Transthoracic echo-guided pacemaker implantation reduces fluoroscopic use in dogs.

Echocardiographic guidance provides an alternative method when fluoroscopy is unavailable, equipment or power failure of fluoroscopic equipment during a procedure occurs or to decrease radiation risk. Recently, transthoracic (TTE) and transesophageal echocardiography were reported as an alternative method to guide interventional procedures in dogs. Therefore, we hypothesized that TTE could be used as an alternative method to visualize endocardial leads during pacemaker implantation in dogs, largely avoiding the use of fluoroscopy. A prospective consecutive case series of pacemaker implantation was performed using TTE guidance. The endocardial lead was imaged by TTE during its intracardiac advancement until the lead tip was positioned at the right ventricular apex. Echocardiographic right parasternal views, optimized to visualize the pacing lead, were used, starting with a short axis image of the right atrium and ending with a long axis view of the right ventricle (RV) optimized to image the RV apex. Proper lead placement was confirmed by both capture threshold, impedance and fluoroscopy. Twenty-one pacemaker implantation procedures by TTE monitoring were successfully performed. The TTE guidance provided images of a quality sufficient to clearly monitor implantation in real-time and allowed for immediate corrections to pacing lead malpositioning or excessive looping. Fluoroscopy was used to confirm the correct placement of the lead that was guided echocardiographically in the initial three procedures, after which a single radiographic image (no cine-mode) was used to identify lead placement and redundancy in the remaining eighteen cases. Static imaging (radiography using the fluoroscope) was used to assess the proper lead redundancy in all procedures because this cannot be evaluated echocardiographically. Pacemaker leads were successfully implanted in the RV of dogs using TTE monitoring. A larger cases series is needed for validation of safety and effectiveness of TTE during this interventional procedure in dogs.

Transesophageal echocardiography as the sole guidance for occlusion of patent ductus arteriosus using a canine ductal occluder in dogs.

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) is usually performed by fluoroscopy alone or together with transesophageal echocardiography (TEE). Transthoracic echocardiography (TTE) guidance has been used for deployment of Amplatz Canine Ductal Occluder (ACDO), but sometimes is limited by suboptimal acoustic windows. Transesophageal echocardiography can overcome such issues and provides higher image resolution at the level of the great vessels. OBJECTIVES: To determine if TEE without fluoroscopy could be used to successfully perform ductal occlusion for the treatment of PDA in dogs. ANIMALS: Twenty client-owned dogs with PDA. METHODS: A prospective consecutive case series of PDA occlusion was performed using only TEE guidance. Dogs were positioned in right lateral recumbency and the TEE probe was positioned to visualize the descending aorta, PDA, and pulmonary artery. The guide wire, long introducer sheath, and ACDO were imaged by TEE to direct deployment. RESULTS: Ductal occlusion was performed successfully without need for fluoroscopy and without complications in 19 dogs. One dog required a second larger ACDO because of embolization of the first device 18 hours after positioning. CONCLUSIONS AND CLINICAL IMPORTANCE: We have demonstrated that TEE monitoring without concurrent fluoroscopy can guide each step of transcatheter ACDO embolization thereby providing an alternate method of visualization for this procedure. Use of TEE alone can reduce radiation exposure or is an option when fluoroscopy is not available, and, therefore, should be evaluated in a larger case series to better assess procedural failure rates.

Myosin-binding protein C DNA variants in domestic cats (A31P, A74T, R820W) and their association with hypertrophic cardiomyopathy.

BACKGROUND: Two mutations in the MYBPC3 gene have been identified in Maine Coon (MCO) and Ragdoll (RD) cats with hypertrophic cardiomyopathy (HCM). OBJECTIVE: This study examined the frequency of these mutations and of the A74T polymorphism to describe their worldwide distribution and correlation with echocardiography. ANIMALS: 1855 cats representing 28 breeds and random-bred cats worldwide, of which 446 underwent echocardiographic examination. METHODS: This is a prospective cross-sectional study. Polymorphisms were genotyped by Illumina VeraCode GoldenGate or by direct sequencing. The disease status was defined by echocardiography according to established guidelines. Odds ratios for the joint probability of having HCM and the alleles were calculated by meta-analysis. Functional analysis was simulated. RESULTS: The MYBPC3 A31P and R820W were restricted to MCO and RD, respectively. Both purebred and random-bred cats had HCM and the incidence increased with age. The A74T polymorphism was not associated with any phenotype. HCM was most prevalent in MCO homozygote for the A31P mutation and the penetrance increased with age. The penetrance of the heterozygote genotype was lower (0.08) compared with the P/P genotype (0.58) in MCO. CONCLUSIONS AND CLINICAL IMPORTANCE: A31P mutation occurs frequently in MCO cats. The high incidence of HCM in homozygotes for the mutation supports the causal nature of the A31P mutation. Penetrance is incomplete for heterozygotes at A31P locus, at least at a young age. The A74T variant does not appear to be correlated with HCM.