Cisco
CompTIA
ISC
EC-Council
EXIN
Fortinet
ITIL
Juniper
Microsoft
VMware
Avaya
SAP
Google
NVIDIA
Salesforce
Amazon
Palo Alto Networks
ISC2
Splunk
ServiceNow
All Vendors
  2. Home
  3. Exams
  4. USMLE
  5. STEP3

USMLE STEP3 Exam
Step3 (Page 29 )

Updated On: 12-Feb-2026
Page 29 of 162
PDF with 804 Questions

A 63-year-old male presents to your office with palpitations for the past 3 weeks. He has had no chest pains or dyspnea. He has no significant medical history and takes no medications. He does not smoke cigarettes and a recent lipid panel was normal. On examination, he is in no apparent distress. His pulse is 115 bpm and irregular. His BP is 125/77. His lungs are clear and his cardiac examination reveals an irregularly irregular rhythm with no murmurs, rubs, or gallops. Which of the following studies would be most appropriate to order at this time?

  1. radionuclide ventriculography
  2. exercise stress test
  3. echocardiogram
  4. cardiac catheterization
  5. electrophysiologic studies

Answer(s): C

Explanation:

Atrial fibrillation is the most common sustained clinical arrhythmia. It occurs in approximately 4% of the population over the age of 60. It is diagnosed by the presence of irregularly irregular QRS complexes on an ECG with an absence of P waves. The QRS complex is most commonly narrow, as this is a supraventricular arrhythmia. Wide QRS complexes can occur if there is an underlying conduction abnormality, such as Wolff-Parkinson-White syndrome or a bundle branch block. Saw- tooth Pwaves occur in atrial flutter, another atrial arrhythmia that may present similarly to atrial fibrillation but which is less common. The saw-tooth P waves, or flutter waves, are representative of an atrial rate typically in the range of 300350/minute.

Not infrequently, atrial flutter will lead to atrial fibrillation. Q waves in II, III, and aVF would be seen if there had been a previous inferior MI. Peaked T waves are seen in certain conditions, such as hyperkalemia, but are not routinely associated with atrial fibrillation. Atrial fibrillation may be precipitated by both cardiac and noncardiac conditions. Among the noncardiac conditions are metabolic abnormalities, which include hyperthyroidism. Of the tests listed, a suppressed TSH level, consistent with hyperthyroidism, would be most likely to be causative of atrial fibrillation. Troponin may be elevated in acute myocardial ischemia. Atrial fibrillation can occur following a MI, particularly when complicated by CHF. This is not consistent with the clinical scenario presented. Renal disease and diabetes may contribute to some of the conditions that can predispose to the development of atrial fibrillation, such as metabolic derangements or CAD. Acute and chronic pulmonary disease may also precipitate atrial fibrillation. In the setting of a man who is otherwise healthy and without significant medical history, new-onset atrial fibrillation would be less likely to be the initial presentation of diabetes, renal failure, or pulmonary disease than hyperthyroidism. For this reason, choice A is the single best answer of those provided.



A 74-year-old male with gout, osteoporosis, and type II diabetes presents for routine followup. As you review his medication list you note that he is on insulin, vitamin D, glypizide, quinidine, and allopurinol. You now diagnose him with hypertension that requires pharmacologic management. Which of the following medications would be contraindicated in this patient?

  1. enalapril
  2. hydrochlorothiazide
  3. diltiazem
  4. losartan
  5. atenolol

Answer(s): B

Explanation:

Quinidine can prolong the Q-T interval resulting in the development of polymorphic ventricular tachycardia (torsade de pointes). Hypokalemia, a side effect of thiazide diuretics, increases the risk of torsade de pointes, which can then degenerate into fatal ventricular fibrillation. Thiazide diuretics may decrease the effectiveness of uricosuric agents, insulin, and sulfonylureas and may increase the effects of vitamin D.
However, these effects tend not to be life threatening



A 60-year-old male with a history of hypertension and hyperlipidemia undergoes an evaluation for angina. He states that he routinely experiences dyspnea, fatigue, and retrosternal chest discomfort when performing activities such as walking around the block on which his house is located or climbing the flight of stairs within his home. Besides taking medications for his blood pressure and cholesterol, he uses nitroglycerin which successfully alleviates his symptoms.

Which of the following best describes the severity of this patient's angina?

  1. class I
  2. class II
  3. class III
  4. class IV
  5. Prinzmetal angina

Answer(s): C

Explanation:

Two generally accepted conventions for grading the severity of angina pectoris are those of the Canadian Cardiovascular Society (CCS) and the NYHA. The NYHA classification attempts to quantify the functional limitations imposed on an individual by their symptoms. Class I angina is defined as angina which does not appear as a patient undertakes ordinary physical activity. Symptoms caused by ordinary physical activity characterize class II angina. In class III angina, there is a moderate limitation of activity such that a patient remains comfortable at rest but symptoms appear during less-than- ordinary activities. In class IV angina, symptoms are present at rest so a patient is unable to perform any physical activity without feeling discomfort. Prinzmetal angina describes a syndrome of ischemic pain occurring at rest but not necessarily with exertion; it is diagnosed with detection of transient ST-T elevation with rest pain.

The goal of treatment of angina is to relieve symptoms and prolong exercise capacity by improving the relationship of oxygen demand and supply. Nitroglycerin is a smooth muscle relaxant that produces both venodilation (reduced preload) and arteriolar dilation (reduced afterload). Although the combined effect is to reduce myocardial oxygen demands, the potential exists for reflex tachycardia and increased contractility. To avoid the potential for increased oxygen demand and decreased coronary blood flow, a beta-blocker such as propranolol may be used concurrently with nitroglycerin. Another option is the careful titration of the nitroglycerin dose used. Discontinuation of nitroglycerin without further intervention would inappropriately leave the patient's angina pain untreated. Replacing nitroglycerin with the calcium channel blocker nifedipine may not address the problem of reflex tachycardia as nifedipine can also lead to a rapid vasodilation and subsequent drop in blood pressure (which, in turn, leads to increased sympathetic outflow and an increase in heart rate). Addition of isoproterenol would be inappropriate since it increases myocardial oxygen demand.



A 60-year-old male with a history of hypertension and hyperlipidemia undergoes an evaluation for angina. He states that he routinely experiences dyspnea, fatigue, and retrosternal chest discomfort when performing activities such as walking around the block on which his house is located or climbing the flight of stairs within his home. Besides taking medications for his blood pressure and cholesterol, he uses nitroglycerin which successfully alleviates his symptoms.
The patient states that shortly after selfadministering nitroglycerin, his heart feels like it races. He does not notice this sensation at any other times. Which of the following interventions would be most appropriate for counteracting this phenomenon?

  1. discontinue nitroglycerin
  2. increase the dose of nitroglycerin used
  3. use nifedipine instead of nitroglycerin
  4. continue nitroglycerin and start isoproterenol
  5. continue nitroglycerin and start propranolol

Answer(s): E

Explanation:

Two generally accepted conventions for grading the severity of angina pectoris are those of the Canadian Cardiovascular Society (CCS) and the NYHA. The NYHA classification attempts to quantify the functional limitations imposed on an individual by their symptoms. Class I angina is defined as angina which does not appear as a patient undertakes ordinary physical activity. Symptoms caused by ordinary physical activity characterize class II angina. In class III angina, there is a moderate limitation of activity such that a patient remains comfortable at rest but symptoms appear during less-than- ordinary activities. In class IV angina, symptoms are present at rest so a patient is unable to perform any physical activity without feeling discomfort. Prinzmetal angina describes a syndrome of ischemic pain occurring at rest but not necessarily with exertion; it is diagnosed with detection of transient ST-T elevation with rest pain.

The goal of treatment of angina is to relieve symptoms and prolong exercise capacity by improving the relationship of oxygen demand and supply. Nitroglycerin is a smooth muscle relaxant that produces both venodilation (reduced preload) and arteriolar dilation (reduced afterload). Although the combined effect is to reduce myocardial oxygen demands, the potential exists for reflex tachycardia and increased contractility. To avoid the potential for increased oxygen demand and decreased coronary blood flow, a beta-blocker such as propranolol may be used concurrently with nitroglycerin. Another option is the careful titration of the nitroglycerin dose used. Discontinuation of nitroglycerin without further intervention would inappropriately leave the patient's angina pain untreated. Replacing nitroglycerin with the calcium channel blocker nifedipine may not address the problem of reflex tachycardia as nifedipine can also lead to a rapid vasodilation and subsequent drop in blood pressure (which, in turn, leads to increased sympathetic outflow and an increase in heart rate). Addition of isoproterenol would be inappropriate since it increases myocardial oxygen demand.



A 60-year-old male with a history of hypertension and hyperlipidemia undergoes an evaluation for angina. He states that he routinely experiences dyspnea, fatigue, and retrosternal chest discomfort when performing activities such as walking around the block on which his house is located or climbing the flight of stairs within his home. Besides taking medications for his blood pressure and cholesterol, he uses nitroglycerin which successfully alleviates his symptoms.

The patient undergoes a cardiac catheterization and is found to have 70% narrowing of the left anterior descending and proximal left circumflex arteries. Which of the following would be the most appropriate management of this condition?

  1. percutaneous transluminal coronary angioplasty (PTCA)
  2. medical management with a beta-blocker, statin, and aspirin
  3. medical management with an ACE inhibitor, statin, and aspirin
  4. referral for coronary artery bypass grafting (CABG)
  5. placement of a cardiac defibrillator

Answer(s): D

Explanation:

Two generally accepted conventions for grading the severity of angina pectoris are those of the Canadian Cardiovascular Society (CCS) and the NYHA. The NYHA classification attempts to quantify the functional limitations imposed on an individual by their symptoms. Class I angina is defined as angina which does not appear as a patient undertakes ordinary physical activity. Symptoms caused by ordinary physical activity characterize class II angina. In class III angina, there is a moderate limitation of activity such that a patient remains comfortable at rest but symptoms appear during less-than- ordinary activities. In class IV angina, symptoms are present at rest so a patient is unable to perform any physical activity without feeling discomfort. Prinzmetal angina describes a syndrome of ischemic pain occurring at rest but not necessarily with exertion; it is diagnosed with detection of transient ST-T elevation with rest pain.

The goal of treatment of angina is to relieve symptoms and prolong exercise capacity by improving the relationship of oxygen demand and supply. Nitroglycerin is a smooth muscle relaxant that produces both venodilation (reduced preload) and arteriolar dilation (reduced afterload). Although the combined effect is to reduce myocardial oxygen demands, the potential exists for reflex tachycardia and increased contractility. To avoid the potential for increased oxygen demand and decreased coronary blood flow, a beta-blocker such as propranolol may be used concurrently with nitroglycerin. Another option is the careful titration of the nitroglycerin dose used. Discontinuation of nitroglycerin without further intervention would inappropriately leave the patient's angina pain untreated. Replacing nitroglycerin with the calcium channel blocker nifedipine may not address the problem of reflex tachycardia as nifedipine can also lead to a rapid vasodilation and subsequent drop in blood pressure (which, in turn, leads to increased sympathetic outflow and an increase in heart rate). Addition of isoproterenol would be inappropriate since it increases myocardial oxygen demand.






Post your Comments and Discuss USMLE STEP3 exam prep with other Community members:

Join the STEP3 Discussion