Review Session Questions

9. A 73-year-old man presents to his primary care physician with chest pain. He noticed the pain after walking several blocks, and the pain is relieved by sitting. On exam, he has a BP 155/89 mmHg, HR 79 bpm, and T 98.9 F. The physician refers the patient to a cardiologist and offers prescriptions for carvedilol and nitroglycerin. Which of the following describes the mechanism or effects of each of these medications, respectively? A. Increased cAMP; increased cAMP B. Increased contractility; decreased endothelial nitrous oxide C. Decreased cAMP; increased cGMP D. Decreased cGMP; increased venous resistance E. Increased HR; decreased arterial resistance

C. Carvedilol is a beta blocker that exerts an effect via decreasing cAMP. Nitroglycerin is a nitrate that exerts an effect via increasing cGMP. Beta blockers, nitrates, and calcium channel blockers are commonly-prescribed, antianginal medications. Beta blockers decrease cAMP levels, which lead to decreased contractility, heart rate, blood pressure, and myocardial oxygen consumption. Nitrates increase cGMP levels, which lead to dilation of veins and arteries, with venous dilation more significant than arterial dilation. This leads to decreased preload, left ventricular end-diastolic pressure, and myocardial oxygen consumption. Calcium channel blockers inhibit voltage-gated L-type calcium channels, which lead to decreased contractility, sinoatrial node conduction, and myocardial oxygen consumption.

2. A 60-year-old African American gentleman presents to the emergency department with sudden onset "vice-like" chest pain, diaphoresis, and pain radiating to his left shoulder. He has ST elevations on his EKG and elevated cardiac enzymes. Concerning his current pathophysiology, which of the following changes would you expect to see in this patient? A. No change in CO, increased SVR B. No change in CO, decreased VR C. Decreased CO, increased SVR D. Decreased CO, decreased VR E. Increased CO, increased SVR

C. This patient presents with chest pain, EKG, and lab findings consistent with an acute myocardial infarction (MI). An acute MI will result in a loss of cardiac contractility with a resulting drop in cardiac output (CO) and a reflexive increase in systemic vascular resistance (SVR). Myocardial infarctions generally cause a decrease in CO secondary to a loss of function of an area of myocardium. The drop in blood pressure is detected by baroreceptors in the aortic and carotid bodies, resulting in decreased vagal tone. Simultaneously, the drop also results in a medullary response to increase vascular tone. These responses represent the hallmark of cardiogenic shock, mainly a drop in CO (pump failure) and a reflexive increase in SVR. An acute myocardial infarction will result in a drop in cardiac output (CO) and a reflexive increase in systemic vascular resistance (SVR).

11. A 27-year-old woman presents to her primary care physician complaining that she has recently been experiencing vague chest discomfort. Physical examination reveals a mid-systolic click that is thought to be due to sudden tensing of chorda tendinae. How would this murmur be enhanced while listening on examination and what confirmatory test should be done? A. Inspiration, EKG B. Inspiration, Echo C. Squatting, Echo D. Valsalva, Echo E. Hand Grip, EKG

D.

8. A 27-year-old male arrives in the emergency department with a stab wound over the precordial chest wall. The patient is in distress and is cold, sweaty, and pale. Initial physical examination is significant for muffled heart sounds, distended neck veins, and a 3 cm stab wound near the left sternal border. Breath sounds are present bilaterally without evidence of tracheal deviation. Which of the following additional findings would be expected on further evaluation? A. Decrease in Pt HR by 15 beats per minute with inspiration B. Elevated BP to 170/110 C. Steadily decreasing HR to 60 beats per minute D. 15 mmHg decrease in systolic blood pressure with inspiration E. Decrease in central venous pressure by 5 mmHg with inspiration

D. This patient's presentation is consistent with a diagnosis of pericardial tamponade. Pulsus paradoxus is a sign commonly associated with cardiac tamponade and is defined as a decrease in systolic blood pressure of greater than 10 mmHg with inspiration. Cardiac tamponade is classically associated with Beck's triad of signs: 1) hypotension, 2) jugular venous distension, and 3) muffled heart sounds. In addition, pulsus paradoxus is seen in acute cardiac tamponade, as well as in constrictive pericarditis, severe obstructive lung disease, or restrictive cardiomyopathy. In the absence of any pathology, there is normally a fall in blood pressure of less than 10 mmHg with inspiration. However, when this drop exceeds 10 mmHg in magnitude, it is referred to as pulsus paradoxus. In a normal heart, inspiration increases systemic venous return and leads to increases in right heart volumes; expansion of the wall of the right ventricle occurs into the pericardial space without impacting left ventricular volume. However, in cases of pulsus paradoxus, the fluid-filled pericardium prevents expansion of the right ventricular wall into the pericardial space. Instead, the interventricular septum bows into the left ventricle. In turn, this leads to a decrease in left ventricular diastolic volume, which results in decreased cardiac output and therefore a decreased systolic pressure during inspiration.

4. A 29-year-old computer programmer presents to the general medicine clinic complaining of dizziness, fatigue, and shortness of breath. One month ago, the patient went on a camping trip in northern Connecticut. On assessment, vital signs are temperature 36.9°C, blood pressure 100/65, heart rate 41, and respiratory rate 16 with an oxygen saturation of 99%. A print of the EKG strip is shown below (Figure A). What is the most likely diagnosis? A. Wolff-Parkinson-White B. Mobitz I C. Mobitz II D . 1st degree block E. Complete block

E. The correct answer is third degree (complete) AV block. In this type of atrioventricular block, the atria and ventricles beat independently of each other because of disruption in the conduction pathway in the heart. Normal conduction of electricity through the heart starts at the SA node, travels to the AV node, and then to the ventricles via the bundle of His and Purkinje system. The SA node sets the heart rate because its cells have the fastest firing rate of all conductive cells (60-100 beats per minute). If there is some breach in the normal conductive pathway, other cells in the heart can set an alternative heart rate, albeit at a slower rate. In this case, the patient's symptoms can be attributed to bradycardia. Given the patient's exposure to wooded areas in the Northeast, a potential cause of this patient's block is Lyme disease. Patients with suspected Lyme carditis require hospitalization for cardiac monitoring and treatment with intravenous antibiotics such as ceftriaxone. Figure A demonstrates the characteristic EKG of third degree AV block.

6. A 60-year-old woman is found to have the following pressure vs. volume profile in her left ventricle during an analysis of her cardiac cycle. See Figure A for a comparison of her profile (in red) versus a normal profile (outlined in black). Which of the following is most likely to be appreciated on auscultation? A. Crescendo-decrescendo systolic ejection murmur B. Holosystolic, harsh-sounding murmur C. Late systolic crescendo murmur D. Continuous machine-like murmur E. Holosystolic, high pitched "blowing murmur"

E. With mitral regurgitation, regurgitation of blood from the left ventricle to the left atrium occurs throughout systole, preventing isovolumetric contraction. There is an increased preload with normal or reduced afterload. The holosystolic murmur is heard most clearly at the apex and radiates toward the axilla, and is enhanced by maneuvers that increase total peripheral resistance (e.g. squatting).

1. A 50-year-old male is seen in your clinic. Physical examination reveals a resting heart rate of 120. You perform an ECG (the reading from the V5 lead is shown in Figure A). After reviewing the ECG, you decide to start the man on a medication that primarily reduces the rate of depolarization during phase 0 and the latter part of phase 4 in cardiac slow-response tissue. What is the medication? Amlodipine Ezetimibe Adenosine Nifedipine Verapamil

Verapamil The drug used to provide rate control for this man's atrial fibrillation is verapamil, based on the mechanism of action described in the question stem. Verapamil is an L-type calcium channel blocker (CCB) that decreases calcium ion influx occurring during phase 0 and latter part of phase 4 in cardiac slow-response tissue (i.e. SA and AV nodes). CCBs are considered class IV antiarrhythmics; other antiarrhythmic classes include I (affect sodium channels), II (beta blockers), and III (affect potassium channels). Non-dihydropyridine CCBs like verapamil primarily affect cardiac tissue, unlike dihydropyridine CCBs like amlodipine and nifedipine. Figure A is an EKG strip showing the irregularly irregular ventricular response in atrial fibrillation.