A comparison of noninvasive MRI-based methods of estimating pulmonary artery pressure in pulmonary hypertension

PURPOSE: To assess the accuracy of several noninvasive MRI-based estimators of pulmonary artery pressure by comparing them with invasive pressure measurement. MATERIALS AND METHODS: We compared five MRI methods with invasive pressure measurement by catheterization, in one group of pulmonary hypertension (PH) patients. Doppler echocardiography was included as a reference method. Main inclusion criterion was a mean pulmonary artery pressure above 25 mmHg at catheterization. MRI velocity quantification was used to obtain pulmonary flow acceleration and ejection times, and pulse wave velocity. The ventricular mass index was also assessed on MRI. Two commercially available 1.5-T systems were used for this study. RESULTS: Data from 44 patients were analyzed. Correlation of acceleration time with mean pressure was: r = -0.21, P = 0.21, correlation of the acceleration/ejection time ratio with systolic pressure was: r = -0.26, P = 0.01. The ventricular mass index showed the best correlation with mean pressure, with r = 0.56, P < 0.001. Using the pulse wave velocity and the cross-sectional area of the pulmonary artery, the mean pressure could not be estimated accurately. CONCLUSION: Accurate estimation of pulmonary artery pressure in PH patients was not feasible by the MRI estimators studied. These noninvasive methods cannot replace right heart catheterization at this moment.     

超声心动图在肺动脉分支狭窄支架植入术中的应用

目的:评价超声心动图在肺血管分支狭窄支架植入术中的应用价值。方法:回顾性分析13例肺血管分支狭窄支架植入患者术前、术中及术后随访的的超声心动图诊断资料。结果:13例患者术前超声诊断均正确,术前超声测量狭窄段血管内径为(0.49±0.19)cm,心血管造影测量狭窄段内径为(0.54±0.25)cm,二者间高度相关(P<0.01,r=0.94);术前超声估测跨狭窄段压差为(62.25±26.41)mmHg,心导管所测压差为(45.73±32.03)mmHg,二者间高度相关(P<0.05,r=0.88)。13例患者共植入16根血管支架,术后即刻超声估测压差为(22.44±14.49)mmHg,较术前明显下降(P<0.01)。术后1个月随访,14根支架效果良好,2根支架发生异位,滑脱入右心室。结论:超声心动图在肺动脉分支狭窄的术前诊断、支架植入术中监测、术后即刻效果判断及随访中起重要作用,是一种有效的监测手段。     

Arterial switch procedure for D-transposition of the great arteries: quantitative midterm evaluation of hemodynamic changes with cine MR imaging and phase-shift velocity mapping-initial experience

PURPOSE: To evaluate cine magnetic resonance (MR) imaging and phase-shift velocity mapping for assessment of the hemodynamic relevance of stenotic segments or specific hemodynamic changes in the great vessels after an arterial switch procedure for correction of D-transposition of the great arteries. MATERIALS AND METHODS: Twenty consecutive patients (age range, 2-17 years) with an acoustic window that was insufficient for Doppler transthoracic echocardiography were included in the study. Flow and diameter measurements of the pulmonary arterial trunk and its primary branches were performed with phase-shift velocity mapping and cine MR imaging. RESULTS: There were good correlations between pressure gradients in the pulmonary arteries estimated with MR imaging and those measured with Doppler echocardiography (r = 0.83, n = 15) and cardiac catheterization (r = 0.90, n = 13). Cine MR imaging revealed that the diameters of the right and left pulmonary arteries decreased with the expansion of the aorta during systole, which increased the peak velocity. This temporary stenosis was more severe in the right than in the left pulmonary artery and was accompanied by a significantly (P <.05) lower volume flow in the right artery. CONCLUSION: The anatomic situation after arterial switch repair tended to produce temporary stenoses in the primary pulmonary arterial branches, with significant changes in hemodynamics. These changes may affect the long-term outcome and go undetected with other imaging modalities.     

彩色多普勒超声心动图在老年动脉导管未闭封堵术中的价值

目的探讨彩色多普勒超声心动图(CDE)在老年动脉导管未闭(PDA)封堵术中的价值。方法封堵术前应用CDE筛选25例老年PDA适应证,彩色多普勒血流显像(CDFI)分流束血流信号估测PDA肺动脉端直径,与心血管造影对照,经统计学相关处理判断其正确性;连续波多普勒(CW)测量三尖瓣最大反流速度峰值,根据简化伯努利方程ΔP=4V2估算跨三尖瓣压力阶差,再加上右心房固有压力估测肺动脉压力,与心导管对照,经统计学相关处理判断其正确性;所有患者均行封堵术介入治疗,封堵术后再应用CDE判断封堵术疗效。结果根据CDE特征筛选25例老年PDA实施封堵术全部获得成功,封堵术后CDE判断疗效满意。CDFI测量分流束血流信号估测PDA肺动脉端直径与心血管造影对照,呈正相关(r=0.71,P<0.001);CW估测肺动脉压力与心导管对照,呈正相关(r=0.63,P<0.001)。结论CDE在老年PDA封堵术中具有重要价值,封堵术前筛选适应证应用CDFI估测PDA肺动脉端直径和应用CW估测肺动脉压力是关键,封堵术后判断疗效应用CDFI观察有无过PDA残余分流很重要。     

Renal uptake on lung perfusion scintigraphy in a patient with primary pulmonary hypertension

An 18-year-old woman presented with primary pulmonary hypertension (PPH) and was hospitalized because of hemoptysis and was referred to our department for a differential diagnosis pulmonary thromboembolism. Doppler ultrasonography of the lower extremities was normal. Echocardiography and cardiac catheterization showed right ventricular dilatation and increased pulmonary artery pressure without anatomic (intracardiac) shunt. The mean pulmonary arterial pressure was 110 mm Hg. Tc-99m MAA lung perfusion scans showed nonsegmental patchy defects. Extrapulmonary renal uptake and increased systemic deposition of radiotracer were seen in the MAA scintigraphy. It could be related to a functional intrapulmonary shunt resulting in increasing pressure in the pulmonary artery in PPH.     

Simultaneous assessment of right ventricular function and hypertrophy by Tc-99m MIBI

PURPOSE: Tc-99m MIBI allows the simultaneous performance of cardiac blood pool scintigraphy and myocardial SPECT. The authors performed studies to determine whether right ventricular function and hypertrophy can be evaluated simultaneously using Tc-99m MIBI in patients with right heart disease. METHODS: Using right heart catheterization, several parameters of pulmonary circulation were measured, including right ventricular ejection fraction, in 23 patients with chronic pulmonary disease and pulmonary vascular disease. Within 1 week, right heart blood pool scintigraphy was performed using the first-pass method using Tc-99m MIBI. The right ventricular ejection fraction calculated from right heart blood pool scintigraphy was compared with that measured using right heart catheterization. Myocardial SPECT was performed 1 hour after right heart blood pool scintigraphy. On the short axis images, which allowed optimal visualization of the right ventricle, the right and left ventricular free walls were established as regions of interest. Myocardial wall counts were determined. The right ventricular uptake: left ventricular uptake ratio was calculated to study the relation of that ratio to mean pulmonary artery pressure and total pulmonary resistance. RESULTS: A significant correlation was observed between the right ventricular ejection fraction calculated on right heart catheterization and that calculated on right heart blood pool scintigraphy. The right ventricular uptake:left ventricular uptake ratio correlated positively with pulmonary artery pressure and total pulmonary resistance. CONCLUSION: These results suggest that Tc-99m MIBI allows simultaneous noninvasive evaluation of cardiac function and structure, which previously was considered impossible in patients with right heart disease.     

The assessment of pulmonary arterial pressure by pulsed Doppler in patients with obstructive pneumopathy]

The severity of pulmonary arterial hypertension can be assessed by duplex-Doppler echocardiography, a subxiphoid approach and a general-purpose duplex device. Normally, the peak Doppler flow velocity occurs in midsystole and the flow profile is parabolic (bullet-like). In pulmonary arterial hypertension, changes in vascular compliance cause maximal acceleration of blood in early systole, with shortening of pulmonary acceleration time (AcT, or time to peak velocity). In the more severe cases, a midsystolic notching is visible, related to rapid deceleration of blood flow, followed by a brief secondary increase in velocity in the late systole. We studied 19 adult patients with chronic obstructive pulmonary disease with duplex-Doppler examination, with a subxiphoid approach and right heart catheterization. The study was diagnostic in all cases with Doppler recordings of good quality. An relationship was found between AcT and pulmonary mean or systolic arterial pressure at rest. An evident accurate prediction of pulmonary arterial pressure in emphysematous patients is possible by means of pulsed Doppler, also in case of low-level hypertension. We believe this method to be a simple and reliable adjunct to the non-invasive work-up of emphysematous patients and to represent a good alternative to the classical parasternal approach, which is often not feasible in these patients.     

连续波多普勒超声和双心导管同步测量二尖瓣返流压差的研究

目的：为了探讨连续波多普勒超声技术测量二尖瓣返流压差的难确性。材料和方法：在25例二尖瓣返流患者利用连续波多普勒超声和左、右心导管技术同步测量了静思和负荷状态下30例次的二尖瓣返流压差。结果：多普勒超声测量的最大返流压差与心导管测量的最大返流压差和峰间压差高度相关（r＝0．99和0．92）。结论：连续波多普勒超声是估测二尖辩返流压差无创性可靠技术。     

Non-invasive assessment of congenital pulmonary vein stenosis in children using cardiac-non-gated CT with 64-slice technology

Background

Management of congenital pulmonary vein stenosis is a diagnostic challenge. Echocardiography may be insufficient and thus cardiac catheterization remains the reference standard in this setting. The aim of the study was to investigate the accuracy of cardiac-non-gated CT using 64-slice technology in detecting congenital pulmonary vein stenosis in children.

Materials and methods

CT examinations were consecutively performed from May 2005 to December 2006 in 13 children aged 1.5–12 months (median 5 months) for suspected congenital pulmonary vein stenosis. Cardiac-non-gated CT acquisitions were performed after the peripheral injection of contrast agent. Pulmonary veins were evaluated for their pattern of connectivity from the lung to the left atrium and for the presence of stenosis. CT findings of pulmonary vein stenosis were compared with combined findings available from echocardiography, catheterization and surgery.

Results

Pulmonary veins from the right lung (n = 29) and left lung (n = 26) were evaluated as separate structures (N = 55). Of the 55 structures, 32 had surgical and/or catheterization data and 45 had echocardiography for comparison. CT visualized 100% (55/55) of the investigated structures, while echocardiography visualized 82% (45/55). In the 13 subjects CT identified 10 stenotic pulmonary veins. CT confirmed the echocardiography suspicion of pulmonary vein stenosis in 100% (7/7) and established a new diagnosis in 3 other patients. CT agreed with surgery/catheterization in 100% (10/10) of the available comparisons.

Conclusion

Cardiac-non-gated CT assessed the pulmonary veins more completely than echocardiography and should be considered as a viable alternative for invasive pulmonary venography for detecting pulmonary vein stenosis in children.