Prognostic value of baroreflex sensitivity assessed by phase IV of Valsalva manoeuvre in patients with mild-to-moderate heart failure

Correlation of the New York Heart Association Classification and the 6-Minute Walk Distance: A Systematic Review

BACKGROUND

Functional status assessment is the cornerstone of heart failure management and trials. The New York Heart Association (NYHA) classification and 6-minute walk distance (6MWD) are commonly used tools; however, the correlation between them is not well understood.

HYPOTHESIS

We hypothesised that the relationship between the NYHA classification and 6MWD might vary across studies.

METHODS

A systematic literature search was performed to identify all studies reporting both NYHA class and 6MWD. Two reviewers independently assessed study eligibility and extracted data. Thirty-seven studies involving 5678 patients were included.

RESULTS

There was significant heterogeneity across studies in 6MWD within all NYHA classes: I (n = 16, Q = 934.2; P < 0.001), II (n = 25, Q = 1658.3; P < 0.001), III (n = 30, Q = 1020.1; P < 0.001), and IV (n = 6, Q = 335.5; P < 0.001). There was no significant difference in average 6MWD between NYHA I and II (420 m vs 393 m; P = 0.416). There was a significant difference in average 6MWD between NYHA II and III (393 m vs 321 m; P = 0.014) and III and IV (321 m vs 224 m; P = 0.027). This remained significant after adjusting for region of study, age, and sex.

CONCLUSIONS

Although there is an inverse correlation between NYHA II-IV and 6MWD, there is significant heterogeneity across studies in 6MWD within each NYHA class and overlap in 6MWD between NYHA I and II. The NYHA classification performs well in more symptomatic patients (NYHA III/IV) but less so in asymptomatic/mildly symptomatic patients (NYHA I/II). Nonetheless, the NYHA classification is an easily applied first-line tool in everyday clinical practice, but its potential subjectivity should be considered when performing comparisons across studies.

Prognostic significance of impaired baroreflex sensitivity assessed from Phase IV of the Valsalva maneuver in a population-based sample of middle-aged subjects

Depressed baroreflex sensitivity (BRS) is associated with an increased risk of mortality in patients with a known cardiac disease. The prognostic significance of BRS in subjects without history of major cardiovascular (CV) events is unknown. The present study tested the hypothesis that impaired BRS predicts the CV mortality in a population-based sample of middle-aged subjects. The present study is a part of the Oulu Project Elucidating Risk of Atherosclerosis study, where middle-aged hypertensive and age- and gender-matched control subjects were randomly selected. Along with clinical and laboratory assessments, BRS was measured from the blood pressure overshoot of Valsalva maneuver in 559 subjects (age 51 ± 6 years; 300 men). The causes of death (n = 72) were registered during a follow-up of up to 19 years. CV death (n = 23) was defined as the primary end point. CV death was predicted by smoking status, alcohol consumption, high-sensitivity C-reactive protein, use of diuretics, waist circumference, and fasting glucose. Among all measured risk factors, impaired Valsalva BRS (<3 ms/mm Hg) was the most potent predictor of CV death (hazard ratio 9.1, 95% confidence interval 3.8 to 21.7, p <0.001) and remained so after adjustments for the other significant predictors (hazard ratio 5.3, 95% confidence interval 2.1 to 13.3, p <0.001). In conclusion, impaired Valsalva BRS is a potent and independent predictor of CV death in a population-based sample of middle-aged subjects without history of major CV complications and may have important clinical implications in early risk stratification.

Terminalia arjuna enhances baroreflex sensitivity and myocardial function in isoproterenol-induced chronic heart failure rats

Chronic heart failure (CHF) is characterized by left ventricular (LV) dysfunction along with impaired autonomic control functions. Herbal drugs are increasingly being used in the treatment of cardiovascular disorders. The present study was designed to examine the protective effect of Terminalia arjuna (T arjuna) bark extract on LV and baroreflex function in CHF and to elucidate the possible mechanistic clues in its cardioprotective action. The baroreflex was evaluated by measuring the changes in heart rate (HR) with changes in arterial blood pressure induced by bolus injections of phenylephrine (vasoconstrictor) and sodium nitroprusside (vasodilator). T arjuna bark extract and fluvastatin were tested/administered therapeutically and prophylactically in isoproterenol-induced rat model of CHF. Fifteen days after isoproterenol administration, rats exhibited cardiac dysfunction, hypertrophy, and LV remodeling along with reduced baroreflex sensitivity. Prophylactic and therapeutic treatment with T arjuna improved cardiac functions and baroreflex sensitivity. It also attenuated hypertrophy and fibrosis of the LV. Fluvastatin treatment exerted a similar protective effect against myocardial remodeling and heart failure. Further, T arjuna and fluvastatin significantly reduced oxidative stress and inflammatory cytokine level in CHF rats. In conclusion, T arjuna exerts beneficial effect on LV functions, myocardial remodeling, and autonomic control in CHF possibly through maintaining endogenous antioxidant enzyme activities, inhibiting lipid peroxidation and cytokine levels.

Baroreflex sensitivity: measurement and clinical implications

Alterations of the baroreceptor-heart rate reflex (baroreflex sensitivity, BRS) contribute to the reciprocal reduction of parasympathetic activity and increase of sympathetic activity that accompany the development and progression of cardiovascular diseases. Therefore, the measurement of the baroreflex is a source of valuable information in the clinical management of cardiac disease patients, particularly in risk stratification. This article briefly recalls the pathophysiological background of baroreflex control, and reviews the most relevant methods that have been developed so far for the measurement of BRS. They include three "classic" methods: (i) the use of vasoactive drugs, particularly the alpha-adrenoreceptor agonist phenylephrine, (ii) the Valsalva maneuver, which produces a natural challenge for the baroreceptors by voluntarily increasing intrathoracic and abdominal pressure through straining, and (iii) the neck chamber technique, which allows a selective activation/deactivation of carotid baroreceptors by application of a negative/positive pressure to the neck region. Two more recent methods based on the analysis of spontaneous oscillations of systolic arterial pressure and RR interval are also reviewed: (i) the sequence method, which analyzes the relationship between increasing/decreasing ramps of blood pressure and related increasing/decreasing changes in RR interval through linear regression, and (ii) spectral methods, which assess the relationship (in terms of gain) between specific oscillatory components of the two signals. The limitations of the coherence criterion for the computation of spectral BRS are discussed, and recent proposals for overcoming them are presented. Most relevant clinical applications of BRS measurement are finally reviewed with particular reference to patients with myocardial infarction and heart failure.

Teaching cardiac autonomic function dynamics employing the Valsalva (Valsalva-Weber) maneuver

In this report, a brief history of the Valsalva (Valsalva-Weber) maneuver is outlined, followed by an explanation on the use of this approach for the evaluation of cardiac autonomic function based on underlying heart rate changes. The most important methodological and interpretative aspects of the Valsalva-Weber maneuver are critically updated, and some guidelines are established for simple application of the maneuver in a teaching or research laboratory setting. These include the hemodynamic and cardiac autonomic mechanisms involved, technical aspects such as the intensity and duration of the expiratory straining, frequency of maneuver sessions, training and posture of the individuals tested, different time- and grade change-dependent indexes of heart interval variation, and clinical application of the maneuver.

Triggers of acute pulmonary thromboembolism developed in hospital, with focusing on toilet activities as triggering acts

BACKGROUND

The recognition of the trigger which is the action leading to the occurrence of acute pulmonary thromboembolism (APTE) is important to perform early diagnosis and early management of APTE.

METHODS AND RESULTS

The trigger of APTE in 138 patients who developed APTE in hospital was investigated. The triggers of APTE were specified in 57 patients. Approximately half of these patients developed APTE during toilet activities (defecation and micturition). Mortality of the patients with APTE associated with toilet activities was 33%. APTE associated with toilet activities was independently related to a recent major surgery, heart diseases and a recent angiography.

CONCLUSIONS

Defecation and micturition would be common triggers of APTE after operation and angiography, especially in patients with cardiac dysfunction.