{
  "abstract": "Background: Upper septal fascicular ventricular tachycardia (VT) is a rare form of idiopathic left ventricular tachycardia arising from the proximal His-Purkinje system. Because near-synchronous ventricular activation can produce a relatively narrow QRS complex, this arrhythmia may closely mimic supraventricular tachycardia (SVT) with aberrant conduction.\n\nCase presentation: A 25-year-old man without structural heart disease presented with recurrent palpitations for more than 4 years. ECG during tachycardia showed a regular narrow-complex tachycardia at approximately 200 beats/min with atypical right bundle-branch block-like morphology and marked right-axis deviation. Electrophysiological study initially raised suspicion for an AVNRT-like mechanism because programmed atrial stimulation demonstrated dual AV nodal physiology and intracardiac recordings showed an apparent near-simultaneous ventriculoatrial relationship. However, 6 mg intravenous adenosine did not terminate the tachycardia but unmasked atrioventricular dissociation, with the ventricular rate exceeding the atrial rate; together with subsequent Purkinje-system mapping, this supported a ventricular origin. Initial mapping identified an effective target in the distal left posterior fascicular region, where 30-W radiofrequency ablation terminated the tachycardia. The same night, incessant tachycardia recurred with a changed and narrower QRS morphology. Repeat mapping localized the final successful target to the upper septal region approximately 8 mm from the His bundle; 20-W radiofrequency ablation terminated the tachycardia without atrioventricular conduction injury. No symptomatic recurrence was reported during 12-month clinical follow-up.\n\nConclusion: A relatively narrow or progressively narrowing QRS complex does not exclude VT. In suspected SVT with atypical features, adenosine-unmasked atrioventricular dissociation should prompt reconsideration of a ventricular mechanism, while invasive electrophysiological assessment and repeat mapping may facilitate accurate diagnosis and safe ablation, particularly when the arrhythmogenic substrate is adjacent to the His bundle.",
  "abstract_shown": true,
  "affiliations": [
    "School of Medicine, University of Electronic Science and Technology of China",
    "Department of Cardiology, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Yilin Fu"
    },
    {
      "affs": [
        0
      ],
      "name": "Jia Tang"
    },
    {
      "affs": [
        0
      ],
      "name": "Zixiang Zhao"
    },
    {
      "affs": [
        0
      ],
      "name": "Yongxiang Cai"
    },
    {
      "affs": [
        1
      ],
      "name": "Yang Chen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/echw3t67nw68b.bib",
  "cited_by": 0,
  "doi": "10.3389/fcvm.2026.1933819",
  "fulltext_url": null,
  "id": "echw3t67nw68b",
  "issns": [
    "2297-055X"
  ],
  "landing_url": "https://www.frontiersin.org/articles/10.3389/fcvm.2026.1933819/full",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-29",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/echw3t67nw68b.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:10Z",
      "native_id": "10.3389/fcvm.2026.1933819",
      "source": "crossref",
      "url": "https://www.frontiersin.org/articles/10.3389/fcvm.2026.1933819/full"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "issn:2297-055X",
      "subfield": "cardiovascular"
    }
  ],
  "title": "Case Report: Upper septal fascicular ventricular tachycardia mimicking supraventricular tachycardia: diagnostic pitfalls and mapping-guided ablation",
  "title_text": "Case Report: Upper septal fascicular ventricular tachycardia mimicking supraventricular tachycardia: diagnostic pitfalls and mapping-guided ablation",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T00:21:07Z",
  "url": "https://research.draconitic.com/paper/echw3t67nw68b",
  "venue": "Frontiers in Cardiovascular Medicine",
  "versions": []
}