Noninvasive methods for detecting elevated left-sided cardiac filling pressure

A finger photoplethysmography waveform during the valsalva maneuver detects changes in left heart filling pressure after hemodialysis

Background

A noninvasive system for determining left ventricular (LV) filling pressure may help to improve personalized fluid removal goals in hemodialysis patients. We previously showed that the change in photoplethysmography (PPG) pulse amplitude measured by finger PPG during a Valsalva maneuver correlates with invasively measured left ventricular end-diastolic pressure (LVEDP). This key PPG change, the ratio of finger PPG pulse amplitude at end-Valsalva to baseline, is known as the Pulse Amplitude Ratio, PAR. The objective of this study was to determine how PAR changes after fluid removal in hemodialysis.

Methods

We tested subjects with end-stage renal disease, before and after hemodialysis. Each subject performed a Valsalva maneuver with an effort of 20 mmHg for 10 s, guided by the device display. Finger PPG was recorded continuously before and during the maneuver. PAR was calculated automatically.

Results

Twenty-seven subjects (21 Males) ages 25–75 years were tested. Access sites were AV-fistulas of the arm predominantly. Weight decreased from 99.7 ± 36.9 kg to 97.0 ± 36.0 kg (p < 0.0003) with an average fluid removal of 3.07 ± 1.08 l. Correspondingly, PAR decreased from 0.74 ± 0.24 to 0.62 ± 0.23 (p = 0.003). The change in PAR was correlated with baseline PAR (r = 0.48, p = 0.01).

Conclusion

An index of left heart filling pressure obtained noninvasively using finger photoplethysmography during the Valsalva maneuver is sensitive enough to detect reductions in filling pressure after fluid removal with hemodialysis. Further studies are warranted to determine if this method can be used to guide fluid removal during hemodialysis.

Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre)

OBJECTIVE

Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre).

METHODS

Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s).

RESULTS

Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization.

CONCLUSION

Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution.

ADVANCES IN KNOWLEDGE

Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised.

Finger photoplethysmography during the Valsalva maneuver reflects left ventricular filling pressure

It is often challenging to assess cardiac filling pressure clinically. An improved system for detecting or ruling out elevated cardiac filling pressure may help reduce hospitalizations for heart failure. The blood pressure response to the Valsalva maneuver reflects left heart filling pressure, but its underuse clinically may be due in part to lack of continuous blood pressure recording along with lack of standardization of expiratory effort. In this study, we tested whether Valsalva-induced changes in the pulse amplitude of finger photoplethysmography (PPG), a technology already widely available in medical settings, correlate with invasively measured left ventricular end-diastolic pressure (LVEDP). We tested 33 subjects before clinically scheduled cardiac catheterizations. A finger photoplethysmography waveform was recorded during a Valsalva effort of 20 mmHg expiratory pressure sustained for 10 s, an effort most patients can achieve. Pulse amplitude ratio (PAR) was calculated as the PPG waveform amplitude just before release of expiratory effort divided by the waveform amplitude at baseline. PAR was well correlated with LVEDP (r = 0.68; P < 0.0001). For identifying LVEDP > 15 mmHG, PAR > 0.4 was 85% sensitive [95% confidence interval (95CI): 54-97%] and 80% specific (95CI: 56-93%). In conclusion, finger PPG, a technology already ubiquitous in medical centers, may be useful for assessing clinically meaningful categories of left heart filling pressure, using simple analysis of the waveform after a Valsalva maneuver effort that most patients can achieve.

IMPLANTABLE SENSORS TO ASSESS CARDIAC FUNCTION

The quest to discover effective methodologies to monitor the course of disease and response to therapeutic agents in patients with chronic heart failure continues. Clinical trials of specific therapeutic agents have shown efficacy in large groups of patients, but the outcome even with the most effective agents is recognized to be heterogeneous for largely unexplained reasons. The idea that the treatment of individual patients with heart failure could be guided by serial measurements of surrogate end points for mortality and morbidity remains attractive to clinicians. A new approach for clinicians is the guiding of heart failure care by hemodynamic implantable sensors, and in this paper, a brief review of the implantable technologies available to assess cardiac function for monitoring the course of chronic heart failure (CHF) is presented. Early results suggest that measurements arising from these implantable devices should help in guiding the long-term management of CHF patients. Careful consideration of measurements to make, end points to assess, and therapy in control patients will be essential in validating new approaches.

Handcarried echocardiography to assess hemodynamics in acute decompensated heart failure

Heart failure is a major source of cardiovascular morbidity, including acute decompensations requiring hospitalization. Because most therapeutic interventions in acute heart failure target optimization of cardiac output and volume status, accurate assessment of these parameters at the point of care is critical to guide management. However, physician bedside assessments of left ventricular (LV) function and volume status have limited accuracy. Traditional echocardiographic platforms, while useful for assessing ventricular and valvular function and volume status, have limitations for bedside use or frequent serial evaluation. Handcarried cardiac ultrasound devices, with their substantially lower costs, portability, and ease of use, circumvent many of the limitations of traditional echocardiographic platforms. The diagnostic capabilities of handcarried devices provide the opportunity for ultrasound assessment of LV function and serial bedside evaluation of volume status in patients with acutely decompensated heart failure.

Detection of elevated right atrial pressure using a simple bedside ultrasound measure

AIMS

Accurate assessment of right atrial pressure (RAP) often requires invasive measurement. With normal RAP, Valsalva increases right internal jugular vein (RIJV) cross sectional area (CSA) 20% to 30%. With high RAP, when venous compliance is low, we hypothesized that the increase in CSA would be blunted and could be detected non-invasively with bedside ultrasound.

METHODS AND RESULTS

RIJV ultrasound images were obtained in 67 patients undergoing right heart catheterization. The median RAP at end-expiration was 7 mm Hg (interquartile range [IQR] 5-9 mm Hg) in patients with normal RAP (n = 47) versus 15 mm Hg (IQR 12-22 mm Hg) in patients with elevated RAP (n = 20). With Valsalva, the median percent change in RIJV CSA was 35% (IQR 19%-79%) versus 5% (IQR 3%-14%) for normal and high RAP, respectively. By receiver operating curve analysis, a <17% increase in RIJV CSA with Valsalva predicted elevated RAP (> or =12 mmHg) with 90% sensitivity, 74% specificity, 94% negative predictive value, and 60% positive predictive value (area under the curve 0.86, P < .001).

CONCLUSIONS

An increase in RIJV CSA >17% during Valsalva effectively rules out elevated RAP. This simple bedside technique may be useful to assess central venous pressure and reduce the need for invasive pressure measurement.

Handheld echocardiography offers rapid assessment of clinical volume status

BACKGROUND

Assessment of volume status is vital for successful management of patients in heart failure (HF) programs. Bedside determination of elevated left-sided filling pressure (LFP) can be challenging and frequently inaccurate; therefore, incorporating technology such as handheld echocardiography, to aid in estimation of LFP, may improve patient care. In this study, we evaluated the feasibility and accuracy of handheld echocardiography by a nonexpert for potential use in the point of care evaluation of compensation.

METHODS

Subjects were recruited from the HF clinic or inpatient service at a single center. Each subject underwent a focused handheld transthoracic echocardiogram by a medical resident trained for 10 hours. Subjects were assigned to 1 of 4 filling patterns (1 = normal, 2 = abnormal relaxation, 3 = pseudonormal, 4 = restrictive) based on measurements by pulsed wave and tissue Doppler. A 3-step echocardiography test for congestion in HF (TEC-HF) was devised for estimation of LFP. The gold standard for determining elevated LFP was clinical evaluation by a HF specialist, who classified subjects as being euvolemic or hypervolemic.

RESULTS

A total of 100 consecutive subjects (72% male) were recruited, with average age of 60 years and left ventricular ejection fraction of 27%. All subjects had evaluable echocardiographic data. Based on TEC-HF, filling patterns 3 and 4 predicted hypervolemia and patterns 1 and 2 predicted euvolemia, with sensitivity and specificity of 86% and 92%, respectively, and positive and negative predictive values of 86% and 92%, respectively.

CONCLUSIONS

Applying TEC-HF with handheld echocardiography accurately reflects clinical LFP as assessed by HF specialists. This procedure was easily taught to nonexpert medical staff who obtained adequate images in all patients. Handheld echocardiography could be a useful tool for assessing volume status in nonspecialized community settings.

Aberrant central nervous system responses to the Valsalva maneuver in heart failure

Heart failure (HF) is associated with aberrant autonomic nervous system (ANS) activity, with altered responses to blood pressure and breathing challenges that appear to reflect abnormal central nervous system function. The authors used functional magnetic resonance imaging (fMRI) to determine whether the Valsalva maneuver, an ANS challenge, would show abnormal responses in ANS regulatory areas of the brain in HF. Brain fMRI signal changes in 5 HF patients (left ventricular ejection fraction, 0.15+/-0.08; age, 50+/-10 years) and 14 controls (age, 47+/-11 years) were assessed during 3 successive Valsalva maneuvers. The hypothalamus, hippocampus, putamen, amygdala, mid-cingulate, right insula, and cerebellar cortex showed exaggerated and phase-shifted fMRI responses in HF; other areas showed inverted signals from those found in controls. Central ANS control areas have altered phase, extent, and direction of responses to Valsalva maneuvers in a small sample of HF patients. These findings suggest that therapeutics that address neuroprotective aspects may be useful interventions for the condition.

Right heart catheterization and risk stratification in advanced heart failure

Right heart catheterization (RHC) has remained the gold standard in diagnosing elevated cardiac filling pressures. Despite advances in medical therapy, patients with persistent volume overload and heart failure (HF) have a poor prognosis. The diagnosis of volume overload can be difficult in advanced HF with clinical symptoms and signs often lacking sensitivity and specificity. Hemodynamic measurements at rest, especially pulmonary capillary wedge pressure and change in pulmonary capillary wedge pressure, have been closely linked to prognosis. However, RHC is invasive with attendant risks of complications. Noninvasive models without using catheterization-derived values have been shown to be equally predictive of survival. In selected clinical situations, especially the cardiorenal syndrome, RHC continues to play an important role. Newer invasive and noninvasive techniques to assess volume status are available, but large prospective trials are lacking. The advantage with continuous hemodynamic monitoring could be the development of an early warning system prior to the onset of symptomatic decompensation.

The Valsalva maneuver: a bedside "biomarker" for heart failure

Accurate assessment of volume status remains an important clinical goal in the management of patients with heart failure. Although physical examination can provide clues to volume status, its sensitivity and reproducibility are limited. Other noninvasive methods, such as measurement of natriuretic peptides or the use of impedance cardiography, are not well validated. The cardiovascular response to the Valsalva maneuver had been proposed as a simple, inexpensive bedside test for estimating filling pressures in patients with heart failure. Our objective was to summarize and critically evaluate the evidence for the use of the Valsalva maneuver in evaluating volume status in patients with heart failure. Studies have demonstrated a significant correlation between the cardiovascular response to the Valsalva maneuver and invasively measured ventricular filling pressures in patients with clinical heart failure. Although often overlooked in clinical training and practice, the cardiovascular response to the Valsalva maneuver is a potentially useful, noninvasive means of evaluating filling pressures in patients with heart failure.

Contrast-enhanced Doppler hemodynamics for noninvasive assessment of patients with chronic heart failure and left ventricular systolic dysfunction

We sought to evaluate whether contrast-enhanced Doppler echocardiography can improve the noninvasive estimation of hemodynamic variables in left ventricular (LV) dysfunction. Right-heart catheterization and Doppler echocardiography were simultaneously performed in 45 patients with LV dysfunction (ejection fraction: 29 +/- 7%) in sinus rhythm. Noninvasive variables were estimated as follows: cardiac output by pulsed Doppler of LV outflow tract; pulmonary capillary wedge pressure by a regression equation including mitral and pulmonary venous flow variables; pulmonary artery mean pressure from the calculated systolic and diastolic pulmonary artery pressures; and pulmonary vascular resistance from the previous measurements according to hemodynamic definition. Contrast enhancement increased the feasibility of pulmonary capillary wedge pressure estimation from 60% to 100%; of pulmonary artery mean pressure from 42% to 91%; and of pulmonary vascular resistance from 42% to 91%. Strong correlations between invasive and noninvasive hemodynamic variables were found: r = 0.90, standard error of the estimate (SEE) 0.45 L/min for cardiac output; r = 0.90, SEE 3.1 mm Hg for pulmonary capillary wedge pressure; r = 0.93, SEE 3.7 mm Hg for pulmonary artery mean pressure; and r = 0.85 SEE 1.0 Wood units for pulmonary vascular resistance. Weaker correlations for PAMP (r = 0.82, SEE 5.6 mm Hg) and PVR (r = 0.66, SEE 1.7 Wood units) were apparent prior to contrast enhancement. When patients were separated according to PVR threshold values, the contrast allowed the correct placement of 88% of patients, whereas only 57% were correctly assigned without it. The contrast increased accuracy and reduced interobserver variability in the evaluation of hemodynamic variables. The contrast-enhanced study is capable of increasing the value of noninvasive hemodynamic assessment in LV dysfunction.