The pericardium is a relatively rigid sac that envelops the heart and the roots of the great vessels, working as a point of fixation and physical barrier for the heart [1]. It consists of two layers: a parietal layer, which is fibrous, and a visceral layer, which is a serous membrane. The space between these two layers is known as the intrapericardial space, which contains about 20–25 ml under normal conditions [2]. Pericardial effusion is defined as the abnormal accumulation of fluid in the pericardial cavity, which can develop due to overproduction of pericardial fluid, decreased reabsorption, or an imbalance between the hydrostatic and oncotic pressures of the fluid [3]. There are multiple causes for the development of pericardial effusion such as heart failure, trauma, neoplasms, infections, connective tissue diseases, and metabolic disorders [4].

Pericardial effusion, depending on its volume and time of onset, can lead to increased intrapericardial pressures transmitted to the cardiac cavities, leading to hemodynamic alterations and in severe cases, being associated with shock, a condition known as cardiac tamponade [5, 6]. The diagnosis of pericardial effusion is clinical, supported by echocardiographic findings suggesting alterations in intracardiac filling pressures. In cases of hemodynamic repercussion, shock, or unknown etiology of the effusion, drainage should be performed. The most commonly employed technique is percutaneous pericardiocentesis [7, 8]. Traditionally, the approach to performing this procedure has been based on anatomy or guided by fluoroscopy. However, with the advancement of technology, ultrasound has provided the opportunity to visualize pericardial effusion and adjacent structures, which has led to the development of different techniques and approaches for performing this procedure. Therefore, ultrasound-guided pericardiocentesis should be considered the “gold standard” in contemporary practice [9].

The subxiphoid approach is the most employed technique; however, during this procedure, it is difficult to guide the puncture in real time due to the anatomy and position of the needle. Ultrasound ends up being more of a tool for confirming intrapericardial position rather than real-time guidance [2]. Approaches for pericardiocentesis via anterior, subcostal in-plane [6], and anterior in-plane routes have been described [10]. In this study, we aim to describe an anterior off-plane technique that allows for continuous evaluation of the pleura and the anatomical location of the left internal mammary artery (LIMA) to avoid pneumothorax and inadvertent puncture of the LIMA.