Long-term results of heart valve replacement with the Edwards Duromedics bileaflet prosthesis: a prospective ten-year clinical follow-up

OBJECTIVE

The Edwards Duromedics valve (Baxter Healthcare Corp., Edwards Division, Santa Ana, Calif.) was designed with a self-irrigating hinge mechanism to reduce thromboembolic complications. After good initial clinical results, distribution was suspended in 1988 after reports of valve fracture after 20,000 valves had been implanted. The manufacturer conducted extensive studies to improve the Edwards Duromedics and reintroduced a modified version, which is available as Edwards Tekna. The purpose of the study was the evaluation of long-term results of the original Edwards Duromedics that might be important for the current version, the Edwards Tekna valve.

METHODS

A prospective clinical 10-year follow-up was performed of 508 patients who underwent valve replacement with the Edwards Duromedics valve in the aortic (n = 268), mitral (n = 183), and aortic and mitral (n = 56) position.

RESULTS

The perioperative mortality rate was 6.9%; follow-up was 98% complete, comprising 3648 patient-years for a mean follow-up of 86 months (range: 33 to 144 months). The actuarial freedom from complications at the 10-year follow-up and the incidence rate (percent per patient-year) were as follows: late mortality rate, 69.2% +/- 2.4% (3.5% per patient-year); thromboembolism, 90.7% +/- 1.6% (0.96% per patient-year); anticoagulation-related hemorrhage, 87.7% +/- 1.7% (1.34% per patient-year); prosthetic valve endocarditis, 96.7% +/- 0.09% (0.38% per patient-year); valve-related mortality rate, 89.3% +/- 1.6% (1.21% per patient-year); valve failure, 86.2% +/- 1.85% (1.54% per patient-year); and valve-related morbidity and mortality rate, 71.1% +/- 2.3% (3.2% per patient-year). Three leaflet escapes were observed (one lethal, two successful reoperations; 99.1% +/- 0.05% freedom, 0.08% per patient-year). All patients functionally improved (86% in New York Heart Association classes I and II), and incidence of anemia was insignificant.

CONCLUSIONS

These results confirm that the Edwards Duromedics valve shows excellent performance concerning thromboembolism, hemolysis, and functional improvement and will serve as a reference for the last version, the Edwards Tekna valve, where comparable long-term data are currently not available.

Hemolysis associated with water administration using a nipple bottle for human infants in juvenile pygmy goats

A 4-month-old, 6.8-kg, castrated male pygmy goat was examined for recurrent episodic fever and red urine of 7 days' duration. A second, 3-month-old, 7-kg, intact female pygmy goat was presented for similar clinical signs. The red discoloration of the urine in each case was determined to be due to hemolysis with subsequent hemoglobinuria. In both cases, hemolysis and hemoglobinuria were closely associated with the goats consuming large volumes of water from a human infant's nipple bottle. A diagnosis of water intoxication-induced hemolysis and hemoglobinuria was made. Episodes of hemoglobinuria in the first case were consistently associated with dilute (specific gravity < 1.010) urine. Water intoxication has been associated with bottle-feeding in human infants and is also widely reported in human psychiatric patients. The small erythrocytes in goats appear to be the most sensitive of the domestic species to hypotonicity-induced hemolysis.

An improved blood substitute. In vivo evaluation of its renal effects

Nephrotoxicity of free hemoglobin (Hb) based blood substitutes still awaits full elucidation. Previous reports attributed Hb passage through the renal glomeruli to a tendency of the Hb tetramer to dissociate into dimers. Now it has become more evident that the Hb tetramer is able to extravasate. It appears that the electrical charge of proteins plays an important role, with electronegativity and a low isoelectric point favoring intravascular persistence. This effect was utilized in the development of an improved blood substitute, comprising Hb reacted with o-ATP and o-adenosine, to form an intra- and intermolecularly cross linked product, which is reduced with glutathione. The modification reagents possess the desired pharmacologic activities and produce an increase in the electronegative charges on the Hb surface. All Hb polymers and chemically modified tetramers present in this solution have a uniform electronegative charge, with a pl of 6.1-6.2. In this present study, unmodified bovine Hb and an improved blood substitute were used for the replacement of 40% of the total blood volume in rats. The nephrotoxic effect was investigated by the determination of urinary output, glomerular filtration rate (GFR), fractional excretion of sodium (FENa), potassium (FEK), and chloride (FECl), urine/plasma osmolality ratio, and urine N-acetyl-beta-D-glucosaminidase (NAG) level. The free Hb and non heme protein contents in the urine were analyzed by using isoelectric focusing and size exclusion liquid chromatography methods. The results indicate that unmodified Hb is nephrotoxic. An initially elevated urinary output was followed by a significant oliguria associated with decreased GFR, FEK, and FECl and elevated FENa and NAG. Severe hemoglobinuria was associated with proteinuria. Analysis of urine from unmodified Hb treated rats revealed the presence of Hb tetramers. Histopathological examination of the kidneys showed cytoplasmic vacuolization of proximal tubular epithelium. On the contrary, an improved blood substitute did not produce any nephrotoxic reactions. It was found that this Hb solution did not pass through the renal glomerular barrier and was not present in urine samples. In conclusion, such a chemical and pharmacological alteration of Hb molecules reduced their interaction with renal glomeruli and suspended nephrotoxicity.

The impact of polyethylene glycol conjugation on bovine hemoglobin's circulatory half-life and renal effects in a rabbit top-loaded transfusion model

This study compares the effects of polyethylene glycol (PEG) modified bovine hemoglobin on vascular half-life and renal function in rabbits to those of unmodified bovine hemoglobin. Renal function was assessed by the measurement of the glomerular filtration rate, urinalysis, blood chemistries, hemoglobin (Hb) excretion rates, and tissue histology. The influence of infusion rates on hemoglobin excretion rates and organ morphology was also examined. The mean half-life of unmodified bovine hemoglobin was 3.0 +/- 0.1 (mean +/- SEM) h, which was extended 14-fold to 43.2 +/- 1.7 h following PEG conjugation. The glomerular filtration rate, urinalysis, and blood chemistries were not greatly affected by either the unmodified bovine hemoglobin or the PEG modified bovine hemoglobin. However, unmodified bovine hemoglobin did demonstrate significant hemoglobinuria (Hb excretion levels in excess of 1.0% of the infused dose [p < 0.05]) at all infusion rates given while PEG modified bovine hemoglobin did not. In addition, histological examination by light microscopy indicated that the most severe morphological changes occurred in animals that received unmodified bovine hemoglobin. This data suggests that PEG modification of bovine hemoglobin significantly reduced some of the adverse effects of bovine hemoglobin on renal physiology and morphology.

Therapeutic efficacy of atovaquone against the bovine intraerythrocytic parasite, Babesia divergens

This study demonstrates the activity of the hydroxynaphthoquinone (HNQ), atovaquone, against Babesia divergens, the cause of a rare but lethal form of human babesiosis. In vitro studies showed that unlike other anti-malarial drugs, the HNQs studied have a high level of anti-babesial activity and atovaquone was more active than imidocarb, the most effective compound used so far for human B. divergens babesiosis and also used routinely for the treatment of bovine babesiosis. Atovaquone also proved to be extremely active against B. divergens in gerbils (Meriones unguiculatus). Acute fulminating infections were effectively treated with as little as 1.0 mg/kg with increasing effectiveness up to 10 mg/kg, which compares well with the activity of imidocarb. Although immunosuppression with dexamethasone slowed the decline of parasitemias after treatment with atovaquone, gerbil survival was unaffected. Pretreatment of gerbils with 4 daily low doses of atovaquone did not have any effect on the development of subsequent infections. However, if treatment was continued after infection, daily doses as low as 0.5 mg/kg effectively suppressed the parasites.

Balloon-occluded retrograde transvenous obliteration for gastric varices with gastrorenal or gastrocaval collaterals

OBJECTIVE

The purpose of this study was to evaluate the efficacy of balloon-occluded retrograde transvenous obliteration for gastric varices with gastrorenal or gastrocaval collaterals.

SUBJECTS AND METHODS

Thirty patients who had gastric varices with gastrorenal or gastrocaval collaterals underwent balloon-occluded retrograde transvenous obliteration. A 5-French balloon catheter was inserted in the gastrorenal collateral, gastrocaval collateral, or both, and a 5% solution of ethanolamine oleate iopamidole that contained equal amounts of ethanolamine oleate and iopamidole 300 was injected into the gastric varices. One day, 1 week, and 1 month after balloon-occluded retrograde transvenous obliteration, hepatic and renal function tests (total bilirubin, transaminase, blood ammonia, serum creatinine, and blood urea nitrogen) were done. To evaluate therapeutic efficacy, we observed the site with endoscopy every 2 weeks and obtained enhanced CT scans every month. The observation time ranged from 10 to 30 months.

RESULTS

After balloon-occluded retrograde transvenous obliteration, gastric varices disappeared completely in all 30 cases in 4-16 weeks (mean, 10 weeks). Recurrence of gastric varices was observed in three cases (10%), which were treated with repeated balloon-occluded retrograde transvenous obliteration. Esophageal varices were aggravated in three patients (10%), who underwent successful endoscopic injection sclerotherapy. Complications of balloon-occluded retrograde transvenous obliteration were fever and hemoglobinuria, which disappeared in about 5 days. We observed no significant hepatic and renal functional damage.

CONCLUSION

Balloon-occluded retrograde transvenous obliteration offers good control of gastric varices with gastrorenal or gastrocaval collaterals, even if hepatic function is poor.

Severe hemoglobinuria masquerading as gross hematuria following mitral valve replacement

Gross hemoglobinuria following mitral valve replacement can represent a rare form of hemolytic anemia. This condition can masquerade as gross hematuria in the post-valve replacement patient. It is commonly associated with valvular dysfunction, specifically, perivalvular leakage. The leakage may not be apparent on routine echocardiography but it may be documented with trans-esophageal echocardiography.

Erythrocyte fragility and chronic intermittent pigmenturia in a dog

A 2-year-old spayed female Shetland Sheepdog had recurrent episodes of discolored urine. Treatments administered for presumed urinary tract infection did not prevent recurrence. Episodes of pigmenturia appeared to correlate with stressful situations or excessive activity. Examination of urine sediment consistently revealed that RBC were not evident, despite a positive result for blood on urinalysis. This was suggestive of hemoglobinuria, and diagnostic testing was instituted to determine the underlying cause. Results of alkaline and osmotic fragility tests were useful in determining that an increase in erythrocyte fragility was the underlying cause of the recurrent pigmenturia. Erythrocyte fragility testing should be considered in animals that do not respond to appropriate treatments for pigmenturia.

An etiologic study of hemoglobinuria and blackwater fever in the Kivu Mountains, Zaire

Between January 1985 and March 1986, in the high altitude area of Kivu, Eastern Zaïre, 38 patients presenting with hemoglobinuria as main manifestation were investigated. Profound glucose-6-phosphate dehydrogenase deficiency was detected in 4 patients, leptospirosis in 2 and Hantaan virus infection in 2. Hemolysis was doubtful (haptoglobin > 40 mg/dl, Hemoglobin > 12 g/dl) in 2 patients. Other potential causes of hemoglobinuria such as hemoglobinopathy, toxic agents, infectious diseases or blood transfusion incompatibility were carefully screened and excluded. The syndrome observed in the remaining 28 cases was strongly suggestive of blackwater fever (BWF) as described in malaria patients by several authors under the french name "fièvre bilieuse hémoglobinurique". Quinine was used as curative treatment of malaria before admission in a significant greater proportion (p < 0.01) of patients with BWF compared to patients with uncomplicated malaria, suggesting that this drug might have played a triggering role in the genesis of BWF. However, quinine was usually administered at inadequate doses to malaria patients non responding to chloroquine and belonging to a population of whom 50% are non immune. It may thus also be hypothesized that BWF in our patients could result from a hyperparasitemic state that remained undetected because of an unusual synchronous lysis of infected erythrocytes. In the latter case BWF would correspond to a major complication of falciparum malaria only coincidentally related to the use of quinine.

A case of mumps associated with acute hemolytic crisis resulting in hemoglobinuria and acute renal failure

A 13-year-old boy presented with acute hemolytic anemia a few days after mumps infection. The ensuing hemoglobinuria resulted in acute renal failure in this child, which was corrected with fluid and alkali therapy. We draw attention to this uncommon complication of mumps and the need for careful evaluation.

Hemoglobinuria in rats: a sensitive test of renal filtering and absorption of PEG-hemoglobin, a red blood cell substitute

Hemoglobinuria, defined as hemoglobin or hemoglobin subunits in the urine, is an easily monitored, sensitive indicator of renal handling of hemoglobin-based blood substitutes. Hemoglobin tetramer dissociation increases filtration by the kidneys. When the rate of filtration exceeds reabsorption, hemoglobinuria occurs. This study investigates the renal filtration and absorption of polyethylene glycol-modified bovine hemoglobin by monitoring for hemoglobinuria in several model systems.

Production of PEG-modified bovine hemoglobin: economics and feasibility

Bovine hemoglobin has many advantages as a blood substitute: a) it's ready availability; b) it's low cost; c) it's oxygen carrying capacity; and d) the ease with which it can be modified with polyethylene glycol (PEG) to improve its pharmacokinetic profile. This study investigates the potential of PEG-modified bovine hemoglobin as a cost-effective blood substitute.

Hemolytic effect of the Amplatz thrombectomy device

PURPOSE

The hemolytic effect of the Amplatz thrombectomy device (ATD) was evaluated in nine dogs and in nine patients.

MATERIALS AND METHODS

The device was activated for 1-2 minutes in the abdominal aorta, inferior vena cava, or femoral artery of nine dogs. The device was activated for 1-4 minutes in the nine patients in occluded lower extremity bypass grafts (n = 5), native superficial femoral artery (n = 1), a pulmonary artery embolus (n = 1), a portocaval shunt (n = 1), and an iliac vein stent (n = 1). Patients were examined for laboratory evidence of hemolysis following mechanical thrombectomy.

RESULTS

In all dogs haptoglobin level decreased, free hemoglobin level in the plasma increased, and hemoglobinuria was present. There was no change in renal function. The level of haptoglobin decreased and the level of plasma free hemoglobin increased in eight patients, with hemoglobinuria detected in one. More hemolysis was observed in the animals than in the patients.

CONCLUSION

The ATD has a definite transient hemolytic effect. Until further studied, it should not be used in children and should be used with caution in patients who are anemic, hypoxemic, or have potentially reversible renal insufficiency. Activation time should be monitored closely because hemolysis probably increases with increasing activation time.

Human hemoglobin conjugated to carboxylate dextran as a potential red blood cell substitute. II--Pharmacotoxicological evaluation

A solution of human hemoglobin bound to benzene tetracarboxylate substituted dextran, whose physicochemical characteristics are defined in part I, was evaluated in vivo as a potential red blood cell substitute. Further experiments show: - the confirmation of a lack of acute toxicity in mice and guinea pigs after injection of 12.5%, 25% and 50% of the blood mass and the absence of death in rabbits having undergone three successive 25% hemorrhagic shocks in three week intervals. A plasma half-life of 9.5 +/- 0.5 hours in 70-75% hemorrhagic shocks on guinea pigs and the absence of dex-BTC-Hb in thoracic and abdominal cavities. No tissue oedema was noticed. Total hemoglobinuria did not exceed 10% of the injected hemoglobin quantity and only involved free hemoglobin. A lack of death in 70-75% hemorrhagic shocks and survival times ranging from 10 hours to 3 days in total exchange transfusions in guinea pig experiments.

Acute hemolysis in glutathione peroxidase deficiency

Severe acute hemoglobinemia and hemoglobinuria developed in a 17-year-old Japanese male with no history of exposure to any oxidizing agents. Examination of erythrocyte enzyme activity revealed that the patient's erythrocyte glutathione peroxidase (GSH-Px) activity was decreased to about a half that in control cells. Serum selenium (Se) concentration was within normal limits. Family studies showed that GSH-Px activity in the erythrocytes of two siblings was similarly decreased. It was suggested that the proband was suffering from a hereditary heterozygous GSH-Px deficiency, which appeared to be associated with acute hemolysis.

Intraoperative peripheral rotary atherectomy: early and late clinical results

Early and late clinical results of intraoperative peripheral atherectomy using the Auth Rotablator are analyzed. Twenty patients (15 males and 5 females age 39-89 years, mean 70 years) underwent 25 atherectomy procedures for peripheral arterial occlusive disease from August 1987 to October 1989. All patients underwent serial history, physical exam, and Doppler pressure measurements preoperatively and then postoperatively at 24 hours, one week, one month, and six months during a follow-up period of 15 to 41 months, mean 27 months. Preoperative and intraoperative completion follow-up arteriography was done in all cases and follow-up arteriography in 19 of 25 cases. Initial arteriographic success was achieved in 23/25 (92%) cases and in 39/41 (93%) arterial segments (superficial femoral artery 12/13, popliteal 14/15, tibial 12/13, profunda-femoral 1/1). Complications included intimal dissection (1), equipment breakage (2), minor emboli (3), major emboli with thigh skin loss (1), transient hemoglobinuria (4), wound hematoma (1), wound infection (1), and limb loss (1). Early thrombosis occurred in five cases to give an in-hospital success rate of 18/25 (72%). Primary patency was 66% at six months but only 12% at two years. Rotary atherectomy effectively recanalizes femoral, popliteal and tibial arteries. However, early thromboembolic complications occurred frequently, and the two year patency was dismal. Rotary atherectomy is not recommended for general use until problems of thromboemboli and intimal hyperplasia are solved.

Common reactions to transfusions

A blood transfusion is a special kind of transplantation, with the transfer of living tissue from one person to another. Reactions can occur with as little as 10 to 15 ml of incompatible blood. The onset of a reaction may be misleading or delayed, and its detection requires astute assessment. Responsibility for recognition of a transfusion reaction lies with the transfusionist, who is often a nurse. The following types of response can occur: hemolytic reactions, transfusion-induced graft-versus-host disease, hemoglobinuria, purpura, fever, circulatory overload, thrombophlebitis, urticaria, hyperkalemia, asymptomatic hemoglobinuria, pulmonary edema, and allergic and anaphylactic reactions. Critical care nurses need to be aware of the dangers of blood and blood product transfusions and to be prepared to react quickly.

Exertional (march) haemoglobinuria

The case history is presented of two patients with attacks of cherry-red urine after strenuous exercise. Both had varicosity of the long saphenous veins. Haemoglobinuria disappeared after crossectomy of the long saphenous vein and resection of the convolutes. After one and two years, they have no recurrence.

Pigment-induced nephropathy after sjambok injuries

During a 12-month period, 42 patients required admission to hospital after sjambok beatings. Eighteen showed no abnormality of serum electrolyte values or renal function but urinary pigment precipitation was present in 9 patients. A further 16 patients demonstrated abnormalities of serum urea and electrolyte values, the commonest of which was a subnormal venous carbon dioxide content, in conjunction with urinary pigment precipitation in 14 cases. The remaining 8 patients presented with, or developed, varying degrees of renal failure. In 4 of these patients, the sole initial biochemical abnormality was a subnormal venous carbon dioxide level. Based on the initial laboratory findings, four groups of patients may be identified with gradations of soft-tissue injury. Recognition of those patients at risk of developing crush syndrome is facilitated and appropriate treatment may be instituted at an early stage thereby reducing morbidity and mortality.

Regulation of renal function in thermal injury

Hypovolemia, low cardiac output, and systemic vasoconstriction are major etiologic factors in acute renal failure occurring in the early postburn period, and elevated levels of stress-related hormones (catecholamines, angiotensin, aldosterone, and vasopressin) are implicated in the mechanism. By counteracting the effects of the hormones, atrial natriuretic polypeptide (ANP) regulates the renal response to burns. ANP was elevated after burns, protecting the kidneys by increasing renal blood flow and urine output. In pulmonary acid injury, increased ANP levels were associated with natriuresis which was reduced by administration of anti-ANP serum. Exogenous ANP given to dogs under constant norepinephrine infusion resulted in improvement of hemodynamic and renal parameters. To prevent tubular damage due to hemoglobinuria, a haptoglobin preparation is administered to patients with extensive third-degree burns. With sufficient fluid replacement, these new treatments will reduce the incidence of acute renal failure in the early postburn period.

Haemoglobinuria due to Clostridium perfringens type A mastitis in a ewe

A 2-year-old Suffolk gimmer presented with clinical signs of haemoglobinuria, jaundice, anaemia and acute mastitis. Clinical investigation and bacteriological examination of milk samples revealed Clostridium perfringens type A to be the causal agent.