19.3 Implement Nutritional Strategies to Impact Musculoskeletal and Integumentary Wellness

Calcium channel blockers are crucial medications for managing heart rhythm disorders. They work by blocking calcium entry into heart cells, slowing conduction and reducing contractility. This helps control rapid heart rates in conditions like atrial fibrillation and supraventricular tachycardia.

These drugs also dilate coronary arteries, improving blood flow to the heart. While effective for treating dysrhythmias, they can cause side effects like low blood pressure and slow heart rate. Proper monitoring and patient education are essential for safe and effective use of calcium channel blockers.

Calcium Channel Blockers for Dysrhythmias

Mechanisms of calcium channel blockers

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• Block L-type calcium channels in cardiac muscle cells
  • Reduce calcium influx during depolarization, which is necessary for muscle contraction
  • Decrease intracellular calcium concentration, leading to reduced contractility (inotropy)
  • Disrupt excitation-contraction coupling, affecting the heart's ability to contract
• Slow conduction through the AV node
  • Prolong AV nodal refractory period, preventing rapid impulse transmission
  • Decrease ventricular rate in atrial fibrillation and flutter (SVT)
• Dilate coronary arteries
  • Improve coronary blood flow, increasing oxygen supply to the heart muscle (myocardium)
  • Reduce myocardial oxygen demand by decreasing cardiac workload
• Decrease contractility and oxygen consumption
  • Reduce afterload (resistance against which the heart must pump) and preload (volume of blood in the ventricles at the end of diastole)
  • Beneficial in hypertrophic cardiomyopathy by reducing outflow tract obstruction and improving diastolic function

Effects of calcium channel blockers

• Therapeutic uses
  • Supraventricular tachycardias (SVT)
    • Atrial fibrillation and flutter, characterized by rapid and irregular atrial contractions
    • AV nodal reentrant tachycardia (AVNRT), caused by a reentry circuit within the AV node
  • Angina pectoris, chest pain caused by insufficient blood flow to the heart muscle
  • Hypertrophic cardiomyopathy, a genetic disorder causing thickening of the heart muscle
• Effects
  • Slow ventricular rate in SVT, improving cardiac function and reducing symptoms
  • Reduce myocardial oxygen demand, alleviating angina symptoms
  • Improve coronary blood flow, enhancing oxygen supply to the heart muscle
  • Decrease outflow tract obstruction in hypertrophic cardiomyopathy, improving cardiac output
  • Exert a negative inotropic effect, reducing the force of heart contractions
• Potential side effects
  • Hypotension (low blood pressure) due to vasodilation and reduced contractility
  • Bradycardia (slow heart rate) and heart block (impaired conduction) due to AV node suppression
  • Peripheral edema (swelling) due to vasodilation and fluid retention
  • Constipation due to smooth muscle relaxation in the gastrointestinal tract
  • Dizziness and headache due to vasodilation and hypotension

Cardiac electrophysiology and calcium channel blockers

• Voltage-gated ion channels play a crucial role in generating and propagating cardiac action potentials
• Calcium channel blockers primarily affect the plateau phase of the cardiac action potential
• These medications influence both chronotropic (heart rate) and inotropic (contractility) effects
• Calcium channel blockers also act on vascular smooth muscle, leading to vasodilation and reduced peripheral resistance

Nursing considerations for administration

• Assess baseline vital signs and cardiac rhythm to establish a reference point
• Monitor blood pressure and heart rate closely
  • Report significant changes to the healthcare provider, as they may indicate the need for dose adjustment or intervention
• Administer medication as prescribed
  • Use caution in patients with heart failure or conduction disorders, as they may be more sensitive to the effects of calcium channel blockers
• Observe for signs of heart block or bradycardia
  • Prepare for temporary pacing if necessary, to maintain adequate heart rate and cardiac output
• Educate patients on potential side effects and when to seek medical attention
• Encourage medication adherence and regular follow-up appointments to ensure optimal treatment outcomes

Patient education for calcium channel blockers

• Explain the purpose and mechanism of action of the prescribed calcium channel blocker
  • Use simple terms and analogies to help the patient understand how the medication works (slowing down the heart's electrical system)
• Instruct the patient on proper dosage, timing, and administration of the medication
  • Emphasize the importance of taking the medication as directed to maintain consistent therapeutic levels
• Discuss common side effects and how to manage them
  • Advise when to contact the healthcare provider for concerning symptoms (severe dizziness, fainting, or persistent edema)
• Encourage lifestyle modifications to support heart health
  • Regular exercise (walking), stress management (meditation), and a heart-healthy diet (low in saturated fat and sodium)
• Stress the importance of regular follow-up appointments and monitoring
  • Discuss the need for periodic blood tests and ECGs to assess the effectiveness and safety of the medication
• Provide written materials and resources for additional information and support
  • Include contact information for the healthcare team and emergency services to ensure prompt assistance if needed