Effects on congestion, natriuretic peptides, diuretic efficiency, and renal function during different dose and administration of intravenous loop diuretic: preliminary data of DIUR-AHF Trial

Background

Although loop diuretic is the cornerstone of treatment in acute heart failure (AHF) there is no consensus about the best modality and amount to be used during acute phase. Current Guidelines do not provide specific insights regarding timing course and target dose. Usually physicians double the oral domestic amount when they start intravenous infusion, but a precise algorithm does not exist.

Aims

To compare admission and pre discharge clinical congestion and BNP trend in relation to furosemide amount and modality administration; 2- to evaluate diuretic efficiency and renal function in the four arms and the potential effects on outcome.

Methods

This is a multicentre prospective Trial (DIUR-AHF) designed in order to clarify the correct loop diuretic target avoiding potential side effects. The study enrolled patients with AHF BNP level >100 pg/ml and congestion signs. Patients were divided in four arms in accordance with modality administration: Continuous (Ci) vs Bolus (Bi) and dose administered Low (LD) vs High (HD) considering a cutoff 125 mg/die. All patients executed a clinical congestion evaluation and Chest radiography at admission and pre discharge, BNP sample and renal function were measured during the first 12 hours and before discharge. Diuretic efficiency (DE) defined as weight change per 40 mg of furosemide during infusional period. DE was estimated as the net fluid output produced per 40 mg of furosemide equivalents, Follow up were obtained by direct visit or phone contact at 30 and 60 days after discharge

Results

We included 268 hospitalized patients with a mean BNP level 987±440 pg /ml, mean congestion score (3.5±2) creatinine and GFR value were 1.6±0.7 mg/dl; and 48±20 ml/min/m2 respectively. At admission BNP and Creatinine were modestly increased in HD (P<0.01) compared with all other groups. Pre discharge Congestion score were increased in Bi and HD groups (2.5±1 vs 1±1), similarly BNP levels were increased in Bi and HD with respect to Ci and LD (454±215 and 413±223 vs 288±170 and 312±248 p<0.05). Whereas DE were significantly increased in Ci compared with the other arms (−1.23 vs −0.55 p<0.01). In all groups, low DE, residual congestion and BNP reduction <30% resulted in escalation of diuretic strategies and impaired outcome (HR 1.88 [1.16–204]; 2.1 [1.4–2.8]; 1.3 [0.88–2.1]). A significant correlation between poor DE and residual congestion was recruited (r=0.76). Worsening Renal function (WRF) occurred much more in HD and Ci compared to LD and Bi (HD 44%, Ci 35% vs LD 33% and Bi 23% p<0.01) without significant effects on outcome.

Conclusions

HD and Bi of furosemide are both related with reduced congestion and invreased BNP level before discharge. In all groups low DE residual congestion and poor BNP reduction appear associated with higher rate of adverse events. Current data provide additional features for AHF patients during intravenous loop diuretic administration

Funding Acknowledgement

Type of funding source: None

Multiple hormonal and metabolic deficiency syndrome in chronic heart failure: rationale, design, and demographic characteristics of the T.O.S.CA. Registry

Recent evidence supports the concept that progression of chronic heart failure (CHF) depends upon an imbalance of catabolic forces over the anabolic drive. In this regard, multiple hormonal deficiency syndrome (MHDS) significantly has impacts upon CHF progression, and is associated with a worse clinical status and increased mortality. The T.O.S.CA. (Trattamento Ormonale nello Scompenso CArdiaco; Hormone Therapy in Heart Failure) Registry (clinicaltrial.gov = NCT02335801) tests the hypothesis that anabolic deficiencies reduce survival in a large population of mild-to-moderate CHF patients. The T.O.S.CA. Registry is a prospective multicenter observational study coordinated by "Federico II" University of Naples, and involves 19 centers situated throughout Italy. Thyroid hormones, insulin-like growth factor-1, total testosterone, dehydroepiandrosterone , and insulin are measured at baseline and every year for a patient-average follow-up of 3 years. Subjects with CHF are divided into two groups: patients with one or no anabolic deficiency, and patients with two or more anabolic deficiencies at baseline. The primary endpoint is the composite of all-cause mortality and cardiovascular hospitalization. Secondary endpoints include the composite of all-cause mortality and hospitalization, the composite of cardiovascular mortality and cardiovascular hospitalization, and change of VO₂ peak. Patient enrollment started in April 2013, and was completed in July 2017. Demographics and main clinical characteristics of enrolled patients are provided in this article. Detailed cross-sectional results will be available in late 2018. The T.O.S.CA. Registry represents the most robust prospective observational trial on MHDS in the field of CHF. The study findings will advance our knowledge with regard to the intimate mechanisms of CHF progression and hopefully pave the way for future randomized clinical trials of single or multiple hormonal replacement therapies in CHF.

A Preliminary internet survey of pet rabbit owners’ characteristics

<p>This study aimed to conduct a preliminary survey to investigate basic ownership factors, frequency of microchipping and insurance and views of pet rabbit owners  n these areas and general rabbit management. More specifically, we aimed to investigate whether owners possess insurance, whether their rabbits are microchipped, and owners’ views on the recommendations relating to rabbits (e.g. recommended enclosure sizes) and the law. A questionnaire was designed and promulgated through social media sites and rabbit forums. A total of 1183 responses were received. Just over 29% of respondents sourced their rabbits through rescue centres. 73.9% (867/1174) of owners stated that they had no pet insurance for their rabbits. Concerning microchips, 78.3% (919/1173) of rabbits were not microchipped, while 21.7% (254/1173) were. This preliminary study found that the majority of individuals are of the opinion that the relevant law is insufficiently publicised. A more detailed study would be beneficial to investigate and provide further insight into rabbit owners and their views and concerns for rabbits. The results of such a study could help formulate rabbit-related information and guidelines which in turn could have a direct impact on pet rabbit welfare.</p>

Productive performance and histological features of intestinal mucosa of broiler chickens fed different dietary protein levels

To evaluate the effect of decreasing dietary protein on growth performance, carcass traits, and intestinal mucosal morphometry, 180 female Hubbard strain broiler chickens were divided into 3 groups and fed 3 isoenergetic diets ad libitum from 14 d of age until slaughter age (49 d). The treatments varied according to 3 protein levels: high-protein diet (HiP, 22.5% CP, DM basis), medium-protein diet (MedP, 20.5% CP), and low-protein diet (LowP, 18.5%). Diets were obtained by replacing wheat middlings with soybean meal and were formulated to meet or exceed broiler amino acid requirements of the NRC. Morphometric indices of duodenum, jejunum, and ileum were measured at the end of the feeding period and included villus height, crypt depth, villus-to-crypt ratio, and apparent villus surface area. The dietary protein level had a significant effect on final BW of birds, whereas ADG, ADFI, and feed efficiency remained unaffected by dietary treatment. The muscle (breast and drumstick) yields were significantly higher in birds fed the HiP diet compared with those of the MedP and LowP diets. Meat quality traits were not affected by the protein level. The villus surface area of all intestinal segments did not change among groups. Instead, reducing the dietary protein level to 20.5% resulted in a higher villus height and villus height to crypt depth ratio in the duodenum and ileum. On the basis of our findings, even if the high-protein diet promoted meat yield, a medium-protein diet could positively support broiler growth performance, as confirmed by favorable morphometric features of the intestine.

Canine leishmaniosis and euthanasia in Italy: a critical legal-ethical analysis

The increasing awareness that control of zoonotic visceral leishmaniosis (ZVL) depends on effective control of canine leishmaniosis has promoted research into leishmanial infection in dogs, but has also encouraged the indiscriminate elimination of seropositive dogs. Public health campaigns in various parts of the world (e.g. in Brazil and China) are designed to reduce the incidence of human ZVL by targeting/killing dogs. However, not all situations are the same; in Italy, for example, there would be little support for this type of control measure because attitudes towards animals are different. Moreover, research has suggested that the destruction of seropositive dogs is a relatively ineffective control measure. In this context, the authors reflect on some epidemiological, ethical and juridical aspects, aiming to contribute to the discussion and to find more feasible solutions.

Apoptosis of gut-associated lymphoid tissue in rainbow trout Oncorhynchus mykiss after incubation with Candida albicans and bacterial lipopolysaccharide

Until now a few studies have been carried out on the gut lymphoid system in fish despite its protective role in the host. Here, we have evaluated the effects of Candida albicans (Ca) and lipopolysaccaride (LPS) on the pyloric and terminal segments of gut in the rainbow trout Oncorhynchus mykiss. In particular, data show that both Ca and LPS are able to cause apoptosis of intestinal lymphoid cells as detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) procedure. These findings suggest a further modality of gut response in fish to environmental antigens.

Histological, histochemical and morphometric changes of splenic melanomacrophage centers (SMMCs) in Sparicotyle-infected cultured sea breams (Sparus aurata)

Diseases caused by parasites are much more frequently described in cultured fish, which suffer from artificial conditions and numerous stress factors. This study investigates the histological, histochemical and morphometric modifications of splenic melanomacrophage centers (SMMCs) infected by Sparicotyle chrisophrii (Monogenea, ectoparasite of the gills) in sea breams (Sparus aurata), cultured in floating cages in the Gulf of Gaeta (Italy). Infected fish swam near the water surface, showing severe signs of anemia. Several spleens were collected from both healthy and dead fish (70-100 gr. body weight). A spleen histopathology was evaluated by using traditional stainings, such as Haematoxylin and Eosin (HE), Periodic Acid-Schiff reaction (PAS), Perl's reaction for haemosiderin and Schmorl's reaction for lipofuscins. Furthermore, SMMCs morphometry was performed on PAS-stained sections to study 7 morphometric parameters [Mean SMMCs profile area (MPA), Mean SMMCs maximum diameter (Media), Mean SMMCs minimum diameter (media), Mean SMMCs diameter (Dia), Mean SMMCs Perimeter (P), Mean SMMCs Form Factor (FF) and Mean SMMCs number per square millimeter of spleen tissue (MN)]. A light microscope of HE stained sections of spleen revealed a dramatic increase in the size and number of SMMCs in parasitized animals. Morphometric data illustrated statistically significant differences (p < 0.01) of all studied parameters between healthy and diseased fish. This study emphasizes the importance of using histopathological investigations to unravel the complex biological host/parasite interaction, which results in systemic lesions affecting reared marine species.

Importation of mycobacteriosis with ornamental fish: Medico-legal implications

Mycobacterium fortuitum, as well as Mycobacterium marinum and Mycobacterium chelonae, are the etiological agents of fish Mycobacterioses. Mycobacteriosis has been reported to affect a wide range of freshwater and marine fish species, suggesting an ubiquitous distribution, and can cause zoonotic infections (known as "fish tank granuloma" or "swimming pool granuloma") in humans exposed to fish and contaminated water. Infection in human consists of nodular cutaneous lesions that can progress to tenosynovitis, arthritis, and osteomyelitis, depending on the immunological status. Authors describe some cases observed during routinary diagnostic activity in aquarium fish. Fish were sampled and histopathological, microbiological, and biomolecular exams were carried out. Histopathology showed systemic granulomatosis. Microbiological and biomolecular exams allowed us to identify the M. fortuitum as a main species. Finally, some considerations on the legal aspects of such disease are discussed.

Medico-legal considerations of canine leishmaniosis in Italy: an overview of an emerging disease with reference to the buying and selling of dogs

Leishmaniosis is a common infection in the canine population. Domestic dogs are the main reservoir hosts for zoonotic human visceral leishmaniosis in both the Old and New Worlds. In fact, canine leishmaniosis is not just a veterinary problem. In the light of some recent advances in the field of diagnosis, the author evaluated the medico-legal aspects of buying and selling dogs that are potentially affected by leishmaniosis. This paper clarifies why it is impossible to attribute redhibitory vice (an essential defect in a product which renders it useless or so diminishes its usefulness or value that it must be presumed that, if he had been aware of it, the buyer would not have bought it, or would have paid a lesser price) to this disease and highlights the necessity to improve Sicilian regional law no. 15 of 3 July 2000 concerning the creation of a dog register by giving every animal a health book. With this aim in mind, the author suggests that leishmaniosis be included in the list of notifiable diseases that appears in article 1 of the Italian Veterinary Police Regulations so as to reduce the possibilities of fraudulent trade in dogs known to be infected before purchase.

The veterinary surgeon in natural disasters: Italian legislation in force

Law No. 225/1992 established a National Service of Civil Protection, with the important role of 'safeguarding life, goods, settlements and the environment from damage deriving from natural disasters, catastrophes and calamities' (art. 1). This law arranges civil protection as a co-ordinated system of responsibilities administrated by the state, local and public authorities, the world of science, charitable organisations, the professional orders and other institutions, and the private sector (art. 6). The President of the Republic's Decree No. 66/1981 'Regulation for the application of Law No. 996/1970, containing norms for relief and assistance to populations hit by natural disasters--Civil Protection' mentions veterinary surgeons among the people that are called upon to intervene. In fact, in natural disasters the intervention of the veterinary surgeon is of great importance. The authors examine these laws and other legislation relating to the National Service of Civil Protection.

Low-dose dobutamine responsiveness in idiopathic dilated cardiomyopathy: relation to exercise capacity and clinical outcome

AIMS

To evaluate myocardial contractile reserve using low-dose dobutamine echocardiography in patients with chronic heart failure secondary to idiopathic dilated cardiomyopathy stratified by peak exercise oxygen consumption (VO(2)).

METHODS AND RESULTS

Sixty clinically stable patients (56+/-11 years; 45 males) with idiopathic cardiomyopathy and NYHA class I to III symptoms of heart failure were studied and followed-up for 13+/-3 months. All patients underwent cardiopulmonary exercise testing and low-dose dobutamine. The dobutamine infusion protocol consisted of an initial dose of 2.5 micro. kg(-1)per 3 min, increasing by 2.5 micro. kg(-1)per min every 3 min; the maximal dose was 10 micro. kg(-1)per min. The end-systolic volume index, left ventricular ejection fraction and cardiac output were measured at baseline and peak dobutamine dose and their change calculated as ((peak dose value-baseline value)/baseline value]x100. Ten normal subjects with normal left ventricular function and no coronary artery lesions served as a control group to compare low-dose dobutamine results. All analysed echocardiographic variables either at baseline or following dobutamine infusion were significantly lower in patients with chronic heart failure as a whole compared to the control group. When the patients were grouped according to Weber's classification, a statistically significant decrease in percentange changes in end-systolic volume index (rho=-0.77;P<0.0001), left ventricular ejection fraction (rho=-0.72;P<0.0001) and cardiac output (rho=-0. 82;P<0.0001) from class A to class C was observed. The mean percentage decrease in end-systolic volume index following the dobutamine infusion was 28.7+/-9% in class A (peak VO(2)>20 ml. kg(-1). min(-1)), 18.6+/-8% in class B (peak VO(2)between 16 and 20 ml. kg. min(-1)), and only 6.4+/-6% in class C (peak VO(2)between 10 and 16 ml. kg(-1). min(-1)) patient groups. At multivariate analysis, only the percentage change in end-systolic volume index was significantly associated with a peak VO(2)<15 ml. kg(-1). min(-1)(P=0.006). During the follow-up, 17 patients had events (15 readmissions for worsening heart failure and two deaths). At multivariate analysis, only the percentage change in end-systolic volume index was significantly associated with the occurrence of events (P=0.003). The area under the receiver operating characteristic curve for percentage change in end-systolic volume index was not significantly different from that for peak VO(2)(0. 86+/-0.04 vs 0.80+/-0.06;P:ns).

CONCLUSION

This study indicates that in patients with chronic heart failure secondary to idiopathic cardiomyopathy, the cardiac response to low-dose dobutamine, as assessed by echocardiography, is correlated with peak VO(2), an objective and accurate measure of the severity of the disease and clinical outcome.

Diastolic dysfunction and baroreflex sensitivity in hypertension

The determinants of diastolic dysfunction in patients with systemic hypertension are not completely known. To evaluate the possible role of age, arterial blood pressure, and baroreflex heart rate response impairment in causing diastolic dysfunction, we studied 61 patients (42 male; mean+/-SD age, 43.9+/-12 years) with newly recognized and therefore previously untreated systemic hypertension. Diastolic dysfunction was evaluated by means of Doppler echocardiography (and diagnosed as such when the early to atrial peak velocity ratio corrected to heart rate was <1), arterial blood pressure by 24-hour ambulatory monitoring, and baroreflex heart rate response by means of the spectral technique (alpha index) during paced (0.27 Hz) and spontaneous breathing (in a supine position and during tilt). Nineteen patients had diastolic dysfunction, the most powerful predictor of which was age (r=-0.63, P<0.001). The patients with diastolic dysfunction had significantly lower values for spectral baroreflex gain in the high-frequency band than those without (5.2+/-3 versus 8.4+/-5 ms/mm Hg during paced breathing, P<0.05; 7. 4+/-4 versus 13.3+/-7 ms/mm Hg in a supine position, P<0.05; 4.3+/-4 versus 5+/-2 ms/mm Hg during tilt, P<NS). Ambulatory blood pressure values were not significantly different in the patients with (137+/-14 and 89+/-9 mm Hg) and without (144+/-11 and 82+/-24 mm Hg) diastolic dysfunction. In conclusion, age and impaired baroreflex heart rate response (but not pressure overload) are determinants of left ventricular diastolic dysfunction in patients with newly recognized and untreated systemic hypertension.

Beta-blocker effects on respiratory sinus arrhythmia and baroreflex gain in normal subjects

STUDY OBJECTIVE

The results of studies on the effect of beta-adrenergic blockade on respiratory sinus arrhythmia (RSA) are discordant. The aim of this study was to verify whether chronic beta-adrenergic blockade is capable of increasing RSA, and therefore vagal outflow, and to analyze whether the mechanism of action is central or peripheral.

PARTICIPANTS AND DESIGN

Twenty normal subjects (28+/-2 years old) were randomized to receive a hydrophilic (nadolol) beta-blocker, a lipophilic (metoprolol) beta-blocker, and placebo.

MEASUREMENTS

After 1 week of therapy, a spectral analysis was made of the variability in heart rate and systolic BP during controlled breathing at 16 breaths/min. The high-frequency component was calculated for the RR interval (measure of RSA) and systolic pressure, and the squared coherence and phase functions were assessed between RR and systolic pressure fluctuations in the respiratory band; a negative phase means that RR changes follow systolic pressure changes. The gain in the relationship between the two signal fluctuations was also calculated.

RESULTS

Both beta-blockers increased the mean (+/-SD) RR interval (placebo=808+/-21, nadolol=1,054+/-30, metoprolol=1,031+/-27 ms; p<0.0001), RSA (placebo=542, nadolol=1,177, metoprolol=1,316 ms2; p=0.002), and the gain (placebo=13.6+/-1.5, nadolol=21.9+/-2.8, metoprolol=24.5+/-3.6 ms/mm Hg; p<0.002), and both modified the phase function (placebo=-21.1+/-5.3, nadolol=-1.8+/-4.9, metoprolol=-2.9+/-4.2 degree; p<0.0001). No difference was found between nadolol and metoprolol.

CONCLUSIONS

Chronic beta-adrenergic blockade enhanced both RSA and baroreflex gain and reduced the phase between the RR interval and systolic pressure oscillations. Since no difference was found between the hydrophilic and the lipophilic beta-blockers, these changes seem to be due to a peripheral effect.

Different trends of changes in heart rate variability in patients with anterior and inferior acute myocardial infarction

Modifications in heart rate variability (HRV) parameters occur after acute myocardial infarction. The aim of this study was to evaluate the trend of HRV change during the acute phase and the first month after myocardial infarction, and establish whether they were affected by the anterior or inferior location of the infarction. The time-domain HRV measures of 59 patients with a first uncomplicated acute myocardial infarction were computed from 24-hour ECG recordings made on days 1, 2, 10, and 28 after hospital admission. At day 1, the mean RR cycle length (NN), the standard deviation of the NN intervals (SDNN), and the root mean square successive difference of NN intervals (RMSSD) were lower in the patients with anterior myocardial infarction. Although the parameters were similar in all of the patients at day 28, their behavior over time was different (P = 0.01): the SDNN in the patients with inferior myocardial infarction had decreased to the values found in anterior myocardial infarction patients by day 2 but, at day 10, both NN and SDNN tended to recover in both groups; RMSSD had diminished in both groups by day 2, but at day 10, had increased in the patients with anterior, but not in those with inferior myocardial infarction. These findings suggest that (1) in the very early phase of myocardial infarction, HRV is different in the two locations, (2) during the first hours of myocardial infarction patients with inferior location showed a greater vagal activity than patients with anterior location that became lower at day 10, and (3) the recovery of HRV is an early phenomenon in both groups, being already evident by the second week after myocardial infarction.

Effect of respiratory rate on the relationships between RR interval and systolic blood pressure fluctuations: a frequency-dependent phenomenon

OBJECTIVE

The aims of this study were to determine the relationships between oscillations in systolic blood pressure and heart period at different breathing frequencies and to investigate the role of sympathetic contribution to this relationship.

METHODS

Fourteen healthy volunteers underwent three randomized periods of controlled breathing at 6, 10 and 16 breaths/min. ECG (RR), respiratory signal (RESP) and systolic blood pressure (SBP) were continuously recorded. The component of RR and SBP oscillations related to respiration (RRResp and SBPResp) was defined by means of uni- and bivariate spectral analysis. The squared coherence (K2) and phase between RR and RESP, and RR and SBP (RR-SBP) were also assessed. When the K2 of RR-SBP in the respiratory band was > 0.5, we considered the phase and calculated the closed-loop gain between the two signals. Seven subjects were also studied after chronic metoprolol treatment.

RESULTS

Although the mean values of RR and SBP did not differ between the three periods of breathing, the higher the respiratory rate, the smaller the RRResp and SBPResp. The phase was always negative (SBPResp changes preceded RRResp changes), thus suggesting a baroreflex link. The higher the respiratory rate, the lower the gain and phase. Pharmacological beta-adrenoceptor blockade increased the gain and shifted the phase, but the relationships found at baseline between the respiratory rate and both the gain and phase remained unchanged.

CONCLUSIONS

The effect of breath rate on the relationship between heart rate and systolic pressure variabilities is a frequency-dependent phenomenon that is also independent of the sympathetic drive.

Comparison between noninvasive indices of baroreceptor sensitivity and the phenylephrine method in post-myocardial infarction patients

BACKGROUND

Depressed baroreflex sensitivity obtained by means of a phenylephrine test plays a prognostic role in patients with a previous myocardial infarction. Our purpose was to evaluate the correlation and agreement between the baroreflex sensitivity obtained with phenylephrine and that obtained by two noninvasive methods: the alpha-index and sequence analysis.

METHODS AND RESULTS

The alpha-index was measured by means of the spectral analysis of RR and systolic blood pressure variabilities in both the high- and low-frequency bands; sequences were identified from simultaneously recorded time series in which the RR and systolic blood pressure concurrently increased or decreased. Noninvasive baroreflex sensitivity tests were performed during both spontaneous and controlled respiration. Fifty-two consecutive patients with recent myocardial infarction underwent the analyses. Although the correlations between phenylephrine and either of the noninvasive methods were always significant, those found during controlled respiration had the highest r values (r=.70). However, the limits of agreement calculated by means of the Bland and Altman method were wide for both noninvasive methods.

CONCLUSIONS

The results obtained by means of noninvasive baroreflex sensitivity assessments should not be used in clinical practice as an alternative to those obtained by the phenylephrine method.

Percent achieved of predicted peak exercise oxygen uptake and kinetics of recovery of oxygen uptake after exercise for risk stratification in chronic heart failure

To investigate whether percent achieved of predicted peak exercise oxygen uptake (%VO2max) and recovery of oxygen consumption after exercise may provide prognostic information in chronic heart failure (CHF), we prospectively studied 196 patients with mild to moderate CHF. The following variables were examined: age, etiology of CHF, functional class, ejection fraction (EF), peak exercise oxygen uptake normalized for body weight (VO2max), %VO2max, time to reach 50% of the peak oxygen uptake after exercise (T1/2VO2max), presence of nonsustained ventricular tachycardia (NSVT) and inability to take ACE-inhibitors. VO2max was the most powerful predictor of cardiac death (P<0.0001). Other independent predictors of death were EF, T1/2VO2max, NSVT and inability to take ACE-inhibitors. The discriminatory accuracy of VO2max for cardiac death was not significantly greater than that of %VO2max. In conclusion, the determination of %VO2max does not enhance risk stratification in CHF whereas the kinetics of oxygen consumption after exercise can provide prognostic information.

Assessment of cardiac vagal activity in patients with hyperthyroidism

Previous studies suggested that in patients with hyperthyroidism an autonomic imbalance and in particular a lower than normal vagal activity might be present. To verify this hypothesis we have evaluated the respiratory sinus arrhythmia (RSA, a measure of cardiac vagal activity) in ten hyperthyroid patients and in ten normal subjects. RSA was calculated from the power of the spectral component of the heart rate variability in high frequency band (HF-RR) during both spontaneous (supine and passive head-up tilt) and controlled breathing (supine). During controlled breathing the phase relation between heart rate and respiratory has been computed. The hyperthyroid patients showed a higher heart rate in all three conditions (P<0.001) and higher spontaneous respiratory rate in supine position (centered frequency of HF-RR: 0.342+/-0.015 vs 0.262+/-0.016 Hz; P<0.001). No difference was found in hyperthyroid patients compared to controls in terms of the HF-RR power in normalized units both during spontaneous breathing (supine, 43+/-8.3 vs 39.7+/-6.7%; tilt 18.8+/-5.9 vs 19.3 vs 4.1%; mean+/-SE) and controlled breathing (45.4+/-7.1 vs 48.9+/-6.9%). No difference was found also in terms of the phase relationship between the heart rate and the respiratory signals (77.5+/-32.3 vs 77.5+/-28.1, degrees). Hyperthyroid patients seem not to have an impaired cardiac vagal activity.

Effects of hydrophilic and lipophilic beta-blockers on heart rate variability and baroreflex sensitivity in normal subjects

To evaluate the effect of a hydrophilic and a lipophilic beta-blocker on the autonomic nervous system, 20 normal subjects were studied under baseline conditions and 7 days after being randomly assigned to metoprolol (200 mg/day), nadolol (80 mg/day), and placebo. Under each condition, the time-domain parameters were analyzed by means of 24-hour ECG monitoring and the frequency-domain parameters by means of the autoregressive method using 10-minute ECGs during rest, controlled respiration, and after a head-up tilt test. The alpha index (the gain in the relationship between the RR period and systolic arterial pressure variability) was also calculated. Both nadolol and metoprolol significantly increased all of the time-domain parameters except the standard deviation of the RH intervals; they also modified the frequency-domain parameters. Both blunted the significant reduction in the high frequency (HF) component and alpha index during tilt. In normal subjects, hydrophilic and lipophilic beta-blockers similarly modify the time- and frequency-domain parameters that are particularly evident when high sympathetic tone is present (during daytime and tilt). The value of the alpha index was increased by both beta-blockers in the HF, but not in the low frequency band; this difference might be due to the fact that the former is a measure of the vagal component of the baroreflex control and the latter a measure of the sympathetic component. The effects of hydrophilic and lipophilic beta-blockers on the time- and frequency-domain parameters of heart rate variability are similar.

Heart rate dependency of premature ventricular contractions. Correlation between electrocardiographic monitoring and exercise-related patterns

AIMS

The identification of the response of ventricular arrhythmias to exercise testing could provide important information in the clinical setting but is difficult to obtain as no definite criteria are available. The aim of this study was to evaluate whether analysis of spontaneous heart rate dependency of premature ventricular contractions evaluated by means of 24 h electrocardiographic monitoring is capable of predicting their behaviour during exercise.

METHODS AND RESULTS

One hundred and twenty-six patients (49 +/- 16 years) with frequent (> 30 h) premature ventricular contractions underwent 24 h electrocardiographic monitoring in order to evaluate the relationship between arrhythmias and heart rate, and an exercise test in order to evaluate the behaviour of the arrhythmias. On the basis of the incidence of premature ventricular contractions at different cardiac cycle lengths found at electrocardiographic monitoring, three groups of patients were identified: 34 with a tachycardia-enhanced pattern (the shorter the cycle length the higher the incidence of arrhythmias); 32 with a bradycardia-enhanced pattern (the longer the cycle length the higher the incidence of arrhythmias); and 60 patients with an indifferent pattern (no relationship). During the exercise test, the number of premature ventricular contractions/min at maximal effort in comparison with baseline increased in patients with a tachycardia-enhanced pattern (couplets or runs appeared in 10), decreased in those with a bradycardia-enhanced pattern and did not change in those with an indifferent pattern. The positive predictive accuracy of the tachycardia-enhanced pattern in predicting an increase in premature ventricular contractions > 100% at maximal effort was 78%.

CONCLUSION

Identification of spontaneous behaviour between the incidence of premature ventricular contractions and the length of the preceding cardiac cycle may predict the behaviour of arrhythmias during exercise.

[Value of peak oxygen consumption during exercise for the prognostic stratification of patients with severe systolic dysfunction of the left ventricle]

We sought to assess the prognostic value of peak exercise oxygen consumption (peak VO2) in patients with severe left ventricular systolic dysfunction and mild to moderate symptoms of chronic heart failure. We focused on 1-year mortality. We prospectively studied 77 patients with left ventricular ejection fraction (EF) < or = 25% and NYHA functional class I/II (61%) or III (39%). All patients underwent cardiopulmonary exercise test, two-dimensional echocardiography and 24-hour Holter monitoring. Examined variables were age, etiology, NYHA functional class, EF, peak VO2, and presence of nonsustained ventricular tachycardia. Overall 1-year mortality rate was 23%. At univariate analysis, age > or = 60 years, ischemic etiology, and peak VO2 < 14 ml/kg/min were significantly associated with mortality. At multivariate analysis, peak VO2 was the most powerful predictor of death (p = 0.0001). In the subgroup of patients with a peak VO2 < 14 ml/kg/min, the actuarial 1-year mortality rate was 56%. One additional patient underwent heart transplantation because of severe hemodynamic deterioration. By contrast, in the subgroup of patient with a peak VO2 > 14 ml/kg/min, 1-year mortality rate was 11%. This study provides evidence that patients with severe left ventricular dysfunction and mild to moderate symptoms of chronic heart failure can be accurately stratified into subgroups with strikingly divergent prognosis by an objective criteria such as peak VO2.

[The effects of chronic beta-blocker administration on respiratory sinus arrhythmia]

The results of studies on the effect of beta-adrenergic blockade on respiratory sinus arrhythmia (RSA) are discordant. In some studies in which an increased RSA was reported, central vagotonic activity has been proposed. The aim of this study was to verify whether chronic beta-adrenergic blockade is capable of increasing RSA, and therefore vagal outflow, and to analyze whether the mechanism of action is central or peripheral. Twenty normal subjects (mean age 28 +/- 2 years) were randomized to receive a hydrophilic (nadolol, N), a lipophilic (metoprolol, M) beta-blocker and placebo (PL). After 1 week of therapy a spectral analysis was made of the variability in heart rate and systolic blood pressure (SBP) while they controlled their breathing at 16 breaths/min for a period of 5 min. The high frequency component was calculated for the RR interval (HF-RR, RSA measure) and SBP (HF-SBP), and the squared coherence (K2) and phase functions (phi HF) were assessed between RR and SBP fluctuations in the respiratory band (RR-SBP); a negative phi HF means that RR changes follow SBP changes. The alpha HF (an index of the baroreflex gain) was also calculated. Both beta-blockers increased the mean RR interval (PL 808 +/- 21, N 1054 +/- 30, M 1031 +/- 27 ms; p < 0.0001), HF-RR (PL 6.3 +/- 0.3, N 7.1 +/- 0.3, M 7.2 +/- 0.3 ln-ms2; p = 0.002) and alpha HF (PL 13.6 +/- 1.5, N 21.9 +/- 2.8, M 24.5 +/- 3.6 ms/mmHg; p < 0.002), and both modified phi HF (PL -0.23 +/- 0.05, N -0.02 +/- 0.05, M -0.03 +/- 0.04 s; p < 0.0001). No difference was found between N and M. Chronic beta-adrenergic blockade enhanced RSA and baroreflex gain and reduced the phase between the RR interval and SBP oscillations. Since no difference was found between the hydrophilic and the lipophilic beta-blockers, these changes seem to be due to a peripheral effect.

Dependency of premature ventricular contractions on heart rate

To identify a method for characterizing the dynamic behavior of ventricular arrhythmias at different heart rates, 201 consecutive patients with frequent premature ventricular contractions (PVCs) underwent two 24-hour electrocardiographic monitoring periods. The percentage of PVCs for each cycle length was calculated and then analyzed by linear regression analysis. On the basis of the significance of the p value, and the positive or negative value of the slope, we identified three trends: a tachycardia-enhanced pattern (p < 0.01, slope negative), a bradycardia-enhanced pattern (p < 0.01, slope positive), and an indifferent pattern (p > 0.01). During the first monitoring period, a tachycardia-enhanced pattern was present in 56 patients (28%), a bradycardia-enhanced pattern was present in 49 patients (24%), and an indifferent pattern was present in 96 patients (48%). This relationship was reproducible in 41 of the patients with a tachycardia-enhanced pattern (73%), in 29 of the patients with a bradycardia-enhanced pattern (59%), and in 70 patients with an indifferent pattern (72%). In conclusion, it is possible to identify a spontaneous trend between the incidence of ventricular arrhythmias and the length of the preceding cardiac cycle that seems to remain stable over time.

Effects of nadolol and its combination with atrial pacing on rate-enhanced ventricular premature complexes

To explore the role of heart rate in the genesis of ventricular premature complexes whose incidence increases when the length of the preceding cardiac cycle decreases, we analyzed the effect of nadolol alone and together with atrial pacing in 4 patients. Nadolol lengthened the RR cycle and suppressed ventricular premature complexes; atrial pacing, restoring the baseline RR cycle lengths, led to the reappearance of ventricular premature complexes, suggesting the major role of heart rate.

Short- and long-term reproducibility of time and frequency domain heart rate variability measurements in normal subjects

OBJECTIVE

To obtain data relating to the reproducibility of the time and frequency domain measurements obtained from 10-min ECG recordings.

METHODS

Eighteen normal volunteers underwent evaluations of time and frequency domain heart rate variability 2 weeks and 7 months after baseline analysis. The time domain parameters were mean NN, the standard deviation of NN intervals, the percentage of successive NN intervals > 50 ms and the root mean square successive difference of NN intervals. The frequency domain evaluations (total power, low frequency, and high frequency) were made by means of both the Fast Fourier Transform algorithm (FFT) and the autoregressive method (AR) from 10-min ECG recordings made under three different conditions: rest, controlled respiration, and after a passive head-up tilt test. Reproducibility was evaluated by means of the interclass correlation coefficient (ICC), comparing baseline values with the results obtained at the second week and the seventh month. Time domain evaluation were also made from 10-min ECG.

RESULTS

All of the time domain measurements had an ICC > or = 0.75, except for the standard deviation of NN intervals, which had an ICC of 0.57. The frequency domain parameters obtained by means of either FFT or AR showed similar reproducibility. Low frequency was reproducible under all three conditions, total power only at rest, and high frequency only during controlled respiration.

CONCLUSION

The reproducibility of frequency domain parameters depends on the analysed condition. These results are of primary importance when the effects of drugs or other interventions on heart rate variability are under investigation.

The effect of nadolol on heart rate and the standard deviation of the RR intervals

The aim of this study was to evaluate the effect of nadolol in modifying the standard deviation of RR intervals (SDRR) and the coefficient of variance (CV) in 47 patients characterized by symptomatic, frequent (> 30 h-1) and reproducible premature ventricular contractions (PVCs). Sixteen patients had suffered a previous myocardial infarction (Group 1), 22 had various non-ischaemic cardiac diseases (Group 2) and nine had no heart disease (Group 3). All patients underwent two 24 h Holter recordings during the washout period, and a third Holter recording was taken 5 days after the administration of nadolol (80 mg.day-1). The RR cycle length (RR), SDRR and CV were evaluated for each 24 h period, as well as for six daytime (1000-1600h) and six night-time hours (0000-0600h). In all three groups, nadolol was highly effective in lengthening RR. However, the effect on SDRR was different in the three groups; 24-h SDRR tended to be reduced in all three groups (but the reduction was significant only in Group 1) due to a certain RR homogeneity. On the other hand, daytime SDRR tended to increase (but the increase was significant only in Group 3). CV is concomitantly affected by heart rate and SDRR, therefore it may be more sensitive in evaluating the effect of beta-blockers. The reduction in CV post-nadolol means that the bradycardia-induced effect is associated with an inadequate increase, or even a reduction in SDRR, whereas the absence of any CV changes (found only in Group 3) is the result of a concomitant increase in both RR cycle length and SDRR.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of the autonomic nervous system in the acute phase of myocardial infarction]

The aim of this study was to evaluate how heart rate variability changes during acute myocardial infarction (AMI) and whether this change is different in anterior and inferior AMI. For this purpose 10 patients with anterior (mean age 53 +/- 11 years) and 11 patients with inferior (mean age 55 +/- 11 years) AMI underwent 2 consecutive 24-hour Holter recordings (H1, H2) which started, at most, 6 hours after the onset of symptoms and a further two H at the 10th (H3), and 28th day (H4) of AMI. None of the patients suffered from diabetes or was taking beta-blockers. The standard deviation of the RR intervals (SDRR) for a 24-hour period was evaluated for each H in the group of patients with anterior and inferior AMI. In H1, SDRR was statistically lower in anterior compared to inferior AMI (64 +/- 20 versus 106 +/- 27; p < 0.0001). No statistically significant differences were found in H2 between the anterior and inferior AMI (72 +/- 19 versus 76 +/- 14), due to a reduction in SDRR in inferior AMI: from 106 +/- 27 in H1 to 76 +/- 14 in H2; p < 0.002. No statistically significant changes were present in anterior AMI patients between H1 and H2 (64 +/- 20 versus 72 +/- 19). SDRR recovers at H3 increasing in both groups (anterior: 101 +/- 28, p < 0.001; inferior: 108 +/- 29, p < 0.004). No further significant changes in SDRR were present at H4 for either group (anterior 117 +/- 30; inferior: 118 +/- 31).(ABSTRACT TRUNCATED AT 250 WORDS)