Role of adenosine monophosphate deaminase-1 gene polymorphism in patients with congestive heart failure (influence on tumor necrosis factor-alpha level and outcome).

The Cytosin-->thymidin transition at codon 12 of the adenosine monophosphate deaminase-1 (AMPD1) gene results in a complete loss of its catalytic activity. The increased conversion of adenosine monophosphate to adenosine, which in turn attenuates the expression of tumor necrosis factor-alpha (TNF-alpha) expression, has been suggested as a putative mechanism for prolonged survival in patients with congestive heart failure (CHF) carrying the mutant AMPD1 allele. Therefore, the impact of this polymorphism on circulatory TNF-alpha concentrations and outcome in patients with CHF should be studied. The AMPD1 genotype of each patient with CHF (n = 90; idiopathic dilated cardiomyopathy n = 53; coronary artery disease n = 20; other n = 17) was determined by direct sequencing. Serum TNF-alpha concentrations were measured by enzyme-linked immunosorbent assay. We found 66 patients (75.6%) to be homozygous for the wild-type allele (AMPD1 +/+), and 20 patients (22.2%) were heterozygous and 2 were homozygous (2.2%) for the mutant AMPD1 allele (AMPD1 +/- or -/-). TNF-alpha serum concentrations were 4.2 +/- 2.0 pg/ml for the AMPD1 +/+ genotype and 5.3 +/- 2.9 pg/ml for the AMPD1 +/- and -/- genotypes (p = 0.045). A downregulation of TNF-alpha in patients carrying the mutant allele could therefore be not detected. However, Kaplan-Meier analysis demonstrated a significantly prolonged survival without heart transplantation or revival from sudden death in the AMPD1 +/- & -/- group (p = 0.020). Multivariate analysis identified the AMPD1 wild-type genotype as an independent risk factor (odds ratio 9.34, 95% confidence interval 1.78 to 48.96). The mutant AMPD1 allele, in the context of CHF, is associated with a prognostic benefit. The underlying mechanism of TNF-alpha is unrelated.

Studies on intragastric PCO2 at rest and during exercise as a marker of intestinal perfusion in patients with chronic heart failure.

AIMS: The aim of this study was to investigate mesenteric ischaemia by determining intragastric PCO(2) (iPCO(2)) with gastric tonometry during rest and exercise stress testing in patients with chronic heart failure (CHF). In CHF inflammatory immune activation is hypothesized to result from a chronic endotoxin challenge due to bacterial translocation of hypoperfused intestinal mucosa. METHODS AND RESULTS: In 10 patients with CHF and ten healthy controls a tonometry catheter was inserted into the stomach. IPCO(2) was measured at rest and during bicycle exercise every 5 min. At rest arterial pCO(2) (aPCO(2)), intragastric pCO(2) (iPCO(2)) and the intragastric/arterial gap did not differ between patients and controls. During low level exercise (25 W), patients showed an increase in iPCO(2) compared to resting iPCO(2), whereas controls did not show an increase in iPCO(2) (change in iPCO(2): 12+/-2% vs. 1+/-0.4%, P<0.001). In CHF, iPCO(2) during peak exercise was 25+/-3% higher than at rest, compared to controls (increase 2+/-1, P<0.0001). CONCLUSIONS: Patients with CHF already at low level exercise develop an increase in iPCO(2). This is likely to reflect hypoperfusion of the intestinal mucosa, which may contribute to the development of bacterial translocation.