I. Which of the following conditions may cause myocardial ischemia?
1. Partial or total coronary obstruction.
2. An increase in myocardial demands that outpaces the supply of blood.
3. Acute falling of systemic arterial pressure leading to reduction of myocardial perfusion.
4. Reduction in the oxygen-carrying capacity of the blood.
5. Hemodilution.
6. Hypercapnia.
II. What is the most common cause of coronary occlusion?
1. Atherosclerotic narrowing of the coronary vessels.
2. Vasospasm.
3. Thromboembolism.
4. Polycythemia.
5. Microthrombosis.
6. Compression of the coronary vessels.
III. Which of the following substances induce constriction of the coronary vessels?
1. Epinephrine.
2. Thromboxane A2.
3. NO.
4. Serotonine.
5. Adenosine.
6. Lactate.
7. K+.
8. Thrombin.
IV. Myocardial ischemia develops at rest if the reduction of cross-section area of the proximal epicardial coronary artery will be:
1. Less than 60%.
2. Less than 70%.
3. Less than 75%.
4. More than 85%.
5. More than 90%.
V. Which of the following conditions may increase myocardial oxygen demands?
1. Collapse.
2. Insufficiency of the aortic valve.
3. Hypovolemic shock.
4. Severe tachycardia.
5. Acute hypertension.
6. Physical excercise.
7. Emotional stress.
8. Heart hypertrophy.
VI. Metabolic and ionic disturbances in cardiac myocytes during reversible ischemic injury are characterized by the following:
1. Increased glycolysis rate.
2. Accumulation of Na+, Cl-, Ca2+ and loss of K+.
3. An increase in intracellular pH.
4. Accumulation of creatine phosphate.
5. Accumulation of ADP and AMP.
6. Intracellular overhydration.
7. Increased protein synthesis.
VII. Which of the following intracellular changes may prevent excessive myocardial contractility during ischemia?