Chemotherapy — Cardiotoxic Agents

Doxorubicin (Adriamycin) is an anthracycline antibiotic that intercalates DNA and generates free radicals, destroying rapidly dividing cells. The critical nursing concern is cumulative, dose-dependent cardiotoxicity. Free radicals damage cardiac myocytes, which cannot regenerate. Cardiotoxicity presents in two forms: acute (during or shortly after infusion — transient arrhythmias, ECG changes) and chronic (weeks to years later — irreversible cardiomyopathy progressing to heart failure). The lifetime cumulative dose limit is 550 mg/m²; exceeding it dramatically increases heart failure risk. Before therapy begins, a baseline ejection fraction (EF) is obtained via echocardiogram or MUGA scan, with serial monitoring throughout treatment. An EF dropping below 50% or declining ≥10% from baseline warrants holding the drug and notifying the provider. Dexrazoxane is a cardioprotective agent sometimes given before doxorubicin to chelate iron and reduce free radical formation in cardiac tissue. The nurse monitors for signs of heart failure at every visit: weight gain, peripheral edema, dyspnea, jugular vein distention, crackles, and decreasing exercise tolerance. Patient teaching includes daily weights, reporting new shortness of breath immediately, and understanding that cardiac monitoring will continue even after chemotherapy ends because late-onset cardiomyopathy can appear months to years later.