Unusual atrial response to electrical pacing during ischemia

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Tokuhisa Uejima1, Koichi Sagara, Takeshi Yamashita

  • 1Cardiovascular Institute Hospital, Tokyo, Japan. t.uejima@nifty.ne.jp

Journal of Electrocardiology
|January 12, 2002
PubMed

Insights

A patient with unstable angina experienced prolonged atrial intervals during cardiac ischemia, alongside an unusual electrophysiological phenomenon where atrial capture occurred at 90 ppm but not 80 ppm.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Cardiac Surgery

Background:

  • A 76-year-old woman with a dual chamber pacemaker presented with unstable angina requiring coronary intervention.
  • Post-procedure, recurrent chest pain and reduced distal coronary flow necessitated emergent coronary artery bypass grafting.

Observation:

  • During the ischemic events, a prolonged stimulation-excitation interval of the atrium was noted.
  • An unusual electrophysiological phenomenon was observed: atrial capture at 90 beats per minute (bpm) but not at 80 bpm.

Findings:

  • The atrial stimulation-excitation interval prolongation correlated with the severity of myocardial ischemia.
  • The observed capture phenomenon suggests potential phase 4 depolarization or rate-dependent conduction facilitation in the ischemic atrium.

Implications:

  • This case highlights a potential link between myocardial ischemia and altered atrial electrophysiology in pacemaker patients.
  • Understanding such transient electrophysiological changes is crucial for managing cardiac patients, especially those with implanted devices.
  • Further research may elucidate the mechanisms behind rate-dependent conduction abnormalities during acute ischemia.

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