Acute and Chronic Stimulation Thresholds of Intramyocardial Screw-in Pacemaker Electrodes

D. S. Starr, G. M. Lawrie, G. C. Morris

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Two screw-in intramyocardial electrodes were inserted in the left ventricle of each of 6 mongrel dogs, and the electrical characteristics were studied over a six-month period. The unipolar lead configuration had consistently better threshold and sensing values than the bipolar configuration during this period. Peaking between implantation and 3 weeks later, mean lead thresholds increased significantly (unipolar, 0.4 to 8.2 μJ; bipolar, 0.6 to 10.2 μJ) while R wave amplitude decreased (unipolar, 16.6 to 8.5 mv; bipolar, 10.6 to 5.8 mv). Mean chronic values for stimulation thresholds were as follows: unipolar, 2.6 μJ, and bipolar, 3.1 μJ. Mean values for the R wave amplitude were as follows: unipolar, 10.6 mv, and bipolar, 7.2 mv. Analysis of the results indicated that with certain exceptions, the optimum system has 2 intramyocardial electrodes, 1 in unipolar configuration and 1 “reserve.” In general, adequate values at implantation are a stimulation threshold of 1.4 μ) (e.g., 1.1 v at 500 ohms and 0.6 msec pulse width) and an R wave amplitude of 5 mv.

Original languageEnglish (US)
Pages (from-to)334-338
Number of pages5
JournalAnnals of Thoracic Surgery
Issue number4
StatePublished - 1981

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine


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