Reversible and Irreversible Damage of the Myocardium: Ischemia/Reperfusion Injury and Cardioprotection
Ischemia and reperfusion injuries can lead to major compromises in cardiac function. While the intent of many of the past cardioprotective therapies was to protect the myocardium from ischemic necrosis, it may be that reperfusion injury following ischemia
- PDF / 624,849 Bytes
- 15 Pages / 595.28 x 790.87 pts Page_size
- 72 Downloads / 158 Views
16
Brian T. Howard, Tinen L. Iles, James A. Coles Jr., Daniel C. Sigg, and Paul A. Iaizzo
Abstract
Ischemia and reperfusion injuries can lead to major compromises in cardiac function. While the intent of many of the past cardioprotective therapies was to protect the myocardium from ischemic necrosis, it may be that reperfusion injury following ischemia may occur despite such preventative attempts. There are continued efforts to identify improvements in myocardial protective strategies (pre- and postconditioning), and their ultimate goals are to minimize the risk of cellular injuries to all types of patients undergoing cardiovascular therapies, treatments, or surgeries. Keywords
Myocardial ischemia • Reperfusion injury • Cardioprotection • Myocardial stunning • Hibernating myocardium • Maimed myocardium • Ischemic preconditioning • Silent ischemia
16.1
Introduction
The goal of this chapter is to provide the reader with a general review of the physiology and pathophysiology of myocardial ischemia. In the past, it was thought that a lack of blood flow to the heart resulted in irreversible myocardial damage and necrosis (infarction). However, continued evidence has suggested that there are several identifiable clinical scenarios that present between these basic definitions of ischemia and infarction, and actually the heart may recover a variable degree of preischemic function, even when eliciting some degree of necrosis. Furthermore, with
B.T. Howard, PhD • T.L. Iles, MS (*) University of Minnesota, 420 Delaware St. SE, B172 Mayo, MMC 195, Minneapolis, MN 55455, USA e-mail: [email protected] J.A. Coles Jr., PhD Medtronic, Inc., Minneapolis, MN, USA D.C. Sigg, MD, PhD • P.A. Iaizzo, PhD Department of Surgery, University of Minnesota, Minneapolis, MN, USA
recent technological advances involving intentional cardiac arrest during cardiac surgery and noninvasive cardiac angioplasty (opening) of occluded coronary arteries, the phenomenon of reperfusion injury has also presented as a sometimes debilitating clinical syndrome. This chapter will explore these ischemic syndromes and present an up-todate overview of several methods that can be employed to protect the heart from these conditions (cardioprotection).
16.2
Basic Cardiac Metabolism
The average healthy human heart weighs between 300 and 400 g and is approximately 0.5 % of the total body mass, yet the oxygen demand of the heart accounts for 7 % of the resting body oxygen consumption and, consequently, 5 % of the cardiac output. The normal myocardial oxygen consumption (MVO2) is approximately 8 mL O2/100 g/min, yet this varies widely in normal, diseased, and/or exercising states. The MVO2 is primarily dependent on coronary blood flow (CBF) and the removal of oxygen from the coronary blood—arterial (CaO2) minus venous (coronary sinus, CSO2) contents— such that
© Springer International Publishing Switzerland 2015 P.A. Iaizzo (ed.), Handbook of Cardiac Anatomy, Physiology, and Devices, DOI 10.1007/978-3-319-19464-6_16
279
280
B.T. Howard et al.
Fig. 16.1 Influ
Data Loading...
