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Aortic valve replacement: One-year results with Lillehei-Kaster and Bjork-Shiley disc prosthesis
Aortic valve Liliehei-Kaster A comparative
repiacement: One-year results with and Bjork-Shiley disc prosthesis clinical study
Sigurd Nitter-Hauge, M.D. Karl-Victor Hall, M.D. Tor Froysaker, M.D. Leif Efskind, M.D. Oslo, Norway
The hemodynamic and functional advantages reported with the new Lillehei-Kaster pivoting disc valve and the Bjork-Shiley tilting disc valve prosthesis in patients with aortic valve disease have been encouraging, although the follow-up has not been long.1-4Data from a clinical trial permitting a’ direct comparison between long-term results with the two types of these new prostheses have also been lacking, but should be of considerable interest. For the latter purpose, we have used the two disc prostheses in a randomized study in the years 1971 and 1972, inserting one of them alternatively in patients with aortic valvular disease. This report deals with our clinical results in the first 68 patients re-examined 12 months after the operation. Material
and methods
The present study includes 68 patients with aortic stenosis and/or insuiIiciency who underwent operation with disc valve replacement in the period from 1971 to 1972. In most patients, the valvular lesions appeared to be of rheumatic or congenital origin. In a few patients there was a history of acute or subacute bacterial endocarditis. Associated mitral valve disease was observed in 19 patients, but none of them were treated with concomitant mitral valve surgery. There were 54 men and 14 women. From Medical Department B and Surgical Hospital, Rikshaspitalet,Oslo, Norway. Received for publication Oct. 22, 1973.
Department
Reprint requests to: Sigurd Nitter-Hauge, Medical University Hospital, Rikshwpitalet, Oslo 1, Norway.
July, 1974, Vol. 88, No. 1, pp. 23-28
A, University
Department
B,
Prior to operation, the patients were randomized, and a Lillehei-Kaster or a Bjork-Shiley (Delrin) disc prosthesis was inserted alternatively. Table I shows that, preoperatively, the average age, average heart volume, distribution of cases with various types of aortic valve lesions, and distribution of cam with various grades of functional disability were the same in the two groups of patients. The aortic valve was approached through a midsternal incision. Total cardiopulmonary bypass with hemodilution and mild hypothermia was employed, and the left coronary artery perfused continuously in all patients. Anticoagulation therapy with warfarin was given routinely, postoperatively. The follow-up ranged from 12 to 15 months, and the follow-up information was obtained by re-admitting the patients to hospital for about one week’s stay. They were carefully investigated by clinical examination. The functional capacity limited by angina pectoris or dyspnea preoperatively, as well as at the time of the re-examination, was established in personal interviews. The patients were grouped in four classes (I through IV) for functional cardiac capacity according to the criteria defined by the New York Heart Association.6 Almost all patients underwent cardiac catheterization with aortography, while transseptal catheterization was not done. Aortic regurgitation was assessed semiquantitatively, and was classified as follows: none or slight, moderate, and severe. Badiologic heart size was determined in all cases.
American
Heart Journal
23
Nittediauge
et al.
N.Y.H.A. c L
ASS
I
II
III
E 68 Pts Preop Fig. 1. The functional vivors of aortic valve Lillehei-Kasterpivoting valve.
improvement replacement. disc valve
-68
PfS Postop
experienced by the surOne year’s results with a or a BjtTrk-Shiley tilting disc
The statistical significance between pre- and postoperative findings as well as differences between the two groups of patients was tested by Student’s t test.6P-values higher than 0.05 were not considered to be significant. Results Subjective improvement. A comparison between functional cardiac capacity immediately before the operation and one year after the operation is given in Fig. 1. Symptomatically, most of the patients experienced definite improvement (Classes I and II, according to the N. Y. H. A. classification). Of the 68 patients re-examined, a total of 45 or 67 per cent considered themselves in a better condition than before operation. Eighteen patients were free of symptoms (26 per cent) and another 42 patients (62 per cent) had only minor complaints of car-
24
diac symptoms present as dyspnea or angina pectoris on exertion (N. Y. H. A., Classes I and II). A total of 8 patients or 12 per cent were still markedly incapacitated (N. Y. H. A., Classes III and IV). There was no difference in functional improvement between patients with a LilleheiKaster prosthesis compared to those with a Bjbrk-Shiley prosthesis (Table II). Although a definite symptomatic improvement was registered in most of the patients with additional mitral disease, five of the 19 patients in this subgroup were in functional Classes III and IV (N. Y. H. A) one year after the operation. Radiologic heart volume. Radiologic heart volume before and 12 months after operation was available in all but three patients. A comparison between data from these two examinations is given in Fig. 2. Most cases with pure aortic disease showed a slight to definite decline in heart volume following operation. In these patients, mean heart volume following insertion of the Lillehei-Kaster prosthesis was reduced from 680 to 584 ml. per square meter of body surface area and after insertion of a BjSrk-Shiley prosthesis from 605 to 502 ml. per square meter of body surface area. Both these reductions were significant (0.01 > p > 0.001). In contrast, the small group of patients with mitral disease in addition had, in general, unchanged heart volume values upon re-examination. In the group with the Lillehei-Kaster prosthesis, mean heart volume before operation was 711 ml. per square meter of body surface area versus 678 ml. per square meter of body surface area at the one year examination, and corresponding values after insertion with a Bjork-Shiley prosthesis were 692 ml. per square meter of body surface area and 780 ml. per square meter of body surface area. The difference between pre- and postoperative values were statistically not significant (p ) 0.05). Left ventricular hypertrophy. In 34 patients with pure aortic disease, it was possible to evaluate the functional results by measuring the combined voltage in precordial leads before and one year after the operation. The remaining 15 patients with pure aortic disease had either a right or left bundle branch block or pacemaker. The results are shown in Fig. 3. The combined voltage of SV, + RV, decreased distinctly from a mean value of 53 mm. to 36 mm. in patients with a Lillehei-Kaster prosthesis and from 49 mm. to 34
July, 1974, Vol. 88, No. 1
Aortic
SV,t
z 0 h4
valve replacement
RV5
80
-
60
-
40
-
20
-
.
L,llehes-Kaster
0
*1.rlc-
Sh,,ey
L Y L 0 cc Y + Y *
II
1
I
11
400
200
600
1 600
I
11
1200
ml/M2 BEFORE
I/
*
,000
I. Comparison
,
1
I
40
I
I
findings
1
60
60
BS4
SV,+RV5 OPERATION
BEFORE
between preoperative -
I
20
OPERATION
Fig. 2. Radiologic heart volume before and one year after single aortic valve replacement. Patients with additional mitral valvular disease are marked with a dash.
Table
I
0
Fig. 3. Comparison between combined voltage before and one year after single aortic valve
in two randomized
of SV 1 t KV 5 replacement.
groups of patients
Type of valve lesion Tyr-= of prostheses inserted
Average CYYSY,
Average heart volume ~ml.lM.2R!3A)
AS
AI
AS +AI
ASIAI + Mitr.
N Y H. A. classification I
II
III
IV
Lillehei-Kaster (n = 33)
52.4 (36-64)
697 (435-1,200)
1
13
10
9
1
14
13
5
Bjork-Shiley (n = 35)
51.5 (15-67)
634 (350-1,070)
5
7
13
10
0
13
12
10
mm. in patients with a Bjork-Shiley prosthesis. For both groups, the reduction in combined voltage in precordial leads was statistically significant (p (0.0011. Valvutar regurgitation. Follow-up aortography was done in 59 patients, and was omitted in 9 patients. This was mainly due to reluctance of the patients to be subjected to another catheterization while they were feeling well. Regurgitation at follow-up aortography was classified as in Table III. It is evident that patients with a BjorkShiley prosthesis showed somewhat greater valvular regurgitation than patients with a Lillehei-Kaster prosthesis, but in both groups the number of patients with more severe insufficien-
American
Heart JournaL
cy was small. None of the patients had to be operated upon. The incidence of paravalvular leakage was higher in patients with a Bjiirk-Shiley prosthesis than in those with a Lillehei-Kaster prosthesis. The paravalvular leaks ranged from small to more massive, but were usually small fistulas, and only one patient had to be reoperated upon. Discussion
Aortic valve replacement has become a wellestablished procedure in the treatment of patients with aortic valve disease, and results from follow-up studies of large series have been reported over the past years. Most studies in this field, however, have been based on examinations
25
Nitter-Hauge
et al.
Table II. The functional improvement experienced by survivors of aortic valve replacement in a comparative study between Lillehei-Kaster and Bjtirk-Shiley disc prostheses. Figures in brackets refer to patients with mitral valve disease in addition Lillehei-Kaster N. Y. H. A. classification
Preoperative
l(O)
I II III IV
14(l) 13(5) 5(3)
Table Ill. Results
of follow-up aortic disc valve prosthesis
aortography
following
Bjark-Shiley Postoperative
Preoperative
9t2) 20(5) 3(l) l(l)
replacement
0 13(l) 12(6) lO(3)
of
None or slight Moderate Severe Paravalvular
of patients with ball-valve prostheses of different construction, while informative data regarding the long-term results after insertion of the new disc-valve prothesis are more scanty. This is particularly true when discussing the new LilleheiKaster prosthesis. In the present study, a total of 68 patients have been re-examined one year after single aortic valve replacement with either the Lillehei-Kaster pivoting disc prosthesis or the Bjork-Shiley tilting disc prosthesis. The patients were randomized prior to operation, and one of these two disc prostheses was inserted alternatively. The results showed that the majority of patients had experienced a marked clinical improvement with relief of symptoms (up one or two functional classes according to N. Y. H. A.). Nearly 90 per cent of the patients were either asymptomatic and able to live a normal physical life or had mild dyspnea on effort (N. Y. H. A. Classes I and II). The good results obtained in the patient group with the Bjbrk-Shiley prosthesis are in accordance with other recently published follow-up studies with this prosthesis. Both
26
9(2) 22(5) 3(2) l(1)
with Lillehei-Kaster Z)pe
Clussification reg7qitation
Postoperative
or Bjork-Shiley
of prostheses Bjark-Shiley fn = 32)
Lillekei-Kaster fn = 27) 24 2 1
16 14 2
4
7
Bjork, Olin, and Rodriguez2 as well as Fernandez and associates? have reported that approximately 90 per cent of their patients were either in excellent condition, free of symptoms, or experienced mild dyspnea on effort, and less than 10 per cent complained of shortness of breath or (in a few cases) signs of congestive heart failure. In a third study, Messmer and co-workers4stated that one or two years after operation, 71 per cent of the patients with a Bjark-Shiley tilting disc valve prosthesis were in Classes I or II (N. Y. H. A.). The functional status after insertion of a LilleheiKaster pivoting disc valve is less well known. Our results indicate that the clinical improvement following replacement with the aforementioned prosthesis is just as good as with the Bjdrk-Shiley prosthesis used in the present study. The good functional results following replacement with either of the two prostheses are supported by the finding of a decrease in heart volume and a decrease in voltage in precordial leads. The results from the follow-up evaluation of a small number of patients who had mitral valve disease in addition to aortic valve disease should
July,
1974,
Vol.
SS, No.
1
Aortic
be commented upon more closely. The mitral valve disease in these patients was thought to be of little hemodynamic significance, not necessitating surgical correction. The postoperative evaluation showed that, irrespective of which of the two types of prostheses had been. inserted, the functional improvement in this group was less obvious than in patients with pure aortic stenosis, and that the heart volume in general had remained unchanged. The lesser reduction in heart volume seen in this subgroup compared to that in patients with pure aortic disease may be due to the fact that patients with mitral valve disease have impairment of myocardial function due to a low output state, atria1 fibrillation, pulmonary vascular disease, and tricuspid valvular disease.7These factors will persist after single aortic valve replacement and might have been responsible for the persistence of the cardiac enlargement. Based on findings at aortography, we found that the regurgitation through the Bjork-Shiley prosthesis was greater than in patients with a Lillehei-Kaster prosthesis. Most probably, the reason for this observation is that the former prosthesis does not occlude the ring during diastole, while the backflow with the LilleheiKaster prosthesis is minimal. For both types of prostheses, however, the amount of aortic regurgitation seen in the aortograms was considered to be mild or moderate. In the present study, we were not able to demonstrate that this difference in prosthesis design was of any importance for the symptomatic improvement and functional status seen one year after the operation. The functional improvement experienced by the survivors in the present study does not seem to differ from results achieved in a large series of patients after successful insertion of other types of prostheses.6 Thus the introduction of these new types of aortic valve prostheses does not seem to influence late functional results. This is illustrated by the fact that our results do not differ from the results in a similar clinical evaluation of a large group of patients following replacement with single aortic ball-valve prostheses published from this hospital by Storstein and Efskind.g However, it should be added that patients with the two types of disc prostheses distinguish themselves from patients with ball valves by having a definite lesser incidence
American
Heart Journal
valve replacement
of hemolysis, as shown by us in a recent study.lOIt has also been claimed that the patients with the new disc valves should be less inclined to late thromboembolic complications than patients with an aortic ball-valve prosthesis. So far, no thromboembolic episodes have been observed in the present series, but the follow-up period is too short to reach final conclusions. Summary
The present study presents clinical and functional results obtained in a randomized series of 68 patients examined one year after single aortic valve replacement with either a Lillehei-Kaster pivoting disc valve or a Bjork-Shiley tilting disc valve. Symptomatic improvement was experienced in 67 per cent of all patients re-examined, and 88 per cent were in functional Classes I and II. In patients with pure aortic valve disease, heart volume was significantly reduced, while a small group of patients with mitral valve disease, in addition, had unchanged or slightly increased heart volume. Regression of left ventricular hypertrophy in the electrocardiogram was also noted in most patients. It is felt that the clinical and functional results may be of the same order of magnitude in patients with the Lillehei-Kaster model as in patients with the Bjork-Shiley prosthesis.
REFERENCES 1.
2.
3.
4.
5.
6. 7.
8.
Lillehei, C. W., Carlson, R. G., Kaster, R. L., Bloch, J. H., Nitter-Hauge, S., Hall, K. V., and Efskind, L.: Clinical experience with the new central pivoting disc aortic and mitral prosthesis. Surgery In press. Bjork, V. O., Olin, C., and Rodriguez, L.: Comparative results of aortic valve replacement with different prosthetic heart valves, J. Cardiovasc. Surg. 13~266, 1972. Fernandez,J., Maranhao, V., Gooch,A. S., Morse, D., and Nichols, H. T.: The Bjiirk-Shiley prosthesis. A significant advance in aortic valve replacement, Ann. Thorac. Surg. 14527, 1972. Messmer, B. J., Okis, J. E., Hallman, G. L., and Cooley, D. A.: Aortic valve replacement: Two years’ experience with the Bj”ork-Shiley tilting-disc prosthesis, Surgery 72~772, 1972. New York Heart Association. Nomenclature and criteria for diagnosis of diseases of the heart and blood vessels, Ed. 5, 1953. Snedecor, G. W.: Statistical methods, Ames, Iowa. 1956, Iowa State College Press. Rastelli, G. C., Kincaid, 0. W.. and Kirkhn, J. W.: Heart size after isolated replacement of mitral or aortic valve. Proc. Staff Mayo Clin. 41:217, 1966. Morrow, A. G., Oldham, H. N., Elkins. R. C., and Braun-
27
Nitter-Hauge
9.
28
et al.
wald, E.: Obstruction to left ventricular outflow. Cur rent concepts of management and operative treatment, Ann. Intern. Med. 661255, 1968. Storstein, O., and Efskind, L.: Immediate and late results of aortic ball-valve replacement, Stand. J. Thorac. Cardiovasc. Surg. 6:114, 1972.
16.
Nitter-Hauge, S., T., and Efskind, after aortic valve tween Lillehei-Kaster thesis, Br. Heart
Sommerfelt, S., Hall, K. V., FGysaker, L.: Chronic intravascular haemolysis replacement: a comparative study beand Bjgrk-Shiley disc-valve prosJ. In press.
July, 1974, Vol. 88, No. 1
repiacement: One-year results with and Bjork-Shiley disc prosthesis clinical study
Sigurd Nitter-Hauge, M.D. Karl-Victor Hall, M.D. Tor Froysaker, M.D. Leif Efskind, M.D. Oslo, Norway
The hemodynamic and functional advantages reported with the new Lillehei-Kaster pivoting disc valve and the Bjork-Shiley tilting disc valve prosthesis in patients with aortic valve disease have been encouraging, although the follow-up has not been long.1-4Data from a clinical trial permitting a’ direct comparison between long-term results with the two types of these new prostheses have also been lacking, but should be of considerable interest. For the latter purpose, we have used the two disc prostheses in a randomized study in the years 1971 and 1972, inserting one of them alternatively in patients with aortic valvular disease. This report deals with our clinical results in the first 68 patients re-examined 12 months after the operation. Material
and methods
The present study includes 68 patients with aortic stenosis and/or insuiIiciency who underwent operation with disc valve replacement in the period from 1971 to 1972. In most patients, the valvular lesions appeared to be of rheumatic or congenital origin. In a few patients there was a history of acute or subacute bacterial endocarditis. Associated mitral valve disease was observed in 19 patients, but none of them were treated with concomitant mitral valve surgery. There were 54 men and 14 women. From Medical Department B and Surgical Hospital, Rikshaspitalet,Oslo, Norway. Received for publication Oct. 22, 1973.
Department
Reprint requests to: Sigurd Nitter-Hauge, Medical University Hospital, Rikshwpitalet, Oslo 1, Norway.
July, 1974, Vol. 88, No. 1, pp. 23-28
A, University
Department
B,
Prior to operation, the patients were randomized, and a Lillehei-Kaster or a Bjork-Shiley (Delrin) disc prosthesis was inserted alternatively. Table I shows that, preoperatively, the average age, average heart volume, distribution of cases with various types of aortic valve lesions, and distribution of cam with various grades of functional disability were the same in the two groups of patients. The aortic valve was approached through a midsternal incision. Total cardiopulmonary bypass with hemodilution and mild hypothermia was employed, and the left coronary artery perfused continuously in all patients. Anticoagulation therapy with warfarin was given routinely, postoperatively. The follow-up ranged from 12 to 15 months, and the follow-up information was obtained by re-admitting the patients to hospital for about one week’s stay. They were carefully investigated by clinical examination. The functional capacity limited by angina pectoris or dyspnea preoperatively, as well as at the time of the re-examination, was established in personal interviews. The patients were grouped in four classes (I through IV) for functional cardiac capacity according to the criteria defined by the New York Heart Association.6 Almost all patients underwent cardiac catheterization with aortography, while transseptal catheterization was not done. Aortic regurgitation was assessed semiquantitatively, and was classified as follows: none or slight, moderate, and severe. Badiologic heart size was determined in all cases.
American
Heart Journal
23
Nittediauge
et al.
N.Y.H.A. c L
ASS
I
II
III
E 68 Pts Preop Fig. 1. The functional vivors of aortic valve Lillehei-Kasterpivoting valve.
improvement replacement. disc valve
-68
PfS Postop
experienced by the surOne year’s results with a or a BjtTrk-Shiley tilting disc
The statistical significance between pre- and postoperative findings as well as differences between the two groups of patients was tested by Student’s t test.6P-values higher than 0.05 were not considered to be significant. Results Subjective improvement. A comparison between functional cardiac capacity immediately before the operation and one year after the operation is given in Fig. 1. Symptomatically, most of the patients experienced definite improvement (Classes I and II, according to the N. Y. H. A. classification). Of the 68 patients re-examined, a total of 45 or 67 per cent considered themselves in a better condition than before operation. Eighteen patients were free of symptoms (26 per cent) and another 42 patients (62 per cent) had only minor complaints of car-
24
diac symptoms present as dyspnea or angina pectoris on exertion (N. Y. H. A., Classes I and II). A total of 8 patients or 12 per cent were still markedly incapacitated (N. Y. H. A., Classes III and IV). There was no difference in functional improvement between patients with a LilleheiKaster prosthesis compared to those with a Bjbrk-Shiley prosthesis (Table II). Although a definite symptomatic improvement was registered in most of the patients with additional mitral disease, five of the 19 patients in this subgroup were in functional Classes III and IV (N. Y. H. A) one year after the operation. Radiologic heart volume. Radiologic heart volume before and 12 months after operation was available in all but three patients. A comparison between data from these two examinations is given in Fig. 2. Most cases with pure aortic disease showed a slight to definite decline in heart volume following operation. In these patients, mean heart volume following insertion of the Lillehei-Kaster prosthesis was reduced from 680 to 584 ml. per square meter of body surface area and after insertion of a BjSrk-Shiley prosthesis from 605 to 502 ml. per square meter of body surface area. Both these reductions were significant (0.01 > p > 0.001). In contrast, the small group of patients with mitral disease in addition had, in general, unchanged heart volume values upon re-examination. In the group with the Lillehei-Kaster prosthesis, mean heart volume before operation was 711 ml. per square meter of body surface area versus 678 ml. per square meter of body surface area at the one year examination, and corresponding values after insertion with a Bjork-Shiley prosthesis were 692 ml. per square meter of body surface area and 780 ml. per square meter of body surface area. The difference between pre- and postoperative values were statistically not significant (p ) 0.05). Left ventricular hypertrophy. In 34 patients with pure aortic disease, it was possible to evaluate the functional results by measuring the combined voltage in precordial leads before and one year after the operation. The remaining 15 patients with pure aortic disease had either a right or left bundle branch block or pacemaker. The results are shown in Fig. 3. The combined voltage of SV, + RV, decreased distinctly from a mean value of 53 mm. to 36 mm. in patients with a Lillehei-Kaster prosthesis and from 49 mm. to 34
July, 1974, Vol. 88, No. 1
Aortic
SV,t
z 0 h4
valve replacement
RV5
80
-
60
-
40
-
20
-
.
L,llehes-Kaster
0
*1.rlc-
Sh,,ey
L Y L 0 cc Y + Y *
II
1
I
11
400
200
600
1 600
I
11
1200
ml/M2 BEFORE
I/
*
,000
I. Comparison
,
1
I
40
I
I
findings
1
60
60
BS4
SV,+RV5 OPERATION
BEFORE
between preoperative -
I
20
OPERATION
Fig. 2. Radiologic heart volume before and one year after single aortic valve replacement. Patients with additional mitral valvular disease are marked with a dash.
Table
I
0
Fig. 3. Comparison between combined voltage before and one year after single aortic valve
in two randomized
of SV 1 t KV 5 replacement.
groups of patients
Type of valve lesion Tyr-= of prostheses inserted
Average CYYSY,
Average heart volume ~ml.lM.2R!3A)
AS
AI
AS +AI
ASIAI + Mitr.
N Y H. A. classification I
II
III
IV
Lillehei-Kaster (n = 33)
52.4 (36-64)
697 (435-1,200)
1
13
10
9
1
14
13
5
Bjork-Shiley (n = 35)
51.5 (15-67)
634 (350-1,070)
5
7
13
10
0
13
12
10
mm. in patients with a Bjork-Shiley prosthesis. For both groups, the reduction in combined voltage in precordial leads was statistically significant (p (0.0011. Valvutar regurgitation. Follow-up aortography was done in 59 patients, and was omitted in 9 patients. This was mainly due to reluctance of the patients to be subjected to another catheterization while they were feeling well. Regurgitation at follow-up aortography was classified as in Table III. It is evident that patients with a BjorkShiley prosthesis showed somewhat greater valvular regurgitation than patients with a Lillehei-Kaster prosthesis, but in both groups the number of patients with more severe insufficien-
American
Heart JournaL
cy was small. None of the patients had to be operated upon. The incidence of paravalvular leakage was higher in patients with a Bjiirk-Shiley prosthesis than in those with a Lillehei-Kaster prosthesis. The paravalvular leaks ranged from small to more massive, but were usually small fistulas, and only one patient had to be reoperated upon. Discussion
Aortic valve replacement has become a wellestablished procedure in the treatment of patients with aortic valve disease, and results from follow-up studies of large series have been reported over the past years. Most studies in this field, however, have been based on examinations
25
Nitter-Hauge
et al.
Table II. The functional improvement experienced by survivors of aortic valve replacement in a comparative study between Lillehei-Kaster and Bjtirk-Shiley disc prostheses. Figures in brackets refer to patients with mitral valve disease in addition Lillehei-Kaster N. Y. H. A. classification
Preoperative
l(O)
I II III IV
14(l) 13(5) 5(3)
Table Ill. Results
of follow-up aortic disc valve prosthesis
aortography
following
Bjark-Shiley Postoperative
Preoperative
9t2) 20(5) 3(l) l(l)
replacement
0 13(l) 12(6) lO(3)
of
None or slight Moderate Severe Paravalvular
of patients with ball-valve prostheses of different construction, while informative data regarding the long-term results after insertion of the new disc-valve prothesis are more scanty. This is particularly true when discussing the new LilleheiKaster prosthesis. In the present study, a total of 68 patients have been re-examined one year after single aortic valve replacement with either the Lillehei-Kaster pivoting disc prosthesis or the Bjork-Shiley tilting disc prosthesis. The patients were randomized prior to operation, and one of these two disc prostheses was inserted alternatively. The results showed that the majority of patients had experienced a marked clinical improvement with relief of symptoms (up one or two functional classes according to N. Y. H. A.). Nearly 90 per cent of the patients were either asymptomatic and able to live a normal physical life or had mild dyspnea on effort (N. Y. H. A. Classes I and II). The good results obtained in the patient group with the Bjbrk-Shiley prosthesis are in accordance with other recently published follow-up studies with this prosthesis. Both
26
9(2) 22(5) 3(2) l(1)
with Lillehei-Kaster Z)pe
Clussification reg7qitation
Postoperative
or Bjork-Shiley
of prostheses Bjark-Shiley fn = 32)
Lillekei-Kaster fn = 27) 24 2 1
16 14 2
4
7
Bjork, Olin, and Rodriguez2 as well as Fernandez and associates? have reported that approximately 90 per cent of their patients were either in excellent condition, free of symptoms, or experienced mild dyspnea on effort, and less than 10 per cent complained of shortness of breath or (in a few cases) signs of congestive heart failure. In a third study, Messmer and co-workers4stated that one or two years after operation, 71 per cent of the patients with a Bjark-Shiley tilting disc valve prosthesis were in Classes I or II (N. Y. H. A.). The functional status after insertion of a LilleheiKaster pivoting disc valve is less well known. Our results indicate that the clinical improvement following replacement with the aforementioned prosthesis is just as good as with the Bjdrk-Shiley prosthesis used in the present study. The good functional results following replacement with either of the two prostheses are supported by the finding of a decrease in heart volume and a decrease in voltage in precordial leads. The results from the follow-up evaluation of a small number of patients who had mitral valve disease in addition to aortic valve disease should
July,
1974,
Vol.
SS, No.
1
Aortic
be commented upon more closely. The mitral valve disease in these patients was thought to be of little hemodynamic significance, not necessitating surgical correction. The postoperative evaluation showed that, irrespective of which of the two types of prostheses had been. inserted, the functional improvement in this group was less obvious than in patients with pure aortic stenosis, and that the heart volume in general had remained unchanged. The lesser reduction in heart volume seen in this subgroup compared to that in patients with pure aortic disease may be due to the fact that patients with mitral valve disease have impairment of myocardial function due to a low output state, atria1 fibrillation, pulmonary vascular disease, and tricuspid valvular disease.7These factors will persist after single aortic valve replacement and might have been responsible for the persistence of the cardiac enlargement. Based on findings at aortography, we found that the regurgitation through the Bjork-Shiley prosthesis was greater than in patients with a Lillehei-Kaster prosthesis. Most probably, the reason for this observation is that the former prosthesis does not occlude the ring during diastole, while the backflow with the LilleheiKaster prosthesis is minimal. For both types of prostheses, however, the amount of aortic regurgitation seen in the aortograms was considered to be mild or moderate. In the present study, we were not able to demonstrate that this difference in prosthesis design was of any importance for the symptomatic improvement and functional status seen one year after the operation. The functional improvement experienced by the survivors in the present study does not seem to differ from results achieved in a large series of patients after successful insertion of other types of prostheses.6 Thus the introduction of these new types of aortic valve prostheses does not seem to influence late functional results. This is illustrated by the fact that our results do not differ from the results in a similar clinical evaluation of a large group of patients following replacement with single aortic ball-valve prostheses published from this hospital by Storstein and Efskind.g However, it should be added that patients with the two types of disc prostheses distinguish themselves from patients with ball valves by having a definite lesser incidence
American
Heart Journal
valve replacement
of hemolysis, as shown by us in a recent study.lOIt has also been claimed that the patients with the new disc valves should be less inclined to late thromboembolic complications than patients with an aortic ball-valve prosthesis. So far, no thromboembolic episodes have been observed in the present series, but the follow-up period is too short to reach final conclusions. Summary
The present study presents clinical and functional results obtained in a randomized series of 68 patients examined one year after single aortic valve replacement with either a Lillehei-Kaster pivoting disc valve or a Bjork-Shiley tilting disc valve. Symptomatic improvement was experienced in 67 per cent of all patients re-examined, and 88 per cent were in functional Classes I and II. In patients with pure aortic valve disease, heart volume was significantly reduced, while a small group of patients with mitral valve disease, in addition, had unchanged or slightly increased heart volume. Regression of left ventricular hypertrophy in the electrocardiogram was also noted in most patients. It is felt that the clinical and functional results may be of the same order of magnitude in patients with the Lillehei-Kaster model as in patients with the Bjork-Shiley prosthesis.
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July, 1974, Vol. 88, No. 1