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HPl: BB is a 72-year-old man who presents to the ED with complaints of palpitations. PMH includes anterior myocar-dial infarction (Ml), hypertension (HTN), and depression.
PE: Vital signs: BP 105/75 mm Hg, HR 160 beats/min, RR 14 breaths/min. ECG showed sustained ventricular tachycardia (SuVT).
• What are the acute treatment options for SuVT?
• What is the primary pharmacology and side effects of lidocaine?
• What factors may reduce the clearance of lidocaine?
• What medications can be given orally for long-term maintenance of normal sinus rhythm in patients who have had ventricular tachycardia?
Basic Science Review and Discussion
Sustained ventricular tachycardia is defined as consecutive premature ventricular contractions lasting more than 30 seconds. Nonsustained ventricular tachycardia (VT) usually self-terminates and lasts for less than 30 seconds. The acute treatment of SuVT depends on the hemodynamic stability and symptoms of the patient. Unstable patients should receive immediate cardioversion. If patients are stable with mild symptoms, they can be treated with IV antiarrhythmics.
The antiarrhythmic of choice for SuVT is lidocaine because of its fast onset and ease of administration. Lidocaine is a class IB antiarrhythmic that inhibits sodium ion channels, decreasing the action potential duration and effective
refractory period. Lidocaine raises the electrical stimulation threshold and suppresses spontaneous depolarization of the ventricle. It is given as a bolus dose, but an additional bolus may be required 8 to 10 minutes after the first one due to the short distribution half-life. Once converted to normal sinus rhythm (NSR), the patient can be placed on a continuous infusion of lidocaine.
Side effects should be monitored after the initiation of lidocaine. The most common adverse reactions are drowsiness, dizziness, paresthesia, and euphoria. Patients also may experience serious central nervous system (CNS) side effects such as confusion, agitation, psychosis, seizures, and coma, but usually only at supratherapeutic levels. The active metabolites of lidocaine are responsible for most of the CNS toxicities. Cardiovascular side effects, including atrioventric-ular block, hypotension, and circulatory collapse, are not as well correlated to lidocaine levels.
Lidocaine is mostly cleared by hepatic metabolism. Any condition that impairs liver function or compromises liver blood flow may increase lidocaine levels. Lower infusion rates should be administered in patients with CHF, shock, advanced age, and liver cirrhosis.
Alternative intravenous antiarrhythmics that may be used for SuVT include procainamide and amiodarone. For maintenance, oral antiarrhythmics such as sotalol, procainamide, amiodarone, and quinidine are possible options.
Case Conclusion Two lidocaine boluses were given 10 minutes apart, followed by a continuous infusion. BB's VT resolved with lidocaine therapy. Upon careful review of the ECG, it was noted that he had experienced a new lateral The cardiac catherization revealed triple-vessel disease, and he underwent a coronary artery bypass graft.
Thumbnail: Oral Contraception
COCs decrease ovulation and sperm and egg transport and implantation. The estrogen component alters FSH (follicle stimulating hormone) and LH (leutinizing hormone) release, accelerates egg transport, and alters the endometrium so that it is unsuitable for implantation. Progestins alter FSH and LH release, thicken cervical mucous to reduce sperm and egg transport, inhibit enzymes necessary for fertilization, and also alter the endometrium so that it is unsuitable for implantation.
Common estrogenic side effects Estrogen excess:
Fluid retention, weight gain, edema
I breast size or tenderness
Skin discoloration (cholasma)
White or yellowish vaginal discharge
Heavy flow, hypermenorrhea
Increased risk thrombus, blood clot
BTB days 1-9 Vasomotor symptoms Nervousness, irritability Decreased libido Atrophicvaginitis
Common progestational side effects Progestin excess (also see androgenic effects):
Dysmenorrhea, amenorrhea Hypertension Candida vaginitis Breast tenderness
Androgenic side effects (excess):
T LDL, 4 HDL cholesterol
T appetite, weight gain
t acne, oily skin, hirsutism, hair loss
t depression, fatigue
BTB days 10-21 Amenorrhea Heavy flow/clots
1. RM is a 35-year-old woman who severely tore her anterior cruciate ligament (ACL) in a skiing accident and is having major surgery in 2 months, followed by an additional 2 months of bed rest and reduced mobility. She has been taking COC pills for the past 4 years. Which of the following would be good advice for RM?
A. Initiate aspririn 1 month prior to surgery.
B. Initiate warfarin 1 month prior to surgery.
C. Maintain COC use before and after the surgery.