New insights into the clinical signs of supraventricular tachycardia: The “sign of lace‐tying”

Background

Supraventricular tachycardias (SVT) are a common arrhythmia therefore an accurate diagnosis is of clinical importance. Although an ECG performed during tachycardia greatly aids diagnosis, patient history and predisposing factors also improve diagnostic accuracy.

Methods

This prospective study included 100 consecutive patients undergoing electrophysiological study for SVT with the aim to reassess their clinical characteristics and describe frequent predisposing factors, such as the “sign of lace‐tying” that to our knowledge has not previously been reported. Each patient completed an extensive questionnaire (70 questions) during their hospital stay.

Results

Our series comprised: 67% of patients with atrioventricular nodal reentrant tachycardia (AVNRT); 24% with an accessory pathway; and 9% presented atrial tachycardia. Half of the population were male and 29% of the cohort presented hypertension. Syncope during tachycardia appeared in 15% of patients, dizziness in 52% and thoracic pain in 59%. We encountered a predisposing risk factor for SVT in 53% of cases; with 32% exhibiting an anteflexion of the trunk termed the “sign of lace‐tying.” Data also showed that younger patients tended to present AVRT and regular pounding in the neck appeared only in patients with AVNRT.

Conclusions

Overall, our study has highlighted the importance of considering clinical signs and patient characteristics both before and during SVT for the precise diagnosis of paroxysmal SVT. Furthermore, 32% of patients presented the “sign of lace‐tying” or body position change before SVT, implying a diagnosis of SVT.

     

Differential modulation of L-type Ca2+ current by SR Ca2+ release at the T-tubules and surface membrane of rat ventricular myocytes

We have characterized modulation of ICa by Ca2+ at the t-tubules (ie, in control cells) and surface sarcolemma (ie, in detubulated cells) of cardiac ventricular myocytes, using the whole-cell patch clamp technique to record ICa. ICa inactivation was significantly slower in detubulated cells than in control cells (27.1+/-7.8 ms, n=22, versus 16.4+/-7.9 ms, n=22; P<0.05). In atrial myocytes, which lack t-tubules, ICa inactivation was not changed by the treatment used to produce detubulation. In the presence of ryanodine or BAPTA, or when Ba2+ was used as the charge carrier, the rate of inactivation was not significantly different in control and detubulated cells. Frequency-dependent facilitation occurred in control cells but not in detubulated cells, and was abolished by ryanodine. These results suggest that Ca2+ released from the SR has a greater effect on ICa in the t-tubules than at the surface sarcolemma. This does not appear to be due to differences in local Ca2+ release from the SR, because the gain of Ca2+ release was not significantly different in control and detubulated cells. These data suggest that the t-tubules are a key site for the regulation of transsarcolemmal Ca2+ flux by Ca2+ release from the SR; this could play a role in altered Ca2+ homeostasis in pathological conditions. The full text of this article is available online at http://circres.ahajournals.org.     

Early‐onset hypoparathyroidism and chronic keratitis revealing APECED

Early diagnosis of potentially life‐threatening autoimmune polyendocrinopathy‐candidiasis‐ectodermal dystrophy (APECED) is crucial, but is often delayed due to the clinical heterogeneity of the disorder. Even in the absence of the classic disease triad of chronic mucocutaneous candidiasis, hypoparathyroidism, and adrenocortical insufficiency, a diagnosis of APECED should be considered in children who have hypoparathyroidism and chronic keratitis, with a past medical history showing a mild and transient Candida infection.     

Definition of left ventricular remodelling following ST-elevation myocardial infarction: a systematic review of cardiac magnetic resonance studies in the past decade

Heart Failure Reviews - An increase in left ventricular volumes between baseline and follow-up imaging is the main criteria for the quantification of left ventricular remodelling (LVR) after...     

Assessing hepatitis B virus resistance in vitro and molecular mechanisms of nucleoside resistance

The development of viral resistance to drugs can significantly reduce the efficacy of therapy for chronic hepatitis B virus (HBV) infection, slowing the rate of seroconversion, reversing previous gains in liver function and histology, and allowing disease progression. The efficacy of the nucleoside analogue lamivudine has been compromised by the development of viral resistance. Research into the mechanisms of nucleoside resistance has intensified and has included the development of new resistance assays. Resistance to lamivudine appears to be caused by the compound's structural features. Mutations are selected in HBV polymerase that can discriminate among the structural differences between lamivudine triphosphate and the natural substrate mimicked by lamivudine, dCTP, causing steric hindrance and reduced efficiency of incorporation of lamivudine but not the natural substrate. Unlike lamivudine, adefovir dipivoxil, an oral anti-HBV agent in late-stage development, has not been associated with HBV resistance, either in vitro or in vivo. One long-term clinical study has shown a lack of resistance to adefovir dipivoxil in patients treated for up to 136 weeks. In addition, adefovir dipivoxil is a nucleotide (rather than a nucleoside) analogue that exhibits no cross-resistance with lamivudine and is effective against lamivudine-resistant HBV. In one hypothesis, this lack of resistance has been attributed to the minimal flexible acyclic structure of adefovir that subverts resistance due to steric hindrance. By reducing the rate and frequency of development of drug resistance, adefovir dipivoxil and other new oral antiviral agents maximize the clinical advantages of long-term sustained viral suppression (HBV DNA reduction) to achieve lasting therapeutic benefits.     

Temporal and Spatial Compartmentalization of Drug-Resistant Cytomegalovirus (CMV) in a Child with CMV Meningoencephalitis: Implications for Sampling in Molecular Diagnosis

We describe a case of antiviral-resistant cytomegalovirus meningoencephalitis occurring after hematopoietic stem cell transplantation. Antiviral-resistant cytomegalovirus was identified in blood 16 months earlier. However, wild-type cytomegalovirus was evidenced in blood when the meningoencephalitis was diagnosed. Treatment of meningoencephalitis should be adapted to all previously identified resistance mutations in any compartment.     

Peri-implant bone preservation of a novel,self-cutting,and fully tapered implant in the healed crestal ridge of minipigs: submerged vs. transgingival healing

Clinical Oral Investigations - The aim of this study was to assess the influence of transgingival compared with submerged healing on peri-implant bone maintenance around a novel, fully tapered...