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Intestinal Blood Flow in Patients With Chronic Heart Failure: A Link With Bacterial Growth, Gastrointestinal Symptoms, and Cachexia
Study Questions:
What is the role of arterial intestinal blood flow in juxtamucosal bacterial growth, gastrointestinal (GI) symptoms, and cachexia in systolic heart failure (HF)?
Methods:
The study cohort was comprised of 65 systolic HF patients (left ventricular ejection fraction ≤40%) and 25 controls; 12 patients had cachexia. The study investigators used ultrasound to measure intestinal blood flow and to determine thickness of the bowel wall. They documented gastrointestinal symptoms and measured serum lipopolysaccharide (LPS) antibodies. Fluorescence in-situ hybridization was used to study bacteria from stool and juxtamucosal bacteria from biopsy samples obtained during sigmoidoscopy.
Results:
The investigators found that systolic HF patients had a 30-43% reduced mean systolic blood flow in the superior and inferior mesenteric arteries (SMA and IMA) and celiac trunk, compared with the controls (all p < 0.007). HF patients with cachexia had the lowest blood flow (p < 0.002). Lower blood flow in SMA and celiac trunk correlated with HF severity (all p < 0.04). Patients had more feelings of repletion, flatulences, intestinal sounds, and burping (all p < 0.04). Burping and nauseas/vomiting were most severe in cachexia (p < 0.05). Patients with lower celiac trunk blood flow had more abdominal discomfort and immunoglobulin A-anti-LPS (r = 0.76, p < 0.02). They found that anti-LPS-response correlated with increased growth of juxtamucosal and not stool bacteria. Patients with intestinal sounds had greater bowel wall thickness of sigmoid/descending colon suggestive for edema contributing to GI symptoms (p < 0.05). Using multivariable regression, the investigators found that lower blood flow in the SMA, and celiac trunk (p < 0.04) and IMA (p = 0.056) correlated with the presence of cardiac cachexia.
Conclusions:
The study authors concluded that reduced intestinal blood flow accompanies systolic HF. In cardiac cachexia, the reduction in intestinal blood flow is accompanied by GI symptoms and juxtamucosal bacterial growth.
Perspective:
This is an important study because it suggests that the mechanism of cardiac cachexia in systolic HF is due to impaired intestinal blood flow and accompanying changes in intestinal flora. The next step would be to determine whether: 1) altering splanchnic hemodynamics with somatostatin antagonists will influence cardiac cachexia, 2) altering intestinal bacterial flora with probiotics will improve outcomes, and 3) the obesity paradox can be explained by altered bacterial flora in systolic HF patients.
Keywords: Nausea, Biopsy, Edema, Mesenteric Artery, Inferior, Fluorescence, Bacteria, Heart Failure, Cachexia, Stroke Volume, Obesity, Flatulence
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