the terms  stunned myocardium  and  hibernating myocardium  refer to abnormality in the systolic and diastolic function of the heart following reperfusion.1 in both abnormalities , myocardial contractility and relaxation are deteriorated , while the cardiac enzymes are still viable.2 in the hibernating myocardium , however , a programmed cell death ( apoptosis ) pattern has been described .
myocardial ischemia results in the utilization of adenosine triphosphate atp stores secondary to the paralysis of aerobic metabolism and oxidative phosphorylation.3 stunning was defined by braunwald as post - ischemic cardiac dysfunction of viable myocardium.4 clinical myocardial stunning was first reported by bolli and klonar , who separately characterized its experimental models .
stunning has been documented in post - percutaneous coronary intervention and thrombolytic therapy for coronary artery stenosis5 , 6 and also in the wake of cardiopulmonary bypass ( cpb).6 , 7 one of the technical challenges in off - pump coronary artery bypass grafting surgery ( opcab ) is myocardial ischemia caused by the proximal and distal snaring of the coronary artery , which gives rise to post - ischemic ventricular dysfunction.8 nonetheless , the occurrence of myocardial stunning in this setting has yet to be fully investigated .
we herein report the case of a patient who developed temporary left ventricular dysfunction after an opcab procedure .
a 53-year - old man presented with unstable angina due to the severe stenosis of the left anterior descending coronary artery and obtuse marginalis , although the right coronary artery was normal .
laboratory findings , including a complete blood count , erythrocyte sedimentation rate , and c reactive protein , were normal .
chest x - ray revealed no abnormal findings , and there was no valvular abnormality on preoperative echocardiography .
the patient had no co - morbid disorders , but his left ventricular ejection fraction was reduced ( 4045% ) .
, there was no respiratory distress , blood pressure was 130/80 mm hg , heart rate was 80 beats per minute , respiratory rate was 23 per minute , the neck veins were not distended , and there was no ankle edema .
cardiovascular system examination showed regular first and second heart sounds with no gallop or murmur .
for temporary coronary artery occlusion , 4/0 viline sutures and a bulldog clamp were used , and warm blood was employed to de air the graft .
temporary coronary artery occlusion was not prolonged , and the electrocardiogram and hemodynamic variables and objective data showed no signs of ischemia or contractile dysfunction .
six hours later , however , he developed low cardiac output . at exploration , cardiac tamponade
there were no findings as regards pericarditis , and the patient s postoperative erythrocyte sedimentation rate , c - reactive protein , and cardiac enzymes were normal .
a high dose of adrenalin and dobutamine was administered , and an intra - aortic balloon pump was used .
intraoperative transesophageal echocardiography demonstrated a depression in the left ventricular function due to an akinetic lateral left ventricular wall in the region of the obtuse marginalis .
after hemodynamic stabilization , the patient left the intensive care unit without an intra - aortic balloon pump and inotropic support . on the fifth postoperative day ,
a coronary angiogram demonstrated patent grafts and correct anastomotic sites ( figure 1 & 2 ) . on the seventh postoperative day , the akinetic lateral wall of the left ventricle changed to dyskinesia .
finally , after hospital discharge on the thirtieth postoperative day , an echocardiogram showed a normal left ventricular function without regional wall motion abnormalities .
cpb may contribute to the mortality and cost associated with cabg.9 recently , opcab has emerged as an alternative technique allowing coronary revascularization without the need for cpb .
we have performed 300 consecutive opcab procedures in our hospital over the years . in the case
reported in this paper , the anesthesia protocol was comprised of a combination , of fentanyl and pancuronium bromide , supplemented with isoflurane and nitrous oxide , to permit early extubation .
an arterial and central venous line was utilized as is the standard in this modality .
conduits for cabg , including the left internal mammary artery and saphenous vein , were harvested in the standard fashion .
deep pericardial traction sutures were placed to facilitate elevation of the apex of the heart and exposure of the lateral wall of the myocardium .
the right pleural space was opened routinely to allow displacement of the heart to facilitate the exposure of the circumflex artery .
revascularization on the left anterior descending artery with the left internal mammary was typically performed first , followed by revascularization of the left circumflex artery and the right coronary artery distribution . to assist further in providing good presentation of the target arteries , especially the posterior and inferior walls ,
an optimal combination of pharmacological and mechanical methods was drawn upon to reduce the coronary artery movement .
stabilization of the target arteries was accomplished with an octopus stabilizer ( medtronic , ts 300 ) . intravenous heparin ( 1 mg / kg )
was given to maintain activated clotting time ( act ) between 200 and 300 seconds .
the target coronary artery was occluded proximal and distal to the proposed arteriotomy site by widely placing double - looped 4 - 0 viline sutures .
proximal anastomosis to the aorta was made on a punch aortotomy after applying a side clamp to the ascending aorta .
visualization of the anastomosis was enhanced with the use of humidified carbon dioxide blower . before the application of the octopus stabilizer , amiodarone and esmolol
were administered to the patient and communication with the anesthesia team was maintained to monitor changes in the patient s hemodynamic and to treat cardiac arrhythmias .
after distal anastomosis , proximal anastomoses were carried out on the ascending aorta with a partially occluding clamp .
serial electrocardiograms and estimation of serum creatinine phosphokinase and its mb fraction were done to detect perioperative ischemia .
ventricular dysfunction developed postoperatively in 2 patients , and 2 patients developed severe left ventricular dysfunction due to the poor quality of the anastomotic site of the left internal mammary artery to the left anterior descending coronary artery graft .
intraoperative flowmetry demonstrated normal graft flow and cardiac enzymes were not significantly elevated and postoperative angiography showed patent bypass graft and good quality of the anastomotic sites .
( figure 1 and 2 ) because the bypass grafts were patent , the only ischemic event that would have caused left ventricular dysfunction was temporary occlusion of the coronary arties .
we think that post - ischemic contractile dysfunction of the left ventricle has its pathophysiological background in myocardial stunning .
the best approach in the postoperative period is to support the acutely failing heart by inotropic drugs and intra - aortic balloon pumps .
alkholaifie reported that ultimate objective must be to prevent ventricular dysfunction by ischemic preconditioning , which could be achieved by repetitive short - time occlusion and reperfusion of the coronary vessel.9 grubitzsch did not observe segment depression or elevation after coronary artery occlusion in his patients , which usually indicates the necessity of preconditioning.8 in contrast , mulkowski , in a clinical setting of opcab , showed that transient ischemia did not limit subsequent ischemic regional dysfunction.10 this controversy in the management of post - operative left ventricular dysfunction with patent bypass graft led to this recommendation by rivetti that the use of the intra - coronary shunt must be considered if the duration of temporary coronary artery occlusion exceeds fifteen minutes .
recently , opcab has emerged as an alternative technique allowing coronary revascularization without the use of cpb . because opcab is associated with temporary myocardial ischemia
we think that the most important issue in performing opcab is the short ischemia time .
 the term  stunned myocardium  refers to abnormalities in the myocardial function following reperfusion and is common in on - pump coronary artery bypass grafting ( cabg ) and is exceedingly rare in off- pump cabg . a 53-year - old man presented with unstable angina due to the severe stenosis of the left anterior descending coronary artery ( lad ) and the obtuse marginal . 
 laboratory findings and chest x - ray revealed nothing abnormal . 
 the intraoperative course was uneventful . 
 the patient left the operating room without any inotropic support . 
 six hours later , however , he developed low cardiac output . at exploration , cardiac tamponade 
 was excluded and flowmetry showed that the graft had adequate function . 
 cardiac enzymes were normal . 
 high - dose adrenalin and dobutamine were administrated and an intra - aortic balloon pump was used . 
 after hemodynamic stabilization , the patient left the intensive care unit without an intra - aortic balloon pump and inotropic support . on the fifth postoperative day , 
 coronary angiography showed patent grafts and correct anastomotic sites . on the seventh postoperative day , 
 the akinetic lateral wall of the left ventricle changed to dyskinesia . finally after hospital discharge on the thirtieth postoperative day , 
 an echocardiogram showed normal left ventricular function without regional wall motion abnormalities . 
Introduction
Case Report
Discussion
Conclusion