peripheral solid mass in the upper lobe of the left lung. She underwent thoracotomy and upper lobectomy. Histology of the excised tumor demonstrated lymphoepithelioma-like carcinoma of the lung, with no associated Epstein-Barr virus activity. Being a rare entity and mostly seen in Asians, very few cases have been described previously.

Early results of minimally invasive mitral valve surgery: initial series in a public hospital in Australia

PurposeThis study analyzes the initial experience with minimally invasive mitral valve surgery through a right minithoracotomy in a public teaching hospital in Australia and evaluates early surgical outcomes.MethodsA retrospective review of patients who underwent minimally invasive mitral valve surgery between November 2006 and March 2009 was performed.ResultsA total of 60 patients included 47 (78%) patients who had mitral valve plasty and 13 (22%) who had mitral valve replacement. The mean age was 61 ± 15 years; 33 (55%) patients were male; and 6 (10%) had had previous cardiac operations. The mean cardiopulmonary bypass and aortic cross-clamp times were 140 ± 46 and 93 ± 35 min, respectively. All patients who underwent mitral valve plasty left the operation room with no more than trivial residual mitral regurgitation. There was no operative mortality. Reoperation for bleeding and stroke occurred in 2 patients each. The mean intensive care unit and hospital stays were 3.1 ± 5.8 and 10.6 ± 8.9 days, respectively. Among the 47 patients with mitral valve plasty, 46 (98%) had mild or less mitral regurgitation on transthoracic echocardiography at discharge. There was one late death. No reoperation for the mitral valve has been observed so far. An echocardiography report was obtained for 34 of the 47 who had had mitral valve plasty at 12.1 ± 7.9 months postoperatively, and 27 (79%) of them had mild or less mitral regurgitation.ConclusionMinimally invasive mitral valve surgery through a right minithoracotomy was safely performed with no early mortality.

Cardiac involvement in a case of acute lymphoblastic leukemia

We present an extremely rare case of an immunocompromised patient with a T-cell acute lymphocytic leukemia relapse presenting as a right atrial tumor. Problems in diagnosis, vulnerability due to previous immunosuppression and bone marrow transplant, and successful surgical excision are highlighted. Cardiac involvement with hematologic neoplasms should be taken with more than academic interest, as it may be amenable to treatment.

Chylothorax: An unusual complication following coronary artery bypass grafting using the left internal mammary artery

Abstract Development of a massive left-sided chylothorax following coronary artery grafting in a 56-year-old man is presented because of its rarity. Management with chest-tube drainage and dietary restrictions of fat with parenteral nutrition were used to treat the patient. Pleural fluid analysis for chyle in presence of massive pleural effusion was the key to early diagnosis and treatment to prevent increased morbidity and mortality. From 1985 to 1997 at this hospital, this complication occurred in 1 out of 18,978 patients who underwent coronary artery bypass graft surgery; in 6,232 patients, the left internal mammary artery was used.

Venous Cannula Obstruction by Embolus during Cardiopulmonary Bypass

During a routine mitral valve repair with coronary revascularization in a 65-year-old man, venous return was suddenly interrupted. The venous cannula was rapidly removed, revealing a large thrombus obstructing its lumen. Prompt recognition of the problem and replacement of the venous cannula resulted in uneventful recovery of the patient.