M. J. Martinez et al.: J Extra Corpor Technol 2026, 58, 79--84 81
Fontan failure
Patients with a single ventricle have reduced and less efficient transpulmonary blood flow compared to a biventricular circulation, especially in response to increased demands such as exercise. The chronic rise in systemic venous pressure and low cardiac output are responsible for end-organ dysfunction and even permanent damage. Therefore, it is very likely that almost all patients with Fontan physiology will develop serious adverse effects of this physiology( Fontan failure), such as valve insufficiency, residual aortic obstruction, arrhythmia, coronary insufficiency, or the development of aortopulmonary collaterals. On the other hand, there may be protein-losing enteropathy, plastic bronchitis, and cyanosis. Regardless of the dominant pathophysiology, Fontan physiology can lead to liver dysfunction and cirrhosis, esophageal varices, renal dysfunction, nutritional disorders, and thromboembolic events. Some patients with poor Fontan physiology may respond to medical therapy, while in some patients with severe end-organ dysfunction, the use of mechanical circulatory support may reverse the dysfunction and improve the patient’ s condition to allow them to survive until a heart transplant [ 12, 13 ].
Materials and methods
Our case involved a 17-year-old male patient who weighed 57 kg and was 160 cm tall. He was diagnosed with ambiguous atrial situs, L-loop ventricular, L-position of the aorta, levocardia, total anomalous pulmonary venous return( TAPVR) with tricuspid atresia, transposed vessels with pulmonary atresia( IIA), heterotaxy syndrome with dextroisomerism, and levocardia. The patient had severe insufficiency in the AV valve and a dilated single ventricle with severe ventricular dysfunction. The extracardiac tube contained a permeable stent inside measuring 12 18 mm. The double Glenn procedure was performed( the right side was smaller with lower velocity).
At one year of age, the patient underwent bilateral systemicpulmonary anastomosis. At three years, a fenestrated extracardiac conduit was placed, which corrected the total anomalous pulmonary venous return, along with pulmonary branch plastic surgery and bilateral Glenn surgery. At eight years, the fenestration of the extracardiac conduit was closed. At 17 years, the patient was placed on the heart transplant list due to dysfunctional Fontan physiology with severe AV valve insufficiency and moderate to severe dysfunction of the single ventricle. In the chest X-ray( Figure 2), cardiomegaly and the stent of the extracardiac tube were evident( Figure 1).
When the patient was on the transplant list, we planned plasmapheresis during cardiopulmonary bypass and conducted a simulation in the operating room to assess the anticoagulation of both circuits, the apheresis connections with the CPB, and the management of total volumes.
For the perfusion, the Stockert S5 heart-lung machine and a Stockert 3T heat exchanger( LivaNova PLC, 20 Eastbourne Terrace, London, W2 6LG, United Kingdom) were used. A LivaNova Inspire 6F oxygenator, Sorin tubing with both venous and arterial lines( 3 / 8 00), and a hemoconcentrator DHF
02( LivaNova PLC, 20 Eastbourne Terrace, London, W2 6LG, United Kingdom) were employed.
The priming of the circuit consisted of 1000 mL of neutral pH, isosmolar polyelectrolyte solution( Rivero Laboratories, Avenida Boyacá 419( C1406BGH) Buenos Aires, Argentina), 200 mL of 20 % albumin, 100 mL of 1 M sodium bicarbonate, 1 g of cefalotin, and 10,000 IU of sodium heparin.
Due to the patient’ s elevated hematocrit( 56 %), an acute normovolemic hemodilution of 500 mL was performed prior to the start of the perfusion.
For the TPE, a Spectra Optia cellular separator was used, along with a plasmapheresis circuit with a total volume of 236 mL.
In the section of the tubing of the patient’ s venous drainage closest to the reservoir, a connector with a luer and a three-way topcock was placed to allow the blood to be diverted to the apheresis machine. After the plasma was processed and discarded, the blood, along with the replacement fluids, returned to the extracorporeal circuit through a luer connection on the reservoir, with or without a three-way topcock( Figure 3). It was important to note that the apheresis machine was primed before starting operation.
During the sternotomy, bleeding occurred due to adhesions of the heart to the bone. It was decided to initiate cardiopulmonary bypass( CPB) via the femoral artery and vein and to cool the body to 22 ° C to preserve the vital organs. After controlling the bleeding, TPE was started.
The patient’ s plasma volume was 2074 mL. It was decided to exchange this volume twice. The replacement with 1341 mL of fresh frozen plasma at a flow rate of 30 mL / min lasted 75 min. Subsequently, the replacement with 2700 mL of 5 % albumin took 60 min at a flow rate of 100 mL / min. A total of 75 mL of CDA was used as an anticoagulant. The total volume of blood processed was 8278 mL, with 4224 mL of plasma extracted. The procedure lasted 135 min and was completed before the aortic clamp was removed.
Once CPB was initiated, femoral venous cannulation and venous drainage allowed an initial flow of 2 L / min with the heart beating and the lungs ventilated. After completing the sternotomy and controlling the bleeding, central cannulation of the vessels was performed, and the temperature and pump flow were gradually increased to 32 ° C and 4.0 L / min, respectively. The patient’ s mean arterial pressure was 60 mmHg.
During CPB, six laboratory samples were taken-- three arterial and three venous-- maintaining a hematocrit of 27 %, a venous oxygen saturation of 83 %, and an average lactate level of 2 mmol / L.
Regarding anticoagulation management, the amount of heparin used in the priming was in accordance with the daily protocol. When the patient’ s temperature reached 32 ° C, 15.000 IU of heparin were added to achieve an activated clotting time( ACT) greater than 600 s. The ACT was measured according to the usual protocol, as no adverse events related to routine anticoagulation were observed during the previously mentioned simulation.
The calcium level, which was significantly low during CPB and TPE( 0.6 mmol / L) due to the CDA used in the TPE, was