Search PubMed⌕ Search

Biomedical subjects

G D Pinna

Publications and source records attributed to G D Pinna.

At least 37 records · Page 2Linked to original sources
PubMed2000

Invasive and non-invasive determinants of pulmonary hypertension in patients with chronic heart failure.

BACKGROUND: In patients with chronic heart failure, pulmonary hypertension is an important predictive marker of adverse outcome. Its invasive and non-invasive determinants have not been evaluated. OBJECTIVE: This study was performed to evaluate hemodynamic determinants of pulmonary hypertension in chronic heart failure and to compare the predictive value of Doppler indices with that of invasively measured hemodynamic indices. METHODS: Right heart catheterization and transthoracic echo-Doppler were simultaneously performed in 259 consecutive patients with chronic heart failure (ejection fraction 24% +/- 7%) who were in sinus rhythm and receiving optimized medical therapy. Systolic pulmonary artery pressure (sPAP), cardiac index, transpulmonary gradient pressure, and pulmonary wedge pressure (PWP) were measured invasively. Left atrial and ventricular systolic and diastolic volumes, the ratio of maximal early to late diastolic filling velocities (E/A ratio), deceleration time (DT) and atrial filling fraction (AFF) of transmitral flow, systolic fraction of forward pulmonary venous flow (SFpvf), and mitral regurgitation were quantified by echo-Doppler. RESULTS: Patients with pulmonary hypertension had greater left atrial systolic and diastolic dysfunction, more left ventricular diastolic abnormalities, and greater hemodynamic impairment. The correlations between systolic left ventricular indices, mitral regurgitation, and sPAP were generally poor. Among invasive and non-invasive measurements, PWP (r = 0.89, p < 0.0001) and SFpvf (r = -0.68, p < 0.0001) showed the strongest correlation with sPAP. When we compared all patients with those without mitral regurgitation, the correlations between E/A ratio (r = 0.56 vs r = 0. 74, p < 0.002), SFpvf (r = -0.68 vs r = -0.84, p < 0.03), and systolic pulmonary artery pressure were significantly stronger. Multivariate analysis revealed that PWP was the strongest invasive independent predictor of systolic pulmonary artery pressure in patients with (R(2) = 0.87, p < 0.0001) and without (R(2) = 0.90, p < 0.0001) mitral regurgitation. A PWP > or= 18 mm Hg (odds ratio [95% CL], 142 (41-570) was strongly associated with systolic pulmonary hypertension. Among non-invasive variables DT, SFpvf, and AFF were identified as independent predictors of sPAP in patients with (R(2) = 0.56, p < 0.0001) and without (R(2) = 0.78, p < 0.0001) mitral regurgitation. A DT < 130 (odds ratio [95% CL], 3.5 (1.3-8.5), SFfvp < 40% (odds ratio [95% CL], 333 (41-1,007), and AFF < 30% (odds ratio [95% CL], 2 (1.3-7) most strongly predicted systolic pulmonary hypertension. CONCLUSIONS: The results of this study indicate that in patients with chronic heart failure, venous pulmonary congestion is an important determinant of systolic pulmonary artery hypertension. Hemodynamic and Doppler determinants showed similar predictive power in identifying systolic pulmonary artery hypertension.

Blood Flow Velocity↗
PubMed2000

Limitations of the computerized laryngeal analyzer (CLA) in the assessment of the swallowing mechanism.

This study was devised to assess the repeatability of measurements obtained from the Computerized Laryngeal Analyzer (CLA), a commercial system which monitors global laryngeal activity through a piezoelectric transducer positioned at the level of the thyroid cartilage. Twenty-two healthy subjects (37+/-7 yr) were asked to repeat three consecutive times the deglutition of three types of bolus: dry (saliva only), liquid (10 ml water) and solid (1 cm(3) biscuit). The whole recording session was repeated 4+/-3 days apart. Two parameters were considered: amplitude and duration of the deglutition. Both intra- and inter-sessions repeatability were assessed by the standard error of measurement. The amplitude measurements were often found to be clipped at 100 mV, making duration the only parameter suitable for analysis. The duration was homogenous for the three types of bolus and no trend effect was found either intra- or inter-sessions. Inter-sessions repeatability was significantly lower than the intra-session one (P<0.05). As a practical implication, a change in duration >/=1 s (=65% of the observed mean value) between two separate measurements is required in order to be 95% confident that it is not due to chance alone. We conclude that the observed limitations in the measurements provided by the CLA system, in conjunction with its intrinsic characteristic of providing only an uncalibrated measurement of global laryngeal activity, seriously question the possibility of using the CLA system either as a diagnostic tool or as a substitute of the gold standard method (videofluorography).

Adult↗
PubMed2000

Comparison between invasive and non-invasive measurements of baroreflex sensitivity; implications for studies on risk stratification after a myocardial infarction.

AIMS: The ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study has proved the independent prognostic value of baroreflex sensitivity. A limitation of the traditional method of estimating baroreflex sensitivity by phenylephrine, is the need to monitor intra-arterial blood pressure. Our objective was to establish whether this invasive method of monitoring could be superseded by non-invasive methods, such as the Finapres device. METHODS AND RESULTS: Patients with three repeated invasive and non-invasive baroreflex sensitivity measurements were selected from the ATRAMI database (n = 454). The mean of these measurements was taken as the baroreflex sensitivity estimate. The repeatability of both methods (standard deviation of the three measurements) decreased with increasing baroreflex sensitivity. There was no constant bias between invasive and non-invasive measurements (0. 22+/-2.2 ms. mmHg(-1), P = 0.42). The linear correlation was very high (r = 0.91, P < 0.01). The normalized 95% limits of agreement were -0.5 and 0.52. On survival analysis, invasive and non-invasive baroreflex sensitivity gave similar prognostic information (likelihood ratio: 155.6 (P = 0.007) and 155.0 (P = 0.006); risk ratio: 0.79 and 0.81, respectively). According to the ATRAMI cut-off points, 85% of patients were classified concordantly by the two methods. None of the patients at high (low) risk with the invasive method were classified as low (high) risk class by the non-invasive method. CONCLUSION: Despite wide limits of agreement, invasive and non-invasive baroreflex sensitivity measurements are highly correlated and provide equivalent prognostic information.

Autonomic Nervous System↗
PubMed2000

Effect of beta-blockade on the premature ventricular beats/heart rate relation and heart rate variability in patients with coronary heart disease and severe ventricular arrhythmias.

We examined the effects of beta-blockers on the associations between heart rate and number of premature ventricular beats (PVBs) and on heart rate variability and myocardial ischemia in patients with coronary heart disease. After 2 weeks of run-in placebo treatment, 18 patients with coronary artery disease were randomized to a 7-day treatment with either propranolol (40 mg) three times a day or placebo. During run-in and after 7 days of treatment, patients underwent 24-hour Holter monitoring and exercise tests. We analyzed the 24-hour Holter recordings with customized software that computes the correlation between heart rate and occurrence of PVBs. We also computed spectral measures of heart rate variability on the same recordings. Propranolol caused a significant decrease in the log-transformed total number of PVBs recorded over 24 hours and during the day. The number of PVBs was much lower during the night than during the day both after placebo and after propranolol. There were no differences between the two treatments. During the day, there was a positive correlation between heart rate and the number of PVBs in all 18 patients. The mean correlation coefficients between heart rate and number of PVBs increased significantly after propranolol treatment both during the 24-hour monitoring (p < 0.05) and during the day (p < 0.05). The night-recorded correlation coefficients between heart rate and number of PVBs were not significantly different in the placebo versus propranolol group. Propranolol significantly increased the total power during the day. Placebo caused a significant decrease in the low-frequency band (LF) and a significant increase in the high-frequency band (HF) during the night compared with the day. During the day, propranolol significantly reduced LF power and increased HF power, with respect to placebo. After propranolol treatment, the values of LF and HF power during the day were comparable to those recorded at night. The LF/HF ratio decreased significantly after propranolol treatment with respect to placebo in the day and became similar to that recorded during sleep. Propranolol significantly reduced heart rate and systolic blood pressure at rest and at peak exercise and reduced signs of myocardial ischemia. Propranolol administration reduces PVBs in patients with coronary artery disease and severe ventricular arrhythmias possibly through an improvement of cardiac autonomic regulation and through anti-ischemic effects, antiarrhythmic effects, or both.

Adrenergic beta-Antagonists↗
PubMed2000

Cardiorespiratory interactions during periodic breathing in awake chronic heart failure patients.

We applied spectral techniques to the analysis of cardiorespiratory signals [instantaneous lung volume (ILV), instantaneous tidal volume (ITV), arterial O(2) saturation (Sa(O(2))) at the ear, heart rate (HR), systolic (SAP), and diastolic (DAP) arterial pressure] during nonapneic periodic breathing (PB) in 29 awake chronic heart failure (CHF) patients and estimated the timing relationships between respiratory and slow cardiovascular (<0.04 Hz) oscillations. Our aim was 1) to elucidate major mechanisms involved in cardiorespiratory interactions during PB and 2) to test the hypothesis of a central vasomotor origin of PB. All cardiovascular signals were characterized by a dominant (>/=84% of total power) oscillation at the frequency of PB (mean +/- SE: 0.022 +/- 0.0008 Hz), highly coherent (>/=0.89), and delayed with respect to ITV (ITV-HR, 2.4 +/- 0.72 s; ITV-SAP, 6.7 +/- 0.65 s; ITV-DAP, 3.2 +/- 0.61 s; P < 0.01). Sa(O(2)) was highly coherent with (coherence function = 0.96 +/- 0. 009) and almost opposite in phase to ITV. These findings demonstrate the existence of a generalized cardiorespiratory rhythm led by the ventilatory oscillation and suggest that 1) the cyclic increase in inspiratory drive and cardiopulmonary reflexes and 2) mechanical effects of PB-induced changes in intrathoracic pressure are the more likely sources of the HR and blood pressure oscillations, respectively. The timing relationship between ITV and blood pressure signals excludes the possibility that PB represents the effect of a central vasomotor rhythm.

Arteries↗
PubMed2000

Periodic breathing in heart failure patients: testing the hypothesis of instability of the chemoreflex loop.

In this study, we applied time- and frequency-domain signal processing techniques to the analysis of respiratory and arterial O(2) saturation (Sa(O(2))) oscillations during nonapneic periodic breathing (PB) in 37 supine awake chronic heart failure patients. O(2) was administered to eight of them at 3 l/min. Instantaneous tidal volume and instantaneous minute ventilation (IMV) signals were obtained from the lung volume signal. The main objectives were to verify 1) whether the timing relationship between IMV and Sa(O(2)) was consistent with modeling predictions derived from the instability hypothesis of PB and 2) whether O(2) administration, by decreasing loop gain and increasing O(2) stores, would have increased system stability reducing or abolishing the ventilatory oscillation. PB was centered around 0.021 Hz, whereas respiratory rate was centered around 0.33 Hz and was almost stable between hyperventilation and hypopnea. The average phase shift between IMV and Sa(O(2)) at the PB frequency was 205 degrees (95% confidence interval 198-212 degrees). In 12 of 37 patients in whom we measured the pure circulatory delay, the predicted lung-to-ear delay was 28.8 +/- 5.2 s and the corresponding observed delay was 30.9 +/- 8.8 s (P = 0.13). In seven of eight patients, O(2) administration abolished PB (in the eighth patient, Sa(O(2)) did not increase). These results show a remarkable consistency between theoretical expectations derived from the instability hypothesis and experimental observations and clearly indicate that a condition of loss of stability in the chemical feedback control of ventilation might play a determinant role in the genesis of PB in awake chronic heart failure patients.

Arteries↗
PubMed1999

Association between hemodynamic impairment and Cheyne-Stokes respiration and periodic breathing in chronic stable congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

Irregular breathing occurs frequently in patients with congestive heart failure (CHF) both during daytime and nighttime. Many factors are involved in the genesis of these breathing abnormalities, but the role of the hemodynamic impairment remains controversial. This study investigated the relation between worsening ventricular function and the frequency of respiratory disorders in patients with mild to severe CHF. One hundred fifty patients with CHF (mean age 53 +/- 8 years, left ventricular (LV) ejection fraction 26 +/- 7, in New York Heart Association [NYHA] classes II to IV, and who underwent stable therapy for > or =2 weeks) were studied. Analysis of instantaneous lung volume signal and arterial oxygen saturation during awake daytime revealed a normal respiratory pattern in 63 patients, whereas 87 had a persistent alteration of breathing, with a typical Cheyne-Stokes respiration (CSR) in 42 and periodic breathing (PB [oscillation of tidal volumes without apnea]) in 45 patients. Patients with PB and CSR showed a more pronounced hemodynamic impairment with a significantly reduced cardiac index, an increased pulmonary arterial wedge pressure, and a longer lung-to-ear circulation time (LECT) compared with patients with normal respiratory patterns. In a logistic regression model that included all of the variables significantly associated with breathing disorders, cardiac index and LECT emerged as the major determinants of CSR. In those patients with LECT > or =30 seconds (upper quartile) and cardiac index < or =1.9 L/min/m2 (lower quartiles), the incidence of CSR was significantly higher (69%) than in patients with lower LECT and higher cardiac index (14%, p <0.001). In conclusion, abnormalities of breathing activity during daytime are significantly associated with a prolonged circulation time and a more severe impairment of systolic and diastolic LV indexes.

Analysis of Variance↗
PubMed1999

Arterial baroreflex modulation of heart rate in patients early after heart transplantation: lack of parasympathetic reinnervation.

BACKGROUND: Orthotopic heart transplantation results in cardiac denervation. The presence of cardiac parasympathetic reinnervation in humans has been widely debated based on the application of differing indirect measures of autonomic control. However no attempt has been made to analyse the reflex heart rate response to baroreceptor stimulation whose occurrence is generally considered a reliable marker of the ability to activate cardiac vagal reflexes. This study tested the hypothesis that the presence of donor heart RR interval lengthening following phenylephrine induced blood pressure increase would be an index of parasympathetic reinnervation. METHODS: Baroreflex sensitivity (BRS) was assessed in 30 patients (mean age 51+/-12 years) 1-24 months after heart transplantation carried out by the standard Lower-Shumway technique. In 6 patients the recipient atrium rate response (P-P interval) to baroreceptor stimulation by phenylephrine was also simultaneously determined by transesophageal recording. RESULTS: None of the 30 patients showed prolongation of RR intervals in the donor heart. The average BRS value was -0.28+/-0.54 ms/mmHg (range -1.3-0.7 ms/mm Hg). In the 6 patients in whom BRS was obtained at both the recipient atrium (P-P) and donor heart (R-R) the changes were 7.6+/-5.7 ms/mm Hg and -0.38+/-0.58 ms/mm Hg respectively (p = 0.02), thus confirming that the absent RR interval lengthening in the donor heart is the consequence of efferent vagal fiber interruption. CONCLUSIONS: The absence of any RR interval prolongation following phenylephrine induced baroreceptor stimulation demonstrates that vagal efferent reinnervation of the donor heart does not occur up to 24 months in patients operated via the standard Lower-Shumway procedure. It is also suggested that analysis of baroreceptor reflexes is a more specific method in the examination of cardiac parasympathetic reinnervation.

Arteries↗
PubMed1999

Time trends in the intracardiac potential recorded by pacemaker telemetry: comparison between steroid-eluting small area electrodes.

We assessed the time course of electrograms sensed both in the atrium and ventricle by two different steroid-eluting electrodes: Medtronic Capsure SP (with an area of 5.5 mm2) and Z (with an area of 1.2 mm2). We considered 68 unipolar electrodes: 31 atrial (19 Capsure SP 4523 and 12 Capsure Z 4533) and 37 ventricular (24 Capsure SP 4023 and 13 Capsure Z 4033) implanted in 47 consecutive patients (30 men and 17 women, with an age of 72 +/- 9.4 years). The pacemaker model was Medtronic Elite 7077-7086 (DDD-DDDR) in 25 patients and Medtronic Legend 8419-8424 (VVIR-AAIR) in 22 patients. The endocavitary signal (all patients had spontaneous rhythm) was telemetrically obtained by a Medtronic 9790 device and acquired on a personal computer at implantation and 7, 30, and 180 days thereafter. The signal was studied both in the time domain and in the frequency domain by spectral analysis. The following parameters were calculated: amplitude (A): peak-to-peak value of the complex; slew rate (SR) peak negative first derivative; F0: frequency at which the power spectrum reaches its maximum value; and bandwidth (Bw): expressed as the distance between the -3 dB points and statistically analyzed by a two-way analysis of variance with factors "time" (four measurements) and "electrode" (Capsure SP and Z) and repeated measurements on the former. Ventricular sensing: no time or electrode effect (P > 0.1 in all comparisons) was found for F0, Bw, or SR, while a time effect (P < 0.04) not dependent on the type of electrode was found for the amplitude of the signal. In particular, a significant increase was found between the measurement at 6 months and that at implantation (P < 0.004). Atrial sensing: A, F0, and bandwidth were not affected by time or electrode (P > 0.09), while SR behaved differently over time (P < 0.05) in the two electrodes (the Capsure Z showed an increase at sixth month [P < 0.04] compared to implantation). In conclusion, the Medtronic Capsure SP and Z electrodes proved to be valid and substantially equivalent as far as concerns the measurement of the intracardiac potential despite the difference between their surface areas. Further studies should be devised to assess whether transitory decreases of atrial Bw in the first month of follow-up observed in a few patients for both electrodes could be responsible for clinical episodes of sensing deficit.

Aged↗
PubMed1998

Peak exercise oxygen consumption in chronic heart failure: toward efficient use in the individual patient.

OBJECTIVES: This study sought to 1) assess the short-, medium-and long-term prognostic power of peak oxygen consumption (VO2) in patients with heart failure; 2) verify the consistency of a nonmeasurable anaerobic threshold (AT) as a criterion of nonapplicability of peak VO2; 3) develop simple rules for the efficient use of peak VO2 in individualized prognostic stratification and clinical decision making. BACKGROUND: Peak VO2, when AT is identified, is among the indicators for heart transplant eligibility. However, in clinical practice the application of defined peak VO2 cutoff values to all patients could be inappropriate and misleading. METHODS: Six hundred fifty-three patients consecutively considered for eligibility for heart transplantation were followed up. Outcomes (cardiac death and urgent transplantation) were determined when all survivors had a minimum of 6 months of follow-up. RESULTS: Contraindication to the exercise test identified very high risk patients. The relatively small sample of women did not allow inferences to be drawn. In men, peak VO2 stratified into three levels (< or = 10, 10 to 18 and >18 ml/kg per min) identified groups at high, medium and low risk, respectively. The prognostic power of peak VO2 < or = 10 ml/kg per min was maintained even when the AT was not detected. In patients in New York Heart Association functional class III or IV, peak VO2 did not have prognostic power. In patients in functional class I or II, peak VO2 stratification was prognostically valuable, but less so at 6 than at 12 or 24 months. Age did not influence peak VO2 prognostic stratification. CONCLUSIONS: A contraindication to exercise testing should be considered a priority for listing patients for heart transplantation. Only in less symptomatic male patients does a peak VO2 < or = 10 ml/kg per min identify short-, medium- and long-term high risk groups. A peak VO2 >18 ml/kg per min implies good prognosis with medical therapy.

Anaerobic Threshold↗
PubMed1998

POLYAN: a computer program for polyparametric analysis of cardio-respiratory variability signals.

A polyparametric approach to the study of cardiovascular and respiratory systems, with the analysis of several simultaneously recorded signals and of their mutual relationships, is essential for the assessment of autonomic regulation. A computer program which implements all the procedures used in this investigative context and also makes the approach easy for researchers without an engineering background is described. Spectral techniques (univariate and bivariate), time domain techniques and non invasive baroreflex sensitivity assessment are available and integrated in the same package. In order to allow the flexibility and easy expandability required in a research tool, POLYAN was written in Matlab. POLYAN is currently used in our Hospital by several research groups and is a fundamental research tool for the interdisciplinary assessment of the autonomic nervous system. Establishing a common analysis framework, POLYAN has made sharing new findings and co-operating in research work much easier.

Cardiovascular Physiological Phenomena↗
PubMed1998

Assessing baroreflex sensitivity in post-myocardial infarction patients: comparison of spectral and phenylephrine techniques.

OBJECTIVES: This study sought to compare, in post-myocardial infarction patients, baroreflex sensitivity (BRS) measured by the phenylephrine method (Phe-BRS) with that estimated by the Robbe (Robbe-BRS) and Pagani (alpha-low frequency [LF] and alpha-high frequency [HF]) spectral techniques. BACKGROUND: BRS assessed by Phe-BRS has been shown to be of prognostic value in patients with a previous myocardial infarction, but the need for drug injection limits the use of this technique. Several noninvasive methods based on spectral analysis of systolic arterial pressure and heart period have been proposed, but their agreement with Phe-BRS has never been investigated in post-myocardial infarction patients. METHODS: The linear association and the agreement between each spectral measurement and Phe-BRS were assessed by correlation analysis and by computing the relative bias and the limits of agreement in 51 post-myocardial infarction patients. RESULTS: The correlation with Phe-BRS was r = 0.63 for Robbe-BRS, r = 0.62 for alpha-LF and r = 0.59 for alpha-HF. The relative bias was significant for alpha-LF (2.6 ms/mm Hg, p < 0.001) and alpha-HF (2.5 ms/mm Hg, p = 0.01) and not significant (-0.6 ms/mm Hg, p = 0.3) for Robbe-BRS. The normalized limits of agreement ranged from -98% to 95% for Robbe-BRS, from -67% to 126% for alpha-LF and from -108% to 143% for alpha-HF. When patients were classified according to left ventricular ejection fraction (LVEF, cutoff value 40%), the relative bias was higher in patients with a depressed LVEF, although statistical significance was high only for Robbe-BRS and was borderline for alpha-LF. The limits of agreement were similar in both groups of patients (p > 0.3). CONCLUSIONS: Despite a substantial linear association, the agreement between spectral measurements and Phe-BRS in post-myocardial infarction patients is weak because the difference can be as large as the BRS value being estimated. Phe-BRS is the measurement most associated with hemodynamic impairment. Because several factors within each method contribute to the overall difference, neither method can be defined as being better than the other in estimating baroreflex gain, nor can one be used as an alternative to the other. Ad hoc studies are needed to assess which method provides the most useful physiologic or pathophysiologic information or the most accurate prediction of prognosis.

Baroreflex↗
PubMed1998

Predictors of primary atrial fibrillation and concomitant clinical and hemodynamic changes in patients with chronic heart failure: a prospective study in 344 patients with baseline sinus rhythm.

OBJECTIVES: This study investigated the incidence, predisposing factors and significance of the onset of atrial fibrillation (AF) in patients with chronic congestive heart failure (CHF). BACKGROUND: The association between CHF and AF is well documented, but the factors that predispose to the onset of the arrhythmia and its impact remain controversial. Methods. We prospectively followed up 344 patients with CHF and sinus rhythm (SR). Over a period of 19 +/- 12 months (mean +/- SD), 28 patients developed atrial fibrillation (AF), which became chronic in 18. RESULTS: At baseline, no differences were found in any clinical and hemodynamic variables between patients who developed chronic AF and those who did not. Reversible AF occurring during follow-up and lower mitral flow velocity at atrial contraction as detected at the last evaluation in SR were independent predictors of the subsequent development of chronic AF. When AF occurred, New York Heart Association functional class worsened (from 2.4 +/- 0.5 to 2.9 +/- 0.6, p = 0.0001), peak exercise oxygen consumption declined (from 16 +/- 5 to 11 +/- 5 ml/kg per min, p = 0.002), cardiac index decreased (from 2.2 +/- 0.4 to 1.8 +/- 0.4, p = 0.0008), and mitral and tricuspid regurgitation increased (from grade 1.8 +/- 1.1 to grade 2.4 +/- 1.4, p = 0.0001 and from grade 1.0 +/- 1.2 to grade 1.8 +/- 1.2, p = 0.001, respectively). Systemic thromboembolism occurred in 3 of the 18 patients with AF. Nine of 18 patients died after AF, and the occurrence of AF was a predictor of major cardiac events. CONCLUSIONS: In patients with CHF, reversible AF and reduction of left atrial contribution to left ventricular filling predict the subsequent development of chronic AF. The onset of AF is associated with clinical and hemodynamic deterioration and may predispose to systemic thromboembolism and poorer prognosis.

Adult↗
PubMed1998

The development of hyperventilation in patients with chronic heart failure and Cheyne-Strokes respiration: a possible role of chronic hypoxia.

AIM: To analyze the relationship between daytime respiratory and cardiac function in patients with compensated chronic heart failure (CHF) with and without periodic breathing (PB) or Cheyne-Stokes respiration (CSR). PATIENTS: We studied 132 patients (female, 13%; mean age, 53+/-8 years; body mass index, 25.9+/-3.5 kg/m2; left ventricular ejection fraction <40%; 23% in New York Heart Association class I, 43% in class II, and 34% in class III-IV). METHODS: Measurement of pulmonary function and blood gases, hemodynamic evaluation, analysis of breathing profile, echocardiography, recording of ECG, beat-to-beat arterial oxygen saturation, and respiration during spontaneous breathing. RESULTS: Fifty-eight percent of patients showed PB or CSR. Patients with PB or CSR have greater cardiac function impairment. Mean values of lung volumes and PaO2 were similar in the three groups of patients considered. In contrast, patients with PB or CSR had an increased minute ventilation and reduced PaCO2 values. Interestingly, patients with PB or CSR had lower values of arterial content of O2 and systemic oxygen transport (SOT) than patients with a normal breathing pattern (SOT, 394+/-9.8, 347+/-9.6, 438+/-11 mL of O2/min/m2, respectively; analysis of variance p<0.001). Weak correlations were found among lung volumes, blood gases, and cardiac function parameters: ie, vital capacity was correlated inversely with pulmonary capillary wedge pressure (PCWP) (-0.25; p<0.05); PaCO2 with PCWP (r=0.26; p<0.05), lung-to-ear circulation time (LECT) (r=-0.4; p<0.05), SOT (r=-0.33; p<0.0001), and cardiac index (CI) (r=0.27; p=0.003). Multiple regression analyses showed that arterial PCO2 was significantly correlated with SOT, LECT, and CI (r=0.51; r2=0.26; p<0.000001); the correlation became stronger considering only CSR patients (r=0.64; r2=0.4; p<0.001). CONCLUSIONS: Our study shows that patients with daytime breathing disorders have chronic hypocapnia. A reduced SOT may be one of the stimuli determining increased minute ventilation in these patients.

Cheyne-Stokes Respiration↗
PubMed1998

[An analysis of the decision process in the pharmacological treatment of a patient with chronic heart failure by means of a therapy management information system: the experience of the Montescano Heart Failure Unit].

A computer-based system integrated into the hospital information system for the pharmacological management of the chronic heart-failure patients admitted to the heart-failure unit of Montescano is presented. The major aims of the system involved monitoring the patients' treatment history and the related therapeutic decision-making. The treatment history of the first 151 consecutive CHF patients admitted after the system implementation is examined. The prescribed drug doses at admission and at discharge are compared, as well as the differences in etiology and NYHA class between patients discharged with or without each drug. Several considerations can be drawn from this analysis. First of all, in heart failure patients the choice of drugs is limited and optimal treatment is a result of individualized dosages. Secondly, time and trials are necessary to obtain optimal treatment. Consequently, continuity of care and in- and out-hospital networks are advisable. Third, a computer-based system offers advantages not only for the pharmacological management itself, but also for improving the quality of care through continuous analysis of the decision-making process.

Cardiology Service, Hospital↗
PubMed1997

Arterial baroreflex modulation of heart rate in chronic heart failure: clinical and hemodynamic correlates and prognostic implications.

BACKGROUND: In chronic heart failure (CHF), arterial baroreflex regulation of cardiac function is impaired, leading to a reduction in the tonic restraining influence on the sympathetic nervous system. Because baroreflex sensitivity (BRS), as assessed by the phenylephrine technique, significantly contributes to postinfarction risk stratification, the aim of the present study was to evaluate whether in CHF patients a depressed BRS is associated with a worse clinical hemodynamic status and unfavorable outcome. METHODS AND RESULTS: BRS was assessed in 282 CHF patients in sinus rhythm receiving stable medical therapy (age, 52+/-9 years; New York Heart Association [NYHA] class, 2.4+/-0.6; left ventricular ejection fraction [LVEF], 23+/-6%). The BRS of the entire population averaged 3.9+/-4.0 ms/mm Hg (mean+/-SD) and was significantly related to LVEF and hemodynamic parameters (LVEF, P<.005; cardiac index and pulmonary wedge pressure, P<.001 by regression analysis). Patients in NYHA classes III or IV and those with severe mitral regurgitation had markedly depressed vagal reflexes. The association of BRS with survival was described after its categorization in three groups: below the lowest quartile (<1.3 ms/mm Hg), between the lowest quartile and the median (1.3 to 3 ms/mm Hg), and above the median (>3 ms/mm Hg). During a mean follow-up of 15+/-12 months, 78 primary events (cardiac death, nonfatal cardiac arrest, and status 1 priority transplantation) occurred (27.6%). BRS was significantly related to outcome (log rank, 9.1; P<.01), with a relative risk of 2.7 (95% confidence interval, 1.6 to 4.7) for patients with the major derangement in BRS (<1.3 ms/mm Hg). At multivariate analysis, BRS was an independent predictor of death after adjustment for noninvasive known risk factors but not when hemodynamic indexes were also considered. In CHF patients with severe mitral regurgitation, however, BRS remained a strong prognostic marker independent of hemodynamic function. CONCLUSIONS: In moderate to severe CHF, a depressed sensitivity of vagal reflexes parallels the deterioration of clinical and hemodynamic status and is significantly associated with poor survival. Particularly in patients with severe mitral regurgitation the baroreceptor modulation of heart rate provides prognostic information of incremental value to hemodynamic parameters.

Adult↗
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↗