Indications and practical approach to non-invasive ventilation in acute heart failure

In acute heart failure (AHF) syndromes significant respiratory failure (RF) is essentially seen in patients with acute cardiogenic pulmonary oedema (ACPE) or cardiogenic shock (CS). Non-invasive ventilation (NIV), the application of positive intrathoracic pressure through an interface, has shown to be useful in the treatment of moderate to severe RF in several scenarios. There are two main modalities of NIV: continuous positive airway pressure (CPAP) and pressure support ventilation (NIPSV) with positive end expiratory pressure. Appropriate equipment and experience is needed for NIPSV, whereas CPAP may be administered without a ventilator, not requiring special training. Both modalities have shown to be effective in ACPE, by a reduction of respiratory distress and the endotracheal intubation rate compared to conventional oxygen therapy, but the impact on mortality is less conclusive. Non-invasive ventilation is also indicated in patients with AHF associated to pulmonary disease and may be considered, after haemodynamic stabilization, in some patients with CS. There are no differences in the outcomes in the studies comparing both techniques, but CPAP is a simpler technique that may be preferred in low-equipped areas like the pre-hospital setting, while NIPSV may be preferable in patients with significant hypercapnia. The new modality 'high-flow nasal cannula' seems promising in cases of AHF with less severe RF. The correct selection of patients and interfaces, early application of the technique, the achievement of a good synchrony between patients and the ventilator avoiding excessive leakage, close monitoring, proactive management, and in some cases mild sedation, may warrant the success of the technique

Abnormal shortened diastolic time length at increasing heart rates in patients with abnormal exercise-induced increase in pulmonary artery pressure

<p>Abstract</p> <p>Background</p> <p>The degree of pulmonary hypertension is not independently related to the severity of left ventricular systolic dysfunction but is frequently associated with diastolic filling abnormalities. The aim of this study was to assess diastolic times at increasing heart rates in normal and in patients with and without abnormal exercise-induced increase in pulmonary artery pressure (PASP). Methods. We enrolled 109 patients (78 males, age 62 ± 13 years) referred for exercise stress echocardiography and 16 controls. The PASP was derived from the tricuspid Doppler tracing. A cut-off value of PASP ≥ 50 mmHg at peak stress was considered as indicative of abnormal increase in PASP. Diastolic times and the diastolic/systolic time ratio were recorded by a precordial cutaneous force sensor based on a linear accelerometer.</p> <p>Results</p> <p>At baseline, PASP was 30 ± 5 mmHg in patients and 25 ± 4 in controls. At peak stress the PASP was normal in 95 patients (Group 1); 14 patients (Group 2) showed an abnormal increase in PASP (from 35 ± 4 to 62 ± 12 mmHg; P < 0.01). At 100 bpm, an abnormal (< 1) diastolic/systolic time ratio was found in 0/16 (0%) controls, in 12/93 (13%) Group 1 and 7/14 (50%) Group 2 patients (p < 0.05 between groups).</p> <p>Conclusion</p> <p>The first and second heart sound vibrations non-invasively monitored by a force sensor are useful for continuously assessing diastolic time during exercise. Exercise-induced abnormal PASP was associated with reduced diastolic time at heart rates beyond 100 beats per minute.</p

WEB downloadable software for training in cardiovascular hemodynamics in the (3-D) stress echo lab

When a physiological (exercise) stress echo is scheduled, interest focuses on wall motion segmental contraction abnormalities to diagnose ischemic response to stress, and on left ventricular ejection fraction to assess contractile reserve. Echocardiographic evaluation of volumes (plus standard assessment of heart rate and blood pressure) is ideally suited for the quantitative and accurate calculation of a set of parameters allowing a complete characterization of cardiovascular hemodynamics (including cardiac output and systemic vascular resistance), left ventricular elastance (mirroring left ventricular contractility, theoretically independent of preload and afterload changes heavily affecting the ejection fraction), arterial elastance, ventricular arterial coupling (a central determinant of net cardiovascular performance in normal and pathological conditions), and diastolic function (through the diastolic mean filling rate). All these parameters were previously inaccessible, inaccurate or labor-intensive and now become, at least in principle, available in the stress echocardiography laboratory since all of them need an accurate estimation of left ventricular volumes and stroke volume, easily derived from 3 D echo

Preejection period as a sympathetic activity index: a role of confounding factors

In previous studies, one of the systolic time intervals - preejection period (PEP) - was used as an index of sympathetic activity reflecting the cardiac contractility. However, PEP could be also influenced by several other cardiovascular variables including preload, afterload and diastolic blood pressure (DBP). The aim of this study was to assess the behavior of the PEP together with other potentially confounding cardiovascular system characteristics in healthy humans during mental and orthostatic stress (head-up tilt test - HUT). Forty-nine healthy volunteers (28 females, 21 males, mean age 18.6 years (SD=1.8 years)) participated in the study. We recorded finger arterial blood pressure by volume-clamp method (Finometer Pro, FMS, Netherlands), PEP, thoracic fluid content (TFC) - a measure of preload, and cardiac output (CO) by impedance cardiography (CardioScreen (R) 2000, Medis, Germany). Systemic vascular resistance (SVR) - a measure of afterload - was calculated as a ratio of mean arterial pressure and CO. We observed that during HUT, an expected decrease in TFC was accompanied by an increase of PEP, an increase of SVR and no significant change in DBP. During mental stress, we observed a decrease of PEP and an increase of TFC, SVR and DBP. Correlating a change in assessed measures (delta values) between mental stress and previous supine rest, we found that Delta PEP correlated negatively with Delta CO and positively with Delta SVR. In orthostasis, no significant correlation between Delta PEP and Delta DBP, Delta TFC, Delta CO, Delta MBP or Delta SVR was found. We conclude that despite an expected increase of sympathetic activity during both challenges, PEP behaved differently indicating an effect of other confounding factors. To interpret PEP values properly, we recommend simultaneously to measure other variables influencing this cardiovascular measure.Web of Science66suppl. 2S275S26

Study of the resonant behaviour of bubbles embbeded in gelatin

Many diseases present abnormally high pressures at different points of the circulatory system, such as inside the heart, the portal vein or the pulmonary artery. For this reason, physicians need to know the pressure at these specific points either to help diagnosis or to monitor the evolution of a patient’s condition. Nowadays, these pressure measurements are performed invasively, for instance by navigating a catheter with a pressure sensor at its tip to the point of interest. As any invasive procedure, acquiring these measurements presents a number of shortcomings that medical doctors would like to avoid. Consequently, providing physicians with a non-invasive pressure measurement technique would represent a great advance in the diagnosis and/or treatment of these patients. Ultrasound Contrast Agents (UCAs), microbubbles injected into the blood stream to aid ultrasonic imaging, offer the possibility of obtaining the blood pressure at localized points of the circulatory system in non-invasive ways. Indeed, it can be shown mathematically how these microbubbles oscillate at a characteristic frequency (resonance frequency) when insonated with a pressure pulse with the appropriate features. More interestingly, it can also be shown that this resonant frequency depends on the ambient pressure at the bubble’s location. With these ideas in mind, in this thesis we have conducted an experimental and numerical investigation aimed at measuring how the resonance frequency of bubbles immersed in gelatin depends on the ambient pressure. Since the focus of this work is on the Physics, rather than on implementing a practical technique, we have worked with millimetric bubbles (commercial UCAs are micrometric) in order to overcome a number of experimental problems associated with using very small bubbles. Furthermore, fixing the bubbles in gelatin also allows for a prolonged observation and thus facilitates the experiments. But at the same time, gelatin constitutes a very realistic model of the rheological properties of the soft tissue that would surround bubbles in some real medical applications (think, for instance, of a bubble circulating through a narrow capillary surrounded by soft tissue). In our experiments, bubbles are insonated with chirps: pressure pulses that sweep a range of frequencies that contains the resonance one. Then, the radius vs. time evolution of the bubbles is obtained by applying digital image processing techniques to high-speed movies acquired synchronously with the acoustic insonation. Finally, the time evolutions of the bubble radii are processed using wavelets to extract the main frequency at which they oscillate. Although the experimental procedure designed and implemented in this thesis detects that bubbles oscillate at a well-defined frequency close to the expected resonance ones, our numerical simulations and the analysis of the pressure signals reveal that this frequency is actually arising from an improper behavior of the piezoelectric transducer used to generate the pulses. Finally, we point out future lines in which this work could be improved, most notably replacing the transducer by another one that performs better in the range of frequencies of interest. This solution is being implemented at the time of writing this dissertation.Ingeniería Mecánic

Echocardiographic Assessment of Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia: Systematic Review of Literature and a Proposed Algorithm for Assessment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111176/1/echo12738.pd

The Adult Patient with Eisenmenger Syndrome: A Medical Update After Dana Point Part I: Epidemiology, Clinical Aspects and Diagnostic Options

Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death

Tissue Doppler assessment of right ventricular function in female patients with limited form of systemic sclerosis

AbstractBackgroundCardiac involvement in systemic sclerosis (SSc) is often clinically occult. The aim of this study was the evaluation of early subclinical right ventricular (RV) involvement in patients with limited form of systemic sclerosis by tissue Doppler.MethodsTwenty female patients with limited cutaneous SSc and 20 control female subjects, matched for age were studied with transthoracic echocardiography and tissue Doppler imaging (TDI) to assess RV function. Patients with pulmonary hypertension, chronic renal failure, diabetes mellitus, hypertension, heart failure, left ventricular hypertrophy, ischemic or rheumatic heart disease were excluded.ResultsPatients with limited form SSc had significant lower tricuspid annulus peak systolic velocities (ST) (9.95±1.78 vs. 11.05±1.53cm/s, p<0.044), early (ET) (9.65±1.30 vs. 12.50±1.23cm/s, p<0.0001), late (AT) diastolic velocity (12.60±2.01 vs. 18.15±1.81cm/s, p<0.0001), and tricuspid annular plane systolic excursion (TAPSE) (23.05±3.50 vs. 26.50±1.90, p<0.001) compared to controls. Myocardial performance index (MPI) of the RV was higher in SSc patients compared to controls (0.41±0.05 vs. 0.30±0.02, p<0.0001). There were significant correlations between disease duration and ST and RV MPI (r=−0.883, p<0.0001; r=0.686, p<0.001, respectively).ConclusionsPatients with limited form of SSc present with pulsed-tissue Doppler imaging indices indicative of right ventricle dysfunction, which had significant correlations with disease duration. Tissue Doppler is a valuable non-invasive tool for detecting RV myocardial involvement in patients with limited SSc