Background
- Superior-type fast-slow (sup-F/S-) atrioventricular nodal reentrant tachycardia (AVNRT) is a rare AVNRT variant using a superior (sup-) slow pathway (SP) as the retrograde limb. Its intracardiac appearance, characterized by a short atrio-His (AH) interval and the earliest site of atrial activation in the His-bundle (HB; EAA-HB), is an initial indicator for making a diagnosis.
Methods
- Among 22 consecutive patients with sup-F/S-AVNRT, three (age, 68-81 years) patients had an apparent but not typical slow-fast (S/F) AVNRT characterized by a long AH interval and EAA-HB (tachy-long-AH).
Results
- The diagnosis of sup-F/S-AVNRT was based on the standard criteria in two patients and on the occurrence of Wenckebach-type AV block during tachycardia, which was attributable to a block at the lower common pathway (LCP) below the circuit of the AVNRT, detected owing to the LCP potentials, in one patient. As with the typical S/F-AVNRT, tachy-long-AH was induced after a jump in the AH interval. In contrast to typical S/F-AVNRT, fluctuation in the ventriculoatrial interval was observed during the tachy-long-AH. Ventricular overdrive pacing was unable to entrain or terminate the tachy-long-AH. Moreover, the tachy-long-AH reciprocally transited to/from sup-F/S-AVNRT spontaneously or was triggered by ventricular contractions while the atrial cycle length and EAA remained unchanged. Both tachycardias were cured by ablation at a single site in the right-side parahisian region of two patients and the non-coronary aortic cusp of one patient. Collectively, the essential circuit of both tachycardias was identical, and the tachy-long-AH was diagnosed as another phenotype of sup-F/S-AVNRT accompanied by sustained antegrade conduction via another bystander SP breaking through the HB owing to the repetitive antegrade block at the LCP, thus representing a long AH interval during the ongoing sup-F/S-AVNRT.
Conclusions
- An unknown sup-F/S-AVNRT phenotype exists that apparently mimics the typical S/F-AVNRT and is also an unknown subtype of apparent S/F-AVNRT.
While a KCND3 V392I mutation uniquely displays a mixed electrophysiological phenotype of Kv4.3, only limited clinical information on the mutation carriers is available. We report two teenage siblings exhibiting both cardiac (early repolarization syndrome and paroxysmal atrial fibrillation) and cerebral phenotypes (epilepsy and intellectual disability), in whom we identified the KCND3 V392I mutation. We propose a link between the KCND3 mutation with a mixed electrophysiological phenotype and cardiocerebral phenotypes, which may be defined as a novel cardiocerebral channelopathy.
BackgroundThe epinephrine infusion test (EIT) typically induces marked QT prolongation in LQT1, but not LQT3, while the efficacy of β‐blocker therapy is established in LQT1, but not LQT3. We encountered an LQT3 family, with an SCN5A V1667I mutation, that exhibited epinephrine‐induced marked QT prolongation.MethodsWild‐type (WT) or V1667I‐SCN5A was transiently expressed into tsA‐201 cells, and whole‐cell sodium currents (INa) were recorded using patch‐clamp techniques. To mimic the effects of epinephrine, INa was recorded after the application of protein kinase A (PKA) activator, 8‐CPT‐cAMP (200 μM), for 10 minutes.ResultsThe peak density of V1667I‐INa was significantly larger than WT‐INa (WT: 469 ± 48 pA/pF, n = 20; V1667I: 690 ± 62 pA/pF, n = 19, P < .01). The steady‐state activation (SSA) and fast inactivation rate of V1667I‐INa were comparable to WT‐INa. V1667I‐INa displayed a significant depolarizing shift in steady‐state inactivation (SSI) in comparison to WT‐INa (V1/2‐WT: −88.1 ± 0.8 mV, n = 17; V1667I: −82.5 ± 1.1 mV, n = 17, P < .01), which increases window currents. Tetrodotoxin (30 μM)‐sensitive persistent V1667I‐INa was comparable to WT‐INa. However, the ramp pulse protocol (RPP) displayed an increased hump in V1667I‐INa in comparison to WT‐INa. Although 8‐CPT‐cAMP shifted SSA to hyperpolarizing potentials in WT‐INa and V1667I‐INa to the same extent, it shifted SSI to hyperpolarizing potentials much less in V1667I‐INa than in WT‐INa (V1/2‐WT: −92.7 ± 1.3 mV, n = 6; V1667I: −85.3 ± 1.6 mV, n = 6, P < .01). Concordantly, the RPP displayed an increased hump in V1667I‐INa, but not in WT‐INa.ConclusionsWe demonstrated an increase of V1667I‐INa by PKA activation, which may provide a rationale for the efficacy of β‐blocker therapy in some cases of LQT3.
Introduction: We tested our hypothesis that atrial entrainment pacing (EP) of a) the common-type (com-) fast-slow (F/S-) atypical atrioventricular nodal reentrant tachycardia (AVNRT) using a typical slow pathway (SP), or b) the superior-type (sup-) F/S-AVNRT using a superior SP, both modify the retrograde conduction time across the SP immediately after termination of EP (retro-SP-time).
Methods:We measured the difference in the His-atrial interval (HA difference) immediately after cessation of EP, performed at 2 ± 2 rates from the high right atrium (HA[1]-HRA) versus from the proximal coronary sinus (HA[1]-CS) in 17 patients with com-F/S-AVNRT and 11 patients with sup-F/S-AVNRT. We also measured the atrial-His and HA intervals of the first and second cycles immediately after cessation of EP and during stable tachycardia.Results: Unequal responses, defined as a ≥ 20-ms HA difference at ≥1 EP rates, were observed in 16 patients (57%), including 7 with com-and 9 with sup-F/S-AVNRT.Irrespective of the EP rate, all unequal responses of com-F/S-AVNRT were due to a shorter HA[1]-CS than HA[1]-HRA, with a mean 34 ± 11 ms HA difference, whereas all unequal responses of sup-F/S-AVNRT were due to a longer HA[1]-CS than HA[1]-HRA, with a mean 49 ± 25 ms HA difference. The unequal responses resolved within two cycles after the cessation of EP.
Conclusions:We have identified a little-known pacing site-and pacing ratedependent shortening of the retro-SP-time.
Durch Behandlung von 2′‐Brom‐reticulin (I) mit überschüssigem Trifluoressigsäureanhydrid bei 160°C wird in 7 l%iger Ausbeute das Stilben (II) erhalten, das sich in quantitativer Ausbeute mit Wasserstoff an PtO2 ′zum Dihydrostilben (III) hydrieren läßt. Bestrahlung der Verbindung (III) mit UV‐Licht in Gegenwart von Natronlauge und Natriumjodid führt zum Secomorphinandienon (IV), das sich durch Hydrolyse und intramolekulare Michael‐Addition in das Enon (V) umwandeln läßt (2% Ausbeute).
1. The metabolic fate of a new antitumour agent, 1-hexylcarbamoyl-5-fluoro [6-14C]uracil (14C-HCFU) in rats after oral administration was compared with that of 5-fluoro[6-14C]uracil (14C-FU). 2. Tissue radioactivity reached a max. 1 to 3 h after administration of 14C-HCFU and 0.5 h after 14C-FU. 3. Both drugs were excreted rapidly, mostly in urine. Expired 14CO2 from 14C-HCFU was significantly less than that from 14C-FU. 4. Unchanged FU was not detected in plasma 3 h after administration of 14C-FU, whereas FU was detected in plasma 5 h after 14C-HCFU. The pyrimidine ring of 14C-HCFU might be degradated more slowly than that of 14C-FU. 5. 1-(5-Carboxypentylcarbamoyl)-5-fluorouracil and 1-(3-carboxypropylcarbamoyl)-5-fluorouracil were identified as the major urinary metabolites of 14C-HCFU.
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