Respiratory patterns and baroreflex function in heart failure.

Little is known on the effects of respiratory patterns on baroreflex function in heart failure (HF). Patients with HF (n = 30, age 61.6 ± 10 years, mean ± SD) and healthy controls (CNT, n = 10, age 58.9 ± 5.6 years) having their R-R interval (RRI, EKG), systolic arterial blood pressure (SBP, Finapres) and respiratory signal (RSP, Respitrace) monitored, were subjected to three recording sessions: free-breathing, fast- (≥ 12 bpm) and slow- (6 bpm) paced breathing. Baroreflex sensitivity (BRS) and power spectra of RRI, SBP, and RSP signals were calculated. During free-breathing, compared to CNT, HF patients showed a significantly greater modulation of respiratory volumes in the very-low-frequency (< 0.04 Hz) range and their BRS was not significantly different from that of CNT. During fast-paced breathing, when very-low-frequency modulations of respiration were reduced, BRS of HF patients was significantly lower than that of CNT and lower than during free breathing. During slow-paced breathing, BRS became again significantly higher than during fast breathing. In conclusion: (1) in free-breathing HF patients is present a greater modulation of respiratory volumes in the very-low-frequency range; (2) in HF patients modulation of respiration in the very-low and low frequency (around 0.1 Hz) ranges contributes to preserve baroreflex-mediated control of heart rate.

Ventricular Arrhythmias and Implantable Cardioverter-Defibrillator Therapy in Women: A Propensity Score-Matched Analysis.

BACKGROUND: Causes of sex differences in incidence of sustained ventricular arrhythmias (SVAs) are poorly understood. OBJECTIVES: This study aims to investigate sex-specific risk of SVAs and device therapies by balancing sex groups in relation to several baseline characteristics with the propensity score (PS). METHODS: We used a large remote monitoring dataset from implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds). Study endpoints were time to the first appropriate SVA, time to the first device therapy for SVA, and time to the first ICD shock. Results were compared between females and a PS-matched male subgroup. RESULTS: In a cohort of 2,532 patients with an ICD or CRT-D (median age, 70 years), 488 patients (19.3%) were women. After selecting 488 men PS-matched for 19 variables relative to baseline demographics, implant indications, principal comorbidities, and concomitant therapy, yet the SVA rate at the 2.1-year median follow-up was significantly lower in women than in man (adjusted HR: 0.65; 95% CI: 0.51-0.81; P < 0.001). Women also showed a reduced risk of any device therapy (HR: 0.59; 95% CI: 0.45-0.76; P < 0.001) and shocks (HR: 0.66; 95% CI: 0.47-0.94; P = 0.021). Differences in sex-specific SVA risk profile were not confirmed in CRT-D patients (HR: 0.78; 95% CI: 0.55-1.09; P = 0.14) nor in those with an ejection fraction <30% (HR: 0.80; 95% CI: 0.52-1.23; P = 0.31). CONCLUSIONS: After matching demographics, indications, principal comorbidities, and concomitant therapy, women still exhibited a lower SVA risk profile than men, except in the subgroups of CRT-D or/and ejection fraction <30%.

Cardiovascular variability is similarly altered in coronary patients with normal left ventricular function and in heart failure patients.

OBJECTIVE: After myocardial infarction (MI), baroreflex function is impaired and heart rate (HR) variability is reduced. An impaired baroreflex has been observed also in coronary patients with no previous MI, leading to hypothesize alterations of HR variability also in these patients. The aim of the present work was, therefore, to study whether and to what extent cardiovascular variability is altered in coronary patients with no previous MI. METHODS: Thirty-two individuals were studied: eleven patients with coronary artery disease but no previous MI [coronary artery disease (CAD)], eleven patients with a reduced left ventricular ejection fraction [congestive heart failure (CHF)] and ten age-matched controls (CNT). RESULTS: Overall HR variability was significantly and similarly reduced in CAD (630 ±â€Š272 ms) and CHF patients (594 ±â€Š395 ms) with respect to CNT (1405 ±â€Š837 ms), this being the case also for the low and high frequency spectral components. Low-frequency oscillations of blood pressure (BP) were also significantly and similarly less pronounced in CAD (0.7 ±â€Š0.7 mmHg) and CHF patients (0.7 ±â€Š0.7 mmHg) compared with CNT (1.8 ±â€Š1.4 mmHg). Moreover, both CAD and CHF patients showed a significantly reduced baroreflex function and an increased pulse-wave velocity with respect to CNT. CONCLUSION: Our study shows that in coronary patients with no MI and no left ventricular dysfunction, there is a profound alteration of both HR and BP variability as in CHF patients, presumably because of a marked impairment of the autonomic modulation of the heart and blood vessels.

Increased pulse wave velocity and not reduced ejection fraction is associated with impaired baroreflex control of heart rate in congestive heart failure.

BACKGROUND: It is known that baroreflex sensitivity (BRS) is impaired in cardiac patients with myocardial infarction (MI). Nevertheless, it is unknown whether factors other than a reduced ejection fraction play a role in the baroreflex impairment of these patients. METHODS AND RESULTS: Heart failure patients [congestive heart failure (CHF), n = 31, age 63 +/- 1.2 years, mean +/- SEM)], age-matched controls (n = 29) and coronary artery disease (CAD) patients without MI (n = 29) had RR interval and arterial blood pressure (BP) continuously monitored. Baroreflex function was assessed by the slope of the regression of RR interval, and BP responses to graded (-10, -20 and -40 mmHg) neck suction stimulation, the slope of bradycardic or tachycardic responses to spontaneous increases or reductions of SBP (sequence analysis) and the baroreflex efficiency index. Pulse wave velocity (PWV) was also measured.Compared with controls, CHF patients had RR interval and BP reflex responses to neck suction reduced by -36 and -54%, respectively (P < 0.01). By contrast, no differences were found between CHF and CAD patients. Similar reductions were observed for the sequence analysis (P < 0.01) in both CHF and CAD patients. Multiple regression analysis showed that in CHF and CAD patients, PWV and SBP and not ejection fraction were correlated with BRS. CONCLUSION: The baroreflex function is impaired in CHF patients, the extent and the degree of baroreflex impairment being similar to that of CAD patients without MI. In CHF and CAD patients, the baroreflex impairment correlates significantly with the increased PWV and not with ejection fraction.

Inflammatory activation during coronary artery surgery and its dose-dependent modulation by statin/ACE-inhibitor combination.

BACKGROUND: On-pump coronary artery bypass graft (CABG) surgery triggers an inflammatory response (IR) which may impair revascularization. The study aimed at (1) characterizing the temporal profile of the IR by assaying appropriate markers in both systemic and coronary blood, and (2) determining whether (and which doses of) cardiovascular drugs known to have antiinflammatory properties, namely statins and ACE-inhibitors (ACEI), inhibit the response. METHODS AND RESULTS: Patients scheduled for CABG (n=22) were randomized to statin/ACEI combination treatment at standard doses (STD, ramipril 2.5/simvastatin 20 mg, or atorvastatin 10 mg), or at high doses (HiDo, ramipril 10 mg, or enalapril 20 mg/simvastatin 80 mg, or atorvastatin 40 mg). Plasma levels of interleukin 6, tumor necrosis factor alpha, E-selectin, von Willebrand factor (vWF), and sVCAM-1 were serially assayed (ELISA) before, during, and after CABG. Blood was drawn from an artery, a systemic vein, and the coronary sinus. Myocardial perfusion scans were obtained before and 2 months after surgery in 19 out of 22 subjects. In the STD group both IL-6 and TNF displayed striking increases which were similar at all sites and peaked 10 to 60 minutes after aortic declamping. Such increases were drastically attenuated in the HiDo group. Instead, only modest increases in venous E-selectin, vWF, and sVCAM-1 were observed. Scintigraphic ischemia scores were entirely normalized after versus before CABG in the HiDo but not in the STD treatment group. CONCLUSIONS: On-pump CABG surgery is associated with an intense systemic inflammatory response, which can be almost completely prevented by early treatment with high (but not standard) doses of ACE-inhibitors and statins.

Enhanced baroreceptor control of the cardiovascular system by polyunsaturated Fatty acids in heart failure patients.

OBJECTIVES: The intention of this study was to test the hypothesis that, in heart failure patients, dietary supplementation of polyunsaturated fatty acids (PUFA) enhances arterial baroreceptor control of the cardiovascular system. BACKGROUND: Administration of PUFA reduces the risk of life-threatening arrhythmias in patients surviving myocardial infarction. This might result from potentiation of arterial baroreflexes, but whether or not PUFA enhance baroreflex function has never been studied in humans. METHODS: Patients with post-myocardial infarction left ventricular dysfunction underwent beat-to-beat blood pressure (BP) (Finapres, Ohmeda Inc., Englewood, Colorado) and R-R interval (electrocardiogram) recording; baroreceptor reflexes were assessed from the bradycardic and depressor responses to graded neck suction (NS) as well as by computation of the alpha "spontaneous" baroreflex sensitivity index. Assessments were repeated after prolonged treatment with PUFA (2 g/die, n = 15) or placebo (n = 10). RESULTS: Baseline BP and R-R interval were unaffected by PUFA. Both reflex depressor and bradycardic responses to NS increased after PUFA (respectively from -0.09 +/- 0.01 to -0.16 +/- 0.01 mm Hg x mm Hg(-1), p < 0.01, and from 1.25 +/- 0.9 to 1.76 +/- 1.1 ms x mm Hg(-1), p < 0.04) but not after placebo. The spontaneous baroreflex sensitivity increased in the PUFA (from 8.99 +/- 1.4 to 12.2 +/- 1.2 ms x mm Hg(-1), p < 0.02) but not in the placebo group. Polyunsaturated fatty acids (but not placebo) treatment also significantly increased R-R interval total variance and low-frequency and high-frequency spectral powers. CONCLUSIONS: Dietary PUFA supplementation markedly potentiates baroreflex function and enhances heart rate variability in patients with stable congestive heart failure.

Adrenergic origin of very low-frequency blood pressure oscillations in the unanesthetized rat.

Spectral analysis of cardiovascular signals has been extensively used to investigate circulatory homeostatic mechanisms. However, the nature of very low-frequency (VLF) fluctuations remains unclear. Because we previously observed enhanced VLF fluctuations in blood pressure (BP) in the sympathectomized rat (a model characterized by markedly increased plasma epinephrine levels), the aims of our study were to assess whether the genesis of VLF fluctuations in BP depends on circulating catecholamines and to determine which adrenergic receptor(s) and which membrane ion channel(s) are involved. We used continuous intra-arterial BP recordings from unanesthetized unrestrained rats to compute the power of VLF fluctuations in BP in the intact condition, during acute ganglionic blockade with hexamethonium, and after restoration of BP levels by infusion (in addition to hexamethonium) of adrenergic agonists (epinephrine, norepinephrine, and clonidine) or nonadrenergic vasoconstrictors (vasopressin). Effects of infusion of specific adrenergic receptor blockers (propranolol, prazosin, and yohimbine) with hexamethonium and catecholamines and infusion of various membrane ion channel blockers on VLF fluctuations in BP were also evaluated. Our results are as follows. 1) Ganglionic blockade drastically reduced BP levels and VLF fluctuations. 2) All vasoconstrictors restored BP levels, but only adrenergic vasoconstrictors generated striking VLF fluctuations in BP. 3) Catecholamine-induced fluctuations were abolished by alpha2-, but not alpha1- or beta-, adrenergic receptor blockade and by Ba2+-sensitive K+ channel or L-type Ca2+ channel, but not by other ion channel, blockers. We conclude that, in the conscious, unrestrained ganglion-blocked rat, catecholamine infusion generates VLF fluctuations in BP through stimulation of alpha2-receptors and activation of Ba2+-sensitive K+ channels. These fluctuations may have (patho)physiological relevance under conditions of disrupted circulatory homeostasis.