Page 548 - Cardiac Nursing

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524 PA R T I V / Pathophysiology and Management of Heart Disease
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contractility, sinus node rate, and AV node conduction velocity. 4 has angina. Beneficial effects of calcium channel blockers in
2 -Adrenergic receptors present in vascular and bronchial tissue chronic stable angina are reduction in peripheral vascular resist-
mediate arteriolar dilation and bronchial smooth muscle relaxation. ance, decreased afterload, decreased myocardial oxygen demand,
1 -Selective blockers (i.e., atenolol, metoprolol, and esmolol) are and increased exercise tolerance. 81
considered cardioselective. They are recommended in patients who
have a history of chronic obstructive pulmonary disease because Contraindications/Adverse Reactions. Patients can have
they are less likely to cause bronchospasm. severe hypotension, postural hypotension, or heart block associ-
-Blockers are indicated for the treatment of angina pectoris, ated with calcium channel blockers. Caution should be used with
compensated CHF with a combination medical regimen, ar- patients who have a systolic BP less than 90 mm Hg and/or on di-
81
rhythmias, and hypertension. The primary benefits of -blockers uretic therapy. Peripheral edema is a common side effect.
are due to a decreased cardiac output and myocardial oxygen de- Rapid-release nifedipine must not be used in the absence of -
mand, slower heart rate that increases the diastolic duration and blockers. Diltiazem and verapamil should be avoided in patients 4
filling time, which increases both coronary and collateral blood with pulmonary edema, severe LV dysfunction, or heart block.
4
flow. Oral -blockers are recommended to be initiated promptly Patients who are already on a -blocker should use calcium chan-
in patients with UA/NSTEMI in the absence of contraindication nel blockers cautiously because of synergistic depression of LV
4
within the first 24 hours. Oral -blockers are recommended for function and sinus and AV node conduction. Calcium channel
secondary prevention before hospital discharge. 4 blockers are not indicated for STEMI.
Contraindications/Adverse Reactions. The benefits of Nursing Implications. When calcium channel blockers are
routine early IV use of -blockers in patients with acute MI have initiated, patients should be monitored for hypotension and ar-
been challenged by the randomized Clopidogrel and Metoprolol rhythmias (i.e., bradycardia or heart block). Calcium channel
in Myocardial Infarction Trial/Second Chinese Cardiac Study blockers can be safely used in patients with chronic obstructive
(COMMIT/CCS/2). A total of 45,852 patients were randomized pulmonary disease.
within 24 hours of onset of suspected MI to receive IV metopro-
lol followed by oral metoprolol or placebo for a mean of 15 days. Analgesia
There was no difference in mortality. The use of early -blocker IV Morphine Sulfate
therapy in acute MI reduced the risk of reinfarction and ventric-
ular fibrillation, but increased the risk of cardiogenic shock, Actions/Indications. Morphine sulfate is a potent narcotic
hypotension, and bradycardia seen in the first day after hospital- that produces analgesia and sedation. Morphine sulfate is used for
ization primarily in those patients who were hemodynamically pain associated with ischemia and is the analgesia of choice
2
compromised. 4,82 Early aggressive IV -blocker use is suggested for STEMI. IV doses of morphine starting at 1 to 2 mg are used
with greater caution in patients with STEMI; it should only be for patients whose chest pain/discomfort is not relieved with
4
used in specific patients and should be avoided in patients with NTG or is recurrent despite antiischemic therapies. Morphine
heart failure, hypotension, and/or hemodynamic instability. 4 reduces myocardial oxygen demand because of its venodilation
properties, modest reductions in heart rate (through increased va-
Nursing Implications. Monitoring during IV -blocker gal tone) and systolic BP, and stress reduction via pain relief.
therapy should include frequent checks of heart rate and BP and
continuous ECG monitoring because of the risk of significant Contraindications/Adverse Reactions. Based on retro-
bradycardia and hypotension. Nursing assessment should include spective data concerning the safety of morphine for patients with
auscultation for crackles or wheezes during initiation of -blocker UA/NSTEMI, the ACC/AHA guidelines recommend using cau-
4
therapy because there is a possibility of vasoconstriction and bron- tion when administering morphine to those patients. The major
choconstriction, resulting in pulmonary edema or bronchospasm. adverse reaction to morphine is an exaggeration of its therapeutic
effect, causing hypotension especially in the presence of volume
Calcium Channel Blockers depletion and/or vasodilator therapy. Nausea and vomiting occurs
in 20% of patients. Respiratory depression is the most serious
Actions/Indications. Calcium channel blockers are potent complication with severe hypoventilation requiring intubation.
vasodilators that block the inflow of calcium in smooth muscle
cells. Calcium channel blocker activity results in peripheral arterial Nursing Implications. Patients who develop hypotension
vasodilatation and relaxation of smooth muscle and coronary ar- should be placed supine or in the Trendelenburg position, given
tery dilatation. Commonly used calcium channel blockers include IV saline boluses or infusions, and IV atropine if the hypotension
amlodipine, nifedipine, diltiazem and verapamil. Amlodipine and is accompanied by bradycardia. Antiemetics are used to control
nifedipine have the most potent peripheral arterial dilatory effect. nausea and vomiting. Naloxone (0.4 to 2.0 mg IV) may be ad-
Diltiazem and verapamil, in addition to vasodilatation effects, also ministered for morphine overdose with respiratory or circulatory
decrease sinus node and atrial–ventricular node conduction caus- depressions. Other narcotics may be used for pain relief in pa-
ing decreased heart rates. Negative inotropic effects have been re- tients allergic to morphine.
ported in varying degrees with calcium channel blockers. 81
Calcium channel blockers are indicated for patients with Oral Analgesia
chronic stable angina, variant (Prinzmetal’s) angina, and in pa- There is an increased risk of cardiovascular events among patients
tients with CAD without CHF and an ejection fraction 0.30 or taking cyclooxygenase-2 inhibitors and other nonsteroidal anti-
greater. Calcium channel blockers may be used in patients who are inflammatory drugs. These events include increased mortality, rein-
unresponsive or intolerant to nitrates or -blockers. A calcium farction, hypertension, heart failure, and myocardial rupture with
3
channel blocker may be added to the medical regimen of a patient STEMI. Patients who present with STEMI or UA/NSTEMI
who is adequately treated with nitrates and a -blocker but still should stop these drugs immediately. An alternative pain treatment