Pulmonary venous flow as assessed by Doppler echocardiography: potential clinical applications

Pulmonary pulse transit time: a novel echocardiographic indicator of hemodynamic and vascular alterations in pulmonary hypertension and pulmonary fibrosis

INTRODUCTION

Pulse transit time (PTT) is generally assumed to be a surrogate marker for blood pressure changes and arterial stiffness. The aim was to evaluate whether pulmonary PTT (pPTT) may be noninvasively measured by Doppler echocardiography and whether it might be valuable for detecting pulmonary hemodynamic and vascular alterations.

METHODS

We defined pPTT as the interval between R-wave in the ECG and the corresponding peak late systolic pulmonary vein flow velocity measured by pw-Doppler in the pulmonary vein. Twelve consecutive patients with pulmonary hypertension (PH) and 12 subjects without any cardiovascular or respiratory disease were included in the study. All patients underwent a standard echocardiography including pPTT measurement.

RESULTS

In the PH group, 5 patients had idiopathic pulmonary arterial hypertension (WHO 1), 1 patient PH associated with connective tissue disease (CTD, WHO 1) without pulmonary fibrosis (PF), and 6 patients PH associated with PF either due to CTD (WHO 1) or other etiology (WHO 3). Mean pPTT was significantly shorter in the PH group (138.0 ± 16.78 msec; P < 0.0001) than in the control group (383.5 ± 23.84 msec). Within the PH group, the subgroup of patients with PF showed significantly shorter mean pPTT (93.50 ± 15.47 msec; P = 0.004) than the subgroup of patients with PH without PF (182.6 ± 14.35 msec).

CONCLUSIONS

The results of this study suggest that pPTT might be an interesting surrogate marker of pulmonary hemodynamic and vascular alterations in PH and PF. Further studies are warranted to evaluate the possible influence of other variables on pPTT.

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.

Prognostic value of pulmonary venous flow Doppler signal in left ventricular dysfunction: contribution of the difference in duration of pulmonary venous and mitral flow at atrial contraction

OBJECTIVES

We assessed the contribution of difference in duration of pulmonary venous and mitral flow at atrial contraction (ARd-Ad) for prognostic stratification of patients with left ventricular (LV) systolic dysfunction.

BACKGROUND

Although pulmonary venous flow (PVF) variables may supplement mitral flow patterns in evaluating left ventricular (LV) diastolic function, their value to the prognostic stratification of patients has not been investigated.

METHODS

Pulsed wave Doppler mitral and PVF velocity curves were recorded in 145 patients (mean age: 70 years) with LV systolic dysfunction secondary to ischemic or nonischemic cardiomyopathy who were followed for 15 +/- 8 months. In 38% of patients, PVF signal was enhanced by the intravenous (IV) administration of a galactose-based echo-contrast agent. Based on E-wave deceleration time < or = or >130 ms and ARd-Ad, patients were grouped into restrictive (group 1, n = 40), nonrestrictive with ARd-Ad > or =30 ms (group 2, n = 55) and nonrestrictive with ARd-Ad <30 ms (group 3, n = 50).

RESULTS

During follow-up, 29 patients died from cardiac causes and 28 were hospitalized for worsening heart failure (HF). On multivariate Cox model, ARd-Ad > or =30 ms provided important prognostic information with regard to cardiac mortality and emerged as the single best predictor of cardiac events (cardiac mortality, hospitalization). The 24-month cardiac event-free survival was best (86.3%) for group 3; it was intermediate (37.9%) for group 2; and it was worst (22.9%) for group 1 (p < 0.0002 group 1 vs. 3; p < 0.0005 group 2 vs. 3; p < 0.0003 group 1 vs. group 2).

CONCLUSIONS

Assessment of ARd-Ad exhibited an independent value in the prognostic evaluation of patients with LV systolic dysfunction. Moreover, it contributed to identify patients at low, intermediate and high risk of cardiac events.

Transesophageal Doppler echocardiographic study of pulmonary venous flow pattern in severe mitral stenosis and the changes following balloon mitral valvuloplasty

The studies of pulmonary venous flow-pattern in mitral stenosis (MS) have given conflicting data about the type of abnormality. This study was undertaken to assess the pulmonary venous flow-pattern in severe MS and to study the changes occurring after balloon mitral valvuloplasty (BMV). There were 51 patients of MS with sinus rhythm with the mean age of 32.5+/-9.35 years, 18 males and 33 females. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were performed before and after BMV. Pulmonary venous flow was recorded by TEE from left upper pulmonary vein (PV). Peak velocities (V) and velocity time integrals (VTI) of systolic wave (S), diastolic wave (D), and atrial reversal wave (A) were measured. The S(v)/D(v) and S(VTI)/D(VTI) were calculated. Mitral valve area (MVA) increased from 0.81+/-0.18 cm(2) to 2.02+/-0.46 cm(2), left atrium (LA) mean decreased from 28.55+/-6.68 mmHg to 13.88+/-4.89 mmHg, and cardiac output increased from 3.1+/-0.86 L/min to 3.7+/-1.02 L/min. The S, D, and A velocities increased from 33.84+/-13.55 cm/s, 37.24+/-11.55 cm/s, and 20.53+/-6.7 cm/s to 59.86+/-18.25 cm/s, 48.43+/- 12.55 cm/s, and 24. 94+/-9.14 cm/s, respectively. The VTIs of S, D, and A waves increased from 4.88+/-2.24 cm, 6+/-2.45 cm, and 2+/-0.88 cm to 10.46+/-4.23 cm, 8.82+/-3.61 cm, and 2.34+/-1.29 cm, respectively. MS leads to reduction in pulmonary flow velocities during all the phases. Successful BMV resulted in improvement of all these velocities, with improvement in systolic fraction being the maximum. These improved flows after BMV appear to be secondary to reduction in LA pressure and improved cardiac output.

Relationship Between Echocardiographic Determinants of Left Atrial Spontaneous Echo Contrast and Thrombus Formation in Patients with Rheumatic Mitral Valve Disease

Spontaneous echo contrast (SEC) may be detected by ultrasonography in environments favoring blood stasis. It is most commonly seen through the use of transesophageal echocardiography in the left atrium of patients with rheumatic mitral valve disease especially in the presence of atrial fibrillation. We studied the predictors of SEC, such as cardiac rhythm, left atrium and left atrial appendage functions, and mitral and pulmonary vein flow parameters, in patients with rheumatic mitral valve disease. The relationship between these parameters and the severity of SEC and appearance of thrombus was evaluated.

Left Ventricular Diastolic Function in a Population Sample of Elderly Men

BACKGROUND AND METHODS: Echocardiography with Doppler has been widely used to assess left ventricular (LV) diastolic function. Interpretation of the diastolic indices that are derived, however, is confounded by the effects of physiological aging on the LV diastolic function. In this study, the usefulness of different Doppler-derived indices of LV diastolic function was assessed in elderly subjects by using data from a health screening survey of 584 men aged 70 years. RESULTS: The index of early versus late transmitral blood flow, the E/A ratio, was found to be reduced in the apparently healthy subgroup (n = 195) of the population (0.96 +/- 0.25) compared with previous data from middle-aged subjects. However, E/A ratios similar to those in the apparently healthy subjects were found in subjects with coronary heart disease (CHD), hypertension, and diabetes mellitus. Only subjects with systolic dysfunction (ejection fraction < 40%) showed a significantly decreased E/A ratio (0.79 +/- 0.21, P < 0.05) compared with the apparently healthy subjects. Isovolumic relaxation time (IVRT) was, however, significantly prolonged in subjects with CHD or hypertension compared with the apparently healthy subjects (139 +/- 32, 127 +/- 25, and 118 +/- 21 milliseconds, respectively; P < 0.01), whereas the E wave deceleration times (DT) were alike in both apparently healthy and unhealthy subjects. The diastolic and systolic components of the pulmonary venous blood flow were alike in apparently healthy and unhealthy subjects. Left atrial size was increased in all patients with disease, possibly indicating increased preload. CONCLUSION: In this population sample of elderly men, the commonly used E/A ratio did not distinguish between apparently healthy subjects and those with cardiovascular diseases such as CHD or hypertension, which are known to be associated with LV diastolic dysfunction in the middle-aged population. IVRT appeared to be the most sensitive of the Doppler-derived indices of LV diastolic function used in the present study, but for this variable, the differences between apparently healthy subjects and unhealthy subjects were small. Thus, the age-associated changes in LV compliance appear to override the impact of these disorders on indices of LV diastolic function in elderly populations.

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.

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.

Feasibility of obtaining pulmonary venous flow velocity in cardiac patients using transthoracic pulsed wave Doppler technique

The purpose of this study was to determine, in an adult population, the percentage of patients in whom high quality pulmonary venous flow velocity recordings can be obtained using current transthoracic pulsed wave Doppler techniques. Pulmonary venous and mitral flow velocity variables obtained with a pulsed wave Doppler method were used for the indirect assessment of left ventricular (LV) diastolic function and LV filling pressures. The general clinical use of these methods, however, remains uncertain because the transthoracic success rate of obtaining all components of pulmonary venous flow velocity has been variable, and sometimes reported to be as low as 30% to 60%. Mitral and pulmonary venous flow velocity variables were obtained using pulsed wave Doppler signals in 200 consecutive adult patients (mean age 68.2 +/- 11.4 years) in normal sinus rhythm who were referred for echocardiographic study. Six cardiac sonographers and five ultrasound systems were used. The success rate for obtaining pulmonary venous systolic and diastolic flow velocity was 95%, reverse flow velocity at atrial contraction was 90%, and the duration of reverse flow at atrial contraction was 89%. In the 5% to 11% of patients in whom pulmonary flow velocities could not be adequately recorded, the most common reasons were depth limitations of the pulsed wave Doppler machine, marked cardiac enlargement, or left atrial wall motion artifact. The success rate also was influenced by the ultrasound equipment used, individual variation among sonographers, and even the type (impaired, pseudonormal, restricted) of associated mitral filling pattern. Given current machine technology, sonographer education, and daily practice, high quality, complete recordings of pulmonary venous flow velocity can be obtained in approximately 90% of adult patients using the precordial transthoracic Doppler technique. These results suggest that using these variables as an aid for evaluating LV diastolic function and filling pressures may have broader clinical applicability than previously appreciated.