Continuous Aortic Flow Augmentation in a Chronic Heart Failure Patient With Peripheral Arterial Disease

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Heart failure (HF) is a growing problem worldwide and is associated with high rates of morbidity and mortality. More than 5 million Americans—and 14 million persons worldwide—experience HF.1 These patients are characterized by progressive health deterioration and increasingly frequent episodes of decompensation, often resulting in repeat hospital admissions. In the United States, more than 1 million hospitalizations a year are due to decompensation of HF, resulting in an enormous economic burden for health care systems.2 Furthermore, hospitalization represents more than 50% of the direct and indirect costs of HF. Although medical therapy for HF has advanced substantially, up to 20% of patients hospitalized with HF no longer respond to standard medical (drug) therapy.3 Patients with decompensated HF who are refractory to standard medical management are known to have a poor prognosis and a detrimental impact on health care resources. Numerous studies have established a key role of neurohormonal mechanisms as mediators for the progression of HF. It has been speculated that one of the reasons for the vicious cascade of adverse neurohormonal activation is reduced aortic blood flow due to the low cardiac output in HF.4 Disordered aortic flow is not merely "low flow" but is a chaotic disturbance in the flow "signature" within the aorta. Disordered aortic flow, with flow reversal at the endothelial margin during portions of the cardiac cycle, has been previously characterized in bench top and animal models and is thought to be an important contributing factor to HF and the cardiorenal syndrome.5 Supporting this hypothesis, continuous aortic flow augmentation (CAFA) has been reported in a feasibility study to reduce pulmonary capillary wedge pressure, improve renal function, improve the Starling curve, and reduce systemic vascular resistance during the treatment period as well as after removal of the system.6 CAFA addresses the problem of disordered aortic flow by superimposing continuous flow on pulsatile flow in the descending aorta throughout the cardiac cycle. Therefore, CAFA might be an option to interrupt the cardiorenal syndrome by improving endothelial function and down-regulating neurohormones in patients with truly refractory HF and without further therapeutic options. Implantation of the percutaneous Cancion System (Orqis Medical Corporation, Lake Forest, CA) provides CAFA to treat decompensated HF. The Cancion System consists of 2 catheters used to gain bifemoral arterial access. For CAFA, a flow rate of 1.0 to 1.5 L/min is required, which is provided by inflow and outflow catheters with an external diameter of 12F being inserted into the femoral arteries. Thus, the Cancion System is contraindicated in patients with known severe peripheral vascular diseases. In a canine model of microvascular coronary embolization and cardiomyopathy, CAFA reduced both filling pressure and volumes of the left ventricle and increased left ventricular stroke volume and ejection fraction.7 The mechanism of CAFA action is suggested by data from in vitro and ex vivo arterial models.8 It seems likely from these data that CAFA influences downstream vascular and renal effects by normalizing flow patterns along the aortic endothelial surface that may occur under conditions of reduced cardiac output. A previous study examined 24 patients hospitalized with an exacerbation of HF, inadequately responsive to standard medical therapy, including diuretics and intravenous inotropes and/or vasodilators.6 In this population, administration of CAFA for up to 5 days resulted in a progressive and sustained decrease in pulmonary capillary wedge pressure and an increase in cardiac index. In addition, favorable trends in renal function were observed. A previous publication described complications of the Cancion System in patients with peripheral arterial disease.9 In this case report, we describe the procedure and the results of the implantation of a Cancion System for CAFA in a patient with severe peripheral vascular disease after stenting of the iliac artery, focusing on preparation, insertion of the device, and the patient's clinical and symptomatic response to treatment with the Cancion System. A 71-year-old man was admitted to the hospital for decompensated HF, New York Heart Association (NYHA) class IV. The patient's medical history included coronary artery disease (coronary artery bypass graft surgery in 1996), ischemic cardiomyopathy with severely diminished left ventricular systolic function, and implantation of a St Jude cardioverter-defibrillator in August 2005. The patient had a history of intermittent atrial fibrillation, hypertension, hypercholesterolemia, diabetes mellitus type II, and smoking. On admission to the hospital, the patient complained of dyspnea and was diagnosed with pneumonia and pleural effusion. The patient was severely debilitated, with marked lower extremity edema and abnormal renal function. Transthoracic echocardiography demonstrated severe left ventricular dilation with 20% to 25% ejection fraction and an anterior left ventricular aneurysm. Doppler echocardiography results revealed a mild aortic valve stenosis and severe mitral valve insufficiency. At a recently performed 6-minute walking test, the patient had to discontinue after 2 minutes and 47 m due to severe dyspnea. Implantation of a Cancion System for CAFA was planned in an attempt to improve the patient's hemodynamics and clinical condition. At that time there were no clinical signs of severe peripheral arterial disease. The Cancion system comprises a centrifugal flow pump and electromagnetic motor, a flow sensor, a control system, and 2 percutaneous catheters for the inflow and outflow of blood (Figure 1). The inflow catheter initiates the circuit and leads the blood to the pump. Designed to minimize hemolysis and reduce thrombosis, the sealed bearing-free pump fits on top of the motor. The outflow catheter, with a terminal pigtail configuration, returns blood to the descending thoracic aorta. To maintain smooth operation, the system relies on an advanced control system. The controller features an easy-to-adjust user interface and power supply. The ultrasonic flow sensor measures blood flow without disturbing or contacting the blood itself. After implantation, the blood travels from an iliac artery through the inflow catheter to a small external pump and is returned into the descending aorta. The system superimposes continuous flow on pulsatile aortic flow and never directly connects to the heart. Pump speeds of 3500 to 4500 rpm are used to achieve flow rates of 1.0 to 1.5 L/min. The Cancion System (Orqis Medical Corporation, Lake Forest, CA) is composed of an external bearingless magnetically spun pump (a) and electromagnetic motor (b) combination, a flow sensor (e), a control system (f), and 2 percutaneous catheters for the inflow and outflow of blood. The inflow catheter (d) initiates the circuit and leads the blood to the pump. The pigtail-shaped outflow catheter (c) returns blood to the vascular system. The insertion procedure was performed in the cardiac catheterization laboratory. Standard Seldinger technique was used to gain bifemoral arterial access. Difficulty was encountered during attempts to advance the guidewire through the left femoral artery. The right femoral artery was accessed with a 6F right Judkins catheter, which was positioned at the bifurcation of the aorta. A high-grade stenosis (>80% lumen reduction) of the left femoral artery and further stenosis of the proximal part of the iliac artery (Figure 2) was detected by antegrade infusion of contrast through the Judkins catheter. Therefore, we decided to implant a stent (dynamic noncoated, 9 mm diameter×25 mm length) into the left femoral artery (Figure 3). The stent was implanted by single stop technique and an infusion pressure of 12 atm. On completion of this procedure, we were able to introduce the Cancion inflow catheter into the left femoral artery (Figure 4). By antegrade infusion of contrast through the Judkins catheter from the contralateral side, a high-grade stenosis of the left femoral artery and a further stenosis of the proximal part of the iliac artery were detected (arrows). Arterial stenoses in this area have been described as a relative contraindication for the implantation of the Cancion System (Orqis Medical Corporation, Lake Forest, CA) to perform continuous aortic flow augmentation (CAFA) and a risk factor for limb ischemia or a sudden stop of CAFA blood flow. Implantation of a dynamic noncoated stent (arrow) into the left femoral artery with great angiographic result, giving the opportunity for the implantation of further catheters. Stenting a higher stenosis of the femoral artery enables introducing the inflow catheter (12 F). The inflow catheter reached a persisting flow of >1.2 L/min with 3700 rpm of the vortex pump over a period of 4 days. The small panel in the left lower corner demonstrates the positioning of the tip of the outflow catheter. Arrows indicate the position of the inflow catheter in the previously stented vessel. Following implantation, treatment was carried out in the intensive care unit. In our patient, the flow was stable at 4300 rpm and 1.2 L/min after insertion. After a few hours, the flow had increased to 1.6 L/min at which time we decided to decrease the revolutions per minute to 3800, resulting in a stable flow of 1.45 L/min throughout the remaining treatment time of 4 days. For the duration of treatment, anticoagulation was achieved with continuous infusion of unfractionated heparin to attain partial thromboplastin times of 65 to 85 seconds. Careful fluid management aiming to maintain preload and inflow to the pump as well as to avoid dehydration was undertaken throughout the treatment period since therapy induced a potent diuresis. Uneventful manual catheter removal was performed 4 days postintroduction. We modified the removal procedure by deciding not to exchange the sheath for the outflow catheter but left approximately 7 cm of the outflow catheter inside the sheath. By doing so, we avoided oozing from the sheath valve and maintained sterility. Once we had removed the inflow catheter and achieved hemostasis by using manual compression, we removed the remainder of the pigtail outflow catheter and applied manual pressure to achieve hemostasis. The patient was transferred out of intensive care 1 day after CAFA had been stopped and the Cancion System removed. No postinterventional complications occurred. The patient's clinical condition improved during CAFA, and he remained stable and compensated during the rest of his hospitalization. In addition to his improved clinical condition from NYHA III/IV to NYHA II HF class, we also recorded an improvement in his laboratory and hemodynamic parameters. Specifically, B-type natriuretic peptide levels decreased during CAFA from 2420 to 900 pg/mL at day 4. However, B-type natriuretic peptide values increased after cessation of CAFA. Furthermore, renal function improved, with a reduction of creatinine (1.57–1.37 mg/dL) and an increase in glomerular filtration rate (47–62 mL/min). The Cancion System is intended for hemodynamic improvement and sustained clinical benefit in patients with an exacerbation of chronic HF with renal impairment and/or high diuretic requirement, inadequately responsive to intravenous inotropic and/or vasodilator treatment. The system may be considered only in patients with truly refractory HF. Use of the Cancion System is contraindicated in patients with symptomatic hypotension and in patients with severe peripheral vascular or aorto iliac disease. A previous publication by Saberin and coworkers9 described the application of the Cancion System in a patient with peripheral vascular disease including a 50% stenosis of the left iliac artery. In that case, however, the flow rates dropped from 1.47 to 0.2 L/min, possibly due to obstruction around the inflow cannula near the site of the iliac artery stenosis. The flow reduction occurred 5 hours after initiating therapy. The flow was stabilized by adequate fluid infusion and successfully restored by slightly withdrawing the tip of the inflow catheter. Based on this finding, the authors suggested that peripheral vascular disease is a relative but not an absolute contraindication for CAFA, although patients with evidence of peripheral vascular disease require careful flow monitoring during CAFA therapy. Based on the present findings, we have evidence that, under some circumstances of focal arterial obstruction, CAFA therapy can be safely and efficiently performed. The risk of sudden reduction of flow due to arterial obstruction could be reduced by dilatation of the stenoses before implantation of the inflow catheter. Furthermore, this procedure might reduce the risk of limb ischemia that could occur as a result of CAFA in patients with peripheral arterial disease. CAFA provides a progressive reduction in pulmonary capillary wedge pressure and an increase in cardiac index, consistent with a favorable shift in the Starling curve. The fact that hemodynamic improvement tends to be sustained for at least 24 hours following discontinuation of CAFA treatment supports the view that this therapy "breaks a vicious cycle" in which aortic flow reduction leads to progressive vasoconstriction, which further worsens cardiac output and reduces aortic flow. The progressive decrease in systemic vascular resistance seen with CAFA treatment, as well as renal benefits observed both in animal models7 and in humans,6 suggests that signals initiated through reduced aortic flow, possibly of endothelial origin, drive adverse downstream vascular and renal effects. Based on hemodynamic effects observed with CAFA to date, patients hospitalized with HF exacerbation that is inadequately responsive to medical therapy may benefit from a several-day course of therapy, with improvement in hemodynamics and clinical status. Preclinical work with CAFA using longer duration times of more than 4 days has demonstrated a sustained myocardial benefit10 and might offer a new therapeutic option for patients with severe chronic HF. This case demonstrates that under some circumstances, the Cancion System may be employed in patients with high-grade stenoses of iliac-femoral arteries after vascular stenting, providing clinical benefit over and above that of standard medical treatment. CAFA represents a promising new treatment for patients with exacerbations of chronic HF refractory to conventional medical therapy.