Tachyarrhythmias affect 1-5% of neonates and result from an abnormal conduction of the depolarization wave, which in 80% of cases manifests as paroxysmal supraventricular tachycardia (PSVT). These arrhythmias are generally well tolerated but sometimes may lead to acute heart failure. There is currently no universally rec-ognised therapeutic protocol, whereby treatments are based on studies with few samples. Through the investi-gation of an atypical case of tachyarrhythmia in a prem-ature newborn an attempt is made to develop a pathoge-netic model of the observed clinical events and through the analysis of the interventions carried out actions of good clinical practice are proposed so as to improve the outcome of neonatal tachyarrhythmias. In the case de-scribed, the high number of atrial extrasystoles together with the presence of an accessory pathway favoured the coexistence of supraventricular tachycardia and atrial flutter. The latter, when present in foetal or neonatal age, usually does not recur after restoration of sinus rhythm. The patient’s arrhythmic episode is only the sec-ond case described in the literature of relapsing flutter after effective cardioversion in a preterm newborn. The patient also presented resistant hypotension that required therapy personalised to the peculiarities of the case as there are currently no protocols dedicated to preterm newborns with hypotension during recurrent TPSV de-spite antiarrhythmic prophylaxis. Given the lack of unique guidelines, the knowledge of the pathophysiology of neonatal tachyarrhythmias is essential to optimise the treatment. The described case provides new clinical ele-ments of comparison for the understanding of neonatal arrhythmias and proposes interventions for the resolu-tion of complex arrhythmias in a critical way.