Right Ventricle, Right Atrium, Tricuspid and Pulmonic Valves



Right Ventricle, Right Atrium, Tricuspid and Pulmonic Valves


André Y. Denault

Etienne J. Couture

Ying Tung Sia

Georges Desjardins



INTRODUCTION

Right ventricular (RV) dysfunction is a common concern in the perioperative period. Inadequate myocardial protection, increases in pulmonary vascular resistance, air embolism to the right coronary artery, volume overload, and acute valvular dysfunction can compromise RV performance. This chapter surveys the echocardiographic approaches for evaluating the right side of the heart including the tricuspid valve (TV) and pulmonic valve (PV).


RIGHT VENTRICLE


Anatomy

From a functional perspective the RV consists of inflow and outflow tracts separated by the trabeculated apical myocardium. However, the RV’s nongeometric, asymmetric shape complicates echocardiographic evaluation (Fig. 14.1). Morphologically, the RV is described in terms of three components: (1) the inlet, which consists of the TV, chordae tendineae, and papillary muscles; (2) the trabeculated apical myocardium; and (3) the infundibulum, or conus, which corresponds to the smooth myocardial outflow region (Fig. 14.1). RV regional function is further categorized as anterior, lateral, and inferior walls, infundibulum, as well as basal, mid, and apical sections. Three prominent muscular bands divide the RV: the parietal, the septal, and the moderator band (Fig. 14.2). Its most apical portion with the distinctive moderator band is often well visualized with transesophageal echocardiography (TEE). The moderator band is a muscular trabeculation containing the right bundle branch, extending from the lower interventricular septum to the anterior papillary muscle of the RV lateral wall and serves as an anchoring structure for the tricuspid papillary muscles.


Transesophageal Echocardiographic Views (Fig. 14.3)



  • Mid-esophageal (ME) four-chamber view. This long-axis view of the RV allows assessment of all three segments, from apex to base, of the RV lateral wall. In this view, the RV appears triangular or horn shaped in comparison with the elliptic left ventricle (LV), and its length is only two-thirds the length of the LV. This view is recommended for rapid assessment of RV systolic and diastolic function (Fig. 14.3 #5).






    FIGURE 14.1 Right ventricular septal regions. MPA, mean pulmonary artery. (With permission of CAE Healthcare, Montreal, Canada.)







    FIGURE 14.2 Schematic drawing of anatomical structures in the right ventricle.


  • ME RV inflow-outflow view. Often termed the wraparound view as the right atrium (RA), RV, and pulmonary artery (PA) appear to “wraparound” the aortic valve (AoV) and left atrium, describing a 270° arc from left to right of the TEE monitor display. This view is favored for diagnosis of RV outflow tract obstruction (RVOTO) and assessment of infundibular (and anterior) wall function (Fig. 14.3 #6).


  • Transgastric (TG) basal and midpapillary short-axis view. The anterior, lateral, and inferior RV walls and the interventricular septum are evaluated from these views (Figs. 14.3 #10 to #12). These views are particularly useful in evaluation of the interventricular septum in order to determine the presence of RV volume or pressure overload (see below).


  • TG RV inflow view. Analogous to the two-chamber view of the LV, this view is acquired by advancing the multiplane angle 90° from the TG short-axis view of the RV or until the RA and RV are seen in long axis, with the RV inflow and TV centered in the image. Alternatively, one develops the TG two-chamber view of the left atrium and LV and then turns the probe clockwise (rightward) until the two right-sided chambers are displayed. Both techniques should result in similar images of the RV inflow tract and the long axis of the RA and the RV with the anterior and inferior RV wall (Fig. 14.3 #13). This view can be useful in evaluating basal RV function.


  • Deep TG RV outflow and inflow/outflow view. Due to the angulation of the ultrasound beam, this view is optimal to interrogate the tricuspid annulus with pulsed wave Doppler (PWD) or tissue Doppler (Figs. 14.3 #14 and #15). This view can be useful for diagnosing tricuspid valvular pathology and measuring pressure gradients across the TV and PV. It can be used also to evaluate RV diastolic function through interrogation of the basal inferior segment using tissue Doppler.


Assessment of Right Ventricular Structure


Right Ventricular Wall Thickness

The normal thickness of the RV lateral wall measures less than 5 mm at end-diastole (1,2,3). RV hypertrophy is present when the RV lateral wall thickness exceeds 5 mm, indicating RV systolic pressure overload from elevated PA pressure, chronic pulmonary thromboembolism, RVOTO, or pulmonic stenosis (PS) (4). The inferior or lateral walls of the RV are the preferred locations for measurement since, in contrast to the anterior wall, they are not invested with as much epicardial fat that must be excluded from RV wall thickness measurement (5). The inferior wall of the RV is best assessed in TG views performed at 0°, whereas the RV lateral wall is best measured in the ME four-chamber view. Because the RV wall is thinner and more
trabeculated than the LV wall, precise measurements are more difficult to obtain. In patients with chronic cor pulmonale, the RV wall thickness may exceed 10 mm while intracavitary trabecular patterns become more prominent, particularly at the apex. Certain conditions are associated with RV wall thinning, such as RV myocardium infarction, Uhl syndrome, or arrhythmogenic RV cardiomyopathy. In the latter condition, the aneurysms occur most commonly in the anterior infundibulum, basal inferior wall, and apex. There are no accepted echocardiographic criteria to define an abnormally thin RV wall (3,6).






FIGURE 14.3 Transesophageal echocardiographic views to evaluate right-sided structures. Upper esophageal (UE), midesophageal (ME), transgastric (TG), and deep TG views are useful in the evaluation of right ventricular (RV) function. Asc, ascending; Ao, aorta; AoV, aortic valve; BA, basal anterior; BAS, basal anteroseptal; BI, basal inferior; BIS, basal inferoseptal; BL, basal lateral; CS, coronary sinus; DTG, deep transgastric; HV, hepatic vein; IVC, inferior vena cava; LA, left atrium; LAX, long axis; LBCV, left brachiocephalic vein; LE, low esophageal; LPA, left pulmonary artery; LV, left ventricle; MPA, main pulmonary artery; PA, pulmonary artery; PV, pulmonic valve; PVAC, pulmonic valve anterior cusp; PVLC, pulmonic valve left cusp; PVRC, pulmonic valve right cusp; RA, right atrium; RPA, right pulmonary artery; RV, right ventricle or ventricular; RVOT, right ventricular outflow tract; SAX, short axis; SVC, superior vena cava; TV, tricuspid valve; TVAL, tricuspid valve anterior leaflet; TVPL, tricuspid valve posterior leaflet; TVSL, tricuspid valve septal leaflet. (Reproduced and adapted from Denault AY, Couture P, Vegas A, et al. Transesophageal Echocardiography Multimedia Manual, Second Edition: A Perioperative Transdisciplinary Approach. New York: Informa Healthcare; 2011; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)



Right Ventricular Dimension

RV dimension is best estimated at end-diastole from an ME four-chamber view (Fig. 14.4). Care should be taken to obtain RV-focused image demonstrating its maximal diameter without foreshortening. This can be accomplished by making sure that the crux and apex of the heart are in view. Diameter >41 mm at the base and >35 mm at the midlevel indicates RV dilation. Similarly, longitudinal dimension, from the apex to tricuspid annulus, >86 mm indicates RV enlargement (2,3). RV dilation may be seen with RV volume or pressure overload. Normally, the RV end-diastolic cross-sectional area is approximately 60% of the area of the LV. As the RV dilates, its shape changes from triangular to round. In addition, the cardiac apex, which should be made up solely of the LV, may be equally shared between the ventricles or even dominated by the RV, indicating significant RV dilation. With mild RV dilation, the RV area is >70% of the LV area on two-dimensional (2D) imaging. With moderate RV dilation, the RV area may equal the LV area, and with severe RV enlargement, the RV area exceeds that of the LV (7).






FIGURE 14.4 Basic transesophageal echocardiography (TEE) measurements. A: TEE measurements, at end-diastole, of various right ventricular diameters (RVD) obtained from a mid-esophageal four-chamber view optimized to the maximum right ventricular (RV) size by varying angles 0° to 20°. The table shows normal and abnormal values for RVD1 and RVD2. B: TEE measurements, during end-diastole, of the right ventricular outflow tract (RVOT) at two levels (RVOT1, RVOT2) and the mean pulmonary artery (MPA) from the mid-esophageal right ventricular inflow/outflow view. C: TEE measurements, at ventricular end-systole, of the right atrium (RA) from the mid-esophageal four-chamber view optimally positioned to visualize both chambers. Table of normal and abnormal values for ventricular and atrial dimensions (mm ± standard deviation) and volumes (mL/m2) as absolute values and indexed to body surface area (BSA). AoV, aortic valve; LA, left atrium; LV, left ventricle; PV, pulmonic valve; TV, tricuspid valve. (Adapted from Lang RM, Badano LP, Mor-Avi V, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 2015;28[1]:1-39.e14; Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)



Interventricular Septum and Eccentricity Index

The analysis of interventricular septum may provide useful insights into RV pathology. Examination of interventricular septal motion can help distinguish RV volume overload from RV pressure overload. Normally, the interventricular septum functions as part of the LV and maintains a concave shape on the LV side throughout the cardiac cycle. As the RV dilates or becomes hypertrophic the septum flattens and paradoxical septal motion develops. Normally in systole, inward and outward motion of all the walls of the LV will be seen in systole and then in diastole. If there is an opposite motion of the interventricular wall during diastole, the term paradoxical motion is used. It can be seen in an ME four-chamber view or the TG midpapillary view. The eccentricity index, a measure of septal curvature, represents the ratio of the LV minor axis diameter (parallel to the septum) to its perpendicular axis. In normal subjects, the index is essentially one both at enddiastole and end-systole (Fig. 14.5 A,B). Acquired pressure overload situations such as pulmonary hypertension or pulmonary stenosis displace the interventricular septum toward the LV at end-diastole leading to a D-shaped LV with eccentricity index <1. The septal displacement reflects the pressure gradient between the two ventricles. In early stages of RV volume overload diastolic pressure in RV exceeds that in the LV thus pushing the septum toward LV cavity in diastole only (Fig. 14.5 C,D). With severe RV pressure overload, the LV exhibits a D shape in both diastole and systole (Fig. 14.5 E,F) (1,8).


Assessment of Right Ventricular Systolic Function

Quantitative assessment of RV systolic function can be done with volumetric and nonvolumetric assessments. However, its volumetric function evaluation is limited by its unique geometry, while variations in shape occur readily with changes in RV volume. RV ejection is a complex process involving three components—inward motion of the RV lateral wall, longitudinal shortening of the RV with systolic descent of the tricuspid annulus, along with contributions from the RVOT (1,4). Signs of RV dysfunction include severe hypokinesis or akinesis of the RV lateral wall, RV enlargement, change in shape of the RV from crescent to round, and flattening or bulging of the interventricular septum toward the left side.


Volumetric Function Assessment

Volumetric evaluation is commonly estimated by the right ventricular fractional area change (RVFAC) defined as (end-diastolic area – end-systolic area) / end-diastolic area × 100 assessed from the ME fourchamber view. Diagnosis of RV dysfunction is made by RVFAC <35% and its severity can be described as mild, moderate, or severe for values of 25% to 35%, 18% to 25%, and ≤18%, respectively (Fig. 14.6) (1). A limitation of this approach is that RVFAC does not examine contribution of the RV outflow tract that corresponds to approximately 20% of the ejected RV volume.


Nonvolumetric Function Assessment


Right Ventricular Myocardial Performance Index

Global assessment of RV function can be done by right ventricular myocardial performance index (RVMPI or Tei index) using PWD or tissue Doppler imaging (TDI) at the lateral tricuspid annulus. It represents an estimate of both RV systolic and diastolic function. It is based on the relationship between ejection and nonejection work of the heart. The RVMPI is defined as the ratio of isovolumetric time divided by ejection time (ET), or [(isovolumetric relaxation time (IVRT) + isovolumetric contraction time (IVCT))/(ET)]. Presence of RV dysfunction is characterized by an RVMPI >0.43 in PWD and >0.54 in TDI (2). The Tei index has been shown to be independent of the loading condition, of heart rate and atrioventricular valvular regurgitation (9). However, a major pitfall needs to be highlighted: a severe RV diastolic dysfunction can significantly reduce IVRT, thus preventing the increase of Tei index in the presence of severe systolic dysfunction. One should keep in mind that normal Tei index does not exclude both RV systolic or/and diastolic dysfunction. In valvular surgery, RVMPI is an independent predictor of difficult cardiopulmonary bypass (CPB) weaning, mortality, circulatory failure, duration of hospitalization and intensive care unit (ICU) stay (Fig. 14.7) (10).


Tricuspid Annular Plane Systolic Excursion

Long-axis systolic excursion of the lateral aspect of the tricuspid annulus represents an easy recognizable longitudinal movement on echocardiography and may be used as an indicator of RV systolic function. Typically measured in M-mode and corrected for angulation of interrogation, tricuspid annular plane systolic
excursion (TAPSE) is defined as the total excursion of the tricuspid annulus from end-diastole to end-systole. Normal TAPSE is 20 to 25 mm with <17 mm suggestive of RV dysfunction and <15 mm being considered significantly depressed (3). The angle of excursion is toward the cardiac apex, and is slightly greater than normal mitral annular plane excursion (1). The tricuspid annulus tilts toward the apex, whereas the mitral annulus moves more symmetrically toward the apex, somewhat like a piston, emphasizing the importance of measuring motion at the lateral tricuspid annulus (4). Depressed TAPSE measurements suggest depressed

RV systolic function from a variety of causes. TAPSE has been correlated to right ventricular ejection fraction (RVEF). However, it is important to note that TAPSE has several limitations in the intraoperative period. First the annular motion vector is oblique to the ME four-chamber view which results in angle-related errors. TAPSE is load dependent and not reliable after pericardiectomy. Also, it reflects only the longitudinal displacement of a single segment of the complex RV 3D structure (Fig. 14.8), and lastly, it does not assess lateral wall and RVOT contributions to ejection.






FIGURE 14.5 Eccentricity index. A, B: Using the transgastric mid short-axis view, the eccentricity index (EI) corresponds to the ratio of the vertical (V)/horizontal (H) diameter of the left ventricle (LV). C, D: In fluid overload, the H dimension is smaller than V dimension only during systole. E, F: In pressure overload, it remains smaller in both systole and diastole image (Videos 14.1 and 14.2). RV, right ventricle. (Reproduced from Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)






FIGURE 14.6 RV assessment. The right ventricular (RV) fractional area change (FAC) corresponds to the difference of the RV end-diastolic area (EDA) minus the RV end-systolic area (ESA) divided by the RV EDA. Tricuspid annular plane systolic excursion (TAPSE) represents the systolic excursion of the lateral tricuspid annulus. TAPSE can be measured from the change in the distance (arrow) in diastole between the apex and the lateral tricuspid annulus. Normal TAPSE should be >17 mm (3). LA, left atrium; LV, left ventricle; RA, right atrium. (Reproduced from Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)






FIGURE 14.7 Myocardial performance index (MPI). To calculate the MPI or Tei index of the left ventricle (LV), the transmitral flow is used for measurement of the duration “a” from the end of atrial contraction (A-wave) to the beginning of LV filling (E-wave). The ejection time (ET) or “b” is measured from a deep transgastric long-axis view Doppler interrogation of the left ventricular outflow tract. The MPI of the right ventricle (RV) is similarly obtained using the transtricuspid flow and the mid-esophageal ascending aorta short-axis view for the RV outflow tract. A, peak late diastolic TMF velocity; E, peak early diastolic TMF velocity; IVCT, isovolumic contraction time; IVRT, isovolumic relaxation time. (Reproduced from Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)


Tissue Doppler

Tissue Doppler peak velocity at the tricuspid annulus (S’) (Fig. 14.9) <9.5 cm/s is a sign of RV dysfunction as it represents the basal RV lateral wall function. RV acceleration during isovolumic acceleration (IVA) is also measured by TDI at the lateral tricuspid annulus. RVIVA is defined as the peak isovolumic myocardial velocity divided by time to peak velocity. This parameter is rate dependent and appears to be less load dependent than RVMPI. Value <2.2 m/s2 is considered to be related to RV dysfunction.


Assessment of Right Ventricular Diastolic Function

Presence of tricuspid regurgitation (TR) or irregular R-R intervals renders the analysis of diastolic dysfunction difficult immediately after CPB weaning. However, in the absence of these conditions, gradation of diastolic RV function can be achieved through transtricuspid flow (TTF) and hepatic venous flow (Fig. 14.10).


Transtricuspid Flow

Early- and late-filling wave velocities (E- and A-wave, respectively) and E deceleration time recorded by PWD in the TTF and the lateral tricuspid annulus velocity during early filling (E’) recorded by TDI allows diastolic categorization of RV function. A tricuspid E/A ratio <0.8 suggests impaired relaxation, a tricuspid E/A ratio of 0.8 to 2.1 with an E/E’ ratio >6 or diastolic flow predominance in the hepatic veins suggests pseudonormal filling, and a tricuspid E/A ratio >2.1 with a deceleration time <120 ms suggests restrictive filling (see Fig. 14.10) (11).


Right Ventricular Strain and Strain Rate

Deformation indices such as strain and strain rate have been shown to be useful parameters for estimating RV global and regional systolic function (2). Longitudinal strain is a percentage of systolic shortening of the RV lateral wall that should be measured in the RV-focused ME four-chamber view. This measurement is still dependent on RV loading conditions, RV size and shape. Peak global longitudinal strain of the RV lateral wall (also termed RV free wall strain in the literature) has been shown to be more sensitive and specific for detection of RV systolic dysfunction than other evaluation modalities (12). It has also been reported to have prognostic value in various disease states such as heart failure, acute myocardial infarction, pulmonary hypertension, and amyloidosis and to predict RV failure after LV assist device implantation. Current reference values have been published (2). Global longitudinal RV lateral wall strain >-20% is likely abnormal.


Three-Dimensional Right Ventricular Ejection Fraction

Three-dimensional (3D) echocardiographic RVEF is a global measure of RV systolic function and performance. This newer modality has been extensively validated against cardiovascular magnetic resonance (CMR) (2). It has been described as being of particular value in patients after cardiac surgery when conventional indices of RV function are generally reduced and no longer a real representation of the overall RV performance. The limitations of the 3D RVEF are load dependency, interventricular changes affecting septal motion (RV pacing), poor acoustic windows, and irregular rhythms. Keeping this in mind, the latest American Society of Echocardiography (ASE) guidelines on Chamber quantification published in 2015 recommend 3D RVEF as a method to quantify RV systolic function. An RVEF of <45% reflects abnormal RV systolic function. Limitation of 3D RVEF is that it is not available on real time in the most current TEE platform.


Assessment of Regional Right Ventricular Function

RV perfusion is supplied primarily by the right coronary artery, although a small portion of the anterior and infundibular wall may be supplied by a conus branch of the left anterior descending artery. Right coronary artery (RCA) is dominant in 85% of the population, which, in addition to supplying blood flow to the RV lateral

wall, supplies the inferior wall of the LV and the posterior third of the septum. In the minority of patients, the RCA is nondominant where the infundibular, anterior, and inferior wall are perfused from both right and left contribution. However, the lateral wall is only perfused by the RCA (13). Since the thin-walled RV is a volumedependent chamber, the RVEF is extremely sensitive to changes in afterload. In contrast, the thick-walled LV is a pressure-dependent chamber, and its LV ejection fraction (LVEF) is largely preserved over large changes in afterload demand. Furthermore, the irregularity and asymmetry of the RV make changes in inotropic function difficult to detect or quantify. More dramatic changes in function such as akinesia or dyskinesia are more readily identified and are sensitive indicators of RV infarction. Less common findings associated with RV infarction include RV dilation, papillary muscle dysfunction, TR, and paradoxic motion of the interventricular septum (4,14). It is important to mention also that the RV is perfused in both systole and diastole.






FIGURE 14.8 Tricuspid annular plane systolic excursion (TAPSE). A-E: Steps in the measurement of TAPSE using anatomic M-mode are shown. A, B: First a mid-esophageal four-chamber view is acquired and (C) the M-mode cursor is positioned along the plane of the TAPSE motion to obtain the M-mode image of this displacement (D). The lower point corresponds to the maximal systolic excursion and the upper point is the atrial contraction. E: The TAPSE is equal to the total systolic displacement of the tricuspid annulus which is normally 20 to 25 mm. F: Normal values from Lang et al. (2). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle image (Video 14.3). (Reproduced from Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)






FIGURE 14.9 Tissue Doppler imaging (TDI) for right ventricular function. A, B: Deep transgastric right ventricular inflow/outflow long-axis view allows the evaluation of both the pulsed wave Doppler interrogation of the tricuspid valve and TDI of the tricuspid annulus along the dotted line. C: Tissue Doppler signal obtained at the base of the tricuspid annulus image (Video 14.4). At, tricuspid late diastolic filling (during atrial contraction) tissue Doppler velocity; CPB, cardiopulmonary bypass; Et, tricuspid early diastolic filling tissue Doppler velocity; IVC, inferior vena cava; MPA, main pulmonary artery; PV, pulmonic valve; RA, right atrium; RV, right ventricle; St, tricuspid systolic tissue Doppler velocity; SVC, superior vena cava; TV, tricuspid valve. (Adapted with permission of Haddad F, Couture P, Tousignant C, Denault AY. The right ventricle in cardiac surgery, a perioperative perspective: I. Anatomy, physiology, and assessment. Anesth Analg 2009;108(2):407-421.)


Hemodynamic and Extracardiac Manifestation of Right Ventricular Dysfunction

The use of RV and RA pressure waveform monitoring (Fig. 14.11) is another method of detecting the appearance of RV dysfunction mostly diastolic (15). Interestingly, these waveforms do correlate with the extracardiac
consequences of RV dysfunction on intra-abdominal organs. Those elements can be identified using lower esophageal or TG TEE in order to interrogate hepatic, portal or splenic (16), and renal venous flow (17).






FIGURE 14.10 Right ventricular diastolic dysfunction (DD) algorithm. Diastolic function is classified by pulsed wave Doppler of the transtricuspid flow (TTF), hepatic venous flow (HVF) and tissue Doppler imaging of the tricuspid annular velocity (TAV). Patients with a pacemaker, atrial fibrillation, non-sinus rhythm, complete atrioventricular blockade, moderate to severe tricuspid regurgitation, and tricuspid annuloplasty are excluded from analysis. A, atrial component TTF; AR, atrial reversal HVF; At, atrial TAV; D, diastolic HVF; E, early-filling TTF; Et, early TAV; S, systolic HVF. (Reproduced from Denault AY, Couture P, Vegas A, et al. Transesophageal Echocardiography Multimedia Manual, Second Edition: A Perioperative Transdisciplinary Approach. New York: Informa Healthcare; 2011; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)


Hepatic Venous Flow Patterns

Examination of flow velocity patterns during phases of the cardiac cycle with PWD can contribute useful information about RV function. Normal hepatic flow is directed away from the liver to the RA and fluctuates during the cardiac cycle (Fig. 14.11C).

Normal hepatic venous flow patterns have four phasic components: AR corresponding to atrial reversal, S corresponding to ventricular contraction, translation of the tricuspid annulus toward RV apex, and D corresponding to early ventricular filling. Initial forward flow during systole is associated with atrial relaxation and apical movement of the TV during RV systole and corresponds to the x-descent in atrial pressure measurements. Subsequent diastolic flow, associated with early ventricular filling, corresponds to the y-descent. Two small retrograde hemodynamic waves are often detectable, corresponding to atrial contraction at enddiastole (A) and at end-systole a small V-wave corresponding to the end-systolic phase prior to the y-descent.

Systolic flow is usually of higher velocity than diastolic flow. This correlates with the x-descent being normally more important than the y-descent. This is due to the downward motion of the tricuspid annulus during ventricular systole resulting in a rapid filling of the RA. In patients with RV dysfunction, decreased

TAPSE and/or TR during ventricular systole lead to a reduction of the velocity in systole (S) and to a systolic-to-diastolic ratio less than 1 (S/D <1) as shown in Figure 14.11H. In severe RV failure or TR, the S-wave appears to be completely reversed with backward flow in the hepatic veins during systole rendering negative systolic-to-diastolic ratio (S/D <0) as shown in Figure 14.11M (18).






FIGURE 14.11 Right ventricular pressure (Prv), right atrial pressure, hepatic venous flow (HVF), portal venous flow and interlobar arterial and venous renal flow in normal patients (A, B, C, D, E) and typical patterns commonly observed in patients with mild (F, G, H, I, J) and severe (K, L, M, N, O) right ventricular dysfunction. AR, atrial reversal HVF velocity; D, diastolic HVF Doppler velocity; Ppa, pulmonary artery pressure; S, systolic HVF velocity. (Adapted from Amsallem M, Kuznetsova T, Hanneman K, et al. Right heart imaging in patients with heart failure: A tale of two ventricles. Curr Opin Cardiol 2016;31[5]:469-482; Tang WH, Kitai T. Intrarenal venous flow: A window into the congestive kidney failure phenotype of heart failure? JACC Heart Fail 2016;4[8]:683-686.)


Portal and Splenic Venous Flow Patterns

Flow in the portal or splenic veins can be assessed using TEE (16) but more easily with transthoracic echocardiography (TTE). The splenic vein is a direct tributary of the portal vein and thus its assessment could provide the same information. Imaging of the portal vein is accomplished by means of a TG short-axis cut of the liver by turning the probe on the right side of the patient. A multiplane angle rotation of 90° to 120° leads to a craniocaudal plane of the liver. The portal vein is usually within a few centimeters of the transducer and the inferior vena cava (IVC) is usually not included in the same 2D view (Fig. 14.12). Alternatively, assessment of splenic vein flow can also be done with TG scanning. This view can be obtained by turning the probe to the left side of the body and by performing a multiplane angle rotation of 90°. This will bring the view close to the splenic hilum. In this view, venous blood will travel in the direction of the probe and the velocities measured during Doppler examination will be positive (Fig. 14.13A-C). An alternative view can be obtained. With the probe toward the posterior aspect of the body, the electronic rotation angle is maintained at 0°. From this position, the splenic vein is located anterior to the descending aorta. From this view, the venous flow will be traveling away from the probe and the Doppler signal produced will exhibit negative velocities (Fig. 14.13D-F). The success rate for portal flow assessment using TEE has
not been systematically studied but is believed to be as good or better than portal flow assessment based on clinical experience.






FIGURE 14.12 Portal vein. A-C: Transesophageal echocardiography transgastric views with right-sided rotation shows the main branch of the right portal vein (RPV). Note the portal vein has a hyperechoic sheath around the vein as opposed to the inferior vena cava or the hepatic vein whose wall is barely seen. The hyperechoic sheath results from the proximity of the biliary duct and the hepatic artery which forms the portal triad. D: Pulsed wave Doppler of portal vein shows low-resistance continuous, monophasic low-velocity portal venous flow (PoVF) image (Video 14.5). (Reproduced from Denault A, Vegas A, Lamarche Y, et al. Basic Transesophageal and Critical Care Ultrasound. Taylor and Francis, CRC Press; 2018; with permission of Taylor and Francis Group, LLC, a division of Informa plc.)

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Apr 16, 2020 | Posted by in ANESTHESIA | Comments Off on Right Ventricle, Right Atrium, Tricuspid and Pulmonic Valves
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