• Calcium Channel Blockers (CCB)
• ECG and Non-dihydropyridine CCBs (Intoxication)

Calcium Channel Blockers (CCB)

• Inhibit the entry of calcium into the cells of blood vessels and the heart, resulting in:
• Vasodilation
• Inhibition SA node and AV node
• Reduced contractility of the myocardium
• Used to treat high blood pressure
  
  
• CCBs are classified based on chemical structure into:
• Dihydropyridine CCBs
• Mainly act on blood vessels
• resulting in vasodilation
• Minimal ECG changes occur in overdose
• Examples: Amlodipine, Nitrendipine, Felodipine, Lacidipine...
• Non-dihydropyridine CCBs
• Mainly act on cardiomyocytes, resulting in:
• Negative inotropy (reduced contractility)
• Negative chronotropy (reduced rate of impulses)
• Negative dromotropy (reduced conduction of impulses)
• ECG changes occur in overdose
• There are only 2: Verapamil, Diltiazem

Non-dihydropyridine CCBs (Intoxication)

• First-degree AV block
• PQ interval > 0.2s
• is the first sign of intoxication
• Sinus bradycardia (45/min)
• The patient was overdosed with Verapamil
• Beta-blockers can produce the same ECG pattern

Non-dihydropyridine CCBs (Intoxication)

• AV block III degree
• Frequency of P waves: 90/min.
• Frequency of QRS: 30/min.
• AV dissociation
• P waves and QRS are independent because the atria and ventricles are electrically isolated
• QRS have the shape of right bundle branch block, it could be:
• Junctional rhythm with RBBB
• Ventricular rhythm with ectopic focus in the left ventricle
• The patient was overdosed with Verapamil
• Beta-blockers can produce the same ECG pattern