1. Time Is Myocardium and the Wavefront of Necrosis
Lecture Notes
Years ago, Reimer and Jennings demonstrated that there is a wavefront of necrosis proceeding from the subendocardium to the subepicardium in a time dependent fashion. Recent data presented at the ACC from the DANAMI 2 trial raises questions as to the importance of restoring flow in a timely fashion given that patients transferred for primary PCI had good outcomes. This slide set reviews the strengths and weaknesses of the preliminary data from DANAMI 2.
CM Gibson 2002

2. Cross-sections of left ventricle after experimental
Time Dependence of Reperfusion Therapy: “Wavefront” Phenomenon of Necrosis in Dogs
Cross-sections of left ventricle after experimental
coronary artery occlusion x x x x x x x x x x x x x x x x x x x x x
Duration of occlusion
Lecture Notes
The results of studies in both animals and humans strongly support the notion that “time is muscle.”
Reimer and colleagues demonstrated that an interruption for as little as 20 to 60 minutes can result in irreversible myocardial damage. (Reimer et al, 1977)
In addition, the study demonstrated that irreversible ischemic injury occurs first in the subendocardial myocardium and extends as a wavefront toward the subepicardium during a period of 6 hours.
Significantly more necrosis was seen at 3 hours (57% ± 7%) compared with 40 minutes (38% ± 4%; P<0.05) and at 24 hours (85% ± 3%) compared with 3 hours (P<0.01). Mean infarct size at 6 hours was 71% ± 7%. (Reimer et al, 1977)
Likewise, time to the administration of fibrinolytic therapy and, subsequently, reperfusion is related to myocardial salvage. In another study of dogs, Bergmann and colleagues demonstrated that 50% of myocardium was salvaged if streptokinase was given within 90 minutes of experimentally induced occlusion, while no significant salvage was accomplished if streptokinase was administered after 6 hours. (Bergmann et al, 1982)
The fact that viable myocardium remains for as much as 6 hours has important implications for reperfusion therapy in patients with AMI.
40 min
3 h
24 h
Area supplied by
occluded artery
Necrosis
XXXX
Ischemic but viable
Nonischemic
Reimer KA, et al. Circulation. 1977;56: