Pulsative venous return from the branchial vessels to the heart of the bivalve Mytilus galloprovincialis supports the constant-volume mechanism.

In bivalves and gastropods, ventricle contraction causes a negative pressure in the auricles and increases venous return from the afferent oblique vein (AOV): the constant-volume (CV) mechanism. The flow in the AOV should be a pulsative flow synchronized with the ventricular contraction. The flow in the heart and adjacent vessels of Mytilus galloprovincialis were measured by magnetic resonance imaging to confirm this hypothesis. Under a regular heartbeat, pulsative flows in the AOV and branchial vessels (BVs) were almost completely synchronized with the flow in the aorta, while filling of the ventricle was in the opposite phase. Flows in the BVs were directed to the posterior direction, and a pair of BVs in the gill axes (the efferent BVs) were connected to the AOV. Based on the images of the whole pathway of the AOV in an oblique slice, we confirmed that haemolymph flow was evoked from the efferent BVs and flow into the ventricle via the auricle was completed in a single heartbeat. Therefore, the walls of the AOV and BVs could resist negative transmural pressure caused by the ventricular contraction. In conclusion, the auricle, the AOV and the BVs, including the gill filaments, act as a suction pump. The pulsative venous return is driven by the negative pressure of the AOV as in the CV mechanism, and the negative pressure in the efferent BVs could draw haemolymph from the sinus via the gill and the afferent BVs. Therefore, Mytilus can start and stop its heartbeat as necessary.

The value of circular reasoning: what Harvey taught and we forgot.

William Harvey discovered that the cardiovascular system is a closed hydraulic circle. Since that discovery, many haemodynamic models have strayed by dividing the circulation into segments, which can be misleading. An alternative model is presented that both preserves circular hydraulics and provides a comprehensive picture of overall cardiovascular function using a novel cardiovascular vector graphic. The practical value of this approach resides in its ease of visualising critical physiological variables and ease of predicting and communicating how changes in those variables affect function.

Clinical Presentation and Therapy of Total Anomalous Pulmonary Venous Return.

Total anomalous pulmonary venous return (TAPVR) is rare (accounting for about 1% of all CHD) and can occur as a single lesion or in combination with other types of CHD (such as heterotaxy or HLHS). TAPVR is defined as an abnormal connection where all pulmonary veins do not drain into the left atrium but into the right atrium either directly or through a vein that is connected to the right atrium. TAPVR can be divided into four anatomic groups (Fig. 32.1): (1) supracardiac (about 55%), (2) cardiac (about 30%), (3) infracardiac (about 13%), and (4) mixed (very rare). In addition, it can be divided into two physiological types: nonobstructed and obstructed. Embryologically, all pulmonary veins usually connect to a pulmonary venous confluence that connects to the left atrium. If this connection does not occur, the pulmonary venous confluence connects to a systemic vein instead.

Inflow Tract Development.

The development of the inflow tract is undoubtedly one of the most complex remodeling events in the formation of the four-chambered heart. It involves the creation of two separate atrial chambers, the formation of an atrial/atrioventricular (AV) septal complex, the incorporation of the caval veins and coronary sinus into the right atrium, and the remodeling events that result in pulmonary venous return draining into the left atrium. In these processes, the atrioventricular mesenchymal complex, consisting of the major atrioventricular (AV) cushions, the mesenchymal cap on the primary atrial septum (pAS), and the dorsal mesenchymal protrusion (DMP), plays a crucial role.

From Other Journals: A Review of Recent Articles by Our Editorial Team.

In this review, we provide a brief description of recently published articles addressing topics relevant to pediatric cardiologists. Our hope is to provide a summary of the latest articles published recently in other journals in our field. The articles address (1) A new index for prenatal diagnosis of total anomalous pulmonary venous return, (2) Outcomes of patients with Tetralogy of Fallot after pulmonary valve replacement (PVR), and (3) Short-term outcomes of the self expanding Harmony valve for transcatheter PVR.

Rare case of total anomalous pulmonary venous return into the right atrium in situs solitus.

We report an uncommon case report of total anomalous pulmonary venous returns into the right atrium at the base of the superior caval vein's ostium without a sinus venosus defect, in situs solitus, without vertical vein or a posterior pulmonary venous confluence.

Prenatal Ultrasound Markers of Isolated Total Anomalous Pulmonary Venous Return and a Sequential Approach to Reach Diagnosis.

This article comprehensively reviews the literature concerning prenatal ultrasound findings of isolated total anomalous pulmonary venous return (TAPVR) and the application of specific sonographic markers to differentiate among the TAPVR types. These markers can be categorized as direct and indirect, based on either morphological features or hemodynamic changes in TAPVR. Indirect markers include the ventricular disproportion, an increased distance between the left atrium (LA) and the descending aorta, as well as the dilatation of superior vena cava or coronary sinus for supracardiac or cardiac TAPVR, along with abnormal pulmonary venous spectral Doppler patterns. Direct markers predominantly focus on the absence of a connection between the pulmonary veins and the LA. Some direct markers are specific to certain TAPVR types, such as the vertical vein. Diagnosing isolated TAPVR can pose challenges, but following a sequential approach can improve detection rates and outcomes. In cases with equivocal findings, additional follow-ups are recommended. The sequential approach described in the current article provides a step-wise methodology and sonographic markers for prenatal diagnosis of TAPVR, which can be utilized by fetal-maternal medicine specialists, obstetricians, and radiological technicians to ensure timely interventions.

Blood shifts between body compartments during submaximal exercise with induced expiratory flow limitation in healthy humans.

External expiratory flow limitation (EFLe) can be applied in healthy subjects to mimic the effects of chronic obstructive pulmonary disease during exercise. At maximal exercise intensity, EFLe leads to exercise intolerance owing to respiratory pump dysfunction limiting venous return. We quantified blood shifts between body compartments to determine whether such effects can be observed during submaximal exercise, when the load on the respiratory system is milder. Ten healthy men (25.2 ± 3.2 years of age, 177.3 ± 5.4 cm in height and weighing 67.4 ± 5.8 kg) exercised at 100 W (∼40% of maximal oxygen uptake) while breathing spontaneously (CTRL) or with EFLe. We measured respiratory dynamics with optoelectronic plethysmography, oesophageal (Pes ) and gastric (Pga ) pressures with balloon catheters, and blood shifting between body compartments with double body plethysmography. During exercise, EFLe resulted in the following changes: (i) greater intrabreath blood shifts between the trunk and the extremities [518 ± 221 (EFLe) vs. 224 ± 60 ml (CTRL); P < 0.001] associated with lower Pes during inspiration (r = 0.53, P < 0.001) and higher Pga during expiration (r = 0.29, P < 0.024); and (ii) a progressive pooling of blood in the trunk over time (∼700 ml after 3 min of exercise; P < 0.05), explained by a predominant effect of lower inspiratory Pes (r = 0.54, P < 0.001) over that of increased Pga . It follows that during submaximal exercise, EFLe amplifies the respiratory pump mechanism, with a prevailing contribution from lower inspiratory Pes over increased expiratory Pga , drawing blood into the trunk. Whether these results can be replicated in chronic obstructive pulmonary disease patients remains to be determined. KEY POINTS: External expiratory flow limitation (EFLe) can be applied in healthy subjects to mimic the effects of chronic obstructive pulmonary disease and safely study the mechanisms of exercise intolerance associated with the disease. At maximal exercise intensity with EFLe, exercise intolerance results from high expiratory pressures altering the respiratory pump mechanism and limiting venous return. We used double body plethysmography to quantify blood shifting between the trunk and the extremities and to examine whether the same effects occur with EFLe at submaximal exercise intensity, where the increase in expiratory pressures is milder. Our data show that during submaximal exercise, EFLe amplifies the respiratory pump mechanism, each breath producing greater blood displacements between the trunk and the extremities, with a prevailing effect from lower inspiratory intrathoracic pressure progressively drawing blood into the trunk. These results help us to understand the haemodynamic effects of respiratory pressures during submaximal exercise with expiratory flow restriction.

Volume responsiveness revisited: an observational multicenter study of continuous versus binary outcomes combining echocardiography and venous return physiology.

Echocardiography can assess cardiac preload when fluid administration is used to treat acute circulatory failure. Changes in stroke volume (SV) are inherently a continuous phenomenon relating to the pressure gradient for venous return (VRdP). However, most clinical studies have applied a binary definition based on a fractional change in SV. This study tested the hypothesis that calculating the analog mean systemic filling pressure (Pmsa) and VRdP would enhance echocardiography to describe SV responses to a preload challenge. We investigated 540 (379 males) patients during a standardized passive leg raising (PLR) maneuver. Patients were further categorized by the presence of impaired right ventricular function (impRV) or increased intra-abdominal hypertension (IAH). Multivariable linear regression identified VRdP (partial r = -0.26, P < 0.001), ventilatory-induced variations in superior vena cava diameter (partial r = 0.43, P < 0.001), and left ventricular outflow tract maximum-Doppler velocity (partial r = 0.13, P < 0.001) as independent variables associated with SV changes. The model explained 38% (P < 0.001) of the SV change in the whole cohort and 64% (P < 0.001) when excluding patients with impRV or IAH. The correlation between Pmsa or VRdP and SV changes lost statistical significance with increasing impRV or IAH. A binary definition of volume responsiveness (>10% increase in SV) generated an area under the curve of 0.79 (P < 0.001) in logistic regression but failed to identify Pmsa or VRdP as independent variables and overlooked the confounding influence of impRV and IAH. In conclusion, venous return physiology may enhance echocardiographic assessments of volume responsiveness, which should be based on continuous changes in stroke volume.NEW & NOTEWORTHY The analog mean systemic filling pressure and the pressure gradient for venous return combined with echocardiography predict continuous changes in stroke volume following a passive leg raising maneuver. The confounding effects of impaired right ventricular function and increased intra-abdominal pressure can be identified. Using a binary cutoff for the fractional change in stroke volume, common in previous clinical research, fails to identify the importance of variables relevant to venous return physiology and confounding conditions.

Evidence for a personalized early start of norepinephrine in septic shock.

During septic shock, vasopressor infusion is usually started only after having corrected the hypovolaemic component of circulatory failure, even in the most severe patients. However, earlier administration of norepinephrine, simultaneously with fluid resuscitation, should be considered in some cases. Duration and depth of hypotension strongly worsen outcomes in septic shock patients. However, the response of arterial pressure to volume expansion is inconstant, delayed, and transitory. In the case of profound, life-threatening hypotension, relying only on fluids to restore blood pressure may unduly prolong hypotension and organ hypoperfusion. Conversely, norepinephrine rapidly increases and better stabilizes arterial pressure. By binding venous adrenergic receptors, it transforms part of the unstressed blood volume into stressed blood volume. It increases the mean systemic filling pressure and increases the fluid-induced increase in mean systemic filling pressure, as observed in septic shock patients. This may improve end-organ perfusion, as shown by some animal studies. Two observational studies comparing early vs. later administration of norepinephrine in septic shock patients using a propensity score showed that early administration reduced the administered fluid volume and day-28 mortality. Conversely, in another propensity score-based study, norepinephrine administration within the first hour following shock diagnosis increased day-28 mortality. The only randomized controlled study that compared the early administration of norepinephrine alone to a placebo showed that the early continuous administration of norepinephrine at a fixed dose of 0.05 µg/kg/min, with norepinephrine added in open label, showed that shock control was achieved more often than in the placebo group. The choice of starting norepinephrine administration early should be adapted to the patient's condition. Logically, it should first be addressed to patients with profound hypotension, when the arterial tone is very low, as suggested by a low diastolic blood pressure (e.g. ≤ 40 mmHg), or by a high diastolic shock index (heart rate/diastolic blood pressure) (e.g. ≥ 3). Early administration of norepinephrine should also be considered in patients in whom fluid accumulation is likely to occur or in whom fluid accumulation would be particularly deleterious (in case of acute respiratory distress syndrome or intra-abdominal hypertension for example).

Multiple ventricular septal defects associated to anomalous venous returns, mitral valve disease, myocardium hypertrophy, and right outflow obstruction: a multimodality imaging assessment.

We report a rare congenital heart disease characterized by multiple ventricular septal defects associated to anomalous systemic and pulmonary venous returns, marked apical myocardial hypertrophy of both ventricles and of right outflow, and hypoplastic mitral anulus. Multimodality imaging is mandatory to assess anatomical details.

Multimodality diagnostic imaging for anomalous pulmonary venous connections: a pictorial essay.

Anomalous pulmonary venous connections represent a heterogeneous group of congenital heart diseases in which a part or all pulmonary venous flow drains directly or indirectly into the right atrium. Clinically, anomalous pulmonary venous connections may be silent or have variable consequences, including neonatal cyanosis, volume overload and pulmonary arterial hypertension due to the left-to-right shunt. Anomalous pulmonary venous connections are frequently associated with other congenital cardiac defects and their accurate diagnosis is crucial for treatment planning. Therefore, multimodality diagnostic imaging, comprising a combination (but not all) of echocardiography, cardiac catheterization, cardiothoracic computed tomography and cardiac magnetic resonance imaging, helps identify potential blind spots relevant to each imaging modality before treatment and achieve optimal management and monitoring. For the same reasons, diagnostic imaging evaluation using a multimodality fashion should be used after treatment. Finally, those interpreting the images should be familiar with the various surgical approaches used to repair anomalous pulmonary venous connections and the common postoperative complications.

Surgical and Cardiac Catheterization Outcomes of Scimitar Syndrome Patients: A Three Decade Single-Center Experience.

Scimitar syndrome (SS) is a rare congenital condition which includes partial anomalous pulmonary venous return (PAPVR) and a variable degree of pulmonary hypoplasia. We describe the clinical features, therapeutic approach and outcomes of patients who underwent cardiac catheterization and/or surgical repair of the scimitar vein at a single institution in the United States. This retrospective cohort study included all patients with SS who underwent scimitar vein surgical repair or cardiac catheterization from October 1989 through August 2021 in a tertiary care center. A total of 84 patients with SS were included and median follow-up time was 74 months. Patients diagnosed with SS under the age of one year had a significantly greater incidence of congenital heart defects (CHD) (p < 0.001), non-cardiac anomalies (p = 0.02), pulmonary hypertension (p = 0.02), and mortality (p = 0.04) compared to those diagnosed over the age of 1 year. Twenty-eight patients underwent surgical repair of the scimitar vein. Overall, eight (10%) patients died. Compared to surviving patients, deceased patients had a significantly higher incidence of pulmonary hypertension (PH), neonatal SS diagnosis, and extracorporeal membrane oxygenation (ECMO) support. Median scimitar vein pressure (20 mmHg) of deceased patients was significantly higher compared to pressures in surviving patients (11 mmHg; p = 0.02). PH, CHD, neonatal SS diagnosis, ECMO support, and markedly elevated scimitar vein pressure are associated with mortality. Scimitar vein surgical repair during infancy is commonly associated with PH and restenosis that requires re-intervention.

Persistent Patent Vertical Vein After Repair of Total Anomalous Pulmonary Venous Connection (TAPVR): A Rare Cause of Hypoxemia Post-Fontan Procedure.

Vertical vein (VV) ligation during total anomalous pulmonary venous return (TAPVR) repair is controversial. While some surgeons prefer ligation of the VV to prevent adverse sequelae of shunting across it and to promote flow through the newly created anastomosis, others leave it to serve as a "pop off valve" to the left heart structures, which are believed to be hypoplastic and noncompliant, presumably contributing to a more favorable post-operative outcome. We report two patients post-Fontan procedure, who underwent cardiac catheterization to explore the etiology of hypoxia and were found to have a persistent VV responsible for right to left shunting. Both patients underwent closure of the VV with improvement in the cyanosis and clinical course. These cases provide evidence supporting surgical ligation of the VV at the time of TAPVR repair, especially in patients with single ventricle.

Fetal Pulmonary Venous Return: From Basic Research to the Clinical Value of Doppler Assessment.

The fetal pulmonary circulation represents less than 25% of the fetal cardiac output. In comparison with the pulmonary arteries, studies on pulmonary veins are few and limited, and many questions remain to be answered. The literature reports that pulmonary veins play an important role in regulating vascular flow, forming an active segment of the pulmonary circulation. The development of more sophisticated ultrasonography technology has allowed the investigation of the extraparenchymal pulmonary veins and their waveform. The recognition of the pulmonary vein anatomy in echocardiography is important for the diagnosis of anomalous pulmonary venous connections, with a significant impact on prognosis. On the other hand, the identification of the normal pulmonary vein waveform seems to be a reliable way to study left heart function, with potential applicability in fetal and maternal pathology. Thus, the goal of this narrative review was to provide a clinically oriented perspective of the available literature on this topic.

The Role of the Vasculature in Heart Failure.

The contribution of the vasculature in the development and progression of heart failure (HF) syndromes is poorly understood and often neglected. Incorporating both arterial and venous systems, the vasculature plays a significant role in the regulation of blood flow throughout the body in meeting its metabolic requirements. A deterioration or imbalance between the cardiac and vascular interaction can precipitate acute decompensated HF in both preserved and reduced ejection fraction phenotypes. This is characterised by the increasingly recognised concept of ventricular-arterial coupling: a well-balanced relationship between ventricular and vascular stiffness, which has major implications in HF. Often, the cause of decompensation is unknown, with international guidelines mainly centred on arrhythmia, infection, acute coronary syndrome and its mechanical complications as common causes of decompensation; the vascular component is often underrecognised. A better understanding of the vascular contribution in cardiovascular failure can improve risk stratification, earlier diagnosis and facilitate earlier optimal treatment. This review focuses on the role of the vasculature by integrating the concepts of ventricular-arterial coupling, arterial stiffness and venous return in a failing heart.

Infradiaphragmatic partial anomalous pulmonary venous connection in adulthood. Considerations for management: a single centre experience.

BACKGROUND AND OBJECTIVES: Infradiaphragmatic partial anomalous pulmonary venous connection is occasionally diagnosed in adulthood. Management of infradiaphragmatic PAPVC depends on anatomy and clinical presentation. METHODS: Over a 10-year period, we observed seven adult patients (median age 29 years) with partial anomalous pulmonary venous connection. We classified our patients in two groups. Group I: isolated partial anomalous pulmonary venous connection from one pulmonary lobe to the inferior vena cava, three patients. Group II: partial anomalous pulmonary venous connection of the entire right lung to IVC, four patients. RESULTS: The mean term follow-up was 5.4 years. Patients in Group I have been managed conservatively, as they were asymptomatic, without a significant shunt. Patients in Group II were surgically corrected using long right intra-atrial baffles. After 6 months of follow-up, the first two cases were diagnosed with complete tunnel thrombosis and loss of right lung function. Oral anticoagulation failed to recanalize the tunnel. Considering this serious complication, the other two patients were empirically and preventively treated with anticoagulation after surgery, with good outcome on long-term follow-up. CONCLUSIONS: Conservative management should be considered for asymptomatic patients, without a significant shunt. Surgical treatment of infradiaphragmatic partial anomalous pulmonary venous connection of the entire right lung in inferior vena cava is challenging. Slow blood flow inside the long intra-atrial baffles inclines to thrombosis and occlusion, as we observed in two cases. Therefore, oral anticoagulation should be considered for long baffles with slow blood flow.

Comparison of the effects of conventional method and primary sutureless techniques on early postoperative rhythm problems in patients with total abnormal pulmonary venous return anomaly.

BACKGROUND: Total abnormal pulmonary venous return anomaly is a CHD characterised by abnormal pulmonary venous flow directed to the right atrium. In this study, we aimed to compare the effects of these techniques on early rhythm problems in total abnormal pulmonary venous return anomaly cases operated with conventional or primary sutureless techniques. METHOD: Seventy consecutive cases (median age 1 month, median weight 4 kg) who underwent total abnormal pulmonary venous return anomaly repair with conventional or primary sutureless technique between May 1 2020 and May 1 2022 were evaluated. The rate, diagnosis, and possible risk factors of postoperative arrhythmias were investigated. The results were evaluated statistically. RESULTS: When the total abnormal pulmonary venous return anomaly subgroup of 70 cases was evaluated, 40 cases were supracardiac, 18 cases were infracardiac, 7 cases were cardiac, and 5 cases were mixed type. Twenty-eight (40%) cases had a pulmonary venous obstruction. Primary sutureless technique (57%, supracardiac n = 24, mixed = 3, infracardiac = 13) was used in 40 patients. Median cardiopulmonary bypass time (110 versus 95 minutes) and median aortic clamp time (70 versus 60 minutes), median peak lactate (4.7 versus 4.8 mmol/l) in the first 72 hours, and median peak vasoactive inotropic score in the first 72 hours of the primary sutureless and conventional technique used cases value (8 versus 10) were similar. The total incidence of arrhythmias in the conventional group was significantly higher than in the primary sutureless group (46.7% versus 22.5%, p = 0.04). Supraventricular early beat was observed in 3 (7.5%), sinus tachycardia was seen in 6 (15%), junctional ectopic tachycardia was seen in 1 (2.5%), intra-atrial reentry tachycardia was seen in 1 (2.5%), usual supraventricular tachyarrhythmia was seen in 2 cases (5%) in the primary sutureless group. In the conventional group, supraventricular early beat was observed in six of the cases (20%), sinus tachycardia in five (16.7%), junctional ectopic tachycardia in four (13.3%), intra-atrial reentry tachycardia (10%) in three, and supraventricular tachyarrhythmia in seven cases (23.3%). In the first 30 days, there was a similar mortality rate (10% versus 10%), with four patients in the primary sutureless group and three in the conventional group. The median follow-up period of the cases was 8 months (interquartile range (IQR) 6-10 months). In the follow-up, arrhythmias were detected in two cases (one supraventricular tachyarrhythmia and one intra-atrial reentry tachycardia) in the primary sutureless group and three cases (two supraventricular tachyarrhythmia, one intra-atrial reentry tachycardia) in the conventional technique. All cases were converted to normal sinus rhythm with cardioversion and combined antiarrhythmic therapy. CONCLUSION: Different arrhythmias can be observed in the early period in patients with operated total abnormal pulmonary venous return anomaly. Although a higher rate of rhythm problems was observed in the early period in the conventional method compared to the primary sutureless technique, no significant effect was found on mortality and morbidity between the groups.

Long-term results of the Warden procedure for right partial anomalous pulmonary venous connection.

INTRODUCTION: Surgery is considered as the first-line therapeutic strategy of partial anomalous pulmonary venous connection. The Warden technique has very good short-term results. The aim of this study is to evaluate the stability of these good results over a long period of follow-up. MATERIALS AND METHODS: We reviewed all patients who underwent a Warden procedure for partial anomalous pulmonary venous connection between 1997 and 2017 in our centre. A total of 73 patients were included. The median age was 14 years (5 months-72 years). Post-operative data were obtained through our hospital network. Late follow-up data were obtained through referrals, cardiologist letters and directly from the patient. RESULTS: The mean length of follow-up was 8 years and the longest time was 22 years (range, 1-22). Twenty-five percent of our cohort had more than 10 years of follow-up. There were no cardio-vascular deaths. Eight (11.6%) patients suffered from post-operative rhythm disturbances, 5 (7.2%) of which were permanent. Two (2.9%) patients required a pacemaker implantation. At the end of the follow-up period, only one patient remained pacemaker dependent. There were no pulmonary vein obstructions. Two (2.9%) caval vein stenosis were detected, one at 7 months and the other at 7 years. These patients were treated by angioplasty alone. Five (6.8%) patients were lost to follow-up. CONCLUSIONS: The good short-term results of the Warden procedure for right partial anomalous pulmonary venous connection appear to persist in the long term, with excellent freedom from pulmonary and caval stenosis in adolescence through to adulthood.

Midline crossing right pulmonary veins with dual drainage to the left atrium.

We report the exceptional case of transcatheter treatment of a partial anomalous pulmonary venous drainage of the right lung to the innominate vein and dual drainage to the left atrium.