Perverse T waves and chronic beta-blocker treatment

Cardiotoxicity of Antineoplastic Therapies and Applications of Induced Pluripotent Stem Cell-Derived Cardiomyocytes

The therapeutic landscape for the treatment of cancer has evolved significantly in recent decades, aided by the development of effective oncology drugs. However, many cancer drugs are often poorly tolerated by the body and in particular the cardiovascular system, causing adverse and sometimes fatal side effects that negate the chemotherapeutic benefits. The prevalence and severity of chemotherapy-induced cardiotoxicity warrants a deeper investigation of the mechanisms and implicating factors in this phenomenon, and a consolidation of scientific efforts to develop mitigating strategies. Aiding these efforts is the emergence of induced pluripotent stem cells (iPSCs) in recent years, which has allowed for the generation of iPSC-derived cardiomyocytes (iPSC-CMs): a human-based, patient-derived, and genetically variable platform that can be applied to the study of chemotherapy-induced cardiotoxicity and beyond. After surveying chemotherapy-induced cardiotoxicity and the associated chemotherapeutic agents, we discuss the use of iPSC-CMs in cardiotoxicity modeling, drug screening, and other potential applications. Improvements to the iPSC-CM platform, such as the development of more adult-like cardiomyocytes and ongoing advances in biotechnology, will only enhance the utility of iPSC-CMs in both basic science and clinical applications.

Functional and myocarditis-induced T-wave abnormalities. Effect of orthostasis, beta-blockade, and epinephrine

Negative T waves in the ECG during an acute infection may be due purely to functional variations, making the diagnosis of acute myocarditis difficult. The effects of orthostasis, beta-blockade, and intravenous epinephrine infusion (0.07-0.21 micrograms/kg/min) on T waves and the Q-T interval was studied in 28 young men with acute myocarditis, in 29 persons with functional T-wave abnormalities, and in 30 healthy subjects. Myocarditis-induced negative T waves were never normalized by beta-blockade. Functional T-wave inversions were normalized by beta-blockade in 22 subjects (76 percent). Orthostasis always augmented the T-wave abnormalities that were normalized by beta-blockade. Functional T-wave abnormalities responding to beta-blockade were augmented by epinephrine in 17 subjects (77 percent); but those unresponsive to beta-blockade were normalized in six of seven subjects. The Q-Tc interval was significantly (p less than 0.01) lengthened in subjects with myocarditis (410 +/- 36 ms) compared with controls (384 +/- 27 ms). The beta-blockade test is useful in differentiating between functional T-wave inversions and acute myocarditis. However, functional T-wave abnormalities are not constantly abolished by beta-blockade but may then be normalized by epinephrine. A clearly prolonged Q-Tc interval speaks for a diagnosis of myocarditis.