Characteristics of pulmonary artery pressure waveform for differential diagnosis of chronic pulmonary thromboembolism and primary pulmonary hypertension

Respiratory gating improves correlation between pulse wave transit time and pulmonary artery pressure in experimental pulmonary hypertension

Objective. Since pulse wave transit time (PWTT) shortens as pulmonary artery pressure (PAP) increases it was suggested as a potential non-invasive surrogate for PAP. The state of tidal lung filling is also known to affect PWTT independently of PAP. The aim of this retrospective analysis was to test whether respiratory gating improved the correlation coefficient between PWTT and PAP.Approach. In each one of five anesthetized and mechanically ventilated pigs two high-fidelity pressure catheters were placed, one directly behind the pulmonary valve, and the second one in a distal branch of the pulmonary artery. PAP was raised using the thromboxane A2 analogue U46619 and animals were ventilated in a pressure controlled mode (I:E ratio 1:2, respiratory rate 12/min, tidal volume of 6 ml kg-1). All signals were recorded using the multi-channel platform PowerLab®. The arrival of the pulse wave at each catheter tip was determined using a MATLAB-based modified hyperbolic tangent algorithm and PWTT calculated as the time interval between these arrivals.Main results. Correlation coefficient for PWTT and mean PAP wasr= 0.932 for thromboxane. This correlation coefficient increased considerably when heart beats either at end-inspiration (r= 0.978) or at end-expiration (r= 0.985) were selected (=respiratory gating).Significance. The estimation of mean PAP from PWTT improved significantly when taking the respiratory cycle into account. Respiratory gating is suggested to improve for the estimation of PAP by PWTT.

Exercise and pulsatile pulmonary vascular loading in chronic thromboembolic pulmonary disease

Chronic thromboembolic pulmonary disease (CTEPD) is characterized by organized nonresolving thrombi in pulmonary arteries (PA). In CTEPD with pulmonary hypertension (PH), chronic thromboembolic PH (CTEPH), early wave reflection results in abnormalities of pulsatile afterload and augmented PA pressures. We hypothesized that exercise during right heart catheterization (RHC) would elicit more frequent elevations of pulsatile vascular afterload than resistive elevations in patients with CTEPD without PH. The interdependent physiology of pulmonary venous and PA hemodynamics was also evaluated. Consecutive patients with CTEPD without PH (resting mean PA pressure ≤20 mmHg) undergoing an exercise RHC were identified. Latent resistive and pulsatile abnormalities of pulmonary vascular afterload were defined as an exercise mean PA pressure/cardiac output >3 WU, and PA pulse pressure to PA wedge pressure (PA PP/PAWP) ratio >2.5, respectively. Forty-five patients (29% female, 53 ± 14 years) with CTEPD without PH were analyzed. With exercise, 19 patients had no abnormalities (ExNOR), 26 patients had abnormalities (ExABN) of pulsatile (20), resistive (2), or both (4) elements of pulmonary vascular afterload. Exercise elicited elevations of pulsatile afterload (53%) more commonly than resistive afterload (13%) (p < 0.001). ExABN patients had lower PA compliance and higher pulmonary vascular resistance at rest and exercise and prolonged resistance-compliance time product at rest. The physiological relationship between changes in PA pressures relative to PAWP was disrupted in the ExABN group. In CTEPD without PH, exercise RHC revealed latent pulmonary vascular afterload elevations in 58% of patients with more frequent augmentation of pulsatile than resistive pulmonary vascular afterload.

A Comprehensive Assessment of Right Ventricular Function in Chronic Thromboembolic Pulmonary Hypertension

While chronic thromboembolic pulmonary hypertension (CTEPH) results from macroscopic and microscopic obstruction of the pulmonary vascular bed, the function of the right ventricle (RV) and increased RV afterload are the main determinants of its symptoms and prognosis. In this review, we assess RV function in patients diagnosed with CTEPH with a focus on the contributions of RV afterload and dysfunction to the pathogenesis of this disease. We will also discuss changes in RV function and geometry in response to treatment, including medical therapy, pulmonary endarterectomy, and balloon pulmonary angioplasty.

Right Ventricular Dyssynchrony in Patients With Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Arterial Hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are characterized by elevated pulmonary arterial pressure resulting in right heart failure. Right ventricular (RV) dyssynchrony may be associated with early-stage RV dysfunction; however, the differences in RV dyssynchrony between CTEPH and PAH and the factors contributing to RV dyssynchrony remain unclear.

METHODS AND RESULTS

Forty-four patients (CTEPH, 26; PAH, 18) were enrolled in this study. RV dyssynchrony was assessed by determining the standard deviation of the intervals from the peak QRS to peak systolic strain for 6 segments of the RV free and septal wall by using 2-dimensional speckle-tracking echocardiography (RV-6SD). The RV-6SD, pulmonary hemodynamics, echocardiographic findings, and patient demographics in CTEPH and PAH patients were compared and their correlations with RV-6SD were investigated. CTEPH patients were older and had significantly higher pulse pressure of the pulmonary artery (PP), tricuspid valve regurgitation pressure gradient, and RV-6SD, and lower pulmonary arterial compliance (PAC), despite showing comparable pulmonary arterial pressures. Age-adjusted multiple logistic analysis showed that RV-6SD and PAC were predictors of CTEPH rather than PAH. RV-SD6 was positively correlated with PP and RV dimension and negatively correlated with PAC.

CONCLUSIONS

CTEPH patients showed more evident RV dyssynchrony than PAH patients. Low PAC and a widened PP may delay RV free wall motion and cause RV dyssynchrony.

Surgical Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension is a progressive disease, which may lead to severe right ventricular dysfunction and debilitating symptoms. Pulmonary thromboendarterectomy (PTE) provides the best opportunity for complete resolution of obstructing thromboembolic disease and functional improvement in appropriately selected patients. In this article, the authors review preoperative workup, patient selection, operative technique, postoperative care, and outcomes after PTE.

Increased Pulmonary Arterial Compliance after Balloon Pulmonary Angioplasty Predicts Exercise Tolerance Improvement in Inoperable CTEPH Patients with Lower Pulmonary Arterial Pressure

BACKGROUND

Balloon pulmonary angioplasty (BPA) improved pulmonary arterial compliance (C_PA) and exercise tolerance in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).

OBJECTIVES

To investigate whether C_PA is a useful index to indicate exercise tolerance improvement by BPA in CTEPH patients.

METHODS

The correlation between changes in C_PA and improvements in 6-minute walk distance (6MWD) by BPA was retrospectively analyzed in 70 patients (Analysis 1), and it was sequentially analyzed in 46 symptomatic patients who achieved mean pulmonary arterial pressure (mPAP)<30mmHg (Analysis 2).

RESULTS

We enrolled 70 patients (female/male:57/13, mean age:59 years) who underwent a total of 352 BPA sessions which significantly increased C_PA (1.5±0.8 vs. 3.0±1.0 mL/mmHg) and decreased pulmonary vascular resistance (PVR) (8.0 ± 3.9 vs. 3.6 ± 1.7 wood units). The correlation coefficient between improvement in 6MWD and changes in PVR and C_PA were r=0.21 (p=0.09) and r=0.14 (p=0.26) (Analysis 1). In Analysis 2, those were r=0.32 (p=0.06) and r=0.38 (p=0.02), respectively.

CONCLUSIONS

C_PA can be a useful index to indicate the improvement in exercise tolerance by BPA in symptomatic patients with lower mPAP.

The physiologic basis of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare dyspnea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance (PVR) and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodeling, lung function in PAH is generally well preserved, with hyperventilation and increased physiologic dead space, but minimal changes in lung mechanics and only mild to moderate hypoxemia and hypocapnia. Hypoxemia is mainly caused by a low mixed venous PO₂ from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for hematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency-domain or in the time-domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-PA coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction.

Wave Reflection at the Origin of a First-Generation Branch Artery and Target Organ Protection: The AGES-Reykjavik Study

[Figure: see text].

Influence of coupled hemodynamics-arterial wall interaction on compliance in a realistic pulmonary artery with variable intravascular wall properties

Pulmonary hypertension is characterized by elevation of pulmonary artery (PA) pressure (p) and structural remodeling of the PA wall, leading to reduction in arterial compliance (c). As a step towards improving diagnosis of pulmonary disease, we use the PA branch geometry (main pulmonary artery (MPA) branching into left (LPA) and right (RPA) pulmonary arteries) obtained from MRI in conjunction with an inverse algorithm to obtain the pre-stress level in the artery walls. Next, a coupled blood-wall interaction (BWI) calculation provides hemodynamic information as well as compliance of the PA walls. We show that the computed load-free geometry from the inverse algorithm exhibits a 27.8% lower inner diameter (d) and 18.5% lower outer d compared to the in vivo geometry from MRI. Further, the mean p computed from the BWI computation in the main PA (p_MPA-n) is within 4% of the mean p_MPA-e (n-numerical; e-experimental). Also, the mean Q computed in the left PA (Q_LPA-n) is within 10% of the mean Q_LPA-e. Finally, the compliance c_MPA-n is computed to be 27% lower than c_MPA-e, while the c_LPA-n is computed to be 20.4% lower than c_LPA-e. Importantly, the PA shows significant intra-vascular variation in compliance, with the MPA showing higher overall compliance compared to the LPA (3.5-4 times).

Proximal pressure reducing effect of wave reflection in the pulmonary circulation disappear in obstructive disease: insight from a rabbit model

Locating the site of increased resistance within the vascular tree in pulmonary arterial hypertension could assist in both patient diagnosis and tailoring treatment. Wave intensity analysis (WIA) is a wave analysis method that may be capable of localizing the major site of reflection within a vascular system. We investigated the contribution of WIA to the analysis of the pulmonary circulation in a rabbit model with animals subjected to variable occlusive pulmonary disease. Animals were embolized with different sized microspheres for 6 wk ( n = 10) or underwent pulmonary artery (PA) ligation for 6 wk ( n = 3). These animals were compared with a control group ( n = 6) and acutely embolized animals ( n = 4). WIA was performed and compared with impedance-based methods to analyze wave reflections. The control group showed a relatively high extent of reflected waves (15.7 ± 10.6%); reflections had a net effect of pressure reduction during systole, suggesting an open-end reflector. The pattern of wave reflection was not different in the group with partial PA ligation (12.4 ± 4.1%). In the chronically embolized group, wave reflection was not observed (3.6 ± 1.5%). In the acute embolization group, wave reflection was more prominent (37.3 ± 12.6%), with the appearance of a novel wave increasing pressure, suggesting the appearance of a closed-end reflector. Wave reflections of an open-end type are present in the normal rabbit pulmonary circulation. However, the pattern and nature of reflections vary according to the extent of pulmonary vascular occlusion.

NEW & NOTEWORTHY The study proposes an original framework of a complementary analysis of wave reflections in the time domain and in the frequency domain. The methodology was used in the pulmonary circulation with different forms of chronic obstructions. The results suggest that the pulmonary vascular tree generates a reflection pattern that could actually assist the heart during ejection, and chronic obstruction significantly modifies the pattern.

Poor Subpleural Perfusion Predicts Failure After Balloon Pulmonary Angioplasty for Nonoperable Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Poor subpleural perfusion (PSP) in the capillary phase of pulmonary angiography predicts worse outcomes following pulmonary endarterectomy in operable chronic thromboembolic pulmonary hypertension (CTEPH). Balloon pulmonary angioplasty (BPA) has emerged as a treatment for nonoperable CTEPH. The goal of the present article was to assess the association between PSP and BPA failure.

METHODS

Subpleural perfusion was classified as poor (defined as subpleural spaces either not perfused or minimally perfused in all segments) or normal. We retrospectively reviewed PSP and hemodynamic variables of 101 consecutive patients who underwent BPA from February 2014 to August 2016. The total cross-sectional area of bronchial arteries was also measured by using CT scanning. Patients were categorized according to hemodynamic results after the last BPA: a failure group (defined as mean pulmonary arterial pressure > 30 mm Hg and a decrease in pulmonary vascular resistance < 30% [n = 15]) or a success group (n = 86).

RESULTS

Although baseline hemodynamic variables were similar between the two groups, PSP was observed in 46.7% of patients in the failure group vs 13.9% in the success group (P = .003). Multivariate analysis revealed that PSP was the only predictor of BPA failure (OR, 4.02 [95% CI, 1.17-13.89]; P = .028). Patients with PSP exhibited poorly developed bronchial arteries compared with patients with normal perfusion (7.0 [5.8-9.6] mm² vs 8.7 [6.9-11.3] mm²; P = .032).

CONCLUSIONS

PSP in the capillary phase, suggesting the presence of small vessel disease with diffuse distal thrombosis, is a predictor of BPA failure. PSP was also associated with less developed bronchial arteries, which suggests a key role of bronchial-pulmonary anastomoses in maintaining the pulmonary capillary bed open downstream of the pulmonary arterial obstruction. PSP affected approximately 15% of patients with nonoperable CTEPH who underwent BPA.

Combined oral administration of L-arginine and tetrahydrobiopterin in a rat model of pulmonary arterial hypertension

Alterations in the nitric oxide (NO) pathway play a major role in pulmonary arterial hypertension (PAH). L-arginine (LA) and tetrahydrobiopterin (BH₄) are main substrates in the production of NO, which mediates pulmonary vasodilation. Administration of either LA or BH₄ decrease pulmonary artery pressure (PAP). A combined administration of both may have synergistic effects in the therapy of PAH. In a telemetrically monitored model of unilateral pneumonectomy and monocrotaline-induced PAH, male Sprague-Dawley rats received either LA (300 mg/kg; n = 15), BH₄ (20 mg/kg; n = 15), the combination of LA and BH₄ (300 mg/kg, 20 mg/kg; n = 15), or vehicle (control group; n = 10) from day 28 after monocrotaline induction. Therapy was orally administered once daily over consecutive 14 days. LA, BH₄, or both equally lowered PAP, increased pulmonary vascular elasticity, restored spontaneous locomotoric activity, prevented body weight loss and palliated small vessel disease of severely pulmonary hypertensive rats. BH₄ substitution lowered asymmetric dimethylarginine levels sustainably at 60 min after administration and downregulated endothelial NO synthase mRNA expression. No significant survival, macro- and histomorphologic or hemodynamic differences were found between therapy groups at the end of the study period. Administration of LA and BH₄ both mediated a decrease of mean PAP, attenuated right ventricular hypertrophy and small vessel disease in monocrotaline-induced pulmonary hypertensive rats, though a combined administration of both substances did not reveal any synergistic therapy effects in our animal model.

Development of a servo pump system for in vivo loading of pathological pulmonary artery impedance on the right ventricle of normal rats

Pulmonary artery (PA) impedance provides detailed information on right ventricular (RV) afterload in pulmonary hypertension (PH). This study aimed to examine PA impedance in a rat model of monocrotaline-induced PH (MCT-PH) and to develop an experimental system for in vivo loading of pathological PA impedance on the RV of normal rats. PA impedance was quantified in normal ( n = 10) and MCT-PH rats ( n = 10) using a three-element Windkessel (3-WK) model. Compared with normal rats, MCT-PH rats had higher characteristic impedance ( ZC) and peripheral pulmonary resistance ( RP) ( ZC: 0.121 ± 0.039 vs. 0.053 ± 0.017 mmHg·min·ml−1, P < 0.001; RP: 0.581 ± 0.334 vs. 0.252 ± 0.105 mmHg·min·ml−1, P = 0.013) and lower pulmonary artery compliance ( CP) (0.242 ± 0.131 vs. 0.700 ± 0.186 ml/mmHg, P < 0.001). In another group of 10 normal rats, a computer-controlled servo pump was connected to the left PA for loading PA impedance with parameters in pathological ranges designed by the 3-WK model. Activation of the servo pump decreased the error of measured vs. target PA impedance (modulus: from 0.047 ± 0.020 without pump activation to 0.019 ± 0.007 with pump activation, P < 0.001; phase: 0.085 ± 0.028 to 0.043 ± 0.012 radians, P < 0.001). In conclusion, MCT-PH increases ZCand RPand decreases CP. Our servo pump system, which is capable of imposing arbitrary PA impedance with pathological parameters, may offer a unique opportunity to delineate the pathological significance of PA impedance in PH.

Mean Pulmonary Artery Pressure Using Echocardiography in Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Mean pulmonary arterial pressure (MPAP) is an important pulmonary hemodynamic parameter used in the management of patients with chronic thromboembolic pulmonary hypertension (CTEPH). We compared echocardiography-derived estimates of MPAP with right heart catheterization (RHC) to identify reliable noninvasive methods of estimating MPAP-derived RHC (MPAPRHC) in these patients.

METHODS AND RESULTS

Echocardiography and RHC were performed in 56 patients with CTEPH (60.5±12.0 years; 44 females). We measured the tricuspid regurgitation (TR) pressure gradient (TRPG) using echocardiography. The mean systolic right ventricular (RV)-right atrial (RA) gradient was calculated by tracing the TR time velocity flow. Systolic and mean pulmonary artery pressures (SPAPTRand MPAPTR) estimated from TRPG and mean systolic RV-RA gradient were calculated by adding RA pressure based on the inferior vena cava. MPAPChemlawas calculated using Chemla's formula: 0.61×SPAPTR+2 mmHg. MPAPRHCand pulmonary vascular resistance were 35.9±11.3 mmHg and 6.6±3.6 Wood units, respectively. The mean difference from MPAPRHCand limits of agreement were -1.5 mmHg and -19.6 to 16.5 mmHg for MPAPTR, and -4.6 mmHg and -24.5 to 15.2 mmHg for MPAPChemla. Accuracy within 10 mmHg and 5 mmHg of MPAPRHCwas 80.4% and 46.4% for MPAPTR, and 71.4% and 48.2% for MPAPChemla, respectively.

CONCLUSIONS

MPAPTRand MPAPChemlaare reliable estimates for MPAPRHCin patients with CTEPH. (Circ J 2016; 80: 1259-1264).

Wave reflections in the pulmonary arteries analysed with the reservoir-wave model

Conventional haemodynamic analysis of pressure and flow in the pulmonary circulation yields incident and reflected waves throughout the cardiac cycle, even during diastole. The reservoir-wave model provides an alternative haemodynamic analysis consistent with minimal wave activity during diastole. Pressure and flow in the main pulmonary artery were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading and positive end-expiratory pressure were observed. The reservoir-wave model was used to determine the reservoir contribution to pressure and flow and once subtracted, resulted in 'excess' quantities, which were treated as wave-related. Wave intensity analysis quantified the contributions of waves originating upstream (forward-going waves) and downstream (backward-going waves). In the pulmonary artery, negative reflections of incident waves created by the right ventricle were observed. Overall, the distance from the pulmonary artery valve to this reflection site was calculated to be 5.7 ± 0.2 cm. During 100% O2 ventilation, the strength of these reflections increased 10% with volume loading and decreased 4% with 10 cmH2O positive end-expiratory pressure. In the pulmonary arterial circulation, negative reflections arise from the junction of lobar arteries from the left and right pulmonary arteries. This mechanism serves to reduce peak systolic pressure, while increasing blood flow.

Partitioning pulmonary vascular resistance using the reservoir-wave model

The conventional determination of pulmonary vascular resistance does not indicate which vascular segments contribute to the total resistance of the pulmonary circulation. Using measurements of pressure and flow, the reservoir-wave model can be used to partition total pulmonary vascular resistance into arterial, microcirculation, and venous components. Changes to these resistance components are investigated during hypoxia and inhaled nitric oxide, volume loading, and positive end-expiratory pressure. The reservoir-wave model defines the pressure of a volume-related reservoir and the asymptotic pressure. The mean values of arterial and venous reservoir pressures and arterial and venous asymptotic pressures define a series of resistances between the main pulmonary artery and the pulmonary veins: the resistance of large and small arteries, the microcirculation, and veins. In 11 anaesthetized, open-chest dogs, pressure and flow were measured in the main pulmonary artery and a single pulmonary vein. Volume loading reduced each vascular resistance component, whereas positive end-expiratory pressure only increased microcirculation resistance. Hypoxia increased the resistance of small arteries and veins, whereas nitric oxide only decreased small-artery resistance significantly. The reservoir-wave model provides a novel method to deconstruct total pulmonary vascular resistance. The results are consistent with the expected physiological responses of the pulmonary circulation and provide additional information regarding which segments of the pulmonary circulation react to hypoxia and nitric oxide.

Relation of coronary flow reserve and diastolic function to fractional pulse pressure in hypertensive patients

Fractional pulse pressure (PPf), is thought to more directly reflect arterial stiffness than pulse pressure. Our aim was to evaluate the relationship between coronary flow reserve (CFR), left ventricular diastolic function (LVDf) and PPf in hypertensive patients with normal coronary arteries. Out of 109 hypertensive patients (aged 52.8 ± 9.4 years), with normal coronary angiography, CFR was calculated successfully in 106 patients. CFR was calculated using transthoracic echo Doppler assessment with hyperemia induced by infusion of dipyridamole at a rate of 0.56 mg/kg over 4 minutes, while diastolic function was evaluated by means of transmitral flow and tissue Doppler imaging. PPf was calculated as pulse pressure divided by mean arterial pressure [Systolic blood pressure - Diastolic blood pressure/Mean arterial pressure (SBP - DBP/MAP)], Hypertensive patients with low CFR (n = 54) compared with those with normal CFR (n = 52) exhibited significantly increased PPf (75.2 ± 11.4 vs. 61.5 ± 6.7 P < 0.001). Moreover, patients with higher PPf had significantly decreased transmitral E/A ratio (P < 0.01), as well as increased E/Em ratio (P < 0.01). In hypertensives with low CFR, PPf was negatively correlated with CFR (r = -0.815, P < 0.0001). After applying multivariate linear regression analysis, PPf turned out to be a powerful independent predictor of CFR. Receiver operating characteristic (ROC) analysis revealed that a PPf of ≥0.63 was the best cutoff value for prediction of CFR <2.0 and E/Em ≥ 8 (AUC = 0.916 and 0.929 respectively; P < 0.001). Increased PPf was associated with impaired CFR and diastolic dysfunction in hypertensive patients with normal coronary arteries. PPf could be used as a simple non-invasive index for assessment of coronary microcirculation in hypertensives with normal coronary arteries.

Proximal pulmonary arterial obstruction decreases the time constant of the pulmonary circulation and increases right ventricular afterload

The time constant of the pulmonary circulation, or product of pulmonary vascular resistance (PVR) and compliance (Ca), called the RC-time, has been reported to remain constant over a wide range of pressures, etiologies of pulmonary hypertension, and treatments. We wondered if increased wave reflection on proximal pulmonary vascular obstruction, like in operable chronic thromboembolic pulmonary hypertension, might also decrease the RC-time and thereby increase pulse pressure and right ventricular afterload. Pulmonary hypertension of variable severity was induced either by proximal obstruction (pulmonary arterial ensnarement) or distal obstruction (microembolism) eight anesthetized dogs. Pulmonary arterial pressures (Ppa) were measured with high-fidelity micromanometer-tipped catheters, and pulmonary flow with transonic technology. Pulmonary ensnarement increased mean Ppa, PVR, and characteristic impedance, decreased Ca and the RC-time (from 0.46 ± 0.07 to 0.30 ± 0.03 s), and increased the oscillatory component of hydraulic load (Wosc/Wtot) from 25 ± 2 to 29 ± 2%. Pulmonary microembolism increased mean Ppa and PVR, with no significant change in Ca and characteristic impedance, increased RC-time from 0.53 ± 0.09 to 0.74 ± 0.05 s, and decreased Wosc/Wtot from 26 ± 2 to 13 ± 2%. Pulse pressure increased more after pulmonary ensnarement than after microembolism. Concomitant measurements with fluid-filled catheters showed the same functional differences between the two types of pulmonary hypertension, with, however, an underestimation of Wosc. We conclude that pulmonary hypertension caused by proximal vs. distal obstruction is associated with a decreased RC-time and increased pulsatile component of right ventricular hydraulic load.

Pulmonary vascular wall stiffness: An important contributor to the increased right ventricular afterload with pulmonary hypertension

Pulmonary hypertension (PH) is associated with structural and mechanical changes in the pulmonary vascular bed that increase right ventricular (RV) afterload. These changes, characterized by narrowing and stiffening, occur in both proximal and distal pulmonary arteries (PAs). An important consequence of arterial narrowing is increased pulmonary vascular resistance (PVR). Arterial stiffening, which can occur in both the proximal and distal pulmonary arteries, is an important index of disease progression and is a significant contributor to increased RV afterload in PH. In particular, arterial narrowing and stiffening increase the RV afterload by increasing steady and oscillatory RV work, respectively. Here we review the current state of knowledge of the causes and consequences of pulmonary arterial stiffening in PH and its impact on RV function. We review direct and indirect techniques for measuring proximal and distal pulmonary arterial stiffness, measures of arterial stiffness including elastic modulus, incremental elastic modulus, stiffness coefficient β and others, the changes in cellular function and the extracellular matrix proteins that contribute to pulmonary arterial stiffening, the consequences of PA stiffening for RV function and the clinical implications of pulmonary vascular stiffening for PH progression. Future investigation of the relationship between PA stiffening and RV dysfunction may facilitate new therapies aimed at improving RV function and thus ultimately reducing mortality in PH.

Diagnosis and assessment of pulmonary vascular disease by Doppler echocardiography

Pulmonary hypertension (PH) is a relatively misunderstood disease, partly related to the fact that many perceive PH to be a singular diagnosis. An unintended consequence of this is the misapplication of the role of the Doppler-Echocardiographic (DE) examination, as well as an underappreciation for its ability to help discern PH pathophysiology prior to right heart catheterization. Since DE often serves as the "gatekeeper" to invasive right heart catheterization, misinterpretation of the DE can lead to missed or delayed diagnosis with devastating consequences. Too often, the primary or nearly exclusive focus of the DE examination is placed on the pulmonary artery pressure estimation. Two main issues with this approach are that Doppler pressure estimations can be inaccurate and even when accurate, without integration of additional 2-D and Doppler information, the clinician will often still not appreciate the pathophysiology of the PH nor its clinical significance. This review will focus on the 2-D and Doppler features necessary to assess pulmonary vascular disease (PVD), discern the salient differences between PVD and pulmonary venous hypertension (PVH), and how to integrate these key DE parameters such that PH pathophysiology can be determined noninvasively and early in the patient workup. Overreliance on any single DE metric, and especially PA pressure estimation, detracts from the overall diagnostic potential of the DE examination. Integrating the relative balance of right and left heart findings, along with proper Doppler interpretation provides a wealth of clinical and pathophysiologic insight prior to invasive hemodynamic assessment. The end results are heightened awareness and improved identification of which patients should be referred for further invasive testing, as well the use of the DE information to compliment the findings from invasive testing.

Assessment of right ventricular afterload by pressure waveform analysis in acute pulmonary hypertension

AIM

To characterize hydraulic right ventricle (RV) afterload by pulmonary arterial pressure waveform analysis in an acute pulmonary hypertension (PH) model.

METHODS

Pulmonary artery (PA) flow and pressure were recorded in six anesthetized sheep. Acute isobaric PH was induced by phenylephrine (active) and PA mechanical constriction (passive). We estimated the amplitude of the forward and reflected pressure waves according to the inflection point. In most cases the inflection pressure was smooth, thus the inflection point was defined as the time at which the first derivative of pulmonary arterial pressure reached its first minimum. We calculated the input and characteristic (Z(C), time-domain Li method) impedances, the capacitance index (stroke volume/pulse pressure), the augmentation index (AI) (reflected pressure/pulse pressure), the fractional pulse pressure (pulse pressure/mean pressure) and the wasted energy generated by the RV due to wave reflection during ejection (E(W)).

RESULTS

Pulse pressure, fractional pulse pressure, AI and Z(C) increased and capacitance index decreased during passive PH with respect to control (P < 0.05). In contrast, Z(C) and the capacitance index did not change and E(W) and the AI decreased during active PH. Pulse pressure correlated with E(W) and Z(C) and the AI was correlated with E(W) (r > 0.6, P < 0.05).

CONCLUSION

PA pressure waveform analysis allows the quantification of the dynamic RV afterload. Prospective clinical studies will be necessary to validate this time-domain approach to evaluate the dynamic RV afterload in chronic PH.

Hemodynamic assessment of pulmonary hypertension

There has been significant progress in our understanding of the pathobiology, epidemiology and prognosis of pulmonary vascular disease and, over the past few years, there has been an explosion of clinical therapeutic trials for pulmonary arterial hypertension (PAH). The increasing number of different conditions now associated with PAH and the appearance of new diagnostic techniques have led to a need for a systematic diagnostic approaches and a new disease classification, which has resulted in notable improvements in the quality and efficacy of clinical care. We appreciate traditional resting right heart catheterization techniques (which still remain the gold standard for diagnosing PAH and managing patients on therapy) and look forward to novel invasive techniques (e.g. intravascular ultrasound) that add greatly to our understanding of right ventricle and pulmonary circulation, and for the interpretation of data from clinical trials as well.

Are pulmonary artery pulsatility indexes able to differentiate chronic pulmonary thromboembolism from pulmonary arterial hypertension? An echocardiographic and catheterization study

The differentiation between chronic pulmonary thromboembolic hypertension (CTEPH) and pulmonary arterial hypertension (PAH) remains a clinical challenge. The aim of our study was to evaluate the usefulness of both echocardiographically and invasively derived pulmonary artery pulsatility indexes in the etiologic differentiation of patients with CTEPH and PAH. We retrospectively analyzed the results of echocardiographic and invasive hemodynamic examinations in 125 patients with either CTEPH (n = 62) or PAH (n = 63). Invasive data were obtained in 52 patients with CTEPH and 43 PAH patients. Using echocardiography, pulmonary artery systolic (PASP), diastolic (PADP) and mean (PAMP) pressures were estimated from velocities of tricuspid regurgitation and pulmonary regurgitation, respectively. Pulse pressure (PP) was calculated as the difference between PASP and PADP. To obtain pulmonary artery pulsatility indexes, we normalized PP by PASP (PP/PASP), by PAMP (PP/PAMP) and by PADP (PP/PADP). Pulsatility indexes assessed by echocardiography did not differ between CTEPH and PAH patients except for PP/PAMP [PP/PAMP (1.82 ± 0.33 vs. 1.40 ± 0.3, p < 0.001)]. Invasively derived pulsatility indexes were significantly higher in subjects with CTEPH (0.60 ± 0.08 vs. 0.53 ± 0.09 for PP/PASP; 0.98 ± 0.21 vs. 0.81 ± 0.21 for PP/PAMP; 1.58 ± 0.52 vs. 1.21 ± 0.41 for PP/PADP; all p < 0.001). The areas under the receiver-operating characteristic curves analysis showed that no cutoff value allowed discriminating between CTEPH and PAH by using echocardiographically or invasively derived pulsatility indices. Invasively derived pulmonary artery pulsatility indexes as well as echocardiographically determined PP/PAMP indexes are higher in CTEPH compared to PAH. However, due to the important overlap no optimal threshold values of these parameters can be given to allow satisfactory discrimination of the two diseases in clinical practice.

The effect of oxygenator mechanical characteristics on energy transfer during clinical cardiopulmonary bypass

The hollow-fibre oxygenator is a key component of any extracorporeal circuit used to provide cardiopulmonary bypass (CPB) during open-heart surgery. Since the oxygenator is placed downstream of the pump, the energy losses over it have a direct impact on the quality of pulsatile pressure and flow waveforms. The objective of this study was to describe the effects of hydrodynamic characteristics of the oxygenator on energy transfer during pulsatile, normothermic CPB. Twenty-three adult patients scheduled for coronary bypass surgery were divided randomly into two groups, using either an oxygenator (Group 1) with a relatively high-resistance and low-compliance (2079 ± 148 dyn.s.cm(-5) and 0.00348 ± 0.00071 ml.mmHg(-1), respectively) or an oxygenator (Group 2) with a relatively low-resistance and high-compliance (884 ± 464 dyn.s.cm(-5) and 0.01325 ± 0.00161 ml.mmHg(-1), respectively). During perfusion, pre- and post-oxygenator pressures, radial artery pressure, and blood flow were recorded simultaneously. A 32% decline of mean pressure was observed in Group 1 and a 16% decline in Group 2 (p<0.0001). Another decrease by approximately 73% in mean pressure in the rest of the perfusion system was noted in both groups. The mean radial artery pressure did not differ between the groups (74 ± 6 mmHg in Group 1 and 73 ± 6 mmHg in Group 2, p=0.608). Although lower total energy transfer indices were noticed through the low-resistance oxygenator (Group 2), both oxygenators showed a decrease of the generated pump oscillatory energy of approximately 50%. Despite the differences in resistance and compliance of the hollow-fibre oxygenators used, both oxygenators cause a comparable loss of generated oscillatory energy. Exclusion of the oxygenator downstream of the pulsatile pump would improve energy transfer during CPB.

Is pulse pressure a predictor of new-onset diabetes in high-risk hypertensive patients?: a subanalysis of the Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial

OBJECTIVE

Hypertensive patients have an increased risk of developing diabetes. Accumulating evidence suggests a close relation between metabolic disturbance and increased arterial stiffness. Here, we examined the association between pulse pressure and the risk of new-onset diabetes in high-risk Japanese hypertensive patients.

RESEARCH DESIGN AND METHODS

The Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial examined the effects of candesartan and amlodipine on the incidence of cardiovascular events in 4,728 high-risk Japanese hypertensive patients. In the present study, we analyzed the relationship between pulse pressure at baseline and new-onset diabetes in 2,685 patients without diabetes at baseline (male 1,471; mean age 63.7 years; mean BMI 24.8 kg/m(2)) as a subanalysis of the CASE-J trial.

RESULTS

During 3.3 +/- 0.8 years of follow-up, 97 patients (3.6%) developed diabetes. In multiple Cox regression analysis, pulse pressure was an independent predictor for new-onset diabetes (hazard ratio [HR] per 1 SD increase 1.44 [95% CI 1.15-1.79]) as were male sex, BMI, and additional use of diuretics, whereas age and heart rate were not. Plots of HRs for new-onset diabetes considering both systolic and diastolic blood pressure (DBP) revealed that a higher pulse pressure with a lower DBP, indicating that the increased pulse pressure was largely due to increased arterial stiffness, was strongly associated with the risk of new-onset diabetes.

CONCLUSIONS

Pulse pressure is an independent predictor of new-onset diabetes in high-risk Japanese hypertensive patients. Increased arterial stiffness may be involved in the development of diabetes.

Impact of the metabolic syndrome on aortic pulse pressure and ascending aortic pulsatility in patients with angiographically normal coronary arteries

BACKGROUND

Large artery stiffness is a major determinant of pulse pressure (PP), and PP at baseline has been associated with future coronary events.

OBJECTIVE

To evaluate the impact of the metabolic syndrome on aortic PP and ascending aortic pulsatility (AP) in patients with angiographically normal coronary arteries.

METHODS

Forty-two patients with the metabolic syndrome and 40 age matched control subjects without the metabolic syndrome were included in the study. All subjects had normal coronary arteries. Diagnosis of the metabolic syndrome was based on the International Diabetes Federation guidelines published in 2005. Ascending AP was estimated as the ratio of aortic PP to mean blood pressure.

RESULTS

Aortic PP (59+/-12 mmHg versus 43+/-10 mmHg; P<0.001) and ascending AP (0.54+/-0.10 versus 0.48+/-0.10; P<0.001) were significantly higher in the metabolic syndrome group. Multiple regression analysis revealed statistically independent relationships between ascending AP and fasting blood glucose, waist circumference and systolic blood pressure (model R2=0.408; P<0.001). The metabolic syndrome, as a whole, was also independently associated with both ascending AP (P<0.01) and aortic PP (P<0.01).

CONCLUSION

The data showed that the metabolic syndrome is independently associated with increased aortic PP and ascending AP in patients with normal coronary arteries, suggesting aortic stiffness as one of the possible mechanisms underlying the excess cardiovascular risk associated with the metabolic syndrome.

How to measure pulmonary vascular and right ventricular function

Long-standing pulmonary hypertension causes significant peripheral and proximal arterial remodeling and right ventricular dysfunction. The clinical metric most often used to assess the progression of PH is the pulmonary vascular resistance (PVR). However, even when measured from multipoint pressure-flow curves, PVR provides information only on the peripheral arterial function, not the proximal arterial function and gives only an incomplete description of all the forces that oppose right ventricular (RV) flow output. Pulmonary vascular impedance spectra (PVZ) capture the impact of proximal and peripheral arterial structure and function on RV function. Analyses of ventricular-vascular coupling give insight into the efficiency of mechanical and metabolic interactions between the right ventricle and the pulmonary vasculature. Here we review techniques for measuring PVZ in humans and animal models and for determining RV function.

Chronic thromboembolic and pulmonary arterial hypertension share acute vasoreactivity properties

BACKGROUND

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are the major classes of pulmonary hypertensive disorders according to the World Health Organization; both lead to right heart failure and death. A better understanding of disease mechanisms has led to the suggestion that the thromboembolic and nonthromboembolic types of pulmonary hypertension may share pathophysiologic features. We therefore compared acute vasoreactivity and proximal pulmonary artery compliance in patients with PAH and CTEPH during the initial diagnostic heart catheterization.

METHODS

Right heart catheterization using a flow-directed Swan-Ganz catheter was performed in patients with CTEPH (n = 22) and PAH (n = 35). Pulmonary hemodynamics were assessed at baseline, during the inhalation of 40 ppm of nitric oxide, and 30 min after the inhalation of 10 mug of iloprost. To assess the proximal pulmonary artery compliance, the pulse pressure (PP) [systolic-diastolic pressure] and the fractional PP (PPf) [divided by the mean pressure] were calculated.

RESULTS

Both vasodilators produced similar hemodynamic improvement, and the difference between CTEPH and PAH was not significant. The baseline PP and PPf did not vary between the two groups.

CONCLUSION

Patients with PAH and CTEPH show similar acute vasoreactivity to inhaled nitric oxide and iloprost, and have similar pulmonary artery compliance. These findings support the presence of some shared pathophysiologic pathways in both disorders and may lead to therapeutic implications in patients with inoperable CTEPH.

Echocardiography in Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a significant complication of venous thromboembolism and is caused by incomplete resolution of pulmonary emboli. The persistent chronic pulmonary hypertension leads to right-ventricle pressure overload. As a result, there is often significant functional and morphological alteration of both the right and the left ventricle. Transthoracic echocardiography, which allows for the estimation of pulmonary arterial pressures, not only plays an important role in the diagnosis of pulmonary hypertension but also provides insights in the pathophysiology of CTEPH. This article reviews the echocardiographic techniques and findings in CTEPH patients.

Anaesthesia management for pulmonary endarterectomy

PURPOSE OF REVIEW

Options for the surgical treatment of chronic thromboembolic pulmonary hypertension are either lung transplantation or pulmonary endarterectomy. Pulmonary endarterectomy is considered permanently curative and the treatment of choice. The procedure dramatically improves functional status and provides an excellent immediate and long-term survival, much better than transplantation. Pulmonary endarterectomy, until recently performed in only a few highly specialized centres, is now spreading worldwide with good results. This review will focus on the understanding of the pathophysiology of the disease and on recent advances in assessment and treatment strategies.

RECENT FINDINGS

Recent data reinforce the thromboembolic nature of chronic thromboembolic pulmonary hypertension, and have shown that the disorder is more common than was thought and remains underdiagnosed. There has recently been a remarkable surge in the understanding of the mechanisms involved in the pathogenesis of pulmonary hypertension. Advances in diagnosis, surgical techniques, preoperative treatment, and perioperative management have improved the prognosis of this debilitating disease. New information about pretreatment and medical treatment with prostanoids and endothelin receptor antagonists is now available.

SUMMARY

Pulmonary endarterectomy can be successfully performed in selected centres using a multidisciplinary approach involving the specialities of surgery, pulmonary medicine, cardiology, radiology, anaesthesiology and critical care medicine. The largest risk factor remains the degree of operability related to a high pulmonary vascular resistance caused by permanent changes in the pulmonary vascular bed. Early operation is now recommended to prevent these irreversible changes. Further investigations are warranted to establish the role of new drugs in surgical patients with chronic thromboembolic pulmonary hypertension.

Portopulmonary hypertension: hemodynamics, pulmonary angiography, and configuration of the heart

BACKGROUND

The goal of the present study was to examine the cardiac configuration and pulmonary vascular changes in patients with portopulmonary hypertension (PPHTN) and compare them with those of idiopathic pulmonary arterial hypertension (IPAH).

METHODS AND RESULTS

The subjects were 10 patients with PPHTN and 18 with IPAH. In PPHTN, the increases in the right ventricular end-diastolic volume index (89+/-19 vs 128+/-50 ml/m2; p=0.04), right end-systolic volume index (50+/-19 vs 95+/-47 ml/m 2; p=0.02) and right ventricular mass index (47+/-18 g/m2 vs 79+/-31; p=0.04) were low compared with IPAH. The decrease in the right ventricular ejection fraction was also low in PPHTN (45+/-10 vs 28+/-13%; p=0.01). The degree of sparse arborization and abrupt narrowing on wedged pulmonary angiography was moderate in PPHTN compared with IPAH. In PPHTN, the proximal pulmonary arteries were dilated near the segmental arteries, which were narrow in IPAH.

CONCLUSION

Changes in the configuration of the heart were moderate in PPHTN compared with those in IPAH. The degree of sparse arborization and abrupt narrowing were also moderate in PPHTN.

Efficacy of acute inhalation of nitric oxide in patients with primary pulmonary hypertension using chronic use of continuous epoprostenol infusion

BACKGROUND

There have only been a few reports published on combination therapy for patients with primary pulmonary hypertension (PPH).

METHODS AND RESULTS

Fifteen patients with PPH (4 men and 11 women, 34.5+/-12.1 years old) had received chronic administration of epoprostenol and the additive effects of inhaled nitric oxide (NO) and the hemodynamic changes were evaluated. In addition, the difference in the effect of acute NO loading before and after the epoprostenol therapy was compared in 6 of these patients. Under chronic use of epoprostenol, mean pulmonary arterial pressure, mean right atrial pressure and pulmonary vascular resistance were decreased with acute inhalation of NO. However, cardiac output, mean aortic pressure and systemic vascular resistance were unchanged. As a result, the pulmonary to systemic vascular resistance ratio was reduced. Moreover, after chronic use of epoprostenol, the change (delta) in cardiac output with NO inhalation was increased and the NO-induced decrease in pulmonary vascular resistance was augmented compared to those before the induction.

CONCLUSION

Nitric oxide inhalation further improved the hemodynamics when combined with chronic use of epoprostenol in PPH patients. These results suggest the possibility that combination therapies can be used in the treatment for PPH patients.

Echocardiography in pulmonary vascular disease

The assessment of pulmonary artery pressure, right ventricular function, right ventricular filling pressure, and tricuspid regurgitation provides invaluable information in the care of patients with pulmonary vascular disease. Echocardiography provides a rapid, noninvasive, portable, and accurate method to evaluate these parameters and also provides information on left ventricular and valvular function. Echocardiography has therefore become one of the most commonly performed diagnostic studies in patients with pulmonary vascular disease, and the technique's applications in this area are likely to grow. This article presents an overview of the current uses of echocardiography in pulmonary vascular disease and pulmonary hypertension.

Feasibility of Routine Pulmonary Arterial Impedance Measurements in Pulmonary Hypertension

OBJECTIVES

Right ventricular (RV) afterload is best described by a pulmonary arterial impedance (PVZ) spectrum, which integrates pulmonary vascular resistance (PVR), elastance, and wave reflection. We evaluated the feasibility of PVZ determinations in patients with pulmonary arterial hypertension (PAH) during routine right heart catheterization and Doppler echocardiography.

DESIGN

Prospective study.

SETTING

Academic hospital.

PATIENTS

Twenty-two patients with PAH.

INTERVENTIONS

Right heart catheterization with a fluid-filled Swan-Ganz catheter, Doppler echocardiography, and administration of inhaled nitric oxide (NO) [10 to 20 ppm; 17 patients], maximum tolerated dose of IV epoprostenol (average, 8.5 ng/kg/min; 5 patients), and IV dobutamine (8 micro g/kg/min; 8 patients).

MEASUREMENTS AND RESULTS

PVZ was calculated from the spectral analysis of synchronized pulmonary artery pressure (Ppa) and flow waves. The mean (+/- SE) Ppa was 63 +/- 3 mm Hg, and the mean PVR was 16 +/- 2 Wood units. The PVZ spectrum was markedly shifted to higher than normal pressures and frequencies, with a mean 0-Hz impedance (Z(0)) of 1,506 +/- 138 dyne. s. cm(-5), and a mean characteristic impedance (Zc) of 124 +/- 11 dyne. s. cm(-5), which are in keeping with data from previous studies. Inhaled NO levels decreased Ppa, PVR, Z(0), and Zc without a change in cardiac output. Epoprostenol administration did not affect Ppa, increased cardiac output, and decreased Z(0) and Zc. Dobutamine administration increased cardiac output and Ppa, and decreased PVR and Z(0), without changing Zc.

CONCLUSIONS

The determination of PVZ to quantify RV afterload is feasible during routine right heart catheterization and Doppler echocardiography. The measurement is sensitive to pharmacologic interventions.

Effects of epoprostenol on right ventricular hypertrophy and dilatation in pulmonary hypertension

OBJECTIVES

To gain more knowledge of changes in main pulmonary artery flow and right ventricular mass and volumes in patients with pulmonary hypertension during epoprostenol therapy.

METHODS

Eleven patients (9 women) were evaluated before the start of therapy and every 4 months thereafter. Right and left ventricular volumes and masses were measured by cine MRI. Flow was measured with MRI velocity quantification. At the same times, 6-min walking tests were performed. Right-heart catheterizations were performed at baseline and after 1 year.

RESULTS

Right ventricular mass in the patient group was significantly higher from that in a control group of healthy volunteers (95 +/- 26 g vs 42 +/- 10 g, p < 0.05 [mean +/- SD]), whereas the stroke volume was lower (34 +/- 11 mL vs 81 +/- 11 mL, p < 0.05). The greatest improvement in right ventricular stroke volume (to 41 +/- 11 mL, p < 0.05) took place in the first 4 months. During the 1-year follow-up, right ventricular end-diastolic volume and mass did not change, and mean pulmonary artery pressure remained nearly stable at 55 mm Hg at baseline and 53 mm Hg after 1 year. Pulmonary vascular resistance decreased by 12.5% (p = 0.06).

CONCLUSIONS

From these data we conclude that epoprostenol lowers pulmonary vascular resistance, leading to an increase in pulmonary artery flow. This increase in pulmonary artery flow corresponds well with the increase in 6-min walking distance and can be noninvasively monitored by MRI (flow quantification). Right ventricular dilatation and hypertrophy are not reversed by epoprostenol therapy, but do not progress either.

Low fractional diastolic pressure in the ascending aorta increased the risk of coronary heart disease

Although the fractional pulse pressure in the ascending aorta is related to the occurrence of coronary heart disease (CHD) and restenosis after percutaneous transluminal coronary angioplasty, the relative values of diastolic pressure in the ascending aorta at the onset of CHD have not been reported. The purpose of this study was to evaluate whether the relative values of diastolic pressure are associated with the risk of CHD. For this study, we enrolled 406 patients with chest pain, normal contractions, no local asynergy, and no history of myocardial infarction. We measured the ascending aortic pressure using a fluid-filled system. To quantify the relative diastolic pressure, we normalised the diastolic pressures to the mean pressure and referred to this value as the fractional diastolic pressure (FDP). We investigated the association between the FDP and the risk of CHD. Low FDP in the ascending aorta was associated with an increased risk of CHD. The multiple-adjusted odds ratio of CHD was 1.68 (95% CI, 0.67-4.22) in FDP for the middle tertile of the level. The multiple-adjusted odds ratio of CHD was 2.20 (1.16-4.75) in FDP for the lowest tertile compared with the highest tertile. FDP was associated with the risk of CHD.

Usefulness and limits of transthoracic echocardiography in the evaluation of patients with primary and chronic thromboembolic pulmonary hypertension

The aim of the study was to evaluate the potential usefulness of transthoracic echocardiography in differentiating patients with primary or chronic thromboembolic pulmonary hypertension and to define the capability of echocardiography to assess right-heart performance in such patients. Right-heart catheterization and ultrasound examination were performed in 111 patients with chronic thromboembolic pulmonary hypertension and in 31 patients with primary pulmonary hypertension. All echocardiographic and Doppler parameters were similar in primary and chronic thromboembolic pulmonary hypertension. A significant correlation was found between the tricuspid annular plane systolic excursion and the right ventricular fractional area change and thermodilution-derived right ventricular ejection fraction (P <.001 for both). Furthermore, different patterns of the pulsed Doppler flow velocity curve into the superior vena cava were associated with different right-heart hemodynamic profiles. In conclusion, in patients with chronic pulmonary hypertension transthoracic echocardiography portends meaningful information on the capability of the right heart to confront the increased afterload but it does not permit etiologic differentiation.

Ascending fractional pulse pressure closely relating to large artery function

It is not known whether ascending fractional pulse pressure (PPf) is related to large artery function. This study was to evaluate whether PPf is associated with large artery function by augmentation index. A total of 190 subjects were enrolled (age range: 50 to 78 years) who had normal contractions, no local asynergy, and no history of myocardial infarction. The ascending aortic pressure was measured using a fluid-filled system. To quantify the relative magnitude of the pulsatile to mean artery pressure, we normalised the pulse pressure to the mean pressure and referred to this value as PPf and the association between the PPf and the augmentation index was investigated. Augmentation index showed significant associations with PPf by univariate analysis (R = 0.690, P < 0.001). The associations between PPf and the factors influencing large artery function were examined by multivariate analysis, and PPf revealed significant associations with age, mean aortic pressure, heart rate and type 2 diabetes (R(2) = 0.477, P < 0.001). The results were that ascending aortic PPf is closely associated with large artery function detected by augmentation index.

Incidence and clinical characteristics of chronic pulmonary thromboembolism in Japan compared with acute pulmonary thromboembolism: results of a multicenter registry of the Japanese Society of Pulmonary Embolism Research

The incidence of acute pulmonary thromboembolism (APTE) in Japan is quoted as being extremely low compared with the United States, and the incidence and clinical characteristics of chronic pulmonary thromboembolism (CPTE) in Japan is unknown, so this study investigated these aspects of CPTE in 309 patients with APTE and 68 patients with CPTE. The ratio of the incidence of CPTE to APTE was 0.22 and there was no significant difference in age or sex between the APTE and CPTE patients. All of the predisposing factors for pulmonary thromboembolism, except for thrombophilia, were more frequently seen in the patients with APTE. There are some differences in the incidence and clinical characteristics of CPTE compared with APTE between Japanese and American patients in Japan, suggesting that the pathogenesis of CPTE in Japan may differ from that in the USA.

Lessons to be learned: a case study approach a case study of the temporal onset of pulmonary hypertension with pre-existent cirrhotic portal hypertension

We report the occurrence of pulmonary hypertension in a 37-year-old male patient with cirrhosis of the liver, portal hypertension and oesophageal varices. Although this is a rare combination, previous reports have shown that the association of portal and pulmonary hypertension is not coincidental; the temporal onset of primary pulmonary hypertension is hard to predict and our patient was asymptomatic for a number of years. The pathogenesis of portal hypertension leading to pulmonary hypertension is not known. Diagnosis is difficult because the clinico-pathological symptoms in both conditions are similar. Treatment is limited to calcium channel blockers, vasodilators, nitrous oxide and prostacyclin, although most patients will eventually require visceral transplantation.

Pulmonary artery reflection for differentially diagnosing primary pulmonary hypertension and chronic pulmonary thromboembolism

OBJECTIVES

The purpose of this investigation was to differentiate chronic pulmonary thromboembolism (CPTE) from primary pulmonary hypertension (PPH) by means of the indexes of pulmonary arterial reflection.

BACKGROUND

These differences in the primary lesions would make pulmonary artery reflection occur earlier in CPTE than in PPH. Although the analysis of pulsatility of pulmonary arterial pressure is useful in the differential diagnosis of PPH and CPTE, it is not known whether the analysis of pulmonary artery reflection can differentiate CPTE from PPH.

METHODS

Since CPTE predominantly involves the proximal arteries, whereas PPH involve the peripheral arteries, we hypothesized that patients with CPTE have a large augmentation index and a short inflection time. For this study, we enrolled 62 patients who had CPTE (31 patients) and PPH (31 patients). We measured pulmonary arterial pressure using a fluid filled system that included a balloon-tipped flow directed catheter. To quantify the pulmonary artery reflection, we used the augmentation index and inflection time.

RESULTS

The augmentation index was markedly higher in CPTE than it was in PPH (27.4% +/- 15.2% [SD] and -25.1% +/- 26.9%, respectively, p < 0.001) and was diagnostic in separating the two groups. Inflection time separated the two groups reasonably well (97 +/- 20 ms and 210 +/- 49 ms, respectively, p < 0.001).

CONCLUSIONS

The analysis of pulmonary arterial reflection is useful in the differential diagnosis of CPTE and PPH.