Fatal Case of a Contained Ruptured of the Infrarenal Aorta due to Simultaneous Primary Aortocaval Fistula and Aortoenteric Fistula

We report an extremely rare case of primary aortocaval fistula with simultaneous development of an aortoenteric fistula in a 68-year-old man. The patient developed under oral anticoagulation a spontaneous intracaval aortic rupture. An emergency intervention was performed with a covering of the fistula with an aorto-uniiliac stent graft and a femoro-femoral crossover bypass. One week later, the patient was transferred to our institution with the diagnosis of a psoas abscess and a suspected concomitant aortoenteric fistula. We performed a complete explantation of the endograft and implanted it after extensive debridement an aortobiiliac bypass, made of bovine pericardium. The postoperative course was complicated, first by bleeding from the left iliac anastomosis, and then by bleeding from the proximal aortic anastomosis. The entire graft was explanted and an axillo-femoral bypass was implanted. The patient then developed a multi-organ failure and died 3 months later. If possible, an extended surgical debridement and resection of all infected tissue with in situ reconstruction is the gold standard. However, with this therapy, there is still a high risk of reinfection. Long-term antibiotic management is mandatory.

Decreased Substrate Stiffness Promotes a Hypofibrotic Phenotype in Cardiac Fibroblasts

A hypofibrotic phenotype has been observed in cardiac fibroblasts (CFs) isolated from a volume overload heart failure model, aortocaval fistula (ACF). This paradoxical phenotype results in decreased ECM synthesis despite increased TGF-β presence. Since ACF results in decreased tissue stiffness relative to control (sham) hearts, this study investigates whether the effects of substrate stiffness could account for the observed hypofibrotic phenotype in CFs isolated from ACF. CFs isolated from ACF and sham hearts were plated on polyacrylamide gels of a range of stiffness (2 kPa to 50 kPa). Markers related to cytoskeletal and fibrotic proteins were measured. Aspects of the hypofibrotic phenotype observed in ACF CFs were recapitulated by sham CFs on soft substrates. For instance, sham CFs on the softest gels compared to ACF CFs on the stiffest gels results in similar CTGF (0.80 vs. 0.76) and transgelin (0.44 vs. 0.57) mRNA expression. The changes due to stiffness may be explained by the observed decreased nuclear translocation of transcriptional regulators, MRTF-A and YAP. ACF CFs appear to have a mechanical memory of a softer environment, supported by a hypofibrotic phenotype overall compared to sham with less YAP detected in the nucleus, and less CTGF and transgelin on all stiffnesses.

Renal Sympathetic Denervation Attenuates Congestive Heart Failure in Angiotensin II-Dependent Hypertension: Studies with Ren-2 Transgenic Hypertensive Rats with Aortocaval Fistula

<b><i>Objective:</i></b> We examined if renal denervation (RDN) attenuates the progression of aortocaval fistula (ACF)-induced heart failure or improves renal hemodynamics in Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension. <b><i>Methods:</i></b> Bilateral RDN was performed 1 week after creation of ACF. The animals studied were ACF TGR and sham-operated controls, and both groups were subjected to RDN or sham denervation. In separate groups, renal artery blood flow (RBF) responses were determined to intrarenal ANG II (2 and 8 ng), norepinephrine (NE) (20 and 40 ng) and acetylcholine (Ach) (10 and 40 ng) 3 weeks after ACF creation. <b><i>Results:</i></b> In nondenervated ACF TGR, the final survival rate was 10 versus 50% in RDN rats. RBF was significantly lower in ACF TGR than in sham-operated TGR (6.2 ± 0.3 vs. 9.7 ± 0.5 mL min⁻¹ g⁻¹, <i>p</i> &#x3c; 0.05), the levels unaffected by RDN. Both doses of ANG II decreased RBF more in ACF TGR than in sham-operated TGR (−19 ± 3 vs. −9 ± 2% and −47 ± 3 vs. −22 ± 2%, <i>p</i> &#x3c; 0.05 in both cases). RDN did not alter RBF responses to the lower dose, but increased it to the higher dose of ANG II in sham-operated as well as in ACF TGR. NE comparably decreased RBF in ACF TGR and sham-operated TGR, and RDN increased RBF responsiveness. Intrarenal Ach increased RBF significantly more in ACF TGR than in sham-operated TGR (29 ± 3 vs. 17 ± 3%, <i>p</i> &#x3c; 0.05), the changes unaffected by RDN. ACF creation induced marked bilateral cardiac hypertrophy and lung congestion, both attenuated by RDN. In sham-operated but not in ACF TGR, RDN significantly decreased mean arterial pressure. <b><i>Conclusion:</i></b> The results show that RDN significantly improved survival rate in ACF TGR; however, this beneficial effect was not associated with improvement of reduced RBF or with attenuation of exaggerated renal vascular responsiveness to ANG II.

A rare case of paradoxical pulmonary embolism in spontaneous aortocaval fistula

Aortocaval fistula (ACF) is a rare complication of abdominal aortic aneurysm (AAA), occurring in less than 1% of all AAAs. Paradoxical embolism can rarely be associated with ACF, pulmonary embolism may originate from dislodgment of thrombotic material from the AAA in the inferior vena cava (IVC) through the ACF. We report a case of a patient admitted to the emergency department with abdominal pain and shortness of breath who immediately underwent thoraco-abdominal CT. Imaging allowed a prompt pre-operative diagnosis of an ACF between an AAA and the IVC, also identifying CT signs of right heart overload and the presence of a paradoxical pulmonary embolism.