84740
document
Increased blood pressure and neural tone in the silent ischemia of hypertension : disparate effects of immediate release nifedipine . 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 .
84741
Intervention_Pharmacological
nifedipine
84742
Intervention_Pharmacological
nifedipine
84743
Intervention_Pharmacological
real-time ST segment depression monitor
84744
Intervention_Control
placebo
84745
Intervention_Pharmacological
nifedipine therapy
84746
Intervention_Pharmacological
nifedipine
84747
Intervention_Pharmacological
Nifedipine therapy ( immediate release )
84748
Outcome_Physical
blood pressure
84749
Outcome_Physical
neural tone
84750
Outcome_Physical
blood pressure
84751
Outcome_Physical
neural tonicity
84752
Outcome_Other
efficacy
84753
Outcome_Physical
ischemic episodes
84754
Outcome_Physical
Ischemic episodes
84755
Outcome_Physical
heart rate
84756
Outcome_Physical
plasma norepinephrine level
84757
Outcome_Physical
norepinephrine
84758
Outcome_Physical
blood pressure
84759
Outcome_Physical
24-h ambulatory blood pressure
84760
Outcome_Physical
Ischemic episodes
84761
Outcome_Physical
neural tone
84762
Outcome_Physical
control of ischemia
84763
Outcome_Physical
blood pressure
84764
Participant_Condition
hypertensive patients with stable angina
84765
Participant_Sample-size
30
84766
Participant_Sample-size
20 with and 10 without stable angina