Desiree Robson

First permanent implant of the Jarvik 2000 Heart

BACKGROUND Heart failure is a major public-health concern. Quality and duration of life on maximum medical therapy are poor. The availability of donor hearts is severely limited, therefore an alternative approach is necessary. We have explored the use of a new type of left-ventricular assist device intended as a long-term solution to end-stage heart failure. METHODS As part of a prospective clinical trial, we implanted the first permanent Jarvik 2000 Heart--an intraventricular device with an innovative power delivery system--into a 61-year-old man (New York Heart Association functional class IV) with dilated cardiomyopathy. We assessed the effect of this left-ventricular assist device on both native heart function and the symptoms and systemic characteristics of heart failure. FINDINGS The Jarvik 2000 Heart sustained the patients circulation, and was practical and user-friendly. After 6 weeks, exercise tolerance, myocardial function, and end-organ function improved. Symptoms of heart failure have resolved, and continuous decreased pulse-pressure perfusion has had no adverse effects in the short term. There has been no significant haemolysis and no device-related complications. The skull-mounted pedestal is unobtrusive and has healed well. CONCLUSIONS The initial success of this procedure raises the possibility of a new treatment for end-stage heart failure. In the longer term, its role will be determined by mechanical reliability.

End-organ function during chronic nonpulsatile circulation

BACKGROUND Evolving blood pump technology has produced user-friendly continuous flow left ventricular assist devices, but uncertainty exists about the safety of chronic nonpulsatile circulation. We established consistently nonpulsatile blood flow in a sheep model using the Terumo magnetically suspended centrifugal pump. We then compared end-organ function between pulseless and control animals. METHODS Fifteen healthy sheep (65 to 85 kg) were allocated to either left ventricular assist device (n = 9) or control (n = 6) groups. We implanted the device through a left thoracotomy and determined the flow rate at which pulse pressure was absent. The flow rate was then adjusted to exceed that rate (4.2 +/- 1.5 L/min), and all variables of pump function were continuously monitored by computer. Blood tests were taken serially for hepatic and renal function and plasma renin levels. The sheep were sacrificed electively at 30 (n = 3), 90 (n = 4), 180 (n = 1), and 340 (n = 1) days. Detailed histologic examination was made of the brain, liver, kidney, myocardium, and major arteries. RESULTS All animals remained in good condition until sacrifice. All measures of end-organ function remained within normal limits for both groups. There were no histologic differences between the organs of pulsatile and nonpulsatile animals. Although there was no significant difference in mean blood pressure, plasma renin levels were substantially elevated in pulseless animals (1.4 +/- 0.3 pg/mL versus 2.9 +/- 0.3 pg/mL; p < 0.05). We also identified thinning of the medial layer of the ascending aorta in nonpulsatile sheep (1.8 +/- 0.4 mm in left ventricular assist device animals versus 2.6 +/- 0.6 mm in control sheep; p < 0.05). CONCLUSIONS Chronic nonpulsatile circulation was well tolerated, and we found neither functional nor histologic changes in major end organs. The renin-angiotensin system was upregulated, but this did not provide a significant rise in blood pressure. The changes in the aortic wall merit further investigation. As a result of these findings, we consider that nonpulsatile devices can be used safely for long-term circulatory support.

Does furosemide prevent renal dysfunction in high-risk cardiac surgical patients? Results of a double-blinded prospective randomised trial §,§§

OBJECTIVE Renal dysfunction following cardiac surgery is more apparent in high-risk patients with pre-existing renal dysfunction, diabetes and impaired left-ventricular function, and following complicated procedures involving prolonged cardiopulmonary bypass (CPB). The aim of this prospectively randomised double-blinded placebo-controlled study was to evaluate reno-protective effect of low-dose furosemide infusion in this high-risk group. METHODS Patients with preoperative serum creatinine >130 micromol/l (1.4 mg/dl), left-ventricular ejection fraction <50%, congestive heart failure, diabetes, or procedures involving prolonged CPB were randomised to receive either saline at 2 ml/h (n=21), or furosemide at 4 mg/h (n=21). Infusion was commenced after induction of anaesthesia and continued for 12h postoperatively. Renal dysfunction was defined as >50% increase in serum creatinine postoperatively, or >130 micromol/l (1.4 mg/dl), or requirement for haemodialysis, or all of these. In patients with preoperative serum creatinine >130 micromol/l, >50% increase over preoperative levels was used to define postoperative renal dysfunction. RESULTS Following cardiac surgery, patients receiving furosemide had a higher urine output (3.4+/-1.2 ml/kg/h in furosemide group and 1.2+/-0.5 ml/kg/h in placebo group; p<0.001), higher postoperative fluid requirement (4631+/-1359 ml in furosemide group and 3714+/-807 ml in placebo group, p=0.011), and lower urinary-creatinine (2+/-1.3 micromol/l in furosemide group and 5.9+/-2.5 micromol/l in placebo group p<0.001). Both groups had significant increase in retinol binding protein/creatinine ratio (7.2+/-6 to 3152+/-1411 in furosemide group; 4.9+/-2.1 to 2809+/-1125 in placebo group; p<0.001) and peak serum creatinine (98+/-33 to 177+/-123 micromol/l in furosemide group; 96+/-20 to 143+/-87 micromol/l in placebo group; p<0.001), and a significant decrease in peak creatinine-clearance (64.3+/-29.4 to 39.1+/-16.6 ml/min in furosemide group; 65.5+/-38.6 to 41.8+/-17.8 ml/min in placebo group; p<0.001) following cardiac surgery, implying significant renal injury following cardiac surgery. Peak creatinine levels (177+/-123 micromol/l in furosemide group and 143+/-87 micromol/l in placebo group; p=0.35) and peak creatinine-clearance (39.1+/-16.6 ml/min in furosemide group and 41.8+/-17.8 ml/min in placebo group; p=0.61) were similar in the two groups. Importantly, there was no difference in incidence of renal dysfunction between the furosemide group (9/21) and the control group (8/21) (relative risk 1.1, 95% confidence interval 0.6-2.2; p=0.99). CONCLUSIONS Our randomised trial did not demonstrate any benefit of furosemide-infusion postoperatively in high-risk cardiac surgical patients. Although urinary output increased with furosemide, there was no decrease in renal injury, and no decrease in incidence of renal dysfunction.

Circulatory Support for Long-Term Treatment of Heart Failure Experience With an Intraventricular Continuous Flow Pump

Background—A lifetime mechanical solution for advanced heart failure must be reliable, with a low risk of life-threatening complications. After extensive laboratory testing, we began clinical trials with an axial flow pump for long-term treatment of New York Heart Association class IV, transplant-ineligible patients. Methods and Results—The Jarvik 2000 is a continuous flow device that is implanted in the apex of the left ventricle with offloading to the descending thoracic aorta. Skull-based percutaneous power delivery was derived from cochlear implant technology. We used this system in 4 patients with end-stage dilated cardiomyopathy. Exercise capacity, quality of life, device parameters, and native heart function were monitored serially. One patient died from right heart failure at 3 months. The other patients were discharged from hospital between 3 and 8 weeks postoperatively and are currently New York Heart Association I or II. Follow-up lasted between 9 and 20 months. There has been no device failure or hemolysis. Native heart function and quality of life were markedly improved. Conclusions—The Jarvik 2000 is a true assist (rather than replacement) device that functions synergistically with the native left ventricle and provides excellent quality of life. Adverse events are infrequent. This blood pump may provide a mechanical solution for end-stage heart failure in the community.

High-pressure suction drainage via a polyurethane foam in the management of poststernotomy mediastinitis

BACKGROUND This study was performed to evaluate the effectiveness of suction drainage in the management of early poststernotomy mediastinitis. METHODS From September 1998 to August 1999, we encountered nine cases of poststernotomy mediastinitis out of 1,209 adult median sternotomies performed in this time period. All these cases were treated with suction drainage, which was recently introduced to our management protocol. From September 1997 to August 1998, we encountered 11 cases of poststernotomy mediastinitis of 1,343 adult median sternotomies. All these cases were initially treated by closed drainage and irrigation, which was our previous first-line management. We used the latter group as historical controls for the evaluation of suction drainage. Lengths of hospitalization were compared using the Mann-Whitney U test, and success versus failure of the primary treatment was compared using the chi2 test. RESULTS Treatment with the suction dressing resulted in a decreased length of hospitalization after treatment starts (p = 0.02) and a lower rate of treatment failure (p = 0.03). CONCLUSIONS The use of high-pressure suction drainage is a valuable adjunct in the early management of poststernotomy mediastinitis.

Reliable long-term non-pulsatile circulatory support without anticoagulation

OBJECTIVE The Terumo implantable left ventricular assist system (T-ILVAS) consists of a titanium centrifugal pump with a unique magnetically suspended impeller producing continuous (non-pulsatile) flow up to 10 l/min. The interior surface is heparin-coated and there is no purge system. We implanted the device into six sheep to ascertain in-vivo haemodynamic function, mechanical reliability and biocompatibility. METHODS The T-ILVAS was implanted via left thoracotomy without cardiopulmonary bypass. The inflow cannula was placed in the left ventricular apex and a Dacron outflow graft anastomosed to the descending aorta. All animals recovered well. No anticoagulation (heparin or warfarin) was given after the surgery. Suspension position, motor current, impeller speed and pump flow were continuously monitored and stored by on-line computer. Serial blood samples were collected to determine haematological and biochemical indices of renal function, liver function and haemolysis. All animals were electively euthanized between 3 and 7 months postoperatively. The explanted pumps were examined for mechanical reliability and thrombus formation. Major organs were examined macroscopically and histologically for thromboembolism. RESULTS All animals appeared completely normal for up to 210 days. At speeds between 1500 and 2000 rev./min the device pumped up to 8 l/min capturing all mitral flow. There were no major complications (pump failure, thromboembolism, haemorrhage, or driveline infection). Indices of haemolysis, liver and renal function remained within normal limits. All pumps were mechanically sound and free from thrombus. One embolus was found in a sectioned kidney. CONCLUSION The T-ILVAS successfully supported the systemic circulation without anticoagulation for up to 210 days. Mechanical reliability and biocompatibility were demonstrated. Organ function remained within normal limits during continuous non-pulsatile flow.