Clinical Study On Cardioprotection Of Nicorandil Preconditioning Against Ischemia/Reperfusion Injury In Patients Underwent Double Valve Replacement

Objective:To investigate whether nicorandil,a K+ATP channel opener,has cardiac protective effects in patients undergoing on-pump valve replacement, and to study the role of different drugs have different dose.Materiais and methods:Thirty patients undergoing double valva replacement surgery were randomized to the control group(Group N),nicoradil first group(Group F), nicoradil second group(Group S), every group had 10 patients,patients in Group F received 5mg nicorandil 30 minutes before anesthesia; patients in Group S received 10mg nicorandil 30 minutes before anesthesia, and patients in Group N did not receive nicoradil.Every patients were measured HR/MAP/CVP before operation (To), after open thoracic cavity (T1),30 min after cardiopulmonary bypass(T2),2h after cardiopulmonary bypass(T3),8h after cardiopulmonary bypass(T4),and 24h after cardiopulmonary bypass(T5);Arterial blood gases results and blood cTnI concentrations were tested before operation (To),pressure(CVP)were recorded at the beginning of operation(T1)immediately cardiopulmonary bypass (T1),30 min after cardiopulmonary bypass(T2),at the end of operation(T3),6h after operatin(T4),and 24h after operatin(T5).Blood CK-MB,LDH, and MDA concentrations were measured preoperatively and postoperatively. ECG and clinic index were reported.Myocardium inflammation were dectected by HE staining and examined under the light microscope.Results:1.Hemodynamic index:MAP at T1 were lower and HR were higher in Group F and Group S than that in Group N, but there had no statistic difference between groups(P>0.05).CVP at T5 were lower in Group S than that in in Group N and Group F(P<0.05). 2.ECG and arterial blood gases results:There was no significant difference about arrhythmia between three groups(P>0.05),but AVB, atrial fibrillation and ventricular arrhythmia were more when heart recovered in Group F and Group S than that in Group N. SpO2 and blood lactic acid had no statistic difference between groups at To-T3 and T5(P>0.05), but SpO2 were higher in Group S than that in Group N and Group F, while with lactic acid lower(P<0.05).3.Blood CK-MB,LDH and MDA concentration increased after the operation in both groups(P<0.05),and were lower in Group F and Group S than that in Group N(P<0.05).LDH and MDA concentration were lower in Group F than that in Group S(P<0.05).There Was no significant difference about CK-MB between Group K and Group S at other time. Blood cTnI concentration increased significantly after TO (P<0.05)in each group,and were most at T5。Blood cTnI concentration at T3-T5 were more in Group K and Group S than that in Group N(P<0.05),while also was found in Group F than in Group S (P<0.05).4.Patients had more dopamine dose in Group N than that in Group F and Group S(P<0.05),but there was no significant difference between Group K and Group S.There was no significant difference about ICU staying time and defibrillation time between three groups(P>0.05).5.Histidiagnosis by light microscope:There were more terrible about myocardium injury in Group N than that in Group F and Group S.Conclusions:Heart valve replacement surgery before the oral dose of nicorandil can promote myocardial ischemia/reperfusion functional recovery, the mechanismmay be nicorandil can open K+ channels ang diastolic coronary artert. Application of lOmg doses of nicorandil myocardial protective effect to some extent it might be better than the 5mg dose.