CCRN Practice Questions – Cardiovascular with Complete and Accurate Answers

CCRN Practice Questions – Cardiovascular with Complete and Accurate Answers A patient is in cardiac and respiratory arrest. The selection of medications to reestablish cardiac function would stimulate the sympathetic nervous system beta1 receptors. This stimulation would result in increased automaticity and which of the following? a. Increased myocardial contractility b. Decreased left ventricular stroke work c. Decreased myocardial oxygen consumption d. Increased left ventricular afterload Correct answer: a Rationale: The sympathetic nervous system contains alpha, beta, and dopaminergic receptors that produce various responses when stimulated. Stimulation of beta1 receptors increases heart rate, conductivity, and myocardial contractility. Stimulation of beta2 receptors produces vasodilation and bronchodilation. Alpha receptors, when stimulated, produce vasoconstriction. Stimulation of dopaminergic receptors produces a vasodilating effect on renal, mesenteric, coronary, and cerebral vessels. Test-Taking Strategy: Note the helpful clue in the stem: stimulate the sympathetic system and recall that this results in a fight-or-flight response—the body is responding to survive. Stroke volume would increase, so eliminate option b. Afterload would increase, but this is due to alpha stimulation, not beta1 stimulation, so eliminate option d. Because the heart is working faster and harder, the myocardial oxygen consumption does increase, so eliminate option c. Remember that the primary effects of beta1 receptors are to increase heart rate, contractility, and rate of conduction. Choose option a. A memory aid that also may help is this: beta 1 beta 2, 1 heart 2 lungs: beta1 affects the heart, and beta2 affects the lungs. A patient arrived in the emergency department with complaints of chest pain. The 12-lead electrocardiogram shows ST segment elevation in leads V3 and V4. Occlusion of the affected coronary artery most likely would affect perfusion to which portion of the conduction system? a. Sinoatrial (SA) node b. Bachmann's bundle c. Atrioventricular (AV) node d. Bundle of His Correct answer: d Rationale: ST segment elevation in leads V3 and V4 indicates injury to the anterior wall, which would occur with occlusion of the left anterior descending (LAD) artery. In most persons, the SA node, Bachmann's bundle, and AV node are supplied by the right coronary artery. The bundle of His is supplied by the left anterior descending artery. This is why an anterior myocardial infarction may cause type II second-degree AV block or third-degree AV heart block at the level of the bundle of His. Test-Taking Strategy: Note that options a, b, and c are part of the supraventricular conduction system. They usually are supplied by the right coronary artery. The LAD artery supplies most of the interventricular conduction system, including the bundle of His and the bundle branches. Oxygen delivery (DO2) is the product of which of the following? a. PaO2, hemoglobin, mean arterial pressure b. SaO2, hemoglobin, cardiac output c. SvO2,