Two-ventricle Circulation Research Articles

Cardiac Catheterisation Interventions in Neonates and Infants Less Than Three Months.

IntroductionPediatric cardiac catheterization interventions become an established way of care for selected patients with congenital heart diseases. Cardiac catheterization for neonates and small infants can be challenging. The indications for diagnostic cardiac catheterization have decreased with the advent of advanced non-invasive imaging modalities.Patients and methodBetween June 2012 and July 2017 patients less than three months who had cardiac catheterization in two centers were reviewedResultsDuring the study period, 174 patients underwent interventional cardiac catheterization,83.3% of them had CHD with two-ventricle circulation and 29 patients (16.7%) had single ventricle pathophysiology. Procedures include diagnostic cath, BAS, balloon pulmonary and aortic valvuloplasty, coarctation angioplasty, and stenting procedures. The vascular access depends upon the type of procedure. All except one had general anesthesia. ICU admission was required on 106 patients (62%). Patients were divided according to the type of cardiac lesion (single versus biventricular pathology) as well as according to the type of intervention (stenting and non-stenting procedures). Comparing these groups revealed that: stent procedures and procedures for patients with single ventricle pathologies were performed at an earlier age, with more contrast, fluoro and procedure time than for non-stent procedures and procedures for patients with biventricular pathologies. Complications include transient arrhythmias in most patients, perforation of the RVOT in one and lower limb hypoperfusion in 12 patients. ICU complications include low cardiac output symptoms (LCOS) in 10 (7%), and sepsis in 8. No intra-procedure mortality. The overall survival was 94%. Ten patients died, with one early and 9 late mortality. 60% of the dead patients had PDA stenting. Reintervention varies according to the patient's diagnosis.ConclusionCardiac catheterization intervention an important modality in the management of neonates and infants with critical CHD. Well planned procedures and team expertise are essential. Stenting procedures and procedures for patients with single ventricles carries higher morbidity and mortality.

Case-based approach to demonstrate utility of cardiac magnetic resonance imaging (MRI) for planning biventricular repair with inconclusive echo: illustration of two cases.

Congenital heart defects that present earlier in life and involving a hypoplastic ventricle are sometimes channeled towards single-ventricle repair because of anatomical or logistic challenges (1). With the single-ventricular repair, the final result is the shunting of venous return directly into the pulmonary artery and the utilization of the functioning ventricle for systemic circulation (2). Though singleventricular repair has remarkable short-term results, long-term survivors experience declines in exercise tolerance, heart failure, arrhythmias, and thromboembolic complications (3). Given long-term functional and survival advantages of a two-ventricle circulation, exploring feasibility of biventricular repair is essential for improving prognosis. However, a successful biventricular repair requires sufficiently functioning ventricles to sustain a balanced flow through the pulmonary and systemic circuit. To evaluate the functional adequacy of the ventricle with hypoplasia, echocardiogram is conventionally used.

Multiblock High Order Large Eddy Simulation of Powered Fontan Hemodynamics: Towards Computational Surgery.

Children born with only one functional ventricle must typically undergo a series of three surgeries to obtain the so-called Fontan circulation in which the blood coming from the body passively flows from the Vena Cavae (VCs) to the Pulmonary Arteries (PAs) through the Total Cavopulmonary Connection (TCPC). The circulation is inherently inefficient due to the lack of a subpulmonary ventricle. Survivors face the risk of circulatory sequelae and eventual failure for the duration of their lives. Current efforts are focused on improving the outcomes of Fontan palliation, either passively by optimizing the TCPC, or actively by using mechanical support. We are working on a chronic implant that would be placed at the junction of the TCPC, and would provide the necessary pressure augmentation to re-establish a circulation that recapitulates a normal two-ventricle circulation. This implant is based on the Von Karman viscous pump and consists of a vaned impeller that rotates inside the TCPC. To evaluate the performance of such a device, and to study the flow features induced by the presence of the pump, Computational Fluid Dynamics (CFD) is used. CFD has become an important tool to understand hemodynamics owing to the possibility of simulating quickly a large number of designs and flow conditions without any harm for patients. The transitional and unsteady nature of the flow can make accurate simulations challenging. We developed and in-house high order Large Eddy Simulation (LES) solver coupled to a recent Immersed Boundary Method (IBM) to handle complex geometries. Multiblock capability is added to the solver to allow for efficient simulations of complex patient specific geometries. Blood simulations are performed in a complex patient specific TCPC geometry. In this study, simulations without mechanical assist are performed, as well as after virtual implantation of the temporary and chronic implants being developed. Instantaneous flow structures, hepatic factor distribution, and statistical data are presented for all three cases.

Use of ACE inhibitors in Fontan: Rational or irrational?

BackgroundDespite a lack of evidence supporting the use of angiotensin-converting enzyme (ACE) inhibitors in patients with a Fontan circulation, their use is frequent. We decided to identify the rationale for ACE inhibitor therapy in patients within the Australia and New Zealand Fontan Registry. MethodsAll patients in the Registry taking an ACE inhibitor at last follow up were identified, and a review of medical records was undertaken to determine the rationale for treatment initiation and reasons for treatment continuation or dose increase. ResultsIn 2015, 36% of the surviving patients in the Registry (462/1268) were taking an ACE inhibitor. Indications for initiation of therapy were ventricular systolic or diastolic dysfunction (29%), atrioventricular valve regurgitation (19%), preservation of normal ventricular function (7%), prolonged effusions at Fontan (6%), hypertension (6%), other (6%) and unknown (2%). No indication was stated in the remaining patients (25%). Those with hypoplastic left heart syndrome were more likely to be on an ACE inhibitor than those with an alternative primary morphology (70% vs 32%; p<0.001). Only 36% of the patients treated with an ACE inhibitor at last follow up (166/462) had an indication that would generally justify treatment in a two-ventricle circulation. ConclusionIt is likely that the use of ACE inhibitors in patients with a Fontan circulation is excessive within our region. The coordination of prospective, multicentre studies and initiatives such as the Australia and New Zealand Fontan Registry will facilitate further investigations to guide treatment decisions in the growing Fontan population.

Abstract 12727: The Clinical Impact of Eicosapentaenoic Acid/Arachidonic Acid Ratio in Adult Patients With Congenital Heart Disease

Background: Recent studies showed that intake of long-chain n-3 polyunsaturated fatty acids reduces the incidence of cardiovascular events. Furthermore, low levels of eicosapentaenoic acid (EPA) are associated with heart failure (HF), arrhythmia, and cardiac sudden death. However, there have been few studies regarding the clinical implication of the EPA/arachidonic acid (AA) ratio in adult patients with congenital heart disease (CHD). Objectives and methods: The present study was a prospective study of 64 adult patients with CHD. We measured serum EPA and AA and divided the patients into two groups according to their EPA/AA ratio: &lt;0.25, low group; ≥0.25, high group. Patients were observed for a mean duration of 13 months. We investigated the association between the EPA/AA ratio and clinical data and analyzed the prognostic predictive value of the EPA/AA ratio in these patients. Results: There were no significant differences between the low (n = 36) and high (n = 28) groups in age, sex, blood pressure, systemic ventricular ejection fraction, medications, or serum levels of hemoglobin A1c, creatinine, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, triglyceride, or B-type natriuretic peptide. A low EPA/AA ratio had significant prognostic value for arrhythmia (hazard ratio [HR] 3.6, 95% confidence interval [CI] 1.1-14.8, p = 0.03) and composite events of arrhythmia and HF hospitalization (HR 5.6, 95% CI 1.53-27.8, p &lt; 0.01). Subgroup analysis revealed that the patients with two-ventricle circulation in the low group (n = 23) were at significantly higher risk of arrhythmia (HR 6.7, p = 0.02), HF hospitalization (HR 16.2, p &lt; 0.01), and composite events of arrhythmia and HF hospitalization (HR 6.7, p = 0.03) than those in the high group (n = 23). In patients with single-ventricle circulation, serum EPA levels were significantly lower compared with patients with two-ventricle circulation. Conclusions: The EPA/AA ratio had a significant predictive value for cardiac events in adult patients with CHD, especially in patients with two-ventricle circulation. The effect of EPA treatment for patients with CHD should be elucidated in the future.

Is alternative cardiac surgery an option in adults with congenital heart disease referred for thoracic organ transplantation?†

We analysed the outcomes of adults with congenital heart disease (ACHD) referred for thoracic organ transplantation who underwent non-transplant cardiac surgery as an alternative management option. Adult patients with congenital heart disease assessed for heart or heart-lung transplant were identified from the departmental database. A retrospective analysis of the medical records, transplant assessment data and surgical notes was carried out. One hundred and twenty-six patients were assessed between January 2000 and July 2011. Non-transplant cardiac surgery was performed in 14 (11%) patients. There were nine males with a median age of 37 years (range 21-42). The patients can be divided into four subgroups [left-sided lesions (n = 4), right-sided lesions (n = 3), systemic right ventricle (n = 5) and Fontan circulation (n = 2)]. Surgical procedures performed were: relief of systemic obstructive/regurgitant lesions ± endocardial fibroelastosis resection (n = 4, three pulmonary vascular resistance >6 Wood units), correction of right-sided regurgitant/stenotic lesions (n = 3), ventricular assist device for patients with a systemic right ventricle (n = 5) and re-fashioning of the Fontan pathway (n = 2). There were two early (5 and 30 days) and three late deaths (64, 232 and 374 days) with a 1-year mortality of 28%. None of the deaths occurred in patients with a two-ventricle circulation and atrio-ventricular concordance. Nine patients are alive at a median of 433 days (range 204-2456). The New York Heart Association class has improved in all survivors by at least one class at 3 and 6 months (P = 0.004 and 0.003). Alternative cardiac surgery can be undertaken in selected patients with ACHD referred for cardiopulmonary transplantation with a low mortality in patients with two ventricles and a systemic left ventricle. Ventricular assist devices carry a significant mortality in patients with a systemic right ventricle, although this offers a valuable palliation when there are no other options. The medium and long-term results are awaited.

Hybrid Therapy for Pulmonary Atresia With Intact Ventricular Septum

In patients with pulmonary atresia with intact ventricular septum without right ventricular-dependent coronary circulation, catheter techniques, including the use of a stiff wire, lasers, and radiofrequency, have been most widely used for initial therapy; however, percutaneous perforation and balloon valvuloplasty have been associated with higher rates of procedural failure and serious complications. We report our experience with a hybrid approach involving the combination of surgery and interventional catheterization techniques for right ventricular decompression. Between March 2005 and April 2010, we performed a hybrid procedure in 30 newborns and infants (age, 1 day to 2 years; median age, 3 months) with favorable anatomy. The heart was exposed by performing midline sternotomy. A purse-string suture was placed in the right ventricular outflow tract 2 cm away from the pulmonary trunk. Then, a 16-gauge intravenous catheter was placed periventricular with the guidance of echocardiography to perforate the atretic pulmonary ventricle. Subsequently, a guide wire was inserted into the sheath and used to guide a balloon across the pulmonary ventricle. Sequential dilations were performed under the guidance of epicardial echocardiography until full opening of the pulmonary ventricle was obtained. In newborns, ductal ligation was performed, followed by modified Blalock-Taussig (mBT) shunt placement. Patients aged greater than 1 month were treated mostly with ductal ligation, and an mBT shunt was inserted if severe systemic oxygen desaturation occurred after ductal ligation; bidirectional Glenn shunt placement was performed if a patient showed severe hypoplasia. The hybrid procedure was successfully performed in all patients. Patent ductus arteriosus ligation was simultaneously performed in 27 cases. Six newborns were treated with mBT shunt placement after pulmonary valvuloplasty and patent ductus arteriosus ligation, and 2 patients aged greater than 1 month were treated with mBT shunt placement alone. Another 2 patients were selected for univentricular palliation with bidirectional Glenn procedure because of a diminutive monopartite right ventricle. No pericardial effusion or cardiac tamponade was observed. One patient in whom ductal ligation could not be performed was treated with mBT shunt placement because of hypoxemia 3 days after the hybrid procedure; the other patients were discharged without any further surgical intervention. During the follow-up period of 1.5 months to 5 years, 5 patients died; 25 (83.3%) survived and all were in New York Heart Association functional class 1. Saturation of peripheral oxygen in the survivors increased from 73.1±8.5% to 94±3.5% (p<001). Two-ventricle circulation was achieved in 24 patients, whereas 1 patient had a single-ventricle pathway. In conclusion, periventricular balloon pulmonary valvuloplasty using a hybrid approach was safe and feasible for patients with pulmonary atresia with intact ventricular septum.

The in-utero development and treatment of Pulmonary Atresia with intact septum

Pulmonary Atresia with intact septum can be diagnosed by echocardiography from early pregnancy where a spectrum of morphology can be recognised. Important tricuspid regurgitation is common and the right ventricle develops at supra-systemic pressures leading to progressive ventricular hypertrophy and mineralisation that can be seen on serial echocardiograms. This is likely to compromise later ventricular function and only about a third of children achieve an eventual two-ventricle circulation. Fetal valvuloplasty has been proposed as a potential therapy to open the pulmonary valve, reduce right ventricular pressure and improve the potential for normal myocardial development. There is no evidence yet, however, that fetal pulmonary valvuloplasty alters the growth of the pulmonary or tricuspid valves or influences the ventricular size to change the eventual designation, although theoretical benefits in quality of the myocardium may lead to improved outcomes.

Mechanical Cavopulmonary Assist for the Univentricular Fontan Circulation Using a Novel Folding Propeller Blood Pump

A blood pump specifically designed to operate in the unique anatomic and physiologic conditions of a cavopulmonary connection has never been developed. Mechanical augmentation of cavopulmonary blood flow in a univentricular circulation would reduce systemic venous pressure, increase preload to the single ventricle, and temporarily reproduce a scenario analogous to the normal two-ventricle circulation. We hypothesize that a folding propeller blood pump would function optimally in this cavopulmonary circulation. The hydraulic performance of a two-bladed propeller prototype was characterized in an experimental flow loop using a blood analog fluid for 0.5-3.5 lpm at rotational speeds of 3,600-4,000 rpm. We also created five distinctive blood pump designs and evaluated their hydraulic performance using computational fluid dynamics (CFD). The two-bladed prototype performed well over the design range of 0.5-3.5 lpm, producing physiologic pressure rises of 5-18 mm Hg. Building upon this proof-of-concept testing, the CFD analysis of the five numerical models predicted a physiologic pressure range of 5-40 mm Hg over 0.5-4 lpm for rotational speeds of 3,000-7,000 rpm. These preliminary propeller designs and the two-bladed prototype achieved the expected hydraulic performance. Optimization of these configurations will reduce fluid stress levels, remove regions of recirculation, and improve the hydraulic performance of the folding propeller. This propeller design produces the physiologic pressures and flows that are in the ideal range to mechanically support the cavopulmonary circulation and represents an exciting new therapeutic option for the support of a univentricular Fontan circulation.

Cardiac Rest and Reserve Function in Patients With Fontan Circulation

In the present study, we systematically tested cardiac rest and reserve function in patients with Fontan physiology to check for inherent limitations of this circulation. Details of the mechanisms of cardiac performance that could account for adverse outcome after Fontan surgery are not well understood. The subjects were 17 Fontan patients with good functional status (Fontan group) and 20 patients with normal two-ventricle circulation (control group). We examined baseline ventricular contractility, diastolic function, and loading factors, and examined changes in those parameters in response to increased heart rate (HR) due to atrial pacing and in response to beta-adrenergic stimulation, using ventricular pressure-area relationships during preload reduction. At baseline, the Fontan patients exhibited minimal abnormality of cardiac properties, but the significant increase in afterload resulted in decreased cardiac index. In addition, Fontan circulation was associated with limited inotropic response and worsening of diastolic filling with increased HR, leading to decreased systolic pressure and elevation of central venous pressure at higher HRs (p < 0.05 vs. control). Furthermore, beta-adrenergic reserve was markedly decreased in the Fontan group, compared with controls, owing to limited preload reserve rather than limited contractile reserve. Because normal ventricular-vascular interaction and augmentation of cardiac performance during increased HR and adrenergic stimulation are important for maintaining cardiac output and exercise capacity, the present results may have important implications for the mechanisms underlying adverse outcome after Fontan surgery. Thus, improvement of long-term prognosis of patients after Fontan surgery requires the development of medical interventions that can overcome such limitations inherent in Fontan circulation.

In‐utero intervention for hypoplastic left heart syndrome — a perinatologist's perspective

.Today,whenHLHSisdiagnosedinthenewborn,or suspected by prenatal ultrasound studies, surgicalinterventions typically take one of two directions – eitherthe multistaged reconstruction pioneered by Norwood toenable single ventricle survival or cardiac transplantation.Compassionate care, although increasingly controversial,remains an option in some centers. Although increasingsurvival rates following both multi-staged surgery ortransplant are being reported, the nature of theseinterventions is such that these children remain at lifelongrisk for cardiac and neurologic morbidity.Consideration of HLHS as a candidate for

Advances in fetal cardiac intervention.

Fetal cardiac intervention is in a rapid state of progress now. Attempts are being made to prevent fetal hydrops due to congenital heart defects, to recruit hypoplastic ventricles, to create a two-ventricle circulation after birth, and to remodel the fetal pulmonary vascular bed whose outlet is obstructed. Open heart surgery in the fetus has yet to be done successfully, but interventions for improved cardiac outcomes are now being tested. Their outcomes will depend, in large part, on their successful physiological effects. How to measure these and quantitate the effects of our interventions will require further advances in the understanding of these diseases-both their natural and unnatural courses. New ultrasound techniques and assessment tools to assess fetal cardiac wellness could enhance the limited progress in fetal intervention in the heart so far.

Ventricular afterload and ventricular work in Fontan circulation: comparison with normal two-ventricle circulation and single-ventricle circulation with Blalock-Taussig shunts

Ventricular afterload and ventricular work in Fontan circulation: comparison with normal two-ventricle circulation and single-ventricle circulation with Blalock-Taussig shunts

Valvulotomía pulmonar percutánea mediante radiofrecuencia en la atresia pulmonar con septo interventricular íntegro

Early pulmonary valvulotomy in patients with pulmonary atresia and intact interventricular septum allows the development and growth of the right ventricle and two-ventricle circulation. Percutaneous valvulotomy today is a valid alternative procedure to surgical valvulotomy. With the use of the radiofrequency 5F currently available for the treatment of arrythmias atretic pulmonary valve perforation and consecutive balloon dilation may be safely and effectively performed. We describe a case of perforation of a pulmonary valve by radiofrequency in a 15-day-old neonate with pulmonary valve atresia and intact ventricular septum.

Growth of the right ventricle after successful transcatheter pulmonary valvotomy in neonates and infants with pulmonary atresia and intact ventricular septum

Objectives: Since 1990, transcatheter pulmonary valvotomy has become an alternative to surgical valvotomy in the management of neonates and infants with pulmonary atresia and intact ventricular septum. We sought to determine whether right ventricular growth after transcatheter pulmonary valvotomy is commensurate with body growth. Methods: Laser or radiofrequency-assisted balloon valvotomy was attempted in 12 neonates and infants with pulmonary atresia and intact ventricular septum. Tricuspid and mitral valve dimensions were measured retrospectively on the cross-sectional echocardiograms performed before the procedure and during follow-up. Z-values were used to standardize tricuspid valve dimensions with body size. Results: The atretic pulmonary valve was successfully perforated and dilated in nine of 12 patients. Five of these nine patients required additional transcatheter or surgical procedures to augment the pulmonary blood flow. Of six survivors, five are regularly followed up with a median follow-up of 60 months (range 37 to 68 months). All five have two-ventricle circulation, two of the five patients requiring surgical enlargement of the right ventricular outflow tract with or without closure of the atrial septal defect. Echocardiographic tricuspid valve dimensions and Z-values before transcatheter valvotomy tended to be smaller in the patients who died than in the survivors. In the survivors, the absolute tricuspid valve dimensions increased after valvotomy but the Z-values tended to decrease or stayed constant. Conclusions: Transcatheter valvotomy is a good alternative to surgical valvotomy in patients with pulmonary atresia and intact ventricular septum. Two-ventricle circulation can be achieved despite subnormal right ventricular growth. (J Thorac Cardiavasc Surg 1998;115:1055-62)