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Zorluk: OrtaPharmacologic Interventions

A 6868-year-old woman is hospitalized for an acute exacerbation of chronic obstructive pulmonary disease (COPD). Her baseline FEV1\text{FEV}_1 is 35%35\% of predicted. Over the past 4848 hours, she has been receiving intravenous methylprednisolone, nebulized ipratropium-albuterol, and non-invasive positive pressure ventilation. On hospital day 33, her respiratory status has improved, and she is transitioned to nasal cannula oxygen. However, she begins to complain of new-onset palpitations. Vital signs show a blood pressure of 122/78 mmHg122/78 \text{ mmHg} and a heart rate of 128/min128/\text{min}. A 1212-lead electrocardiogram demonstrates an irregular rhythm with three distinct P-wave morphologies in the same lead and an irregular PR interval. Laboratory studies show a serum potassium of 4.2 mEq/L4.2 \text{ mEq/L} and a serum magnesium of 2.1 mg/dL2.1 \text{ mg/dL}. Which of the following is the most appropriate pharmacologic intervention to manage this patient's arrhythmia?

  1. A
    Adenosine
  2. B
    Amiodarone
  3. DiltiazemCevap
  4. D
    Magnesium sulfate
  5. E
    Metoprolol

Cevap

Diltiazem is the most appropriate pharmacologic intervention for this patient's arrhythmia.
The correct answer is diltiazem. This patient's electrocardiogram showing an irregular rhythm with three distinct P-wave morphologies and varying PR intervals is classic for multifocal atrial tachycardia (MAT). MAT is an abnormal automaticity rhythm most commonly seen in patients with severe pulmonary disease, particularly during an acute exacerbation of COPD. The primary treatment for MAT is optimization of the underlying pulmonary condition and correction of any electrolyte abnormalities (such as hypokalemia or hypomagnesemia). Because this patient's COPD is already being aggressively treated, her electrolytes are normal, and she remains symptomatic with a rapid ventricular rate, pharmacologic rate control is indicated. Non-dihydropyridine calcium channel blockers (such as diltiazem or verapamil) are the agents of choice. They effectively slow atrioventricular nodal conduction to decrease the heart rate and do not carry the risk of precipitating bronchospasm.

Adım Adım Çözüm

1
Interpret the electrocardiogram findings.
The presence of an irregular rhythm, irregular PR intervals, and at least three distinct P-wave morphologies is diagnostic of multifocal atrial tachycardia (MAT).
Accurate identification of the specific arrhythmia is required to select the correct mechanism of pharmacologic therapy.
2
Assess the clinical context and underlying triggers.
The patient has an acute exacerbation of severe COPD, which is the classic underlying cause of MAT. Her electrolytes (potassium and magnesium) are normal.
MAT is best managed by treating the underlying pulmonary disease and correcting electrolyte imbalances before initiating antiarrhythmics.
3
Select the most appropriate rate-controlling agent.
Because the patient remains symptomatic with tachycardia despite improving respiratory status, rate control is indicated. A non-dihydropyridine calcium channel blocker (diltiazem or verapamil) is chosen.
Non-dihydropyridine calcium channel blockers slow AV nodal conduction without causing bronchospasm, unlike beta-blockers or adenosine.

Anahtar Kavram

The first-line pharmacologic rate control for multifocal atrial tachycardia (MAT) in patients with severe reactive airway disease or acute COPD exacerbations is a non-dihydropyridine calcium channel blocker.
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Pharmacologic Interventions

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