Editing Medical-Surgical Nursing (section)

== Cardiovascular Disorders ==

=== Coronary Artery Disease and Acute Coronary Syndrome ===

Atherosclerotic plaque narrows the coronary arteries. Stable angina occurs with predictable exertion and is relieved by rest and nitroglycerin. Unstable angina occurs at rest, is new, or is worsening in frequency and severity, and it signals impending infarction. Myocardial infarction occurs when a plaque ruptures and a thrombus occludes the vessel, causing myocardial necrosis.

Classic findings include crushing substernal chest pain that may radiate to the jaw, neck, left arm, or back, along with diaphoresis, nausea, dyspnea, and a sense of impending doom. Women, older adults, and people with diabetes often present atypically with fatigue, epigastric discomfort, shortness of breath alone, or new confusion. Silent infarction is common in diabetes because of autonomic neuropathy.

Diagnostics: a twelve-lead electrocardiogram should be obtained within ten minutes of presentation. ST elevation indicates an ST elevation myocardial infarction requiring emergent reperfusion. Troponin I and T are the most specific cardiac markers; they begin to rise about three to four hours after injury, peak within about twelve to twenty-four hours, and remain elevated for up to ten to fourteen days.

Nursing interventions: keep the patient on bed rest with the head of the bed elevated, apply oxygen if the oxygen saturation is below ninety percent or the patient is dyspneic, obtain intravenous access, and give aspirin to chew, nitroglycerin, and analgesia as ordered while monitoring the cardiac rhythm continuously. Nitroglycerin is withheld if the systolic blood pressure is below ninety mm Hg or has fallen substantially from baseline, and it is absolutely contraindicated within twenty-four to forty-eight hours of a phosphodiesterase type 5 inhibitor such as sildenafil or tadalafil because of the risk of profound hypotension.

Nursing application: the most common cause of death in the first hours after infarction is a lethal dysrhythmia, most often ventricular fibrillation. Continuous rhythm monitoring and immediate availability of a defibrillator are not optional. New premature ventricular contractions, ventricular tachycardia, or a new bundle branch block are reported at once.

=== Heart Failure ===

Left-sided failure backs blood into the lungs and produces dyspnea, orthopnea, paroxysmal nocturnal dyspnea, crackles, a persistent dry or frothy pink-tinged cough, an S3 gallop, and fatigue. Right-sided failure backs blood into the systemic venous system and produces jugular venous distention, dependent and sacral edema, hepatomegaly, ascites, and weight gain. Left-sided failure is the most common cause of right-sided failure.

B-type natriuretic peptide rises with ventricular stretch and helps distinguish cardiac dyspnea from pulmonary causes; a level above about one hundred pg/mL supports heart failure, and higher levels correlate with greater severity.

Nursing interventions: elevate the head of the bed to high Fowler position, give oxygen, administer diuretics and monitor the potassium level, restrict sodium and often fluid, weigh daily, and balance activity with rest. Angiotensin converting enzyme inhibitors, angiotensin receptor blockers, beta blockers, and aldosterone antagonists improve survival and are continued even when the patient feels well.

Nursing application: teach the patient to weigh every morning after voiding and before breakfast, and to call the provider for a gain of two to three pounds in one day or five pounds in one week. That single instruction prevents more readmissions than almost any other teaching point.

Acute pulmonary edema is a medical emergency: severe dyspnea, anxiety, frothy pink sputum, crackles throughout the lung fields, and hypoxemia. Sit the patient upright with legs dependent, give high-flow oxygen, and prepare for intravenous furosemide, nitrates, and possible noninvasive positive pressure ventilation.

=== Hypertension ===

Hypertension is usually asymptomatic until organ damage occurs, which is why it is called the silent killer. Complications include stroke, myocardial infarction, heart failure, kidney failure, and retinopathy.

Nursing application: teach the DASH eating pattern, sodium restriction, weight loss, aerobic activity, limited alcohol, and smoking cessation. Warn about orthostatic hypotension with antihypertensives, especially alpha blockers and vasodilators, and teach the patient to change positions slowly. Emphasize that feeling fine is not a reason to stop the medication; nonadherence is the leading cause of treatment failure.

Hypertensive crisis with a systolic pressure above about one hundred eighty mm Hg accompanied by headache, blurred vision, chest pain, or neurologic change requires emergent evaluation and controlled, gradual lowering of pressure.

=== Dysrhythmias ===

Atrial fibrillation produces an irregularly irregular rhythm with no discernible P waves and a pulse deficit between apical and radial rates. Blood pools in the fibrillating atria, so the major risk is thromboembolic stroke; anticoagulation is central to management. Rate control and, in selected patients, rhythm control or ablation follow.

Ventricular tachycardia with a pulse in an unstable patient calls for synchronized cardioversion; without a pulse it is treated as cardiac arrest with defibrillation and cardiopulmonary resuscitation. Ventricular fibrillation is always pulseless and requires immediate defibrillation. Asystole and pulseless electrical activity are not shockable; they are treated with compressions, epinephrine, and correction of reversible causes.

Symptomatic bradycardia is treated with atropine, and if that fails, with transcutaneous pacing.

=== Peripheral Vascular Disease ===

Peripheral arterial disease produces intermittent claudication, pain relieved by dangling the legs, diminished or absent pulses, cool and shiny hairless skin, thick nails, pallor on elevation, dependent rubor, and painful ulcers on the toes or lateral malleolus. Venous insufficiency produces aching heaviness relieved by elevation, warm skin, brown hemosiderin staining, edema, and shallow weeping ulcers near the medial malleolus.

Nursing application: elevate legs for venous disease and avoid elevation for arterial disease. Compression stockings help venous disease and are dangerous in significant arterial disease. Never apply heat directly to an ischemic or neuropathic extremity.

Deep vein thrombosis presents with unilateral calf or thigh swelling, warmth, redness, and tenderness. Do not massage the extremity. Anticoagulation is the treatment; the feared complication is pulmonary embolism.

=== Selected Cardiac Medications ===

Digoxin increases contractility and slows conduction. The therapeutic serum level is roughly 0.5 to 2.0 ng/mL, with lower targets used in heart failure. Toxicity presents with anorexia, nausea, vomiting, visual disturbances such as halos or yellow-green vision, confusion, and bradycardia or new dysrhythmias. Hold the dose and notify the provider if the apical pulse is below sixty beats per minute in an adult, counted for a full minute. Hypokalemia potentiates toxicity.

Beta blockers reduce heart rate, contractility, and blood pressure. Hold and reassess for bradycardia or hypotension per parameters, do not stop abruptly because of rebound ischemia and hypertension, and be aware they can mask the tachycardia and tremor of hypoglycemia.

Angiotensin converting enzyme inhibitors cause a dry persistent cough, hyperkalemia, and rarely angioedema, which is an airway emergency. Monitor potassium and kidney function.

Warfarin is monitored by the international normalized ratio, with a usual therapeutic range of 2.0 to 3.0 for most indications; the antidote is vitamin K. Heparin is monitored by activated partial thromboplastin time at about 1.5 to 2.5 times control; the antidote is protamine sulfate. A platelet count that falls sharply after several days of heparin suggests heparin-induced thrombocytopenia, and all heparin must be stopped.