Feasibility of a three-axis epicardial accelerometer in detecting myocardial ischemia in cardiac surgical patients.
OBJECTIVE
We investigated the feasibility of continuous detection of myocardial ischemia during cardiac surgery with a 3-axis accelerometer.


METHODS
Ten patients with significant left anterior descending coronary artery stenosis underwent off-pump coronary artery bypass grafting. A 3-axis accelerometer (11 x 14 x 5 mm) was sutured onto the left anterior descending coronary artery-perfused region of left ventricle. Twenty episodes of ischemia were studied, with 3-minute occlusion of left anterior descending coronary artery at start of surgery and 3-minute occlusion of left internal thoracic artery at end of surgery. Longitudinal, circumferential, and radial accelerations were continuously measured, with epicardial velocities calculated from the signals. During occlusion, accelerometer velocities were compared with anterior left ventricular longitudinal, circumferential, and radial strains obtained by echocardiography. Ischemia was defined by change in strain greater than 30%.


RESULTS
Ischemia was observed echocardiographically during 7 of 10 left anterior descending coronary artery occlusions but not during left internal thoracic artery occlusion. During ischemia, there were no significant electrocardiographic or hemodynamic changes, whereas large and significant changes in accelerometer circumferential peak systolic (P < .01) and isovolumic (P < .01) velocities were observed. During 13 occlusions, no ischemia was demonstrated by strain, nor was any change demonstrated by the accelerometer. A strong correlation was found between circumferential strain and accelerometer circumferential peak systolic velocity during occlusion (r = -0.76, P < .001).


CONCLUSIONS
The epicardial accelerometer detects myocardial ischemia with great accuracy. This novel technique has potential to improve monitoring of myocardial ischemia during cardiac surgery.
Halvorsen
Per Steinar
PS
The Interventional Centre, Rikshospitalet University Hospital, Oslo, Norway. per.steinar.halvorsen@rikshospitalet.no
Espinoza
Andreas
A
Fleischer
Lars Albert
LA
Elle
Ole Jakob
OJ
Hoff
Lars
L
Lundblad
Runar
R
Skulstad
Helge
H
Edvardsen
Thor
T
Ihlen
Halfdan
H
Fosse
Erik
E
D047549:Coronary Artery Bypass, Off-Pump / Q000295:instrumentation*; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000601:surgery*; D003331:Coronary Vessels / Q000601:surgery*; D004452:Echocardiography; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000601:surgery*; D006801:Humans; D017202:Myocardial Ischemia / Q000175:diagnosis*; D010496:Pericardium