Ischemic Heart Disease (IHD) (Myocardial Infarction, Angina Pectoris)


Etiology and Pathophysiology

■ Fatty deposits in intima of coronary arteries triggers inflammatory process → plaques (atheromas) → further obstruction of blood flow → chest pain secondary to myocardial ischemia (angina pectoris)

■ Rupture of atheroma → thrombus → severe ischemia and myocardial cell death (myocardial infarction [MI])

■ Other causes of MIs include ↓myocardial O2 supply (2 degrees vasospasm,
hemorrhage) or ↑O2 demand (2 degrees cocaine, hyperthyroidism)

Risk Factors

■ Aging, family history, race (↑African Americans), gender (males more than
premenopausal females)

■ HTN, diabetes mellitus, metabolic syndrome (insulin resistance,
abdominal obesity, abnormal lipid profile

■ Modifiable risk factors: smoking, obesity, sedentary lifestyle

■ ↑Cholesterol, ↑triglycerides, ↑LDL, ↓HDL, ↑C-reactive protein (CRP)

Signs and Symptoms

Angina

■ Chest pain/pressure may be substernal and/or radiate to neck, jaw, left
arm

■ Precipitated by exertion (↑O2 demand), cold exposure (vasoconstriction),
stress (sympathetic nervous system activity → ↑O2 demand), heavy meal
(blood diverted to GI tract → ↓blood to heart)

■ Pain subsides with rest and/or nitroglycerin

Myocardial Infarction

■ May have sudden chest pain (see Angina) unrelieved by rest/nitroglycerin

■ SOB; restlessness; dysrhythmias

■ Pulse deficit if atrial fibrillation

■ Cool, pale, clammy skin; diaphoresis; N&V

■ Early S&S in women: Overwhelming fatigue, dizziness, indigestion,
anxiety, trouble sleeping

Diagnosis

■ ECG: ↑ST segment, inverted T wave, presence of Q wave

■ Echocardiogram identifies ↓ventricular wall motion and ↓ejection fraction

■ ↑Myoglobin (1st to rise, but returns to normal in 12hr)

■ ↑Creatine kinase (CK)

■ Isoenzyme specific to heart muscle: ↑CK-MB, which ↑4-6hr after MI,
↑cardiac troponin T (cTnT) and I (cTnl), which remains ↑for 3-12hr after MI

Treatment (↓Cardiac Demands and ↑ O2 to Cardiac Muscle)

Angina

■ ↓Modifiable risk factors, percutaneous coronary interventional procedures
(PCTA, atherectomy, stent); CABG

■ Meds: nitroglycerin, beta-blockers, calcium channel blockers, antiplatelets,
anticoagulants, antilipidemics

■ O2 prn; cardiac rehab to ↑exercise tolerance and quality of life

Myocardial Infarction

■ Provide O2, morphine to ↓pain, ACE inhibitors to ↓cardiac workload

■ IV thrombolytic within 3hr of start of MI to dissolve clot and ↓damage

■ Emergency PCI

Nursing Management

Angina

■ Monitor S&S, balance activity/rest, give sublingual nitroglycerin and O2
prn

■ Teach about meds and to ↓modifiable risk factors

Myocardial Infarction

■ Monitor S&S, ↑HOB, ↓anxiety

■ Maintain IV access (avoid fluid overload)

■ Identify complications (heart failure, pulmonary edema, dysrhythmias, cardiogenic shock)

■ Give prescribed thrombolytic, analgesics, beta-blockers, ACE inhibitors, anticoagulants, stool softeners

■ Maintain BR until stable

Percutaneous transluminal coronary angioplasty (PCTA)
■ Monitor for bleeding (restlessness, back pain due to retroperitoneal bleed, ↑P, ↓BP, ↓Hgb/Hct)
■ Apply pressure to insertion site, keep hip extended
■ Assess pulses of distal extremity

Postoperative coronary artery bypass graft (CABG)
■ Monitor hemodynamic status, which may be ↑ (due to heart failure or fluid overload)
or ↓ (due to fluid deficit or bleeding)
■ Assess pulses below vein harvest site
■ Monitor ECG for dysrhythmias
■ Assess urine output (if <30mL/hr, may indicate ↓renal perfusion)
■ Monitor electrolytes and coagulation profile
■ Maintain chest tube drainage and ventilator as needed, then encourage
incentive spirometer, splinting, coughing, and deep breathing
■ Provide for alternate communication while intubated
■ Provide pain control
■ Refer to cardiac rehab and Mended Hearts Club
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