Erythrocyte destruction in different types of Starr-Edwards aortic ball valves

A randomized comparison of the MCRI On-X and CarboMedics Top Hat bileaflet mechanical replacement aortic valves: Early postoperative hemodynamic function and clinical events

OBJECTIVE

This study compared hemodynamic function and clinical events in consecutive patients randomly assigned to receive a wholly supra-annular replacement valve or a valve with an intra-annular component.

METHODS

Fifty-two patients with an average age of 62 years (range 40-74 years) were sized for both a CarboMedics Top Hat valve (CarboMedics Inc, Austin, Tex) and an MCRI On-X valve (Medical Carbon Research Institute, LLC, Austin, Tex) before random assignment to receive either valve type. Echocardiographic and clinical assessments were performed in the immediate postoperative period and at 1 year.

RESULTS

The mean effective orifice areas were 1.41 +/- 0.42 cm2 for the Top Hat and 2.17 +/- 0.78 cm2 for the On-X (P < .0001). The mean pressure differences were 12.2 +/- 4.4 mm Hg and 6.9 +/- 3.6 mm Hg, respectively (P < .0001). New York Heart Association functional class was better with the On-X than the Top Hat valves, but there were no differences in clinical events, regression of left ventricular mass, or measures of hemolysis.

CONCLUSION

The partially intra-annular MCRI On-X valve was hemodynamically superior to the wholly supra-annular CarboMedics Top Hat valve. However, there were no differences in early clinical outcomes between the two valve types.

In-vitro wall shear measurements at aortic valve prostheses

Wall shear distributions during the cardiac cycle at the valve rings of Starr-Edwards, Björk-Shiley and Lillehei-Kaster aortic valves are measured and compared with thresholds reported for shear-induced trauma of blood components. Further, for the disk valves, the influence of pulse rate on wall shear stresses is evaluated. Hot film anemometry with flush-mounted wall shear probes is used as measurement technique in a pulsatile flow mock circuit. The experimental systolic data support the better hemodynamic characteristics of the disk valves over the ball valve also with respect to the threshold shear stresses of flow induced blood trauma. These results are confirmed by postoperative clinical studies, where lower LDH-values are found with the disk than with the ball valves. During diastole, however, high shear stresses are measured and calculated at the valve ring of the Björk-Shiley prosthesis, which can be referred to the non-overlapping closing mechanism. This result is discussed with respect to the often observed thrombus formation at the disk downstream of the smaller orifice of the Björk-Shiley valve.

Chronic intravascular hemolysis after aortic valve replacement with Ionescu-Shiley xenograft: comparative study with Bjork-Shiley prosthesis

Twenty patients with a prosthetic valve (Ionescu-Shiley or Bjork-Shiley) in the aortic position were studied for evidence of intravascular hemolysis. Serum lactic dehydrogenase and serum haptoglobin levels were used as the most sensitive indicators of hemolysis. Elevated concentrations of lactic dehydrogenase were found in all 10 patients with an Ionescu-Shiley prosthesis (mean 402 IU/liter) and in 7 of 10 patients with a Bjork-Shiley prosthesis (mean 234 IU/liter). The mean serum haptoglobin was 15 mg/dl (range 10 to 28) in patients with the Ionescu-Shiley valve and 96 mg/dl (15 to 284) for those with the Bjork-Shiley valve. This study indicates the presence of chronic intravascular hemolysis in patients with the Ionescu-Shiley aortic valve. The increase in lactic dehydrogenase was significantly greater in patients with the Ionescu-Shiley prosthesis than in those with the Bjork-Shiley prosthesis, indicating a slightly shorter red cell life span in the former group.

Aortic valve replacement. A randomized study comparing Björk-Shiley and Lillehei-Kaster disc valves. Haematological evaluation

In this study, 79 randomized patients with either Björk-Shiley (B-S) or Lillehei-Kaster (L-K) aortic disc valves were re-admitted two years after operation for clinical, haemodynamic and haematological evaluation. This paper deals in particular with the haematological results. Cine-aortography was carried out in 76 patients and left ventricular catheterization via the transseptal approach was performed in 43 patients. Haemoglobin concentration, erythrocyte count, platlet count, reticulocyte count, plasma haemoglobin concentration, serum bilirubin, serum iron, serum haptoglobin and serum lactate dehydrogenase were studied in the patients. Postoperatively all patients had normal haemoglobin and erythrocyte count. Haptoglobin was absent or reduced in 43% of patients with B-S valves and in 65% of those with L-K valves. Serum lactate dehydrogenase activity (LDH) was abnormally elevated in 26% of patients in the B-S group and in 65% of those in the L-K group. Mean LDH was significantly higher in the L-K group compared with the B-S group (p less than 0.01). A highly significant linear correlation could be demonstrated between mean systolic pressure difference across the valve (delta pm) and LDH (p less than 0.001). This finding helps to explain why the L-K valves provoke more erythrocyte destruction than the B-S valves, since delta pm proved to be significantly higher in the L-K group. LDH was not significantly increased in 6 patients in whom a paravalvular leakage was demonstrated.

Leukocyte function after aortic valve replacement

Leukocyte function was studied in patients with prosthetic heart valves by oxygen consumption measurements during phagocytosis of polystyrene latex particles. The consumption reflects the phagocytotic capacity of the cells. In 38 patients with Starr-Edwards aortic ball valves the mean oxygen consumption was 3.95 nanoatoms per minute per 10(6) leukocytes, as compared to 4.15 in 50 healthy subjects, the difference not being statistically significant. The number of leukocytes per ml. of blood and the distribution of cell types was quite similar in the two groups, although slightly more younger cells were found in the patients. It is concluded that the capacity for phagocytosis is not significantly reduced after aortic ball valve implantation.

Intravascular hemolysis in the late course of aortic valve

The degree of intravascular hemolysis was evaluated in 315 patients in the late course of aortic valve replacement. Starr-Edwards aortic ball valves of series 2300 caused significantly more hemolysis than did those of series 1200, as estimated from the serum lactate dehydrogenase levels. Smaller valves of series 2300 caused a higher degree of hemolysis than did the larger ones. Aortic disc valves induced a more moderate red cell destruction than did the ball valves, the Lillehei-Kaster significantly more than the Bjørk-Shiley prostheses. Crushing of red cells is thought to be a more important cause of hemolysis than shearing forces in turbulent blood. Hemolytic anemia represented a problem only in some patients with Starr-Edwards valve type 2300, although iron substitution was necessary also in some with other prostheses, since the hemoglobin-binding capacity of haptoglobin was exceeded in several patients. Valvular or paravalvular leakage was associated with stronger hemolysis in some patients, and should be suspected whenever the rate of red cell destruction increases. Longstanding intravascular hemolysis did not seriously affect renal function.

Platelet functions in patients with aortic ball valves

Platelet functions were studied in normal subjects and patients with single Staff-Edwards aortic ball valves of series 1200 and 2300. The most pronounced changes were found in platelet adhesiveness, measured with Hellem's modified method. The mean percentage of adhesive platelets was reduced from 71.8 in normal subjects to 50.9 in patients with valve type 1200 and to 27.2 in those with type 2300. An inverse correlation was found between platelet adhesiveness and the degree of intravascular hemolysis, as reflected by serum LDH levels. The mean bleeding time was significantly prolonged in patients with valve 2300, and the individual values correlated inversely to the adhesiveness. The mean values of platelet counts, or irreversible aggregation induced by collagen or epinephrine, and of platelet survival were all moderately-but significantly-reduced as compared to normal. The most important mechanism behind the disturbed platelet reactivity is probably mechanical damage of the platelets by the valve, whereas refractoriness of platelets toward ADP liberated from red cells as well as consumption of adhesive platelets by thrombus formation is thought to have limited influence on platelet behavior. Platelet function was altered to the same extent in patients with a history of arterial thromboembolic complications as in those without. The disturbed platelet reactivity may predispose to bleeding, but may also offer some protection against arterial thromboembolism.

Arterial thromboembolic complications in patients with Björk-Shiley and Lillehei-Kaster aortic disc valve prostheses

Arterial thromboembolic complications were studied in 196 patients who had either a single Björk-Shiley or Lillehei-Kaster aortic disc valve implanted. Eight patients suffered from such complications in the course of the first postoperative month and three of them died, two from myocardial infarction and one from cerebral embolism. Nineteen late thromboembolic complications developed in 18 of the 164 patients who survived the postoperative period, the incidence bein 5.9 episodes per 100 patients per year. The two valve types wer found to be equallly thrombogenic, and the rate was not lower than that in patients with Starr-Edwards aortic ball valves of series 2,300 previously studied. Particularly serious was valve malfunction caused by thrombi that limited the movement of the discs. Early recognition of this condition is essential, because the only effective therapy is removal of the thrombus. Three patients with a Björk-Shiley and one with a Lillehei-Kaster valve suffered this complecation and two died, while cerebral embolism caused a third late death. Two of the three patients who had not received anticoagulants developed thromboembolic complications, while most episodes occurred in spite of well-maintained anti-coagulant treatment. It is concluded that arterial thromboembolic complications remain a considerable problem also after aortic disc valve implantation, and that thrombotic valve malfunction is particularly serious and requires special attention.

The effect of propranolol on hemolysis in patients with an aortic prosthetic valve

Propranolol was given to five patients with severe hemolytic anemia from arotic prostheses. Red cell survival, lactic dehydrogenase, serum hemoglobin, and 24 hour urine iron values were used to evaluate the severity of hemolysis with and without propranolol treatment. Three patients had a clear decrease in the level of hemolysis with propranolol therapy. One patient developed congestive failure after 6 months on propranolol. The decrease in hemolysis is most likely related to a slower heart rate.

Surface ultrastructure of silicone rubber aortic valve poppetts after long-term implantation. A scanning electron microscope study of four poppets

The surface ultrastructure, demonstrated by scanning electron microscopy, is described in four implanted Silastic aortic valve poppets. Ball variance was discovered at necropsy in two patients and clinically in one in whom the poppet was replaced. The fourth patient underwent reoperation, but ball variance was neither suspected nor found. All four poppets were densely coated with biological debris and microthrombi. The 'coat' was soluble in a weak solution of sodium hydroxide. The true Silastic surface beneath the coat was little altered compared with unimplanted poppets, even after 10 years' implantation.

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.

Experimental evaluation of mechanical haemolysis with Starr-Edwards, Kay-Shiley and Björk-Shiley valves

Mechanical cell damage was studied in vitro with three types of prostheses: Starr-Edwards, Kay-Shiley and Björk-Shiley valves. Mechanical cell damage was found to be closely related to the flow characteristics in the prosthesis. Considering valves of similar orifice diameter, Björk-Shiley valves produced the lowest rate of haemolysis. This is due to the improved haemodynamic characteristics of the valve which resulted from the laminar type of flow. With Starr-Edwards valves, smaller sizes produced unacceptably high rates of haemolysis. Increasing the mean forward flow across the valve resulted in a disproportionate rise in the energy loss and the rate of haemolysis when compared with Björk-Shiley valves of similar annulus diameters.

Hemolysis in the aortic prosthetic valve

A review of the incidence and severity of hemolysis in the aortic prosthesis is presented. The noncloth-covered Starr-Edwards prosthetic series 1000, 1200, and 1260 had a 2 percent (1/54) incidence of anemia. The cloth-covered Starr-Edwards aortic prosthetic series 2300 was associated with anemia in 61 percent (28/46) of patients. The modified aortic prosthetic series 2310 and 2320 had a 34 percent (19/56) incidence. Mean lactic dehydrogenase levels for the series 1000, 1200 and 1260 were 184 units; 2300 series, 574 units; 2310 and 2320 series, 334 units; and the Bjork-Shiley aortic prosthesis, 166 units. Nine patients underwent repeat surgery because of refractory anemia in the 2300 series, and one did so in the 2310 series. Four of the patients with repeat surgery had significant cloth wearing of the valve. A transvalvular gradient in excess of 30 mm Hg was present in seven of ten anemic patients studied who had the series-2300 valve. The cloth-covered Starr-Edwards aortic prosthesis carries a significant risk of anemia. At the present time the 2310 and 2320 series cause less hemolysis and a lower incidence of anemia than the original 2300 series but in excess of the noncloth-covered Starr-Edwards prosthesis.

Diagnosis and management of complications of prosthetic heart valves

Complications after heart valve replacement remain a substantial source of morbidity and mortality despite continuing advances in surgical care and prosthetic design. Infectious endocarditis occurs in about 4 percent of patients and may appear early (within 60 days) or late after operation. Endocarditis of early onset is commonly due to staphylococcal, fungal or gram-negative organisms and is fatal in 70 percent or more of cases. Infection of late onset is more often of streptococcal origin and the mortality rate is lower, about 35 percent. With either type, prompt recognition, vigorous and appropriate antimicrobial therapy and early consideration of surgical intervention are crucial. The postperfusion and postpericardiotomy syndromes are relatively common and relatively benign syndromes associated with postoperative fever. Their recognition is important to prevent confusion with endocarditis or sepsis and thus to reassure the patient and physician. Treatment is primarily symptomatic. Intravascular hemolysis occurs with most prosthetic heart valves but is more common with certain prostheses and with paraprosthetic valve regurgitation, with significant hemolytic anemia in 5 to 15 percent. Oral iron replacement therapy is effective in the majority of patients, but occasionally blood transfusion or reoperation for leak around the prosthesis is necessary. Prosthesis dysfunction due to thrombus may be recognized clinically by recurrence of heart failure, syncope, cardiomegaly and altered prosthetic valve sounds or new murmurs. Hemodynamic studies verify the diagnosis, and prompt reoperation is indicated for this potentially lethal problem. Systemic embolization has decreased markedly with the introduction of cloth-covered prostheses and is frequently related to erratic or ineffective anticoagulant therapy. We continue to recommend anticoagulant therapy for all patients with prosthetic heart valves unless there is a major contraindication.

Effects of dipyridamole and acetylsalicylic acid on platelet functions in patients with aortic ball-valve prostheses

The effects of dipyridamole and ASA on platelet functions were studied in patients with aortic ball-valve prostheses. Before ingestion, platelet adhesiveness was markedly reduced and platelet survival time slightly, but insignificantly shortened. ASA prolonged the bleeding time, reduced collagen-induced platelet aggregation, and inhibited secondary aggregation initiated by adrenalin. Similar effects were obtained with 2 Gm. of ASA alone as with 1 Gm. daily in combination with 225 mg. of dipyridamole. Platelet adhesiveness remained low. Depyridamole alone, 375 mg. daily, did not influence any of these parameters. The mean platelet half-life was prolonged from 3.52 to 3.72 days by each drug and to 4 days by the combined treatment. None of the differences was, however, statistically significant. A clinical study with ASA has been started in a larger series of patients to evaluate the effect on arterial thromboembolism.

Haemolysis with Björk-Shiley and Starr-Edwards prosthetic heart valves: a comparative study

Slater, S. D., Sallam, I. A., Bain, W. H., Turner, M. A., and Lawrie, T. D. V. (1974).Thorax, 29, 624-632. Haemolysis with Björk-Shiley and Starr-Edwards prosthetic heart valves: a comparative study. A comparison was made of the haemolytic complications in 85 patients with two different types of Starr-Edwards cloth-covered ball and cage prosthesis with those in 44 patients with the Björk-Shiley tilting disc valve. Intravascular haemolysis, as detected by the presence of haemosiderinuria, occurred significantly less often with the Björk-Shiley than with the Starr-Edwards valve, the overall incidence with aortic, mitral or multiple replacements being 31%, 15%, and 20% for Björk-Shiley and 94%, 92%, and 88% for Starr-Edwards valves respectively. There was no significant difference in the frequency of haemolysis between each of the two types of Starr-Edwards prosthesis studied at either the aortic (2300 versus 2310 model) or mitral (6300 versus 6310) site.

Haemolytic anaemia developed in only one patient with a Björk-Shiley valve but was common though usually mild with Starr-Edwards prostheses, particularly aortic valve replacements with the 2300 model and in aortic plus mitral (± tricuspid) replacements. The greater severity of haemolysis produced by Starr-Edwards valves, again especially of the latter types, was further demonstrated by higher serum lactate dehydrogenase and 24-hour urinary iron levels.

It is concluded that the Björk-Shiley tilting disc valve represents a significant advance in the amelioration of the haemolytic complications of prosthetic valves.