The general anatomy of the cardiac conduction system (CCS) has been known for 100 years, but its complex and irregular three-dimensional (3D) geometry is not so well understood. This is largely because the conducting tissue is not distinct from the surrounding tissue by dissection. The best descriptions of its anatomy come from studies based on serial sectioning of samples taken from the appropriate areas of the heart. Low X-ray attenuation has formerly ruled out micro-computed tomography (micro-CT) as a modality to resolve internal structures of soft tissue, but incorporation of iodine, which has a high molecular weight, into those tissues enhances the differential attenuation of X-rays and allows visualisation of fine detail in embryos and skeletal muscle. Here, with the use of a iodine based contrast agent (I₂KI), we present contrast enhanced micro-CT images of cardiac tissue from rat and rabbit in which the three major subdivisions of the CCS can be differentiated from the surrounding contractile myocardium and visualised in 3D. Structures identified include the sinoatrial node (SAN) and the atrioventricular conduction axis: the penetrating bundle, His bundle, the bundle branches and the Purkinje network. Although the current findings are consistent with existing anatomical representations, the representations shown here offer superior resolution and are the first 3D representations of the CCS within a single intact mammalian heart.

Practice varies as to whether or not suction is applied to under-water seal drains following lung surgery. We tested the null hypothesis that there is no difference with respect to air leak duration. Patients undergoing thoracotomy or video assisted thoracoscopic surgery for lobectomy or wedge resection had either low-pressure suction or no suction applied to their underwater seal bottles postoperatively. Patients were allocated using minimization, a method of unbiased allocation ensuring balance between the arms of a trial with respect to known or suspected confounding factors. The trial was powered for duration of air leak. If an air leak persisted on the 7th post-operative day, the surgeon determined further management. Kaplan-Meier survival analysis of air leak duration and a log rank test were performed on an intention-to-treat basis, with observations censored at 144h (6 complete days). Of the 254 patients that entered the trial, data were available for analysis for 239 (123 no-suction and 116 suction). There was no significant difference in the cumulative persistence of air leaks between the two groups (P=0.62) and inspection of the Kaplan-Meier curves suggests that any difference is negligible. Applying suction to the underwater seal drains following lung surgery makes no difference in terms of air leak duration. In the light of this finding we have adopted a uniform policy of no suction being applied to the underwater seal, from the time of surgery, unless a specific clinical judgment is made to use it. The anticipated gains are that this will reduce work and cost and aid mobilization.

To test the hypothesis that major aorto-pulmonary collaterals (MAPCAs) have the same anatomy as bronchial arteries. Two hundred and thirty-eight angiographies performed on 61 patients with pulmonary atresia, ventricular septal defect (VSD), and MAPCAs constituted the basis for this study. This represented all available angiographies performed on this patient group at our institution during the period 1972-2001. MAPCA anatomy was compared to bronchial artery anatomy as described in previous publications. Each patient had one to five MAPCAs (mean 3.2+/-0.94). A mean of 2.6+/-0.66 MAPCAs came from the descending aorta. MAPCAs with anatomy similar to right intercosto-bronchial arteries were found in 87% of the patients. Fifty percent of the patients had MAPCAs originating from the subclavian artery regions. These numbers were all similar to those previously described for bronchial arteries. All MAPCAs had anatomy similar to bronchial arteries. The distribution in different branching patterns of MAPCAs arising from the aorta was similar to the distribution of bronchial arteries described in previous angiographic studies (p=0.32 and p=0.24). In patients with pulmonary atresia and VSD, MAPCAs are likely to be dilated bronchial arteries. Bronchial arteries may have limited growth potential and their known vasoreactivity might preclude any long-term beneficial effects of unifocalization procedures.

To investigate survival and risk factors influencing intermediate outcome after the Fontan procedure. Retrospective analysis of 122 patients operated between April 1991 and September 2002. Poor outcome was defined as late death or poor functional status (intractable supraventricular arrhythmias/NYHA 3-4) necessitating revision surgery. 64(52%) patients had an intermediate bi-directional cavo-pulmonary shunt (BCPS). 91 (76%) patients had a lateral tunnel total cavo-pulmonary connection, 21(17%) patients had an atrio-pulmonary connection and 10 (8%)patients had a Kawashima connection. There were 6 (5%)early deaths. Over a median follow up of 54 months (1-133), 12 (10%)patients have had surgical revision for poor functional status. There were 7 (6%) late deaths, 5 of which occurred after revision surgery. Univariate analysis identified older age at operation (>4 years) (P=0.04), higher postoperative pulmonary artery pressure at 24h (P=0.012), arrhythmia postoperatively (P=0.03) or during follow-up (P=0.01) and the requirement for anticoagulation during follow-up (P=0.03) as significant predictors of poorer outcome. Patients who had an intermediate BCPS (P=0.002) or Norwood Stage 1 (P=0.05) had a better outcome. Multivariate analysis identified an intermediate Glenn shunt and lower postoperative pulmonary artery pressure as significant predictors of better outcome. Actuarial freedom from death or revision is 93% (+/-2), 88% (+/-3), 86% (+/-4) and 69% (+/-7) at 1, 5, 7 and 9 years respectively. Actuarial freedom from death or revision for the lateral tunnel group is 92% (+/-2), 89% (+/-3), 85% (+/-5) and 66% (+/-10) respectively. Atrio-pulmonary connection results in a higher incidence of arrhythmias and failure than the lateral tunnel Fontan. Even in patients with a lateral tunnel Fontan there is a continuing hazard phase in the intermediate term. Mid-term outcome appears to be favorably influenced by an intermediate BCPS.