73 Longer-Term Outcomes and Management for Patients With a Functionally Univentricular Heart
Cardiac Catheterization and Transcatheter Intervention
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Progesterone implant Not thrombogenic Long lasting (3 years) High intrinsic efficacy Progesterone intramuscular injection Not thrombogenic Long-lasting contraception (12 wk) High intrinsic efficacy Not thrombogenic Nonhormonal Additional protection against sexually transmitted infections Not thrombogenic Long-lasting contraception (5 years) Condoms/barrier methods Intrauterine device compliance Reduced efficacy with Bosentan Side effects, especially menstrual irregularity Reduced efficacy with Bosentan Small risk of hematoma with warfarin Dependent on strict 12 weekly compliance User dependency General lower efficacy Recommended Recommended Recommended ideally in conjunction with other method Potential for severe vagal Second line reaction during insertion recommendation Copper coils higher risk of menorrhagia and dysmenorrhea Infection risk, especially during insertion Cardiac Catheterization and Transcatheter Intervention In the long-term follow-up of the Fontan patient, cardiac catheterization may be indicated to close baffle or conduit fenestrations Other specific indications include the investigation and/or treatment of • unexpected systemic arterial hypoxemia, • excessive aortopulmonary collateral vessels or persistent ventricle to pulmonary connection causing pulmonary overcirculation and ventricular volume load, • the failing Fontan circulation, including those presenting with PLE or plastic bronchitis Outside these indications, the utility of routine cardiac catheterization is not well established, although some consider that knowledge of time-related trends in the CVP, systemic ventricle filling pressure, and systolic function is advantageous There is a stronger argument for intermittent imaging of the Fontan pathway and pulmonary arteries, especially in those with an extracardiac conduit With this type of Fontan circulation, the conduit portion of the pathway has a fixed length and somatic growth may stretch the pulmonary arteries toward the diaphragm, resulting in stenosis In fact, this is a rare occurrence because in most instances IVC elongation accommodates somatic growth Cardiac MRI can usually be used to obtain this information and, although it does not provide a direct measure of Fontan pathway pressure or systemic ventricle filling pressure, has the advantage of providing additional information including quantification of systemic function, assessment of proportional pulmonary blood flow, and quantification of the regurgitant fraction when valve regurgitation is present Cardiac catheterization or CT angiography can be used if MRI is contraindicated or unavailable Fenestration Closure Many patients have a fenestration created between the systemic venous pathway and the pulmonary venous atrium at the time of the Fontan procedure to reduce operative and postoperative risk (see Chapter 71) Fenestrations close spontaneously in 25% to 40% of cases.347 Those that persist can be closed with a relatively straightforward transcatheter intervention, but the benefits of closure are unclear, and timing and indications for closure are controversial (Videos 73.3 and 73.4) The fenestration allows systemic venous blood to bypass the pulmonary circulation As a result, CVP tends to be lower and cardiac output higher than would otherwise be the case Given that elevated CVP and low cardiac output are associated with many of the long-term complications of the Fontan circulation, a persistent fenestration may be advantageous in the long term However, the obligatory right-to-left shunt results in systemic arterial hypoxemia This may limit exercise capacity and contribute to myocardial fibrosis and neurologic complications In one study, an average of 30% of systemic ventricle cardiac output was provided by the fenestration when measured by cardiac MR, and in nearly two-thirds of patients, all of the inferior vena cava flow passed through the fenestration, bypassing the lungs.348 As one would expect, the amount of fenestration flow (and the degree of cyanosis) correlated with elevated pulmonary vascular resistance Interestingly it also correlated with diastolic function—the better the diastolic recoil, the more flow there was across the fenestration These findings imply that the amount of flow across the Fontan fenestration and the degree of cyanosis are poor markers of the status of the Fontan circulation A number of studies have compared the health of patients with a persistent fenestration to those without A large multicenter study demonstrated no difference in outcome measures including growth, functional health, exercise performance, and b-type natriuretic peptide.137 Likewise a single center study, in which less than a third of patients had fenestration closure at the time of review, found no difference in outcome.349 Conversely, in a population with a high rate of closure, a patent fenestration was associated with a higher risk of death (Fig 73.24).350 In that study, only a small minority of patients had a persistent fenestration and they either demonstrated unfavorable hemodynamic changes with test occlusion (see later) or were not referred for closure because of risk factors identified after the Fontan operation Perhaps most importantly the pre-