Anatomical descriptions should refer to the heart as it lies within the body of a person standing in the anatomical position. This attitudinal approach provides a common spatial language for anatomy, imaging, fluoroscopy, electroanatomical mapping, and catheter ablation. Traditional electrophysiological terminology often described the heart as though it were removed from the thorax and placed on its apex in the Valentine position. As a result, several regions labelled anterior, posterior, or septal do not occupy those positions in the body.[1,2]

The Heart Within the Thorax

The long axis of the cardiac mass is oblique. It extends from a broad posterior and superior base toward an apex directed anteriorly, inferiorly, and to the left. The right ventricle lies immediately behind the sternum and is anterior to the left ventricle. The right atrium is anterior and to the right of the left atrium. The left atrium is the most posterior chamber and lies directly anterior to the oesophagus. The atrial septal plane is oblique rather than sagittal, and the mitral and tricuspid valvar orifices lie at different levels.[2]

Anatomical Axes

The terms anterior and posterior describe relationships toward the sternum and vertebral column. Superior and inferior refer to the cranial and diaphragmatic directions, and right and left refer to the patient’s own sides. These axes remain constant irrespective of the observer, the imaging plane, or the position in which an isolated specimen is displayed.[1]

The Limitation of the Valentine Position

The traditional Valentine display places the heart on its apex and presents the chambers as though the cardiac mass were vertically oriented. This convention is useful for showing an isolated specimen, but it rotates the heart away from its true thoracic position. Terms derived from that view can therefore misidentify inferior structures as posterior and superior structures as anterior. The discrepancy becomes clinically important when anatomical names are used to guide catheter position or energy delivery.[1]

Cross Sectional Imaging and Spatial Orientation

Axial computed tomographic and magnetic resonance images provide an unambiguous reference for anterior, posterior, right, and left. Reformatted right anterior oblique and left anterior oblique planes reproduce the projections used during fluoroscopy while retaining the true spatial relationships of the chambers and junctions. Cross-sectional datasets therefore provide the bridge between gross anatomy and the two-dimensional fluoroscopic image.[1]

Right Anterior Oblique Projection

The right anterior oblique projection separates structures primarily along the anterior-posterior and superior-inferior axes. It helps define the anterior position of the right ventricle, the posterior location of the left atrium, the level of the atrioventricular junctions, and the course of catheters within the right-sided chambers and coronary sinus. A single projection cannot establish the complete three-dimensional location of a catheter, so it should be interpreted together with an orthogonal or oblique view.[1,2]

Left Anterior Oblique Projection

The left anterior oblique projection displays the right and left atrioventricular junctions more nearly en face. It is useful for distinguishing right-sided from left-sided locations and for identifying superior, inferior, anterior, and posterior sectors around the valvar orifices. It also clarifies why many sites formerly called septal are more accurately described as paraseptal.[1,2]

Orientation of the Atrioventricular Junctions

The right atrioventricular junction is oblique, with its free-wall component extending from superior and rightward regions toward anterior and inferior regions. In attitudinal nomenclature, its sectors can be described as right superior, right superoanterior, right anterior, right anteroinferior, and right inferior. The free wall of the left atrioventricular junction extends from left inferior through inferoposterior and posterior sectors to posterosuperior and superior sectors.[1]

This terminology describes the actual location of each sector and avoids transferring labels derived from the surgically exposed or isolated heart to the patient undergoing an electrophysiological procedure.

Septal and Paraseptal Regions

A structure is septal only when it directly separates right-sided from left-sided cardiac chambers. Many regions traditionally labelled anteroseptal or posteroseptal do not fulfil this definition. The former anteroseptal region is superior and paraseptal. The former posteroseptal region is predominantly inferior and paraseptal and includes the inferior pyramidal space, where fibro-fatty tissues extend from the inferior atrioventricular groove toward the central fibrous body.[1,2]

Within the superior paraseptal region, pathways may run close to the penetrating atrioventricular conduction axis and can be described more precisely as para-Hisian when their course and recordings support that relationship. Inferior paraseptal pathways may be approached from the right atrium, left atrium, coronary sinus, or middle cardiac vein according to their anatomical connections.[1]

Attitudinal Terminology in Procedural Practice

Attitudinal nomenclature should be applied consistently to fluoroscopy, computed tomography, magnetic resonance imaging, intracardiac echocardiography, and electroanatomical mapping. It improves communication between electrophysiologists, imagers, anatomists, and surgeons because each descriptor refers to the same direction in the patient’s body. It also reduces ambiguity when reporting catheter position, accessory pathway location, ablation targets, and neighbouring structures at risk.[1,2]