Author + information
- Received August 27, 1992
- Revision received July 8, 1993
- Accepted July 22, 1993
- Published online December 1, 1993.
- Guido Pomidossi, MDa,
- Antonio Saino, MDa,
- Rodolfo Perondi, MDa,
- Luisa Gregorini, MDa,
- Patrizia Alessio, MDb,
- Alberto Rimini, MDa,
- Stefano Omboni, MDa,
- Alberto Zanchetti, MDa and
- Giuseppe Mancia, MD∗,a
- ↵∗Address for correspondence: Dr. Giuseppe Mancia, Centro Fisiologia Clinica e Ipertensione, Via F. Sforza 35, 20122 Milan, Italy.
Objectives. The aim of this study was to assess whether transient episodes of symptomatic or silent myocardial ischemia affect baroreceptor modulation of heart rate.
Background. Animal and human studies have shown that myocardial infarction is accompanied by an impairment of the baroreceptor influences on the sinus node. However, whether this also occurs during transient myocardial ischemia has never been documented.
Methods. In 12 patients undergoing coronary angiography, systolic blood pressure (intraarterial catheter) was reduced by an intravenous bolus of nitroglycerin during a spontaneous episode of transient chest pain and myocardial ischemia (ST segment depression on the electrocardiogram) and 30 min after recovery. The slope of the linear regression between the decrease in systolic blood pressure and the RR interval shortening was taken as the measure of baroreflex sensitivity.
Results. During ischemia, baroreflex sensitivity was 1.3 ± 0.3 ms/mm Hg (mean ± SEM), whereas recovery it was markedly and significantly greater (2.6 ± 0.5 Hg, p < 0.01). Similar results were obtained in eight other patients who experienced a silent ischemic episode either spontaneously or during coronary angioplasty. The reduction in baroreflex sensitivity was similarly pronounced during inferior (10 patients) and anterior (10 patients) ischemia, and its magnitude showed little or no relation to the ischemia-dependent changes in blood pressure and heart rate.
Conclusions. Transient myocardial ischemia is associated with marked baroreflex impairment The impairment occurs even during symptomless ischemic episodes and is therefore not related to pain or to other nonspecific influences on the baroreflex.
- Received August 27, 1992.
- Revision received July 8, 1993.
- Accepted July 22, 1993.