Prediction of early postoperative atrial fibrillation after cardiac surgery: is it possible?

BACKGROUND: Postoperative atrial fibrillation is common after cardiac surgery. In this study, we aimed to investigate the value of interatrial conduction time for the prediction of early postoperative atrial fibrillation, using intra-operative transoesophageal echocardiography. METHODS: A total of 65 patients undergoing cardiac surgery in our hospital between January and March 2007 were prospectively evaluated, and 59 patients with sinus rhythm were included in the study. We performed transoesophageal echocardiography on all patients, and intra-operatively measured the interatrial conduction time, as recently described. The patients with episodes of atrial fibrillation during the postsurgery hospitalisation period were defined as group 1 and those without episodes were defined as group 2. RESULTS: Mean interatrial conduction time was 74 ± 15.9 ms in group 1 and 54 ± 7.9 ms in group 2. The difference in interatrial conduction time between the two groups was statistically significant (p < 0.05). In this study we found a statistically significant interatrial conduction delay between the groups. Postoperative atrial fibrillation was more frequent in patients with a longer interatrial conduction time. CONCLUSION: Increased interatrial conduction time may cause postoperative atrial fibrillation and it can be measured intraoperatively by transoesophageal echocardiography.

Can left internal mammary artery side branches affect blood flow rate?

The left internal mammary artery (LIMA) is the most commonly used arterial graft for coronary artery bypass graft (CABG) surgery, and occluding the LIMA side branches during surgery is important to avoid myocardial ischaemia afterwards. In this study we investigated the incidence of patent LIMA graft side branches in our coronary angiography series, and compared LIMA flow rate changes by means of the thrombolysis in myocardial infarction (TIMI) frame count in patients with and without LIMA graft side branches. Patients with a history of CABG surgery and who were scheduled for coronary angiography in our centre between 1 January and 15 December 2006 were enrolled in the study. We compared LIMA graft TIMI frame counts between patients with and without side branches. The incidence of LIMA graft side branches in our study was 18% (seven patients). Mean TIMI frame count was 27.28 +/- 3.4 in patients with LIMA graft side branches and 15.67 +/- 2.3 in patients without. There was a significant difference between the two groups (p < 0.0001). Patients with LIMA graft side branches were more likely to have anterior ischaemia, determined by myocardial perfusion scintigraphy. We suggest that TIMI frame count may be helpful in evaluating the effect of side branches on LIMA graft flow rate. The increased TIMI frame count of a LIMA graft with side branch is associated with insufficient LIMA flow.

Effect of chronic arsenic exposure from drinking waters on the QT interval and transmural dispersion of repolarization.

This study investigated the effects of chronic arsenic exposure on QT- and QTc-interval prolongation, QTc dispersion (QTcd) and transmural dispersion of repolarization (TDR). We compared cardiac parameters from 40 male subjects chronically exposed to arsenic (group A) with those of 40 male subjects not exposed to arsenic (group B). Although subjects in both groups had non-corrected QT intervals within normal limits, subjects in group A had significantly longer QTc and QTcd intervals compared with group B. A total of 70% of group A compared with 10% of group B had QTcd values > 50 ms. The mean TDR value was also significantly higher in group A compared with group B. Although non-corrected QT intervals were within normal limits, those subjects chronically exposed to arsenic had a slight QT prolongation and a higher prevalence of subtle repolarization abnormalities, which might be clinically relevant.

Acute myocardial infarction in a young man caused by centipede sting.

It is known that insects can cause various clinical effects such as myocardial ischaemia and hypotension from vasospasm and the myocardial toxic effects of the venom and anaphylaxis. Although myocardial ischaemia resulting from centipede sting has been reported once before, myocardial injury has not. In this report, the authors present the case of a 20 year old male patient bitten by a centipede and admitted to the emergency room with chest pain, abnormal electrocardiographic findings, and increased cardiac enzymes (cardiac troponin T) suggesting acute myocardial infarction.