Myocardium hibernating

Viability and Programmed Cell Survival. Perhaps the most dramatic example of chronic metabolic adaptation is the hibernating myocardium. Hibernating myocardium represents a chronically dysfunctional myocardium most likely the result of extensive... 

Residual trapping of metabolic analogues by hibernating myocardium, such as FDG [46-48], "Carbon ("Q acetate [49-52], and "C palmitate [53-55] reflects sufficient integrity of myocytes and their metabolism to allow recovery of myocardial contractile function after revascularization. 

Fig. 2.4 PET images showing hibernating myocardium with low resting perfusion but active metabolism with normal FDG uptake...

Figure 2.4 illustrates hibernating myocardium with low resting perfusion but active metabolism with normal FDG uptake in the distribution of the LCx and the diagonal branches of the LAD (perfusion-metabolism mismatch). There is scar with low perfusion and low FDG uptake in septum (perfusion-metabolism match—low perfusion and low metabolism) indicating scar. 

Figure 2.5 illustrates still another combination of metabolic states of clinical importance. There is hibernating myocardium (mismatch with low perfusion and normal metabolic FDG uptake) in the distribution of the mid LAD wrapping around the apex with scar (matched low perfusion and low metabolism—low FDG uptake) in the RCA distribution. In the distribution of the LCx and proximal LAD including the first septal perforator, the... 

Fig. 2.5 Positron emission tomography (PET) scan showing hibernating myocardium (mismatch with low perfusion and normal metabolic FDG uptake) in the distribution of the mid...

For patients with chronic CAD, nuclear imaging is essential for addressing the following major clinical issues (i) detection of ischemic myocardium, (ii) differentiation between viable hibernating or stunned myocardium and scar tissue in mechanically dysfunctional regions, and (ill) risk stratification for future major adverse events. Such information provides the basis for percutaneous coronary intervention (PCI) or coronary artery bypass (CAB) surgery and assessing their outcomes based on detection of residual ischemia and recovery of contractile function. 

Bonow RO. The hibernating myocardium implications for management of congestive heart failure. Am J Cardiol 1995 75 17A-25A... 

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Dilsizian V, Bonow RO. Current diagnostic techniques of assessing myocardial viability in patients with hibernating and stuimed myocardium. Circulation 1993 87 1-20... 

Depre C, Kim SJ, John AS, Huang Y, Rimoldi OE, Pepper JR et al. Program of cell survival underlying human and experimental hibernating myocardium. Circ Res 2004 95 433-440... 

Kamihata H, Matsubara H, Nishiue T, Fujiyama S, Amano K, Iba O, Imada T, Iwasaka T. Improvement of collateral perfusion and regional function by implantation of peripheral blood mononuclear cells into ischemic hibernating myocardium. Arterioscler Thromb Vase Ko/2002 22 1804-1810. 

At present, angiogenic therapy using bone marrow MNCs is performed worldwide in patients with treatment-resistant ischemic limbs. Moreover, angiogenic therapy using autologous bone marrow MNCs injected into stunned (hibernated) myocardium is performed in several institutions, and the number of trial centers is also increasing very fast. 

Elsasser A, Schlepper M, Klovekorn WP, Cai WJ, Zimmermann R, Muller KD, et al. Hibernating myocardium An incomplete adaptation to ischemia. Circulation 1997 96 2920-2931. 

Salient features of the hibernating myocardium are the increase in glucose uptake out of proportion to coronary flow (metabolism/perfusion mismatch)81 and the increase in myocardial glycogen content with ultrastructural characteristics resembling those of the fetal heart.82... 

C.S. Baker, D.P. Dutka, D. Pagano, O. Rimoldi, M. Pitt, R.J. Hall, J.M. Polak, R.S. Bonserand P.G. Camici, Immunocytochemical evidence for inducible nitric oxide synthase and cyclooxygenase-2 expression with nitrotyrosine formation in human hibernating myocardium, Basic Res Cardiol 97(5), 409-415 (2002). 

D.K. Kalra, X. Zhu, M.K. Ramchandani, G. Lawric, M.J. Reardon, D. Lee-Jackson, W.L. Winters, N. Sivasubramanian, D.L. Mann and W.A. Zoghbi, Increased myocardial gene expression of tumor necrosis factor-alpha and nitric oxide synthase-2 a potential mechanism for depressed myocardial function in hibernating myocardium in humans, Circulation 105(13), 1537-1540 (2002). 

J.M. Canty, G. Suzuki Jr, M.D. Banas, F. Verheyen, M. Borgers J.A. Fallavollita, Hibernating myocardium chronically adapted to ischemia but vulnerable to sudden death, Circ. Res. 94,507-516 (2004). 

In contrast, a stepwise infusion of dobutamine starting at a lower dose (i.e., 2.5 mcg/kg/min) has been used to help identify hibernating myocardium in patients... 

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