Transmyocardial revascularization (TMR) is a new surgical procedure aimed a
t increasing blood flow to the ischemic myocardium. It has been used for tr
eatment of patients with end-stage coronary artery disease who are not cand
idates for conventional measures such as medication, percutaneous translumi
nal coronary angioplasty, and coronary artery bypass grafting. TMR involves
creating transmural channels in the myocardium using lasers, in areas show
n to be ischemic during preoperative testing. This procedure has shown prom
ising results in clinical trials, but the mechanism of its efficacy remains
largely unknown. TMR was originally developed as a means of supplying bloo
d to the ventricular myocardium, directly through channels made in the wall
of the ventricle. This was in an attempt to recreate the situation that ex
ists in the reptilian heart, in which the myocardium is perfused directly f
rom the ventricular chamber through a rich network of sinusoids that bathe
the myocardial cells. However, the existence of a significant sinusoidal ne
twork in the human heart is doubtful. Whether the myocardium can be perfuse
d directly via the TMR channels is controversial; it is becoming clear that
other mechanisms such as angiogenesis are also at work. This review will u
se TMR as an example to illustrate how surgical practice and thinking can b
e based on theories that have little or no sound experimental evidence to s
upport them. The importance of elucidating the valid scientific basis of su
rgical procedures in this modern era of evidence-based medicine will be emp
hasized.