Chapter 35: Critical Care of Patients With Acute Coronary Syndromes

The underlying pathophysiology involves rupture of atherosclerotic plaque within a coronary artery, triggering platelet aggregation, thrombus formation, and subsequent vasoconstriction that compromises blood flow to the myocardium. The chapter distinguishes between non-ST-elevation myocardial infarction, characterized by partial coronary occlusion with ST-segment depression or T-wave inversion on electrocardiography, and ST-elevation myocardial infarction, representing complete coronary artery occlusion with full-thickness myocardial necrosis evidenced by ST-segment elevation. Time-sensitive interventions are paramount, requiring a 12-lead electrocardiogram within ten minutes of patient arrival and achievement of myocardial reperfusion within four to six hours to minimize tissue damage. Diagnostic confirmation relies on serial electrocardiographic changes and elevation of cardiac troponin biomarkers. Acute pharmacological management prioritizes reducing myocardial oxygen consumption and restoring coronary perfusion through antiplatelet agents, nitrates, and anticoagulation, with careful attention to medication contraindications such as nitrate use in patients taking phosphodiesterase inhibitors. Definitive reperfusion strategies include percutaneous coronary intervention with stent placement or fibrinolytic therapy, while severe multivessel disease may necessitate coronary artery bypass grafting. Dual antiplatelet therapy reduces thrombotic complications but requires vigilant bleeding surveillance. Post-infarction complications including dysrhythmias, ventricular remodeling, and cardiogenic shock require specialized hemodynamic monitoring and supportive interventions. Post-operative nursing management of bypass patients emphasizes detection of hemorrhage, hypothermia, and cardiac tamponade, identified through Beck triad findings. Long-term recovery incorporates risk factor modification through lifestyle changes and participation in structured cardiac rehabilitation programs to optimize functional capacity and prevent recurrent events.