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The higher incidence of cardiovascular events in the morning is accompanied by an increased vascular tone. However, there are few published studies designed to evaluate the diurnal variation of vascular and endothelial parameters in healthy subjects. In the present investigation, we evaluated the diurnal variation in brachial artery diameter (BAD), flow-mediated dilation (FMD) and endothelium-independent dilation (NFMD) in a homogeneous sample of healthy non-smoker young men. Fifty subjects aged 20.8 ± 0.3 years (range: 18 to 25 years) were investigated by brachial artery ultrasound. Exclusion criteria were female gender and evidence of clinically significant health problems, including obesity. Volunteers were asked to rest and avoid fat meals as well as alcoholic beverages 48 h before and until completion of the evaluations. BAD, FMD and NFMD were measured at 7 am, 5 pm, and 10 pm and tested by repeated measures ANOVA. BAD was smaller at 7 am (mean ± SEM, 3.8 ± 0.1 mm) in comparison with 5 pm (3.9 ± 0.1) and 10 pm (4.0 ± 0.1 mm; P < 0.001). FMD values did not change significantly during the day, while NFMD increased more at 7 am (18.5 ± 1.1%), when compared to 15.5 ± 0.9% at 10 pm and 15.5 ± 0.9% at 5 pm (P = 0.04). The physiological state of vasoconstriction after awakening, with preserved capability to dilate in the morning, should be considered to be part of the healthy cardiovascular adaptation before considering later life risk factors and endothelial dysfunction.

Recent advances in cancer treatment and research have greatly improved survival rates for patients with cancer. However, many of these cancer survivors are developing cardiac disease-most commonly heart failure as a result of this treatment. Certain chemotherapeutic agents, including anthracyclines and trastuzumab, have been linked to cardiotoxicity-induced cardiomyopathy in cancer patients. It has been reported as early as during infusion and as late as several years following treatment. Radiation therapy, particularly to the left breast, has also been linked to cardiac disease. The responsibility of cardiac monitoring has traditionally fallen on oncologists using assessment of LVEF through multigated acquisition (MUGA) scans or echocardiograms. The "formal" definition of cardiotoxicity, as a 5 to 10% decrease in LVEF from its baseline, even though not validated, is currently used by clinicians to alter treatment, but it has been recently challenged, as a possible irreversible late stage of a myocardial insult. Furthermore, it falls into the interobserver variability range of echocardiography. The growing field of medicine called cardio-oncology is based on emerging research that has shown that more advanced imaging modalities can help detect cardiotoxicity early, allowing the patient to receive treatment and avoid developing heart failure from cancer treatment. While traditional imaging still has its place in cardiac monitoring, cardiac magnetic resonance imaging is the most accurate and detailed imaging modality available to assess cardiotoxicity. Our own pilot cardiac MRI study suggests that a normal left ventricular remodeling to chemotherapy, when patients have not developed heart failure symptoms, could occur over time. Perhaps, knowing a baseline normal response could help us to define a more accurate definition of cardiotoxicity by CMR. Here, we discuss various imaging modalities and emerging techniques that can assist in detecting early signs of cardiotoxicity and thus reduce the incidence of cardiac disease in cancer survivors.