(thorazine), and thiethylperazine (Torecan); and butyrophenones such as droperidol and haloperidol Since more effective antiemetics, such as serotonin-receptor antagonists, have become available, the use of these drugs has decreased along with the incidence of this side effect If an extrapyramidal reaction is suspected, management should include diphenhydramine mg/kg IV (maximum dose 50 mg) If symptoms are refractory to diphenhydramine, benztropine (Cogentin) should be given at a dosage of 0.02 mg/kg IV (maximum mg) CARDIOVASCULAR COMPLICATIONS Cancer treatment can affect cardiac function in patients during treatment and long after completion of therapy Anthracycline-induced cardiomyopathy is the most common cause of cardiac damage in pediatric oncology patients although only a small percentage are affected Anthracycline chemotherapy, most commonly with doxorubicin (Adriamycin) and daunorubicin (Daunomycin), is widely used in the treatment of leukemia, lymphoma, sarcoma, and embryonal tumors such as neuroblastoma and Wilms tumor These drugs injure and potentially kill individual cardiomyocytes and can cause acute cardiomyopathy during and up to year after the end of treatment Late cardiomyopathy may develop or more years after completion of therapy Typical findings on echocardiogram include decreased shortening fraction/ejection fraction and/or increased afterload Specific risk factors include high total dose (greater than 300 mg/m2), high-dose rate, very young age at treatment, and trisomy 21 Most regimens today are designed to minimize the risk of cardiomyopathy by limiting total dose and dose rate and/or giving dexrazoxane, a cardioprotectant Patients exposed to substantial doses of anthracycline are screened with echocardiograms to look for early cardiac dysfunction Early-onset cardiomyopathy usually presents as acute cardiac failure or cardiac dysfunction out of proportion to a stressor such as sepsis Late-onset cardiomyopathy is generally a slowly progressive process that may be detected on screening Both forms may be associated with arrhythmias The initial management of this problem follows the standard regimen for cardiac failure (see Chapter 86 Cardiac Emergencies ) Radiation to the heart can cause long-term injury to the endothelial surfaces leading to early-onset atherosclerotic vessel and/or valve disease The heart is exposed in mantle radiation for Hodgkin disease and total body irradiation as part of a transplant preparative regimen Hypertension may occur in pediatric oncology patients due to steroid exposure, salt overload, and renal injury from treatment Most hypertension is not an emergency and is better addressed by the treating oncologist as part of long-term management Hypertensive emergencies (see Chapter 37 Hypertension ) are rare in pediatric oncology patients