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Cardiac arrhythmias are associated with significant morbidity, mortality and poor quality of life. Cardiovascular magnetic resonance (CMR) imaging, with its unsurpassed capability of non-invasive tissue characterisation, high accuracy, and reproducibility of measurements, plays an integral role in determining the underlying aetiology of cardiac arrhytmias. CMR can reliably diagnose previous myocardial infarction, non-ischemic cardiomyopathy, characterise congenital heart disease and valvular pathologies, and also detect the underlying substrate concealed on conventional investigations in a significant proportion of patients with arrhythmias. Determining the underlying substrate of arrhythmia is of paramount importance for treatment planning and prognosis. However, CMR imaging in patients with irregular heart rates can be problematic. Understanding the different ways to overcome the limitations of CMR in arrhythmia is essential for providing high-quality imaging, comprehensive information, and definitive answers in this diverse group of patients.

Summary: Pre-conditioning is an exciting physiological phenomenon that, despite great efforts, has so far resisted translation to mainstream clinical medicine. Many potential triggers (e.g., ischemia of the organ in question or a remote organ, many different drugs) have been investigated, but recent work has implicated activation of mitochondrial aldehyde dehydrogenase (ALDH2) as central to the process. A genetic polymorphism, known as ALDH2*2, is common worldwide (present in up to 40% of Han Chinese people) and produces a functionally different enzyme. The authors used a variety of protocols in the human ischemic forearm model, in participants with both enzyme types, to assess cytoprotection with low-dose sodium nitrite and attempt to further elucidate the role of ALDH2. Key Words: cytoprotection, endothelium, nitric oxide, nitrite, reperfusion injury