Smeloff-Cutter Prosthesis: 1- to 12-Year Follow-up David S. Starr, M.D., Gerald M. Lawrie, M.D., J. F. Howell, M.D., and George C. Morris, Jr., M.D.

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1 Clinical Experience with the Smeloff-Cutter Prosthesis: 1- to 12-Year Follow-up David S. Starr, M.D., Gerald M. Lawrie, M.D., J. F. Howell, M.D., and George C. Morris, Jr., M.D. ABSTRACT To determine the long-term results of aortic valve replacement with the Smeloff-Cutter prosthesis, the fate of 358 of 459 (78%) consecutive patients was determined 1 to 12 years postoperatively. There were 319 male patients (70%). Mean age at operation was 57 years (range, 15 to 84 years). Aortic stenosis was the dominant lesion in 267 patients (58%) and aortic regurgitation in 133 patients (29%). Fifty-nine patients (13%) had both aortic stenosis and regurgitation. In addition to aortic valve replacement, 93 patients (20%) had coronary artery bypass, 30 (6.5%) had mitral commissurotomy, 23 (5%) had mitral valve replacement, and 41 (9%) had other procedures. Preoperative status by New York Heart Association Functional Class was: Class I, 3 (l0/o); Class 11, 39 (8%); Class 111, 148 (32%); and Class IV, 269 (59%). Operative (30-day) mortality was 8.5% (39 out of 459). Functional improvement was obtained in all postoperative survivors: 345 (82%), Class I; 63 (15%), Class 11; and 12 (3?40), Class 111. A penvalvular leak developed in 6 patients (1%) and subacute bacterial endocarditis in five (l?'~). Actuarial longterm survival was 80% at 5 years and 71% at 8 years. Thromboembolism occurred in 34 patients (9.5%). The incidence of thromboembolism per 100 patientyears for patients receiving no anticoagulants was 5.4; antiplatelet agents, 2.9; and Coumadin (sodium warfarin), 2.6. Major thromboembolism was uncommon in patients on a regimen of sodium warfarin but major morbidity from bleeding was signif icant. The Smeloff-Cutter prosthesis, introduced in 1964, has been used without further modification in either material or design since Sep- From the Cora and Webb Mading Department of Surgery, Baylor College of Medicine, Houston, TX. Presented at the Sixteenth Annual Meeting of The Society of Thoracic Surgeons, Jan 21-23, 1980, Atlanta, GA. Address reprint requests to Dr. Starr, 1393 Mt Everett Rd, Hubbard, OH tember, 1966 [l]. The literature available assessing the long-term results of this prosthesis is scanty compared with that for the Starr- Edwards prosthesis. However, previous reports [l-41 of experience with this valve are encouraging, especially with regard to the low incidence of thromboembolism and the total absence of material failures. This report is based on the experience of two surgeons (G. C. M. and J. F. H.) who performed 459 consecutive aortic valve replacements using the Smeloff- Cutter prosthesis between 1969 and Materials and Methods A retrospective review was made of 459 patients who underwent consecutive aortic valve replacement with a Smeloff-Cutter prosthesis between 1969 and Follow-up was possible in 358 patients (78%) by letters to the patient and referring physician (290 patients), by telephone (53 patients), or direct follow-up in the clinic (15 patients). Of the 459 patients, 319 (70%) were male and 140 (30%) were female. The mean age at operation was 57 years (range, 15 to 84 years). Actuarial survival curves were constructed by standard methods [5]. Operative deaths were omitted; patients dying of any cause were included as cardiac deaths. Patients lost to follow-up were withdrawn at the appropriate time. Aortic valve lesions were designated aortic stenosis or aortic regurgitation or a combination of both according to the criteria described by Hirshfeld and colleagues 161. Aortic stenosis was defined as severe aortic stenosis with 1+ or less aortic regurgitation; aortic regurgitation was defined as severe aortic regurgitation accompanied by a peak systolic left ventricular outflow gradient of less than 25 mm Hg. The lesion was aortic stenosis in 267 patients (58%) and aortic regurgitation in 133 pa by The Society of Thoracic Surgeons

2 449 Starr et al: Smeloff-Cutter Prosthesis Table 1. Preoperative Symptoms Number Of Patients NYHA Class Fig 1. Preoperative and postoperative status by New York Heart Association (NYHA) Class of459 patients undergoing aortic valve replacement with the Smeloff- Cutter pros thesis. Symptoms Congestive heart failure Syncope Angina pectoris Coronary artery disease present Coronary artery disease absent Congestive heart failure and angina Angina and syncope Congestive heart failure and syncope Congestive heart failure, angina, and syncope No. of Patients (N = 459) 217 (47%) 34 (7%) 81 (18%) 26 (6%) 60 (13%) 24 (5%) 8 (2%) 18 (4%) 55 (12%) tients (29'/0). Combined lesions with fixed orifice aortic stenosis and aortic regurgitation were present in 59 patients (13%). The cause of the valvular disease could not be determined in 114 patients (25%). Calcific aortic stenosis accounted for 167 (36%) and rheumatic heart disease, 107 (23%). Annuloectasia with aortic regurgitation and an associated aneurysm of the ascending aorta occurred in 29 patients (6%) and acute or subacute bacterial endocarditis with destruction of the aortic valve and aortic regurgitation, in 12 (3%). Other pathological conditions, including congenital aortic stenosis and thrombosis of a Bjork-Shiley prosthesis, accounted for another 30 patients (6.5 %). The preoperative condition of the 459 patients is shown in Figure l and Table l. Of these, 417 (No/,) were severely symptomatic and were classified in New York Heart Association (NYHA) Functional Class I11 or IV before operation. In the whole preoperative group, 303 patients (66%) were treated for congestive heart failure; 183 (40%) had angina pectoris; and 84 (18%) had episodes of syncope. Of the group with angina pectoris, 63 patients had coronary artery disease demonstrable by arteriography while the other 120 had normal coronary arteries. Thromboembolism was assumed when the clinical episode could have been due to embolism and no other cause was found. Episodes were regarded as major when they resulted in death or permanent disability. Since bleeding from excessive anticoagulation can cause significant morbidity or even mortality, the incidence of this was calculated in the same way as that of thromboembolism. Bleeding was defined as major when it resulted in death or permanent disability, or required blood transfusion. Minor bleeding was bleeding that required hospital admission. Other episodes of bleeding were regarded as sideeffects of Coumadin (sodium warfarin) therapy. Operative Techniques In all patients, valve replacement was performed with median stemotomy and normothermic cardiopulmonary bypass utilizing hemodilution priming and membrane oxygenation. The valve was approached through a transverse aortotomy. The coronary arteries were not perfused, and the operation was done under normothermic ischemic arrest with a mean aortic clamp time of 59 minutes (range, 36 to 93 minutes). Other procedures were combined with aortic valve replacement in 177 patients (39%). Coronary artery bypass using saphenous vein autograft was performed on 93 patients (20%), with an average of 1.1 bypass grafts per patient. Mitral commissurotomy was performed on 30 patients (6.5%) and mitral valve replacement on 23 (5%).

3 ~~ 450 The Annals of Thoracic Surgery Vol 30 No 5 November 1980 The Smeloff-Cutter aortic valve prosthesis was used when the aortic root and annulus would admit a No. 2 (23 mm) size or larger. If the valve annulus or aortic root was smaller than this, a Bjork-Shiley prosthesis was used. The most common size in the series was a No. 3 (198 patients or 43%). The valve was sutured in position with interrupted 2-0 braided Dacron. Results Operative Deaths Thirty-nine (8.5%) of the 459 patients died within 30 days of operation. The cause of 15 operative deaths was pump failure secondary to massive intraoperative infarction. The operative risk was known to be high in 12 of these 15 patients: 10 had triple-vessel coronary artery disease while 2 had refractory congestive cardiac failure. Left ventricular end-diastolic pressure was more than 15 mm Hg in 8 of these patients and was 45 mm Hg in l. Twelve of them were found to have marked left ventricular hypertrophy at postmortem examination. Six patients died of noncardiac causes within 30 days of operation. Three bled profusely from a chronic duodenal ulcer; 1 died of acute-onchronic asthma and 1 of septicemia following valve replacement for acute bacterial endocarditis; and 1 had a fatal cerebrovascular hemorrhage. cum. survival (%I 0 I I I Years Fig 2. Cumulative survival of 358 patients followed for 1 to 14 years after aortic valve replacement with the Smeloff-Cutter prosthesis. (See text.) Late Deaths Sixty-three (15%) of the 420 operative survivors died subsequently of cardiac or unknown causes one month to 12 years after operation. The average mortality for the entire group was 4% per annum. Figure 2 shows the survival curve for the whole group, omitting perioperative deaths, and counting unknown and uncertain causes of death as cardiac in nature. Patient survival at 5 years was 80% and at 10 years, 57%. Thromboembolism Thirty-four patients (9.5%) had episodes suggestive of thromboembolism (Table 2). Twenty- Table 2. Analysis of Thrornboembolism and Anticoagulant Complications in Follow-up Group after Aortic Valve Replacement with Smeloff Valve (N = 358) Emboli Emboli + Embolic Bleeding per 100 Bleeding per Episodes Episodes Patient- Patient- 100 Patient- Anticoagulant (patients) (patients) Years Years Years ALL EPISODES Coumadin 26 Aspirin + 4 dipyridamole None MAJOR EPISODES ONLY Coumadin Aspirin dipyridamole None

4 451 Star et al: Smeloff-Cutter Prosthesis Incidence of.t 6r 4 n I I complications from anticoawlants major minor r-1 I I. - I I I I I ;! I Methods). Significant bleeding occurred in a total of 27 patients, all of whom were on a regimen of Coumadin. The incidence was 2.9 episodes per 100 patient-years. Major bleeding occurred in 21 patients, an incidence of 2.1 episodes per 100 patient-years. 0 L None A-P Anticoagulant status Coumadin Fig 3. Incidence of thromboembolism (TE) according to anticoagulant status in 358 patients followed after aortic valve replacement with the Smeloff-Cutter prosthesis. For those receiving no anticoagulant medication, follow-up included 75 patient-years. For those on a regimen of aspirin and Persantine (dipyridamole) (A-p), follow-up was 137 patient-years. For those on a regimen of Coumadin (sodium warfarin), follow-up was 968 patient-years. Major bleeding complications from anticoagulant (Coumadin) are added to the incidence of thromboembolism in the last group. (See text and Fig 2.) six experienced them while on a regimen of Coumadin; major episodes occurred in 18 patients and a minor episode in 8. Four patients had episodes while on a regimen of aspirin and dipyridamole (Persantine), while 4 patients were receiving no anticoagulants at the time of the embolic event. The frequency of thromboembolism varied according to anticoagulant status (Fig 3; see Table 2). Patients receiving no anticoagulant had the highest frequency of thromboembolism (5.4 per 100 patient-years). Those on a regimen of Coumadin had the lowest frequency (2.6). Major emboli were uncommon in patients receiving Coumadin anticoagulation (1.9 major episodes per 100 patient-years). Patients on a regimen of antiplatelet agents or no medication had a similar, but higher incidence of major thromboembolism (2.2 and 4.0 per 100 patient-years, respectively). Overall incidence of thromboembolism was 2.4 per 100 patientyears. Bleeding from anticoagulant therapy also can have significant morbidity and even mortality. Consequently, the incidence of this was calculated in the same way as that of thromboembolism. These events were also divided into major and minor episodes (see Materials and Improvement in Functional Status Although 91% (417 out of 459) of the patients were in NYHA Class I11 or IV preoperatively, 82% (345 out of 420) of the survivors were in Class I postoperatively, with another 15% (63) in Class 11. Only 3% (12) had minimal improvement from Class IV to Class 111, despite adequate outflow tract and valve size in all these patients (valve sizes ranged from No. 3 to No. 5). Postoperative Morbidity Six patients (l /o) had perivalvular leaks, which were found from three weeks to 2 years after operation (mean, eight months). In 5 patients (1 YO), prosthetic subacute bacterial endocarditis developed from six months to 10 years after operation, secondary to infections elsewhere in the body. Two of these patients died of vegetations obstructing normal prosthesis function. Hemolysis was not a clinically significant problem except in 1 patient who had hemolysis secondary to a perivalvular leak. The hemolysis disappeared after repair of the leak. Reoperation was necessary in 8 patients (1.9%) from two months to 8 years after operation (mean, 5.2 years). Five of these patients had perivalvular leaks, and a second valve replacement was necessary in 2 of them to repair the leak. Another 3 patients required a second valve replacement following subacute bacterial endocarditis involving the prosthesis. There were no instances of prosthetic malfunction in this series. Anticoagulation Of the 155 patients on a regimen of Coumadin anticoagulation at the time of follow-up, 21 had experienced major bleeding complications of anticoagulants involving either permanent blindness (2 patients), or operation or resuscitation by blood transfusion or both (19 patients). Another 6 patients had minor episodes

5 452 The Annals of Thoracic Surgery Vol 30 No 5 November 1980 of bleeding necessitating hospital admission but no operation or transfusion. The 46 patients on a regimen of aspirin and dipyridamole reported no complications from these drugs. Comment The Smeloff-Cutter prosthesis is distinctive in several respects. The second model Smeloff- Cutter prosthesis was introduced in September, 1966, and utilizes a mild cure process for the silicone poppet, which is selected for orifice clearance individually for each valve. These steps have virtually eliminated the problem of ball variance [7], which has not been reported in the present model since its introduction. The valve construction includes one piece of titanium without welds, a double-cage, and a full-flow orifice. Both cages are open, and the poppet is smaller than the valve ring when closed, thus allowing minimal retrograde flow and creating a "washing" effect on the valve surfaces. Long-Term Survival Actuarial methods [5] provide a better basis for comparison between series than the late mortality quoted in some of them. Several recent series allow comparison on the basis of valve type, long-term survival, and the incidence of thromboembolic episodes. Rubin [8], Oyer [9], and their colleagues, and Bonchek and Starr [lo] showed similar improved long-term survival with late model Starr-Edwards prostheses (2310 and 2320) compared with earlier models, achieving 70 to 80% 5-year survival. Operative mortality is omitted from these results. Results with the Bjork-Shiley prosthesis were similar [8] and approximated the 80% 5-year survival in the present series (see Fig 2). The early experience with the Smeloff-Cutter prosthesis of Lee and co-workers [2] and the experience of the Mayo Clinic [lll and New York University [12] using Starr-Edwards prostheses demonstrated significantly lower long-term survival, with a level of 70% 5-year survival. More recently, McHenry and associates [13] reported an improved 5-year survival of 76% with the Smeloff-Cutter prosthesis. Thromboembolism The formation of "white" thrombi, consisting largely of platelets, as occurs in cloth-covered prostheses [lo], can lead to minor thromboembolism. Major episodes, however, are probably caused by fibrin thrombus forming on the preceding platelet thrombus and subsequent embolism of a mixed thrombus of substantial size. The Smeloff-Cutter prosthesis incorporates a design feature to reduce platelet thrombi-minimal retrograde flow during diastole. Also, the antiplatelet agents aspirin and dipyridamole are administered to reduce platelet thrombi. Patients receiving no anticoagulant medication had a relatively low incidence of major thromboembolism in this series (4.0 major episodes per 100 patient-years), while patients on a regimen of antiplatelet agents had a significantly lower incidence (2.2 major episodes per 100 patient-years). Patients on a regimen of warfarin seemed well protected from major thromboembolism (1.9 major episodes per 100 patient-years), but major morbidity among those receiving Coumadin occurred with a significant incidence, giving a total major morbidity of 4.0 episodes per 100 patient-years for this group. Those receiving no medication had a higher incidence of minor embolic events, probably reflecting platelet emboli (total of 5.4 episodes per 100 patient-years). For the recent cloth-covered and track model Starr-Edwards prostheses, the incidence of thromboembolism is reported to range from 0 to 7.2 episodes per 100 patient-years in anticoagulated patients [8, 10, 121 to 29 episodes per 100 patient-years in patients whose anticoagulant regimen had been stopped. In general, tilting-disc prostheses have a higher incidence of thromboembolism than was reported in the present series. The incidence ranges from 0 to 5.0 episodes per 100 patient-years in anticoagulated patients with a Bjork-Shiley prosthesis [8, 141. In addition, thrombosis of the prosthesis with resultant left ventricular outflow tract obstruction remains a problem with the Bjork-Shiley and Lillehei- Kaster disc valves [8, 151. The relatively low incidence of thromboembolism in patients on a regimen of antiplatelet agents only or no medication is a most desirable feature of the Smeloff-Cutter prosthesis, especially in situations of low patient compliance. In summary, the Smeloff-Cutter valve is a

6 453 Starr et al: Smeloff-Cutter Prosthesis mechanically reliable and durable prosthesis with proved excellent long-term survival and markedly low rates of thromboembolism even in unanticoagulated patients or patients on a regimen of antiplatelet agents only. This prosthesis is probably underutilized, especially in those situations when social factors render follow-up and reliable anticoagulation a difficult and uncertain matter. References 1. McHenry MM, Smeloff EA, Matlof HJ, et al: Long-term follow-up of patients with present model Smeloff-Cutter valve (abstract). Circulation 51,52:Suppl 2:215, Lee S, Barr C, Callaghan J, et al: Long-term survival after aortic valve replacement using Smeloff-Cutter prosthesis. Circulation 52:1132, Brawley R, Donahoo J, Gott VL: Current status of the Beall, Bjbrk-Shiley, Braunwald-Cutter, Lillehei-Caster and Smeloff-Cutter cardiac valve prosthesis. Am J Cardiol 35:855, Sarma R, Roschke E, Harrison E, et al: Clinical experience with the Smeloff-Cutter aortic valve prosthesis: an 8-year follow-up study. Am J Cardiol 40:338, Anderson RP, Bonchek LI, Grunkemeier GL, et al: The analysis and presentation of surgical results by actuarial methods. J Surg Res 16:224, Hirshfeld J, Epstein S, Roberts A, et al: Indices predicting long-term survival after valve replacement in patients with aortic regurgitation and patients with aortic stenosis. Circulation 50:1190, McHenry MM, Smeloff EA, Fong WY, et al: Critical obstruction of prosthetic heart valves due to lipid absorption by Silastic. J Thorac Cardiovasc Surg 59:413, Rubin JW, Moore HV, Hillson RF, Ellison RG: Thirteen year experience with aortic valve replacement. Am J Cardiol 40:345, Oyer PE, Stinson EB, Randall BG, Shumway NE: Valve replacement with the Starr-Edwards and Hancock prostheses. Ann Surg 186:301, Bonchek LE, Starr A: Ball valve prostheses: current appraisal of late results. Am J Cardiol35:843, Duvoisin GE, McGoon DC: Aortic valve replacement with a ball valve prosthesis: detailed analysis of early and late results. Arch Surg 99:684, Isom OW, Spencer FC, Glassman E, et al: Long-term results in 1,375 patients undergoing valve replacement with the Starr-Edwards clothcovered steel ball prosthesis. Ann Surg 186:310, McHenry MM, Smeloff EA, Matlof HJ, et al: Long-term survival after single aortic or mitral valve replacement with the present model of Smeloff-Cutter valves. J Thorac Cardiovasc Surg 75:709, Messmer GJ, Okies JF, Hallman GL, et al: Mitral valve replacement with Bjork-Shiley tilting disc prosthesis. J Thorac Cardiovasc Surg 62:398, Mitha AS, Matisonn RE, le Roux BT, Chesler E: Clinical experience with the Lillehei-Kaster cardiac valve prosthesis. J Thorac Cardiovasc Surg 72:401, 1976 Discussion DR. EDWARD A. SMELOFF (Sacramento, CA): I thank Dr. David Starr and his colleagues for their careful review of a major series of aortic valve replacements. They bring to our attention the low incidence of thromboembolism regardless of anticoagulant status and provide another look at this situation. They suggest the possibility that the use of Coumadin (sodium warfarin) may not be as desirable as antiplatelet drugs if the complications of bleeding are added to the incidence of thromboembolism. Our experience covers 15 years-from 1964 through 1979-and 298 individuals having aortic valve replacement and surviving 1,420 patient-years. Only 1 patient maintained on Coumadin has sustained a popliteal thrombus. This patient had a thrombectomy of the popliteal artery preoperatively following heart catheterization. One patient fully anticoagulated died of thrombosis of the valve one month after a thrombosed Starr valve was replaced. One patient had a serious nonfatal cerebrovascular accident when Coumadin was stopped, and 2 patients who discontinued Coumadin abruptly were found at postmortem examination to have thrombosis about the prosthesis. Twelve patients representing 88 patient-years who were never placed on a regimen of Coumadin but were administered aspirin or Persantine (dipyridamole) or both have had no incidence of thromboembolism. In light of these observations, the use of Coumadin with its complications must be reconsidered for patients undergoing aortic valve replacement. Thromboembolism in conjunction with mitral valve replacement remains more significant, seen late as subvalvular fibrosis in 12 of 220 patients. Again, I emphasize that many of these events occurred after discontinuance of Coumadin. Perhaps design changes under study will improve this situation. When any prosthesis is under discussion, it is interesting to know the causes for and the incidence of its replacement. Although the authors did not include these data, I hope they might comment. In our total experience with 518 replacements since 1964, there have been 39 reoperations. Of 298 patients having aortic valve replacement, 19 were reoperated on, 9 for ball variance before 1966,l after 1966 for ball

7 454 The Annals of Thoracic Surgery Vol 30 No 5 November 1980 variance secondary to abrasion, 8 for dehiscence, and 1 for bacterial endocarditis. None were operated on for thrombosis. Of 220 patients having mitral valve replacement, 20 were reoperated on, 5 for ball variance before 1966, none for ball variance after 1966, 3 for dehiscence, and 12 with subvalvular fibrosis. Three of these last were children not on a regimen of anticoagulants. Since ball variance as a problem was eliminated in 1966, dehiscence remains the major cause of reoperation. It is apparent that the defect is primarily in technique rather than with the prosthesis. The technique has improved since we began inserting larger sizes than previously. No valves have required replacement because of structural failure of the prosthesis. In closing, I thank Drs. Starr, Lawrie, Howell, and Morris for this provocative review of a durable prosthesis that probably can be safely used with antiplatelet drugs alone. DR. JURO WADA (Tokyo, Japan): I was chairman at Sapporo Medical College Hospital for 23 years. There I had experience with 56 Smeloff-Cutter valves in the aortic position. Five-year actuarial long-term survival was 85%. No anticoagulation was employed. This result is about 10% better than my experience with 34 Starr-Edwards ball valve aortic implantations. Retrospectively, the Smeloff valve is nonthrombogenic and durable. I think the self-washing mechanism in the design of the Smeloff valve plays a more important role in preventing thromboembolic complications than the materials used in valve design. I incorporated this mechanism in the Wada- Cutter or hingeless valve-origin of the currently popular tilting-disc valve and St. Jude Medical prosthesis. DR. LAWRIE: We certainly regard it as a privilege to have Dr. Smeloff comment on the use of his valve. Initially, we were attracted to the use of this valve because of two features: the possible hemodynamic benefits of the equatorial ball, and the possibility of a lower rate of thromboembolism due to the open cage and the self-washing mechanism. I think the hemodynamics were perhaps marginally better than those of the comparable non-cloth-covered Starr-Edwards valve but they no longer stand as a major advantage of this valve. However, I think the evidence that we have heard today does suggest that the patient with a Smeloff-Cutter valve who is not on a regimen of anticoagulants is somewhat better off than a similar patient with a non-cloth-covered Starr-Edwards valve and certainly a patient with a cloth-covered Starr- Edwards valve. I think the patient on aspirin and Persantine (dipyridamole) is reasonably well protected with the Smeloff-Cutter valve, and for us this is pretty much a routine form of protection. Optimal protection will be achieved only with anticoagulation, but we have been discouraged by the morbidity. We continue to use this valve. We have used it for 12 years, and it is still our primary choice. We have not and still cannot see the advantage in most cases of using a Hancock valve. These valves have a poor orifice to annulus ratio. We now see these major problems in terms of durability in the very patients in whom we need durability most. We have a 15-year durability with only one instance of mechanical failure with the Smeloff-Cutter valve. Dr. Smeloff reported it today. I have always been disappointed in the quality of the sewing ring ever since the aortic Hancock valve was introduced. It seems thin and lacking in padding. We are now hearing reports of an unduly large incidence of periprosthetic leak with the use of this valve. For all these reasons, we have continued to use the Smeloff-Cutter valve, and I think we have been rewarded by a remarkably low rate of reoperation. This rate is 1 to 2%, and reoperation occurs primarily in patients with a severely calcific aortic valve who required reoperation because of erosion of the annulus. Over the next few years we have the opportunity to look in more detail at the question of the patient who is receiving no anticoagulants. Baylor College of Medicine is currently operating a full-time cardiac service in the Kingdom of Saudi Arabia. Under frontier conditions, it is not possible to maintain patients on any kind of anticoagulant regimen. Our early experience suggests that these patients do rather better than Western patients who receive no anticoagulants. The somewhat undernourished individuals with a low protein intake appear to have a degree of natural anticoagulation. We have introduced the Smeloff-Cutter valve on this service and so far have been very gratified with the results.