Atrial fibrillation is initiated by triggers in combination with underlying atrial substrate. Horizons in World Cardiovascular Research. Volume 17 discusses how innovations in cardiac magnetic resonance imaging techniques, especially late gadolinium enhancement imaging, have advanced our ability to better understand and accurately identify fibrosis in the atrial myocardium of atrial fibrillation patients. According to the nephron number hypothesis, individuals born with kidneys with fewer nephrons would be at increased risk for hypertension and renal disease later in life. Evidence supporting a role for preterm birth itself as a programming risk factor come from observations demonstrating that the degree of prematurity impacts the severity of hypertension or renal dysfunction observed later in life, indicating a dose-response effect of preterm birth. As such, the authors review this effect in the context of consequences for the mother after pregnancy as well as individuals born during premature labor. This compilation goes on to discuss venous thromboembolism, a spectrum of disease that includes both deep venous thrombosis and pulmonary embolism. Venous thromboembolism affects 950,000 patients every year and is associated with significant morbidity and mortality. Superior mesenteric artery syndrome is a rare clinical entity resulting in partial or complete duodenal obstruction due to compression of the third part of the duodenum. Symptoms will vary depending on the severity, but can be very debilitating. The authors discuss the diagnosis of this rare condition, as well as treatment options. Next, the surgical anatomy of the superior mesenteric artery is schematized through a subdivision in three segments, each with a different method for surgical dissection, for a better understanding of its surgical anatomy. The final chapter focuses on the current development of zebrafish models for the screening for cardiotoxic and cardioprotective agents. The administration of endocrine disruptors, cigarette smoke, acrylamide, phthalates and phosphate, heavy metals, inoculation infectious agent, alcohol, surgery and laser light radiations are the major cause of cardiotoxicity in zebrafish.