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Hemolysis Following Cardiac Valve Replacement
Abstract
Destruction of red blood cells is a well-known phenomenon after heart valve replacement. Since the first description, clinically significant hemolysis has continuously decreased as a result of the progress in materials and the improved hemodynamic design of prostheses.
Despite the hemodynamic improvement in cardiac valve prostheses, valve-related deaths and complications have remained a substantial source of morbidity and mortality. This follow-up study was carried out in April, 1986, in a group of 816 patients who received 876 St. Jude Medical prostheses between October, 1977, and October, 1984. One hundred fifty-five patients (37%) of the 422 having aortic valve replacement (AVR) and 88 (29%) of the 300 having mitral valve replacement (MVR) had concomitant coronary artery bypass grafting, and 94 patients (12%) had miscellaneous procedures performed in addition to valve replacement. Sixty-three patients died within the operative period, an operative mortality of 7.7%. Follow-up was complete for 98% of the patients; the mean follow-up was 42 months. At that time, 87 more patients had died, a late mortality of 11.9%. There were 13 valve-related deaths (4 in the AVR group, 7 in the MVR group, and 2 in the miscellaneous group); the causes of death were thromboembolism (7), anticoagulant-related hemorrhage (2), valve thrombosis (2), prosthetic valve endocarditis (1), and perivalvular leak (1). There were 37 thromboembolic episodes (1.78/100 patient-years) and 67 anticoagulant-related hemorrhages (3.22/100 patient-years), 46% of which necessitated transfusion. The incidence of valve thrombosis was 0.6% (4 patients). Perivalvular leak and prosthetic valve endocarditis occurred in 7 patients (1.0%) and 5 patients (0.7%), respectively. Reoperation was carried out in 6 patients (0.8%), but only for perivalvular leak. There were no deaths, no complications, and no clinical evidence of malfunction of the prosthetic valve.(ABSTRACT TRUNCATED AT 250 WORDS)
In der Abteilung für Herzchirurgie des städtischen Krankenhauses München Bogenhausen wurde von Januar 1993 bis Oktober 2000 bei 1092 Patienten entweder die Aorten- und oder die Mitralklappe mit einer Zweiflügelprothese vom Typ Sorin Bicarbon ersetzt. 325 Patienten, die zusätzlich einen aortocoronaren Bypass, bei gleichbestehender KHK, erhielten, wurden von der Auswertung ausgeschlossen. Bei 767 Patienten wurde ein einfacher oder kombinierter prothetischer Klappenersatz durchgeführt. Nach Implantation mechanischer Herzklappenprothesen ist eine dauerhafte Antikoagulation unumgänglich. Ziel der vorliegenden Studie war die Evaluierung der Inzidenz klinischer Komplikationen, insbesondere der Blutungs- und Thromboembolierate nach Implantation, dieser mechanischen Herzklappenprothese im mittelfristigen Verlauf. Bei 553 Patienten wurden Daten hinsichtlich Mortalität, Morbidität und Lebensqualität bzw. NYHA-Klassifikation retrospektiv im Mittel 49 Monate postoperativ erfasst. Zusätzlich wurden die Patienten schriftlich bzw. telephonisch bezüglich ihres postoperativen Verlaufs und jedweder aufgetretener Komplikationen befragt. 131 Patienten mussten von der Auswertung ausgeschlossen werden, da sie weder direkt noch indirekt erreichbar waren. Das untersuchte Patientenkollektiv bestand aus 354 (64%) männlichen und 199 (36%) weiblichen Patienten. Insgesamt wurde in 387 Fällen ein Aortenklappenersatz (AKE) oder bei 118 Patienten ein Mitralklappenersazt (MKE) bzw. in 48 Fällen ein Doppelklappenersatz (DKE=AKE+MKE) durchgeführt. Präoperativ befanden sich 9 Patienten (1,6%) im NYHA- Stadium I, 61 Patienten (11%) im Stadium II, 439 Patienten (79,4%) im Stadium III und 44 Patienten (7,95%) im Stadium IV. Die kumulative follow up Zeit betrug 2250 Patientenjahre (für AKE: 1574 Pj, für MKE: 458 Pj und für DKE: 218 Pj). Hinsichtlich der Ätiologie des Klappenfehlers (AI/AS, MI/MS) zeigten sich folgende Unterschiede in der Langzeitüberlebensraten: In beiden Gruppen wiesen Patienten, die aufgrund einer Insuffizienz operiert wurden eine höhere 8,5- Jahresüberlebensrate (AI: 88,2%, MI: 94%) im Vergleich zu Patienten mit führender Stenosekomponente (AS: 79,5%, MS: 92%). Postoperativ befanden sich über 79% der Patienten im NYHA- Stadium I oder II. Keiner der untersuchten Patienten zeigte eine strukturelle Prothesendysfunktion.
Die Sorin Bicarbon™ Prothese zeigte in der vorliegenden Studie bezüglich Überlebens- und postoperativer Komplikationsrate zufriedenstellende Ergebnisse, die vergleichbar mit anderen auf dem Markt befindlichen Zweiflügelprothesen waren. Weitere follow up’s sind erforderlich für einen Vergleich, der insbesondere die Langzeitergebnisse validieren kann.
Hemolytic and subhemolytic blood damage by mechanical heart valve prostheses have been observed in both clinical and in vitro investigations. A direct comparison between these studies is not possible. Nevertheless the transfer of some in vitro results to the behaviour of the valve in situ may be performed considering the similarity principle. This requires the use of dimensionless similarity numbers such as the plasma's hemoglobin concentration (PHb) or others, instead of dimensioned parameters. To evaluate the in vitro hemolysis of valve prosthesis a test chamber filled with human banked blood was used. An artificial ventricle ensuring an oscillatory flow through the valve was also used. The rise of PHb was evaluated in terms of a similarity number, called the lysis number. This number describes the probability of destroying a single red blood cell participating once in the hemolytic process under consideration. The lysis number, a Björk-Shiley valve (TAD 29), was found to be in the order of 2 x 10(-4). From this, the survival time of erythrocytes in patients with an artificial heart valve was estimated. It was found to be in the order of 20 d of T50 Cr in agreement with clinical results.
Chronic intravascular hemolysis following isolated mitral valve replacement with Bjork-Shiley, Lillehei-Kaster, or Starr-Edwards prostheses was studied in 81 patients. In order to compare the degree of hemolysis to the prosthetic valve function right and left heart hemodynamics were obtained at rest and during exercise. The following laboratory findings were determined: hemoglobin, free hemoglobin into the plasma, reticulocyte count, red cell fragment count, serum bilirubin, serum lactic acid dehydrogenase (LDH), serum haptoglobin, transferrin, hemosiderin in the urine. Haptoglobin was the most sensitive indicator of hemolysis but a good classification of the degree of hemolysis only was possible when combined with LDH. 5% of the Bjork-Shiley, 49% of the Lillehei-Kaster, and 46% of the Starr-Edwards cohort showed chronic intravascular hemolysis which was moderate in 19% of LK, 7% of SE, and 0% of BS patients and mild in the other cases. Severe hemolysis has not been found in patients with regular prosthetic valve function. There was no relationship between hemolysis and single hemodynamic parameters. However, using multiple stepwise regression analysis the variance of LDH could be explained up to 80% by comparing it to the hemodynamics at rest and during exercise.
Hemolysis was found in 67.3 per cent of 208 patients with valve prosthesis. The diagnosis of hemolysis was based on an increased serum lactic dehydrogenase activity (SLDH) with sub-unit liver/heart < 0.8 in 114 patients. In the others, it was determined by increased serum hydroxybutiryl dehydrogenase (HBD), free plasma hemoglobin, and abnormally high reticulocyte count. Excellent correlations existed between SLDH and HBD plasma levels on the one hand, and between SLDH levels and free plasma hemoglobin on the other. Significant hemolytic anemia (hemoglobin < 10.5 Gm. per 100 ml.) was observed in only 5 per cent of these patients, irrespective of iron replacement therapy. The Beall mitral prosthesis was found the most prone to hemolysis, a complication observed in all 12 cases studied. The Starr-Edwards Stellite ball Teflon-covered valve hemolyzes significantly more than the silicone elastomer ball uncovered prosthesis in the aortic and mitral positions. It is felt that the Teflon covering may be an important hemolytic factor in both Starr-Edwards model and Beall prostheses.
In 1091 patients with isolated Björk-Shiley, Lillehei-Kaster, Starr-Edwards, and St. Jude Medical mitral and aortic valve replacement, hemolysis parameters were determined (hemoglobin, LDH, haptoglobin, free plasma hemoglobin, reticulocyte count, serum bilirubin, transferrin, urine hemosiderin, schistocyte count). In 1006 of these patients no valve dysfunction was detected, while in 85 patients either paravalvular leakage or a thrombosis of the prosthetic valve was present. Haptoglobin was the most sensitive parameter for detecting even mild intravascular hemolysis, which was present in two-thirds of patients after alloprosthetic heart valve replacement. For quantifying red cell damage LDH was useful. Hemolysis was somewhat higher after Lillehei-Kaster and Starr-Edwards than after Björk-Shiley or St. Jude Medical implantation. The variance of LDH levels can be explained in a high percentage by correlating them with the hemodynamic findings at rest and exercise, which are indirect parameters of velocity profiles. Hemolysis is higher after aortic than after mitral valve replacement, with the exception of St. Jude valves. In patients with perivalvular leakage or valve thrombosis, red cell damage is more pronounced than in normally functioning prostheses (p less than 0.0005). When the hemolysis characteristics of the individual types of prosthesis are taken into account, the degree of hemolysis is a reliable indicator (p less than 0.05) of the functional integrity of the prosthesis. However, the degree of hemolysis does not correlate with the hemodynamic significance of perivalvular regurgitation.
Das Ausmaß der intravasalen Hämolyse bei künstlichen Herzklappen unter Berücksichtigung unterschiedlicher Prothesentypen und deren Funktion
- L Goppel
- J Küster
- Kl Froer