Acetylsalicylic acid and autonomic modulation

Cardiovascular Events After Partner Bereavement, What is the Role of Low Dose Aspirin and Beta-Blockers?

Bereavement due to loss of a partner is one of the most stressful life events, often leading to adverse physiological responses. Spousal loss has been associated with an increased morbidity and mortality, particularly from cardiovascular disease. Use of aspirin and/or beta adrenergic blockers have previously been suggested to play a role in cardiovascular risk associated with early bereavement. However, the available literature regarding this topic is limited. In this review article, we explore the potential beneficial role of aspirin and beta blockers in early bereavement. Our systematic review suggests that most studies have found aspirin and beta blockers to be beneficial in preventing adverse cardiovascular outcomes associated with early bereavement. Further randomized controlled long-term studies are warranted with adequate sample size to clearly establish the role of these medications on cardiovascular disease in late bereavement.

Autonomic imbalance in cardiac surgery: A potential determinant of the failure in remote ischemic preconditioning

Remote ischemic preconditioning (RIPC) is a cardioprotective strategy against myocardial damage by ischemia-reperfusion. Many in-vivo and ex-vivo animal researches have demonstrated that RIPC decreases significantly the ischemia-reperfusion myocardial damage, by up to 58% in isolated rat heart. Cardiac artery bypass graft surgery (CABG) is a clinical model of myocardial ischemia-reperfusion and a clinical potential application to RIPC. However, although RIPC has shown successful results in experimental studies, clinical trials on CABG have failed to demonstrate a benefit of RIPC in humans. Strikingly, the main proposed factors associated with this translational failure also impair the balance of the autonomic nervous system (ANS), which has shown to play a key role in RIPC cardioprotection in animal models. Comorbidities, chronic pharmacological treatment and anesthesic drugs - common conditions in CABG patients - cause an ANS imbalance through parasympathetic activity decrement. On the other hand, ANS and specially the parasympathetic branch are essentials to get cardioprotection by RIPC in animal models. Consequently, we propose that ANS imbalance in CABG patients would explain the failure of RIPC clinical trials. Whether our hypothesis is true, many patients could be benefited by RIPC: a cheap, simple and virtually broad-available cardioprotective maneuver. In this paper we discuss the evidence that support this hypothesis and its clinical implications.

Low-dose Aspirin Inhibits Cardiac Sympathetic Activation and Vagal Withdrawal Response to Morning Rising

Aspirin is known to interfere with platelet function and can protect individuals at risk of sudden death. However, this property of aspirin is less defined for cardiac autonomic activity. We assessed pulse rate variability by spectral analysis and measured plasma eicosanoid levels before and after administration of 81-mg aspirin to 12 healthy subjects over a 60-degree head-up tilt test in the morning. In upright posture, low-dose aspirin decreased both the normalized unit value of low-frequency (normalized LF) power (mean ± SD, 82.5 ± 4.5 vs. 77.5 ± 6.5 nu, P = 0.01) and LF/HF ratio (6.0 ± 2.1 vs. 4.7 ± 2.7, P = 0.02) and augmented the normalized unit value of high-frequency power (15.0 ± 4.4 vs. 19.8 ± 6.4 nu, P = 0.004). It simultaneously upregulated plasma 6-keto-PGF1α level (13.4 ± 6.8 vs. 19.7 ± 12.8 pg/mL, P = 0.04) and inhibited plasma thromboxane B2 (TXB2) level (11.6 ± 7.3 vs. 6.3 ± 4.2 pg/mL, P = 0.003). In the upright posture, both before and after aspirin, there was a significant direct correlation between plasma TXB2 levels and the normalized LF power (r = 0.42, P = 0.04) as well as between the plasma TXB2/6-keto-PGF1α ratio and the normalized LF power (r = 0.50, P = 0.01). Administration of low-dose aspirin in healthy people inhibits cardiac sympathetic activation and vagal withdrawal response to morning rising through an alternation of the TXA2/PGI2 balance.

The effects of acetylic salicylic acid on heart rate variability in healthy subjects

In this placebo controlled double blind cross over study multiple daily dosing with 500 mg acetylic salicylic acid did not influence heart rate variability in 16 healthy male volunteers aged 25 (22-28) years (median; range) to a relevant extent (p > 0.05).

Standardized tests of heart rate variability: normal ranges obtained from 309 healthy humans, and effects of age, gender, and heart rate

The authors undertook this study to determine the effects of age, gender, and heart rate (HR) on the results of cardiac autonomic function tests for measuring heart rate variability (HRV) in a large sample of healthy subjects (n = 309). Conventional tests (deep breathing, maximum/minimum 30:15 ratio), and a standardized 5-minute resting study, including spectral analysis of HR, were used. The main findings included (1) the indices of all tests, except for the ratio of the low- (LF) to high-frequency (HF) spectral power (LF/HF ratio) and HR itself, are inversely related to age in both sexes; (2) the 5-minute spectral bands (except for the LF/HF ratio), the variation coefficient, expiratory-inspiratory ratio during deep breathing, and the maximum/minimum 30:15 ratio are independent of HR; (3) women up to the age of 55 years have a higher resting HR compared with men; (4) young and middle-aged women show a significantly lower LF power and LF/HF ratio compared with age-matched men, whereas no significant gender differences are observed in the absolute HF power. The authors computed age- and gender-dependent normal values for each of the HRV indices studied here and discuss the clinical consequences arising from gender differences in HRV.