Pacemaker Lead Placement via Transmural Approach in an Adult With Palliated Single Ventricle Heart Disease

Given the lack of systemic venous return to the heart, palliated single ventricle patients frequently require epicardial pacemaker implantation for management of dysrhythmias including sinus node dysfunction, atrial arrhythmias, and heart block. Repeated device hardware replacement, frequently required due to high lead thresholds or other device failure, is a challenging and significant problem for this population. 3-dimensional imaging can assist in delineating the cardiac anatomy allowing for novel approaches to intervention. We review a patient with extracardiac Fontan circulation who underwent placement of an endocardial atrial pacemaker lead via a transmural approach with a 3D-printed model used for procedural guidance.

Levoatrial Cardinal Vein: In two siblings with normal heart morphology

Levoatrial cardinal vein (LACV) is anomalous connection between the left atrium or pulmonary veins and any systemic vein which is derived from cardinal venous system. Presence of the levoatrial cardinal vein without a cardiac anomaly is a very rare congenital anomaly of the systemic venous return. In the literature, no LACV anomaly was found in two siblings who were asymptomatic and did not have an additional cardiac anomaly. Therefore, we present two cases ( two siblings ) the symptoms, diagnosis (the echocardiographic finding, computed tomography (CT) and aniographic images ) and treatment modalities of isolated levoatrial cardinal vein.

‘Misplaced’ central venous catheter in a newborn: Reminder of a common congenital anomaly

Left superior vena cava is the commonest congenital anomaly of systemic venous return. We present the case of a newborn where left jugular venous placement of central venous catheter resulted in cannulation of the left superior vena cava.

The Guytonian Equation: Established Physiological Law?

The present collection of papers is meant to focus on old and new concepts about venous return. This essay argues that one widely held old concept is wrong. The misconception would be perpetuated by those who speak of “repurposing the systemic venous return model”. The model in question describes systemic venous return as driven through a “resistance to venous return” in proportion to the difference between mean systemic pressure and right atrial pressure. It arose from experiments in which right atrial pressure (Pra) was recorded while flow was forced through the peripheral vasculature by a pump, with data points taken after pressures equilibrated to each new level of flow. The steady-state flow (F) set by the pump could be taken interchangeably as cardiac output (CO) or venous return (VR). Pra at the zero-flow level settled at what is defined as “mean systemic pressure” (Pms), understood as the pressure at which all the elastic segments of the peripheral vasculature equilibrate in the absence of pressure differences associated with flow. Total circulating volume was kept constant, independent of flow level. The data were approximated by the equation Pra = Pms – F*RVR, alternatively written as F = (Pms – Pra)/RVR. From the point of view of the first formulation, we see Pra falling in proportion to F, starting from Pms at zero flow, a concise statement of the actual experimental procedure and findings. The second formulation has been seen from a different perspective; that F is proportional to the net driving pressure, i.e., (Pms – Pra), in which Pra is seen as a back pressure opposing venous return. From this point of view, adopted by a leading researcher of his time, A.C. Guyton, comes the idea that, to increase VR, the heart must somehow reduce Pra. Re-examining the model that Guyton and his coworkers developed reveals that the appearance of Pms in their equation does not identify this variable as a pressure that exists physically at the upstream end of the pathway for venous return. At best, the model offers a way of looking at the factors that determine the equilibrium between the Pra that results in the peripheral vasculature at a particular steady-state level of flow that is consistent with the influence of Pra on the output of the heart. It has nothing to offer for the advancement of understanding of the pathophysiology of real, dynamic flow within vascular segments.

Fundamental physiologic concepts of venous hemodynamics and systemic venous return

Understanding the nominal venous anatomy and venous hemodynamics is the first and fundamental step in understanding the pathophysiology of venous disorders. Over the last two decades, significant effort has gone into improving the management of chronic venous disorders resulting in substantial improvement in the management of patients affected by venous insufficiency. Given the continuity of the venous system especially pertinent to the relationship between thoracic, abdominal, pelvic, and infrainguinal venous anatomy, combined with the increasing knowledge we gained regarding hemodynamics of the venous system it is imperative that a comprehensive approach to venous disorders is undertaken that evaluates venous system as a continuum rather than an approach that would evaluate only isolated venous territory affected by a specific venous disorder. Understanding of venous anatomy and physiology, as the basic components for venous hemodynamics, is an essential step to gain insights into venous return concepts, initially described by Dr. Guyton. Dr. Guyton's model represents a fundamental and one of the most significant advancements in our understanding of venous return. This manuscript details essential domains of hemodynamics, which can be useful for validation of our current understanding of systemic venous return.

Congenital systemic venous return anomalies to the right atrium review

Congenital anomalies of the systemic venous return to the right atrium are rare and stem from variations in the embryogenesis of the venous system. They are usually asymptomatic, and such the major clinical significance of their recognition is to prevent misdiagnosis, in addition to some having technical implications on invasive procedures.Typically, the venous blood from the upper half of the body is carried by the right-sided, superior vena cava (SVC), and some common congenital abnormalities found are persistent left SVC, SVC duplication, anomalous drainage of the brachiocephalic veins, or interruption of the SVC. The venous blood from the lower body is carried by the right-sided, inferior vena cava (IVC), and some common congenital abnormalities found are left-sided IVC, IVC duplication, the absence of IVC (total or just the infrarenal segment), and azygos continuation of the IVC. The azygos system of veins, running up the side of the thoracic vertebral column, connects both systems and can provide an alternative path to the right atrium when either of the venae cavae is absent. Other associated azygos-hemiazygos system anomalies are the azygos lobe and variable configuration of the azygos and hemiazygos veins.Such anomalies are reviewed with particular respect to their embryology and imagiological presentation, as knowledge of the normal anatomy and the most common congenital anomalies of the systemic venous return by a radiologist is important, being incidentally found.