Microcirculation of the Heart : Theoretical and Clinical Problems

Microcirculation is a rather new field which has been of predominant interest to basic scientists, linking togeth~r technical, hemodynamic, and biochemical aspects. The fmdings elaborated, however, are not only of theoretical interest, but bear in addition great clinical implications. In clinical cardiology this became quite evident by the use of tracers in order to study myocardial perfuSion and by the deSCription of certain clinical entities - such as angina with normal coro­ nary arteries - which are best explained by "disturbed microcirculation". With respect to this new developing theoretical and clinical field of cardiac microcirculation it was the aim of the Microcirculation Working Group of the European Society of Cardiology to have a symposium on which all different but clinically relevant aspects of cardiac microcirculation will be covered. This symposium, held in Heidelberg in January 1980, was planned not only for the exchange of concepts and ideas, but was expected to be in addition partially a teaching session; the basic scientists should be directed toward a better under­ standing of the clinical problems, and the clinicians should learn more about the basic mechanisms regulating substrate and ion exchange in such an impor­ tant organ as the heart, and furthermore the theoretical limitations of some of the diagnostic and therapeutical procedures should be taught. Without a lot of help we would never have succeeded in organizing the sym­ posium and editing its results.

A. Physiological, Biochemical and Morphological Aspects.- 1. The Arterial Wall ― Transport Properties.- Discussion.- 2. Morphology of the Myocardial Microcirculation.- Discussion.- 3. Flow Properties of the Blood.- 3.1 Flow Properties of the Blood: Erythrocytes.- 3.2 Platelets in the Haemostatic Process.- Discussion.- 3.3 Platelet Vessel Wall Interaction in Coronary Artery Disease.- Discussion.- 4. Coronary Microcirculation.- 4.1 Extravascular and Intravascular Resistance.- 4.1.1 The Effect of Increases in Cardiac Oxygen Need on Adenosine Formation and Coronary Blood Flow in the Steady State and During the Cardiac Cycle 39.- 4.1.2 Sites of Adenosine Formation in the Heart During Hypoxia.- 4.2 Flow in the Terminal Vascular Bed of the Myocardium.- 4.2.1 Methods for the Direct Evaluation of the Terminal Vascular Bed of the Yen tricular Myocardium.- 4.2.2 Pressures and Dimensions in the Terminal Vascular Bed of the Myocardium Determined by an New Free-Motion Technique.- 4.2.3 Patterns of Regional Blood Flow Following Reperfusion of Ischemic Myocardium.- Discussion.- 5. Changes in Capillary Permeability.- 5.1 Changes in Capillary Fine Structure and Function in Acute Myocardial Ischemic Injury.- Discussion.- 5.2 Microcirculatory Impairment Follwing Transient Myocardial Ischemia.- 5.3 Endothelial Diffusion Limitation of Cardiac Substrate Supply and Transport Mechanismus Supporting Substrate Exchange.- Discussion.- 5.4 Myocardial Capillary Recruitment Studied by Indicator Dilution Curves.- Discussion.- 6. Oxygen and Substrate Supply of the Myocardium.- 6.1 Oxygen.- 6.1.1 Oxygen Supply to the Myocardium.- 6.2 Substrates.- 6.2.1 Substrate Delivery in Ischemic Myocardium.- Discussion.- 6.2.2 Pyruvate Oxidation in the Hemoglobin-Free Perfused Guinea Pig Heart: Effects of Pressure, Work, and Noradrealine.- 6.2.3 Metabolic Changes in the Ischemic Myocardium. A Tool for Detection and Quantification of Ischemic Areas in the Heart?.- B. Clinical Implication of Disturbances in Coronary Microcirculation.- 1. Pathophysiology.- 1.1 Microcirculatory Determinants of Infarct Dimensions.- 1.2 The Three-Dimensional Geometry of Regional Myocardial Ischemia: The Role of the Coronary Microcirculation in Determining Patterns of Injury.- Discussion.- 2. Diagnosis ― Methods for Evaluating Myocardial Microcirculation in Patients.- Discussion.- 2.2 Assessment of Regional Myocardial Perfusion.- 2.2.1 N-13 Ammonia for the Noninvasive Evaluation of Myocardial Blood Flow by Positron Emission Computed Tomography.- Discussion.- 2.2.3 The Relationship Between Coronary Artery Disease, Myocardial Ischemia and Angina.- 2.3 Relative Regional Fractional Myocardial Oxygen Extraction in Dogs Using Oxygen-15-Water and Either Oxygen-15 Deoxyhemoglobin or Oxygen-15-0xyhemoglobin.- Discussion.- 2.4 Noninvasive Measurement of Regional Myocardial Glucose Metabolism by Positron Emission Computed Tomography.- Discussion.- 2.5 Regional Myocardial Metabolism of Free Fatty Acids.- C. Clinical Manifestations in Disturbance of Coronary Microcirculation.- 1. Small Vessel Disease.- 1.1 Morphology.- 1.1.1 Small Vessel Disease, Morphology.- Discussion.- 1.2 Clinical Diagnosis.- 1.1.2 Structural Changes of the Coronary Microcirculation Coarctation of the Aorta.- Discussion.- 1.2.1 Clinical Diagnosis of Small Vessel Disease.- 1.2.2 Coronary Hemodynamics in Systemic Arteriopathies.- Discussion.- 2. Syndrome X.- 2.1 Morphology.- 2.1.1 Morphology of Heart Muscle Cells and Myocardial Microcirculature in Patients with Angina Pectoris but Normal Coronary Arteries (Syndrome X).- 2.1.2 Studies in Patients with Abnormal Electrocardiogram of Unknown Etiology 288 288.- 2.2 Clinical Diagnosis.- 2.2.1 Reduced Coronary Reserve and Impaired Exercise Left Ventricular Performance in Patients with Syndrome X.- Discussion.- D. Therapeutic Implications.- 1. Effect of Drugs on Myocardial Microcirculation.- 1.1 The Effect of Coronary Vasodilators on the Microcirculation of the Ventricular Myocardium.- Discussion.- 1.2 Drug-Induced Changes in Myocardial Blood Flow Following Acute Coronary Artery Ligation.- 2. Rheological Aspects.- 2.1 Blood Rheology and Cardiac Microcirculation: Is There a Place for Hemodilution in Coronary Insufficiency?.- Discussion.- 2.2 Effects of Hemodilution on Myocardial Blood Flow.- Discussion.