Coronary flow, VO2 peak and anaerobic threshold in patients with dilated cardiomyopathy.

BACKGROUND: Coronary flow is influenced by several determinants and may change according to external stimuli. In patients with dilated cardiomyopathy (DC), adaptive mechanisms could induce alterations in coronary flow, possibly related to oxygen consumption. METHODS: In 67 consecutive patients with DC (mean age 52.06+/-13.84, 52 male gender, left ventricle ejection fraction (LVEF) 29.49%+/-8.68) and normal coronary angiography findings, coronary flow in left anterior descending (LAD), right coronary artery (RC) and left circumflex (LCx) was reported as TIMI frame count (TFC). All patients underwent a cardiopulmonary test with VO2 peak and anaerobic threshold (AT) measurement, New York Heart Association (NYHA) class stratification, two-dimensional echocardiographic evaluation including LVEF and left ventricle end-diastolic diameter (LVEDD) assessment. All patients were receiving optimal medical treatment. RESULTS: In a multivariate analysis, a statistically significant correlation was found between VO2 peak and TFC (B 7.61, p<0.001, R2 0.61 for LAD; B 3.42, p<0.001, R2 0.33 for RC); an inverse correlation was found between AT and TFC (B -9.77, p<0.001, R2 0.61 for LAD; B -4.26, p<0.001, R2 0.33 for RC). CONCLUSIONS: Coronary flow is related to VO2 peak and AT in patients with DC, suggesting a "compensatory" mechanism.

Management of patients with syncope referred urgently to general hospitals.

OBJECTIVE: To evaluate the incidence and the strategy of management of syncope admitted urgently to a general hospital. BACKGROUND: The management of patients with syncope is not standardized. METHODS: The study was a prospective observational registry from a sample of 28 general hospitals in Italy and enroled all consecutive patients referred to their emergency rooms from November 5th 2001 to December 7th 2001 who were affected by transient loss of consciousness as the principal symptom. RESULTS: The incidence of syncope was 0.95% (996 of 105,173 patients attending). Forty-six percent were hospitalized, mostly in the Department of Internal Medicine. The mean in-hospital stay was 8.1+/-5.9 days. A mean of 3.48 tests was performed per patient. A definite diagnosis was made in 80% of cases, neurally-mediated syncope being the most frequent. The findings of each of the 28 hospitals participating in the survey were separately evaluated. We observed great inter-hospital and inter-department heterogeneity regarding the incidence of emergency admission, in-hospital pathways, most of the examinations performed and the final assigned diagnosis. For example, the execution of carotid sinus massage ranged from 0% in one hospital to 58% in another (median 12.5%); tilt testing ranged from 0 to 50% (median 5.8%); the final diagnosis of neurally-mediated syncope ranged from 10 to 78.6% (median 43.3%). CONCLUSION: Great inter-hospital and inter-department heterogeneity in the incidence and management of syncope was observed in general hospitals. As a consequence, we were unable to describe a uniform strategy for the management of syncope in everyday practice.

Free testosterone plasma levels are negatively associated with the intima-media thickness of the common carotid artery in overweight and obese glucose-tolerant young adult men.

OBJECTIVE: To evaluate the relation between free testosterone (FT) levels and the intima-media thickness of the common carotid artery (IMT-CCA) in overweight and obese glucose-tolerant (NGT) young adult men. DESIGN: Cross-sectional study of FT and IMT-CCA in obese men. SUBJECTS: A total of 127 overweight and obese NGT male individuals, aged 18-45 y. MEASUREMENTS: FT plasma levels; IMT-CCA, as measured by high-resolution B-mode ultrasound imaging; central fat accumulation, as evaluated by waist circumference; body composition, as measured by bioimpedance analysis; insulin resistance, as calculated by homeostatic model assessment (HOMA(IR)); systolic and diastolic blood pressure; and fasting concentrations of glucose, insulin, and lipids. RESULTS: IMT-CCA was positively correlated with age, body mass index (BMI), fat mass (FM), waist circumference, and fasting glucose concentrations, and inversely associated with FT levels. After multivariate analysis, IMT-CCA maintained an independent association with BMI, FM, and FT levels. This study indicates that IMT-CCA is negatively associated with FT levels, independent of age, total body fat, central fat accumulation, and fasting glucose concentrations in overweight and obese NGT patients. CONCLUSION: Hypotestosteronemia may accelerate the development of atherosclerosis and increase the risk for CHD in obese men.

Whole-body bioelectrical impedance analysis in patients with chronic heart failure: reproducibility of the method and effects of body side.

BACKGROUND: Fluid imbalance and malnutrition have an important role in the clinical setting of chronic heart failure (CHF). Recently, tetrapolar bioelectrical impedance analysis has been suggested as an attractive method which may be used in the clinical assessment of the body composition. The aim of this study was to determine the effects of body side on whole bioelectrical impedance analysis parameters and test-retest reliability, prior to its use in a large cohort of patients. METHODS: In 114 consecutive patients with CHF (mean age 65 +/- 10 years, left ventricular ejection fraction 31 +/- 9%, NYHA functional class 2.6 +/- 0.9) we measured the total body resistance, the reactance and the derived angle phase using a single-frequency (50 KHz) tetrapolar plethysmograph device. The evaluations were performed on the left and right sides of the body, in a random order, on two different occasions 30 min apart. The effects of body side were analyzed by the Student's t-test and the test-retest reliability was computed by using the coefficient of variation and intraclass correlation coefficient. RESULTS: In both evaluations, the mean resistance value of the right side was significantly lower (almost 10 ohms) than that of the left side, the reactance was not different, and as a consequence the angle phase was significantly higher (almost 0.1 degrees) in the right than in the left side. The test-retest reliability for all the measurements considered was very high (the intraclass correlation coefficient ranged from 0.95 to 0.99 and the coefficient of variation from 1.7 to 4.3%). CONCLUSIONS: In CHF, the body side is important for the whole-body assessment of the resistance and the angle phase, but not for reactance. In addition, all these measurements are characterized by an excellent test-retest reliability and, consequently, do not necessitate a substantial increase in the sample size for the detection of small differences in experimental studies.

Plasma leptin is independently associated with the intima-media thickness of the common carotid artery.

OBJECTIVE: To investigate whether intima-media thickness (IMT) of the common carotid artery (CCA), an early marker of asymptomatic atherosclerosis, is significantly and independently associated with plasma concentrations of leptin, an adipose tissue hormone that has recently been proposed as a cardiovascular risk factor in obese patients. DESIGN: Cross-sectional sample of normal-weight and obese men and women. SUBJECTS: One-hundred and twenty healthy subjects (52 men and 68 women), aged 18-45 y and with a wide range of BMI, were recruited for the study. MEASUREMENTS: Fasting plasma leptin concentrations and the IMT of the CCA were measured in all subjects. Leptin concentrations were measured by radioimmunoassay and the IMT of the CCA was quantified by high resolution B-mode ultrasound imaging. Central fat (measured by waist circumference), smoking habits, blood pressure, insulin sensitivity (measured by the insulin tolerance test), and fasting plasma glucose, insulin and lipid pattern (cholesterol, HDL-cholesterol, triglycerides, LDL-cholesterol) were also measured. RESULTS: IMT of the CCA was positively correlated with log leptin concentrations (P<0.005 in men and P<0.001 in women), body mass index (P<0.001 in men and women), waist circumference (P<0.001 in men and women), age (P<0.001 in men and P<0.05 in women), and negatively associated with insulin sensitivity in both sexes (P<0.05). IMT was also directly correlated with cholesterol (P<0.05), LDL-cholesterol (P<0.01) and systolic blood pressure in men (P<0.05), and with diastolic blood pressure levels in women (P<0.05). When a multiple linear regression model was used without body mass index (BMI), the correlation between leptin and IMT was maintained in both men (P<0.01) and women (P<0.005), independent of age, insulin sensitivity, smoking habits, systolic blood pressure, fasting glucose, triglycerides, cholesterol, LDL-cholesterol and HDL-cholesterol. By contrast, BMI-adjusted leptin concentrations were not significantly associated with IMT (Pc (partial correlation): 0.41 in men and 0.15 in women). Moreover, when BMI was entered into a multiple linear regression model without leptin, the correlation between BMI and IMT was maintained in both men (P<0.005) and women (P<0.01), independent of the same parameters. CONCLUSION: Plasma leptin concentrations are independently associated with the IMT of the CCA, suggesting that the increase of adipose tissue mass (or leptin per se) may have an unfavourable influence on the development of atherosclerosis. However, the association between IMT and leptin seems to be dependent and/or confounded by the relationship between IMT and obesity.

[Cardiopulmonary sensitivity and chemosensitivity]. / Sensibilità cardiopolmonare e chemosensibilità.

The autonomic control of the cardiovascular system plays an important role in maintaining the arterial pressure at the levels necessary for adequate tissue perfusion. In cardiovascular diseases, the impairment of the basic reflex mechanisms that are responsible for the moment-to-moment regulation could increase sympathetic activity and is correlated with an adverse outcome. The objective of the present review was to provide information about the methodological aspects exploring cardiopulmonary and chemoreceptor reflexes. Different techniques are available and all of them include assessment of reflexes through the activation or deactivation of either the cardiopulmonary baroreceptors or chemoreceptors. Intravenous saline load, head-down tilt, passive legs raising, head-out water immersion and the application of a lower body positive pressure are the principal methods utilized for activating cardiopulmonary baroreceptors; on the contrary deactivation could be achieved by acutely induced hypovolemia by furosemide or blood donation, inflation of a congestion cuff on the thighs or application of a negative pressure on the lower body. The transient exposure to a hypoxic or a hypercapnic gas mixture is frequently used to determine the peripheral and central chemoreflexes, respectively. The reflexes are quantified by the gain between output (i.e. heart rate, sympathetic activity, vascular resistance, ventilation) and input (oxygen saturation, end-tidal CO2 or changes in central venous pressure). One important limitation in assessing the cardiopulmonary baroreflex by using currently available techniques is that the involvement of the arterial baroreflex cannot be avoided. In addition, chemoreflexes cannot be interpreted unless the breathing rate is controlled. To date, several techniques are available for the quantification of cardiopulmonary baroreceptor and chemoreceptor reflexes and could provide new information on the abnormal autonomic mechanisms contributing to the pathophysiology of several cardiovascular diseases.

Ticlopidine versus aspirin after myocardial infarction (STAMI) trial.

OBJECTIVES: We sought to compare the efficacy of aspirin and ticlopidine in survivors of acute myocardial infarction (AMI) treated with thrombolysis. BACKGROUND: The role of ticlopidine in secondary prevention after AMI has not yet been explored. METHODS: Of 4,696 patients with AMI treated with thrombolysis who were screened, 261 died in the hospital (5.6%) and 1,470 were enrolled in this randomized, double-blind, multicenter trial and allocated to treatment with either aspirin (160 mg/day) or ticlopidine (500 mg/day). The most frequent reasons for exclusion were refusal to give informed consent, planned myocardial revascularization, risk of noncompliance with study procedures, need for anticoagulant therapy and contraindications to the study treatments. The primary end point was the first occurrence of any of the following events during the six-month follow-up: fatal and nonfatal AMI, fatal and nonfatal stroke, angina with objective evidence of myocardial ischemia, vascular death or death due to any other cause. RESULTS: The primary end point was recorded in 59 (8.0%) of the 736 aspirin-treated and 59 (8.0%) of the 734 ticlopidine-treated patients (p = 0.966). Vascular death was the first event in five patients taking aspirin and in six patients taking ticlopidine (0.7% vs. 0.8%; p = NS); nonfatal AMI in 18 and 8 (2.4% vs. 1.1%; p = 0.049); nonfatal stroke in 3 and 4 (0.4% vs. 0.5%; p = NS); and angina in 33 and 40 (4.5% vs. 5.4%; p = NS), respectively. The frequency of adverse reactions was not significantly different between the two groups. CONCLUSIONS: No difference was found between the ticlopidine and aspirin groups in the rate of the primary combined end point of death, recurrent AMI, stroke and angina.

Depression but not anxiety influences the autonomic control of heart rate after myocardial infarction.

AIMS: It has been previously hypothesized that the adverse outcome observed in depressed patients after myocardial infarction might be due to an imbalance in autonomic nervous system activity. The aim of this study was to define the role of depressive and anxious symptoms in influencing autonomic control of heart rate after myocardial infarction. METHODS AND RESULTS: The SD of RR intervals, baroreflex sensitivity, and depression and anxiety (Zung's scales) were assessed before discharge in 103 patients with acute myocardial infarction; 32 were found to be depressed. Among the patients who were not taking beta-blockers, those with depression had significantly lower SDs of RR intervals and baroreflex sensitivity than did those without depression (96.3 +/- 22.2 ms vs 119.5 +/- 37.7 ms, P =.016; 8.6 +/- 6.2 ms vs 11.8 +/- 6.5 ms/mm Hg, P =.01, respectively). No differences were found when anxiety was considered or when beta-blockers were given. Among the patients not taking beta-blockers, there was a significant correlation between depression levels and both the SD of RR intervals (r = -0.47) and baroreflex sensitivity (r = -0.40). CONCLUSIONS: In patients with myocardial infarction, depression but not anxiety negatively influences autonomic control of heart rate. Beta-blockers modify these influences.

Usefulness of handgrip to improve ibutilide efficacy in organizing atrial electrical activity during atrial fibrillation.

We analyzed the effect of handgrip on atrial electrical activity during atrial fibrillation (AF) by recording right and left atrial activity in 15 patients with persistent AF under baseline conditions and after saline and ibutilide infusions. The handgrip test for 15 seconds, which was always associated with a significant increase in mean atrial cycle length, was recorded in both atria (right atrium: saline vs saline + handgrip 141 +/- 29 vs 171 +/- 24 ms, p <0.001; ibutilide vs ibutilide + handgrip: 197 +/- 43 vs 221 +/- 39 ms, p <0.005). Handgrip favorably modifies atrial electrophysiologic properties during AF.

Effect of intermittent subdiastolic pressure in thigh cuffs on human arterial baroreflex.

BACKGROUND: We investigated the effects of subdiastolic variations of the pressure inside the thigh cuffs on cardiovascular oscillations and arterial baroreflex sensitivity in humans. METHODS: During 10 min of controlled breathing at low (0.1 Hz) and high (0.25 Hz) frequencies, 30 healthy subjects underwent variations of the pressure inside the thigh cuffs (from 0 to 40 mmHg) at 0.25 and 0.1 Hz respectively; the periods of controlled breathing without cuff pressure modulation were used as a control. The frequency responses of cardiovascular signals were assessed using spectral analysis, and baroreflex sensitivity by the sequence method. RESULTS: Cuff pressure modulation at 0.25 Hz did not affect the RR interval, arterial pressure, or baroreflex sensitivity; at 0.1 Hz it did not change the RR interval and arterial pressure, but engaged (0.76 +/- 0.2 of coherence) and increased the low frequency oscillations of the RR interval (from 5.6 +/- 1 to 6.1 +/- 0.9 ln ms2, p < 0.05) and improved baroreflex sensitivity by 25% (from 14.2 +/- 9 to 17.7 +/- 10 ms/mmHg, p < 0.01). CONCLUSIONS: Subdiastolic thigh cuff pressure modulation at 0.1 Hz improved the low frequency oscillations of heart rate and baroreflex sensitivity. This approach represents a new and simple non-pharmacological strategy for acutely improving baroreflex sensitivity in humans.