Adult Acute Rheumatic Fever: A Rare Case Presenting with Left Bundle Branch Block

In contrast to the more common electrocardiographic patterns seen in acute rheumatic fever, such as first-degree heart block, the appearance of left bundle branch block is rare. An adult patient with acute rheumatic fever presented with left bundle branch block on admission, subsequently had sudden cardiac arrest. She was resuscitated successfully and required temporary pacing. An echocardiogram and radionuclide ventriculography were compatible with interventricular septal involvement in the rheumatic carditis. After 20 days of steroid therapy, the left bundle branch block pattern of the electrocardiogram disappeared. A possible mechanism for the development of complete heart block in acute rheumatic fever is discussed. It is suggested that patients with acute rheumatic carditis who have electrocardiographic manifestations of prolonged P-R interval and left bundle branch block should be managed with prophylactic pacing.     

Paroxysmal Severe Mitral Regurgitation

ObjectiveTo investigate the clinical presentation, pathophysiology, and treatment for "paroxysmal severe mitral regurgitation" (MR), which is an underappreciated cause of heart failure with preserved left ventricular ejection fraction.MethodsWe retrospectively reviewed cases of transient severe MR that were evaluated at Mayo Clinic in Rochester, Minnesota, between January 1, 2006, and December 31, 2019. Paroxysmal severe MR was defined as the appearance of transient severe MR in patients with mild MR at rest, normal left ventricle (LV) size, left ventricular ejection fraction greater than 40%, and absence of obstructive coronary artery disease.ResultsWe identified 6 patients (5 women) with a median age of 68 years. There were 3 distinct mechanisms of paroxysmal severe MR, which we labeled types 1, 2, and 3. Type 1 MR was caused by LV dyssynchrony from a rate-dependent left bundle branch block, which led to apical leaflet tenting and incomplete coaptation. Type 2 MR occurred from mitral annular dilatation during maneuvers that increased left-sided volume. Type 3 MR was caused by coronary artery vasospasm with apical leaflet tenting. Treatments varied depending on the underlying cause and included cardiac resynchronization therapy for type 1, surgical valve replacement for type 2, and medical therapy for type 3.ConclusionParoxysmal severe MR is a rare cause of heart failure in patients with preserved LV function. We have identified 3 distinct mechanisms that can lead to this dynamic process, with treatments varying based on the underlying cause.     

3DCubeT2WIMRI测量前交叉韧带双束结构的研究

目的:应用3D Cube T2WI核磁共振成像斜冠状位重建图像显示前交叉韧带(anterior cruciate ligament,ACL)双束结构,并测量其解剖指标.方法:19例经临床确诊的健康志愿者行双膝关节3D Cube T2加权MRI检查.分别在斜冠状位重建图像测量前内侧束(anteromedial bundle,AMB)和后外侧束(posterolateral bundle,PLB)的股骨止点、胫骨止点宽度、韧带长度及走行角度.应用Mann-Whitney test比较AMB和PLB的长度,止点宽度和走行角度在不同性别间的差异,并进一步对测量所产生的差异进行Logistic回归分析.结果:AMB和PLB的平均长度分别为31.01mm和25.38mm;股骨止点平均宽度为10.6mm和9.47mm;胫骨止点平均宽度为11.28mm和8.49 mm;走行角度平均为72.01°和64.97°.AMB、PLB的股骨止点、胫骨止点宽度及走行角度在不同性别间无显著性差异(P＞0.05).然而,男性AMB和PLB韧带长度大于女性(P＜0.05);经Logistic回归分析显示这种差异与身高成正相关(P＜0.05).结论:各向同性3D Cube T2加权序列及其重建图像所显示的ACL双束结构;以及股骨止点宽度、胫骨止点宽度、长度及走行角度的精确测量结果,可为个性化制定ACL双束重建术方案提供有价值的依据.     

Characterization of Responder Profiles for Cardiac Resynchronization Therapy through Unsupervised Clustering of Clinical and Strain Data

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肘关节内侧副韧带前束重建的生物力学研究

目的通过测量肘关节内侧副韧带(medial collateral ligament,MCL)前束生物力学指标,探讨前束完整及重建后对肘关节外翻稳定性的影响,评价采用人工肌腱、界面螺钉重建MCL前束疗效。方法成人完整上肢标本12具,男8具,女4具;左、右侧各6具;制成肘关节"骨-韧带"标本。采用生物力学及压敏胶片测量方法,分别测量MCL前束完整(对照组)及使用人工肌腱、界面螺钉重建后(实验组)肘关节屈曲0、30、60、90°时关节外翻松弛度、肱尺关节受力面积及肘关节内压强。结果两组在肘关节不同屈曲角度下,组内及组间关节松弛度比较,差异均无统计学意义(P>0.05)。除肘关节屈曲0°时两组肘关节压强小于其余屈曲角度(P<0.05),及对照组小于实验组(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。除对照组内肘关节屈曲0°时肱尺关节受力面积大于其余屈曲角度(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。结论 MCL前束对维持肘关节外翻稳定性具有重要意义,金属界面螺钉加人工肌腱重建后可即刻恢复内侧稳定。     

Septal Flash-like Motion of the Earlier Activated Ventricular Wall Represents the Pathophysiology of Mechanical Dyssynchrony in Single-Ventricle Anatomy

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Noninvasive recording of His bundle electrograms using vectorial leads system

His bundle electrograms were recorded in 8 rats by a signal averaging technique using the Takayasu vectorial lead system. Animals were anesthetized and placed in the prone position. The polarity of three orthogonal leads were: the X axis, from right to left; the Y axis, from top to bottom; the Z axis, from back to front. Potentials from the X, Y, and Z leads were amplified by 20,000 with high-pass 12 dB/octave filtering at 80 Hz, and signal averaging of 2000 beats was performed at a sampling interval of 100 microseconds. The His bundle potential could be clearly defined in all 8 rats. The mean amplitude of the His potential was larger in the X-axis (23.6 +/- 9.2 mu V) or the Y-axis (28.4 +/- 14.5 mu V) than the Z-axis lead (11.5 +/- 8.6 mu V). Directions of the His potential vectors were to the left in 5 of 8 rats (62.5%), to the caudal in 4 of 6 rats (66.7%), and to the dorsal site in 6 of 8 rats (75.0%). This vectorial lead system, devised in accordance with McFee and Johnston's theory on lead field, was useful for recording His bundle electrograms.     

Minimizing Permanent Pacemaker Following Repositionable Self-Expanding Transcatheter Aortic Valve Replacement

ObjectivesThis study sought to minimize the risk of permanent pacemaker implantation (PPMI) with contemporary repositionable self-expanding transcatheter aortic valve replacement (TAVR).BackgroundSelf-expanding TAVR traditionally carries a high risk of PPMI. Limited data exist on the use of the repositionable devices to minimize this risk.MethodsAt NYU Langone Health, 248 consecutive patients with severe aortic stenosis underwent TAVR under conscious sedation with repositionable self-expanding TAVR with a standard approach to device implantation. A detailed analysis of multiple factors contributing to PPMI was performed; this was used to generate an anatomically guided MInimizing Depth According to the membranous Septum (MIDAS) approach to device implantation, aiming for pre-release depth in relation to the noncoronary cusp of less than the length of the membranous septum (MS).ResultsRight bundle branch block, MS length, largest device size (Evolut 34 XL; Medtronic, Minneapolis, Minnesota), and implant depth > MS length predicted PPMI. On multivariate analysis, only implant depth > MS length (odds ratio: 8.04; 95% confidence interval: 2.58 to 25.04; p < 0.001) and Evolut 34 XL (odds ratio: 4.96; 95% confidence interval: 1.68 to 14.63; p = 0.004) were independent predictors of PPMI. The MIDAS approach was applied prospectively to a consecutive series of 100 patients, with operators aiming to position the device at a depth of < MS length whenever possible; this reduced the new PPMI rate from 9.7% (24 of 248) in the standard cohort to 3.0% (p = 0.035), and the rate of new left bundle branch block from 25.8% to 9% (p < 0.001).ConclusionsUsing a patient-specific MIDAS approach to device implantation, repositionable self-expanding TAVR achieved very low and predictable rates of PPMI which are significantly lower than previously reported with self-expanding TAVR.