Severe acute mountain sickness and suspect high altitude cerebral edema related to nitroglycerin use.

An elite mountaineer reported severe acute mountain sickness and ataxia during an 8000-m expedition and concomitant use of transdermal nitroglycerin patches aimed to prevent frostbites. Use of nitroglycerin for this purpose is off-label, and its safety has not been assessed. Moreover, a relation between nitrate-induced cerebral vasodilation and high altitude cerebral edema is theoretically possible on a pathophysiological basis.

Effects of altitude on effort tolerance in non-acclimatized patients with ischemic left ventricular dysfunction.

Background: Few studies exist on the effects, in terms of work capacity and safety, of exposure to moderately high altitudes in patients with stable ischemic left ventricular dysfunction. Moreover no data are currently available on the cardiorespiratory response to walks in the mountains.

Aim: The objective of this study is to evaluate the effects of altitude on effort tolerance during walks in the mountains and to determine whether exposure to altitude may be harmful to patients with ischemic left ventricular dysfunction.

Autonomic cardiovascular regulation in subjects with acute mountain sickness.

The aims of this study were 1) to evaluate whether subjects suffering from acute mountain sickness (AMS) during exposure to high altitude have signs of autonomic dysfunction and 2) to verify whether autonomic variables at low altitude may identify subjects who are prone to develop AMS. Forty-one mountaineers were studied at 4,559-m altitude. AMS was diagnosed using the Lake Louise score, and autonomic cardiovascular function was explored using spectral analysis of R-R interval and blood pressure (BP) variability on 10-min resting recordings.

["Bad" sleepers... Causes, effects, and diagnosis of sleep-related breathing disorders in cardiac patients].

Cardiovascular and cerebrovascular disease are the most common life-threatening disease in the industrialized world. There is high interest in sleep apnea and cardiovascular disease: several studies have demonstrated an association between sleep apnea and cardiovascular and cerebrovascular events. The aim of this review is to critically appraise the possible adverse physiological consequences of sleep apnea on the cardiovascular system and to assess whether such adverse effects constitute a risk for the development of cardiovascular disease.

[Altitude and the autonomic nervous system].

Ascent to high altitudes arouses the sympathetic nervous system in non-acclimatized healthy humans. Such activation is provoked by hypobaric hypoxia combined with other stressors. While this is an adaptive response, it also contributes to the general physical deterioration consequent to prolonged exposure to high altitudes, and is even implied in specific syndromes: acute mountain sickness, high altitude pulmonary edema (HAPE), and high altitude cerebral edema.

Comparison between spectral analysis and the phenylephrine method for the assessment of baroreflex sensitivity in chronic heart failure.

Baroreflex sensitivity assessed by means of the phenylephrine test plays a prognostic role in patients with previous myocardial infarction, but the need for drug injection limits the use of this technique. Recently, several non-invasive methods based on spectral analysis of systolic arterial pressure and heart period have been proposed, but their agreement with the phenylephrine test has not been investigated in patients with heart failure. The two methods (phenylephrine test and spectral analysis) were compared in a group of 49 patients with chronic congestive heart failure both at rest and during controlled breathing.

Prognostic value of nocturnal Cheyne-Stokes respiration in chronic heart failure.

Background: Nocturnal Cheyne-Stokes respiration (CSR) occurs frequently in patients with chronic heart failure (CHF), and it may be associated with sympathetic activation. The aim of the present study was to evaluate whether CSR could affect prognosis in patients with CHF.

Methods And Results: Sixty-two CHF patients with left ventricular ejection fraction View Article and Find Full Text PDF

Is heart rate variability a reliable method to assess autonomic modulation in left ventricular dysfunction and heart failure? Assessment of autonomic modulation with heart rate variability.

Autonomic dysfunction seems to be involved in the progression and prognosis of congestive heart failure. Measurement of heart rate variability (HRV) provides a noninvasive method to obtain reliable and reproducible information on autonomic modulation of heart rate, but there is a difficulty in using HRV as a quantitative estimate of autonomic dysfunction in heart failure. This study was aimed at testing the hypothesis that abnormal modulation of heart rate assessed by power spectrum analysis may be present also in asymptomatic patients with left ventricular dysfunction and progress in patients with overt symptoms of congestive heart failure.

Augmented peripheral chemosensitivity as a potential input to baroreflex impairment and autonomic imbalance in chronic heart failure.

Background: The precise mechanisms responsible for the sympathetic overactivity and blunted baroreflex control in chronic heart failure (CHF) remain obscure. Augmented peripheral chemosensitivity has recently been demonstrated in CHF. We evaluated the relation between peripheral chemoreflex sensitivity and autonomic activity in patients with CHF.

Chemoreceptor dependence of very low frequency rhythms in advanced chronic heart failure.

Factors responsible for very low frequency oscillations (VLF; cycle > 30 s) in the cardiovascular system remain obscure. We tested the hypothesis that increased peripheral chemosensitivity is important in the pathogenesis of VLF oscillations in patients with chronic heart failure (CHF). Fourteen male patients with stable, moderate to severe CHF (age 60 +/- 1.

Reproducibility of heart rate variability measures in patients with chronic heart failure.

1. In patients with chronic heart failure, heart rate variability is reduced with relative preservation of very-low-frequency power (< 0.04 Hz).

Detection and significance of a discrete very low frequency rhythm in RR interval variability in chronic congestive heart failure.

Although in advanced chronic congestive heart failure (CHF) very low frequency (< 0.04 Hz, VLF) oscillations are prominent, the clinical importance and the physiologic basis of these rhythms have not been elucidated. To investigate the physiologic determinants of the VLF rhythms in RR interval variability, we studied 36 patients with stable, moderate to severe CHF (33 men, age: 58 +/- 8 years, ejection fraction 25 +/- 10%, peak oxygen consumption 18.

Decreased heart rate variability in amyotrophic lateral sclerosis.

Autoregressive spectral analysis of heart rate variability (HRV) was performed in 29 patients with amyotrophic lateral sclerosis (ALS) and 33 age-matched healthy subjects to evaluate the involvement of the autonomic nervous system. HRV analysis provides a means to recognize low (LF) and high (HF) frequency components, respectively mediated by sympathetic and parasympathetic heart control. An increase in the mean heart rate at rest (P < 0.

Decreased heart rate variability in patients with chronic obstructive pulmonary disease.

To evaluate possible autonomic nervous system (ANS) dysfunction in patients with chronic obstructive pulmonary disease (COPD) in the absence of any hypoxic neuronal damage, we studied 31 patients with COPD patients aged 31 to 68 years (55 +/- 10) and 32 age-matched healthy subjects (control). Respiratory function in the patients was as follows: FEV1 = 52 +/- 8 percent; PaO2 = 71 +/- 14 mm Hg; and PaCO2 = 40 +/- 10 mm Hg. The ANS was assessed by heart rate variability (HRV) in the time domain (SD of mean RR interval) and frequency domain (autoregressive spectral analysis recognizing low [LF] and high [HF] frequency components, vagal and sympathetic related, respectively).

Long-term adaptation of 24-h heart rate variability after myocardial infarction. The EAMI Study Group. Exercise Training in Anterior Myocardial Infarction.

To investigate the effects of physical training on neurovegetative profile of patients with previous anterior myocardial infarction (MI), we studied 38 patients out of the EAMI study at 4 to 6 weeks after anterior MI (test 1), who were then assigned randomly to a training group (n = 22) or to a control group (n = 16) and studied again 6 months later (test 2). Neurovegetative function was assessed by analyzing the heart rate variability (HRV) of 24 h, from ambulatory ECG recording, both in time domain, as standard deviation of sinus rhythm RR intervals (sdRR) and percentage of differences greater than 50 ms for successive sinus rhythm R-R intervals (pNN50), and in frequency domain, as low frequency (LF) and high frequency (HF) components of RR variability power spectrum. At test 1, HRV was almost in normal range or slightly decreased in few subjects.

Sympathovagal interaction during mental stress. A study using spectral analysis of heart rate variability in healthy control subjects and patients with a prior myocardial infarction.

We tested the hypothesis that psychological stress testing in the clinical laboratory provokes changes in the sympathetic and vagal activities regulating heart rate that can be assessed noninvasively using spectral analysis of RR variability. To account for the effects on respiration produced by talking, this study was performed with two different procedures: the I.K.

Influence of mental stress on ventricular pump function in postinfarction patients. An invasive hemodynamic investigation.

To assess the influence of mental stress on ventricular pump function in coronary patients, 88 postinfarction patients (mean age, 53 +/- 10 years) performed mental arithmetic during Swan-Ganz catheterization monitoring a mean of 44 +/- 16 days after myocardial infarction. The test lasted 3 minutes in 66 patients and 10 minutes in 22 patients. Two patients suffered acute pulmonary edema a few minutes after mental arithmetic, but no others complained of symptoms.

[The association of arithmetic calculation and noise as a mental stressor in the functional evaluation of recent myocardial infarction].

To evaluate the possible augmented power of mental arithmetic when given to the subjects during noise, 12 postinfarct patients underwent mental arithmetic in the standard way and then the same stressor with a white noise: mental arithmetic significantly increased (p less than 0.05) the heart rate, while mental arithmetic and white noise significantly increased (p less than 0.05) heart rate, systolic and mean blood pressure, as well as skin conductance.

[Stroop's color-word test as a mental stressor in the functional evaluation of recent myocardial infarction: comparison with arithmetic calculation].

To assess the power of Stroop's color-word test to induce cardiovascular arousal in cardiac patients, 10 postinfarct patients underwent Stroop's test, as well as the mental arithmetic test, which was assumed to be the gold standard. Both stressors induced significant increases in heart rate and blood pressure; the differences between these increases were not statistically significant. Stroop's test is a useful alternative to the mental arithmetic test in the study of cardiovascular responses to mental stress.

Hemodynamic response to different types of mental stress in patients with recent myocardial infarction.

The purpose of this study was to analyze the cardiovascular effects induced by mental stress evoked by different stressors in patients with recent uncomplicated myocardial infarction. Twenty four males, aged 52 +/- 10 years, were studied 45 +/- 22 days after uncomplicated myocardial infarction in the absence of specific cardiovascular drugs. During electrocardiographic and hemodynamic monitoring with a Swan-Ganz catheter the patients underwent 4 different stressors: mental arithmetic, Sacks test, Raven progressive matrices, white noise.

Effects of propranolol, atenolol, and chlordesmethyldiazepam on response to mental stress in patients with recent myocardial infarction.

Stress testing was carried out by two stressors, mental arithmetic and Sacks-Levy's test in randomized sequence, in 64 male patients with a mean age of 51 +/- 7 years in NYHA Classes I or II within 3 months after acute myocardial infarction. The stress profile was obtained after drug withdrawal by continuous recording of electrocardiogram, frontal electromyogram, and peripheral skin temperature and conductance. Blood pressure was measured each minute by cuff.