The Björk-Shiley tilting disc valve in isolated mitral lesions

Evaluation of obstructive characteristics of mitral disc valve implants with ultrasound doppler techniques

Ten adult patients with mitral disc valve implants have been examined on the catheterization table. Non-invasive ultrasound Doppler data, pulmonary artery wedge pressure and left ventricular pressure were recorded simultaneously. The cardiac output was determined with the direct Fick method. The effective valve area was taken as a measure of the flow obstruction in the disc valve implants. This area was calculated from the ultrasound data and the cardiac output as well as from the manometric data and the cardiac output. The resulting two sets of areas demonstrated a linear correlation coefficient of 0.86. The effective valve areas calculated from the ultrasound data were reasonable when compared with the results of in vitro studies of disc valve performance and demonstrated good agreement with the findings of other investigators.

Obstructic characteristics of Björk-Shiley, Hancock, and Lillehei-Kaster prosthetic mitral valves in the immediate postoperative period

The flow obstruction in mitral valve implants was studied in the immediate postoperative period in 19 patients with Björk-Shiley, Hancock, or Lillehi-Kaster prosthetic mitral valves. The effective valve area (Ae) was used as a measure of the flow obstruction. The blood velocity in the implants was estimated with a non-invasive ultrasound Doppler system. The cardiac output was determined with an indwelling thermodilution catheter. The collected data allowed the determination of Ae. Multiple determinations of Ae, at various cardiac outputs and pulse rate were generally performed in each patient during the first 2--3 postoperative days. The investigation demonstrated that the method employed was useful for the study of mitral implant performance. The obtained values of Ae demonstrated that the flow obstruction in presthetic mitral valve implants is frequently considerable.

Exercise evaluation of prosthetic heart valves by Doppler echocardiography: comparison with catheterization studies

Although valve replacement remains the cornerstone of treatment for critical heart valve dysfunction, problems including thromboembolism, infection, and primary failure of the prosthesis remain. Resting studies of valve hemodynamics are sometimes insufficient to reveal valve dysfunction. Early studies using cardiac catheterization focused on changes in prosthetic function seen with various types of exercise or drug-induced stress. These studies suffered from an inability to adequately stress catheterized patients and were cumbersome to the patient and the investigator. With the introduction of Doppler echocardiography, however, studies could be performed after significant exercise with low risk and increased ease. Using echocardiography, reports of exercise-induced changes in aortic and mitral valve hemodynamics have appeared. Over 600 patients have been studied using Doppler echocardiography. In the aortic position, all prostheses studied have a mild peak instantaneous gradient (18-26 mmHg) at rest, which increases with exercise (35-63 mmHg). No significant differences between the four models of mechanical prostheses studied are found. The gradients achieved with exercise do not appear to be related to the heart rate achieved or duration of exercise. Smaller prostheses are associated with larger gradients; however, the correlation was not strong. All mitral valve prostheses studied are also mildly stenotic at rest (range of mean gradients 2.3-7.1 mmHg) and become moderately stenotic with exercise (range 5.1-16.5). Although the lowest gradients are seen with St. Jude Medical and Medtronic Hall prostheses, their gradients are not significantly less than with other valves.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Doppler-obtained velocity curves in functional evaluation of mechanical prosthetic valves in the mitral and aortic positions

A total of 145 patients with 160 mechanical prostheses of the Björk-Shiley or Starr-Edwards type (15 with double mitral plus aortic valves) underwent clinical and Doppler echocardiography analysis. In the mitral position (85 valves) 10 patients with valve-related symptoms, calculated prosthetic area less than or equal to 1 cm2, or mean transprosthetic gradient greater than 10 mm Hg by Doppler echocardiography were predefined as abnormal. Seven patients had operations, and prosthetic obstruction was confirmed in all. All patients had higher pulmonary pressures (p less than 0.001) before valve replacement. Clinical presentation was variable; however, all those with proved prosthetic thrombosis had a fulminant course and distinctive velocity curves on Doppler. In the 75 patients predefined as normal, calculated valve area (2.3 +/- 0.6 cm2, mean +/- SD, range 1.3 to 3.7 cm2) and mean gradient (4.9 +/- 1.7 mm Hg, range 1.5 to 9.5 mm Hg) were widely spread and were independent of prosthetic size greater than or equal to 27 mm. Clinically 37 of 75 patients were moderately to severely limited. Mean gradient above 5 mm Hg was associated with a higher incidence of chronic atrial fibrillation (p less than 0.05), significant tricuspid regurgitation, failure of the right side of the heart, and significant functional limitation (p less than 0.02 for all). In the aortic position (75 valves) peak gradients were 28.2 +/- 15 mm Hg (8 to 80 mm Hg). Mean gradients were 18 +/- 9.6 mm Hg (6.5 to 46.5 mm Hg). Averaged gradients derived from the average of peak and late systolic gradients were 22.4 +/- 12.7 mm Hg (6 to 62 mm Hg). In all five abnormal patients (two with endocarditis and three with hemodynamic decompensation) but also in 18 of 70 clinically normal valves, peak gradients were greater than or equal to 36 mm Hg (ranges 36 to 65 mm Hg in both). Gradients were unrelated to symptoms or to the duration of the valve in situ (3 weeks to 20 years). Gradients correlated with prosthetic size (r = 0.57) and were higher (p less than 0.001) across small (19 to 23 mm) versus large (25 to 31 mm) valves. Regurgitation was present in 40% of the mitral prostheses. It was detected in 32% of the mitral prostheses defined as normal and was estimated as mild in most. Aortic regurgitation was present in all five abnormal aortic prostheses, significant in four, and in 26 of the valves (37%) defined as normal, significant in two.(ABSTRACT TRUNCATED AT 400 WORDS)

Validation of continuous-wave Doppler echocardiographic measurements of mitral and tricuspid prosthetic valve gradients: a simultaneous Doppler-catheter study

For patients with stenotic native valves, the modified Bernoulli equation (delta P = 4V2) may be applied to Doppler-measured transvalvular velocities to yield an accurate estimate of transvalvular gradients. Although it would be useful if the same approach could be used for those with stenotic prosthetic valves, no previous study has validated the Doppler technique in this setting. We therefore recorded simultaneous continuous-wave Doppler flow profiles and transvalvular manometric gradients in 12 catheterized patients in whom all atrial and ventricular pressures were directly measured (transseptal left atrial catheterization and transthoracic ventricular puncture were performed where necessary). A total of 13 prostheses were studied: 11 mitral (seven porcine, three Starr-Edwards, and one Björk-Shiley) and two tricuspid (one porcine and one Björk-Shiley). The Doppler-determined mean gradient was calculated as the mean of the instantaneous gradients (delta P = 4V2) at 10 msec intervals throughout diastole. The correlation of simultaneous Doppler (DMG) and manometric mean gradients (MG) for the whole group (n = 13) demonstrated a highly significant relationship (MG = 1.07 DMG + 0.28; r = .96, p = .0001). The correlation was equally good for porcine valves alone (n = 8) (MG = 1.06 DMG + 0.55; r = .96, p = .001) and for mechanical valves alone (n = 5) (MG = 1.06 DMG - 0.04; r = .93, p = .02). In a subset of patients without regurgitation (n = 8), prosthetic valve areas were estimated by two Doppler methods originally described by Holen and Hatle, as well as by the invasive Gorlin method. As expected from theoretical considerations, a close correlation was not demonstrated between results of the Gorlin method and those of either Hatle's Doppler method (r = .65, fp = NS) or Holen's method (r = .14, p = NS). Comparison of the results of the two Doppler methods yielded a somewhat closer correlation (r = .73, p less than or equal to .05). These results suggest that in patients with disk-occluder, ball-occluder, and porcine prosthetic valves, Doppler estimates of transvalvular gradients are virtually identical to those obtained invasively.

Doppler echocardiographic evaluation of Hancock and Björk-Shiley prosthetic values

Doppler echocardiographic characteristics of normally functioning Hancock and Björk-Shiley prostheses in the mitral and aortic positions were studied in 50 patients whose valvular function was considered normal by clinical evaluation. Doppler studies were also performed in 46 patients with suspected malfunction of Hancock and Björk-Shiley valves and who subsequently underwent cardiac catheterization. Mean gradients were estimated for both mitral and aortic valve prostheses and valve area was calculated for the mitral prostheses. Doppler prosthetic mitral valve gradient and valve area showed good correlation with values obtained with cardiac catheterization (r = 0.93 and 0.97, respectively) for both types of prosthetic valves. The correlation coefficient (r = 0.93) for mean prosthetic aortic valve gradient was also good, although Doppler echocardiography overestimated the mean gradient at lower degrees of obstruction. Regurgitation of Hancock and Björk-Shiley prostheses in the mitral and aortic positions was correctly diagnosed. These results suggest that Doppler echocardiography is a reliable method for the characterization of normal and abnormal prosthetic valve function.

Thrombotic obstruction of Bjork-Shiley valves--diagnostic and surgical considerations

We have evaluated 12 patients with thrombotic obstruction of the Bjork-Shiley valve since 1975, 11 in the mitral and 1 in the aortic position. During this period 442 patients with 303 mitral (181 plano-convex and 122 convexo-concave) and 205 aortic (112 plano-convex and 93 convexo-concave) Bjork-Shiley valves were available for follow-up. The incidence of thrombosis for the plano-convex model was 1.06% per patient year for the mitral position and 0.19% per patient year for the aortic position. The new convexo-concave model has brought down the incidence to 0.78% per patient year for the mitral (P less than 0.01) and 0% per patient year for the aortic valve. The onset of symptoms was acute (less than 15 days) in 41.7% and subacute (greater than 15 days) in 58.3% patients. All patients presented with pulmonary edema. Evidence of inadequate anticoagulation was present in only 3 (25%) patients. Reduction of prosthetic sounds and appearance of a new murmur was highly suggestive of valve thrombosis. Echocardiography and cinefluoroscopy was very useful for the instant recognition of this condition and had obviated the need for cardiac catheterisation in the last 6 patients. Emergency surgery was obligatory in all. Thrombectomy alone was successful in 9 patients. Three patients required replacement of the prosthesis. There was one operative death (mortality 8.3%). The long-term follow-up of these patients (3-82 months, mean 34 months) is excellent. We conclude that thrombotic obstruction of the Bjork-Shiley valve is often not related to inadequate anticoagulation, and more than half of the patients do not present with abrupt onset of symptoms. The convexo-concave model has significantly reduced this problem. Emergency surgery with thrombectomy is the procedure of choice for clotted prostheses.

Mechanical heart valves in children

Longterm follow-up of 17 children, who consecutively underwent replacement of one cardiac valve with the Björk-Shiley prosthesis, is presented. The children's mean age was 8 years (range 4-12 years) and body weight 23.5 kg (range 15.0-38.4 kg) at the time of surgery 1970-80. Nine of the 17 operations (53%) were second-stage cardiac surgery. The operations comprised 2 aortic and 7 mitral valve replacements, 2 implantations of prosthesis in aortoventricular plasties (Konno's operation), 4 in the functional mitral orifice of transpositions (3 congenitally corrected and one operated on a.m. Mustard) and 2 valved conduits included in the repair of complex malformations. Two deaths were associated with surgery, but were not related to the valve prosthesis per se. One patient died 37 months postoperatively, due to mechanical valve failure (early and late mortality 12% and 6%, respectively). All survivors were followed at least two years, 9 were followed at least 5 years and 6 at least 10 years (mean 7.7 years). Anticoagulation was maintained without pertinent problems. There was one thromboembolic episode (0.87%/patient year). Two patients were reoperated because of "outgrown prosthesis" after 8 and 11 1/2 years. Morbidity otherwise was low and 9 patients (53%) had no complications at all. We conclude that the mechanical valve is a suitable substitute for a seriously diseased cardiac valve in childhood. However, if valve replacement is performed in early life, the later need of exchange of the outgrown prosthesis must be faced.

Prosthetic heart valves: a review

There are a number of difficulties inherent in the analysis of such a large and diverse quantity of data. In a substantial number of clinical trials, there is no significant effort made to evaluate prosthetic performance as a function of preoperative cardiac anatomy. Hemodynamics have not been systematically studied in relation to preexisting left ventricular size, shape, or configuration, mitral annular orientation, or left atrial size. Postoperative anticoagulation protocols vary from one institution to another and occasionally within study groups themselves. Less tangible variables such as alteration in surgical technique over time and differential familiarity of cardiovascular surgeons with the prostheses employed are chronic problems in any study of this sort. Perhaps the greatest variable in evaluating the postoperative performance of valvular prostheses over the past 20 yr is the radical improvement in techniques of intraoperative myocardial preservation. Notwithstanding, comparisons are possible within the confines of certain criteria. The caged ball value remains in use after 20 years of clinical experience. It has sustained the greatest number of modifications, probably because it has been the most extensively studied. Hemodynamics are adequate although its centrally obstructed design is responsible for increased turbulence, hemolysis, and neointimal proliferation, particularly in the aortic position. The device has been shown to be durable with virtually no reports of ball variance since the alteration of the silicone curing procedure in 1965. Thromboembolic rates are acceptable in the anticoagulated patient while prosthetic thrombosis is not a grave threat in the non-close clearance device. Incidence of endocarditis is not particularly different from that associated with all nonbioprosthetic valves, although there is a much greater published volume of clinical experience concerning recognition and treatment of late prosthetic valve endocarditis in patients with caged ball valves than there is for any other replacement device. Perhaps the most serious disadvantage to caged ball design is its size. Its large spatial requirements have led to anatomic complications in patients with small aortic roots, isolated mitral stenosis, left ventricular hypertrophy, and double valve replacement, among others. Nevertheless, this is still the valve of choice in some centers.(ABSTRACT TRUNCATED AT 400 WORDS)

Echocardiographic assessment of the Hall Kaster mitral prosthesis

To study the effect of the Hall Kaster prosthesis on left ventricular filling characteristics after mitral valve replacement, postoperative M-mode echocardiograms of the left ventricle from sixteen patients were digitized to determine the peak rate of dimension (D) increase of the left ventricle during diastole (peak dD/dt) and the rapid filling period (RFP). These were compared with fourteen normal controls, thirty patients with Starr Edwards and thirty patients with Bjork Shiley mitral prosthesis. Results suggest that the Hall Kaster mitral prosthesis is less obstructive than either the Starr Edwards or the Bjork Shiley prosthesis, and tends to approximate the normal mitral valve.

Thrombolytic therapy for a thrombosed Bjork-Shiley tricuspid valve prosthesis

A 67-year-old mand in whom mitral and tricuspid Bjork-Shiley tilting disc prostheses had been implanted 68 months previously presented with thrombotic obstruction of his tricuspid prosthesis. Initial cardiac catheterization demonstrated a significant transprosthetic tricuspid diastolic gradient (9.5 mmHg) with a calculated prosthetic valve orifice area (0.62 cm2) indicating a critical degree of stenosis. The resting cardiac index was markedly reduced (1.5 l/m2/min). Following an intravenous infusion of streptokinase for 66 hours, repeat cardiac catheterization revealed a 50% reduction in transprosthetic diastolic gradient across the tricuspid valve (4.7 mmHg), a greater than fourfold increase in prosthetic valve orifice area (2.87 cm2) with a normal resting cardiac index (3.1 l/m2/min).

The optimal opening angle of the Björk-Shiley tilting disc valve prosthesis

The basic design of the Björk-Shiley tilting disc valve prosthesis has not been changed during the 12 years that it has been used in clinical practice for 2578 valve replacements at Karolinska Sjukhuset, Stockholm. A 10-year survival rate of 65%, including operative mortality, was achieved in the first 125 patients who underwent aortic valve replacement. Certain improvements have been made, however, with the introduction of a convexo-concave pyrolytic carbon disc and an integral inflow strut. In order to optimize valve function, the opening angle of the disc was increased to 70 degrees, thereby decreasing disc rotating velocity significantly at opening impact and with less strut wear. Diminished downstream turbulence is encountered with the 70 degree opening angle. There is nothing to be gained at present by widening the opening angle still further, as an increased pulsatile regurgitation would more than outweigh the advantages obtained by the reduced gradient.

Physical training after heart valve replacement

A controlled trial was undertaken to examine the efficacy of physical training in patients recovering from the replacement of a single heart valve. Patients were allocated to a test or control group two weeks after operation. Each patient performed a submaximal exercise test at entry, and 12 and 24 weeks after this test. The Canadian Air Force exercise programme was undertaken by the test group, while the control group continued normal activities for the 24 weeks between the first and last exercise group. A regression line of submaximal heart rate on oxygen consumption was calculated from the data of each exercise test in each patient. Alterations in this line were used as an "index" of changes in "cardiorespiratory fitness". The individual results showed a consistent improvement in "cardiorespiratory fitness" over the first 12 weeks in both groups. Only patients in the test group continued to improve between 12 and 24 weeks. Thus the exercise programme modified the recovery of "cardiorespiratory fitness" after operation. Results in patients who developed clinical complications, and were excluded from the trial, predicted a deteriorating clinical condition. This finding suggested that sequential exercise tests are of value after cardiac surgery.

Porcine valves

To date, the glutaraldehyde porcine aortic valve xenograft has proved a good choice for valve replacement in both the aortic and mitral positions. Late thromboembolisms in the absence of long-term anticoagulation is virtually nonexistent in aortic valve replacement and very low in mitral valve replacement patients without a predisposing history. The hemodynamic performance of the porcine xenograft is adequate and comparable to that of mechanical prostheses. The potential for improved hydrodynamic function, particularly of very small sized valves, is great and already being realized. In spite of over 8 yr of xenograft experience, long-term durability remains the primary concern. Histologic study suggests that these valves undergo progressive postimplantation morphological alteration. However, to date, the incidence of tissue failure is very low. Although detailed reports of long-term valve series are surprisingly few, at present, there is no valve replacement device with a 10-yr experience proven structural integrity and a negligible incidence of valve-related morbidity. It will be 3-4 yr before a significant number of porcine xenograft patients either reach this point or experience valve failure. While this review of the valve literature does not permit a statistical comparison of valve types, we feel that it does allow us to attempt a general projection. On the basis of combined survival and valve-related complication rates, at 4 yr, the porcine xenograft appears to be a better choice than the mechanical prosthesis. Excessive tissue failure during the next 3-4 yr might reverse this opinion. However, even if an increase in valve failure does occur, the advantage of noncatastrophic disfunction and decreased valve-related complications may balance the risk of reoperative morbidity and mortality and continue to favor the porcine exnograft. Thus we could speculate that: (1) The tissue valve would be the valve of choice if (A) durability of 10 yr or more is proven, and valve complications with the xenograft remain as presently reported; (B) the incidence of valve complications with the mechanical prostheses at 10-yr follow-up continues to increase. (2) Mechanical prostheses would be the valves of choice if (A) xenograft valve failure is greater than 20% at 10 yr of follow-up; (B) the incidence of valve complications with the mechanical prostheses remains unchanged. (3) The choice of xenograft versus mechanical prosthesis will remain an open issue if valve failure and related complications with both types of device remain below 20% at 10-yr follow-up...

Echo-phonocardiographic evaluation of obstruction of prosthetic mitral valve

Echo-phonocardiograms of 64 patients with multiple types of prosthetic mitral valves (PMV) were evaluated. Six patients demonstrated findings suggesting valve obstruction: four had surgical confirmation of prosthetic obstruction, one reduced cardiac output and pulmonary hypertension but no prosthetic dysfunction at surgery, and one is asymptomatic. Three of four patients with confirmed obstruction had variable second sound to opening click intervals (A2-MO) with interrupted disc opening; two had interrupted disc closure with split closing clicks and three of four had reduced diastolic closure rate. In 58 clinically well patients with PMV, cycle-to-cycle A2-MO varied little: 0-10 msec in sinus rhythm and 10-25 msec in atrial fibrillation. Diastolic closure rates of five different types of PMV were similar: 21.6 mm/sec, (range 14-49). No patient had interrupted opening, closing or multiple closing clicks. Thus, delayed PMV opening or closure, altered A2-MO interval and double closing clicks are highly useful in detecting patients with obstruction of a variety of mitral prostheses.

Haemodynamic findings after insertion of the Lillehei-Kaster valve in the mitral ostium

Clinical deterioration after insertion of prosthetic mitral valves may be caused by myocardial failure or valve dysfunction or a combination of both. The need for a method to decide which is predominantly causative is obvious. This study describes the haemodynamic findings with special reference to prosthesis rheology among 13 patients with lillehei-Kaster valves in the mitral ostium. Three patients were re-operated on because clinical signs of valvular dysfunction. Our investigation indicates that stroke volumes of less than 35 ml were useful in predicting valve dysfunction and that pulmonary wedge and mean arterial pressure at rest were significantly increased in this group of patients. It is advocated that such haemodynamic findings should lead to further evaluation of valve gradient and valve flow.

Clinical and haemodynamic observations after combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis. Early and late results in 25 patients

Combined mitral and aortic valve replacement with the Björk-Shiley tilting disc valve (pyrolite) was performed in 25 unselected patients characterized by markedly impaired functional capacity, hypokinetic central circulation and cardiomegaly before operation. Surgery was performed during extracorporeal circulation with deep hypothermia. The mitral valve was replaced first in all cases. There were no intra-operative deaths, but 2 patients died while still in hospital (8.0%). One patient died 2 months postoperatively due to progressive heart failure. The remaining patients--with the exception of one who had died of cancer of the ovary--were re-examined in average 28.7 (18-40) months postoperatively. Most patients had improved symptomatically and were in functional classes I-II (N.Y.H.A.). The haemodynamic findings indicated restoration to normal resting values of cardiac output, pulmonary artery pressure and pulmonary vascular resistance, but with an increase in left ventricular end-diastolic pressure (LVEDP). The mean diastolic gradient across the mitral prosthesis varied from 0 to 11 mmHg, while simultaneous pressure recordings from the left ventricle and the aorta, with one exception, disclosed no systolic pressure gradients (peak) across the aortic valve. Postoperative arterial thrombo-embolic complications occurred in 2 patients, resulting in only minor neurological sequelae.

Anticoagulants and the Björk-Shiley prosthesis. Experience of 390 patients

From September 1972 to January 1975, 390 patients underwent valve replacement using the Björk-Shiley tilting disc prosthesis. For the group as a whole hospital mortality was 13.3 per cent and was lowest in those undergoing isolated mitral or aortic valve replacement (5.3 and 9.4%, respectively). Available for follow-up were 209 patients of whom 123 were maintained on dipyridamole and 96 on warfarin. Thromboembolic complications were significantly (P less than 0.01) commoner in the dipyridamole (28 of 123, 22%) than warfarin (6 of 86, 7%) treated group. In the dipyridamole treated group the incidence of thromboembolic complications was similar whichever valve was replaced and thromboembolic complications were responsible for 14 of the 28 late deaths. In the warfarin treated group thromboembolic complications only occurred in patients with a mitral prosthesis. Anticoagulation is indicated for all patients with this prosthesis wherever inserted.

The improved Björk-Shiley tilting disc valve prosthesis

The Björk-Shiley valve has been improved in three respects: (1) Increased strength by making the inlet strut an integral part of the orifice ring and doubling its cross-section area; (2) Improved hydrodynamics; (3) Elimination of the area of stagnant and low flow behind the disc. By utilizing a convexo-concave disc and by moving the pivot point downstream, the disc in open position is moved further out of the orifice ring. The flow through the smaller hole is thus increased by 40%. A significant clearance is obtained between the disc and the valve ring in open position. 234 of these valves have been inserted and followed-up for a maximum period of two years with excellent results.

Clinical and haemodynamic results following mitral valve replacement with the new Lillehei-Kaster pivoting disc valve prosthesis

Thirty-four patients were re-examined 12-24 months after mitral valve replacement with the Lillehei-Kaster pivoting disc valve prosthesis. There was an improvement of the kinetics with a significant decrease in arteriovenous oxygen difference compared with oxygen consumption. Cardiac output and stroke volume remained abnormally low, not differing significantly from pre-operative values. Resting pulmonary wedge pressure, pulmonary arterial pressure and pulmonary vascular resistance decreased significantly after operation. Mean values for these parameters remained slightly above normal. Exercise produced a rise in pulmonary wedge pressure, which could be explained partly by a simultaneous deterioration of the left ventricular function, as indicated by high end-diastolic pressures, and partly by a degree of obstruction to the foreward flow at the mitral valve itself. The rise in pulmonary wedge pressures led in turn to increased pulmonary arterial pressure, the latter being aggravated in some patients by a rise in pulmonary vascular resistance. Cardiac output increased during exercise, but usually to a lesser extent than was anticipated from the increase in oxygen consumption. The changes in cardiac output during exercise were due to an increase in heart rate, while stroke volume remained unchanged. The mean diastolic pressure difference across the prosthesis was 8.6 mmHg at rest and 12.7 mmHg during exercise. Subjective improvement and reduction in heart volume, as noted in the present series, corroborated the benificial effect of the operative procedure. The valve were all competent, as judged by cinéangiography, except in a few patients, in whom a small valvular or paravalvular leakage was seen. No thrombo-embolic episodes were recorded during the follow-up period.

Management of the patient with a prosthetic heart valve

Approximately 20,000 heart valve prostheses are inserted yearly in the United States. Even after successful heart operations, the patients who receive them cannot be regarded as healthy individuals but are a special group with special problems who need close medical attention for the rest of their lives. They are susceptible to many unusual complications because of their implanted foreign body, and it is a challenge to all physicians in contact with them to be aware of their peculiar problems in order to prevent complications if possible and to treat them immediately if they occur. General therapy, surgical complications, infection, and mechanical problems are reviewed, with means for management outlined. These difficulties can be dealt with only by careful follow-up and well-coordinated teamwork between the family physician and the institution where the operation was performed.

Arterial thromboembolic complications in patients with Starr-Edwards aortic ball valve prostheses

Aterial thromboembolic complications were studied in 253 patients who had a single aortic Starr-Edwards ball valve implanted. During the first postoperative month, six patients died from myocardial infarction, one was reoperated because of leakage caused by thrombus on the valve, and five others suffered six thromboembolic episodes. Forty-six late thromboembolic complications occurred in 40 of the 216 patients who survived the postoperative period. Seven died, four from cerebral emboli and three from myocardial infarction. The late incidence was 7 episodes per 100 patients per year. Valves of series 1200 carried a significantly higher risk of arterial thromboembolism than did those of series 2300, and most episodes occurred in patients with cell controlled anticoagulant treatment. The incidence was not influenced by time since operation, continuous arrhythmia, concomitant mitral valve disease, heart size, or the degree of intravascular hemolysis. It is concluded that arterial thromboembolic complications represent a major threat to patients with aortic ball valves even several years after operation and in spite of intense anticoagulant therapy.

Experiences with various types of mitral valve prostheses

During the period 1967-1973, four different types of mitral valve prostheses were used by the same surgical group. Altogether 139 patients are included in this study. With the exception of the surgical approach, the operative technique was the same in all groups. The total mortality varied from 17% in the group receiving the Björk-Shiley valve to 40% in the Beall valve group. Thrombo-embolic complications were responsible for three deaths in the Beall and one death in the Lillehei-Nakib group. All patients had been on the adequate anticoagulant therapy. At follow-up, 40 to 77% of the patients had improved functional class, the best results being obtained in the Björk-Shiley group. The diastolic gradients across the prosthetic valves varied from 9 to 4 mmHg at rest. Again, the Björk-Shiley valve gave the most favourable result. The results and significance of the various parameters are briefly discussed.

Current status of the Beall, Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter cardiac valve prostheses

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses--the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves--considered by some to have specific advantages over the Starr-Edwards valves. Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years. Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous. Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.