Simultaneous measurement of pulmonary venous flow by intravascular catheter Doppler velocimetry and transesophageal Doppler echocardiography: relation to left atrial pressure and left atrial and left ventricular function

The assessment of left ventricular diastolic function: guidance and recommendations from the British Society of Echocardiography

Impairment of left ventricular (LV) diastolic function is common amongst those with left heart disease and is associated with significant morbidity. Given that, in simple terms, the ventricle can only eject the volume with which it fills and that approximately one half of hospitalisations for heart failure (HF) are in those with normal/'preserved' left ventricular ejection fraction (HFpEF) (Bianco et al. in JACC Cardiovasc Imaging. 13:258-271, 2020. 10.1016/j.jcmg.2018.12.035), where abnormalities of ventricular filling are the cause of symptoms, it is clear that the assessment of left ventricular diastolic function (LVDF) is crucial for understanding global cardiac function and for identifying the wider effects of disease processes. Invasive methods of measuring LV relaxation and filling pressures are considered the gold-standard for investigating diastolic function. However, the high temporal resolution of trans-thoracic echocardiography (TTE) with widely validated and reproducible measures available at the patient's bedside and without the need for invasive procedures involving ionising radiation have established echocardiography as the primary imaging modality. The comprehensive assessment of LVDF is therefore a fundamental element of the standard TTE (Robinson et al. in Echo Res Pract7:G59-G93, 2020. 10.1530/ERP-20-0026). However, the echocardiographic assessment of diastolic function is complex. In the broadest and most basic terms, ventricular diastole comprises an early filling phase when blood is drawn, by suction, into the ventricle as it rapidly recoils and lengthens following the preceding systolic contraction and shortening. This is followed in late diastole by distension of the compliant LV when atrial contraction actively contributes to ventricular filling. When LVDF is normal, ventricular filling is achieved at low pressure both at rest and during exertion. However, this basic description merely summarises the complex physiology that enables the diastolic process and defines it according to the mechanical method by which the ventricles fill, overlooking the myocardial function, properties of chamber compliance and pressure differentials that determine the capacity for LV filling. Unlike ventricular systolic function where single parameters are utilised to define myocardial performance (LV ejection fraction (LVEF) and Global Longitudinal Strain (GLS)), the assessment of diastolic function relies on the interpretation of multiple myocardial and blood-flow velocity parameters, along with left atrial (LA) size and function, in order to diagnose the presence and degree of impairment. The echocardiographic assessment of diastolic function is therefore multifaceted and complex, requiring an algorithmic approach that incorporates parameters of myocardial relaxation/recoil, chamber compliance and function under variable loading conditions and the intra-cavity pressures under which these processes occur. This guideline outlines a structured approach to the assessment of diastolic function and includes recommendations for the assessment of LV relaxation and filling pressures. Non-routine echocardiographic measures are described alongside guidance for application in specific circumstances. Provocative methods for revealing increased filling pressure on exertion are described and novel and emerging modalities considered. For rapid access to the core recommendations of the diastolic guideline, a quick-reference guide (additional file 1) accompanies the main guideline document. This describes in very brief detail the diastolic investigation in each patient group and includes all algorithms and core reference tables.

Role of echocardiography in the contemporary management of chronic heart failure

Echocardiography is an excellent noninvasive tool for the assessment of ventricular size and both systolic and diastolic function, and it is routinely used in patients with heart failure. This review will discuss the role of echocardiography in heart failure diagnosis, prognostic assessment and in the management of heart failure patients.

Influence of regression of left ventricular hypertrophy on left atrial size and function in patients with moderate hypertension

OBJECTIVES

The aim of the study was to evaluate the effect of regression of left ventricular (LV) hypertrophy on left atrial (LA) size and function in patients treated with telmisartan, an angiotensin II receptor blocker.

METHODS

Patients population included 80 patients with mild-moderate LV hypertrophy treated with telmisartan. Patients were followed over a period of 12 months from the start of telmisartan treatment. LA size was measured during systole from the parasternal long-axis view from M-mode. Atrial function was assessed by Doppler-echocardiography and the following parameters were measured: transmitral peak A velocity, atrial filling fraction, atrial ejection force (AEF), peak E velocity, deceleration time and isovolumic relaxation time, LA maximal and minimal volume, and LV cardiac mass index (LVMI).

RESULTS

All patients had an increased LVMI and decrease during follow-up. LA dimensions were greater at baseline and reduced after 1 year of treatment. LA volume indexes maximal volume, minimal volume and P volume were reduced compared with baseline value (maximal volume from 35+/-5 to 32+/-5, p<0.05; minimal volumes from 14+/-2 to 10+/-4, p<0.05). AEF, a parameter of atrial systolic function, increased from 12+/-3 to 15+/-2.4 (p<0.01). The reduction of LA volumes correlate with reduction of LVMI (LA maximal volume and LVMI r = 0.45; p<0.01; LA minimal volume and LVMI r = 0.34; p<0.05). A positive correlation was also found between LV mass index and P volume (r = 0.41; p<0.01), LV mass index and LA active emptying volume (r = 0.39; p<0.01), and LV mass index and LA total emptying volume (r = 0.38; p<0.05).

CONCLUSIONS

The present study suggests that regression of LV hypertrophy due to telmisartan is associated with reduction of LA volumes that expresses variation of LV end-diastolic pressure. The reduction of LV end-diastolic pressure is associated with an increase in diastolic filling and with a significant reduction of active and passive emptying contribution of left atrium to LV stroke volume.

Hemodynamic Consequences of Thoracic Artificial Lung Attachment Configuration: A Computational Model

A thoracic artificial lung (TAL) is being developed to assist treatment of acute and chronic pulmonary dysfunction. The TAL is attached directly to the pulmonary circulation. Depending on pathophysiology, the TAL may be attached in series with the natural lungs (NLs), in parallel with the NLs, or in an intermediate, hybrid configuration. We developed a computational model to study hemodynamic consequences of TAL attachment configuration under pathologic conditions. The pulmonary and systemic circulations, heart, and TAL are modeled as interconnected compliances and conductances, some valved. Time-varying cardiac compliance drives the system and generates pressures and flow rates. The model includes blood pressure feedback from the sympathetic nervous system, renin-angiotensin system, and renal volume control mechanism. We used previously published results from porcine experiments to verify model accuracy. We modeled normal physiology and four disease states. A hybrid configuration with 100% cardiac output through the TAL and 40% through the NLs would deliver maximal blood flow, 3.6 to 4.6 l/min, to the TAL and be tolerated by the right ventricle. Additionally, the model suggests that reducing the large "minor loss" resistances at the graft anastomoses to the pulmonary artery would improve the hemodynamics of all TAL attachment configurations.

Left atrial inflow propagation rate derived by transesophageal color M-mode echocardiography is a promising index of preload

BACKGROUND

Pulmonary capillary wedge pressure (PCWP) is a useful index of preload and an important determinant of cardiac function.

HYPOTHESIS

We postulated that the rate of blood propagating into the left atrium (LAIF-PR) would be a useful measure of PCWP in critically ill patients.

METHODS

Fifty-two critically ill patients (36 men/16 women) receiving mechanical ventilation were studied by multiplane transesophageal echocardiography (TEE). Left atrial inflow propagation rate was measured in systole and diastole as the slope of the color M-mode signal entering the left atrium from the right upper pulmonic vein.

RESULTS

Systolic and diastolic LAIF-PRs were feasible in 49 and 44 patients, respectively. Mean (+/- 1 standard deviation) LAIF-PR in systole was 40 +/- 26 cm/s (range 11-132) and in diastole 34 +/- 22 cm/s (range 5-102). Negative correlations with PCWP (mean 19 +/- 9 mmHg; range 3-40) were good for LAIF-PR in systole (r = -0.71, standard error of estimate [SEE] = 6 mmHg; p < 0.0001) and diastole (r = -0.71, SEE = 6 mmHg; p < 0.0001). Mean ejection fraction was 52 +/- 22% (range 15-88) and cardiac output was 6.97 +/- 3.52 l/min (range 2.26-17.93). Multivariate regression showed PCWP as the only independent predictor of systolic (p < 0.0001) and diastolic (p < 0.0001) LAIF-PR among age, heart rate, cardiac output, ejection fraction, or left atrial diameter.

CONCLUSIONS

Left atrial inflow propagation rate derived by color M-mode TEE aligned with the right upper pulmonic vein is a promising new index of preload. Future studies addressing the determinants of LAIF-PR, such as left atrial compliance, are needed.

A Novel Method to Estimate Pulmonary Artery Wedge Pressure Using the Downslope of the Doppler Mitral Regurgitant Velocity Profile

Continuous-wave (CW) Doppler recording of mitral regurgitation (MR) is a reflection of the left ventriculoatrial pressure gradient. Accordingly, this jet may yield information about pulmonary artery wedge pressure (PAWP). In this study, we derived and then evaluated a novel method for prediction of PAWP. Patients (n=80) with moderate to severe MR and left ventricular dysfunction were included in the study. Transthoracic echocardiography was performed in patients during pulmonary artery pressure monitoring. A satisfactory CW Doppler recording of MR was obtained in 63/80 (78%). On the late descending portion of the CW recording, the time from a velocity of 4 m/sec to the end of the jet was defined as t1, and from 3 m/sec to the end of the jet as t2. Mathematical derivation of t1/t2 as a predictor of PAWP, was performed based on Weiss' derivation. If t1/t2 was <1.30, the PAWP was normal. If t1/t2 > 1.44, the PAWP was > 16 mmHg. With this new mathematical derivation, it appears that the downslope of the CW Doppler MR waveform may be able to distinguish a normal from elevated PAWP.

MRI and echocardiographic assessment of the diastolic dysfunction of normal aging: altered LV pressure decline or load?

Changes in diastolic indexes during normal aging, including reduced early filling velocity ( E), lengthened E deceleration time (DT), augmented late filling ( A), and prolonged isovolumic relaxation time (IVRT), have been attributed to slower left ventricular (LV) pressure (LVP) decay. Indeed, this constellation of findings is often referred to as the “abnormal relaxation” pattern. However, LV filling is determined by the atrioventricular pressure gradient, which depends on both LVP decline and left atrial (LA) pressure (LAP). To assess the relative influence of LVP decline and LAP, we studied 122 normal subjects aged 21–92 yr by Doppler echocardiography and MRI. LVP decline was assessed by color M-mode ( Vp) and the LV untwisting rate. Early diastolic LAP was evaluated using pulmonary vein flow systolic fraction, pulmonary vein flow diastolic DT, color M-mode ( E/ Vp), and tissue Doppler ( E/ Em). Linear regression showed the expected reduction of E, increase in A, and prolongation of IVRT and DT with advancing age. There was no relation of age to parameters reflecting the rate of LVP decline. However, older age was associated with reduced E/ Vp ( P = 0.008) and increased pulmonary vein systolic fraction ( P < 0.001), pulmonary vein DT ( P = 0.0026), and E/ Em ( P < 0.0001), all suggesting reduced early LAP. Therefore, reduced early filling in older adults may be more closely related to a reduced early diastolic LAP than to slower LVP decline. This effect also explains the prolonged IVRT. We postulate that changes in LA active or passive properties may contribute to development of the abnormal relaxation pattern during the aging process.

Pulmonary venous flow by doppler echocardiography: revisited 12 years later

In 2003, pulmonary venous flow (PVF) evaluation by Doppler echocardiography is being used daily in clinical practice. Twelve years ago, we reviewed the potential uses of PVF in various conditions. Some of its important uses in cardiology have materialized, while others have not and have been supplanted by newer approaches. Current applications of measuring PVF have included: differentiating constrictive pericarditis from restriction, estimation of left ventricular (LV) filling pressures, evaluation of LV diastolic dysfunction and left atrial (LA) function, and grading the severity of mitral regurgitation (MR). However, there have been a number of controversies raised in the use of PVF profiles. Using transthoracic echocardiography, there may be technical issues in measuring the atrial reversal flow velocity. The use of PVF in the evaluation of the severity of MR is not always specific and can be affected by atrial fibrillation (AF) and elevated mean LA pressure. Mitral valvuloplasty and radiofrequency ablation for AF, which are the newer applications of PVF in monitoring invasive procedures, are mentioned. This article reviews the important clinical role of Doppler evaluation of PVF, discusses its limitations and pitfalls, and highlights its newer applications.

Pulmonary venous systolic flow: influence of gravity on pulmonary venous flow velocities assessed in patients with atrial fibrillation

The origin of the pulmonary venous (PV) systolic flow wave is still unclear and could be the atrial relaxation and systolic descent of the atrioventricular plane, which decrease atrial pressure (suction) or raised PV pressure. In atrial fibrillation (AF), loss of atrial contraction and relaxation significantly modifies the systolic PV flow wave. The effect of recumbent positional changes on PV, however, has not yet been characterized in AF. The purpose of this study was to evaluate the effect of positional changes on systolic PV flow in patients with AF studied by transesophageal echocardiography. The study group consisted of 45 patients with AF (34 patients with AF, alone, and 11 patients with mitral stenosis [MS]). To assess the influence of left atrial pressure, we included patients with MS and AF. Pulsed wave Doppler transesophageal echocardiography of the left and right upper PV were performed in the left lateral recumbent position in all patients and repeated records were obtained with the subject in the supine position in 25 (AF alone: n = 20, MS: n = 5) of 45 patients. In the left lateral recumbent position, the systolic PV flow velocity and systolic fraction of the left PV, which were recorded on the recumbent subject's lower side, were significantly increased compared with those of the right PV in both AF alone and MS with AF (33.9 +/- 10.8 vs 13.8 +/- 6.4 cm/s, 0.45 +/- 0.09 vs 0.20 +/- 0.10 in AF alone; 30.2 +/- 11.7 vs 14.6 +/- 6.0 cm/s, 0.43 +/- 0.12 vs 0.20 +/- 0.07 in MS, respectively, P < .01). By changing the position from the left lateral to the supine position, systolic PV flow velocity and systolic fraction of the left and right PV became the same (29.3 +/- 8.4 vs 27.9 +/- 8.4 cm/s, 0.39 +/- 0.09 vs 0.36 +/- 0.06 in AF alone, 23.5 +/- 8.8 vs 27.5 +/- 5.0 cm/s, 0.35 +/- 0.08 vs 0.35 +/- 0.09 in MS, respectively). These findings show that the PV volume (hydrostatic pressure) significantly modifies systolic PV flow wave in patients without atrial contraction and relaxation. We should take into consideration the body position on which PV flow is studied.

Left atrial inflow propagation rate: a new transesophageal echocardiographic index of preload

We postulated that the rate of blood propagating into the left atrium from the left upper pulmonic vein would be a useful measure of pulmonary capillary wedge pressure (PCWP). In 23 adult patients who were critically ill (ie, study group) and receiving mechanical ventilation, color M-mode multiplane transesophageal echocardiography was used to measure left atrial inflow propagation rate (LAIF-PR) as a potential index of PCWP measured by right heart catheterization. LAIF-PR was measured in systole and diastole as the slope of the color M-mode signal entering the left atrium from the left upper pulmonic vein. Correlation with PCWP was good for systolic (r = -0.847, P < .0001) and diastolic (r = -0.78, P < .0001) LAIF-PR. The reliability of univariate linear regression equations derived from the study group was tested in 29 subsequent patients (ie, testing group). Measured PCWP was accurately estimated within 5 mm Hg in 85% (22 of 26 patients) and 68% (17 of 25 patients) of the testing group by systolic and diastolic LAIF-PR, respectively. Color M-mode transesophageal echocardiography-derived LAIF-PR, particularly in systole, is a promising new index to estimate PCWP in patients who are critically ill.

Prediction of mean pulmonary wedge pressure using doppler pulmonary venous flow variables in hypertrophic cardiomyopathy

We examined whether pulmonary venous flow variables, assessed by transthoracic Doppler echocardiography, could predict mean pulmonary wedge pressure in hypertrophic cardiomyopathy. Forty-four patients with no left ventricular systolic dysfunction (left ventricular fractional shortening > or =25%) were studied. Forty patients with systolic dysfunction (dilated cardiomyopathy group) served as control. Mitral and pulmonary venous flow velocity curves were recorded with the pulsed-Doppler method and were related to mean pulmonary wedge pressure obtained by right heart catheterization. In hypertrophic cardiomyopathy group, the systolic (r=-0.15, P=0.335) and diastolic (r=0.35, P=0.022) forward flow velocity were poorly related to mean pulmonary wedge pressure, whereas the velocity of atrial reversal (r=0.68, P<0.001) correlated well with mean pulmonary wedge pressure. In dilated cardiomyopathy group, the systolic (r=-0.51, P=0.001) and diastolic (r=0.60, P<0.001) forward flow velocity were strongly related to mean pulmonary wedge pressure. With the cut-off value set at the velocity of atrial reversal >30 cm/s in hypertrophic cardiomyopathy group, the sensitivity for predicting mean pulmonary wedge pressure >15 mmHg was 79% and the specificity was 73%. In conclusion, the atrial component of the pulmonary venous flow can be used to predict mean pulmonary wedge pressure in hypertrophic cardiomyopathy.

Determinants of forward pulmonary vein flow: an open pericardium pig model

OBJECTIVE

To elucidate determinants of pulmonary venous (PV) flow.

BACKGROUND

Right ventricular (RV) systolic pressure (vis a tergo), left atrial (LA) relaxation and left ventricular (LV) systole and relaxation (vis a fronte) have been suggested as determinants of the pulmonary venous (PV) anterograde Doppler flow velocities, but their relative contributions to those flow velocities have not been quantified.

METHODS

We analyzed, by multiple regression analysis, the determinants of PV anterograde velocities in an open-pericardium, paced (70 and 90 beats/min) pig model in which LA afterload was modified by creating LV regional ischemia (left anterior descending coronary artery constriction). We measured high fidelity LA, LV and RV pressures and Doppler flow velocities (epicardial echocardiography). We calculated LV tau, LA relaxation (a through x pressure difference divided by time, normalized by a pressure), LA peak v through x and RV systolic through LA peak v (RVSP-v) pressure differences, LV ejection fraction, long-axis shortening, stroke volume (LV outflow integral x outflow area) and LA four-chamber dimensions, Doppler transmitral and PV flow velocities and velocity-time integrals.

RESULTS

Left ventricular regional ischemia increased mildly LA y trough pressure (8 +/- 1 vs. 6 +/- 1 mm Hg, p = 0.001). Left ventricular stroke volume (coefficient: 0.5 cm/ml, SE: 0.2, p = 0.005) and LA peak v pressure (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.008) determined the PV total systolic integral. Left atrial relaxation determined both PV early systolic peak velocity and integral (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.04). Left atrial maximum area (coefficient: 2 cm(-1) SE: 0.7, p = 0.01) and RVSP-v (coefficient: 0.1 cm/mm Hg, SE: 0.05, p = 0.03) determined the late systolic integral. The PV total systolic integral determined both PV early diastolic peak velocity and integral (coefficient: 1.2, SE: 0.2, p = 0.001).

CONCLUSIONS

In an experimental model of LV acute ischemia of limited duration, the main independent predictors of PV systolic anterograde flow velocities are LA relaxation and compliance (LA peak v pressure) and LV systole--all vis a fronte factors. In the setting of mildly increased LA pressures, PV systolic flow (LA reservoir filling) is an independent predictor of PV early diastolic flow (LA early conduit).

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

BACKGROUND

In patients with chronic heart failure, pulmonary hypertension is an important predictive marker of adverse outcome. Its invasive and non-invasive determinants have not been evaluated.

OBJECTIVE

This study was performed to evaluate hemodynamic determinants of pulmonary hypertension in chronic heart failure and to compare the predictive value of Doppler indices with that of invasively measured hemodynamic indices.

METHODS

Right heart catheterization and transthoracic echo-Doppler were simultaneously performed in 259 consecutive patients with chronic heart failure (ejection fraction 24% +/- 7%) who were in sinus rhythm and receiving optimized medical therapy. Systolic pulmonary artery pressure (sPAP), cardiac index, transpulmonary gradient pressure, and pulmonary wedge pressure (PWP) were measured invasively. Left atrial and ventricular systolic and diastolic volumes, the ratio of maximal early to late diastolic filling velocities (E/A ratio), deceleration time (DT) and atrial filling fraction (AFF) of transmitral flow, systolic fraction of forward pulmonary venous flow (SFpvf), and mitral regurgitation were quantified by echo-Doppler.

RESULTS

Patients with pulmonary hypertension had greater left atrial systolic and diastolic dysfunction, more left ventricular diastolic abnormalities, and greater hemodynamic impairment. The correlations between systolic left ventricular indices, mitral regurgitation, and sPAP were generally poor. Among invasive and non-invasive measurements, PWP (r = 0.89, p < 0.0001) and SFpvf (r = -0.68, p < 0.0001) showed the strongest correlation with sPAP. When we compared all patients with those without mitral regurgitation, the correlations between E/A ratio (r = 0.56 vs r = 0. 74, p < 0.002), SFpvf (r = -0.68 vs r = -0.84, p < 0.03), and systolic pulmonary artery pressure were significantly stronger. Multivariate analysis revealed that PWP was the strongest invasive independent predictor of systolic pulmonary artery pressure in patients with (R(2) = 0.87, p < 0.0001) and without (R(2) = 0.90, p < 0.0001) mitral regurgitation. A PWP > or= 18 mm Hg (odds ratio [95% CL], 142 (41-570) was strongly associated with systolic pulmonary hypertension. Among non-invasive variables DT, SFpvf, and AFF were identified as independent predictors of sPAP in patients with (R(2) = 0.56, p < 0.0001) and without (R(2) = 0.78, p < 0.0001) mitral regurgitation. A DT < 130 (odds ratio [95% CL], 3.5 (1.3-8.5), SFfvp < 40% (odds ratio [95% CL], 333 (41-1,007), and AFF < 30% (odds ratio [95% CL], 2 (1.3-7) most strongly predicted systolic pulmonary hypertension.

CONCLUSIONS

The results of this study indicate that in patients with chronic heart failure, venous pulmonary congestion is an important determinant of systolic pulmonary artery hypertension. Hemodynamic and Doppler determinants showed similar predictive power in identifying systolic pulmonary artery hypertension.

The value of assessing pulmonary venous flow velocity for predicting severity of mitral regurgitation: A quantitative assessment integrating left ventricular function

Although alteration in pulmonary venous flow has been reported to relate to mitral regurgitant severity, it is also known to vary with left ventricular (LV) systolic and diastolic dysfunction. There are few data relating pulmonary venous flow to quantitative indexes of mitral regurgitation (MR). The object of this study was to assess quantitatively the accuracy of pulmonary venous flow for predicting MR severity by using transesophageal echocardiographic measurement in patients with variable LV dysfunction. This study consisted of 73 patients undergoing heart surgery with mild to severe MR. Regurgitant orifice area (ROA), regurgitant stroke volume (RSV), and regurgitant fraction (RF) were obtained by quantitative transesophageal echocardiography and proximal isovelocity surface area. Both left and right upper pulmonary venous flow velocities were recorded and their patterns classified by the ratio of systolic to diastolic velocity: normal (>/=1), blunted (<1), and systolic reversal (<0). Twenty-three percent of patients had discordant patterns between the left and right veins. When the most abnormal patterns either in the left or right vein were used for analysis, the ratio of peak systolic to diastolic flow velocity was negatively correlated with ROA (r = -0.74, P <.001), RSV (r = -0.70, P <.001), and RF (r = -0.66, P <.001) calculated by the Doppler thermodilution method; values were r = -0.70, r = -0.67, and r = -0.57, respectively (all P <.001), for indexes calculated by the proximal isovelocity surface area method. The sensitivity, specificity, and predictive values of the reversed pulmonary venous flow pattern for detecting a large ROA (>0.3 cm(2)) were 69%, 98%, and 97%, respectively. The sensitivity, specificity, and predictive values of the normal pulmonary venous flow pattern for detecting a small ROA (<0.3 cm(2)) were 60%, 96%, and 94%, respectively. However, the blunted pattern had low sensitivity (22%), specificity (61%), and predictive values (30%) for detecting ROA of greater than 0.3 cm(2) with significant overlap with the reversed and normal patterns. Among patients with the blunted pattern, the correlation between the systolic to diastolic velocity ratio was worse in those with LV dysfunction (ejection fraction <50%, r = 0.23, P >.05) than in those with normal LV function (r = -0.57, P <.05). Stepwise linear regression analysis showed that the peak systolic to diastolic velocity ratio was independently correlated with RF (P <.001) and effective stroke volume (P <.01), with a multiple correlation coefficient of 0.71 (P <.001). In conclusion, reversed pulmonary venous flow in systole is a highly specific and reliable marker of moderately severe or severe MR with an ROA greater than 0.3 cm(2), whereas the normal pattern accurately predicts mild to moderate MR. Blunted pulmonary venous flow can be seen in all grades of MR with low predictive value for severity of MR, especially in the presence of LV dysfunction. The blunted pulmonary venous flow pattern must therefore be interpreted cautiously in clinical practice as a marker for severity of MR.

The pulmonary venous systolic flow pulse--its origin and relationship to left atrial pressure

OBJECTIVES

The purpose of this study was to determine the origin of the pulmonary venous systolic flow pulse using wave-intensity analysis to separate forward- and backward-going waves.

BACKGROUND

The mechanism of the pulmonary venous systolic flow pulse is unclear and could be a "suction effect" due to a fall in atrial pressure (backward-going wave) or a "pushing effect" due to forward-propagation of right ventricular (RV) pressure (forward-going wave).

METHODS

In eight patients during coronary surgery, pulmonary venous flow (flow probe), velocity (microsensor) and pressure (micromanometer) were recorded. We calculated wave intensity (dP x dU) as change in pulmonary venous pressure (dP) times change in velocity (dU) at 5 ms intervals. When dP x dU > 0 there is a net forward-going wave and when dP x dU < 0 there is a net backward-going wave.

RESULTS

Systolic pulmonary venous flow was biphasic. When flow accelerated in early systole (S1), pulmonary venous pressure was falling, and, therefore, dP x dU was negative, -0.6 +/- 0.2 (x +/- SE) W/m2, indicating a net backward-going wave. When flow accelerated in late systole (S2), pressure was rising, and, therefore, dP x dU was positive, 0.3 +/- 0.1 W/m2, indicating a net forward-going wave.

CONCLUSIONS

Pulmonary venous flow acceleration in S1 was attributed to a net backward-going wave secondary to a fall in atrial pressure. However, flow acceleration in S2 was attributed to a net forward-going wave, consistent with propagation of the RV systolic pressure pulse across the lungs. Pulmonary vein systolic flow pattern, therefore, appears to be determined by right- as well as left-sided cardiac events.

Influence of gravity on pulmonary venous flow velocity patterns: analysis of left and right pulmonary venous flow velocities in left and right decubitus positions

BACKGROUND

The pulmonary venous flow signal measured by transesophageal echocardiography is generally recorded from the left upper pulmonary vein in the left lateral decubitus position, whereas that by transthoracic echocardiography is from the right upper pulmonary vein in the left semi-lateral decubitus position. The purpose of this study was to evaluate the influence of the postural change on the peak flow velocities of the left and right pulmonary veins and whether the parameters of the left and right pulmonary venous flow can be used interchangeably.

METHODS AND RESULTS

The study group consisted of 37 patients with normal left ventricular filling pressure and in whom the systolic forward flow signals from both pulmonary veins recorded in the left and right lateral decubitus positions were clear enough to differentiate as biphasic. The peak early systolic (peak S1) and diastolic velocities were significantly increased when the pulmonary vein was on the recumbent subject's upper side, whereas the peak late systolic velocity (peak S2) was significantly increased when the pulmonary vein was on the recumbent subject's lower side. The peak S1 was higher than the peak S2 when the pulmonary vein was on the recumbent subject's upper side, whereas the reverse relation was seen when the pulmonary vein was on the recumbent subject's lower side.

CONCLUSIONS

We should take into consideration the body position and the side on which the pulmonary vein is situated in evaluating the peak flow velocities of the pulmonary veins.

Transthoracic Doppler echocardiography of normally originating coronary arteries in children

Transthoracic Doppler color flow and spectral velocity patterns of normal coronary arteries in children have not been well studied. We designed this study to evaluate coronary artery flow velocity characteristics in normal and hypertrophied hearts. Sixty-eight children with optimal two-dimensional echocardiographic images of the left coronary artery (LCA) and right coronary artery (RCA) were prospectively studied. The heart was normal in 45 children, and 23 had left and/or right ventricular hypertrophy assessed by echocardiography (mean age 5.8 versus 5.2 years, p = NS). Color flow signals were detected in the LCA in 63(92%) of the 68 children studied, and pulsed Doppler spectral waveforms were recorded in 47 (69%). The latter were recorded in 26 (58%) of 45 normal children and in 21 (91%) of 23 children with left ventricular hypertrophy. Diastolic RCA flow signals were detected mostly in those with right ventricular hypertrophy (10 of 10). Higher levels of LCA maximum diastolic velocity (42 +/- 23 versus 24 +/- 6 cm/sec, p = 0.0004), increased diastolic flow (16 +/- 15 versus 6 +/- 4 ml/min, p = 0.01), and delayed time to peak diastolic velocity expressed as a percentage of diastolic spectral duration (38% +/- 14% versus 20% +/- 8%, p = 0.0001) were observed in children with left ventricular hypertrophy than in those in normal children. A strong correlation was present between Doppler-derived LCA flow and left ventricular mass/m2 (r = 0.7, p = 0.001). In normal hearts, LCA spectral velocity pattern did not change with increasing age, but the time velocity integral became progressively larger, resulting in a strong correlation with weight (p < 0.001, r = 0.78). This study demonstrates (1) LCA flow signals can be detected and quantitated in the majority of children with and those without left ventricular hypertrophy. (2) Left ventricular hypertrophy is associated with increased LCA flow, higher diastolic velocity, and delayed peak diastolic velocity. (3) RCA flow signals are mostly detected when there is right ventricular hypertrophy. Studies on larger groups of patients are needed to further confirm our observations and to enhance understanding of coronary artery flow reserve.

Left atrial function in congestive heart failure: assessment by transmitral and pulmonary vein Doppler

The relation of transmitral flow patterns and pulmonary venous velocities was analyzed from 50 heart failure patients (28 men, 22 women; mean [+/- SD] age 61 +/- 9 years) with a left ventricular ejection fraction < 40%. Doppler echocardiography was performed in all patients. Transmitral flow measurements included early (E) and atrial (A) velocities and deceleration time of E wave (DT). Patients were assigned to two groups according to E/A ratio, DT, or both: 20 patients in the restrictive group, and 30 patients in the nonrestrictive group. Pulmonary venous flow was obtained by the transthoracic approach. Systolic (S), diastolic (D) and atrial reversal (Ar) velocities were measured. Of the study population, 13 patients had simultaneously determined pulmonary capillary wedge pressure (PCWP). The results showed a lower S (28 +/- 11 vs. 51 +/- 10 cm/sec, p < 0.01), a higher D (66 +/- 13 vs. 44 +/- 10 cm/sec, p < 0.01) and a smaller Ar (12 +/- 10 vs. 24 +/- 9 cm/sec, p < 0.01) in the restrictive group compared with those in nonrestrictive group. In the subgroup of patients undergoing invasive hemodynamic studies, there was no relationship between PCWP and atrial reversal velocity. However, a significant correlation was observed for pulmonary systolic (r = -0.70, p < 0.01) and diastolic (r = 0.76, p < 0.01) velocities to PCWP. These findings suggest a reduction in left atrial compliance and atrial systolic function and both play important roles in heart failure patients with the restrictive transmitral flow pattern.

Estimation of the pulmonary capillary wedge pressure from transesophageal pulsed Doppler echocardiography of pulmonary venous flow: influence of the respiratory cycle during mechanical ventilation

OBJECTIVE

Pulsed Doppler measurement of pulmonary venous flow (PVF) in the left superior pulmonary vein has been suggested as a noninvasive method to evaluate pulmonary capillary wedge pressure (PCWP). In previous studies, PVF was measured at end-expiration, and it is unknown to what extent PVF is affected by the respiratory cycle. It is hypothesized that phasic variations of PVF during mechanical ventilation may be used to estimate PCWP.

DESIGN

Prospective clinical study.

SETTING

Tertiary care university hospital.

PARTICIPANTS

Thirty patients undergoing elective cardiac surgery.

INTERVENTIONS

At multiple intervals during the surgery, the PVF was measured with transesophageal pulsed Doppler echocardiography, and measurements of PCWP and airway pressure were simultaneously obtained.

MEASUREMENTS AND RESULTS

Components of PVF evaluated were the systolic (X), diastolic (Y), and atrial (Z) waves with their velocity-time integrals (VTI). The systolic fraction (SF = VTI X/[VTI X + VTI Y]) and respiratory variations of each component of PVF were determined and compared with PCWP. There was a greater respiratory variation of the X wave (X expiratory-X inspiratory/X expiratory) in patients with PCWP < 18 mmHg than in patients with PCWP > or = 18 mmHg (0.19 +/- 0.19 v 0.14 +/- 0.13, respectively, p < 0.01). PVF components measured at end-expiration that related best with PCWP were the X/Y peak velocities (r = -0.53), VTI X/VTI Y ratio (r = -0.42), and the SF (r = -0.49). When measured during end-inspiration, the relation of the X/Y ratio, VTI X/VTI Y, and SF with the PCWP were r = -0.54, r = -0.41, and r = -0.50, respectively.

CONCLUSIONS

It has been documented that PVF velocity is influenced by the respiratory cycle during mechanical ventilation in patients undergoing cardiac surgery, and the magnitude of this variation is influenced by PCWP. However, it is not actually possible to predict PCWP accurately using these findings. Further studies are needed in which preload is varied acutely to confirm the usefulness of the results.

Hemodynamic determinants of Doppler pulmonary venous flow velocity components: new insights from studies in lightly sedated normal dogs

OBJECTIVES

We sought to define the hemodynamic determinants of pulmonary venous (PV) flow velocities to assess how these are affected by respiration, heart rate and loading conditions.

BACKGROUND

Pulmonary venous flow velocity (PVFV) recorded with pulsed wave Doppler technique is currently used in the noninvasive evaluation of left ventricular (LV) diastolic function and filling pressures. Although previous studies in both animals and humans have shown that PV flow is pulsatile, the hemodynamic determinants of the individual components of this flow remain controversial. Understanding the physiologic mechanisms should help to better define the clinical utility of these Doppler techniques.

METHODS

PV flow velocities obtained with transesophageal pulsed wave Doppler imaging were recorded together with PV, left atrial (LA) and LV pressures in 10 sedated, spontaneously breathing normal dogs. PVFV and hemodynamic data were analyzed during apnea, inspiration and expiration, at atrial paced heart rates of 60, 80, 100 and 120 beats/min and mean LA pressures of 6, 12, 18 and 24 mm Hg.

RESULTS

The data showed that 1) PV pressure varied depending on recording site, resembling pulmonary artery pressure closer to the pulmonary capillary bed and LA pressure closer to the venoatrial junction; 2) PVFV qualitatively followed changes in the PV-LA pressure gradient; 3) four PVFV components exist under normal conditions-three of which follow phasic changes in LA pressure and one of which (the late systolic component) is more influenced by RV stroke volume and the compliance of the pulmonary veins and left atrium; 4) normal respiration and changes in heart rate significantly alter PVFV variables--in particular, reverse flow velocity at atrial contraction; and 5) increasing LA pressure results in larger PV A wave and PV early systolic flow velocities, as well as an earlier peak in PV late systolic flow velocity and a more prominent velocity minimum before PV diastolic flow.

CONCLUSIONS

Using transesophageal pulsed wave Doppler technique, four PVFV components are identifiable and determined by PV-LA hemodynamic pressure gradients. These gradients appear to be influenced by a combination of physiologic events that include RV stroke volume, the compliance of the pulmonary vasculature and left atrium and phasic changes in LA pressure. PV flow velocity components are significantly influenced by heart rate, respiration and LA pressure. These findings have implications for the interpretation of LV diastolic function and filling pressures by current Doppler echocardiographic techniques but require further clinical investigation.

Estimating mean pulmonary wedge pressure in patients with chronic atrial fibrillation from transthoracic Doppler indexes of mitral and pulmonary venous flow velocity

OBJECTIVES

We sought to obtain a noninvasive estimation of mean pulmonary wedge pressure (MPWP) in patients with chronic atrial fibrillation (AF).

BACKGROUND

It has previously been demonstrated that MPWP can be reliably estimated from Doppler indexes of mitral and pulmonary venous flow (PVF) in patients with sinus rhythm. Doppler estimation of MPWP has not been validated in patients with AF.

METHODS

MPWP was correlated with variables of mitral and pulmonary venous flow velocity as assessed by Doppler transthoracic echocardiography in 35 consecutive patients. The derived algorithm was prospectively tested in 23 additional patients.

RESULTS

In all patients the mitral flow pattern showed only a diastolic forward component. A significant but relatively weak correlation (r = -0.50) was observed between MPWP and mitral deceleration time. In 12 (34%) of 35 patients, the pulmonary vein flow tracing demonstrated only a diastolic forward component; a diastolic and late systolic forward flow was noted in the remaining 23 patients (66%). A strong negative correlation was observed between MPWP and the normalized duration of the diastolic flow (r = -0.80) and its initial deceleration slope time (r = -0.91). Deceleration time > 220 ms predicted MPWP < or = 12 mm Hg with 100% sensitivity and 100% specificity. When estimating MPWP by using the equation MPWP = -94.261 PVF deceleration time -9.831 Interval QRS to onset of diastolic PVF -16.337 Duration of PVF + 44.261, the measured and predicted MPWP closely agreed with a mean difference of -0.85 mm Hg. The 95% confidence limits were 4.8 and -6.1 mm Hg.

CONCLUSIONS

In patients with chronic AF, MPWP can be estimated from transthoracic Doppler study of PVF velocity signals.

The association between Doppler transmitral flow variables measured by transesophageal echocardiography and pulmonary capillary wedge pressure

The association between Doppler transmitral flow variables, measured by transesophageal echocardiography (TEE), and pulmonary capillary wedge pressure (PCWP) was studied in 88 patients undergoing coronary artery surgery. The Doppler flow variables and PCWP were measured after sternotomy by blinded investigators. In the first part of the study, patients were divided into two groups according to left ventricular (LV) ejection fraction (EF): Group A, EF > 35% (n = 38) and Group B, EF < or = 35% (n = 34). In Group B, significant correlations were found between deceleration time of early filling (DCT-E) and PCWP (r2 = 0.899) and deceleration slope of early filling and PCWP (r2 = 0.692), (P < 0.001 for both). When the relationship between DCT-E and PCWP was tested prospectively in a third group of patients [Group C; EF < or = 35% (n = 16)], a close agreement between the calculated and measured PCWP (bias = -0.55 +/- 3.87 mm Hg) was noted. The sensitivity, specificity, and positive predictive value of DCT-E > or = 150 ms for PCWP < 10 mm Hg were 93.3%, 100%, and 100%, respectively. In summary, patients with decreased left ventricular systolic function undergoing coronary artery surgery demonstrated high, statistically significant, correlations between PCWP and the deceleration time or deceleration slope of early diastolic filling as measured by transesophageal Doppler echocardiography.