Alanine Scanning of the Unstructured Region of Ara h 2 and of a Related Mimotope Reveals Critical Amino Acids for IgE Binding

SCOPE

The unstructured region of Ara h 2, referred to as epitope 3, contains a repeated motif, DYPSh (h = hydroxyproline) that is important for IgE binding.

METHODS AND RESULTS

IgE binding assays to 20mer and shorter peptides of epitope 3, defines a 16mer core sequence containing one copy of the DPYSh motif, DEDSYERDPYShSQDP. This study performs alanine scanning of this and a related 12mer mimotope, LLDPYAhRAWTK. IgE binding, using a pool of 10 sera and with individual sera, is greatly reduced when alanine is substituted for aspartate at position 8 (D8; p < 0.01), tyrosine at position 10 (Y10; p < 0.01), and hydroxyproline at position 12 (h12; p < 0.001). IgE binding to alanine-substituted peptides of a mimotope containing the DPY_h motif confirm the critical importance of Y (p < 0.01) and h (p < 0.01), but not D. Molecular modeling of the core and mimotope suggests an h-dependent conformational basis for the recognition of these sequences by polyclonal IgE.

CONCLUSIONS

IgE from pooled sera and individual sera differentially bound amino acids throughout the sequences of Epitope 3 and its mimotope, with Y10 and h12 being most important for all sera. These results are highly significant for designing hypoallergenic forms of Ara h 2.

Defining the Roles of Cardiokines in Human Aging and Age-Associated Diseases

In recent years an expanding collection of heart-secreted signaling proteins have been discovered that play cellular communication roles in diverse pathophysiological processes. This minireview briefly discusses current evidence for the roles of cardiokines in systemic regulation of aging and age-associated diseases. An analysis of human transcriptome and secretome data suggests the possibility that many other cardiokines remain to be discovered that may function in long-range physiological regulations. We discuss the ongoing challenges and emerging technologies for elucidating the identity and function of cardiokines in endocrine regulations.

Decreases in Gap Junction Coupling Recovers Ca2+ and Insulin Secretion in Neonatal Diabetes Mellitus, Dependent on Beta Cell Heterogeneity and Noise

Diabetes is caused by dysfunction to β-cells in the islets of Langerhans, disrupting insulin secretion and glucose homeostasis. Gap junction-mediated electrical coupling between β-cells in the islet plays a major role in coordinating a pulsatile secretory response at elevated glucose and suppressing insulin secretion at basal glucose. Previously, we demonstrated that a critical number of inexcitable cells can rapidly suppress the overall islet response, as a result of gap junction coupling. This was demonstrated in a murine model of Neonatal Diabetes Mellitus (NDM) involving expression of ATP-insensitive K_ATP channels, and by a multi-cellular computational model of islet electrical activity. Here we examined the mechanisms by which gap junction coupling contributes to islet dysfunction in NDM. We first verified the computational model against [Ca²⁺] and insulin secretion measurements in islets expressing ATP-insensitive K_ATP channels under different levels of gap junction coupling. We then applied this model to predict how different K_ATP channel mutations found in NDM suppress [Ca²⁺], and the role of gap junction coupling in this suppression. We further extended the model to account for stochastic noise and insulin secretion dynamics. We found experimentally and in the islet model that reductions in gap junction coupling allow progressively greater glucose-stimulated [Ca²⁺] and insulin secretion following expression of ATP-insensitive K_ATP channels. The model demonstrated good correspondence between suppression of [Ca²⁺] and clinical presentation of different NDM mutations. Significant recoveries in [Ca²⁺] and insulin secretion were predicted for many mutations upon reductions in gap junction coupling, where stochastic noise played a significant role in the recoveries. These findings provide new understanding how the islet functions as a multicellular system and for the role of gap junction channels in exacerbating the effects of decreased cellular excitability. They further suggest novel therapeutic options for NDM and other monogenic forms of diabetes.

Diabetes is a disease reaching a global epidemic, which results from dysfunction to the islets of Langerhans in the pancreas and their ability to secrete the hormone insulin to regulate glucose homeostasis. Islets are multicellular structures that show extensive coupling between heterogeneous cellular units; and central to the causes of diabetes is a dysfunction to these cellular units and their interactions. Understanding the inter-relationship between structure and function is challenging in biological systems, but is crucial to the cause of disease and discovering therapeutic targets. With the goal of further characterizing the islet of Langerhans and its excitable behavior, we examined the role of important channels in the islet where dysfunction is linked to or causes diabetes. Advances in our ability to computationally model perturbations in physiological systems has allowed for the testing of hypothesis quickly, in systems that are not experimentally accessible. Using an experimentally validated model and modeling human mutations, we discover that monogenic forms of diabetes may be remedied by a reduction in electrical coupling between cells; either alone or in conjunction with pharmacological intervention. Knowledge of biological systems in general is also helped by these findings, in that small changes to cellular elements may lead to major disruptions in the overall system. This may then be overcome by allowing the system components to function independently in the presence of dysfunction to individual cells.

Fluorescence recovery after photobleaching reveals regulation and distribution of connexin36 gap junction coupling within mouse islets of Langerhans

The pancreatic islets are central to the maintenance of glucose homeostasis through insulin secretion. Glucose‐stimulated insulin secretion is tightly linked to electrical activity in β cells within the islet. Gap junctions, composed of connexin36 (Cx36), form intercellular channels between β cells, synchronizing electrical activity and insulin secretion. Loss of gap junction coupling leads to altered insulin secretion dynamics and disrupted glucose homeostasis. Gap junction coupling is known to be disrupted in mouse models of pre‐diabetes. Although approaches to measure gap junction coupling have been devised, they either lack cell specificity, suitable quantification of coupling or spatial resolution, or are invasive. The purpose of this study was to develop fluorescence recovery after photobleaching (FRAP) as a technique to accurately and robustly measure gap junction coupling in the islet. The cationic dye Rhodamine 123 was used with FRAP to quantify dye diffusion between islet β cells as a measure of Cx36 gap junction coupling. Measurements in islets with reduced Cx36 verified the accuracy of this technique in distinguishing between distinct levels of gap junction coupling. Analysis of individual cells revealed that the distribution of coupling across the islet is highly heterogeneous. Analysis of several modulators of gap junction coupling revealed glucose‐ and cAMP‐dependent modulation of gap junction coupling in islets. Finally, FRAP was used to determine cell population specific coupling, where no functional gap junction coupling was observed between α cells and β cells in the islet. The results of this study show FRAP to be a robust technique which provides the cellular resolution to quantify the distribution and regulation of Cx36 gap junction coupling in specific cell populations within the islet. Future studies utilizing this technique may elucidate the role of gap junction coupling in the progression of diabetes and identify mechanisms of gap junction regulation for potential therapies.

Phase transitions in the multi-cellular regulatory behavior of pancreatic islet excitability

The pancreatic islets of Langerhans are multicellular micro-organs integral to maintaining glucose homeostasis through secretion of the hormone insulin. β-cells within the islet exist as a highly coupled electrical network which coordinates electrical activity and insulin release at high glucose, but leads to global suppression at basal glucose. Despite its importance, how network dynamics generate this emergent binary on/off behavior remains to be elucidated. Previous work has suggested that a small threshold of quiescent cells is able to suppress the entire network. By modeling the islet as a Boolean network, we predicted a phase-transition between globally active and inactive states would emerge near this threshold number of cells, indicative of critical behavior. This was tested using islets with an inducible-expression mutation which renders defined numbers of cells electrically inactive, together with pharmacological modulation of electrical activity. This was combined with real-time imaging of intracellular free-calcium activity [Ca²⁺]_i and measurement of physiological parameters in mice. As the number of inexcitable cells was increased beyond ∼15%, a phase-transition in islet activity occurred, switching from globally active wild-type behavior to global quiescence. This phase-transition was also seen in insulin secretion and blood glucose, indicating physiological impact. This behavior was reproduced in a multicellular dynamical model suggesting critical behavior in the islet may obey general properties of coupled heterogeneous networks. This study represents the first detailed explanation for how the islet facilitates inhibitory activity in spite of a heterogeneous cell population, as well as the role this plays in diabetes and its reversal. We further explain how islets utilize this critical behavior to leverage cellular heterogeneity and coordinate a robust insulin response with high dynamic range. These findings also give new insight into emergent multicellular dynamics in general which are applicable to many coupled physiological systems, specifically where inhibitory dynamics result from coupled networks.

As science has successfully broken down the elements of many biological systems, the network dynamics of large-scale cellular interactions has emerged as a new frontier. One way to understand how dynamical elements within large networks behave collectively is via mathematical modeling. Diabetes, which is of increasing international concern, is commonly caused by a deterioration of these complex dynamics in a highly coupled micro-organ called the islet of Langerhans. Therefore, if we are to understand diabetes and how to treat it, we must understand how coupling affects ensemble dynamics. While the role of network connectivity in islet excitation under stimulatory conditions has been well studied, how connectivity also suppresses activity under fasting conditions remains to be elucidated. Here we use two network models of islet connectivity to investigate this process. Using genetically altered islets and pharmacological treatments, we show how suppression of islet activity is solely dependent on a threshold number of inactive cells. We found that the islet exhibits critical behavior in the threshold region, rapidly transitioning from global activity to inactivity. We therefore propose how the islet and multicellular systems in general can generate a robust stimulated response from a heterogeneous cell population.

Decreasing cx36 gap junction coupling compensates for overactive KATP channels to restore insulin secretion and prevent hyperglycemia in a mouse model of neonatal diabetes

Mutations to the ATP-sensitive K(+) channel (KATP channel) that reduce the sensitivity of ATP inhibition cause neonatal diabetes mellitus via suppression of β-cell glucose-stimulated free calcium activity ([Ca(2+)]i) and insulin secretion. Connexin-36 (Cx36) gap junctions also regulate islet electrical activity; upon knockout of Cx36, β-cells show [Ca(2+)]i elevations at basal glucose. We hypothesized that in the presence of overactive ATP-insensitive KATP channels, a reduction in Cx36 would allow elevations in glucose-stimulated [Ca(2+)]i and insulin secretion to improve glucose homeostasis. To test this, we introduced a genetic knockout of Cx36 into mice that express ATP-insensitive KATP channels and measured glucose homeostasis and islet metabolic, electrical, and insulin secretion responses. In the normal presence of Cx36, after expression of ATP-insensitive KATP channels, blood glucose levels rapidly rose to >500 mg/dL. Islets from these mice showed reduced glucose-stimulated [Ca(2+)]i and no insulin secretion. In mice lacking Cx36 after expression of ATP-insensitive KATP channels, normal glucose levels were maintained. Islets from these mice had near-normal glucose-stimulated [Ca(2+)]i and insulin secretion. We therefore demonstrate a novel mechanism by which islet function can be recovered in a monogenic model of diabetes. A reduction of gap junction coupling allows sufficient glucose-stimulated [Ca(2+)]i and insulin secretion to prevent the emergence of diabetes.

Visualization of left atrial appendage and assessment of its function by transthoracic second harmonic imaging and contrast-enhanced pulsed Doppler

BACKGROUND

Low flow velocity within the left atrial appendage, as assessed by transoesophageal echocardiography, is a predictor of thromboembolism and of a low success rate of cardioversion of atrial fibrillation. However, the semi-invasive nature does limit its serial application as a screening technique.

METHODS AND RESULTS

We investigated the value of transthoracic second harmonic echocardiography and pulsed Doppler at baseline and after intravenous contrast injection to visualize the left atrial appendage and assess blood flow velocities within its cavity. We studied 51 consecutive patients undergoing transoesophageal echocardiography. After transoesophageal echocardiography, transthoracic second harmonic imaging was performed and the left atrial appendage was visualized in 46 patients. Interpretable pulsed Doppler tracings of left atrial appendage flow were obtained at baseline in 39 patients and in 45 patients during Levovist administration. The correlations between peak emptying velocity of left atrial appendage as measured by transoesophageal echocardiography and by transthoracic standard and contrast-enhanced Doppler were 0.81 and 0.91, respectively. The agreement between transoesophageal echocardiography and transthoracic contrast-enhanced pulsed Doppler echocardiography in classifying left atrial appendage flow velocity patterns was 93%. Left atrial appendage thrombus was detected by transthoracic second harmonic imaging in only one of the eight patients shown by transoesophageal echocardiography to have a thrombus. However, all but one of the patients with left atrial appendage thrombus and/or spontaneous echocardiographic contrast at transoesophageal echocardiography had <30cm/s left atrial appendage flow velocity by transthoracic Doppler.

CONCLUSIONS

This study shows that left atrial appendage can be visualized by transthoracic second harmonic imaging and that the flow velocity within its cavity is reliably measured by pulsed Doppler in a substantial fraction of patients. Contrast enhancement improves the feasibility and the accuracy of transthoracic evaluation of left atrial appendage flow velocity. The practical value of these results in predicting thromboembolic risk and success of cardioversion of atrial fibrillation needs to be proved by prospective studies.

Doppler echocardiography reliably predicts pulmonary artery wedge pressure in patients with chronic heart failure even when atrial fibrillation is present

BACKGROUND AND AIMS

In patients with chronic congestive heart failure a high pulmonary artery wedge pressure (PAWP) is associated with poor prognosis, severe symptoms and low exercise tolerance. When atrial fibrillation is present the non-invasive prediction of PAWP by Doppler echocardiography is generally considered to be not reliable.

METHODS

In 51 consecutive patients with chronic heart failure, due to either ischemic and non-ischemic dilated cardiomyopathy, and atrial fibrillation simultaneous Doppler echocardiographic and hemodynamic studies were used to estimate PAWP. The power of the obtained multivariate equation was compared with that of previously developed equations and was then prospectively tested in a group of 15 patients.

RESULTS

The deceleration rate (DR) of early diastolic mitral flow, the left ventricular iso-volumic relaxation time (IVRT) and the systolic fraction of pulmonary venous flow (SF) were independent predictors of PAWP and the following multivariable equation was derived: PAWP=24.04 + 1.23 x DR- 0.089 x IVRT - 0.175 x SF. The correlation between invasive PAWP and the PAWP non-invasively estimated by this equation in the testing group was 0.91 (standard error of estimate=3.2 mmHg). The mean difference was 0.93 and the standard error of differences was 2.7 mmHg.

CONCLUSION

In patients with chronic heart failure due to dilated cardiomyopathy who are in atrial fibrillation a relatively accurate estimation of PAWP can be obtained by Doppler echocardiography of mitral and pulmonary venous flow.

[Non-invasive evaluation of the hemodynamic profile in patients with heart failure: estimation of left atrial pressure]

The management of patients with heart failure requires an accurate and non-invasive estimation of left ventricular filling pressures. This is essential in order to optimize unloading treatment, interpret equivocal symptoms, assess disease severity (and prognosis), and follow up the hemodynamic effect of long-term treatments. Since Doppler technique was implemented, several non-invasive methods to estimate left ventricular filling pressures were developed. Among these, a method based on the calculation of the left ventricular-atrial pressure gradient and its subtraction from systolic arterial blood pressure can be used in patients with significant mitral regurgitation and well-defined continuous wave Doppler signal of the regurgitant flow. Mitral and pulmonary venous flow velocities, as assessed by pulsed Doppler, are closely related to left atrial pressures, and several derived indices can be used to qualitatively estimate left ventricular filling pressures in patients with heart failure due to left ventricular systolic dysfunction who are in sinus rhythm. Furthermore, the combination of these indices in multivariable equations can improve this relationship and allows for a quantitative estimation of filling pressures, even in patients with significant mitral regurgitation and atrial fibrillation. There are, however, several groups of patients with heart failure in whom pulsed Doppler of mitral and pulmonary venous flow provides limited hemodynamic information. These include those with a) sinus tachycardia and/or prolonged P-R interval; b) normal left ventricular systolic function (and "pure" diastolic heart failure); c) primarily abnormal left atrial dysfunction (such as patients who had undergone heart transplantation), and d) technically inadequate Doppler recordings of pulmonary venous flow. To assess left ventricular filling pressures in these patients, two new methods which combine pulsed Doppler mitral flow indices with load-independent indices of left ventricular relaxation (either early diastolic velocity of mitral annulus, as assessed by tissue Doppler, or propagation velocity of mitral inflow, as assessed by color M-mode) can be used.

Dobutamine stress echocardiography and thallium-201 SPECT for detecting ischaemic dilated cardiomyopathy in patients with heart failure

AIMS

A diagnosis of ischaemic aetiology of a dilated cardiomyopathy has important therapeutic and prognostic implications. In such patients, abnormal ECG and atypical symptoms limit the usefulness of standard ECG-ergometry in detecting myocardial ischaemia. To assess the values of high-dose dobutamine stress echocardiography and of Thallium-201 SPECT (exercise-reinjection-rest protocol) in differentiating between ischaemic and non-ischaemic dilated cardiomyopathy, 37 patients with suspected myocardial ischemia, low ventricular ejection fraction (23 +/- 5%) and heart failure were studied.

METHODS AND RESULTS

Coronary artery disease was defined as >50% coronary stenosis in at least one coronary artery. By dobutamine stress echocardiography, ischaemic dilated cardiomyopathy was considered present when either an ischaemic response (biphasic response or direct deterioration) or a scar (fixed dyssynergy) was documented in at least two segments. By Thallium-201 SPECT, severe perfusion defects, either reversible (ischaemia) or fixed (scar), in at least two segments were considered markers of ischaemic dilated cardiomyopathy. Twenty-three patients had ischaemic dilated cardiomyopathy, while 14 had normal coronary arteries. The presence of myocardial ischaemia and/or scar by dobutamine stress echocardiography identified patients with ischaemic dilated cardiomyopathy with a sensitivity of 100% and a specificity of 86%. The sensitivity of Thallium-201 SPECT was 92%, its specificity was 69%. Three of the four false positive results occurred in patients with left bundle branch block. Thirty-two patients were concordantly classified by the two techniques (agreement=86%, k=0.73).

CONCLUSION

Both dobutamine stress echocardiography and Thallium-201 SPECT are sensitive techniques for detecting the ischaemic aetiology of dilated cardiomyopathy. The specificity is lower, particularly by SPECT, when left ventricular branch block is present.

The bicaval anastomosis technique for orthotopic heart transplantation yields better atrial function than the standard technique: an echocardiographic automatic boundary detection study

BACKGROUND

Atrial function is an important determinant of cardiac performance. In patients who undergo operation by standard heart transplantation atrial enlargement, distortion of geometry and asynchronous contraction resulting from the donor/recipient atrial connections may affect atrial function. The bicaval anastomosis technique should be free from these limitations.

METHODS

We used the echocardiographic automatic boundary detection technique to obtain on-line time/volume curves of right and left atria from patients who had undergone bicaval (n = 22) or standard (n = 27) heart transplantation and from 15 control subjects. Maximal, middiastolic, preatrial contraction, and minimal volumes of both atria were measured. Reservoir volume (defined as the difference between maximal and middiastolic atrial volumes); pump volume (defined as the difference between preatrial contraction and minimal atrial volumes); and conduit volume (defined as the difference between left ventricular stroke volume and the sum of reservoir and pump volumes) were derived for both atria. Atrial emptying fraction was calculated as the difference between maximal and minimal volumes divided by the maximal volume and expressed in percent and pump fraction as the pump volume divided by the sum of reservoir and pump volumes. Tricuspid and mitral regurgitation, evaluated by color-flow Doppler scanning, were considered significant when they were greater than grade 1. Atrial ejection force was calculated from mitral and tricuspid flow velocities at atrial contraction.

RESULTS

In patients who had bicaval heart transplantation, both atria were smaller than in patients who underwent standard heart transplantation. With the bicaval technique right and left atrial emptying (right 45% +/- 9% vs 36% +/- 10%, p < .05; left 51% +/- 8% vs 39% +/- 8%, p < .001) and pump fractions (right 57% +/- 17% vs 19% +/- 13%, p < .001; left 45% +/- 28% vs 22% +/- 12%, p < .01) were greater than with the standard technique and similar to those in control subjects. Right atrial ejection force was significantly greater in bicaval (10.0 +/- 5.6 kdyne) than in standard heart transplantation (4.5 +/- 2.2 kdyne, p < .0001). Significant tricuspid or mitral regurgitation was rarely found in bicaval heart transplant recipients (3 and 1 of the 22 patients, respectively), although they were much more frequent after standard heart transplantation (13 and 8 of the 27 patients, respectively).

CONCLUSIONS

Heart transplantation performed with the bicaval anastomosis technique determines smaller atrial volumes, yields better right and left atrial function and fewer atrioventricular valve regurgitation than the standard technique.

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.

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.

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.

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.

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.

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.

[Pulmonary venous flow in patients with chronic heart failure: feasibility and additional value compared to transmitral flow for non-invasive estimation of pulmonary wedge pressure]

BACKGROUND

In many cardiac conditions, Doppler of transmitral flow has been showed to be related to left ventricular filling pressure, but several factors may limit its practical value in estimating pulmonary wedge pressure in patients with chronic heart failure. Pulmonary venous velocities directly depend on the oscillations of left atrial pressure. Recent studies suggest that transthoracic Doppler of pulmonary venous flow provides a more accurate estimation of pulmonary wedge pressure. However the relative values of transmitral and pulmonary venous flow for assessing pulmonary wedge pressure in patients with chronic heart failure have not been fully classified until now. Accordingly, we performed this study to assess the feasibility of transthoracic Doppler of pulmonary venous flow in patients with chronic heart failure and to evaluate whether it provides additional information regarding pulmonary wedge pressure when compared with Doppler indices of transmitral flow.

METHODS

Simultaneous Doppler echocardiographic examinations and right heart catheterizations were performed prospectively in 300 consecutive patients with chronic heart failure due to dilated cardiomyopathy. The correlations of mitral and pulmonary venous flow velocity variables, left atrial volumes, mitral regurgitation jet area and left ventricular ejection fraction with pulmonary artery wedge pressure were evaluated.

RESULTS

A complete recording of transthoracic pulmonary venous flow including all components was obtained in 66% of patients, while only systolic and diastolic forward flow were recorded in 88% of patients. Several indices, derived from pulmonary venous flow, were correlated with pulmonary wedge pressure; the strongest correlation was between systolic fraction of peak velocities and pulmonary wedge pressure (r = -0.76). This value was similar to that obtained between deceleration rate (r = 0.78) and deceleration time (r = -0.67) of transmitral flow and pulmonary wedge pressure. A systolic fraction > 40% showed a greater positive predictive value than restrictive pattern of transmitral flow for identifying patients with pulmonary wedge pressure > 18 mmHg (95% vs 86% p < 0.05). This accuracy is confirmed also in patients who had a single peak of transmitral flow.

CONCLUSIONS

Doppler of pulmonary venous flow can be performed in a high percentage of patients with chronic heart failure due to dilated cardiomyopathy. The indices derived from transthoracic pulmonary venous flow are strongly correlated with pulmonary wedge pressure and improve the noninvasive identification of patients with high pulmonary wedge pressure, even when transmitral flow pattern is difficult to be interpreted.

Mitral flow velocity changes after 6 months of optimized therapy provide important hemodynamic and prognostic information in patients with chronic heart failure

Transmitral flow velocity patterns evaluated by Doppler echocardiography provide important hemodynamic and prognostic information in various cardiac conditions. However, these patterns may change over time, and so far the hemodynamic and prognostic significance of these changes has not been established. Accordingly, we performed this study to determine the hemodynamic and prognostic value of changes in transmitral flow velocity patterns after 6 months of optimized medical treatment in patients with chronic heart failure due to ischemic or nonischemic dilated cardiomyopathy. Ninety-eight consecutive patients with chronic heart failure underwent a clinical examination, a cardiopulmonary exercise test, and simultaneous Doppler echocardiographic and hemodynamic studies at baseline and after 6 months, patients were followed up for 12 +/- 7 months. Cardiac death and heart transplantation while patients were in critical condition were considered events. A restrictive pattern was defined by an early-to-late peak diastolic velocity ratio > 1 and an early diastolic deceleration time < or = 130 msec. Patients were grouped according to their mitral flow pattern at baseline and its changes after chronic optimized therapy. No significant changes in clinical, ergometric, and hemodynamic variables were found after 6 months in the 49 patients who had a persistent restrictive transmitral flow pattern or the 24 patients who had a persistent nonrestrictive transmitral flow pattern. In the 19 patients who had a restrictive pattern at baseline that reverted into a nonrestrictive pattern, this change was accompanied by a highly significant reduction in pulmonary wedge pressure (from 25 +/- 7 mm Hg to 11 +/- 3 mm Hg) and by an increase in exercise capacity, whereas in the 6 patients who had a nonrestrictive pattern that became restrictive, hemodynamic features markedly deteriorated. Seventeen of the 21 events occurred in the 49 patients (event rate 35%) with a persistent restrictive pattern, whereas the event rate was much lower in the 19 patients with a reversible restrictive pattern (5%) and in the 24 patients with a persistent nonrestrictive pattern (4%). Two (33%) of the 6 patients in whom a restrictive pattern developed had events. Cox analysis revealed that a restrictive transmitral flow pattern (p = 0.0068) and peak rate of oxygen consumption (p = 0.0056) detected at the late examination were significantly related to cardiac events. These results show that in patients with chronic heart failure, changes in transmitral flow patterns after chronic optimized therapy are correlated with changes in pulmonary wedge pressure, are accompanied by changes in functional capacity, and provide relevant independent prognostic information.

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.

Systemic thromboembolism in chronic heart failure. A prospective study in 406 patients

In patients with heart failure the risk of systemic thrombo-embolism and the benefit of anticoagulation are uncertain. To assess the incidence of systemic thromboembolism and the factors associated with an increased risk, 406 consecutive patients with chronic heart failure were prospectively investigated. Their left ventricular ejection fraction was 23 +/- 8%, pulmonary wedge pressure 19 +/- 10 mmHg and cardiac index 2.3 +/- 1.41. min-1.m-2 of body surface area. Two hundred patients were in NYHA functional class III-IV. Two hundred and thirty-two patients were receiving oral anticoagulants. Over a follow-up period of 16 +/- 11 months, thromboembolism occurred in 11 patients (2.7%), seven of whom were on anticoagulants. Among clinical, echocardiographic and haemodynamic variables, atrial fibrillation, more severe haemodynamic impairment and low exercise capacity were associated with increased thromboembolic risk. No echocardiographic findings, including the presence of intracavitary thrombi, either at baseline or during follow-up, were related to subsequent thromboembolic events. The rate of embolism did not differ in patients receiving anticoagulants (4%) compared with those who did not receive anticoagulants (1%). No major bleeding occurred during follow-up. Thus, in patients with chronic heart failure and sinus rhythm the incidence of systemic thromboembolism is low regardless of anticoagulant treatment. Atrial fibrillation, particularly when associated with low cardiac index, identifies a subgroup of patients at high risk of events. In this subgroup, a moderate-intensity anticoagulant regimen provides unsatisfactory protection against thromboembolism.

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.

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.

Orthotopic heart transplantation with bicaval anastomosis

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Doppler evaluations of left ventricular diastolic filling and pulmonary wedge pressure provide similar prognostic information in patients with systolic dysfunction after myocardial infarction

Previous studies have demonstrated that in patients with various types of cardiac diseases and left ventricular dysfunction, left ventricular filling patterns assessed by Doppler of mitral flow are correlated to ventricular filling pressure, the prognostic value of which is well known. The current study was carried out to determine the prognostic importance of a noninvasive evaluation of left ventricular filling by Doppler of mitral flow in patients with systolic dysfunction after myocardial infarction and to compare its value with that of pulmonary wedge pressure. One hundred seven patients with a left ventricular ejection fraction < 40% were studied 3 to 12 weeks after myocardial infarction. All patients underwent a complete clinical examination, a standard two-dimensional and Doppler echocardiographic examination, and right-sided heart catheterization at rest and during a cardiopulmonary bicycle exercise test. Early and late diastolic peak flow velocities, their ratio, and the deceleration time of early diastolic velocity were measured from pulsed-wave Doppler of mitral flow. Follow-up data were obtained for 101 patients. During a mean period of 25 (median 21, range 12 to 60) months cardiac events (death, heart transplantation, or heart failure requiring hospitalization) occurred in 43 (42%) patients. Patients with cardiac events during follow-up were in a worse functional class and had a more impaired exercise capacity and higher capillary pulmonary wedge pressure at baseline examination. Among Doppler echocardiographic variables, in patients with cardiac events a greater early to late diastolic peak velocity ratio of mitral flow (1.9 +/- 0.9 pl/min vs 1.2 +/- 0.8 pl/min, p < 0.001) and a shorter early diastolic deceleration time (112 +/- 35 vs 145 +/- 42 msec, p < 0.001) were found. Cox analysis revealed that the combination of early to late diastolic peak flow velocity ratio of mitral flow and New York Heart Association functional class were the strongest noninvasive independent predictors of cardiac events. One-year event-free probability of survival was 90% in patients with an early to late diastolic peak velocity ratio < or = 1 (all but 1 in New York Heart Association functional class I or II) but was significantly less in patients with an early to late diastolic peak velocity ratio > 1 (64% in functional class I or II and 36% functional class III). Similar results were obtained when mean pulmonary wedge pressure was considered instead of the ratio between peak flow velocities of mitral flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Cardiac and vascular sources of peripheral thromboembolism in patients with atrial fibrillation. A combined transesophageal and vascular ultrasonographic study

Atrial fibrillation is associated with an increased risk of peripheral thromboembolism. Although emboli arising from the left atrium are the most probable causes of peripheral ischemic events, coexistent vascular mechanisms may play a role in the genesis of thromboembolism. To assess the prevalence and the relative role of cardiac and vascular sources of thromboembolism in patients with atrial fibrillation 101 consecutive patients with (group 1: 47 patients) and without (group 2: 54 patients) recent thromboembolism were studied by transesophageal echocardiography and ultrasound duplex scanning of carotid arteries. Left atrial thrombosis was found in 19 (40%) group 1 patients and in 3 (5%) group 2 patients. Left atrial thrombosis and/or spontaneous echocardiographic contrast were significantly more frequent in group 1 patients than in group 2 (70% vs 20%, p < 0.001). Stepwise regression analysis revealed that they were the only independent predictors of thromboembolism (p = 0.018, p = 0.0003 respectively). Among clinical and transthoracic echocardiographic variables, left atrial diameter (p = 0.022), rheumatic mitral stenosis (p = 0.0058) and absence of significant mitral regurgitation (p = 0.027) emerged as independent predictors of left atrial thrombosis and/or spontaneous echocardiographic contrast. When transesophageal parameters were also entered into the analysis, the only independent predictor was low blood flow velocity within the left atrial appendage (p = 0.0001). Vascular sources (obstructive carotid arteries plaques, non-obstructive ulcerated carotid plaques and thoracic aortic atherosclerotic debris) were found in 30.6% of patients. Their prevalence was not significantly different in the two groups (34% in group 1, 27% in group 2). Vascular and cardiac sources coexisted in 23% of patients with thromboembolism. Seven of the 10 patients with more severe vascular lesions (i.e., obstructive carotid artery lesions or pedunculated mobile aortic debris) were from group 1 and 5 of them had negative cardiac results. In conclusion, these results indicate that a cardioembolic mechanism due to blood stasis within the left atrium is involved in most of the atrial fibrillation-related thromboembolic events. In patients with atrial fibrillation vascular sources are not infrequent and may be involved in the genesis of ischemic events in some patients. Transesophageal echocardiography may be useful in identifying subgroups of patients with atrial fibrillation who are at high thromboembolic risk.

Reproducibility of Doppler indices of left ventricular systolic and diastolic function in patients with severe chronic heart failure

Doppler ultrasound has been utilized to evaluate cardiac output and left ventricular filling pressure in patients with various cardiac diseases. This method would be particularly useful for non-invasive haemodynamic monitoring in patients with severe chronic heart failure. However, few data exist on the reproducibility of Doppler indices in this population. To determine the magnitude of technical and biological variability of Doppler indices, serial Doppler echocardiographic studies were performed in 26 patients with severe heart failure in the usual clinical setting. Short-term intra- and inter-observer, mid-term and day-to-day variabilities of stroke volume, cardiac output, maximal early and late diastolic velocities of mitral flow, rate of decrease and deceleration time of flow velocity in early diastole and the colour Doppler area of the mitral regurgitant jet were evaluated by two cardiologists. For each source of variability, correlation coefficients with standard errors and mean differences between paired determinations with their standard deviations were calculated. Short-term (intra- and inter-observer) variability was small for each considered variable: the mean differences of measurements were within 10% of the mean value for most parameters and no systematic error was found. Stroke volume and cardiac output showed a significant increase in the afternoon. The standard deviations of differences between day-to-day measurements were 4.1 ml (9% of the mean value) and 39 ml (11% of the mean value), respectively. Doppler indices assessing diastolic filling and colour Doppler area of mitral regurgitant jet showed greater variations on a mid-term and day-to-day basis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Usefulness of ultrasonographic techniques in catheterization of the internal jugular vein in patients with chronic heart failure]

BACKGROUND

The right internal jugular vein as a route for right heart catheterization and continuous infusion of drugs is increasingly used in patients with heart failure. Although this approach has several advantages, a small but definite number of unsuccessful vein punctures and/or of complications have been reported. This prospective study was designed to evaluate the usefulness of ultrasound techniques for cannulating internal jugular vein in a series of 310 consecutive patients with chronic heart failure.

METHODS

In all patients a duplex scanning of internal jugular veins was performed before the cannulation. A subgroup of 62 patients was selected for having a "difficult" cannulation according to the following criteria: previous failure of cannulating the vein (3 unsuccessful needle advances); neck abnormalities; severe emphysema and respiratory insufficiency. In these patients a Doppler-guidance system, which consisted of a miniature ultrasound Doppler transducer inserted in a standard 19 gauge needle, was used. The needle was advanced under the skin following the maximal audio signal of the venous flow. The following variables were considered: success rate, number of needle advances to cannulate the vein, time elapsed from local anesthesia and the insertion of the catheter, minor and major complications.

RESULTS

Duplex scanning showed that in 14 patients (4.5%) the right internal jugular vein was occluded or severely narrowed. In all patients the left internal jugular vein, which showed a compensatory dilatation, was successfully cannulated. In 294 of the remaining 296 patients the position of the vein was anterior to the carotid artery at a depth of 4-27 mm below the skin. With respect of the triangle formed by the two heads of the sternocleidomastoid muscle, the vein was central in 35%, medial in 15% and lateral in 60% of cases. Based on duplex scanning ultrasound data, 285 patients underwent internal jugular vein cannulation, which was achieved at the first attempt in 74% and within 3 attempts in 87% of cases. Minor and major complications occurred in 4 (1.4%) and in 1 (0.3%) respectively. By the Doppler guidance system, the cannulation was successfully achieved in 79% of patients at the first attempt and in 98% of patients (61/62) within 3 attempts. In one patient an uneventful puncture of the carotid artery occurred. The time to perform the cannulation was not significantly different using the two approaches (conventional approach: 4.4 +/- 3 minutes; Doppler guidance system: 4.2 +/- 2). Overall the internal jugular vein was successfully cannulated in 307/310 patients (99%).

CONCLUSIONS

Ultrasound techniques provide useful information which facilitates the cannulation of the internal jugular vein in patients with heart failure. The Doppler guidance method allows a rapid and safe cannulation of the vein even in cases that are difficult using the conventional approach.

[Heart failure unit: 1 year experience]

Many factors such as aging and pharmacologic and surgical progress contribute to the growing of organizational problems of health care for patients with severe chronic heart failure. Since March 16, 1992, in the Medical Center of Montescano, an experimental model (Heart Failure Unit) of health assistance has been in development, taking into account the assistance and observational needs of such patients. During the first year of activity, 173 patients were treated in the Unit, for a total of 307 admissions. In-hospital complications were 5 deaths, 91 severe heart decompensations, 25 severe ventricular tachyarrhythmias, 17 infections, 11 severe bradyarrhythmias, 6 instances of acute heart failure due to atrial arrhythmias, 5 unstable angina episodes, 3 thromboembolisms, and 3 neuropsychiatric disorders. During the follow-up until August 15, 1993, 27 patients died and 19 underwent heart transplantation. Our experience focused on realizing the following goals: 1) to organize a fit hospital environment and adequate nursing; 2) to pursue the autonomy and independence of the patients; 3) to routinely cooperate in a multidisciplinary team; 4) to offer continuity of care to patients.

[Skeletal and respiratory muscle strength in chronic heart failure]

BACKGROUND

The aim of this study was to investigate limb and respiratory muscle strength in chronic heart failure (CHF).

METHODS

Our study population consisted of 45 male CHF patients, 25 in NYHA Class II and 20 in NYHA Class III, and 22 male post-MI patients without left ventricular dysfunction (LVEF > 50%). All patients underwent assessment of respiratory muscle strength by maximal inspiratory (MIP) and expiratory (MEP) pressures, of handgrip force and peak torque developed during isokinetic Knee extension (EX) (quadriceps) and flexion (hamstring) at 120 degrees/sec.

RESULTS

CHF patients showed a significant decrease in all limb and respiratory muscle strength compared to control patients. Moreover, NYHA Class III patients showed significantly reduced values of MIP, handgrip, and EX forces, as well as significantly reduced exercise tolerance in terms of METS (2.8 +/- 0.9 vs 4.4 +/- 1.2, p < .05) and anaerobic threshold level (9.4 +/- 3 vs 12.8 +/- 1.7 mlO2/Kg, p < .05), as compared to those patients in NYHA Class II, while no significant differences were observed in LVEF, cardiac index and pulmonary capillary wedge pressures. Weak, but significant (p < .05) were the correlations between limb muscle and respiratory muscle strength. No correlations were found between muscle force and hemodynamic parameters. Significant correlations (from p < .05 to p < .0001) were found among exercise tolerance and limb muscle strength, but not between exercise tolerance and respiratory muscle strength. In summary: 1) respiratory and skeletal muscle strength is impaired in CHF; 2) respiratory and limb muscle strength reductions are partially related to each other; 3) the degree of central hemodynamic impairment is not correlated with muscle force. Deconditioning could be a major determinant of skeletal but not respiratory muscle weakness. Other factors link limb and respiratory weakness in CHF.

Left ventricular filling pattern and pulmonary wedge pressure are closely related in patients with recent anterior myocardial infarction and left ventricular dysfunction

To determine whether mitral flow velocity can be used to estimate mean pulmonary wedge pressure (PWP) in patients with left ventricular dysfunction, 50 patients with recent Q-wave anterior infarction and a reduced ejection fraction (less than 40%) underwent simultaneous pulsed-wave Doppler measurements of mitral flow and right heart catheterization. Doppler tracings and PWP were recorded at rest, after passive leg lifting (45 degrees) and (in 15 patients with increased PWP) after 5 mg sublingual ISDN. Significant correlations were found between the ratio of peak early to peak late diastolic velocity (E/A) and PWP (r = 0.83). Early diastolic deceleration and the ratio of the time velocity integral of atrial contribution to the total time velocity integral were also correlated to PWP (r = 0.80 and r = 0.79 (respectively). The E/A ratio was less than 1 in 25 patients and more than 1 in the remaining 25. An E/A ratio of at least 1 predicted a PWP of more than 20 mmHg with a sensitivity of 100% and a specificity of 86%. In all five patients, in whom the PWP was less than 20 mmHg at baseline and became greater with leg lifting, the E/A ratio changed from less than 1 to more than 1. After ISDN, changes in E/A ratio from more than 1 to less than 1 identified all 12 patients with a PWP falling below 20 mmHg. In conclusion, patients with recent Q-wave anterior infarction and a reduced ejection fraction mitral flow velocity-derived variables correlate with PWP representing a reliable index for the diagnosis of markedly increased PWP.(ABSTRACT TRUNCATED AT 250 WORDS)

Left atrial appendage dysfunction: a cause of thrombosis? Evidence by transesophageal echocardiography-Doppler studies

The blood flow velocity patterns within the left atrial appendage were studied by transesophageal color flow imaging and pulsed Doppler in 84 patients. At the time of the study, 57 of the patients were in sinus rhythm, 25 were in atrial fibrillation, and two were in atrial flutter. The relationships between atrial rhythm, blood flow pattern and the presence/absence of spontaneous echocardiographic contrast or thrombus within the appendage were investigated. Transesophageal echocardiography allowed recording of blood flow velocities in 81 of the 84 patients studied. In 51 of the 55 patients in sinus rhythm the pulsed Doppler study showed a biphasic blood flow pattern, whereas a multiphasic pattern was found in the two patients with atrial flutter and in 14 patients with atrial fibrillation. In four patients with sinus rhythm and 10 patients with atrial fibrillation, no significant blood flow velocity could be detected. Thrombus or spontaneous echocardiographic contrast were found within the left atrial appendage in 20 patients, and in all these patients blood flow was either absent or significantly reduced. Our findings indicate that an absent or low blood flow velocity within the left atrial appendage represents a predisposing factor for thrombosis. Isolated left atrial appendage dysfunction has been documented in four patients during sinus rhythm, which may lead to thrombosis. This observation may offer an explanation for cardioembolic events that occur occasionally in patients without apparent heart disease and sinus rhythm.

[Echocardiographic assessment of segmental kinetic changes of the left ventricle during ischemic attacks induced by slow hyperventilation]

The detection of stress-induced wall motion abnormalities by means of 2D Echo represents a reliable marker of ischemia. Few reports about two-dimensional echocardiography and provocative tests in patients suffering from primary angina are available in the literature. Twenty patients with electrocardiographically documented ischemic transitory attacks at rest underwent hyperventilation test 2-15 days after a spontaneous episode. A new wall motion abnormality and/or a worsening of an asynergy already present at rest occurred in ten patients; eight of them also showed diagnostic ECG changes. Wall motion abnormalities arose significantly earlier (from the end of hyperventilation: 1.7 +/- .84 vs 2.16 +/- 1.15 min, p less than .05). Three patients had angina, which, in all patients started after echocardiographic and ECG changes. All patients experienced paresthesia, and two patients tinnitus due to blood alkalosis. No clinical adverse reaction resulted from the test. Only one patient had ventricular arrhythmias in the recovery phase of the ischemia.

IN CONCLUSION

As concerns hyperventilation test, echocardiography has proven useful in identifying myocardial ischemia, comparable to electrocardiography. Moreover, in this study some patients had echocardiographic but not electrocardiographic changes as ischemic manifestations. Events after induction of ischemia with hyperventilation seem to follow the same sequence already observed in spontaneous attacks.

Pulsed Doppler evaluation of left ventricular filling in subjects with pathologic and physiologic third heart sound

Haemodynamic studies suggest that the rapid deceleration of left ventricular inflow at the end of early diastole may play an important role in the genesis of the third heart sound (S3). To confirm this hypothesis noninvasively, pulsed Doppler of transmitral flow was used. Mitral flow velocity wave was recorded in 20 post-infarction patients with audible S3 (Group 1), in 20 young healthy individuals with physiologic S3 (Group II), in 20 postinfarction patients without S3 (Group III) and in 20 normal adults (Group IV). Peak flow velocity in early diastole (Ev), peak flow velocity during atrial systole (Av), the Ev/Av ratio, the deceleration of early diastolic flow (EF slope), the ratio of the time velocity integral of early diastole to the total time velocity integral (TVle/TVlt) and the isovolumic relaxation time (IVRT) were measured from Doppler recordings. The time relation between S3, the mitral valve motion on M-mode tracing, and the mitral flow velocity wave were analysed comparing the intervals from the second sound to Ev (A2-Ev), to the E point of mitral valve motion (A2-Em) and to the S3 (A2-S3). In groups I and II Ev/Av ratio was higher (respectively 4.4 +/- 2.2 and 2.8 +/- 1.1) than in group III (0.8 +/- 0.4) and IV (1.3 +/- 0.3). Similar results were found for the TVle/TVlt ratio. In both groups with S3, EF slope was significantly steeper (respectively 9 +/- 1.8 and 7.5 +/- 1.1 m s) than in normal adults (4.4 +/- 1.1 m s) and patients without S3 (3.6 +/- 1.1 m s).(ABSTRACT TRUNCATED AT 250 WORDS)