Cardiopulmonary bypass (CPB) has improved a great deal since its first applications in the early 1950s. If improvements are to be continued, a preclinical model of CPB for small animals is desirable, mainly because of convenience of equipment and low costs. We review the different models of CPB for rats that have been designed, discuss their characteristics and points where improvements may be made. We give suggestions and requirements for a new up-to-date model that could be a useful tool in continued research on the pathophysiology and therapeutic strategies of CPB.

This study shows that the favorable results of the maze III procedure in terms of freedom from supraventricular arrhythmias persist in most patients for at least 4 years.

Different lesion sets and ablation techniques have been performed. We compared these outcomes in search of the best method. We performed a retrospective analysis of patients who have undergone AF surgery different from the maze III. The surgical lesion sets were pulmonary vein isolation (PVI) alone, left atrial maze (LAM) and bi-atrial maze (BAM) and were made with different ablation techniques. During surgery one patient died due to bleeding of a pulmonary vein. The number of patients in the PVI-, LAM-, BAM-groups was 12, 28 and 26, respectively, with freedom from AF at latest follow-up [22.0+/-15.6 (3.1-81.2) months] of 33%, 59% and 60%, respectively. Atrial flutter occurred less in the BAM-group (4%) than in the left-sided procedures (15.4%) (P=0.231). Multivariate analysis demonstrated a higher recurrence of AF for PVI alone (OR 4.42, CL 0.95-20.6, P=0.0583) and a lower recurrence for the 'cut-and-sew' technique (OR 0.13, CL 0.030-0.60, P=0.0084). Left- and bi-atrial maze procedures are equally effective in the suppression of AF, whereas omission of right-sided lesions results in a higher prevalence of atrial flutter. The 'cut-and-sew' technique is superior in terms of freedom from AF compared to bipolar and unipolar radiofrequency.

The benefits of pulsatile flow during the period of cardiopulmonary bypass (CPB) applied during open-heart surgery remains controversial. We have developed a rodent (rat) model of CBP that has been designed to functionally mimic the clinical setting, principally, but not solely, for the study of pulsatile CPB. The successful development of this model centres on the design of the bypass circuitry and the surgical approach employed. The entire circuit is similar to clinical equipment in terms of its construction, configuration, performance, material surface area to blood volume ratio, and priming volume to blood volume ratio. The overall priming volume of the perfusion circuitry is less than 12 ml. Early studies confirm that the pumping technology functions well, gas exchange was adequate at all times, and blood pressure exhibited a normal CPB profile and haemodynanmic response to pulsatile blood flow. We conclude that this is an effective tool for investigating the pathophysiology of pulsatile blood flow during CPB.

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