Anatomical characteristics of the membranous septum are predictive of pacemaker requirement in patients undergoing transcatheter aortic valve replacement.

PURPOSE: We aimed to study the characteristics of the membranous septum (MS) and its relationship with the aortic valve (AoV) and aortic annulus (AA) in patients who required PPM post-TAVR. METHODS: We performed a retrospective case-control study of 144 patients undergoing TAVR from 2016 to 2018. Thirty-four patients, requiring PPM implantation, were compared with 34 matched controls who did not require pacing. The total MS length, supra-annular MS (SA-MS) length, infra-annular MS (IA-MS) length, angle between the plane of the AA and MS (AA-MS), and degree of AoV calcifications (AVC) were obtained from preoperative CT. AoV prosthesis implantation depth was obtained from intra-operative fluoroscopy. RESULTS: There were no significant differences in valve type (self-expandable: 23 cases vs 25 controls, and balloon-expandable: 11 vs 9, p = 0.79), degree of AVC (0.65 cm3 vs 0.82 cm3, p = 0.62), or implantation depth (7.76 mm vs 7.28 mm, p = 0.83). Compared to controls, there was no difference in total MS length (6.68 mm vs 6.06 mm, p = 0.97), but the IA-MS was significantly shorter (3.64 mm vs 4.56 mm, p = 0.02) and the SA-MS was significantly longer (2.73 mm vs 1.67 mm, p = 0.02) in patients requiring PPM. Patients requiring PPM also had a larger AA-MS angle (103.5° vs 96.7°, p = 0.01). CONCLUSION: The position of the MS with respect to the AA and MS distance below the annular plane were more closely associated with post-TAVR conduction abnormalities requiring PPM than the absolute length of the MS. Patients undergoing TAVR with such anatomy have a higher risk of requiring PPM and should be monitored for developing these complications.

Acute Limb Ischemia Caused by Inadvertent Arterial Drug Self-Injection: A Case Report.

BACKGROUND A predictable consequence of long-term injection drug use is the destruction of the native venous system; as a consequence, people who inject drugs may eventually move to injection into skin and subcutaneous tissue, wounds, muscles, and arteries. These practices put people who inject drugs at risk for injection-related soft-tissue infection, vascular damage, ischemia, and compartment syndrome, all of which have overlapping presenting symptoms. CASE REPORT A 35-year-old man who injects drugs presented with foot swelling and discoloration initially concerning for necrotizing fasciitis or compartment syndrome. After progression despite appropriate antimicrobial and surgical treatment for soft-tissue infection, he was diagnosed with arterial insufficiency and resultant distal ischemia. This diagnosis was discovered only after obtaining additional history of the patient's drug use practices. Just prior to his symptoms, he had unintentionally injected a formed thrombus into his dorsalis pedis artery. CONCLUSIONS Intra-arterial injection of drugs can cause ischemia through a variety of mechanisms, including direct vessel trauma, arterial spasm, toxicity from the drug of abuse or an adulterant, embolism of particulate matter, and as proposed here, direct injection of preformed thrombus. Medical providers should be aware of the steps of injection drug use and their associated risks so that they can ask appropriate questions to focus their differential diagnosis, increase their understanding of common or current local injection practices, and develop rapport with the patient. Patient education on safe injection techniques may also reduce the risk of serious complications.