====== 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 [[cardio:ccb:dhp|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)

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===== Mechanism of Action =====

Non-DHP CCBs:

• Block L-type calcium channels in:
  - SA node
  - AV node
  - Cardiac myocytes
  - Vascular smooth muscle

Net Effects:

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

Primary clinical impact:
↓ Cardiac Output

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===== Available Agents =====

• [[cardio:ccb:verapamil|Verapamil]]
• [[cardio:ccb:diltiazem|Diltiazem]]

Verapamil:
More cardiac-selective

Diltiazem:
Balanced cardiac + vascular effects

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===== Indications =====

==== Atrial Fibrillation / Atrial Flutter ====

• Rate control via AV nodal slowing

→ [[cardio:arrhythmias:start|Dysrhythmias Module]]

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==== Supraventricular Tachycardia ====

• AV node suppression

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==== Stable Angina ====

• ↓ Heart rate
• ↓ Contractility
• ↓ Oxygen demand

→ [[cardio:angina:start|Anti-Anginal Module]]

----

==== Hypertension ====

• Alternative therapy
• Not first-line compared to [[cardio:ccb:dhp|DHP CCBs]]

→ [[cardio:hypertension:start|Hypertension Module]]

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===== Contraindications =====

Avoid in:

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

See:
→ [[cardio:heart_failure:start|Heart Failure Module]]

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

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===== Adverse Effects =====

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

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===== Drug Interactions =====

Use caution with:

• [[cardio:beta_blockers:start|Beta-Blockers]]  
  (risk of severe bradycardia or heart block)

• Digoxin (verapamil increases levels)

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===== DHP vs Non-DHP Summary =====

[[cardio:ccb:dhp|DHP CCBs]]:
• Strong arteriolar vasodilators  
• Minimal conduction effects  
• First-line for hypertension  

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

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===== Clinical Pearls =====

✔ 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  

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Related:

→ [[cardio:ccb:dhp|Dihydropyridine Calcium Channel Blockers]]
→ [[cardio:hypertension:start|Hypertension Module]]
→ [[cardio:arrhythmias:start|Dysrhythmias Module]]
→ [[cardio:heart_failure:start|Heart Failure Module]]
→ [[cardio:intro:start|Return to Cardiovascular Modules]]