Experimental Study Of Positioning The Atrioventricular Node Rapidly In The Open Heart Surgery

Background:Accidental injury to the atrioventricular node was the main factor which lead to high-grade/complete atrioventricular block during open heart surgeries.As the atrioventricular node can't be discriminated by naked eye,we can't prevent this complication effectively at present.During our clinical practice,we found that a transient complete atrioventricular block could be induced when pressing the atrioventricular node unintentionally on a beating heart,and the conduction could return to normal after the compression was removed.According to this principle,we tried to use the“mechanical compression method”to locate the atrioventricular node during operations.Purpose:To test and verify the effectiveness of“mechanical compression method”in positioning the atrioventricular node in open heart surgeries,and lay the foundations of further animal experiments and clinical trials.Method:Ten healthy mini pigs,which was used to build the models of cardiopulmonary bypass on beating hearts and use the self-made“positioning pen”to give a moderate compression to the atrioventricular node and its surrounding areas?mechanical compression method?,according to real time ECG monitoring and observe the rhythm of heart beat directly we can judge the occurrence of complete atrioventricular block,thereby discriminate the positon of atrioventricular node.In the end,staining the myocardial tissue to make the finally positioning of the atrioventricular node,and take the result of staining as control group to verify the effectiveness of“mechanical compression method”.Result:In the ten beating heart models,none of them occurred atrioventricular block or other arrhythmia after applying mechanical compression to the non-atrioventricular node and all of them occurred complete atrioventricular block after applying mechanical compression to the atrioventricular node,one of them?P₇?still failed to recover to the normal atrioventricular conduction after the mechanical compression was removed.After staining with Lugol's iodine solution,the color of atrioventricular node turned to brownish-black,the position of atrioventricular node revealed by the“iodine solution staining method”was approximately accord with the position marked by the“mechanical compression method”.The pig?P₄?which didn't occur atrioventricular block or other arrhythmia all the time after pressing in the scheduled areas turned to be a variation in the position of atrioventricular node which was proved by the Lugol's iodine solution staining.Conclusion:In the models of pigs of cardiopulmonary bypass on beating heart,it was effective and feasible for the“mechanical compression method”to locate the atrioventricular node,and this method could lay the foundation of further clinical experimental study.