Mukherjee_Interventional Cardiology Board Review, 4e

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7 Antiarrhythmics, Inotropes, Sedatives, and Lipid-Lowering Agents

achieve ROSC. Therefore, the 2020 AHA Guide lines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend the administration of either amiodarone or li docaine after initial defibrillation attempts fail to achieve ROSC. The updated guideline recom mends either amiodarone or lidocaine to im prove ROSC and survival to hospital admission, whereas prior guideline statements prioritized amiodarone use over lidocaine in pulseless ven tricular tachycardia or ventricular fibrillation. There are insufficient data to recommend pro cainamide administration during cardiac arrest. In addition, defibrillations and antiarrhythmic therapy should be prioritized over epinephrine in pulseless ventricular tachycardia or ventricu lar fibrillation, but rapid epinephrine adminis tration is appropriate during pulseless electrical activity or asystole. 7.9 Answer C. An inotrope is indicated in this pa tient with hemodynamic findings of low cardiac index combined with elevated PCWP (ie, car diogenic shock) to augment CO and improve end-organ perfusion. A preferred inotrope has not been identified in clinical studies and is frequently left to clinician preference. Due to stimulation of β -1 receptors by dobutamine with resultant increased HR and risk of cardiac ar rhythmia, milrinone is preferred in this patient following the development of ventricular fibril lation requiring defibrillation. Epinephrine is an inotropic agent, but unlike milrinone and dobutamine, it increases systemic vascular re sistance (afterload) that may be deleterious in this patient with markedly depressed left ven tricular function. Vasopressin acts through the vasopressin 1 receptors to cause vasoconstric tion and raises mean arterial pressure. It does not have any inotropic effects and causes re duction in HR and CO. Vasopressin is used as a second-line vasopressor in septic shock, but evidence for its use in cardiogenic shock is lack ing. There have been no randomized control tri als on vasopressin use in cardiogenic shock. 7.10 Answer C. Management of patients in cardio genic shock secondary to acute RV failure is fo cused on the optimization of right-sided filling pressures and reducing RV afterload. Agents that reduce preload, slow HR, or decrease contractil ity should be used with caution. Inotropes that reduce cardiac filling pressure by reducing after load—such as milrinone—are preferred. If treat ment is limited by hypotension, norepinephrine

can be added for additional support. Milrinone is more effective at reducing afterload than do butamine, and epinephrine increases afterload. Phenylephrine is a vasoconstrictor with no ino tropic properties. 7.11 Answer C. Acute hypotension in patients with HOCM should focus on maximizing preload and afterload while avoiding increases in contractil ity or HR. Phenylephrine is recommended over other agents due to its vasoconstrictive proper ties: phenylephrine is a vasoconstrictor with no positive inotropic or chronotropic properties. 7.12 Answer A. This patient is experiencing ana phylactic shock with hemodynamic compro mise. Epinephrine is the drug of choice for treating severe anaphylactic reactions. IV ad ministration provides a rapid onset of action and avoids erratic absorption from subcutane ous sites. IV administration is typically reserved for patients experiencing shock. Additional supportive medications—including high-dose steroids, antihistamines, histamine-2 receptor blockers, and aggressive fluid resuscitation— should be administered following the adminis tration of epinephrine. 7.13 Answer C. The patient has an elevated se rum lactate despite achieving a mean arterial pressure greater than 65 mm Hg and adequate oxygenation with mechanical ventilation. Epi nephrine may increase serum lactate via stim ulation of β -2 adrenergic receptors on skeletal muscle with increased aerobic glycolysis: the increase in lactic acid production occurs under aerobic conditions. Therefore, serum lactate may not be a consistently reliable laboratory parameter to monitor to assess end-organ per fusion during epinephrine administration. None of the other medications is a known cause of elevated serum lactate. 7.14 Answer C. According to the 2017 AHA/ACC/ HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Preven tion of Sudden Cardiac Death, atrial or ventric ular pacing or isoproterenol is recommended to increase HR to suppress recurrent TdP de spite magnesium replacement in the setting of a prolonged QTc and bradycardia (COR I, LOE B-NR). Medications that cause QTc prolongation are ineffective in suppression of TdP secondary to a prolonged QTc, so amiodarone is an inap propriate medication to suppress TdP. Although

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