Influence of moderately elevated levels of carboxyhemoglobin on the course of acute ischemic heart disease

Nicotine Ingestion Reduces Heart Rate Variability in Young Healthy Adults

Around the whole world, smoking is considered harmful to human health, such as increasing the risk of cardiovascular disease (CVD, such as coronary heart disease and stroke) and lung cancer. The purpose of this study was to explore whether nicotine, the main component of tobacco, has adverse effects on heart rate variability (HRV) in adolescents, so as to remind adolescents not to smoke and not to take pleasure in abusing nicotine. In this study, 40 male and 40 female young healthy nonsmoking subjects were selected to analyze the changes of HRV after taking 4 mg nicotine orally. We found that nicotine reduced HRV in young healthy male and female subjects, and there was no gender difference in this effect (P > 0.05). In conclusion, smoking is harmful to the cardiac system of young people, especially when nicotine content ≥4 mg dosage.

Do carboxyhaemoglobin and methaemoglobin levels predict the return of spontaneous circulation and prognosis of cardiac arrest patients?

BACKGROUND

Early prediction of return of spontaneous circulation (ROSC) for cardiac arrest (CA) patients is a major challenge. Different biomarkers have been studied as an early predictor for ROSC, but a consensus has not been achieved in this regard. This study's goal was to investigate the value of the carboxyhaemoglobin (COHb) and methaemoglobin (MetHb) levels as a predictive marker for ROSC and prognostic marker for patients who achieve ROSC.

METHODS

A total of 241 adult patients (109 female, 132 male) diagnosed as non-traumatic CA were included in the study. The patients were divided into two groups based on whether they achieved ROSC. The ROSC group was divided into two sub-groups: survivors and non-survivors. Complete blood count parameters, routine biochemistry measurements, coagulation parameters, and blood gas analysis, and cardiac markers values were compared between the groups.

RESULTS

COHb levels were significantly lower in the non-ROSC group than in the ROSC group (P = .002). Urea, creatinine, potassium and cTn (cardiac troponin) levels in the non-ROSC group were significantly higher than in the ROSC group (P < .001, .001, .014, and .005, respectively). COHb levels were significantly lower in the non-survivor group than in the survivor group (P = .022). Urea, creatinine, potassium, lactate dehydrogenase, and cTn levels were significantly higher in the non-survivor group than the survivor group (P = .001, .005, .001, .010 and .008, respectively). There was no significant difference between the ROSC and non-ROSC groups and survivor group and non-survivor groups in terms of MetHb levels (P = .769 and .668, respectively). Moreover, CPR duration is significantly shorter in the survivor group than the non-survivor group (P ˂ .001).

CONCLUSION

COHb levels in the blood gas analysis at the time of admission could be used as a predictive marker for ROSC and prognostic marker for the patients who achieved ROSC.

Cardiovascular adverse events associated with smoking-cessation pharmacotherapies

Smoking continues to be the leading cause of preventable deaths in the USA, accounting for one in every five deaths every year, and cardiovascular (CV) disease remains the leading cause of those deaths. Hence, there is increasing awareness to quit smoking among the public and counseling plays an important role in smoking cessation. There are different pharmacological methods to help quit smoking that includes nicotine replacement products available over the counter, including patch, gum, and lozenges, to prescription medications, such as bupropion and varenicline. There have been reports of both nonserious and serious adverse CV events associated with the use of these different pharmacological methods, especially varenicline, which has been gaining media attention recently. Therefore, we systematically reviewed the various pharmacotherapies used in smoking cessation and analyzed the evidence behind these CV events reported with these therapeutic agents.

Nicotine replacement therapy and cardiovascular disease

Smoking is a well-established and important risk factor for cardiovascular disease. Cessation of smoking clearly decreases the chances of a first or subsequent cardiovascular event. Nicotine replacement therapy (NRT) is a proven adJunctive therapy to increase the probability of quitting smoking. Anecdotal reports of adverse events in patients using NRT have led some to question its safety. Is nicotine, whether in tobacco products or in NRT, the cause of the cardiovascular consequences associated with tobacco use? Is using NRT to assist with smoking cessation safer than smoking? Should health care professionals avoid recommending NRT for patients with established cardiovascular disease? This article summarizes the mechanisms of harm associated with smoking and reviews the safety of NRT in both the general population and the population with cardiovascular disease. Recommendations for NRT use are offered.

Post-myocardial infarction smoking cessation counseling: associations with immediate and late mortality in older Medicare patients

PURPOSE

To assess the difference in immediate (30 and 60 days after admission) and late (2-year) mortality between those who received inpatient post-myocardial infarction smoking cessation counseling and those who did not receive counseling.

METHODS

We conducted an observational study of a national random sample of inpatients from 2971 U.S. acute care hospitals participating in the Cooperative Cardiovascular Project in 1994-95. Medicare beneficiaries who were current smokers over age 65, admitted with a documented acute myocardial infarction, and who were discharged to home were included (n=16743). Our main outcome measures were early (30-, 60-day) and late (1-, 2-year) mortality.

RESULTS

Smoking cessation counseling was documented during their index hospitalization for 41% of patients. Compared with those not counseled, those who received inpatient counseling had lower 30-day (2.0% vs. 3.0%), 60-day (3.7% vs. 5.6%), and 2-year mortality (25.0% vs. 30%) (logrank P <0.0001). After adjustment for demographic characteristics, comorbid conditions, APACHE score, and receipt of treatments including aspirin, reperfusion, beta-blockers, and angiotensin-converting enzyme inhibitors, those receiving counseling were less likely to die within 1 year, but the effect was lost between 1 and 2 years [hazard ratio (HR) = 0.99 (0.91-1.10)]. The greatest reduction in relative hazard (19%) was seen within 30 days [HR = 0.81 (95% confidence interval 0.65-0.99)].

CONCLUSION

Immediate and long-term mortality rates were lower among those receiving inpatient smoking cessation counseling.

Effects of carbon monoxide inhalation during experimental endotoxemia in humans

Data show that carbon monoxide (CO) exerts direct antiinflammatory effects in vitro and in vivo after LPS challenge in a mouse model. We hypothesized that CO may act as an antiinflammatory agent in human endotoxemia. The aim of this trial was to study the effects of CO inhalation on cytokine production during experimental human endotoxemia. The main study was a randomized, double-blinded, placebo-controlled, two-way cross-over trial in healthy volunteers. Each volunteer inhaled synthetic air (as placebo) and 500 ppm CO for 1 hour in random order with a washout period of 6 weeks and received a 2-ng/kg intravenous bolus of LPS after inhalation. Carboxyhemoglobin levels were assessed as a safety parameter. CO inhalation increased carboxyhemoglobin levels from 1.2% (95% confidence interval, 1.0 to 1.4%) to peak values of 7.0% (95% confidence interval, 6.5 to 7.7%). LPS infusion transiently increased plasma concentrations of tumor necrosis factor-alpha, interleukin (IL)-6 (approximately 150-fold increases), and IL-8, as well as IL-1alpha and IL-1beta mRNA levels (an approximately 200-fold increase). These LPS-induced changes were not influenced by CO inhalation. Inhalation of 500 ppm CO for 1 hour had no antiinflammatory effects in a systemic inflammation model in humans, as 250 ppm for 1 hour did in rodents.

Comparison of cardioprotective effects using ramipril and DanShen for the treatment of acute myocardial infarction in rats

In the present study, we compared cardioprotective effects of DanShen (an extract from Salvia miltiorrhiza) and the angiotensin-converting enzyme inhibitor, ramipril, in rats. With both treatment regimens, DanShen- and ramipril similar effects were observed: (1) a higher survival rate, (2) a significant reduction of infarct size, (3) significantly lower ratios of heart weight to the body weight as well as the left and right ventricular weights to body weight. DanShen showed some unique effects in the following aspects: (1) higher activities of antioxidant defense enzymes such as superoxide dismutase (SOD), catalase (CAT), glutatione perioxidase (GSH-Px) and glutathione S-transferase (GST) in the liver of rats with acute myocardial infarction (AMI), (2) lower myocardial and hepatic TBARS values; (3) augmented VEGF mRNA expressions in the non-ischemic parts of rat hearts with AMI. These results were consistent with the findings of a slight increase in myocardial capillary density and the special distribution pattern of coronary blood vessels in DanShen-treated rats.

Neural circulatory responses to carbon monoxide in healthy humans

The contribution of carbon monoxide (CO) to the acute cardiovascular effects of smoking is not clear. Using a double-blind, randomized, vehicle-controlled study design, we examined the sympathetic and vascular responses to modest increases in carboxyhemoglobin in 10 healthy humans. We measured muscle sympathetic nerve activity (microneurography), forearm blood flow (plethysmography), heart rate, blood pressure, and minute ventilation at baseline and during 60 minutes of CO inhalation (1000 ppm during the first 30 minutes and 100 ppm during the last 30 minutes). The same measurements were made in a vehicle session (room air inhalation) on a separate day. During the first 30 minutes of CO inhalation, carboxyhemoglobin levels increased progressively from 0.2 +/- 0.1% to 8.3 +/- 0.5% and were maintained at about this level for a further 30 minutes. Forearm vascular resistance did not change with CO but increased slightly with vehicle; the effects of CO on muscle sympathetic nerve activity, forearm blood flow, blood pressure, heart rate, and minute ventilation were not significantly different from the effects of vehicle. Modest increases in carboxyhemoglobin levels equivalent to those resulting from cigarette smoking are unlikely to contribute to the acute sympathetic and hemodynamic effects of smoking in healthy humans.

Influence of carbon monoxide (CO) on the early course of acute myocardial infarction

OBJECTIVE

To clarify the influence of an elevated carboxyhemoglobin (COHb) blood level on the course of acute myocardial infarction and to evaluate the administration of supplemental oxygen on the COHb level and the incidence of complications.

DESIGN

Prospective clinical study with randomized, unblinded intervention.

SETTING

Coronary Care Unit of a university hospital.

PATIENTS

78 consecutive patients with acute myocardial infarction. Excluded were patients with severe dyspnea, pulmonary edema or any other medical indication for supplemental oxygen therapy.

INTERVENTIONS

Randomized therapy with 41/min oxygen in 35 patients.

MEASUREMENTS AND RESULTS

COHb was measured at admission and 4 h later. The incidence of serious arrhythmias and the maximal creatine kinase (CK) values were recorded. In patients with initial COHb > or = 5%, there were significantly more arrhythmias and significantly higher maximal CK values than in those with normal COHb admission (89 vs 33%, p < 0.001; and 1897 +/- 1602 u/l vs 960 +/- 1097 u/l, p=0.05). This effect was seen only in patients with Q-wave infarction, not in those with non-Q-wave infarction. Supplemental oxygen had no effect on the incidence of arrhythmias.

CONCLUSIONS

We conclude that myocardial infarction patients with acute Q-wave infarction and increased COHb levels at admission suffer a more severe course of the disease. This outcome was not influenced by oxygen therapy. Whether this finding indicates a casual relationship and whether higher oxygen concentrations would favorably alter the course of acute myocardial infarction remains to be determined.