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a Department of Cardiothoracic Surgery, Monash Medical Centre, Clayton, Victoria, Australia
b Department of Cardiology, Monash Medical Centre, Clayton, Victoria, Australia
c Green Lane Cardiothoracic Surgery Unit, Auckland City Hospital, Auckland, New Zealand
Accepted for publication December 14, 2007.
* Address correspondence to Dr Mitnovetski, Cardiothoracic Surgery, Monash Medical Centre, 246 Clayton Road, Clayton, Victoria, 3168, Australia (Email: smitnovetski{at}hotmail.com).
| Drs Peters and Milsom disclose that they have a financial relationship with Sunshine Heart, Inc.
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Abstract |
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Approximately 5,000,000 Americans [1] and 300,000 Australians [2] suffer from chronic heart failure. An estimated 30,000 to 100,000 patients in the United States with advanced disease would benefit from transplantation [3]. Owing to the critical shortage of donor organs for transplantation, new and effective management strategies are required to manage this problem.
We describe the use of an extra-aortic implantable counterpulsation pump (C-Pulse; Sunshine Heart Inc, Tustin, CA) in the long-term management of chronic heart failure. This is a non-blood contacting device that avoids some of the complications of current devices.
The device was implanted through a median sternotomy. The ascending aorta was circumferentially mobilized from the sinotubular junction to the origin of the brachiocephalic artery. The C-Pulse cuff (Sunshine Heart Inc) was placed around the ascending aorta and was secured with interrupted non-absorbable sutures. A bipolar epicardial electrocardiography sense lead was attached to the right ventricular outflow tract (Fig 1). The sense lead and gas lines were tunneled subcutaneously to a pre-determined exit site over the abdomen, and subsequently a patient connector was fitted to these lines. The connector was stabilized by use of strapping adhered to the skin patches. The connector was able to be coupled into either a wearable battery-powered driver or a portable line-powered driver. The drivers were programmable to provide 1:1 counterpulsation. The per-beat blood volume displacement caused by the cuff was approximately 20 cc to 30 cc, depending on the cuff size used (eg, small, medium, or large). The cuffs were designed to fit the ascending aortas of 28 mm to 40 mm in diameter and a minimum ascending aorta length of 70 mm, as determined by a preoperative computed tomographic scan.
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A 73-year-old man presented with heart failure after a large anteroseptal myocardial infarct. During the last 2 years he had multiple admissions with acute pulmonary edema. Despite maximal medical therapy, he remained in New York Heart Association class IV. Other major comorbidities included long-standing, insulin-dependent diabetes mellitus, diabetic nephropathy, and cardiac cachexia.
Coronary angiography revealed severe double-vessel disease. A Sestamibi study showed extensive infarction in the anterior and anteroseptal walls and apex with no viability. This ruled out revascularization. Transthoracic echocardiography demonstrated an ejection fraction of 25%, moderately severe mitral regurgitation, a moderately dilated right heart, and severe pulmonary hypertension (68 mm Hg). Computerized tomographic angiography revealed a thoracic aorta of normal caliber with minimal calcification. Due to his symptoms and advanced heart failure, the patient was referred for implantation of the extra-aortic counterpulsation device to provide relief from symptoms and improve cardiac hemodynamics.
After approval from the Southern Health Human Research Ethics Committee, the C-pulse implantable counterpulsation pump was implanted. A reduction in systolic pulmonary artery pressure from 70 mm Hg to 57 mm Hg, central venous pressure from 20 mm Hg to 13 mm Hg, and the degree of mitral valve regurgitation were immediately observed after the commencement of counterpulsation. Cardiac output increased from 2.3 L/min to 3.9 L/min with the device switched on.
The intensive care stay was uneventful. The patient was extubated on postoperative day 1 and transferred to the ward on postoperative day 4. After a period of adjustment to the C-pulse device and rehabilitation, the patient was discharged home on postoperative day 81. The patient was readmitted to hospital on postoperative day 121 due to dehydration and acute-on-chronic renal failure, with a serum creatinine of 660 mmol/L. His diuretic dose was reduced and he was subsequently discharged again on postoperative day 129 with serum creatinine resolved to pre-implant range (147 mmol/L).
As evidenced by New York Heart Association classification, echocardiography and right heart catheter assessment by his cardiologist, he enjoyed an improved quality of life, hospital-free environment, and valuable time with his family. The requirement of diuretics and other medications significantly decreased, and his New York Heart Association functional class changed from IV to III at 6 months. Right heart catheterization showed an increase in cardiac output from 2.3 L/min preoperatively to 3.1 L/min at 1 month, 3.9 L/min at 3 months, and 3.56 L/min at 6 months with counterpulsation. Echocardiography demonstrated a decrease of mitral regurgitation from moderately severe (grade 3/4) preoperatively to moderate, and reduction of the systolic pulmonary artery pressure from 70 mm Hg to 28 mm Hg at 6 months. The device was able to be disconnected for short periods of time to allow for showering, battery change, and so forth.
Six months and 21 days after implantation of the device, the patient was admitted with localized pain and purulent discharge from the gas line exit site. He felt generally unwell but was afebrile and had a normal white blood cell count on admission. The exit site had been noted to have a small amount of discharge for the past several weeks, but earlier culture had been negative. Fluid cultured from the exit site at admission identified infection with pseudomonas. A thoracic computerized tomographic scan with contrast showed a localized collection around the cuff (Fig 2), but no extravasation of blood was noted after injection of contrast agent. A gallium scan confirmed infection in the anterior abdominal wall in the region of the exit site, but there was no evidence of intrathoracic infection. Aggressive intravenous antibiotic therapy was initiated. The patient developed acute-on-chronic renal failure and low cardiac output syndrome. He was transferred to the intensive care unit and an intravenous inotropic agent was started. The family decided against further therapy and the patient died 5 days after admission. Autopsy confirmed pseudomonas infection associated with the exit site and subcutaneous gas line flocking. There was a small para-aortic abscess associated with the cuff, although no organisms were grown. The corresponding aortic wall demonstrated localized acute inflammatory changes. The aortic intima was intact. The Data and Safety Monitoring Board concluded that the cause of death was multiorgan failure associated with sepsis and that chronic exit site infection with pseudomonas was the likely source of acute involvement of the same organism involving the cuff.
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Comment |
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The Sunshine Heart C-Pulse implantable counterpulsation pump has been designed to provide non-blood contacting, nonobligatory counterpulsation in patients with moderate to severe heart failure. It is an easily implantable device that is wrapped around the ascending aorta and pneumatically driven by an external console. Advantages include no blood contact, thereby reducing the risk of embolism or hemorrhage; ease of implantation with the potential of using minimally invasive surgical techniques; and allowing the patient to ambulate. Diastolic counterpulsation is more effective at the level of the ascending aorta than at the descending aorta [8]. The principal effects of extra-aortic balloon pump are aortic root blood flow augmentation during inflation of the balloon with increase in coronary blood flow (ventricular diastole) and ventricular unloading during the deflation phase (just before ventricular systole) (Fig 3).
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These effects were experimentally confirmed in a pig model in both 1:1 and 1:2 counterpulsation modes [9]. The circulatory effect was comparable if not superior to the intra-aortic device. This study demonstrated the safety of extra-aortic balloon pump in terms of its effect on the aortic wall. Histologic examination of the ascending aorta of the pig showed only mild hemorrhagic inflammatory changes of the adventitia and normal media and intima.
Short-term human studies showed significant increase in diastolic coronary blood flow and reduction in left ventricular afterload [10]. There was a reduction in end-systolic and end-diastolic areas and reduction in ventricular wall stress. There was no increase in the number of high-intensity signals measured by transcutaneous carotid Doppler ultrasound and no neurologic complications in this study.
Extra-aortic counterpulsation does have some limitations. It is contraindicated in patients with ascending aortic atherosclerotic disease, aortocoronary bypass grafts, or aortic regurgitation. The long-term effect of extra-aortic counterpulsation on the human aortic wall is not established. The degree of improvement in cardiac output may be insufficient in patients with New York Heart Association class IV heart failure. As was evidenced by this case, devices with a percutaneous drive line may cause serious infection.
We report a positive clinical experience of using an extra-aortic counterpulsation device in a patient with refractory chronic heart failure. Its further role either as a destination therapy device, bridge to transplantation, or recovery will be determined in future studies.
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