Three-Dimensional Color Doppler Transesophageal Echocardiography for Mitral Paravalvular Leak Quantification and Evaluation of Percutaneous Closure Success




Background


Three-dimensional (3D) color Doppler transesophageal echocardiography (TEE) enables accurate planimetry of the effective regurgitant orifice (ERO) of a mitral paravalvular leak (PVL). The aim of this study was to evaluate the usefulness of this method to quantify paravalvular regurgitation and to assess percutaneous PVL closure success, compared with 3D planimetry of PVLs without using color-flow images (3D anatomic regurgitant orifice [ARO]).


Methods


Forty-six patients (59 mitral PVLs) who underwent 3D TEE to evaluate the indication of PVL closure procedure were retrospectively included. Receiver operating characteristic curves were compared to identify degree III and IV paravalvular regurgitation of 3D color ERO and 3D ARO measures. Forty patients underwent percutaneous PVL closure procedures; analysis was conducted to determine whether the undersizing of the closure devices according to 3D color ERO and 3D ARO measures was associated with PVL closure failure.


Results


Three-dimensional ERO measures showed better areas under the curve than 3D ARO measures and correlated better with the degree of paravalvular regurgitation. Three-dimensional color ERO major diameter ≥ 0.65 cm showed a positive predictive value of 87.1% and a negative predictive value of 94% to diagnose degree III and IV paravalvular regurgitation. For the 40 patients who underwent PVL closure procedures, the immediate technical success rate was 76.9%, and 1-year estimated survival was 69.5%. Closure device undersizing according to 3D color ERO length, but not other PVL measurements, was significantly associated with PVL closure failure ( P = .007).


Conclusion


Three-dimensional ERO was superior to 3D ARO at identifying the presence of degree III and IV paravalvular regurgitation. The undersizing of closure devices according to 3D color ERO length was associated with failed closure procedures. Confirmatory prospective studies are encouraged.


Paravalvular leaks (PVLs) are a common complication after mitral valve replacement surgery. Three-dimensional (3D) transesophageal echocardiography (TEE) has emerged as the preferred imaging modality to evaluate the morphology and extent of these leaks, as it better demonstrates, compared with two-dimensional (2D) echocardiography, the shapes and sizes of the leaks. Three-dimensional TEE is also the recommended technique to guide transcatheter PVL closure procedures.


However, severity assessment of paravalvular regurgitation caused by PVL using 3D TEE is technically difficult. Common measurements of mitral regurgitation severity, such as jet width (vena contracta) and jet area on color-flow imaging, are useful in this context, but other parameters, such the proximal isovelocity surface area radius, have not been validated.


PVL sizing can be performed by 3D transesophageal echocardiographic planimetry without using color-flow images, by measuring the areas of echo dropout that represent the presence of a leak. This method actually measures the anatomic regurgitant orifice (ARO) size rather than the effective regurgitant orifice (ERO). Moreover, it may overestimate or underestimate the sizes of PVLs, as the extension of these anechoic areas depends on parameters such as the gain and compression values used for the acquisition of images, and resolution may be limited.


Three-dimensional transesophageal echocardiographic planimetry using color-flow images may improve PVL sizing, as it enables accurate planimetry of the ERO of the leaks. Our aim was to evaluate the usefulness of this method to quantify paravalvular regurgitation and its capacity to assess percutaneous PVL closure success. We also analyzed the differences between PVL dimensions calculated with the 3D color ERO and 3D ARO approaches, to detect if either of the two methods was associated with systematic over- or underestimation.


Methods


Study Population


We retrospectively included every consecutive patient with a diagnosis of mitral PVL who underwent 3D TEE at our center to consider the indication of a PVL closure procedure between January 2009 and July 2011. No method for sample size calculation was used. Instead, we studied every available subject. All information was recorded in a dedicated database, and all echocardiographic images were stored in Digital Imaging and Communications in Medicine 3.0 and row data in a digital system. Of the 53 patients initially included, seven lacked the 3D transesophageal echocardiographic color-flow images necessary for the quantification of 3D color ERO and were excluded from the analysis. Hence, a total of 46 patients, with a total of 59 mitral PVLs, were included in the analysis. Of these 46 patients, 40 (52 leaks) underwent percutaneous transcatheter PVL closure procedures. All procedures were performed with 3D transesophageal echocardiographic guidance, and the devices used in all cases were Amplatzer Vascular Plug III occluders (St Jude Medical, Plymouth, MN). At our institution, these procedures are performed in all cases using both retrograde aortic and antegrade transseptal approaches, with the creation of an arteriovenous rail through the leak to snare and exteriorize the wire, so that more support for sheath and device delivery is achieved. In 31 patients, the retrograde aortic approach was first performed to cross the leak with the wire. In the remaining nine patients, the antegrade transseptal approach was first selected to cross the leak; in one of these patients, transseptal puncture was not possible, so only the retrograde aortic approach without the use of an arteriovenous rail was used.


The size selection of the device was carried out intraprocedurally using a sizing approach that measured the 3D dimensions of the leak without using color imaging and without image postprocessing. Color-flow images were also used, but because no postprocessing was carried out, the 3D color ERO measures (or the 3D ARO measures) were not calculated then. The operator then selected, among the available device sizes, the one or ones that best fit the size of the defect. Twenty-eight patients (34 leaks) underwent postoperative follow-up 3D TEE at our center and were included in the analysis of PVL closure success. The study complied with the Declaration of Helsinki.


Demographic and Clinical Variables


Demographic and clinical data from patients were retrospectively collected from their medical records. In patients who underwent PVL closure, we identified three possible indications for the procedure: heart failure, symptomatic hemolytic anemia, or a combination of the two.


Echocardiographic Technique and Measurements


Conventional 2D transthoracic echocardiographic studies were performed before TEE in all patients, to measure atrial and ventricular dimensions and left ventricular ejection fraction. All transesophageal echocardiographic studies were conducted with a Philips iE33 ultrasound system and an X7-2t transesophageal transducer (Philips Medical Systems, Andover, MA). A first approach with 2D TEE was used to locate the best planes. Afterward, a 3D subvolume that included the mitral valve and the left atrial walls was recorded. Additional 3D zoom loops focused on the locations of the PVLs were also acquired. Next, 3D color-flow loops focused on paravalvular regurgitation were recorded. All 3D transesophageal echocardiographic loops included at least three cardiac cycles.


Three-dimensional transesophageal echocardiographic loops were processed using QLAB (Philips Medical Systems). The number of PVLs, as well as their dimensions (length, width, and area), calculated by planimetry of the areas of echo absence (3D ARO), were recorded; to measure the dimensions of each PVL, a 2D plane was extracted from the 3D subvolume of interest using the QLAB multiplanar reconstruction tool ( Figure 1 ). To calculate the 3D color ERO, the 3D transesophageal echocardiographic color-flow loops were processed using the multiplanar reconstruction tool of QLAB (similarly to the analysis of 3D subvolumes), to select the 2D plane that represented the ERO. Monochromatic color-flow mode was selected to facilitate the measurements. Once the best 2D plane was selected, planimetry of the colored area was performed to calculate the length, width, and area of the 3D color ERO ( Figure 2 ). The procedure was feasible for 58 of the 59 PVLs. We also calculated the eccentricity index, defined as the ratio between the length and width of the PVL, using both 3D ARO and 3D color ERO measurements.




Figure 1


Three-dimensional ARO quantification. Three-dimensional transesophageal echocardiographic loops are recorded for this purpose. A midsystolic frame is selected for quantification (A) ; the position of the leak that will be measured is highlighted ( arrow ). Using the multiplanar reconstruction tool in QLAB (Philips Medical Systems), the 2D plane that includes the anatomic orifice of the leak is extracted (B) . Finally, the length, width, and area of this anatomic orifice (3D ARO) are measured using planimetry (C) .



Figure 2


Three-dimensional color ERO quantification of the same leak as in Figure 1 . Three-dimensional transesophageal echocardiographic color-flow loops are recorded for this purpose (A) ; this patient had two leaks ( asterisks ), and the one being measured is highlighted ( arrow ). Using QLAB (Philips Medical Systems) with a monochromatic color-flow mode, the loops are played, and the frame in which the origin of the regurgitant jet is best visualized is selected. Then, the multiplanar reconstruction tool allows the selection of the 2D plane that best shows the regurgitant orifice (B) . Finally, the length, width, and area of the colored surface of the selected 2D plane, which represents the 3D color ERO, are measured using planimetry (C) . In this case, the 3D color ERO measures were slightly higher than the 3D ARO measures.


The location of each PVL was defined with respect to the aortic valve, using a clocklike approach similar to that used in heart surgery, with the aortic valve represented as 12 o’clock, the left atrial appendage represented as 9 o’clock, the posterior mitral annulus represented as 6 o’clock, and the interatrial septum represented as 3 o’clock ( Figure 3 ). Anterior location was defined for PVLs situated between 12 and 3 o’clock, septal location for PVLs between 3 and 6 o’clock, posterior location for PVLs between 6 and 9 o’clock, and lateral location for PVLs between 9 and 12 o’clock.




Figure 3


PVL locations. AO , Aortic valve; IAS , interatrial septum; LAA , left atrial appendage.


The paravalvular regurgitation severity of each PVL was established as mild (degree I), mild to moderate (degree II), moderate (degree III), or severe (degree IV), according to the recommendations for native valve regurgitation. To set the degree of paravalvular regurgitation of each PVL, the mean degree of severity using several parameters was calculated ( Table 1 ): the jet width, length, and area on color-flow images; the relationship between the regurgitant jet area and the left atrial area; and the pulmonary vein pulsed-wave Doppler pattern. The grading was performed by an expert echocardiographer, who also conducted the intraprocedural transesophageal echocardiographic studies used to guide the PVL closure procedures. To guarantee independent grading of paravalvular regurgitation, the echocardiographer was unaware of PVL dimensions by 3D ARO and 3D color ERO approaches.



Table 1

Grading of paravalvular regurgitation












































Mild PVR Moderate PVR Severe PVR
Color Doppler imaging
Jet width (vena contracta) (cm) <0.3 0.3–0.69 ≥0.7
Jet length Short central jet Central jet: reaches the top of the atrium or penetrates into the pulmonary veins; eccentric jet: swirling in the left atrium
Jet area (cm 2 ) <4 4–9.9 ≥10
Jet area/left atrial area (%) <10 10–19.9 ≥20
Pulsed Doppler
Pulmonary vein flow Dominant systolic wave Dominant diastolic wave Systolic wave reversal

PVR , Paravalvular regurgitation.

When there were parameters consistent with both mild and moderate PVR, degree II (mild to moderate) was used, unless the vast majority of criteria indicated moderate regurgitation (degree III was then used). When there were parameters consistent with both moderate and severe PVR, the degree used was the one with more parameters indicating it, unless the vena contracta clearly indicated severe mitral regurgitation (degree IV was then used).

Because the vast majority of mitral prostheses have dilated left atria, we chose jet areas < 10% of left atrial area as a marker of mild regurgitation (instead of <20%) and jet areas ≥ 20% of left atrial area as a marker of severe regurgitation (instead of ≥40%).



Analysis of PVL Closure Success Rates


The analysis of closure success was performed for the 28 patients (34 leaks) who underwent postprocedural follow-up 3D TEE sat our center. Technical success of the procedure was defined as the correct deployment of the device or devices, a reduction in the previous degree of paravalvular regurgitation, the lack of significant residual regurgitation (degrees III and IV), and the absence of new prosthetic valve malfunction.


To determine if PVL size influenced the probability of technical success of the closure procedure, we compared the PVL measures (calculated with the 3D color ERO approach and with 3D ARO) of the successfully closed PVLs and those of the unsuccessfully closed PVLs. Moreover, we compared the rates of technical success for PVLs in different locations. We also explored if the choice of an undersized device could result in a failed closure procedure. To do so, we compared the rates of technical success for undersized devices (defined as those devices with length, width, or area shorter than the PVL dimensions, calculated with the 3D color ERO method and with 3D ARO) to the rates obtained with well-sized devices (those with greater or equal dimensions than the PVL).


For the entire cohort of 40 patients who underwent percutaneous PVL closure, we calculated the mortality rate at last follow-up and the survival estimates with 95% confidence intervals (CIs) at 6 months and 1 year, using the Kaplan-Meier method. We also collected functional New York Heart Association functional class, plasma hemoglobin level, and the number of patients who subjectively reported clinical improvement.


Statistical Analysis


Categorical variables are described as number (percentage) and were compared by using χ 2 or the Fisher’s exact tests, as appropriate. Continuous variables are described as mean ± SD for variables with normal distributions or as median (interquartile range) for variables not normally distributed. The Kolmogorov-Smirnov test was used to assess normality in continuous variables. Comparisons among normal continuous variables were made using Student’s t tests (two-group comparisons) or analysis of variance (for comparisons among more than two groups); for variables not normally distributed, Mann-Whitney U tests (two-group comparisons) and Kruskal-Wallis tests (for comparisons among more than two groups) were used. Bilateral P values < .05 were considered statistically significant.


We performed a reliability analysis of the 3D color ERO measures, in comparison with 3D ARO measures. To do so, the intraclass correlation coefficients for PVL dimensions using both methods were calculated, and the presence of systematic over- or underestimation of PVL dimensions by any of the two methods was evaluated using Student’s paired t test. For the validation analysis of 3D color ERO to assess the severity of paravalvular regurgitation, receiver operating characteristic (ROC) curves were calculated for each evaluated echocardiographic parameter to correctly diagnose the presence of moderate or severe (degrees III and IV) paravalvular regurgitation. Optimal cutoff values for each parameter were defined as those with the shorter distance to the top left corner of the ROC graph. To compare the capacity of the evaluated echocardiographic parameters to determine the severity of paravalvular regurgitation, Spearman correlation coefficients (ρ) between the degree (I–IV) of paravalvular regurgitation and each echocardiographic variable were calculated.


Statistical analysis was performed using SPSS PASW Statistics version 15.0 package (SPSS, Inc, Chicago, IL). The comparison of the areas under the curve of ROC curves was performed using MedCalc version 13.3.3 (MedCalc Software, Mariakerke, Belgium).




Results


A total of 46 patients (59 mitral PVLs) were studied. Demographic and clinical characteristics of these patients are shown in Table 2 . The mean time from the last mitral valve replacement surgery to mitral PVL diagnosis was 10.9 ± 8.7 years. Echocardiographic measurements and mitral PVLs characteristics at diagnosis are shown in Table 3 . Three-dimensional color ERO measurements could be performed in 58 PVLs. Of these PVLs, three (5.1%) caused degree I paravalvular regurgitation, 25 (43.1%) caused degree II paravalvular regurgitation, 15 (25.9%) caused degree III paravalvular regurgitation, and 15 (25.9%) caused degree IV paravalvular regurgitation.



Table 2

Patients’ demographic and clinical characteristics
































































Variable Value
Demographic characteristics
Age at PVL diagnosis (y) 64.8 ± 10.6
Men 19 (41.3%)
Medical history
Arterial hypertension 16 (34.8%)
Diabetes mellitus 9 (19.6%)
Hypercholesterolemia 17 (37.0%)
Smokers 8 (17.4%)
Current smokers 3 (6.5%)
Former 5 (10.9%)
Chronic renal failure (%) 8 (17.4%)
Atrial fibrillation 29 (63.0%)
Ischemic cardiomyopathy 5 (10.9%)
Mitral valve disease history
Age at first mitral valve replacement surgery (y) 47.6 ± 16.4
Number of reoperated patients 22 (47.8%)
Age at current mitral valve replacement surgery (y) 53.2 ± 13.2
Number of mechanical prosthesis 43 (93.5%)
Prosthesis size (mm) 27 ± 1.96

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

May 31, 2018 | Posted by in CARDIOLOGY | Comments Off on Three-Dimensional Color Doppler Transesophageal Echocardiography for Mitral Paravalvular Leak Quantification and Evaluation of Percutaneous Closure Success

Full access? Get Clinical Tree

Get Clinical Tree app for offline access