HeartMate 3 as a Bridge to Transplant in an Adult with Failing Fontan Circulation

Successful Use of the Total Artificial Heart in the Failing Fontan Circulation

Mechanical support for the failing single ventricle after Fontan

Insights into the Failing Fontan Circulation: Impact of Dominant Ventricular Morphology on Ventricular-Arterial Coupling in Adults with Fontan Circulation

COMPUTATIONAL FLUID DYNAMICS MODELS OF HEALTHY AND FAILING FONTAN CIRCULATIONS

Background Fenestration is surgically created at the time of Fontan operation, in which the extracardiac conduit is connected to the atrium through a small communication. Since the fenestration has been reported to increase venous return to the ventricle and improve the hemodynamics, the fenestration is often made when the risk of postoperative Fontan failure is high. In the failing Fontan circulation, the implantation of ventricular assist device (VAD) is sometimes required as a bridge-to-transplantation therapy. However, it has been controversial whether a closure of fenestration is necessary or not. Purpose To evaluate the effects of fenestration on the hemodynamics under VAD in the failing Fontan circulation. Methods A computational model of Fontan circulation was developed using a time-varying elastance cardiac chamber model and a modified 3-element Windkessel vasculature model. Pressure gradient through fenestration was calculated by the simplified Bernoulli’s equation. The relationship between pressure head and rotational frequency of VAD was modeled as a non-linear function. To simulate Fontan failure, ventricular end-systolic elastance was set at 1.0 mmHg/ml and then pulmonary vascular resistance index (PVRI) was varied from 3.0 to 6.8 WU m². Results In the Fontan failure model with PVRI of 3.0 WU m², mean blood pressure (MBP), cardiac index (CI) and central venous pressure (CVP) were 58.4 mmHg, 1.7 l/min/m² and 19.2 mmHg, respectively. When MBP was maintained at the same value, the 4-mm fenestration rarely affected CI (1.7 l/min/m²) and CVP (18.1 mmHg), but significantly decreased oxygen saturation (SpO2, 84.0 %). The introduction of VAD at 4000 rpm significantly increased MBP and CI in both models with/without fenestration (Fenestration (+): 93.7 mmHg, 3.2 l/min/m², Fenestration (-): 94.5 mmHg, 3.2 l/min/m²). In the model with fenestration, SpO2 recovered to 91.6 % after the VAD initiation. However, CVP slightly changed after the VAD initiation in both models with/without fenestration (18.5 and 18.9 mmHg, respectively). When stressed blood volume (SBV) was decreased until end-systolic ventricular volume became around 0 ml, CVP was decreased to the normal range (Fenestration (+): 8.3 mmHg, Fenestration (-): 10.0 mmHg). Then SBV was significantly lower in the model with fenestration than that without fenestration (-150 ml). The effects of fenestration on CVP and SBV were larger in the model with high PVRI of 6.8 WU m² (CVP: -5.5 mmHg, SBV: -460 ml) than those with PVRI of 3.0 WU m² (CVP: -1.7 mmHg, SBV: -150 ml). Conclusions Although fenestration decreases SpO2 at the onset of Fontan failure, fenestration can significantly decrease CVP and SBV under VAD support. These effects are more significant in the patients with higher PVRI. This study demonstrates that fenestration did not impair the hemodynamics under VAD support, indicating the closure of fenestration may not be necessary.

Evidence of pulmonary vascular disease after heart transplantation for Fontan circulation failure

Extracorporeal membrane oxygenator as a bridge to heart–liver en bloc transplant in a patient with Fontan circulation

BackgroundThe Fontan operation is a palliative procedure which increases the survival of patients born with an anatomical or functional univentricular circulation. The majority of individuals who have undergone Fontan palliation...

To develop an effective catheter technique to reduce the size of a Diabolo stent fenestration in the failing Fontan circulation. Diabolo stent fenestration is employed by many centers in the treatment of the failing Fontan patient. With subsequent recovery, exercise tolerance may be impaired by significant desaturation secondary to the right to left shunt across the fenestration. Complete fenestration closure carries the risk of recurrence of the initial symptoms and, hence, reduction of the size of fenestration should be the preferred technique. Twenty-eight patients with failing Fontan circulations (16 early and 12 late) underwent Diabolo stent fenestration for relief of symptoms. Five of these patients remained very limited by severe desaturation even at rest, after complete recovery from symptoms. Further cardiac catheterization with crimping/reduction of the size of the waist of the stent was carried out using a technique whereby a snare catheter was placed over the waist of the stent aided by an arterio-venous guidewire loop and a balloon catheter placed within the stent. All 5 patients had successful stent reduction with improvement in saturations, whilst still maintaining a small residual fenestration. No complications were encountered. This novel technique of reduction of a diabolo stent fenestration, in a failing Fontan circulation, offers the advantages of avoidance of implanting further devices in the circulation and the ability to redilate the stent should symptoms recur.

To investigate the effect of bosentan in patients with a failing Fontan circulation. A multicentric open label, non-controlled study. 5 tertiary care centres for congenital cardiology. We included 10 patients with a failing Fontan circulation. Their median age at inclusion was 12.12 years, with a range from 4.41 to 33,41 years. The median interval between the Fontan operation and inclusion was 7.84 years, with a range from 1.96 to 12,18 years. Participants received half the usual dose of bosentan for 4 weeks, and then the full dose for a further 12 weeks. MAIN MEASURES OF OUTCOMES: We assessed saturations of oxygen at rest and during exercise, using a 6 minutes walk test, at baseline, and during and after 16 weeks of treatment. At each visit, we assessed blood chemistry and hepatic function, and asked the patients to complete a questionnaire concerning quality of life. All medical events and possible side effects were recorded. Of the cohort, 1 patient withdrew. The changes in saturations of oxygen, exercise performance, and scores for the questionnaire did not reach statistical significance for the whole group. We noted, nonetheless, that saturations of oxygen and/or exercise capacity improved in 5 of the patients. This was further confirmed when those patients deteriorated again when the drug was discontinued. Our study failed to show significant improvement after 3 months of treatment with bosentan in a small group of patients with failing Fontan circulations. Some individuals, nonetheless, did improve. When planning larger trials, it would be better to identify those patients who might potentially benefit from the treatment prior to commencing the trial.

We investigated the results of a revision of a previous Fontan connection to total cavopulmonary connection (TCPC) in patients with failing Fontan circulation. From July 1998 to April 2013, 21 patients who had failing Fontan circulation underwent revision of the previous Fontan operation to TCPC. The median age at TCPC conversion was 17.9 years (range, 4.6-38.1 years) and the median interval between initial Fontan operation and TCPC was 13.8 years (range, 2.1-25.4 years). There were 37 indications for Fontan revision in 21 patients. The indications were huge right atrium (n = 15), atrial arrhythmia (n = 8), intra-atrial thrombi (n = 6), protein-losing enteropathy (PLE) (n = 3) and more than mild atrioventricular valve regurgitation (n = 5). The previous Fontan operation was revised to extracardiac conduit replacement (n = 20) and intra-atrial lateral tunnel (n = 1). Concomitant surgery for atrial arrhythmia was performed in 8 patients. Fenestration was performed in 7 patients. The median follow-up duration was 7.1 years (range, 0.3-13.4 years). There were no operative deaths and two late deaths occurred 7.9 and 8.1 years after operation. Actuarial 5- and 10-year survival rates were 92.3 and 83.1%, respectively. Postoperative complications included bleeding (n = 3), deep sternal infection (n = 1) and prolonged pleural effusion for more than 2 weeks (n = 5). During follow-up, atrial arrhythmia recurred in 6 patients, PLE recurred in 2 patients and pleural effusion recurred in 2 patients. All patients were classified as New York Heart Association Class I (n = 15) or Class II (n = 4). Fontan conversion to TCPC in patients with failing Fontan circulation can be performed with low risk of morbidity and mortality. The procedure confers better quality of life and is functional for patients with failed Fontan circulation.

Posterior Circulation Ischemia or Occlusion in Five Adults With Failing Fontan Circulation

First Use of HeartMate 3 in a Failing Fontan Circulation

Commentary: Management of patients with failing Fontan: More questions than answers.

Mechanical circulatory support--either ventricular assist device (VAD, left-sided systemic support) or cavopulmonary assist device (CPAD, right-sided support)--has been suggested as treatment for Fontan failure. The selection of left- versus right-sided support for failing Fontan has not been previously defined. Computer simulation and mock circulation models of pediatric Fontan patients (15-25 kg) with diastolic, systolic, and combined systolic and diastolic dysfunction were developed. The global circulatory response to assisted Fontan flow using VAD (HeartWare HVAD, Miami Lakes, FL) support, CPAD (Viscous Impeller Pump, Indianapolis, IN) support, and combined VAD and CPAD support was evaluated. Cavopulmonary assist improves failing Fontan circulation during diastolic dysfunction but preserved systolic function. In the presence of systolic dysfunction and elevated ventricular end-diastolic pressure (VEDP), VAD support augments cardiac output and diminishes VEDP, while increased preload with cavopulmonary assist may worsen circulatory status. Fontan circulation can be stabilized to biventricular values with modest cavopulmonary assist during diastolic dysfunction. Systemic VAD support may be preferable to maintain systemic output during systolic dysfunction. Both systemic and cavopulmonary support may provide best outcome during combined systolic and diastolic dysfunction. These findings may be useful to guide clinical cavopulmonary assist strategies in failing Fontan circulations.