D D Lee1, K Rigonan, V Dequattro. 1. Clinical Hypertension Service, University of Southern California School of Medicine, Los Angeles 90033.
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.
RCT Entities:
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 hypertensivepatients 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 hypertensivepatients 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 hypertensivepatients (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.
Authors: Simon Le Floc'h; Jacques Ohayon; Philippe Tracqui; Gérard Finet; Ahmed M Gharib; Roch L Maurice; Guy Cloutier; Roderic I Pettigrew Journal: IEEE Trans Med Imaging Date: 2009-01-19 Impact factor: 10.048