Abstract | OBJECTIVES: The aims of this study were 1) to evaluate the role of blood pressure and associated neural tonicity in ambient ischemia of a group of hypertensive patients with stable angina, and 2) to determine the efficacy of immediate release nifedipine therapy in controlling the total ischemic burden in both office-measured and ambulatory blood pressure. BACKGROUND: Low heart rate ischemia, as detected by Holter ambulatory electrocardiographic monitoring, suggests that reduced coronary flow is the major factor leading to ischemia. We previously found that 91% of the ischemic episodes in our hypertensive patients with stable angina were silent. METHODS: We measured plasma norepinephrine content during ischemic events from blood obtained from automatic pump withdrawal with the assistance of a real-time ST segment depression monitor. We then related the norepinephrine content to ischemic episodes assessed by 48-h Holter recording, blood pressure reading by ambulatory blood pressure monitoring and patients' diaries. Measurements were taken during the placebo period and immediate-release nifedipine therapy in 30 hypertensive patients (20 with and 10 without stable angina). RESULTS: More than half of the patients had ischemic episodes; 95% of these were silent. Ischemic episodes peaked in the early morning, and 55% occurred during routine sedentary activities. There was a 10% to 15% increase in heart rate at the onset of ischemia associated with a 30% higher plasma norepinephrine level. Seventy-five percent of patients had increased norepinephrine after nifedipine therapy. Nifedipine therapy controlled measured blood pressure but not 24-h ambulatory blood pressure. Ischemic episodes were reduced only in patients whose ambulatory blood pressure was controlled. CONCLUSIONS: The results suggest that increased neural tone at the time of the ischemic event may play a role in reducing coronary perfusion leading to silent ischemia. Nifedipine therapy (immediate release) was effective in control of ischemia only when both ambulatory and office-measured blood pressure were controlled.
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Authors | D D Lee, K Rigonan, V Dequattro |
Journal | Journal of the American College of Cardiology
(J Am Coll Cardiol)
Vol. 22
Issue 5
Pg. 1438-45
(Nov 01 1993)
ISSN: 0735-1097 [Print] United States |
PMID | 8227803
(Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Nifedipine
- Norepinephrine
- Epinephrine
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Topics |
- Activities of Daily Living
- Adult
- Aged
- Angina Pectoris
(complications, diagnosis, drug therapy, physiopathology)
- Blood Pressure
(drug effects)
- Circadian Rhythm
- Echocardiography
- Electrocardiography, Ambulatory
- Epinephrine
(blood)
- Female
- Heart Rate
- Humans
- Hypertension
(complications, diagnosis, drug therapy, physiopathology)
- Male
- Middle Aged
- Myocardial Ischemia
(complications, diagnosis, drug therapy, physiopathology)
- Nifedipine
(pharmacology, therapeutic use)
- Norepinephrine
(blood)
- Sympathetic Nervous System
(physiopathology)
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