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AORTIC VALVE PROSTHESIS (TEFLON)
AORTIC VALVE PROSTHESIS (TEFLON) Two Year Follow-Up V. 0. Bjork, M.D., I. Cullhed, M.D., and H. Lodin, M.D., Uppsala, Sweden
F
OR the treatment of most patients with acquired aortic stenosis and insufficiency, the use of a valve prosthesis is necessary. At present we do not know which prosthesis is ideal. The questions that always arise when individual cusps are replaced are: (1) Will the prosthetic cusps be competent immediately and remain so for a period of significantly long duration? (2) Will the continuous movements cause fatigue and break the plastic material? (3) Will tissue ingrowth cause thickening with decreased mobility, calcification, and progressive stenosis? The aim of this paper is to report the one year follow-up of a group of patients who underwent aortic valve replacement with individual cusps of Teflon, designed by Bahnson, or with a total prosthesis of Teflon, as designed by Muller. MATERIAL
Thirteen patients were accepted for aortic valve replacement; the youngest was 20 and the oldest 50 years of age. One patient had pure ealcific aortic stenosis, 3 had pure aortic insufficiency, and the remaining 9 had a combination of stenosis and insufficiency. The largest heart was 810 ml. per square meter of body surface area. The only heart with normal size (400 ml. per square meter) was in a patient with ealcific aortic stenosis and insufficiency with a peak systolic pressure gradient of 107 mm. Hg over the aortic valve. In 7 cases, calcifications were visible on tomography. SURGICAL T E C H N I Q U E
The heart-lung machine was started with a very small flow, usually 1 L. per minute for the first minutes until a clamp was placed on the ascending aorta. The perfusion rate was then increased to a calculated value of 2.2 L. per square meter of body surface area. From a side branch of the arterial line, blood was pumped through a catheter and through a special cannula held in the coronary ostia. The left coronary artery was perfused during almost the entire time the aortotomy was open. The right coronary artery was also perfused. The longest time for left coronary artery perfusion was 104 minutes and for right coronary perfusion was 29 minutes. The average perfusion time was 100 minutes (range, 61 to 146 minutes). F r o m t h e U n i v e r s i t y H o s p i t a l , U p p s a l a , Sweden. Received for p u b l i c a t i o n A u g . 23, 1962.
635
B J 6 B K , CULLHED, L O D I N
636
J. Thoracic and Cardiovas. Surg. TABLE I .
CASE
AGE
DIAGNOSIS
1 2 3 4
29 41 43 44
AS AS + A I AI AS + A I
5 6 7 8
20 24 50 39
AI AI AI AI
RHEUMATIC FEVER
CALCIFICATIONS (TOMOGRAM)
CLINICAL AND
HEART SIZE ( M L . / M . 2 BSA) EOLLOW-UP
-
+ + 0 +
/ . One Prosthetic Cusp 540 670 590 520 580 870 530 480
+
0 0 + 0
II. Three Prosthetic Cusps 540 445 650 830 570 460 640 475
0
III. Total Valve 650
+ +
-
+
41 9 AI •Pressures taken one year after operation. tAt operation.
Prosthesis 690
PRIMARY RESULT
In the first 4 cases in which only one aortic cusp was replaced, all patients survived. In 3 of them (Cases 1, 2, and 4) there was calcine aortic stenosis, combined with insufficiency in 2 cases. The primary result was good in these 3 cases. In the fourth case (Case 3), there was no calcification. The patient survived with remaining aortic insufficiency. Nine patients had removal of all cusps. Eight patients had replacement with individual cusps. Of these 8 patients, 4 died; one from remaining aortic insufficiency, one from infection one month after the operation, and one patient 12 days after an unsatisfactory repair in a very distorted and narrow calcific aortic ring. The fourth patient was a 50-year-old man having an aortic pressure gradient of 107 mm. Hg who first made a satisfactory recovery but died suddenly two weeks after operation when he was walking around in the ward. At autopsy the local result was excellent. The remaining 4 patients who had all three cusps replaced showed a good primary result. One patient had a dilated aortic ring with bicuspid aortic valves where both cusps were prolapsing. Replacement was performed with a Muller prosthesis, in which three Teflon cusps are mounted on a Teflon frame. The patient made a good recovery. TWO YEAR FOLLOW-UP
The pertinent clinical and hemodynamic findings at the two year follow-up are summarized in Table I. A. One Cusp Replaced.— In this group of 4 patients, 2 were improved (Cases 2 and 3) and 2 were not (Cases 1 and 4). CASE 1.—A 29-year-old man with calcific aortic stenosis and a maximal pressure gradient of 80 mm. H g had the noncoronary cusp replaced by a 30 mm. Teflon cusp. After operation the aortic gradient was abolished and the primary result was good. However, during the
5
Vol. 45, N o May, 1963
637
AORTIC VALVE P R O S T H E S I S
HEMODYNAMIC OBSERVATIONS AORTOGRAPHY DEGREE REGURG. BEFORE
|
LV P R E S S U R E ( R E S T ) *
FOLLOW-UP
BEFORE
| FOLLOW-UP
(0) ++ +++ ++
+++ + +++ ++
170/5 225/23 150/15 247/15
144/20
+++ +++ +++ +++
+ +++ 0 (+)
110/lOt 181/10 158/17t 135/12
171/18 130/21
+++
+++
165/10
P E A K SYSTOLIC GRADIENT ( R E S T ) BEFORE
FOLLOW-UP
IMPROVED
80 60 0 109
28 11 18
No Yes Yes? No
131/4
0 0 0 0
9 7 30 16
Yes No Yes Yes
195/10
0
9
141/15 198/22
No
following year the heart enlarged and a diastolic murmur became obvious. There was an aortic gradient of 70 mm. H g with a significant aortic insufficiency demonstrated by aortography. Thirteen months after the first operation, another operation was performed. The Teflon cusp showed a central rupture down to its base. I t was thickened, had decreased mobility, and seemed to be calcified. However, crystalography demonstrated protein but no calcium (Figs. 1 and 2 ) . The Teflon cusp as well as the calcified right and left cusps were removed and a ball valve prosthesis, according to Starr, was sutured in place. The patient made an uneventful recovery and is, after another year, in excellent condition. CASE 2.—A 41-year-old man had calcific aortic stenosis as well as a severe aortic insufficiency. The calcific left aortic cusp was excised and substituted by one 30 mm. Teflon cusp. The right and noncoronary cusps were fused together into one rigid calcific rock and were left in place. At the end of operation there only remained a 10 mm. H g gradient over the aortic ostium and the aortic insufficiency was completely abolished. After two years, the heart had diminished in size from 590 to 520 ml. per square meter. CASE 3.—A 43-year-old man with a history of rheumatic fever was found to have a combination of aortic stenosis and insufficiency. The fused commissure between the right and the noncoronary cusps was opened and one 42 mm. Teflon cusp replaced the noncoronary cusp. I t was noted at the time of operation that it would be difficult to obtain a complete competence without the use of a total prosthesis. A diastolic murmur remained and when the patient left the hospital it was obvious that he had a significant residual aortic insufficiency. As he feels improved, re-operation has been postponed. CASE 4.—A 45-year-old man with calcific aortic stenosis and insufficiency had the noncoronary cusp replaced by a 30 mm. Teflon cusp. An aortic gradient of 109 mm. H g was reduced to 18 mm. H g and the heart diminished in size, although the same degree of insufficiency remained after the operation. The patient is not subjectively improved, probably because of coronary artery disease.
B. AU Cusps Replaced.— CASE 5.—A 20-year-old man had a significant aortic insufficiency and a large heart. Three prolapsing cusps were replaced with three isolated Teflon cusps. After two years, the heart had diminished in size from 540 ml. to 445 ml. per square meter. There was a minimal residual insufficiency (at aortography a thin contrast leakage was observed immediately beneath the valvular area) and a resting aortic gradient of 21 mm. Hg, which, however, rose to 53 mm. H g on a work load of 600 kilograms per meter per minute (Figs. 3^4 and 3 B ) .
638
BJoRK, CULLHEI), LODIN
.1. Thoracic and Cardiovas. Surg.
Pig. 1.—Case 1. The aortic (A) and left ventricular view (B) of the ruptured Teflon cusp removed after 13 months. Note the thickened edges along the rupture. The base of the cusp was firmly healed in place.
Fig. 2.- -A roentgenogram of the removed Teflon cusp demonstrates the thickening along the rupture and the base of the cusp.
Vol. 45, No. 5 May, 1963
AORTIC VALVE P R O S T H E S I S
639
CASE 6.—A 25-year-old man with aortic insufficiency had an increase in heart size from 450 ml. to 650 ml. per square meter during 5 years. Three prolapsing cusps were found at operation and they were replaced by 3 Teflon cusps. Primary healing was uneventful and the patient left the hospital with competent aortic cusps. At follow-up, a free insufficiency was found and the heart was further dilated. Re-operation was advised but the patient did not accept. He died 2 months later. The Teflon cusps were found fragmented in the edges and there was a central hole, as well as dislocation, at the base of one of the cusps (Fig. 4 ) . The main insufficiency was caused by the dislocation at the base of one cusp.
Fig. 3.—Case 5. Postoperative examination (thoracic aortography). The valve prostheses show reduced mobility, especially the left and right, valves with formation of a dome (->) and a Jet (A). Slight incompetence in diastole (JB).
B J 6 R K , CULLHED, LODIN
640
J. Thoracic and Cardiovas. Surg.
CASE 7.—A 50-year-old man had calcific aortic stenosis with a gradient of 80 mm. Hg, which was abolished by transventricular dilatation. An aortic insufficiency present before operation was increased. The patient was improved for 1% year, but 2 years after the first operation his condition deteriorated and he was re-operated upon. The right aortic cusp was ruptured. Three isolated Teflon cusps were sutured in place after excision of all three aortic cusps. At follow-up, the heart had diminished from 530 ml. to 460 ml. per square meter. The resting aortic gradient was 27 mm. H g and the gradient at a work load of 600 kilograms per meter per minute did not increase to more than 31 mm. Hg. The insufficiency was completely abolished and the patient was free of symptoms (Figs. 5, A, B, and C).
Fig. 4.—Case 6. Autopsy specimen of a Teflon cusp after one year. The cusp was dislocated at its base with free insufficiency. Note fragmentation of Teflon edges. CASE 8.—A 39-year-old man, who had had rheumatic fever at the age of 11, had aortic regurgitation with a dilated heart. At operation three prolapsing cusps were excised and replaced with three Teflon cusps. At follow-up a perfect result was found with reduction in heart size from 640 ml. to 475 ml. per square meter. A resting aortic gradient of 16 mm. H g was found. The aortography showed thickened but completely competent aortic cusps (Figs. 6A, B, and C). CASE 9.—A 41-year-old man had aortic insufficiency with a large heart—650 ml. per square meter. At operation a bicuspid aortic orifice was found and the two prolapsing cusps were excised. In this case it was necessary to use a total valve prosthesis and the one described by Muller was used. At one year follow-up the heart had not diminished in size, but the insufficiency was completely abolished and no gradient was found. However, at a 1% year follow-up, a free aortic regurgitation had re-appeared. At re-operation, this was found to be due to a rather small distal perforation in one of the 3 cusps mounted on a Teflon frame. The patient died one week after re-operation. DISCUSSION
This two year follow-up has showed that in the majority of cases a good functional result can be obtained. However, tissue ingrowth and deposition of protein and fibrin has caused a significant thickening of the Teflon cusps.
Vol.45, No. 5 May, 1963
AORTIC VALVE PROSTHESIS
641
Fig. 5.—Case 7. Systole (A). Diastole (B-C). Postoperative examination. Thoracic aortography. The valve prostheses show reduced mobility with backward directed jet (->) in systole. The cusps, especially the noncoronary one, are thick and with irregular contours. Where the base of the noncoronary and right valve prosthesis were sutured together, there is a pea-sized contrast defect (C) (parietal thrombus?). No incompetence.
642
B.T5BK, CULT.HEB, LODTN
J. Thoracic and Cardiovas. Surg.
Fig. 6.—Case 8. A, Preoperative examination. Thoracic aortography. Extreme aortic insufficiency.
This thickening will diminish the mobility of the cusp and cause some degree of stenosis, so far only with a small gradient. However, in one case (Case 5) a gradient of 21 mm. Hg at rest and 53 mm. Hg on exercise was found. It is thus obvious that the stiffening is pronounced enough to cause a slight but definite gradient over the aortic orifice in most cases. Angiocardiographic studies have furthermore demonstrated this decreased mobility, although in the majority of cases there was a complete competence during diastole. It was found that in systole the cusps opened only partly. In some cases the thickening was clearly visible and irregularities on the prosthetic cusps suggested ingrowth of tissue and deposits of fibrin. The ability to obtain completely competent valves is most encouraging. However, the decreased mobility, as demonstrated by angiocardiography as well as with pressure measurements, is of sufficient importance to question the
Vol. 45, No. 5 May, 1963
AORTIC VALVE PROSTHESIS
643
Fig. 6.—B and G, Postoperative examination. The valve prostheses (<—► ) are slightly thickened but show good mobility. (B) Systole; (C) diastole. No insufficiency visible.
644
BJORK, CULLHED,
LOD1N
J. Thoracic and Cardiovas. Surg.
advisability of using this material, as, already after one year, a slight but definite stenosis has been observed, with decreased mobility and irregularities of the cusps. I t is probable that these changes may progress to produce more severe stenosis in the longer follow-up. The most important observation, however, is that a thickened Teflon cusp ruptured down to its base and caused severe insufficiency. It can naturally be argued that in this case a monocusp was used which was constantly beating against the calcific aortic cusps left in place. It is, however, most probable that a thickened cusp will more easily wear out and break the plastic material. This has been proved in 3 cases. The question arises: Will more such ruptures occur as time goes by? I t is the obvious conclusion that aortic valve prostheses of Teflon permit tissue ingrowth, do not maintain an ideal function, and may rupture after one year. Therefore, a more satisfactory material must be sought for aortic valve replacement. We will continue to follow our cases but after this experience we do not at present use Teflon cusps but are using a ball valve prosthesis, first advocated by Harken and then perfected by Starr and manufactured by Edwards. AVe only advise total aortic valve replacement in patients who are in a late and severe stage of their disease. SUMMARY
A follow-up study with angiocardiography and left heart catheterization of patients who have had the aortic valve replaced by a prosthesis with Teflon cusps has been presented. Due to tissue ingrowth and thickening of the Teflon cusps, a decreased mobility has been noted. These irregularities and thickening of the cusps have caused slight but definite aortic stenosis, demonstrated as well by angiocardiography as by pressure measurements. In 3 cases the thickened Teflon aortic cusp ruptured and had to be replaced by a ball valve prosthesis in 2 cases. REFERENCES
1. Bahnson, H. T., Spencer, F . C , Busse, E . F . 6., and Davis, F . W . : Cusp Replacement and Coronary Artery Perfusion in Open Operations on the Aortic Valve, Ann. Surg. 152: 494, 1960. 2. Bahnson, H. T., Spencer, F . C , and Norman, C. J . : Experiences With Replacement of Iidividual Cusps of the Aortic Valve in Prosthetic Valves for Cardiac Surgery, Springfield, 111., 1961, Charles C Thomas, Publisher. 3. Hufnagel, C. A.: Direct Approach For The Treatment of Aortic Insufficiency. Am. Surgeon 25: 321, 1959. 4. Lillehei, C. W., Gott, V. L., DeWall, R. A., and Varco, R. L . : The Surgical Treatment of Stenotic or Regurgitant Lesions of the Mitral and Aortic Valves By Direct Vision Utilizing A Pump-Oxygenator, J .
THORACIC SURG. 35: 154, 1958.
5. Long, D. M., Sterns, L. P., DeRiemer, R. H., Warden, H. E., and Lillehei, C. W.: Subtotal and Total Replacement of the Aortic Valve With Plastic Valve Prostheses: Experimental Investigation and Successful Clinical Application Utilizing Selective Cardiac Hypothermia, S. Forum 1 0 : 160, 1960. 6. McGoon, D. C.: Prosthetic Reconstruction of the Aortic Valve, Proc. Staff Meet. Mayo Clin., Feb. 15, 1961. 7. Muller, W. H., J r . , Warren, W. D., Dammann, ,T. F . , Jr., Beckwith, J . R., and Wood, E. J., J r . : Surgical Relief of Aortic Insufficiency by Direct Operation on the Aortic Valve, Circulation 21: 587, 1960.
F
OR the treatment of most patients with acquired aortic stenosis and insufficiency, the use of a valve prosthesis is necessary. At present we do not know which prosthesis is ideal. The questions that always arise when individual cusps are replaced are: (1) Will the prosthetic cusps be competent immediately and remain so for a period of significantly long duration? (2) Will the continuous movements cause fatigue and break the plastic material? (3) Will tissue ingrowth cause thickening with decreased mobility, calcification, and progressive stenosis? The aim of this paper is to report the one year follow-up of a group of patients who underwent aortic valve replacement with individual cusps of Teflon, designed by Bahnson, or with a total prosthesis of Teflon, as designed by Muller. MATERIAL
Thirteen patients were accepted for aortic valve replacement; the youngest was 20 and the oldest 50 years of age. One patient had pure ealcific aortic stenosis, 3 had pure aortic insufficiency, and the remaining 9 had a combination of stenosis and insufficiency. The largest heart was 810 ml. per square meter of body surface area. The only heart with normal size (400 ml. per square meter) was in a patient with ealcific aortic stenosis and insufficiency with a peak systolic pressure gradient of 107 mm. Hg over the aortic valve. In 7 cases, calcifications were visible on tomography. SURGICAL T E C H N I Q U E
The heart-lung machine was started with a very small flow, usually 1 L. per minute for the first minutes until a clamp was placed on the ascending aorta. The perfusion rate was then increased to a calculated value of 2.2 L. per square meter of body surface area. From a side branch of the arterial line, blood was pumped through a catheter and through a special cannula held in the coronary ostia. The left coronary artery was perfused during almost the entire time the aortotomy was open. The right coronary artery was also perfused. The longest time for left coronary artery perfusion was 104 minutes and for right coronary perfusion was 29 minutes. The average perfusion time was 100 minutes (range, 61 to 146 minutes). F r o m t h e U n i v e r s i t y H o s p i t a l , U p p s a l a , Sweden. Received for p u b l i c a t i o n A u g . 23, 1962.
635
B J 6 B K , CULLHED, L O D I N
636
J. Thoracic and Cardiovas. Surg. TABLE I .
CASE
AGE
DIAGNOSIS
1 2 3 4
29 41 43 44
AS AS + A I AI AS + A I
5 6 7 8
20 24 50 39
AI AI AI AI
RHEUMATIC FEVER
CALCIFICATIONS (TOMOGRAM)
CLINICAL AND
HEART SIZE ( M L . / M . 2 BSA) EOLLOW-UP
-
+ + 0 +
/ . One Prosthetic Cusp 540 670 590 520 580 870 530 480
+
0 0 + 0
II. Three Prosthetic Cusps 540 445 650 830 570 460 640 475
0
III. Total Valve 650
+ +
-
+
41 9 AI •Pressures taken one year after operation. tAt operation.
Prosthesis 690
PRIMARY RESULT
In the first 4 cases in which only one aortic cusp was replaced, all patients survived. In 3 of them (Cases 1, 2, and 4) there was calcine aortic stenosis, combined with insufficiency in 2 cases. The primary result was good in these 3 cases. In the fourth case (Case 3), there was no calcification. The patient survived with remaining aortic insufficiency. Nine patients had removal of all cusps. Eight patients had replacement with individual cusps. Of these 8 patients, 4 died; one from remaining aortic insufficiency, one from infection one month after the operation, and one patient 12 days after an unsatisfactory repair in a very distorted and narrow calcific aortic ring. The fourth patient was a 50-year-old man having an aortic pressure gradient of 107 mm. Hg who first made a satisfactory recovery but died suddenly two weeks after operation when he was walking around in the ward. At autopsy the local result was excellent. The remaining 4 patients who had all three cusps replaced showed a good primary result. One patient had a dilated aortic ring with bicuspid aortic valves where both cusps were prolapsing. Replacement was performed with a Muller prosthesis, in which three Teflon cusps are mounted on a Teflon frame. The patient made a good recovery. TWO YEAR FOLLOW-UP
The pertinent clinical and hemodynamic findings at the two year follow-up are summarized in Table I. A. One Cusp Replaced.— In this group of 4 patients, 2 were improved (Cases 2 and 3) and 2 were not (Cases 1 and 4). CASE 1.—A 29-year-old man with calcific aortic stenosis and a maximal pressure gradient of 80 mm. H g had the noncoronary cusp replaced by a 30 mm. Teflon cusp. After operation the aortic gradient was abolished and the primary result was good. However, during the
5
Vol. 45, N o May, 1963
637
AORTIC VALVE P R O S T H E S I S
HEMODYNAMIC OBSERVATIONS AORTOGRAPHY DEGREE REGURG. BEFORE
|
LV P R E S S U R E ( R E S T ) *
FOLLOW-UP
BEFORE
| FOLLOW-UP
(0) ++ +++ ++
+++ + +++ ++
170/5 225/23 150/15 247/15
144/20
+++ +++ +++ +++
+ +++ 0 (+)
110/lOt 181/10 158/17t 135/12
171/18 130/21
+++
+++
165/10
P E A K SYSTOLIC GRADIENT ( R E S T ) BEFORE
FOLLOW-UP
IMPROVED
80 60 0 109
28 11 18
No Yes Yes? No
131/4
0 0 0 0
9 7 30 16
Yes No Yes Yes
195/10
0
9
141/15 198/22
No
following year the heart enlarged and a diastolic murmur became obvious. There was an aortic gradient of 70 mm. H g with a significant aortic insufficiency demonstrated by aortography. Thirteen months after the first operation, another operation was performed. The Teflon cusp showed a central rupture down to its base. I t was thickened, had decreased mobility, and seemed to be calcified. However, crystalography demonstrated protein but no calcium (Figs. 1 and 2 ) . The Teflon cusp as well as the calcified right and left cusps were removed and a ball valve prosthesis, according to Starr, was sutured in place. The patient made an uneventful recovery and is, after another year, in excellent condition. CASE 2.—A 41-year-old man had calcific aortic stenosis as well as a severe aortic insufficiency. The calcific left aortic cusp was excised and substituted by one 30 mm. Teflon cusp. The right and noncoronary cusps were fused together into one rigid calcific rock and were left in place. At the end of operation there only remained a 10 mm. H g gradient over the aortic ostium and the aortic insufficiency was completely abolished. After two years, the heart had diminished in size from 590 to 520 ml. per square meter. CASE 3.—A 43-year-old man with a history of rheumatic fever was found to have a combination of aortic stenosis and insufficiency. The fused commissure between the right and the noncoronary cusps was opened and one 42 mm. Teflon cusp replaced the noncoronary cusp. I t was noted at the time of operation that it would be difficult to obtain a complete competence without the use of a total prosthesis. A diastolic murmur remained and when the patient left the hospital it was obvious that he had a significant residual aortic insufficiency. As he feels improved, re-operation has been postponed. CASE 4.—A 45-year-old man with calcific aortic stenosis and insufficiency had the noncoronary cusp replaced by a 30 mm. Teflon cusp. An aortic gradient of 109 mm. H g was reduced to 18 mm. H g and the heart diminished in size, although the same degree of insufficiency remained after the operation. The patient is not subjectively improved, probably because of coronary artery disease.
B. AU Cusps Replaced.— CASE 5.—A 20-year-old man had a significant aortic insufficiency and a large heart. Three prolapsing cusps were replaced with three isolated Teflon cusps. After two years, the heart had diminished in size from 540 ml. to 445 ml. per square meter. There was a minimal residual insufficiency (at aortography a thin contrast leakage was observed immediately beneath the valvular area) and a resting aortic gradient of 21 mm. Hg, which, however, rose to 53 mm. H g on a work load of 600 kilograms per meter per minute (Figs. 3^4 and 3 B ) .
638
BJoRK, CULLHEI), LODIN
.1. Thoracic and Cardiovas. Surg.
Pig. 1.—Case 1. The aortic (A) and left ventricular view (B) of the ruptured Teflon cusp removed after 13 months. Note the thickened edges along the rupture. The base of the cusp was firmly healed in place.
Fig. 2.- -A roentgenogram of the removed Teflon cusp demonstrates the thickening along the rupture and the base of the cusp.
Vol. 45, No. 5 May, 1963
AORTIC VALVE P R O S T H E S I S
639
CASE 6.—A 25-year-old man with aortic insufficiency had an increase in heart size from 450 ml. to 650 ml. per square meter during 5 years. Three prolapsing cusps were found at operation and they were replaced by 3 Teflon cusps. Primary healing was uneventful and the patient left the hospital with competent aortic cusps. At follow-up, a free insufficiency was found and the heart was further dilated. Re-operation was advised but the patient did not accept. He died 2 months later. The Teflon cusps were found fragmented in the edges and there was a central hole, as well as dislocation, at the base of one of the cusps (Fig. 4 ) . The main insufficiency was caused by the dislocation at the base of one cusp.
Fig. 3.—Case 5. Postoperative examination (thoracic aortography). The valve prostheses show reduced mobility, especially the left and right, valves with formation of a dome (->) and a Jet (A). Slight incompetence in diastole (JB).
B J 6 R K , CULLHED, LODIN
640
J. Thoracic and Cardiovas. Surg.
CASE 7.—A 50-year-old man had calcific aortic stenosis with a gradient of 80 mm. Hg, which was abolished by transventricular dilatation. An aortic insufficiency present before operation was increased. The patient was improved for 1% year, but 2 years after the first operation his condition deteriorated and he was re-operated upon. The right aortic cusp was ruptured. Three isolated Teflon cusps were sutured in place after excision of all three aortic cusps. At follow-up, the heart had diminished from 530 ml. to 460 ml. per square meter. The resting aortic gradient was 27 mm. H g and the gradient at a work load of 600 kilograms per meter per minute did not increase to more than 31 mm. Hg. The insufficiency was completely abolished and the patient was free of symptoms (Figs. 5, A, B, and C).
Fig. 4.—Case 6. Autopsy specimen of a Teflon cusp after one year. The cusp was dislocated at its base with free insufficiency. Note fragmentation of Teflon edges. CASE 8.—A 39-year-old man, who had had rheumatic fever at the age of 11, had aortic regurgitation with a dilated heart. At operation three prolapsing cusps were excised and replaced with three Teflon cusps. At follow-up a perfect result was found with reduction in heart size from 640 ml. to 475 ml. per square meter. A resting aortic gradient of 16 mm. H g was found. The aortography showed thickened but completely competent aortic cusps (Figs. 6A, B, and C). CASE 9.—A 41-year-old man had aortic insufficiency with a large heart—650 ml. per square meter. At operation a bicuspid aortic orifice was found and the two prolapsing cusps were excised. In this case it was necessary to use a total valve prosthesis and the one described by Muller was used. At one year follow-up the heart had not diminished in size, but the insufficiency was completely abolished and no gradient was found. However, at a 1% year follow-up, a free aortic regurgitation had re-appeared. At re-operation, this was found to be due to a rather small distal perforation in one of the 3 cusps mounted on a Teflon frame. The patient died one week after re-operation. DISCUSSION
This two year follow-up has showed that in the majority of cases a good functional result can be obtained. However, tissue ingrowth and deposition of protein and fibrin has caused a significant thickening of the Teflon cusps.
Vol.45, No. 5 May, 1963
AORTIC VALVE PROSTHESIS
641
Fig. 5.—Case 7. Systole (A). Diastole (B-C). Postoperative examination. Thoracic aortography. The valve prostheses show reduced mobility with backward directed jet (->) in systole. The cusps, especially the noncoronary one, are thick and with irregular contours. Where the base of the noncoronary and right valve prosthesis were sutured together, there is a pea-sized contrast defect (C) (parietal thrombus?). No incompetence.
642
B.T5BK, CULT.HEB, LODTN
J. Thoracic and Cardiovas. Surg.
Fig. 6.—Case 8. A, Preoperative examination. Thoracic aortography. Extreme aortic insufficiency.
This thickening will diminish the mobility of the cusp and cause some degree of stenosis, so far only with a small gradient. However, in one case (Case 5) a gradient of 21 mm. Hg at rest and 53 mm. Hg on exercise was found. It is thus obvious that the stiffening is pronounced enough to cause a slight but definite gradient over the aortic orifice in most cases. Angiocardiographic studies have furthermore demonstrated this decreased mobility, although in the majority of cases there was a complete competence during diastole. It was found that in systole the cusps opened only partly. In some cases the thickening was clearly visible and irregularities on the prosthetic cusps suggested ingrowth of tissue and deposits of fibrin. The ability to obtain completely competent valves is most encouraging. However, the decreased mobility, as demonstrated by angiocardiography as well as with pressure measurements, is of sufficient importance to question the
Vol. 45, No. 5 May, 1963
AORTIC VALVE PROSTHESIS
643
Fig. 6.—B and G, Postoperative examination. The valve prostheses (<—► ) are slightly thickened but show good mobility. (B) Systole; (C) diastole. No insufficiency visible.
644
BJORK, CULLHED,
LOD1N
J. Thoracic and Cardiovas. Surg.
advisability of using this material, as, already after one year, a slight but definite stenosis has been observed, with decreased mobility and irregularities of the cusps. I t is probable that these changes may progress to produce more severe stenosis in the longer follow-up. The most important observation, however, is that a thickened Teflon cusp ruptured down to its base and caused severe insufficiency. It can naturally be argued that in this case a monocusp was used which was constantly beating against the calcific aortic cusps left in place. It is, however, most probable that a thickened cusp will more easily wear out and break the plastic material. This has been proved in 3 cases. The question arises: Will more such ruptures occur as time goes by? I t is the obvious conclusion that aortic valve prostheses of Teflon permit tissue ingrowth, do not maintain an ideal function, and may rupture after one year. Therefore, a more satisfactory material must be sought for aortic valve replacement. We will continue to follow our cases but after this experience we do not at present use Teflon cusps but are using a ball valve prosthesis, first advocated by Harken and then perfected by Starr and manufactured by Edwards. AVe only advise total aortic valve replacement in patients who are in a late and severe stage of their disease. SUMMARY
A follow-up study with angiocardiography and left heart catheterization of patients who have had the aortic valve replaced by a prosthesis with Teflon cusps has been presented. Due to tissue ingrowth and thickening of the Teflon cusps, a decreased mobility has been noted. These irregularities and thickening of the cusps have caused slight but definite aortic stenosis, demonstrated as well by angiocardiography as by pressure measurements. In 3 cases the thickened Teflon aortic cusp ruptured and had to be replaced by a ball valve prosthesis in 2 cases. REFERENCES
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