Review Questions Flashcards
A 56-year-old man was admitted for a diagnostic evaluation of recent onset of chest pain. Three days before admission, he had woken up in the middle of the night with a tight precordial pain of strong intensity, lasting for 20 minutes, radiating to the upper left limb and accompanied by dyspnea, which led him to seek medical attention. The myocardial injury markers were not increased, and the ECG was not considered suggestive of acute myocardial ischemia. After receiving a prescription of atenolol and aspirin, the patient was instructed to seek the Cardiology Department for outpatient care. In the days following the initial clinical presentation, he had two new episodes with lower intensity and sought medical assistance at this Hospital. How would you classify the chest pain?
A. Stable angina.
B. Unstable angina
C. Atypical angina
A 56-year-old man was admitted for a diagnostic evaluation of recent onset of chest pain. Three days before admission, he had woken up in the middle of the night with a tight precordial pain of strong intensity, lasting for 20 minutes, radiating to the upper left limb and accompanied by dyspnea, which led him to seek medical attention. The myocardial injury markers were not increased, and the ECG was not considered suggestive of acute myocardial ischemia. After receiving a prescription of atenolol and aspirin, the patient was instructed to seek the Cardiology Department for outpatient care. In the days following the initial clinical presentation, he had two new episodes with lower intensity and sought medical assistance at this Hospital. How would you classify the chest pain?
A. Stable angina.
B. Unstable angina
C. Atypical angina
Explanation: Stable vs unstable refer to whether there is fixed pattern, trigger event and changes in quality. For this patient, the fact that there is no obvious trigger is worrisome for unstable angina. It should be noted that unstable angina often cannot be relieved with rest. Atypical angina refers to difference in the location patient experience the pain.
Learning objective:
131a State the definition, characteristics, and epidemiology of angina
At which of the following stage does platelet play a role in contributing to coronary artery disease?
A. Endothelial dysfunction
B. Foam cell formation
C. Monocyte activation
D. Plaque formation
E. Plaque rupture
At which of the following stage does platelet play a role in contributing to coronary artery disease?
A. Endothelial dysfunction
B. Foam cell formation
C. Monocyte activation
D. Plaque formation
E. Plaque rupture
Explanation: The atherosclerotic plaque formation starts from endothelial dysfunction and release of chemoattractants. Endothelial damage permits the movement of LDL-C into the subendothelial space. This LDL may then be modified (e.g. oxidized to oxLDL), which then may be taken up by macrophages, leading to the formation of foam cells, smooth muscle proliferation, and subsequent arterial plaques. The plaque may cause narrowing of the vasculature, and contribute to stable angina symptom. However, clot is not formed until the plaque is ruptured and the inside content activates tissue factor.
Learning objective:
131a Explain the interactions between platelets, clotting factors, and atherosclerotic plaques
A 64-year-old woman is evaluated in the ED 6 hours after the onset of severe crushing chest pain associated with diaphoresis, nausea, vomiting. Her medical history is significant only for hyperlipidemia; her medications are atorvastatin and aspirin. On physical exam, her BP is 140/88, and HR is 77bpm. The lungs are clear, and no cardiac murmurs are heard. Examination of the abdomen and extremities is normal. ECG shows a 3-mV ST elevation in leads II, III and aVF, with occasional premature ventricular contractions. The patient is given fibrinolytic therapy due to the inability to access a cath lab. The pain resolves, but she has two episodes of 6- to 10-beat ventricular tachycardia and stable hemodynamics parameters. ECG now shows <0.5mV ST elevation.
In addition to heparin and ASA, which of the following drug is the most appropriate next step to manage the patient?
A. Amiodarone
B. beta-blocker
C. Verapamil
D. Lidocaine
A 64-year-old woman is evaluated in the ED 6 hours after the onset of severe crushing chest pain associated with diaphoresis, nausea, vomiting. Her medical history is significant only for hyperlipidemia; her medications are atorvastatin and aspirin. On physical exam, her BP is 140/88, and HR is 77bpm. The lungs are clear, and no cardiac murmurs are heard. Examination of the abdomen and extremities is normal. ECG shows a 3-mV ST elevation in leads II, III and aVF, with occasional premature ventricular contractions. The patient is given fibrinolytic therapy due to the inability to access a cath lab. The pain resolves, but she has two episodes of 6- to 10-beat ventricular tachycardia and stable hemodynamics parameters. ECG now shows <0.5mV ST elevation.
In addition to heparin and ASA, which of the following drug is the most appropriate next step to manage the patient?
A. Amiodarone
B. beta-blocker
C. Verapamil
D. Lidocaine
Explanation: The arrhythmia patient is experiencing is most likely associated with reperfusion injury. Think about the accessory pathway, scarred tissue naturally conduct the electricity at a different rate. Usually these would not require additional medical therapy, but beta-blocker has been shown to reduce infarct size. Other drugs to consider are satin, and ACEI, especially if the patient have additional risk factors.
Learning objective:
131a Explain the role of medical therapy to reduce symptoms and improve quality of life
A 49-yr-old man is evaluated in the ED for chest discomfort accompanied by nausea and dyspnea that began 2 hr ago. On physical exam, BP is 109/78 and HR is 88bpm. There is no JVD and no carotid bruits. The lungs are clear. Cardiac exam shows normal S1 and S2, no gallops, rubs, or murmurs. Toponin is 6ng/mL (nl <0.5ng/mL). ECG shows ST elevation in lead II, III, and AVF.
He is treated with enoxaparin, ASA, metoprolol, and glycoprotein receptor blocker and is taken to the cath lab. A stent is placed into RCA. Follow-up echo shows normal wall motion, valvular function, and normal EF. By day 4, he has no complication and is ready to be discharged.
In addition to ASA, clopidogrel, and metoprolol, which of the following medication should be given at discharge?
A. Atorvastatin
B. Gemfibrozil
C. Nicacin
D. Wafarin
A 49-yr-old man is evaluated in the ED for chest discomfort accompanied by nausea and dyspnea that began 2 hr ago. On physical exam, BP is 109/78 and HR is 88bpm. There is no JVD and no carotid bruits. The lungs are clear. Cardiac exam shows normal S1 and S2, no gallops, rubs, or murmurs. Toponin is 6ng/mL (nl <0.5ng/mL). ECG shows ST elevation in lead II, III, and AVF.
He is treated with enoxaparin, ASA, metoprolol, and glycoprotein receptor blocker and is taken to the cath lab. A stent is placed into RCA. Follow-up echo shows normal wall motion, valvular function, and normal EF. By day 4, he has no complication and is ready to be discharged.
In addition to ASA, clopidogrel, and metoprolol, which of the following medication should be given at discharge?
A. Atorvastatin
B. Gemfibrozil
C. Nicacin
D. Wafarin
Explanation: For patients with previous MI histroy, statin should be maintained. He does not have additional risk factor of clotting, so there is no need to put him on anticoagulant (warfarin). If he has hyperlipidemia, fibrate should be added to reduce the risk of future cardiac event.
Learning objective:
128a Explain the pharmacologic properties of the various lipid drug classes
131a Explain the role of medical therapy to reduce symptoms and improve quality of life
134a
Inhibitors of the renin-angiotensin system are effective for blood pressure control and have beneficial effects upon endothelial dysfunction that can slow the progression of coronary artery disease and prevent atherothrombotic events such as stroke and heart attack.
A 50-year-old Caucasian male notices substernal chest pain while walking his dog uphill in Central Park on a sunny Saturday morning. The pain disappears after 5 minutes of rest, and he continues to enjoy his weekend. As he smokes a cigarette later in the day, he wonders: which of the following pathologies were most likely responsible for his chest pain that morning?
A. A fixed atherosclerotic plaque obstructing 80% of one of his coronary arteries
B. An ulcerated fibrous plaque in one of his coronary arteries
C. A pulmonary embolism
D. A ruptured atherosclerotic plaque in one of his coronary arteries
E. Weakening of aortic wall.
A 50-year-old Caucasian male notices substernal chest pain while walking his dog uphill in Central Park on a sunny Saturday morning. The pain disappears after 5 minutes of rest, and he continues to enjoy his weekend. As he smokes a cigarette later in the day, he wonders: which of the following pathologies were most likely responsible for his chest pain that morning?
A. A fixed atherosclerotic plaque obstructing 80% of one of his coronary arteries
B. An ulcerated fibrous plaque in one of his coronary arteries
C. A pulmonary embolism
D. A ruptured atherosclerotic plaque in one of his coronary arteries
E. Weakening of aortic wall.
Explanation: The patient has stable angina, which is most likely due to narrowing of coronary vessel. Ulcerated fibrous plaques are associated with unstable angina. Ruptured plaques with a fully obstructive thrombus are associated with a transmural MI.
Learning objective:
131a Explain the determinants of myocardial blood flow and how an imbalance between supply and demand can cause ischemia.
132a Describe the role of endothelial dysfunction in leading to plaque rupture and erosion
132a Explain how thrombosis requires the interaction of platelets and clotting factors
A 64-year-old male with a past medical history of obesity, diabetes, hypertension, and hyperlipidemia presents with an acute onset of nausea, vomiting, diaphoresis, and crushing substernal chest pain. Vital signs are temperature 37° C, HR 110, BP 149/87, and RR of 22 with an oxygen saturation of 99% on room air. Physical exam reveals a fourth heart sound (S4), and labs are remarkable for an elevated troponin. EKG is shown below. The pathogenesis of the condition resulting in this patient’s presentation involves:
A. Genetic inheritance of a mutation in ß-myosin or troponin expressed in cardiac myocytes
B. A fully obstructive thrombus at the site of a ruptured, ulcerated atherosclerotic plaque
C. A partially occlusive thrombus at the site of a ruptured, ulcerated atherosclerotic plaque
D. Destruction of the vasa vasorum caused by vasculitic phenomena
E. A stable atheromatous lesion without overlying thrombus
A 64-year-old male with a past medical history of obesity, diabetes, hypertension, and hyperlipidemia presents with an acute onset of nausea, vomiting, diaphoresis, and crushing substernal chest pain. Vital signs are temperature 37° C, HR 110, BP 149/87, and RR of 22 with an oxygen saturation of 99% on room air. Physical exam reveals a fourth heart sound (S4), and labs are remarkable for an elevated troponin. EKG is shown below. The pathogenesis of the condition resulting in this patient’s presentation involves:
A. Genetic inheritance of a mutation in ß-myosin or troponin expressed in cardiac myocytes
B. A fully obstructive thrombus at the site of a ruptured, ulcerated atherosclerotic plaque
C. A partially occlusive thrombus at the site of a ruptured, ulcerated atherosclerotic plaque
D. Destruction of the vasa vasorum caused by vasculitic phenomena
E. A stable atheromatous lesion without overlying thrombus
Explanation: The patient is having a STEMI (see V1-V3). This is due to complete occlusion of coronary artery either due to a thrombus or a ruptured plaque. A partially occlusive thrombus causes unstable angina, and usually do not cause ST segment change. (Note: the distinction b/w unstable angina and non-STEMI depends on the cardiac enzyme in the blood). Destruction of the vasa vasorum is associated with syphilis. A stable atheromatous lesion without overlying thrombus is usually associated with stable angina.
Learning objective:
132a Explain the various diagnostic tools to detect and quantify myocardial injury and necrosis
131a Compare the multiple techniques to diagnose ischemia
A 66-year-old gentleman presents to a new primary care physician to establish care after a recent relocation. His past medical history is significant for gout, erectile dysfunction, osteoarthritis of bilateral knees, mitral stenosis, and diabetic peripheral neuropathy. He denies any past surgeries along with the use of any tobacco, alcohol, or illicit drugs. He has no known drug allergies and cannot remember the names of the medications he is taking for his medical problems. He states that he has recently been experiencing chest pain with strenuous activities. What part of the patient’s medical history must be further probed before starting him on a nitrate for chest pain?
A .Gout
B. Erectile dysfunction
C. Arthritis
D. Mitral stenosis
E. Diabetic peripheral neuropathy
A 66-year-old gentleman presents to a new primary care physician to establish care after a recent relocation. His past medical history is significant for gout, erectile dysfunction, osteoarthritis of bilateral knees, mitral stenosis, and diabetic peripheral neuropathy. He denies any past surgeries along with the use of any tobacco, alcohol, or illicit drugs. He has no known drug allergies and cannot remember the names of the medications he is taking for his medical problems. He states that he has recently been experiencing chest pain with strenuous activities. What part of the patient’s medical history must be further probed before starting him on a nitrate for chest pain?
A .Gout
B. Erectile dysfunction
C. Arthritis
D. Mitral stenosis
E. Diabetic peripheral neuropathy
Explanation: Nitrate is contraindicated if the patient is simultaneously taking phosphodiesterase inhibitors (eg. Viagra).
Learning objective:
134a Predict the effects of anti-ischemic drugs on heart rate, blood pressure, myocardial inotropy, and coronary blood flow
A 55-year-old male is started on nitrate therapy for treatment of stable angina. He experiences significant and immediate relief of his symptoms within minutes of starting therapy. Approximately 48 hours after initiating this new medication, he notes return of chest pain and pressure with exertion that no longer responds to continued nitrate use. Which of the following regimen could explain the patient’s symptom?
A. Transdermal nitroglycerin patch placed at 7am then replaced with another at 7pm
B. Transdermal nitroglycerin patch placed at bedtime and removed at 7am
C. Transdermal nitroglycerin patch placed at 7am and removed at night
D. PO extended release isosorbide-5-mononitrate once daily at 8am
A 55-year-old male is started on nitrate therapy for treatment of stable angina. He experiences significant and immediate relief of his symptoms within minutes of starting therapy. Approximately 48 hours after initiating this new medication, he notes return of chest pain and pressure with exertion that no longer responds to continued nitrate use. Which of the following regimen could explain the patient’s symptom?
A. Transdermal nitroglycerin patch placed at 7am then replaced with another at 7pm
B. Transdermal nitroglycerin patch placed at bedtime and removed at 7am
C. Transdermal nitroglycerin patch placed at 7am and removed at night
D. PO extended release isosorbide-5-mononitrate once daily at 8am
Explanation: The patient likely is experience tolerance to nitrate becsauase he does not have sufficient nitrate free period (at least 8hr is needed). The regimen in B is good for night-time angina and C is good for angina associated with activities.
Learning objective:
134a Predict the effects of anti-ischemic drugs on heart rate, blood pressure, myocardial inotropy, and coronary blood flow
29-year-old woman is evaluated in the ED at 30 weeks gestation for increasing DOE. On physical exam, BP is 110/80 and HR is 98bpm regular. Bilateral crackles are heard. Cardiac exam shows a normal S1, a fixed split S2, a grade 2/6 early systolic murmur at the base, and grade 2/6 holo systolic murmur a the apex radiating to the axila. Echo shows global LV hypokinesis, 30% EF and moderate mitral regurgitation. Peripartum cardiomyopathy and HF are diagnosed. Which of the following HF medication is contraindicated:
A. Atenolol
B. Furosemide
C. Isosorbide dinitrate
D. Lisinopril
29-year-old woman is evaluated in the ED at 30 weeks gestation for increasing DOE. On physical exam, BP is 110/80 and HR is 98bpm regular. Bilateral crackles are heard. Cardiac exam shows a normal S1, a fixed split S2, a grade 2/6 early systolic murmur at the base, and grade 2/6 holo systolic murmur a the apex radiating to the axila. Echo shows global LV hypokinesis, 30% EF and moderate mitral regurgitation. Peripartum cardiomyopathy and HF are diagnosed. Which of the following HF medication is contraindicated:
A. Atenolol
B. Furosemide
C. Isosorbide dinitrate
D. Lisinopril
Explanation: ARB and ACE-inhibitor are associated with fetal renal agenesis and should be avoided in pregnancy. Exposure in second and third trimester exposure are related to impaired fetal/neonatal renal function, which results in oligohydramnios during pregnancy (amniotic fluid is largely derived from the fetal kidneys), and anuria and renal failure after delivery.
Learning objective
Describe the different physiologic mechanisms that contribute to blood pressure
Which of the following is true regarding the use of protamine sulfate?
A. More effective for reversing LMW heparin compared to unfractionated heparin
B. No effect on action of direct thrombin inhibitors
C. Mechanism is based on highly negative protamine charge
D. Check INR within 4hrs: should drop to <2 to resolve bleed
Which of the following is true regarding the use of protamine sulfate?
A. More effective for reversing LMW heparin compared to unfractionated heparin
B. No effect on action of direct thrombin inhibitors
C. Mechanism is based on highly negative protamine charge
D. Check INR within 4hrs: should drop to <2 to resolve bleed
Explanation: Protamine sulfate binds to heparin due to its positive charge. It has greater effect on undractionated heparin. Reversal of heparin would lead to normalization of PTT (note that heparin inhibits both thrombin and factor Xa).
Learning objective:
Anticoagulation therapy:
Review the various classes of anticoagulants (vitamin K antagonists, heparins, direct factor Xa and thrombin inhibitors) and their loci of action.
Explain how direct factor Xa and thrombin inhibitors differ from warfarin, and why they are replacing warfarin in clinical practice
You are in the ED seeing a 60-year-old patient with AVNRT with underlying atrial flutter discovered during his annual physical exam in his primary care physician’s office. The medical history is significant for type II diabetes, hypertension and heart failure with reduced ejection fraction. After discussing with the patient, you decide to start the patient on rate control medication. Which of the following drug can be used as rate control medication but should NOT be given to this patient?
A. Verapamil
B. Lebetalol
C. Procainamide
D. Ibutilide
You are in the ED seeing a 60-year-old patient with AVNRT with underlying atrial flutter discovered during his annual physical exam in his primary care physician’s office. The medical history is significant for type II diabetes, hypertension and heart failure with reduced ejection fraction. After discussing with the patient, you decide to start the patient on rate control medication. Which of the following drug can be used as rate control medication but should NOT be given to this patient?
A. Verapamil
B. Lebetalol
C. Procainamide
D. Ibutilide
Explanation: All of the drugs are good antiarrhythmic agents. However, centrally acting calcium channel blocker is contraindicated in patients with heart failure.
Learning objective:
Pharmacology of anti-hypertensives
144a Describe which drugs and classes of drugs are useful for the arrhythmias discussed in this lecture
A 50-year-old man presents to the emergency department because of substernal chest pain that started 4 hours ago and is becoming severe. After a thorough work-up he is diagnosed with an acute myocardial infarction. Which of the following laboratory test elevations is most specific for MI?
A. Alanine aminotransferase (ALT)
B. Aspartate aminotransferase (AST)
C. Creatine kinase-MB fraction (CK-MB)
D. Lactate dehydrogenase (LDH)
E. Troponin I
A 50-year-old man presents to the emergency department because of substernal chest pain that started 4 hours ago and is becoming severe. After a thorough work-up he is diagnosed with an acute myocardial infarction. Which of the following laboratory test elevations is most specific for MI?
A. Alanine aminotransferase (ALT)
B. Aspartate aminotransferase (AST)
C. Creatine kinase-MB fraction (CK-MB)
D. Lactate dehydrogenase (LDH)
E. Troponin I
Explanation:
A. Mostly in liver.
B. Liver, heart, and sk. Muscle
C. Troponin is more specific and equally (if not more) sensitive than CK-MB
D. LDH is a good marker for liver disease, MI, hemolysis but is not specific
E. Troponin is a protein found along the sarcomeres that assist in muscle contraction. With muscle injury, troponin is leaked into the serum. Different fractions show different specificities for different tissues. In cardiac tissue, troponin I has been shown to be more specific and equally if not more sensitive than cardiac enzymes, CK-MB in particular.
Learning objectives:
130a Define the laboratory tests to confirm the diagnosis of MI
131a Compare the multiple techniques to diagnose ischemia
A 22-year-old man is evaluated in the ED for rapid heart rate and lightheadedness. HE reports episodes of a “racing heart” a few times each year since his early teens. He escribes today’s episode as different: It started as one of his regular episodes but then become erratic. In addition, the lightheadedness has never happened before. He is otherwise healthy and takes no medications.
On physical exam, the patient is diaphoretic. BP is 72mm/palp. His lungs are clear, and cardiac examination demonstrates a rapid irregular rhythm with no murmurs. ECG is shown:
Which of the following is the most appropriate therapy for this patient:
A. D-C cardioversion
B. IV procainamide
C. IV verapamil
D. overdrive atrial pacing
A 22-year-old man is evaluated in the ED for rapid heart rate and lightheadedness. HE reports episodes of a “racing heart” a few times each year since his early teens. He escribes today’s episode as different: It started as one of his regular episodes but then become erratic. In addition, the lightheadedness has never happened before. He is otherwise healthy and takes no medications.
On physical exam, the patient is diaphoretic. BP is 72mm/palp. His lungs are clear, and cardiac examination demonstrates a rapid irregular rhythm with no murmurs. ECG is shown:
Which of the following is the most appropriate therapy for this patient:
A. D-C cardioversion
B. IV procainamide
C. IV verapamil
D. overdrive atrial pacing
Explanation: The patient is having A fib with an accessary pathway. Note the variable QRS complex width and irregularity. In case of structural abnormality, NEVER use drugs that target AV node. Prodcainamide is an option if the patient is hemmodynamically stable. However, the blood pressure suggest that the patient have issue maintaining cardiac output, so D-C cardioversion is preferred.
Learning objective:
144a Describe the major clinical uses of each of the drugs covered within this lecture
141a Describe the mechanisms and basic clinical features and management of paroxysmal supraventricular tachycardia, atrial fibrillation and flutter.
A 63-year-old man with a history of hypertension and atrial fibrillation is brought into the emergency room and found to have a ventricular tachyarrhythmia. Initially, family member reported no history of any cardiac disease. Therefore, you started the patient on ibutilide. While you are interviewing family member to figure out if anything that is missed, a code alarm went off. You rush to the bed side and saw the following ECG:
Which of the following could explain the patient’s episode?
A. Presence of an accessory conductive pathway
B. Mutation in potassium channel
C. Patent foramen ovale
D. Pulmonary hypertension
E. Vegetation on mitral valve
A 63-year-old man with a history of hypertension and atrial fibrillation is brought into the emergency room and found to have a ventricular tachyarrhythmia. Initially, family member reported no history of any cardiac disease. Therefore, you started the patient on ibutilide. While you are interviewing family member to figure out if anything that is missed, a code alarm went off. You rush to the bed side and saw the following ECG:
Which of the following could explain the patient’s episode?
A. Presence of an accessory conductive pathway
B. Mutation in potassium channel
C. Patent foramen ovale
D. Pulmonary hypertension
E. Vegetation on mitral valve
Explanation: The patient is experience Torsade de pointe, and long QT syndrome is a potential underlying cause.
Learning objective:
141a Compare and contrast Ventricular tachycardia as a life-threatening condition with benign forms
144a Describe the major side effects of each of the drugs covered within this lecture
A 63-year-old man with a history of hypertension and atrial fibrillation is brought into the emergency room and found to have a ventricular tachyarrhythmia. Initially, family member reported no history of any cardiac disease. Therefore, you started the patient on ibutilide. While you are interviewing family member to figure out if anything that is missed, a code alarm went off. You rush to the bed side and saw the following ECG:
Which of the following is not considered a proper therapy for this patient?
A. Magnesium
B. Isoproterenol
C. DC Cardioversion
D. Overdrive pacing
E. Lidocaine
A 63-year-old man with a history of hypertension and atrial fibrillation is brought into the emergency room and found to have a ventricular tachyarrhythmia. Initially, family member reported no history of any cardiac disease. Therefore, you started the patient on ibutilide. While you are interviewing family member to figure out if anything that is missed, a code alarm went off. You rush to the bed side and saw the following ECG:
Which of the following is not considered a proper therapy for this patient?
A. Magnesium
B. Isoproterenol
C. DC Cardioversion
D. Overdrive pacing
E. Lidocaine
Explanation: SHOCK if hemodynamically unstable. Goal: shortening QT to outpace the irregular rhythm. The only drug here that does not shorten the QT is lidocaine.
Learning objective:
144a Describe which drugs and classes of drugs are useful for the arrhythmias discussed in this lecture
141a Compare and contrast Ventricular tachycardia as a life-threatening condition with benign forms.
A 62-year-old man presents to the emergency department complaining of chest tightness. An electrocardiogram reveals ST segment elevation in the infero-lateral leads. He is treated for an acute myocardial infarction. His hospitalization is complicated by ectopy and several runs of non-sustained ventricular tachycardia. In an effort to reduce the risk of further arrhythmia in the post-myocardial infarction period, he is started on a Class 1 antiarrhythmic medication with very low affinity for its target channel. Which of the following images best represents the effect of the likely medication on the patient’s action potential?
A 62-year-old man presents to the emergency department complaining of chest tightness. An electrocardiogram reveals ST segment elevation in the infero-lateral leads. He is treated for an acute myocardial infarction. His hospitalization is complicated by ectopy and several runs of non-sustained ventricular tachycardia. In an effort to reduce the risk of further arrhythmia in the post-myocardial infarction period, he is started on a Class 1 antiarrhythmic medication with very low affinity for its target channel. Which of the following images best represents the effect of the likely medication on the patient’s action potential?
Answer B
Explanation: The patient is receiving class Ib antiarrhythmic agent. The effect of class I antiarrthymic agent on the rate of depolarization and action potential duration are shown below:
Rate of depolarization (affinity of sodium channel) IC > IA > IB
Action potential duration IA > IC > IB (decreases)
Learning objective:
144a Recapitulate the Vaughan-Williams Classification Scheme of Antiarrhythmic Drugs
