Complex interaction between the atrium and the ventricular filling process: the role of conduit

• Published in: Open heart Vol. 6; no. 2; p. e001042
• Main Authors: Marino, Paolo N, Degiovanni, Anna, Zanaboni, Jacopo
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 2019; BMJ Publishing Group
• Subjects: Cardiac arrhythmia; Heart failure; Patients; Veins & arteries; Viewpoint; diastolic dysfunction; atrial fibrillation; echocardiography
• ISSN: 2053-3624; 2398-595X; 2053-3624
• DOI: 10.1136/openhrt-2019-001042

[...]the atrial cavity has, in the past, been assigned the minimalistic role of a ‘transit chamber’, devoted exclusively to collecting and redirecting the reflux blood from the pulmonary district towards the systemic circulation. Left atrial cavity, in fact, is intimately related to ventricular function throughout the whole cardiac cycle.1 During ventricular systole, longitudinal fibre shortening forces the descent of the cardiac base, contributing to atrial filling from the pulmonary veins2 while, during diastole, the atrium passively and actively contributes to ventricular filling. Since the cavity, during early and mid-diastole, is directly exposed to the ventricular pressure through the open mitral valve, the atrial emptying pattern is obviously strongly influenced by the left heart diastolic properties.3 Atrial function can be best described by the relation between pressure and volume.4 Gathering this information, however, implies the use of a high-fidelity pressure catheter in the atrial chamber, a manoeuvre that is not performed routinely nowadays in clinical practice. Because cardiac MRI availability is limited, we employed 3D echocardiography to acquire complete and simultaneous left atrial and ventricular full-volume datasets to characterise the volume of both left-sided cardiac chambers at each time point during the cardiac cycle in order to quantify LACV (figure 1, modified from ref 8). Furthermore, those authors noticed that left atrioventricular coupling was impaired and chamber atrial compliance was reduced, in association with lower ventricular stroke volume. [...]impaired atrial compliance could provide a plausible mechanism for the observed deranged atrial conduit strain and compromised peak VO2max in the Von Roeder’s study,19 advancing the concept of an early intrinsic atrial myopathy in the genesis of HFpEF.20 Atrial stiffness and its role in heart failure The physiological significance of atrial stiffness is not completely understood, but some indirect evidence does suggest that it is important in haemodynamics.