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Abstract Objectives This study aimed to investigate the procedural characteristics, efficacy, and safety of atrioventricular junction (AVJ) ablation for atrial tachyarrythmia (AT) in patients with congenital heart disease (CHD). Background Although AVJ ablation is an established treatment option for intractable AT in the general population, there is no existing data on this treatment in patients with CHD. Methods Data were analyzed from an observational, retrospective, multicenter cohort, initiated jointly by the Pediatric and Congenital Electrophysiology Society and the International Society of Adult Congenital Heart Disease. Eleven centers contributed baseline, procedural and longitudinal data, including vital status, echocardiographic data, QRS duration, and NYHA class. Outcomes were assessed at early (3 months-1 year), and late follow-up (≥2 years) after AVJ ablation. Results A total of 66 patients (46.7 ± 20.2 years) underwent 71 AVJ ablations. In total, 58.5% had moderate or complex CHD, including 17.1% patients with a systemic RV or single ventricular circulation. The cumulative AVJ ablation success rate was 98.5%. An abnormal location of the atrioventricular conduction pathway was successfully targeted in 20.0% of the patients, which was significantly more common in patients with complex CHD compared to moderate or mild CHD (44.4%, 15.8%, and 3.6%, respectively; both P<0.05). Thirty-six patients (54.5%) underwent primary pacemaker implantation as part of the ‘pace and ablate’ strategy; final pacing modes were VVI pacing in 60.9%, and CRT/CSP in 39.1%. The transplant-free survival rates at 2, 5 and 10 years after AVJ ablation were 91.5%, 84.3%, and 69.0%, respectively. The acute and long-term complication rates were 3.0% and 13.6%, respectively. Conclusions AVJ ablation can be successfully performed in CHD patients with a high acute success rate and low complication rate. Anatomical challenges were common, which underscores the need for careful planning and operator experience. Given the acceptable long-term survival, these findings support the consideration of a ‘pace and ablate’ strategy in CHD patients with intractable AT.

Background The objective of this international multicenter study was to investigate both early and late outcomes of cardiac resynchronization therapy (CRT) in patients with a systemic right ventricle (SRV) and to identify predictors for congestive heart failure readmissions and mortality. Methods and Results This retrospective international multicenter study included 13 centers. The study population comprised 80 adult patients with SRV (48.9% women) with a mean age of 45±14 (range, 18–77) years at initiation of CRT. Median follow‐up time was 4.1 (25th–75th percentile, 1.3–8.3) years. Underlying congenital heart disease consisted of congenitally corrected transposition of the great arteries and dextro‐transposition of the great arteries in 63 (78.8%) and 17 (21.3%) patients, respectively. CRT resulted in significant improvement in functional class (before CRT: III, 25th–75th percentile, II–III; after CRT: II, 25th–75th percentile, II–III; P =0.005) and QRS duration (before CRT: 176±27; after CRT: 150±24 milliseconds; P =0.003) in patients with pre‐CRT ventricular pacing who underwent an upgrade to a CRT device (n=49). These improvements persisted during long‐term follow‐up with a marginal but significant increase in SRV function (before CRT; 30%, 25th–75th percentile, 25–35; after CRT: 31%, 25th–75th percentile, 21–38; P =0.049). In contrast, no beneficial change in the above‐mentioned variables was observed in patients who underwent de novo CRT (n=31). A quarter of all patients were readmitted for heart failure during follow‐up, and mortality at latest follow‐up was 21.3%. Conclusions This international experience with CRT in patients with an SRV demonstrated that CRT in selected patients with SRV dysfunction and pacing‐induced dyssynchrony yielded consistent improvement in QRS duration and New York Heart Association functional status, with a marginal increase in SRV function.

The force within a muscle may be assessed using intramuscular pressure measurements (IMP). However, a limiting factor in implementing this technology in the clinic is the observed variability of IMP measurements. The variability may be due in part to the flow of interstitial fluid. The objective of this study was to develop a technique for tracking interstitial fluid flow during muscle lengthening using fluorescent microspheres. Additionally, the effect of microsphere diameter on dispersion was evaluated. Fluorescent microspheres were injected into the rat tibialis anterior (TA) either before (right limb) or after (left limb) lengthening to 10% strain (n = 5). To help discriminate the effects of microsphere size, 10 µl of microspheres (0.25% by volume) were injected simultaneously: 0.1 µm in sky blue and 0.2 µm in yellow green. Once frozen, 20 µm muscle cross‐sections were stained and imaged using confocal microscopy to evaluate the microsphere's axial dispersion as a percent of muscle length. The microsphere dispersion was normalized to the muscle length. The fluorescent microspheres flowed with the interstitial fluid and did not penetrate the muscle fiber. There was significantly greater microsphere dispersion with passive strain (p‐value > 0.01) for lengthened samples (31±7%) compared to static samples (17±9%). Dispersion did not differ for the two bead sizes. In conclusion, this illustrates the microspheres track the interstitial fluid and passive lengthening results in additional dispersion. Supported by NIH under award number R01HD31476 and T32HL105355.

ABSTRACTThe current method of measuring arthrofibrosis in live rabbits is critically limited. Specifically, this method involves radioactive fluoroscopy, error‐prone goniometric measurements, and static joint angle outcomes that fail to approximate the compliance of tissues surrounding the joint. This study aims to validate a novel method of capturing the compliance of contracted tissues surrounding the joint without the use of fluoroscopy or animal sacrifice. Surgically induced contractures of one‐hundred and eight rabbits were measured using the current standard of contracture measurement (a pulley system) as well as a newly designed dynamic load cell (DLC) device. The DLC device was highly reliable when compared to the pulley system (r = 0.907, p < 0.001). Finally, the DLC device produced joint stiffness hysteresis curves capable of approximating the compliance of stiff joint tissues, ultimately calculating a mean joint stiffness of 1.57 ± 1.31 N · m · rad−1 (range, 0.33–6.37 N · m · rad−1). In conclusion, the DLC device represents a valid method for measuring joint contractures. Further, the DLC device notably improves current techniques by introducing the capacity to approximate the compliance of contracted tissues in living rabbits. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2186–2192, 2018.

Abstract Quantitative evaluation of passive tension in a muscle is important in tendon transfer surgeries, however, currently appropriate intraoperative measurement techniques are lacking. Objective : Intramuscular pressure (IMP) is explored as an application to access force. Approach : The tibialis anterior (TA) in New Zealand white rabbits ( n = 9) was used to test the hypothesis of a strong correlation between the IMP, muscle force, and length. This study also helped to develop intraoperative techniques for future human studies evaluating various insertion techniques (parallel versus perpendicular). Main results : The Pearson correlation between IMP and force for all trials was 0.74 ± 0.30. Separating out the parallel insertion from the perpendicular insertion revealed a significantly higher correlation for parallel, 0.91 ± 0.13 versus 0.56 ± 0.32. Significance : These data indicate IMP sensors can be used to assess force in a single muscle and the parallel insertion method should be used. New findings • What is the central question of this study? Successful outcomes of tendon and muscle transfers depend on proper muscle tension. A near linear relationship has been seen between muscle force and intramuscular pressure. This study aims to develop an intraoperative technique for assessing passive muscle tension using intramuscular pressure. • What is the main finding and its importance? The findings from this study reveal a high correlation between pressure and passive tension in a single muscle. The techniques developed in this study will allow the translation to a human model. The work will help to improve surgical outcomes and aim to retain muscle strength in the patient following procedures such as tendon and muscle transfers.

ABSTRACTIntroductionRegional variability in interstitial fluid pressure confounds use of intramuscular pressure measurement to assess muscle force. It is hypothesized that interstitial flow is dependent on intramuscular pressure. The goal of this study was to assess the feasibility of using fluorescent microspheres to evaluate movement of interstitial fluid in skeletal muscle.MethodsTwo diameters of fluorescent microspheres were injected into the rat tibialis anterior during both static (n = 6) and passively lengthened (10% strain) experimental conditions (n = 6). Microsphere dispersion was evaluated using confocal imaging of transverse muscle sections.ResultsFluorescent microspheres tracked interstitial fluid while not penetrating the muscle fiber. When compared with the static condition, significantly greater dispersion (P = 0.003) was seen with passively lengthened conditions (17 ± 9% vs. 31 ± 7%, respectively). Dispersion did not differ for the 2 microsphere sizes (P = 0.811).ConclusionsFluorescent microspheres track movement of interstitial fluid, and dispersion is dependent on passive lengthening. Muscle Nerve 54: 444–450, 2016