Acute cardiac effects of nicotine in healthy young adults.
Level 2 - randomized trial
Individual double-blind randomized crossover trial
PubMed 12356338 · doi:10.1046/j.1540-8175.2002.00443.x
What was done
A double-blind, randomized crossover trial evaluated the acute hemodynamic and electrophysiological effects of 4 mg nicotine gum versus placebo in 11 healthy nonsmoking adults (6 males, 5 females; ages 23–36 years). Echocardiography and signal-averaged electrocardiography (SAECG) were conducted 20 minutes post-chewing (at peak nicotine levels). After 40 minutes, subjects received the alternate intervention in crossover fashion. Measured variables included end-systolic wall stress (ESWS), systemic vascular resistance (SVR), cardiac output, stroke volume, shortening fraction, heart-rate-corrected velocity of circumferential fiber shortening (Vcfc), and SAECG P wave and QRS durations.
What was found
Statistically significant differences (P < 0.05) compared to control or placebo were observed for ESWS, mean blood pressure, cardiac output, SVR, heart rate, and P wave duration. No significant differences were detected for left ventricular ejection time, left ventricular dimensions, shortening fraction, myocardial contractility (Vcfc), or QRS duration. The abstract reports no exact numerical values, effect sizes, or confidence intervals.
Why it matters
This study demonstrates that acute nicotine exposure primarily elevates cardiac afterload, blood pressure, and heart rate while prolonging atrial conduction time, without directly altering intrinsic myocardial contractility in healthy individuals.
Limits
The study is limited by a very small sample size (n = 11) and only tested young, healthy nonsmoking adults after a single acute dose. Long-term effects, dose-dependent variations, and responses in habitual tobacco users or individuals with cardiovascular disease were not evaluated. Absolute numeric data are omitted from the abstract.