Atrioventricular (AV) accessory pathways (APs) provide additional electrical connections between the atria and ventricles, resulting in severe electrical disturbances. It is generally accepted that APs originate in the altered annulus fibrosus maturation in the late prenatal and perinatal period. However, current experimental methods cannot address their development in specific locations around the annulus fibrosus because of the inaccessibility of late fetal hearts for electrophysiological investigation under physiological conditions. In this study, we describe an approach for optical mapping of the retrogradely perfused chick heart in the last third of the incubation period. This system showed stability for electrophysiological measurement for several hours. This feature allowed analysis of the number and functionality of the APs separately in each clinically relevant position. Under physiological conditions, we also recorded the shortening of the AV delay with annulus fibrosus maturation and analyzed ventricular activation patterns after conduction through APs at specific locations. We observed a gradual regression of AP with an area-specific rate (left-sided APs disappeared first). The results also revealed a sudden drop in the number of active APs between embryonic days 16 and 18. Accessory myocardial AV connections were histologically documented in all positions around the annulus fibrosus even after hatching. The fact that no electrically active AP was present at this stage highlights the necessity of electrophysiological evaluation of accessory atrioventricular connections in studying AP formation.NEW & NOTEWORTHY We present the use of retrograde perfusion and optical mapping to investigate, for the first time, the regression of accessory pathways during annulus fibrosus maturation, separately examining each clinically relevant location. The system enables measurements under physiological conditions and demonstrates long-lasting stability compared with other approaches. This study offers applications of the model to investigate electrical and/or functional development in late embryonic development without concern about heart viability.

• MeSH
• akční potenciály * MeSH
• kuřecí embryo MeSH
• nodus atrioventricularis embryologie   patofyziologie   MeSH
• perfuze MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: During electrophysiological mapping of tachycardias, putative target sites are often only truly confirmed to be vital after observing the effect of ablation. This lack of mapping specificity potentiates inadvertent ablation of innocent cardiac tissue not relevant to the arrhythmia. But if myocardial excitability could be transiently suppressed at critical regions, their suitability as targets could be conclusively determined before delivering tissue-destructive ablation lesions. We studied whether reversible pulsed electric fields (PFREV) could transiently suppress electrical conduction, thereby providing a means to dissect tachycardia circuits in vivo. METHODS: PFREV energy was delivered from a 9-mm lattice-tip catheter to the atria of 12 swine and 9 patients, followed by serial electrogram assessments. The effects on electrical conduction were explored in 5 additional animals by applying PFREV to the atrioventricular node: 17 low-dose (PFREV-LOW) and 10 high-dose (PFREV-HIGH) applications. Finally, in 3 patients manifesting spontaneous tachycardias, PFREV was applied at putative critical sites. RESULTS: In animals, the immediate post-PFREV electrogram amplitudes diminished by 74%, followed by 78% recovery by 5 minutes. Similarly, in patients, a 69.9% amplitude reduction was followed by 84% recovery by 3 minutes. Histology revealed only minimal to no focal, superficial fibrosis. PFREV-LOW at the atrioventricular node resulted in transient PR prolongation and transient AV block in 59% and 6%, while PFREV-HIGH caused transient PR prolongation and transient AV block in 30% and 50%, respectively. The 3 tachycardia patients had atypical atrial flutters (n=2) and atrioventricular nodal reentrant tachycardia. PFREV at putative critical sites reproducibly terminated the tachycardias; ablation rendered the tachycardias noninducible and without recurrence during 1-year follow-up. CONCLUSIONS: Reversible electroporation pulses can be applied to myocardial tissue to transiently block electrical conduction. This technique of pulsed field mapping may represent a novel electrophysiological tool to help identify the critical isthmus of tachycardia circuits.

• MeSH
• atrioventrikulární blokáda * MeSH
• atrioventrikulární nodální reentry tachykardie * MeSH
• elektrofyziologické techniky kardiologické MeSH
• elektrokardiografie MeSH
• katetrizační ablace * škodlivé účinky   metody   MeSH
• lidé MeSH
• nodus atrioventricularis MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

AIMS: Interventional cardiology procedures may expose patients and staff to considerable radiation doses. We aimed to assess whether exposure to ionizing radiation during catheter ablation of supraventricular tachycardia (SVT) can be completely avoided. METHODS AND RESULTS: In this prospective randomized study, patients with SVT (atrioventricular re-entrant tachycardia n = 94, typical atrial flutter n = 29) were randomly assigned in a 1:1 ratio to catheter ablation with conventional fluoroscopic guidance (CF group) or with the EnSite Precision mapping system [zerofluoro (ZF) group]. Acute procedural parameters, increased stochastic risk of cancer incidence and 6-month follow-up data were assessed. Between May 2019 and August 2020, 123 patients were enrolled. Clinical parameters were comparable. Median procedural time was 60.0 and 58.0 min, median fluoroscopy time and estimated median effective dose were 240 s vs. 0 and 0.38 mSv vs. 0 and arrhythmia recurrence was 5% and 7.9% in the CF and ZF groups, respectively. The acute success rate was 98.4% in both groups. No procedure-related complications were reported. At an average age of 55.5 years and median radiation exposure of 0.38 mSv, the estimate of increased incidence was approximately 1 in 14 084. The estimated mortality rate was 1 per 17 857 exposed persons. CONCLUSIONS: The procedural safety and efficacy of the zero-fluoroscopic approach are similar to those of conventional fluoroscopy-based ablation for atrioventricular nodal re-entrant tachycardia and atrial flutter. Under the assumption of low radiation dose, the excessive lifetime risk of malignancy in the CF group due to electrophysiology procedure is reasonably small, whilst totally reduced in zero fluoroscopy procedures.

• MeSH
• atrioventrikulární nodální reentry tachykardie * diagnostické zobrazování   chirurgie   MeSH
• fluoroskopie metody   MeSH
• flutter síní * diagnostické zobrazování   chirurgie   MeSH
• katetrizační ablace * škodlivé účinky   metody   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nodus atrioventricularis MeSH
• prospektivní studie MeSH
• srdeční arytmie chirurgie   MeSH
• supraventrikulární tachykardie * diagnostické zobrazování   chirurgie   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH

• MeSH
• akční potenciály MeSH
• atrioventrikulární nodální reentry tachykardie diagnóza   patofyziologie   chirurgie   MeSH
• dospělí MeSH
• elektrofyziologické techniky kardiologické MeSH
• katetrizační ablace metody   MeSH
• lidé MeSH
• nodus atrioventricularis inervace   MeSH
• nodus sinuatrialis inervace   MeSH
• srdeční frekvence MeSH
• výsledek terapie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

• MeSH
• amiodaron terapeutické užití   MeSH
• antiarytmika * terapeutické užití   MeSH
• beta blokátory * terapeutické užití   MeSH
• digoxin terapeutické užití   MeSH
• fibrilace síní * komplikace   terapie   MeSH
• katetrizační ablace * metody   MeSH
• lidé MeSH
• nodus atrioventricularis * chirurgie   MeSH
• srdeční resynchronizační terapie * metody   MeSH
• srdeční selhání * komplikace   terapie   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

• MeSH
• fibrilace komor etiologie   terapie   MeSH
• fibrilace síní chirurgie   terapie   MeSH
• katetrizační ablace škodlivé účinky   MeSH
• lidé MeSH
• nodus atrioventricularis chirurgie   MeSH
• senioři MeSH
• srdeční resynchronizační terapie MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

AIMS: In patients with severe neurally mediated syncope (NMS), radiofrequency catheter ablation (RFA) of ganglionic plexi (GP) has been proposed as a new therapeutic approach. Cardio-inhibitory response during NMS is usually related to the sinoatrial (SA) and less frequently to atrioventricular (AV) node. Differential effect of GP ablation on SA and AV node is poorly understood. METHODS AND RESULTS: We report a case of a 35-year-old female with frequent symptomatic episodes of advanced AV block treated by anatomically guided RFA at empirical sites of GPs. After RFA at the septal portion of the right atrium-superior vena cava junction, heart rate accelerated from 62 to 91 beats/min and PR interval prolonged from 213 to 344 ms. Sustained first-degree AV block allowed to observe directly the effects of subsequent RFA on the AV nodal properties. Subsequent RFA at right- and left-sided aspects of the inter-atrial septum had no further effect on heart rate and PR interval. Ablation at the inferior left GP was critical for restoration of normal AV conduction (final PR interval of 187 ms). No bradycardia episodes were observed by implantable loop recorder during the follow-up of 10 months and the patient was symptomatically improved. CONCLUSION: This is the first clinical case showing the differential effect of GP ablation on SA and AV nodal function, and critical importance of targeting the GP at the postero-inferior left atrium. The successful procedure corroborates clinical utility of ablation treatment instead of pacemaker implantation in selected patients with cardio-inhibitory NMS.

• MeSH
• akční potenciály MeSH
• atrioventrikulární blokáda diagnóza   patofyziologie   chirurgie   MeSH
• autonomní denervace metody   MeSH
• časové faktory MeSH
• dospělí MeSH
• elektrofyziologické techniky kardiologické MeSH
• elektrokardiografie MeSH
• ganglia autonomní patofyziologie   chirurgie   MeSH
• katetrizační ablace * MeSH
• lidé MeSH
• nodus atrioventricularis patofyziologie   MeSH
• nodus sinuatrialis patofyziologie   MeSH
• recidiva MeSH
• srdeční frekvence MeSH
• stupeň závažnosti nemoci MeSH
• vazovagální synkopa diagnóza   patofyziologie   chirurgie   MeSH
• výsledek terapie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

Převodní systém srdeční byl ve formě přítomné u teplokrevných obratlovců úplně popsán před 110 lety. Navzdory tomu bylo v poslední době získáno množství poznatků o jeho specifikaci a vývoji, jež mají význam pro jeho funkci při tvorbě a vedení vzruchu srdcem. Poruchy převodního systému jsou spojovány s arytmiemi, z nichž některé mají vývojový podklad. Evoluční pohled na tuto problematiku je užitečný zejména pro lepší pochopení přestavby síňokomorového kanálu.

Cardiac conduction system was described in its complete form in homeotherm vertebrates 110 years ago. Despite this fact, many new findings concerning its specification and development that have an impact on its pacemaking and conducting function appeared in the past decade. Conduction system disorders are associated with arrhythmias, and some of which have a developmental origin. Evolutionary view on this area is particularly useful for better understanding of the atrioventricular canal remodelling.

• MeSH
• blokáda Tawarova raménka MeSH
• Hisův svazek fyziologie   MeSH
• nodus atrioventricularis fyziologie   MeSH
• nodus sinuatrialis fyziologie   MeSH
• převodní systém srdeční * fyziologie   patofyziologie   MeSH
• Purkyňova vlákna fyziologie   MeSH
• srdeční arytmie patofyziologie   patologie   MeSH

This study evaluated hemodynamic feasibility and reproducibility of a new method for in vivo simulation of human atrial fibrillation (AF). The method was tested during sinus rhythm in 10 patients undergoing catheter ablation for AF. A simple electronic device was assembled that allowed triggering a cardiac stimulator by predefined series of RR intervals. Irregular RR interval sequences with a mean heart rate of 90/min and 130/min were obtained from ECG recordings of another patients with AF. Simultaneous atrioventricular pacing was delivered by catheters placed inside the coronary sinus and at the His bundle region. Hemodynamic effect of the simulated AF was assessed by invasive measurement of the left ventricular (LV) pressure, dP/dt, and Tau. Compared to regular pacing at the same mean heart rate, the simulated AF significantly impaired the LV both systolic and diastolic function. Repeated AF pacing in the same patients generated similar LV hemodynamics. The proposed method provides a realistic and reproducible in-vivo model of AF. It can be exploited for investigation of the hemodynamic consequences of AF in various patient populations.

• MeSH
• elektrokardiografie MeSH
• fibrilace síní patofyziologie   chirurgie   MeSH
• hemodynamika * MeSH
• kardiostimulace umělá MeSH
• katetrizační ablace MeSH
• lidé středního věku MeSH
• lidé MeSH
• nodus atrioventricularis patofyziologie   MeSH
• senioři MeSH
• srdce diagnostické zobrazování   MeSH
• srdeční frekvence MeSH
• srdeční komory patofyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The sphingosine-1-phosphate (S1P) receptor modulator, fingolimod (FTY720), has been used for the treatment of patients with relapsing forms of multiple sclerosis, but atrioventricular (AV) conduction block have been reported in some patients after the first dose. The underlying mechanism of this AV node conduction blockade is still not well-understood. In this study, we hypothesize that expression of this particular arrhythmia might be related to a direct effect of FTY720 on AV node rather than a parasympathetic mimetic action. We, therefore, investigated the effect of FTY720 on AV nodal, using in vitro rat model preparation, under both basal as well as ischaemia/reperfusion conditions. We first look at the expression pattern of S1P receptors on the AV node using real-time PCR. Although all three S1P receptor isoforms were expressed in AVN tissues, S1P1 receptor isoform expression level was higher than S1P2 and S1P3. The effect of 25 nM FTY720 on cycle length (CL) was subsequently studied via extracellular potentials recordings. FTY720 caused a mild to moderate prolongation in CL by an average 9% in AVN (n = 10, P < 0.05) preparations. We also show that FTY720 attenuated both ischaemia and reperfusion induced AVN rhythmic disturbance. To our knowledge, these remarkable findings have not been previously reported in the literature, and stress the importance for extensive monitoring period in certain cases, especially in patients taking concurrently AV node blocker agents.

• MeSH
• disekce MeSH
• fingolimod hydrochlorid farmakologie   MeSH
• krysa rodu rattus MeSH
• lysofosfolipidy farmakologie   MeSH
• messenger RNA genetika   metabolismus   MeSH
• nodus atrioventricularis účinky léků   patofyziologie   MeSH
• receptory lysosfingolipidů metabolismus   MeSH
• regulace genové exprese účinky léků   MeSH
• reperfuzní poškození patologie   patofyziologie   MeSH
• sfingosin analogy a deriváty   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH