10629
document
Acute cardiac effects of nicotine in healthy young adults . BACKGROUND Nicotine is known to have many physiologic effects . The influence of nicotine delivered in chewing gum upon cardiac hemodynamics and conduction has not been well-characterized . METHODS We studied the effects of nicotine in nonsmoking adults ( 6 male , 5 female ; ages 23-36 years ) using a double-blind , randomized , cross-over study . Subjects chewed nicotine gum ( 4 mg ) or placebo . After 20 minutes ( approximate time to peak nicotine levels ) , echocardiograms and signal-averaged electrocardiograms ( SAECG ) were obtained . After 40 minutes , subjects were again given nicotine gum or placebo in cross-over fashion . Standard echocardiographic measurements were made from two-dimensional images . We then calculated end-systolic wall stress ( ESWS ) , shortening fraction ( SF ) , systemic vascular resistance ( SVR ) , velocity for circumferential fiber shortening corrected for heart rate ( Vcfc ) , stroke volume , and cardiac output . P wave and QRS duration were measured from SAECG . RESULTS Significant differences ( P < 0.05 ) from control or placebo were found for ESWS , mean blood pressure , cardiac output , SVR , heart rate , and P wave duration . No significant changes were seen in left ventricular ejection time ( LVET ) , LV dimensions , SF , contractility ( Vcfc ) , or QRS duration . CONCLUSIONS These results suggest that nicotine chewing gum increases afterload and cardiac output . Cardiac contractility does not change acutely in response to nicotine gum . Heart rate and P wave duration are increased by chewing nicotine gum .
10630
Intervention_Pharmacological
nicotine
10631
Intervention_Pharmacological
nicotine
10632
Intervention_Pharmacological
nicotine
10633
Intervention_Pharmacological
nicotine gum ( 4 mg )
10634
Intervention_Control
placebo
10635
Intervention_Physical
echocardiograms and signal-averaged electrocardiograms
10636
Intervention_Pharmacological
nicotine gum
10637
Intervention_Control
placebo
10638
Outcome_Physical
end-systolic wall stress ( ESWS ) , shortening fraction ( SF ) , systemic vascular resistance ( SVR ) , velocity for circumferential fiber shortening corrected for heart rate ( Vcfc ) , stroke volume , and cardiac output . P wave and QRS duration
10639
Outcome_Other
ESWS
10640
Outcome_Physical
blood pressure
10641
Outcome_Other
cardiac output
10642
Outcome_Other
SVR
10643
Outcome_Other
heart rate
10644
Outcome_Other
P wave duration
10645
Outcome_Physical
left ventricular ejection time ( LVET ) , LV dimensions
10646
Outcome_Physical
SF
10647
Outcome_Physical
contractility ( Vcfc )
10648
Outcome_Physical
QRS duration
10649
Outcome_Physical
afterload and cardiac output . Cardiac contractility
10650
Outcome_Physical
Heart rate
10651
Outcome_Physical
P wave duration