Patients who have undergone Fontan palliation are known to have higher risk of thromboembolic events. However, documented embolic myocardial infarction is very unusual. We present such a case presenting with symptomatic acute heart failure related to thromboembolic myocardial infarction. This case is also novel, in that this is the first report of successful support of a patient with Fontan physiology with an Impella device as a bridge to stabilization and eventual transplantation.
Our patient is a 17 year-old male with diagnosis of tricuspid atresia and coarctation of the aorta, status post-staged single ventricle palliation, with an eventual extracardiac fenestrated Fontan completion at 1.5 years of age. Further interventions include occlusion of venovenous collaterals at 10 years of age. He did well thence without evidence of arrhythmias, ventricular dysfunction, or liver dysfunction.
He presented acutely after having several hours of chest pain and shortness of breath at home. His initial evaluation in the local emergency room revealed ST-segment elevation on electrocardiogram (ECG) and elevated troponin levels. He was given aspirin and clopidogrel and started on intermittent nitroglycerin and heparin infusion. He was transferred to the cardiac intensive care unit at Children’s Healthcare of Atlanta, Emory University, approximately 12 hours after the onset of his symptoms. On admission, he was symptomatic with chest pain, diaphoresis, ECG changes (Q waves in the lateral leads and ST-segment elevation in the anterolateral leads), and elevated troponin (peak of >200 ng/ml, normal <0.045 ng/ml) and creatinine kinase (CKMB) (109.9 ng/ml, normal <3.6 ng/ml). An echocardiogram revealed an ejection fraction of <10% with akinesis of significant portion of the left ventricular wall. This was compared with previously documented normal left ventricular systolic function with ejection fraction of approximately 55% at previous visit. He was taken to the catheterization laboratory. Cardiac catheterization demonstrated left ventricular end-diastolic pressure of 18 mm Hg. Fontan fenestration was not patent. Coronary angiography revealed a saddle embolus in the left anterior descending coronary artery trifurcation (Figure 1A) with some extension into the branches. He underwent balloon angioplasty of the vessels (Figure 1B) using a 2.5 mm × 15 mm TREK coronary balloon catheter (Abbott Laboratories, Abbott Park, IL). An EXPORT aspiration catheter (Medtronic Inc., Minnesota, MN) was advanced with removal of clot and fibrous debris. Intracoronary thrombolysis was performed using tissue plasminogen activator with nitroglycerin, with successful reperfusion of his left anterior descending (Figure 1C; Supplemental Digital Content 1–4, http://links.lww.com/ASAIO/A92, http://links.lww.com/ASAIO/A93, http://links.lww.com/ASAIO/A94, http://links.lww.com/ASAIO/A95). He was treated with milrinone, as well as nitroglycerin. He however continued to be in extremis because of low cardiac output syndrome with a single ventricle physiology. This was reflected by rapidly rising brain-type natriuretic peptide, which peaked at 2,877 pg/ml (normal <100 pg/ml), as well as the aforementioned troponin levels of >200 ng/ml.
Decision was made to provide temporary hemodynamic support and unloading by using mechanical circulatory support. Mechanical support was therefore initiated with a 2.5 L Impella (Abiomed Inc, Danvers, MA) as a means of temporary circulatory support. The intended use was bridge to recovery or decision, to allow time for transplant candidacy evaluation. In brief, Impella 2.5 is a 12 French (Fr) microaxial pump mounted on a 9 Fr catheter. By design, the pump can generate up to 2.5 L/min of output at the maximum speed of 51,000 rpm/min. The device was inserted via the right Femoral artery using a modified Seldinger technique. The pump was advanced across the aortic valve into the left ventricle under fluoroscopy guidance (Figure 1D). Systemic anticoagulation was achieved using a unfractionated heparin to maintain activated thrombin time of 160–180 seconds per manufacturer recommendations. He was successfully supported with close monitoring for the following 6 days. Initiation of Impella support was associated with resolution of chest pain, respiratory effort, and reduction in the resting heart rate from 160 to 130 bpm. During this time, there was rapid decline in the troponin and CKMB. Echocardiogram, however, did not demonstrate any improvement in the cardiac function. There was significant dyssynchrony with severely decreased systolic function, calculated ejection fraction of 17% (accuracy limited by wall motion abnormalities). During this time, he was evaluated and enlisted for heart transplantation. After 6 days of circulatory support, we started weaning trials for Impella to assess the need for transition to a long-term device for support. However, he was successfully weaned and he was maintained on inotropic support with milrinone at 0.7 μg/kg/min, oxygen, anticoagulation but with NYHA class IV symptoms. Eight days after discontinuation of the Impella support, he underwent a successful heart transplantation. One year post-transplant, he continues to do well clinically.
The Fontan procedure was first described in the 1970s for palliation of tricuspid atresia. Its use has been expanded to include other univentricular hearts. Although it helped palliate this otherwise deadly diagnosis, late morbidity and mortality have continued to affect these patients.1 A recent study demonstrated 10, 20, and 30 year survival to be 74%, 61%, and 43%, respectively.2
As patients with single ventricle physiology age, various studies have identified arrhythmias, protein-losing enteropathy (PLE), heart failure, and need for reoperations as causes of morbidity and mortality.1,2 In addition, risk for thromboembolic events has been identified as a major source of morbidity and mortality. Suggested risk factors for venous and arterial thrombi and thromboembolism include, but are not limited to, venous stasis, atrial arrhythmias, and PLE.3 Our patient was approximately 16 years since his Fontan procedure and had an uneventful postoperative course. He was regularly followed without evidence of arrhythmias, poor cardiac function, or liver dysfunction. Although sudden death and death because of unknown reasons may be attributable to myocardial infarction in patients with Fontan, actual documentation of thromboembolic myocardial infarction is rare. Literature search yielded two cases reported in the 1990s describing myocardial infarction in patients after fenestrated Fontan, one patient as young as 3 years.4
Although the formation of thrombi has been quoted as high as >15%, the degree of anticoagulation necessary for this patient population is still under debate. Cardiologists determine the need for chronic anticoagulation based on the type of Fontan palliation, presence of right to left shunting, cardiac arrhythmias, and poor cardiac function. There is a significant variation in practice among centers and providers as far as anticoagulation and antiplatelet therapy is concerned. A recent meta-analysis showed that there was no difference in thromboembolic outcomes, between Fontan patients treated with warfarin anticoagulation or antiplatelet therapy (generally with aspirin). In general, any prophylaxis is deemed better than no prophylaxis.5 Our patients are routinely placed on prophylaxis with Aspirin 81 mg daily, only.
Other novel aspect of the case is the temporary support of this single ventricle patient with Impella 2.5 (Abiomed Inc). Impella is being increasing used in adults with high-risk coronary interventions or in cases of cardiogenic shock.6 The use of any form of circulatory support device in patients with Fontan (either short- or long-term) has shown only limited success.5 Various factors contribute to the failure including the difficulty with meeting the preload needs of a ventricular assist device (VAD), high venous pressures, variable systemic vascular resistance, and underlying coagulopathy. There are added and significant surgical limitations that are unique to this population. A percutaneous device with lower net flow but with flow characteristics that are amenable to the Fontan circulatory physiology is a reasonable option in a state of low cardiac or cardiogenic shock. As demonstrated by our case, Impella can be successfully used as a bridge to recovery or transplantation in this group of patients.
This case underscores the importance of having coronary embolism as a differential diagnosis when a palliated single ventricle patient presents with shortness of breath and chest pain, no matter the age. The case presents the possibility of mechanical support with percutaneous device such as Impella for the treatment of low cardiac output syndrome as a bridge to recovery or decision.
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2. Pundi KN, Johnson JN, Dearani JA, et al.40-Year follow-up after the Fontan operation: Long-term outcomes of 1,052 patients.J Am Coll Cardiol20156617001710
3. Firdouse M, Agarwal A, Chan AK, Mondal TThrombosis and thromboembolic complications in Fontan patients: A literature review.Clin Appl Thromb Hemost201420484492
4. Wilson DG, Wisheart JD, Stuart AGSystemic thromboembolism leading to myocardial infarction and stroke after fenestrated total cavopulmonary connection.Br Heart J199573483485
5. Marrone C, Galasso G, Piccolo R, et al.Antiplatelet versus anticoagulation therapy after extracardiac conduit Fontan: A systematic review and meta-analysis.Pediatr Cardiol2011323239
6. O’Neill WW, Schreiber T, Wohns DH, et al.The current use of Impella 2.5 in acute myocardial infarction complicated by cardiogenic shock: Results from the USpella Registry.J Interv Cardiol201427111