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Ann Thorac Surg 1999;68:870-873
© 1999 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Bileaflet mechanical valve (St. Jude Medical valve) replacement in long-term dialysis patients

^a Department of Cardiovascular Surgery, Kumamoto City Japan
^b Departmetn of Nephrology, Kumamoto Central Hospital, Kumamoto City, Japan

Address reprint requests to Dr Sakata, Kumamoto Central Hospital, 96 Tainoshima, Tamukae-machi, Kumamoto City, 862 Japan
e-mail: masashik{at}orange.ocn.ne.jp

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Few reports exist on the results of bileaflet mechanical valve (St. Jude Medical prosthesis; St. Jude Medical, Inc, St. Paul, MN) replacement in long-term dialysis patients.

Methods and Results. We retrospectively reviewed 12 patients, ranging in age from 50 to 86, undergoing long-term renal dialysis who had also undergone mechanical valve replacement at our institution. Operative procedures included aortic valve replacement, aortic and mitral valve replacement, aortic valve replacement and mitral annuloplasty, mitral valve replacement, and modified Bentall’s operation. There was 1 hospital death (8.3%). During the mean follow-up period of 37.1 months (range: 5–87 months), there were 2 noncardiac late deaths. Bleeding from the esophageal varix and from a duodenal ulcer occurred in 1 patient with end-stage liver cirrhosis. There were no other major cases of bleeding or cerebrovascular accidents. There were no valve-related complications. All the survivors demonstrated excellent clinical improvement under the NYHA functional classification.

Conclusions. Our study demonstrated good early and long-term results of mechanical valve replacement in patients undergoing long-term dialysis. These favorable results support the continued use of mechanical valves in dialysis patients.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
With the improvement of operative techniques and perioperative management, favorable results of cardiac operations have been reported for patients undergoing long-term renal dialysis, especially in coronary artery bypass grafting [1–4].

In contrast, since the first report of valvular operation in 1968 [5], the number of valvular operations has been relatively small. Because of premature calcification in biological valves, mechanical valves have been commonly indicated in long-term renal dialysis patients requiring valve replacement [6–7]. This view has recently been challenged in a report by Lucke and associates [8]. Although they conclude that the use of mechanical valve is associated with significant risk of complications, and that preference should be given to biological valve instead of mechanical valve prostheses in patients on long-term renal dialysis, little is known about the results of bileaflet mechanical valve (St. Jude Medical prosthesis; St. Jude Medical, Inc, St. Paul, MN) replacement.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Twelve patients with chronic renal failure who underwent mechanical valve replacement at Kumamoto central hospital between April 1988 and March 1998 were re-viewed. This represents 1.8% of 662 patients in total who underwent valve surgery during the same interval. The patients consisted of 6 men and 6 women with a mean age of 60.1 (range: 50–86). Preoperative characteristics are summarized in Table 1. Hemodynamic instability (hypotension or cardiac symptoms) during dialysis was noted in 4 patients.

Maintenance dialysis was resumed the day after the operation. Nafamostat mesilate instead of heparin was selected as the anticoagulant agent for the first postoperative HD.

Operative procedures
All the operations were performed using standard CPB with moderate hypothermia (30°C–32°C). All the valves were St. Jude Medical valves. Operative procedures are summarized in Table 2. Concomitant procedures included coronary artery bypass grafting in 3, LV aneurysmectomy in 1, and De Vega’s tricuspid annuloplasty in 1. Postoperative oral anticoagulation therapy was started in most cases on the second or third postoperative day. Weattempted to anticoagulate patients with warfarin sodium, with the thrombotest maintained between 10% and 25%. An antiplatelet regimen of dipyridamole (200 mg daily) and aspirin (81 mg daily) was added to warfarin.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Operative results
One operative death (8.3%) occurred. A 68-year-old man (case 5) who was doing well after a double valve replacement and TAP died 29 days after the operation of sepsis and subsequent multiple organ failure following ordinary maintenance dialysis. All the patients were extubated within 48 hours, with a mean intubation time of 20.0 ± 8.3 hours. Postoperative complications are summarized in Table 3.

There were 2 late deaths among the operative survivors during the mean follow-up of 37.1 months (range: 5–87 months). One patient (case 3) died of liver cirrhosis 65 months after the operation and another (case 6) died of gastric cancer 24 months after the operation (Table 4).

Withdrawal of anticoagulant
Withdrawal of anticoagulant was required in 2 patients during the follow-up period. In case 3, a patient with end-stage liver cirrhosis who had recurrent bleeding from the esophageal varix and a duodenal ulcer, anticoagulant was stopped for 2.5 years. Lack of use of anticoagulant did not lead to thromboembolic events; however, the patient suffered from recurrent bleeding and eventually died of liver cirrhosis as mentioned above. In another patient (case 9), stopping of anticoagulant was necessary before elective operation for arteriosclerosis obliterans (ASO); this did not lead to complications.

Valve-related complications
There were no valve-related complications such as thromboembolic events, prosthetic endocarditis, hemolysis, structural deterioration, or nonstructural dysfunction during the follow-up period.

Clinical improvement
All the survivors demonstrated excellent clinical improvement according to the NYHA functional classification. Five were in class IV, 5 in class III, and 1 in class II preoperatively, whereas 6 were in class I, 4 in class II, and 1 in class III postoperatively. Every patient demonstrated improved NYHA functional status.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Because there have been a number of reports about premature calcification in biological valves in long-term renal dialysis patients [6–7], mechanical valves have usually been indicated in these patients requiring valve replacement [1–4].

This view has been recently challenged in a report by Lucke and associates [8]. The overall estimated Kaplan-Meier survival was 60% ± 12% at 12 months and 42% ± 14% at 60 months. A large number of patients died during the first 12 months after the operation. They noted that mechanical valve patients had a significantly higher rate of postoperative cerebrovascular accidents or bleeding complications (10 of 10 versus 0 of 9; ² = 17.0; p < 0.001). They concluded that the use of mechanical valves was associated with significant risk of complications and that preference should be given to biological valves instead of mechanical valve prostheses in patients on long-term renal dialysis. However, this conclusion should be interpreted with caution.

First, there were significantly more aortic and fewer mitral valve replacements in patients undergoing biological valve replacement. Eight of 9 biological valves were aortic, whereas only 4 of 10 mechanical valves were aortic. Thromboembolic complications were significantly higher in patients with mitral valve replacements when compared to patients with aortic valve replacements. Mitral valve prostheses tend to require a more intensive anticoagulation regimen [9–10], which may partially explain the higher rate of postoperative cerebrovascular accidents or bleeding complications in the mechanical valve patient group in Lucke and associates’ study.

Second, as pointed out in their invited commentary, the type of mechanical valves was not uniform in their study. We have used St. Jude Medical valves exclusively in renal dialysis patients. Although the excellent performance of the St. Jude medical valve has been demonstrated in various studies [9–12], little is known about the results of bileaflet mechanical valve replacement in long-term renal dialysis patients.

Lucke and associates noted that bleeding complications occurred to a significant degree in patients with mechanical valves. Bleeding at the site of the arteriovenous fistula or polytetrafluoroethylene graft occurred in 4 of 7 mechanical valve patients on hemodialysis, and they often required dialysis through an indwelling venous catheter [8].

In our experience, no such procedures were required. Although our series included 1 minor case of bleeding from the CAPD tube exit site, careful management of the anticoagulant regimen easily prevented aggravation of symptoms. Relatively longer cessation of warfarin regimen was required in only 1 terminally ill patient with liver cirrhosis. Lower intensity anticoagulation therapy has recently been demonstrated to result in lower complication rates with the St. Jude Medical prosthesis [9–12]. Japanese patients with mechanical valve replacements tend to be kept under a lower-level warfarin treatment regimen than in the United States [13]. We attempted to anticoagulate patients with warfarin sodium, with the thrombotest maintained between 10% and 25%. Although accurate control range data based on the prothrombin time international normalized ratio (PT-INR) was not available for our series, the control range for warfarin based on the PT-INR seems to be higher in most series from the United States than that noted in this series. This might explain our more successful late results.

Frequent percutaneous puncture of their arteriovenous fistula for dialysis puts dialysis patients at additional risk of infection. In fact, 1 of our patients died of sepsis and subsequent multiple organ failure following ordinary maintenance dialysis. Conversion from hemodialysis to peritoneal dialysis might be beneficial for reducing the risk of infection, especially prosthetic valve endocarditis, although no definite conclusion can be drawn from such a small number of patients.

Our study demonstrated the successful performance of the St. Jude medical valve in long-term renal dialysis patients. No patients experienced structural deterioration or nonstructural dysfunction during the follow-up period. The well known long-term durability of the St. Jude Medical valve [9–13] could help high-risk renal dialysis patients to avoid the additional risk of reoperation as a result of structural deterioration of biological valves.

It was noteworthy that, in contrast to previous reports, 9 of the 11 operative survivors lived longer than 2 years, and 4 patients survived longer than 4 years. During a mean follow-up of 37.1 months (maximum 87 months), only 2 patients died from noncardiac causes. Longer survival can be expected as a result of the high performance of bileaflet mechanical valves and improved management of dialysis patients.

Our study demonstrated good early and long-term results after mechanical valve replacement in patients undergoing long-term dialysis. Although this study did not demonstrate the superiority of performance of bileaflet mechanical valves over biological valves in dialysis patients, our favorable results support continued use of mechanical valves in dialysis patients. This procedure should not be renounced unless the superiority of biological valves is clearly demonstrated.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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