Non-Dihydropyridine Calcium Channel Blockers

Non-Dihydropyridine Calcium Channel Blockers (Non-DHP CCBs) block L-type calcium channels in both cardiac myocytes and vascular smooth muscle.

Unlike Dihydropyridine Calcium Channel Blockers, Non-DHP agents significantly affect cardiac conduction and contractility.

They are primarily used for:

• Rate control in arrhythmias • Angina • Hypertension (select cases)

Non-DHP CCBs:

• Block L-type calcium channels in:

1. SA node
2. AV node
3. Cardiac myocytes
4. Vascular smooth muscle

Net Effects:

• ↓ Heart rate • ↓ AV nodal conduction • ↓ Myocardial contractility • Mild ↓ SVR

Primary clinical impact: ↓ Cardiac Output

• Verapamil • Diltiazem

Verapamil: More cardiac-selective

Diltiazem: Balanced cardiac + vascular effects

• Rate control via AV nodal slowing

→ Dysrhythmias Module

• AV node suppression

• ↓ Heart rate • ↓ Contractility • ↓ Oxygen demand

→ Anti-Anginal Module

• Alternative therapy • Not first-line compared to DHP CCBs

→ Hypertension Module

Avoid in:

• HFrEF (reduced ejection fraction) • Advanced AV block (without pacemaker) • Severe bradycardia

See: → Heart Failure Module

Non-DHP CCBs can worsen systolic heart failure due to negative inotropic effects.

• Bradycardia • AV block • Hypotension • Constipation (verapamil) • Peripheral edema (less than DHPs)

Use caution with:

• Beta-Blockers (risk of severe bradycardia or heart block)

• Digoxin (verapamil increases levels)

DHP CCBs: • Strong arteriolar vasodilators • Minimal conduction effects • First-line for hypertension

Non-DHP CCBs: • AV node suppression • Rate control agents • Avoid in HFrEF

✔ Best for rate control in atrial fibrillation ✔ Verapamil more cardiac-selective ✔ Avoid in systolic heart failure ✔ Use caution with beta-blockers ✔ Not preferred first-line for hypertension

Related:

→ Dihydropyridine Calcium Channel Blockers → Hypertension Module → Dysrhythmias Module → Heart Failure Module → Return to Cardiovascular Modules