Acute Kidney Injury Resulting From Hemoglobinuria After Pulsed-Field Ablation in Atrial Fibrillation: Is it Preventable?

BACKGROUND: High-voltage pulses can cause hemolysis. OBJECTIVES: The authors evaluated the occurrence of hemoglobinuria after pulsed-field ablation (PFA) and its impact on renal function in patients with atrial fibrillation (AF). METHODS: A consecutive series of patients with AF undergoing PFA were included in this analysis. The initial patients who did not receive postablation hydration immediately after the procedure were classified as group 1 (n = 28), and the rest of the study patients who received planned fluid infusion (0.9% sodium chloride ≥2 L) after the procedure were categorized as group 2 (n = 75). RESULTS: Of the 28 patients in group 1, 21 (75%) experienced hemoglobinuria during the 24 hours after catheter ablation. The mean postablation serum creatinine (S-Cr) was significantly higher than the baseline value in those 21 patients (1.46 ± 0.28 mg/dL vs 0.86 ± 0.24 mg/dL, P < 0.001). Of those 21 patients, 4 (19%) had S-Cr. >2.5 mg/dL (mean: 2.95 ± 0.21 mg/dL). The mean number of PF applications was significantly higher in those 4 patients than in the other 17 patients experiencing hemoglobinuria (94.63 ± 3.20 vs 46.75 ± 9.10, P < 0.001). In group 2 patients, no significant changes in S-Cr were noted. The group 2 patients received significantly higher amounts of fluid infusion after catheter ablation than did those in group 1 (2,082.50 ± 258.08 mL vs 494.01 ± 71.65 mL, P < 0.001). In multivariable analysis, both hydration (R2 = 0.63, P < 0.01) and number of PFA applications (R2 = 0.33, P < 0.01) were independent predictors of postprocedure acute kidney injury. CONCLUSIONS: On the basis of our findings, both the number of PFA applications and postablation hydration were independent predictors of renal insult that could be prevented using planned fluid infusion immediately after the procedure.

Congenital CD59 Deficiency.

The severe clinical symptoms of inherited CD59 deficiency confirm the importance of CD59 as essential complement regulatory protein for protection of cells against complement attack, in particular protection of hematopoietic cells and human neuronal tissue. Targeted complement inhibition might become a treatment option as suggested by a case report. The easy diagnostic approach by flow cytometry and the advent of a new treatment option should increase the awareness of this rare differential diagnosis and lead to further studies on their pathophysiology.

Cardiopulmonary bypass-associated acute kidney injury: a pigment nephropathy?

Acute kidney injury (AKI) is a common and serious postoperative complication following exposure to cardiopulmonary bypass (CPB). Several mechanisms have been proposed by which the kidney can be damaged and interventional studies addressing known targets of renal injury have been undertaken in an attempt to prevent or attenuate CPB-associated AKI. However, no definitive strategy appears to protect a broad heterogeneous population of cardiac surgery patients from CPB-associated AKI. Although the association between hemoglobinuria and the development of AKI was recognized many years ago, this idea has not been sufficiently acknowledged in past and current clinical research in the context of cardiac surgery-related AKI. Hemoglobin-induced renal injury may be a major contributor to CPB-associated AKI. Accordingly, we now describe in detail the mechanisms by which hemoglobinuria may induce renal injury and raise the question as to whether CPB-associated AKI may actually be, in a significant part, a form of pigment nephropathy where hemoglobin is the pigment responsible for renal injury. If CPB-associated AKI is a pigment nephropathy, alkalinization of urine with sodium bicarbonate might protect from: (1) tubular cast formation from met-hemoglobin; (2) proximal tubular cell necrosis by reduced endocytotic hemoglobin uptake, and (3) free iron-mediated radical oxygen species production and related injury. Sodium bicarbonate is safe, simple to administer and inexpensive. If part of AKI after CPB is truly secondary to hemoglobin-induced pigment nephropathy, prophylactic sodium bicarbonate infusion might help attenuate it. A trial of such treatment might be a reasonable future investigation in higher risk patients receiving CPB.

The design and application of a pediatric centrifugal pump.

This centrifugal pump (CP) includes two parts: the blood pump and the driving apparatus. They are connected by six twin magnetic disc plates and driven by a magnetic DC motor (120W). The blood pump had six leaves deadlocked between two plastic discs. Six leaves were set at 30 degrees angles, separately. In the lower chamber of the CP, there was an inlay magnetic disc, which is connected with the disc leaves by an axis. This axis was sealed by silicon rubber and a ceramic ring. The priming volume of the blood chamber was 34 ml. In vitro testing showed that the free hemoglobin caused by the CP was much less than that caused by a roller pump after 180 min. The effect of this CP on blood cell damage was also studied in an animal model. Six goats were placed on cardiopulmonary bypass for 180 min. Perfusion flow rates were maintained between 1.5 and 2.5 L/min. The plasma free hemoglobin was lower in the CP group (6.04 mg/dL) than in the roller pump group (32.25 mg/dL), p < 0.01. The CP has been used in ten pediatric patients undergoing cardiopulmonary bypass surgery. The patients' ages were from three to five years, and body weights were from 15 to 20 kg. Perfusion flow rates were maintained between 1.8 and 2.5 L/min, and bypass times were from 30 to 50 min. The rotation speeds were from 2000 to 2500 rpm. All the patients recovered smoothly, and no hemoglobinuria occurred.

Phitsanulok population: the highest incidence of hemoglobin E in the northern provinces of Thailand and PND counseling.

Phitsanulok is a province situated in the southern part of northern Thailand. Studies of hemoglobinopathies of 2,806 individuals during the period 1988-1990 showed an overall incidence of hemoglobinopathies of 38.89%, with HbE as high as 25% which is the highest incidence of HbE in the North of Thailand. Buddhachinaraj Hospital conducted a maternal screening study on 1,015 pregnant women in 1991 as part of a prevention/control program and found that 22.56% (229 women) had hemoglobinopathies. Of those, 102 (44.54%) individuals (83.33% HbE heterozygotes and 8.82% HbE homozygotes) with their spouses participated in a prenatal diagnosis (PND) counseling program; 100% of the females and 96% of the male were willing to accept PND; 71% of the females and 75.6% of the males had no moral objection in PND.

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.

Swine as a model for cardiovascular research: improved cardiopulmonary bypass techniques.

A large-animal model is essential for the assessment of functional parameters in cardiovascular surgical research. To date the canine model has been used successfully because of its availability and tolerance to cardiopulmonary bypass. However, because of decreased availability and increased cost, an alternative animal model is now needed. The swine model has been used in experimental cardiac procedures, but complications during cardiopulmonary bypass have presented a formidable challenge. These complications include enormous fluid shifts from the vascular bed, increased metabolic acidosis, and marked hemoglobinuria. To eliminate these deleterious complications within the swine model, a number of technical alterations were achieved. The priming solution used for the extracorporeal circuit was altered to consist of 1000 mL lactated Ringer's solution. 500 mL 20% mannitol, 500 mL 6% dextran in 5% detrose solution. 50 mEq sodium bicarbonate, and 10,000 IU heparin. The extracorporeal circuit employed the use of membrane oxygenation. Three different blood flow rates (150, 175, and 200 mL/kg min-1) were studied. We conclude that the optimum blood flow rate for cardiopulmonary bypass in swine is in the range of 175-200 mL/kg min-1. Membrane oxygenation results in less damage to blood during cardiopulmonary bypass. The asanguinous hyperosmolar priming solution is beneficial for cardiopulmonary bypass in swine to greatly reduce fluid shifts, prevent metabolic acidosis, and eliminate hemoglobinuria.