USMLE STEP 1 CARDIOLOGY REVIEW

EMBRYO/ANATOMY

PHYSIOLOGY

PATHOPHYS-1

PATHOPHYS-2

PHARM

100

A 55-year-old man comes to the emergency department because of left-sided chest pain and difficulty breathing for the past 30 minutes. His pulse is 88/min. He is pale and anxious. Serum studies show increased cardiac enzymes. An ECG shows ST-elevations in leads I, aVL, and V5-V6. A percutaneous coronary intervention is performed. In order to localize the site of the lesion, the catheter must pass through which of the following structures?

(a) Posterior coronary sinus --> L circumflex art.

(b) L coronary main --> L circumflex artery

(d) L coronary main --> posterior descending artery

(e) L coronary main --> L ant. descending

(b) L coronary main --> L circumflex

I, aVL = lateral leads

V5, V6 = lateral, anterior precordial leads

LCX supplies the posterior walls of the LV and anterolateral papillary wall muscle.

100

A 72-year-old woman is admitted to the hospital for treatment of unstable angina. Cardiac catheterization shows occlusion that has caused a 50% reduction in the diameter of the left circumflex artery. Resistance to blood flow in this vessel has increased by what factor relative to a vessel with no occlusion?

(a) 64

(b) 16

(d) 4

(b) 16.

Poiseulle relationship:

Resistance ~ 1/radius^4

100

A 73-year-old man with coronary artery disease and hypertension is brought to the emergency department by ambulance 90 minutes after the acute onset of substernal chest pain and dyspnea. He has smoked 2 packs of cigarettes daily for 52 years. Shortly after arriving at the hospital, he loses consciousness and is pulseless. Despite attempts at cardiopulmonary resuscitation, he dies. Examination of the heart at autopsy shows complete occlusion of the left anterior descending artery with a red thrombus overlying a necrotic plaque. Which of the following pathophysiologic mechanisms is most likely responsible for this patient's coronary occlusion?

(a) Stasis of blood flow

(b) Influx of lipids into the endothelium

(d) Release of platelet-derived growth factor

(e) Migration of macrophages into the tunica intima

(b) Secretion of MMPs.

Atherosclerosis.

Endothelial dysfunction/damage --> migration of monocytes/macrophages into the endothelium --> followed by migration of LDL, oxidized, forms foam cells, atheroma formation (plaque). Plaque rupture (unstable plaque) due to inflammation, leading to macrophage-mediated release of MMPs which degrade the plaque.

100

A 71-year-old man with hypertension is taken to the emergency department after the sudden onset of stabbing abdominal pain that radiates to the back. He has smoked 1 pack of cigarettes daily for 20 years. His pulse is 120/min and thready, respirations are 18/min, and blood pressure is 82/54 mm Hg. Physical examination shows a periumbilical, pulsatile mass and abdominal bruit. There is epigastric tenderness. Which of the following is the most likely underlying cause of this patient's current condition?

(a) Coronary artery narrowing

(b) Aortic wall stress

(d) Gastric mucosal ulceration

(e) Portal vein stasis

(b) Aortic wall stress.

AAA, rupture.

Radiation to the back.

RFs (classic): age, male, smoker, HTN.

Pulsatile abd mass.

100

A 50-year-old man comes to the physician because of swelling of his legs for 2 months. Three months ago, he was diagnosed with hypertension and started on a new medication. His blood pressure is 145/95 mm Hg. Physical examination shows 2+ edema in both lower extremities. Laboratory studies are within the reference ranges. This patient was most likely treated with which of the following drugs?

(a) Losartan

(b) Lisinopril

(d) HCTZ

(e) Amlodipine

(e) Amlodipine.

CCB --> smooth muscle relaxation, increased hydrostatic pressure.

200

A 56-year-old man is brought to the emergency department 25 minutes after the sudden onset of severe pain in the middle of his chest. He describes the pain as tearing in quality; it radiates to his jaw. He has hypertension. He has smoked one pack of cigarettes daily for the past 25 years. Current medications include enalapril. His blood pressure is 154/95 mm Hg in his right arm and 181/105 mm Hg in his left arm. A CT scan of the chest is shown. The structure that is damaged in this patient is a derivative of which of the following?

(a) Truncus arteriosus

(b) R common cardinal vein

(d) Primitive atrium

(e) R horn of sinus venosus

(a) Truncus arteriosus.

Provides the pulmonary trunk and ascending aorta.

200

A 32-year-old woman comes to the physician for a screening health examination that is required for scuba diving certification. The physician asks her to perform a breathing technique: following deep inspiration, she is instructed to forcefully exhale against a closed airway and contract her abdominal muscles while different cardiovascular parameters are evaluated. Which of the following effects is most likely after 10 seconds in this position?

(a) Increased VR to R atrium

(b) Increased VR to L atrium

(d) Decreased LV stroke volume

(e) Decreased intra-abd pressure

(d) Decreased LV stroke volume.

Valsalva maneuver. Increased intra-thoracic/abd pressure compresses the IVC and aorta, leading to decreased VR and increased SVR (decreased preload, increased afterload). Both of these contribute to diminished stroke volume and cardiac output.

200

A 67-year-old woman comes to the physician for chest tightness, shortness of breath, and lightheadedness. She has experienced these symptoms during the past 2 weeks while climbing stairs but feels better when she sits down. She had a cold 2 weeks ago but has otherwise been well. She appears short of breath. Her respirations are 21/min and blood pressure is 131/85 mm Hg. On cardiovascular examination, a late systolic ejection murmur is heard best in the second right intercostal space. The lungs are clear to auscultation. Which of the following mechanisms is the most likely cause of this patient's current condition?

(a) Coronary artery lumen narrowing

(b) Transmural hypoperfusion of the myocardium

(d) Bronchiolar inflammatory constriction

Aortic stenosis --> increased afterload --> LV concentric hypertrophy --> increased myocardial O2 demand --> ischemic CP.

200

A 23-year-old man comes to the physician with a 1-week history of sharp, substernal chest pain that is worse with inspiration and relieved with leaning forward. He has also had nausea and myalgias. His father has coronary artery disease. His temperature is 37.3°C (99.1°F), pulse is 110/min, and blood pressure is 130/84 mm Hg. Cardiac examination shows a high-pitched rubbing sound between S1 and S2 that is best heard at the left sternal border. ECG shows depressed PR interval and diffuse ST elevations. Which of the following is the most likely cause of this patient’s symptoms?

(a) Dressler syndrome

(b) Acute MI

(d) SLE

(e) Viral infection

(e) Viral pericarditis.

Most common causes of acute pericarditis: Idiopathic (assumed viral).

Acute vs. chronic.

200

A 72-year-old man with coronary artery disease comes to the physician because of intermittent episodes of substernal chest pain and shortness of breath. The episodes occur only when walking up stairs and resolves after resting for a few minutes. He is a delivery man and is concerned because the chest pain has impacted his ability to work. His pulse is 98/min and blood pressure is 132/77 mm Hg. Physical examination is unremarkable. An ECG shows no abnormalities. A drug that blocks which of the following receptors is most likely to prevent future episodes of chest pain from occurring?

(a) Alpha-2 adrenergic receptors

(b) Angiotensin II receptors

(d) M2 muscarinic receptors

(e) Beta-1 adrenergic receptors

(e) Beta-blockers.

Decrease chrono- and inotropic properties, decreases myocardial O2 demand, combats angina.

300

A 3-month-old boy is brought to the physician by his mother because of poor weight gain. She also reports a dusky blue discoloration to his skin during feedings and when crying. On examination, there is a harsh, systolic murmur heard over the left upper sternal border. An x-ray of the chest is shown below. Which of the following is the most likely cause of his symptoms?

(a) Persistent connection between the aorta and pulm. artery

(b) Hypoplasia of LV

(d) RV outflow obstruction

(e) Anatomic reversal of aorta + pulm. art.

(f) Tricuspid valve regurg.

(d) RV outflow obstruction

Tetrology of Fallot:

(i) Pulm art stenosis --> pHTN

(ii) RV hypertrophy (ecc or concentric?) --> "boot-shaped heart"

(iii) VSD (murmur, where and when?)

(iv) Overriding aorta

Tet spells: Exertion causes increased shunting of blood from R to L (via VSD) to bypass stenosis, deoxygenated blood circulates systemically. Squatting increases SVR, impairs R-to-L shunting.

300

A 37-year-old woman comes to the physician for increasing shortness of breath with exercise over the past 2 months. She used to walk around her neighborhood every evening, but now has difficulty carrying out her daily activities. She has also started sleeping with three pillows at night. She remembers being hospitalized due to a serious illness during her childhood but has not seen a doctor since emigrating from Bangladesh 7 years ago. Physical examination shows crackles at the bilateral lung bases. There is an opening snap followed by a late diastolic rumble heard best at the 5th intercostal space at the midclavicular line. Which of the labeled points in the overview best corresponds to the physiologic opening time of the heart valve that is affected in this patient?

A, B, C, D, E

(E). E.

Mitral valve stenosis, rheumatic disease (Bangladesh = endemic, murmur characterization).

When does the mitral valve open? During diastole but after isovolumetric relaxation, when the pressure differential leads to mitral opening and increasing volume into the L ventricle.

300

A 60-year-old woman with ovarian cancer comes to the physician with a 5-day history of fever, chills, and dyspnea. She has a right subclavian chemoport in which she last received chemotherapy 2 weeks ago. Her temperature is 39.5°C (103.1°F), blood pressure is 110/80 mm Hg, and pulse is 115/min. Cardiopulmonary examination shows jugular venous distention and a new, soft holosystolic murmur heard best in the left parasternal region. Crackles are heard at both lung bases. Echocardiography shows a vegetation on the tricuspid valve. Peripheral blood cultures taken from this patient is most likely to show which of the following findings?

(a) G+, catalase -, alpha hemolytic, chain cocci

(b) G+, catalase+, coagulase-, clustered cocci

(d) G+, catalase-, nonhemolytic chain cocci

Staphylococcus aureus.

Discuss IE bugs and different clinical scenarios.

Discuss IE? Duke criteria (blood cultures, echo). Murmurs, acute vs subacute, etc.

300

A 32-year-old man is brought to the emergency department 10 minutes after he sustained a stab wound to the left chest just below the clavicle. On arrival, he is hypotensive with rapid and shallow breathing and appears anxious and agitated. He is intubated and mechanically ventilated. Infusion of 0.9% saline is begun. Five minutes later, his pulse is 137/min and blood pressure is 84/47 mm Hg. Examination shows a 3-cm single stab wound to the left chest at the 4th intercostal space at the midclavicular line without active external bleeding. Cardiovascular examination shows muffled heart sounds and jugular venous distention. Breath sounds are normal bilaterally. Further evaluation of this patient is most likely to show which of the following findings?

(a) 15 mmHg decrease in systolic BP during inspiration

(b) Cough productive of frank blood

(d) Sub-Q crepitus on chest wall palpation

(e) Inward collapse of chest with inspiration

(a) 15 mmHg decrease in systolic BP during inspiration.

Pulsus paradoxus. Cardiac tamponade.

>10 mmHg drop in systolic BP with inspiration.

Beck triad.

300

A 71-year-old woman comes to the physician because of dizziness and intermittent episodes of heart palpitations for 5 days. During this time, she has also had one episode of syncope. An ECG shows absence of P waves and irregular RR intervals. Treatment with an antiarrhythmic drug is initiated. The effect of the drug on the cardiac action potential is shown. Which of the following cardiac ion channels is most likely targeted by this drug?

(a) Voltage-gated nonselective cation channels

(b) Voltage-gated sodium channels

(d) Voltage-gated calcium channels

(e) Voltage-gated chloride channels

Class III anti-arrhythmics used here to inhibit voltage-gated K+ channels, prolonged repolarization, spaced out action potentials consecutively, combats tachyarrhythmias like A-fib.

Examples: Sotalol, amiodarone, dofetilide, ibutilide.

Discuss all antiarrhythmic classes?

400

A 39-year-old woman comes to the physician because of an 8-month history of progressive fatigue, shortness of breath, and palpitations. She has a history of recurrent episodes of joint pain and fever during childhood. She emigrated from India with her parents when she was 10 years old. Cardiac examination shows an opening snap followed by a late diastolic rumble, which is best heard at the fifth intercostal space in the left midclavicular line. This patient is at greatest risk for compression of which of the following structures?

(a) Trachea

(b) Thoracic duct

(d) Hemiazygos vein

(e) Esophagus

(e) Esophagus.

L atrium and esophagus anatomically APPROXIMATE each other!

Rheumatic disease (Indian = endemic, mitral stenosis ~ rheumatic disease, JONES criteria, L atrial enlargement).

Discuss Ortner's syndrome.

400

An investigator is studying the physiological factors involved in regulating coronary vessel blood flow during high metabolic activity in healthy human volunteers. In addition to the direct effects of coronary venous oxygen and carbon dioxide concentrations, the effects of adenosine, ATP-dependent potassium channels, and adrenergic activity on coronary vasodilation are examined. The volunteers undergo cardiac catheterization to measure left ventricular, left atrial, and aortic pressures. An image of the pressure tracings in one healthy volunteer is shown. Blood flow through the coronary arteries is most likely to peak at which of the following labeled points of the diagram?

A, B, C, D, E

Early diastole. Most peripheral arteries are most perfused at the point of highest systolic pressure (highest "blood pressure"). Coronary arteries are embedded into the ventricular wall, however, and are the exception. They perfuse the most during early diastole, when the ventricles relax and no longer mechanically obstruct the coronary ostiae.

400

A 46-year-old woman comes to the emergency department because of a 1-hour history of severe pain, numbness, and weakness in her right lower leg. One week ago, she had an episode of syncope that was preceded by severe palpitations. She has no history of major medical illness and takes no medications. Pulse is 110/min and irregular. Blood pressure is 124/82 mm Hg. The right leg below the knee is pale and cold to touch. Popliteal and pedal pulses are absent on the right. Which of the following is the most likely cause of the patient's symptoms?

(a) Atherosclerotic arterial narrowing

(b) Arterial vasospasm

(d) Arterial embolism

(e) Venous thrombosis

(d) Arterial embolism.

A-fib, hemostasis in L atrium (which anatomical structure?) --> thrombosis, embolism, acute limb ischemia.

Distinguish arterial vs. venous.

400

A 58-year-old man comes to the physician because of a 5-day history of progressively worsening shortness of breath and fatigue. He has smoked one pack of cigarettes daily for 30 years. His pulse is 96/min, respirations are 26/min, and blood pressure is 100/60 mm Hg. An x-ray of the chest is shown. Which of the following is the most likely cause of this patient's findings?

(a) LV failure

(b) Tricuspid regurg

(d) Idiopathic pulmonary fibrosis

(a) LV failure.

Note the Kerley B lines.

400

A 53-year-old man is brought to the emergency department because of wheezing and shortness of breath that began 1 hour after he took a new medication. Earlier in the day he was diagnosed with stable angina pectoris and prescribed a drug that irreversibly inhibits cyclooxygenase-1 and 2. He has chronic rhinosinusitis and asthma treated with inhaled β-adrenergic agonists and corticosteroids. His respirations are 26/min. Examination shows multiple small, erythematous nasal mucosal lesions. After the patient is stabilized, therapy for primary prevention of coronary artery disease should be switched to a drug with which of the following mechanisms of action?

(a) Inhibition of vitamin K epoxide reductase

(b) Blockage of P2Y12 component of ADP receptors

(d) Sequestration of calcium ions

(e) Antithrombin III potentiation

(b) Blockage of P2Y12 component of ADP receptors (anti-platelet therapy like clopidogrel/Plavix).

ASA --> Samter's triad. Remember? Multidisciplinary question.

500

A 10-year-old boy is brought to the physician by his father, who is concerned because his son has been less interested in playing soccer with him recently. They used to play every weekend, but his son has started to tire easily and has complained of pain in the lower legs while running around on the soccer field. The boy has no personal or family history of serious illness. Cardiac examination shows a systolic ejection murmur best heard over the left sternal border that radiates to the left paravertebral region. Chest x-rays show erosions of the posterior aspects of the 6th to 8th ribs. If left untreated, this patient is at greatest risk for developing which of the following?

(a) Intracranial hemorrhage

(b) Central cyanosis

(d) AAA

(e) R heart failure

(a) Intracranial hemorrhage.

Coarctation of the aorta.

- Claudication due to ischemia of tissues distal to the ductus arteriosus.

- HTN of proximal structures --> risk of intracranial hemorrhage (berry aneurysmal rupture)

- Rib notching from distended proximal aorta, mechanical stress on the bones

- Disparate BP measurements

- Associated with Turner syndrome

500

A previously healthy 26-year-old man is brought to the emergency department 30 minutes after collapsing during soccer practice. The patient appears well. His pulse is 73/min and blood pressure is 125/78 mm Hg. Cardiac examination is shown. Rapid squatting decreases the intensity of the patient's auscultation finding (systolic crescendo-decrescendo at L parasternal border). Which of the following is the most likely cause of this patient's condition?

(a) Asymmetric hypertrophy of the septum.

(b) Fibrinoid necrosis of the mitral valve.

(d) Aortic valve calcification.

(e) Aortic root dilatation.

(a) Asymmetric hypertrophy of the septum.

Hypertrophic obstructive cardiomyopathy.

Contrast aortic stenosis and HOCM.

500

A 60-year-old man comes to the emergency department because of a 2-day history of sharp chest pain and a nonproductive cough. The pain worsens with deep inspiration and improves when he leans forward. Three weeks ago, the patient was diagnosed with an ST-elevation myocardial infarction and underwent stent implantation of the right coronary artery. His temperature is 38.4°C (101.1°F) and blood pressure is 132/85 mm Hg. Cardiac auscultation shows a high-pitched scratching sound during expiration. An x-ray of the chest shows enlargement of the cardiac silhouette and a left-sided pleural effusion. Which of the following is the most likely underlying cause of this patient's current condition?

(a) Ventricular wall outpouching

(b) Occlusion of coronary artery stent

(d) L pulm art embolism

(e) Immune response to cardiac antigens

(e) Immune response to cardiac antigens.

Immune complex deposition into the pericardium, pericarditis. Know the post-MI complications and timelines!

Dressler syndrome vs. peri-infarction pericarditis.

500

DAILY DOUBLE!!!! ALL OR NOTHING:

Describe CO, PCWP, SVR, CVP in the following types of shock:

Hypovolemic, cardiogenic, obstructive, distributive (septic), distributive (neurogenic).

Discretion of host.

500

A 72-year-old man comes to the emergency department because of blurry vision for the past 3 days. He has also had 4 episodes of right-sided headaches over the past month. He has no significant past medical history. His father died of coronary artery disease at the age of 62 years. His temperature is 37.2°C (99°F), pulse is 94/min, and blood pressure is 232/128 mm Hg. Fundoscopy shows right-sided optic disc blurring and retinal hemorrhages. A medication is given immediately. Five minutes later, his pulse is 75/min and blood pressure is 190/105 mm Hg. Which of the following drugs was most likely administered?

(a) Labetalol

(b) Hydralazine

(d) Nicardipine

(e) Nitroprusside

(a) Labetalol. All can be used with HTNive emergency.

But labetalol best here for negative chronotropic effect. Others can cause reflex tachycardia.