Gastrointestinal bleeding and pro-angiogenic shift in the angiopoietin axis with continuous flow left ventricular assist device implantation.

BACKGROUND: Gastrointestinal bleeding (GIB) affects up to 40% of continuous-flow left ventricular assist device (CF-LVAD) recipients. A higher risk of GIB is seen in CF-LVAD recipients with lower device pulsatility without a known mechanism. One hypothesis is that the novel hemodynamics in CF-LVAD recipients affect angiogenesis signaling. We aimed to (1) measure serum levels of angiopoietin (Ang)-1, Ang-2, and VEGF-A in CF-LVAD recipients with and without GIB and in healthy controls and (2) evaluate correlations of those levels with hemodynamics. METHODS: We recruited 12 patients with CF-LVADs (six who developed GIB after device implantation) along with 12 age-matched controls without heart failure or GIB and measured Ang-1, Ang-2, and VEGF-A levels in serum samples from each patient. RESULTS: CF-LVAD recipients had significantly higher Ang-2 and lower Ang-1 levels compared to controls with no difference in VEGF-A levels. CF-LVAD recipients with GIB had lower Ang-1 levels than those without GIB. There were trends for pulse pressure to be positively correlated with Ang-1 levels and negatively correlated with Ang-2 levels in CF-LVAD recipients with no correlation observed in healthy controls. CONCLUSION: CF-LVAD recipients demonstrated a shift toward a pro-angiogenic phenotype in the angiopoietin axis that is significantly associated with GIB and may be linked to low pulse pressure.

Factitious Gastrointestinal Bleeding: A Case Series and Review.

Factitious gastrointestinal bleeding (GIB) is a manifestation of factitious disorder (FD) wherein patients feign GIB in the absence of external gain. As it can be a challenging diagnosis to make, factitious GIB often leads to multiple tests, exposure to contrast agents and radiation, invasive endoscopic and surgical procedures, an increased risk of iatrogenic complications, and increased healthcare costs. Patients who feign GIB often demonstrate characteristic behaviors that may go unnoticed unless they are explicitly addressed. We report a series of patients admitted to our institution for further evaluation of obscure overt GIB with an eventual diagnosis of factitious GIB and review of the epidemiology and development of FD, a diagnostic approach to factitious GIB, and current management strategies.

Association of Pulsatility with Gastrointestinal Bleeding in a Cohort of HeartMate II Recipients.

Gastrointestinal bleeding (GIB) is common in patients with continuous-flow left ventricular assist devices (CF-LVADs) possibly because of changes in blood flow. We aimed to test the hypothesis that a low pulsatility index (PI) is associated with an increased hazard of overt GIB in patients with CF-LVADs. We conducted a retrospective cohort study of patients who had a HeartMate II (HMII) CF-LVAD implanted at our center. The study end-point was the first overt GIB causing or occurring during a hospitalization between 6 days and 6 months after HMII implantation. HMII PI was recorded at 48 hours and at 1, 3, and 6 month intervals after implantation. We analyzed the associations of PI and clinical variables with the hazard of overt GIB. Ninety-five patients met eligibility criteria. PI ranged from 2.5 to 5.9 (low PI < 4.15 and high PI ≥ 4.15 on the basis of receiver operating characteristic curve analysis). Seventeen (18%) patients experienced overt GIB. In a multivariable model, only lower baseline hemoglobin was a significant predictor of an increased hazard of overt GIB. After adjusting for the baseline hemoglobin, low PI was independently associated with an increased hazard of overt GIB in our cohort of HMII recipients.

Utility of double-balloon enteroscopy in patients with left ventricular assist devices and obscure overt gastrointestinal bleeding.

Obscure overt gastrointestinal bleeding (OGIB) is a challenge in patients with left ventricular assist devices (LVADs). We evaluated the utility and safety of double-balloon enteroscopy (DBE) in patients with LVADs in an observational consecutive-patient cohort from a single tertiary referral center. Ten patients with LVADs underwent thirteen DBEs for obscure OGIB. The first OGIB event necessitating DBE occurred after a mean of 512 ± 363 days of LVAD support. All patients underwent DBE, eleven anterograde and two retrograde, with a mean insertion depth 176 ± 85 cm. Diagnostic yield was 69 % with the primary bleeding lesion most frequently found in the mid-bowel. The most common lesions were arteriovenous malformations. Therapeutic yield with argon plasma coagulation (APC), epinephrine injection, and/or hemoclip placement was 89 %. There were no procedure-related complications. DBE in patients with LVADs has good diagnostic yield and high therapeutic yield for obscure OGIB and is safe and well tolerated.

Platypnea-Orthodeoxia Syndrome: What Is the Driving Force?

A 69-year-old patient presented with episodic, acute hypoxia and an increasing oxygen requirement. His hemoglobin oxygenation reached its nadir in the 80% to 85% range as measured by pulse oximetry while he was sitting upright. Oxygenation would improve in this patient to percentages in the upper 90s when he was in the supine position. He was found to have a large secundum atrial septal defect with bidirectional intracardiac shunting, left hemidiaphragmatic dysfunction, a dilated ascending aorta and a prominent Eustachian valve. The patient was stabilized with oxygen therapy, and the cardiology service provided definitive treatment via percutaneous shunt closure with a septal occluder.

Formicine ants: An arthropod source for the pumiliotoxin alkaloids of dendrobatid poison frogs.

A remarkable diversity of bioactive lipophilic alkaloids is present in the skin of poison frogs and toads worldwide. Originally discovered in neotropical dendrobatid frogs, these alkaloids are now known from mantellid frogs of Madagascar, certain myobatrachid frogs of Australia, and certain bufonid toads of South America. Presumably serving as a passive chemical defense, these alkaloids appear to be sequestered from a variety of alkaloid-containing arthropods. The pumiliotoxins represent a major, widespread, group of alkaloids that are found in virtually all anurans that are chemically defended by the presence of lipophilic alkaloids. Identifying an arthropod source for these alkaloids has been a considerable challenge for chemical ecologists. However, an extensive collection of neotropical forest arthropods has now revealed a putative arthropod source of the pumiliotoxins. Here we report on the presence of pumiliotoxins in formicine ants of the genera Brachymyrmex and Paratrechina, as well as the presence of these ants in the stomach contents of the microsympatric pumiliotoxin-containing dendrobatid frog, Dendrobates pumilio. These pumiliotoxins are major alkaloids in D. pumilio, and Brachymyrmex and Paratrechina ants now represent the only known dietary sources of these toxic alkaloids. These findings further support the significance of ant-specialization and alkaloid sequestration in the evolution of bright warning coloration in poison frogs and toads.