Chapter 1 Cardiovascular Disorders MULTIPLE CHOICE 1.The nurse is aware that the muscle layer of the heart, which is responsible for the hearts contraction, is the: a. endocardium. b. pericardium. c. mediastinum. d. myocardium. ANS: D The myocardium is the specialized muscle layer that allows the heart to contract. 2.The nurse clarifies that the master pacemaker of the heart is the: a. left ventricle. b. atrioventricular (AV) node. c. sinoatrial (SA) node. d. bundle of His. ANS: C The SA node is the master pacemaker of the heart. 3.The nurse is aware that the symptoms of an impending myocardial infarction (MI) differ in women because acute chest pain is not present. Women are frequently misdiagnosed as having: a. hepatitis A. b. indigestion. c. urinary infection. d. menopausal complications.