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Biomedical subjects

L Tavazzi

Publications and source records attributed to L Tavazzi.

At least 91 records · Page 5Linked to original sources
PubMed1997

Abnormal awake respiratory patterns are common in chronic heart failure and may prevent evaluation of autonomic tone by measures of heart rate variability.

BACKGROUND: Reduced heart rate variability, particularly in the Very-low-frequency (VLF) spectral band, has been found to be a marker for poor prognosis in patients after myocardial infarction, but the origin of the VLF oscillations is unclear. In this study, we demonstrate that the power of cardiovascular oscillations in the VLF band in awake patients with mild to severe chronic heart failure is greatly increased by the common occurrence of unrecognized irregularity of breathing, which may confound the use of heart rate variability measures as indexes of autonomic tone or prognosis. METHODS AND RESULTS: Among 110 consecutive patients referred for consideration of transplantation, 90 were in sinus rhythm, of whom 10 were excluded as unstable. The remaining 80 patients underwent recordings of ECG, beat-to-beat arterial oxygen saturation (SaO2), and respiration during both spontaneous and controlled breathing. During spontaneous awake breathing, 64% showed periodic breathing or Cheyne-Stokes respiration (CSR), which was associated with dominant power in the VLF band of all signals. This VLF power accounted for 55%, 77%, and 87% of heart rate variability, respectively, in patients with normal breathing, periodic breathing, and CSR. It was reduced by 48% and 62%, respectively, during controlled breathing in patients with periodic breathing or CSR. Controlled ventilation also improved oxygen saturation and markedly reduced its variability. CONCLUSIONS: Breathing disorders are surprisingly common in awake patients with poor left ventricular function and produce large VLF oscillations in heart rate variability. If measures of heart rate variability are used for prognostic purposes during both short-term and long-term recordings, the confounding effects of variable respiratory patterns should be excluded. Respiratory rehabilitation might help control potentially hazardous surges in sympathetic tone.

Adult↗
PubMed1997

Loading manipulations improve the prognostic value of Doppler evaluation of mitral flow in patients with chronic heart failure.

BACKGROUND: Mitral flow velocity patterns (MFVPs) evaluated by Doppler echocardiography are strong predictors of survival in various cardiac diseases. However, MFVPs may change over time according to loading conditions. We performed this prospective study to assess whether changes in MFVP induced by loading manipulations provided additional prognostic information in 173 patients with chronic heart failure. METHODS AND RESULTS: Simultaneous Doppler echocardiographic and right-sided hemodynamic recordings were obtained at baseline in all patients, during nitroprusside infusion in the 98 patients who had a baseline restrictive (early-to-late flow velocity ratio > 1 and deceleration time < or = 130 ms) MFVP, and during passive leg lifting in the 75 patients who had a baseline nonrestrictive MFVP. Patients were categorized, according to changes in MFVP, into four groups: 61 patients with an irreversible restrictive, 37 with a reversible restrictive, 48 patients with a stable nonrestrictive, and 27 patients with an unstable nonrestrictive MFVP. Fifty patients experienced major cardiac events. Cox analysis revealed that MFVP was a strong predictor of events and that the response to loading manipulations improved its prognostic value. Patients with an irreversible restrictive MFVP had a higher event rate (51%) than patients with a reversible restrictive MFVP (19%). Among patients with a baseline nonrestrictive MFVP, those with a stable nonrestrictive MFVP had the lowest event rate (6%), whereas the event rate was 33% in patients with an unstable nonrestrictive MFVP. CONCLUSIONS: In patients with chronic heart failure, MFVPs provide independent prognostic information. Their prognostic value can be further increased by assessment of the changes induced in them by loading manipulations.

Adrenergic beta-Antagonists↗
PubMed1997

Dobutamine and nitroprusside infusion in patients with severe congestive heart failure: hemodynamic improvement by discordant effects on mitral regurgitation, left atrial function, and ventricular function.

OBJECTIVES: In patients with severe heart failure additional therapeutic support with intravenous inotropic or vasodilator drugs is frequently used in the attempt to obtain hemodynamic control. The nature and extent to which diastolic filling, atrial function, and mitral regurgitation are modified by these drugs have not been fully explored. The aim of this study was to compare the acute adaptations of the left ventricular performance, left atrial function, and mitral regurgitation that accompanied hemodynamic improvement during intravenous dobutamine and nitroprusside infusions in patients with severe chronic heart failure. METHODS: Forty consecutive patients with severe heart failure were evaluated by simultaneous echo-Doppler and hemodynamic investigations at baseline and during nitroprusside and dobutamine administration. Mitral flow velocity variables, left atrial and ventricular volumes, left atrial reservoir, conduit and pump volumes, and mitral regurgitation jet area were compared by analysis of variance for repeated measurements. RESULTS: Nitroprusside increased cardiac output (2.1 +/- .5 vs 2.6 +/- .5 L/min/m2, p < 0.004), reduced left ventricular filling pressure (25 +/- 6 vs 14 +/- 4 mm Hg, p < 0.0001), and improved left atrial pump volume (19 +/- 3 vs 26 +/- 12 ml, p < 0.02) without variations in left atrial reservoir and conduit volume. The restoration of preload reserve and improvement of the atrial contribution to left ventricular diastolic filling were demonstrated by the Doppler mitral flow pattern, which moved from a restrictive to a normal pattern. Furthermore mitral regurgitation decreased in all patients (9 +/- 4.6 vs 4.6 +/- 3.4 cm2, p < 0.0001). Dobutamine increased cardiac output (2.1 +/- .5 vs 2.8 +/- .6 L/min/m2), but the effects on pulmonary wedge pressure and mitral regurgitation were variable and unpredictable. Left atrial reservoir and conduit volumes increased, whereas left atrial pump volume did not change (19 +/- 13 vs 22 +/- 14 ml, p = NS). Furthermore Doppler mitral flow showed a persistent restrictive pattern. CONCLUSIONS: In patients with advanced congestive heart failure both nitroprusside and dobutamine improve cardiac output, with different adaptations of left ventricular performance and left atrial function. Nitroprusside seems to restore both atrial and ventricular pump function better. Careful echo-Doppler monitoring during drug infusion provides information relevant to the clinical treatment of individual patients.

Atrial Function, Left↗
PubMed1997

Depressed arterial baroreflex sensitivity and not reduced heart rate variability identifies patients with chronic heart failure and nonsustained ventricular tachycardia: the effect of high ventricular filling pressure.

In chronic heart failure (CHF) the contributing role of increased sympathetic activity and hemodynamic dysfunction in the genesis of ventricular arrhythmias has not been well established. To assess the relation between severe ventricular arrhythmias, hemodynamic impairment, and autonomic nervous system derangement, 142 patients with CHF in sinus rhythm underwent 24-hour electrocardiographic recording, right-sided heart catheterization, and evaluation of sympathovagal balance by heart rate variability (HRV) and baroreflex sensitivity (BRS). Patients were grouped according to the absence (without nonsustained ventricular tachycardia [NSVT]; n = 87) or presence (with NSVT; n = 55) of NSVT. Patients with NSVT had higher pulmonary artery and capillary pressures and more pronounced signs of sympathetic activation and parasympathetic withdrawal compared with those without NSVT. However, logistic regression analysis revealed that depressed BRS but not reduced HRV was significantly associated with the presence of NSVT, at both univariate analysis and after adjustment for clinical and hemodynamic variables. Moreover, it was found that when depressed BRS was associated with high pulmonary capillary pressure, the odds ratio for having NSVT rose markedly from 3.8 to 6.5. In conclusion, this study indicates that in stable CHF the assessment of arterial baroreflex function, but not HRV analysis, allows identification of patients at high risk of NSVT. It is suggested that the effect of depressed BRS is strengthened by the simultaneous presence of increased myocardial wall stress. These data support the hypothesis of a contributory role of autonomic nervous system dysfunction as expressed by the inability to activate effective vagal reflexes and an indirect index of ventricular stretch in the genesis of life-threatening arrhythmias.

Autonomic Nervous System↗
PubMed1997

Skeletal muscle function at low work level as a model for daily activities in patients with chronic heart failure.

AIM: Metabolic exercise abnormalities have been reported in chronic heart failure patients. This study sought to evaluate whether these abnormalities affected daily activity. METHODS AND RESULTS: In 16 patients with moderate-to-severe chronic heart failure and in eight controls we measured femoral flow (thermodilution) and metabolism (glucose, lactate, free fatty acids, blood gas values) at rest and during a constant load of 20 W, which may mimic a daily activity. At rest, chronic heart failure patients had a leg flow similar to controls, but showed a higher leg oxygen consumption (4.6 +/- 0.6 vs 2.6 +/- 0.4 ml.min-1; P < 0.05), a higher arteriovenous oxygen difference (7.2 +/- 0.5 vs 5.4 +/- 0.7 ml.dl-1; P < 0.05), and a lower femoral vein pH (7.37 +/- 5.03 vs 7.42 +/- 0.01; P = 0.01). At 20 W, chronic heart failure patients had a leg flow similar to controls, but showed increased lactate release (from resting 11.7 +/- 33 to 142 +/- 125 micrograms.min-1 P < 0.0001 vs controls, from resting 5.7 +/- 15.4 to 50 +/- 149 micrograms.min-1 ns), higher arterial concentration of free fatty acids (781 +/- 69 vs 481 +/- 85 mumol.l-1; P < 0.01), lower femoral vein HCO3 (24.1 +/- 2.6 vs 26.3 +/- 1.7 mmol.l-1; P < 0.05) and base excess (-2.3 +/- 2.3 vs -0.24 +/- 1.7 mmol.l-1; P = 0.01). CONCLUSION: In chronic heart failure patients, the important cellular metabolic alterations already present at rest partially affect daily activities, owing to a further decrease in the efficiency of muscle metabolic processes, and may preclude tolerance of heavier activities. Such alterations appear, at least in part, independent of peripheral haemodynamic responses to exercise.

Activities of Daily Living↗
PubMed1997

From clinical data records to research: a database system for the study of clinical and functional indicators of chronic heart failure.

The identification of reliable clinical and functional indicators of Chronic Heart Failure (CHF) is currently a major research challenge for physicians dealing with this pathology. With the aim of providing an adequate infrastructure for this research, we have developed a Database System where all relevant information concerning CHF patients during follow-up can be efficiently recorded, monitored, extracted and easily transferred to commercial packages for data processing and statistical analysis. Patient clinical status is recorded every 6 months, whereas data from several laboratory investigations are recorded every 12 months. All complications or events between two successive controls are recorded too. Patients needing cardiac transplantation are entered in a transplantation waiting list. The Database is fully integrated into the Hospital Information System and meets the standards of the national database of CHF patients. It grows with the concurrent activity of several independent teams, all of which have access to complete and structured information for research purposes. A user-friendly procedure allows the export in a standard format (Microsoft Excel) of all patients' data pertaining to a selected set of controls and variables of interest. These data are used directly for analysis or sub-selections are performed by the investigator through a simple query language. Depending on the objectives and complexity of the research, different commercial statistical analysis packages are available, which are used by clinical investigators autonomously or with the aid of a statistician. This overall approach allows great autonomy of each user in extracting, manipulating and statistically analyzing data. The Database has been in use at the Heart Failure Unit of our Rehabilitation Center since October 1992 and 595 patients have been enrolled since then. Several studies based on these data have been performed and more than 120 scientific communications and 30 articles in national and international journals have been produced. Hence, this experience represents a successful example of how clinical data records can be efficiently and effectively linked to valuable clinical research.

Aged↗
PubMed1997

Sleep disorders and breathing alterations in patients with chronic heart failure.

Cheyne-Stokes respiration can appear during sleep in patients with chronic heart failure and is generally attributed to a tendency to hyperventilate causing PCO2 to fall below the apnea threshold. We recorded sleep pattern and nocturnal arterial oxygen desaturation during Cheyne-Stokes respiration and correlated those with hemodynamic alterations, in order to investigate their possible role in the evolution of chronic heart failure. Sixty chronic heart failure patients, after optimization of therapy, underwent a polysomnographic study and hemodynamic and echocardiographic evaluations within a few days. The patients were then enrolled in the follow-up of our pre-transplantation program. Only slight alterations of sleep architecture were detected. During sleep, Cheyne-Stoke respiration was present in 50% and arterial oxygen desaturations in 54% of patients. An increased pulmonary wedge pressure (24.7 +/- 8.3 vs 16.7 +/- 8.9 mmHg, p < 0.000) was significantly correlated with the presence of nocturnal Cheyne-Stokes episodes, while cardiac index was not (1.9 +/- 0.6 vs 2.0 +/- 0.5 l m-2 min-1, p = 0.42). In a multivariate analysis of hemodynamic and polysomnographic data, mortality or heart transplantation in status 1 was predicted at the two year follow-up only by an increased pulmonary wedge pressure. In conclusion, in advanced chronic heart failure, with optimized therapy, nocturnal Cheyne-Stokes respiration is present in half of the cases, with concomitant falls in arterial oxygen desaturation. These events were not independently predictive of mortality. The strong correlation found between increased left ventricular filling pressure and presence of Cheyne Stokes respiration and the lack of correlation with cardiac index suggest that other hemodynamic mechanisms besides reduced cardiac output are responsible for this respiratory abnormality.

Cardiac Catheterization↗
PubMed1997

Age limits for heart transplantation: medical aspects.

OBJECTIVE: To contribute to the analysis of the medical issue of aging as a selection criteria for heart transplantation (HT) METHODS: Elderly candidates (52 subjects, aged > or = 60) were compared with younger patients (64 candidates, aged 50-55) in: clinical pattern (sex, etiology, duration of disease); laboratory and instrumental data (multiple organ function, hemodynamics, maximal and submaximal exercise capacity, nutritional status); follow-up (death, transplantation, status I, decompensation, complications) of at least 6 months. RESULTS: When compared with younger candidates, over 60 patients did not differ in clinical pattern, in all instrumental data, in end-organ function, in transplantation rate, in fatal and non-fatal cardiac events. In both groups the medical management was similarly complex. CONCLUSION: In regard to the medical issue, no reasons emerged to exclude older patients suitable from HT.

Aged↗
PubMed1997

[The psychological side of chronic heart failure. A pluriannual experience].

The present study summarizes the authors' experience reached in the last four years with chronic heart failure patients', particularly referring to the psychological aspects. The 218 male patients (age 51.7 +/- 8.3) psychological profile (obtained by means of the CBA 2.0 Primary Scales) has shown higher scores in the anxiety, depression and psychophysiological disorders scales and lower scores in some of the fear scales, compared with the reference normative group. The CBA 2.0 Schedule 4 has enlightened suicidal ideas, eating and sleep disorders, economic and sexual problems. The comparison between the psychological and the many cardiological variables taken into account, has not allowed to highlight significant relationships on the whole. Our data support the necessity to introduce other--likely subjective--variables in the studies aimed at analyzing the relationships between psychological and cardiological factors in the chronic heart failure patients.

Adult↗
PubMed1996

Assessment of right ventricular function in patients with congestive heart failure by echocardiographic automated boundary detection.

In patients with chronic heart failure, echocardiographic automated boundary detection (ABD) can reliably assess right ventricular function. The measurements obtained by ABD were highly reproducible, strongly correlated with radionuclide right ventricular ejection fraction, and superior to those obtained by conventional manual echocardiographic methods.

Electrocardiography↗
PubMed1996

Comparison of Doppler echocardiography with thermodilution for assessing cardiac output in advanced congestive heart failure.

Noninvasive cardiac output estimation by Doppler echocardiography was compared with thermodilution and Fick oxygen methods in 73 patients with advanced chronic congestive heart failure due to dilated cardiomyopathy. In these patients, Doppler echocardiographic measurements showed a closer agreement with Fick measurements than that of thermodilution.

Cardiac Output↗
PubMed1996

Concomitant factors of decompensation in chronic heart failure.

The concomitant factors implicated in 328 nonfatal decompensations of 304 patients with congestive heart failure were: arrhythmias in 24%, infections in 23%, poor compliance in 15%, angina in 14%, iatrogenic factors in 10%, and other causes in 5% of cases. New York Heart Association class and right atrial pressure significantly related to the occurrence of decompensation. Poor compliance and angina were unpredictable, infection was related to pulmonary wedge pressure, iatrogenic factors were predicted by the more advanced functional classes, whereas arrhythmias were more frequent in patients with renal failure.

Chronic Disease↗
PubMed1996

Doppler echocardiography reliably predicts pulmonary artery wedge pressure in patients with chronic heart failure with and without mitral regurgitation.

OBJECTIVES: This study was performed to assess whether the combination of multiple echocardiographic and Doppler variables can provide a reliable estimation of pulmonary artery wedge pressure in patients with chronic heart failure. BACKGROUND: In patients with chronic heart failure a high pulmonary artery wedge pressure is associated with poor prognosis, more severe symptoms and low exercise tolerance. Several Doppler echocardiographic indexes have been shown to be related to pulmonary artery wedge pressure, but the dispersion of data has generally not allowed a quantitative assessment of this important variable. METHODS: Simultaneous Doppler echocardiographic examinations and right heart catheterizations were performed in 231 patients with chronic heart failure due to dilated cardiomyopathy. Mitral and pulmonary venous flow velocity variables, left atrial volumes, mitral regurgitation jet area and left ventricular ejection fraction were correlated with pulmonary artery wedge pressure by both single and multilinear regression analysis. The reliability of the obtained multilinear equations was then tested in a separate group of 60 patients. RESULTS: By univariate analysis, the deceleration rate of early diastolic mitral flow and the systolic fraction of pulmonary venous flow showed the strongest correlations (r=0.78 and =-0.76, respectively). Stepwise regression analysis led to two multilinear equations for predicting pulmonary artery wedge pressure in the whole population: the first included only two-dimensional echocardiographic and mitral flow velocity variables (r=0.84) and the second also included pulmonary venous flow variables (r=0.87). The highest correlation was obtained (r=0.89) by a third equation in the 73 patients without significant mitral regurgitation. Correlation coefficients between estimated and measured pulmonary artery wedge pressure were 0.91 (SEE=2.7 mm Hg) and 0.97 (SEE=1.8 mm Hg) when the first and the second equation, respectively, were applied to the testing group. CONCLUSIONS: These results indicate that, in patients with chronic heart failure due to dilated cardiomyopathy, pulmonary artery wedge pressure can be reliably estimated even when mitral regurgitation is present by combining Doppler echocardiographic variables of mitral and pulmonary venous flow.

Adult↗