PCCN Revision Questions with Explained Answers

Coronary artery perfusion is dependent upon: A. diastolic pressure B. systolic pressure C. afterload D. systemic vascular resistance (SVR) Correct Answers A. diastolic pressure Diastolic pressure in the aortic root is higher than left ventricular end-diastolic pressure (LVEDP), the pressure exerted on the ventricular muscle at the end of diastole when the ventricle is full. This enables blood to flow from a higher pressure through open arteries to a lower pressure, a pressure gradient known as coronary artery prefusion pressure. As diastolic pressure drops, there is a decrease in coronary artery blood flow. Coronary artery perfusion is not affected by systolic pressure, afterload or SVR, but they all increase the demand of oxygen in the heart. A post-STEMI (ST elevation myocardial infarction) patient is started on an angiotensin-converting enzyme (ACE) inhibitor during his hospital stay. Which of the following is the most common serious side effect that may occur? A. a nonproductive cough B. pedal edema C. swelling of the tongue and face D. rhinorrhea Correct Answers C. swelling of the tongue and face Although all of the answers may occur, swelling og the tongue and face is the most serious and may require intervention. Patients should be instructed to seek medical attention immediately for any signs of swelling in the tongue or throat. Which of the following best describes the fourth heart sound (S4): A. It occurs after ventricular contraction B. It is best heard with the diaphragm of the stethoscope C. It is a normal finding in children D. It occurs during late diastole when the atria contracts Correct Answers D. It occurs during late diastole when the atria contracts The presence of the extra heart sound S4 signifies a poorly compliant (stiff) left ventricle. An S4 is also called an atrial heart sound since it occurs at the end of diastolic filling when the atria contracts and fully fills the left ventricle. Known as "atrial kick", this filling is important to cardiac output. The increased end-diastolic volume in the ventricle improves cardiac output. When the left ventricle is stiff (decreased compliance with long term hypertension, aortic stenosis or with acute STEMI), the atrium has to pump harder to move blood from the atrium to the ventricle, causing a turbulent blood flow and extra heart sound. This heart sound is always pathologic. It occurs before ventricular contraction, is best heard with the bell of the stethoscope and is never a normal heart sound, even in children. Which pathologic changes found on the 12-lead ECG indicate myocardial ischemia? A. ST-segment elevation B. ST-segment depression and T-wave elevation C. Q-wave formation D. ST-segment depression and T-wave inversion Correct AnswersD. ST segment depression and T wave inversion Myocardial ischemia changes the repolarization of the ventricular muscle. That change is seen on the 12 lead ECG as ST-segment depression and T wave inversion, which demonstrate subendocardial ischemia -- the innermost layer of muscle in the myocardium. ST-segment elevation indicates acute injury or infarction, ST segment depression and T wave elevation may indicate an electrolyte abnormality, while Q wave formation indicates total infarction. Positive inotropic agents are used to: A. improve cardiac output and tissue perfusion B. decrease water loss through the kidneys C. increase heart rate D. vasodilate vessels Correct Answers A. improve cardiac output and tissue perfusion The term "inotropic" refers to affecting the force of myocardial contraction. Improvement of cardiac muscle contraction leads to improved cardiac output and tissue perfusion. A patient in the ED is now being admitted to telemetry bwith complaint of chest pain and has been judged to be a possible candidate for therapy with alteplase (Activase). Which of the following is not considered a contraindication for the use of this medication? A. current antibiotic use B. recent abdominal surgery C. recent gastrointestinal bleed D. recent intracranial bleed Correct Answers A. current antibiotic use Use of antibiotics is not a contraindication for the use of alteplase. All the other answers -- recent abdominal surgery, recent gastrointestinal bleeding and a recent intracranial bleed -- are contraindications for the use of any fibrinolytic. The two major components that determine blood pressure are: A. systemic vascular resistance (SVR) (afterload) and cardiac output B. contractility and SVR (afterload) C. preload and SVR (afterload) D. contractility and SVR (afterload) Correct AnswersA. SVR (afterload) and cardiac output The equation for BP is: BP = SVR x cardiac output. BP is determined by resistance of the arterial bed and the cardiac output. If the SVR (afterload) is high and the cardiac output low, the patient may still have a normal BP. the pulse pressure will be lower, but this is a compensatory response by the heart to maintain BP. If the SVR (afterload) is low (as in early septic shock), the cardiac output is very high, thereby trying to support BP. The layer of the arterial vessel wall responsible for changes in the diameter of the artery is the: A. media B. intima C. externa D. adventitia Correct AnswersA. media