Cardiac imaging

Introduction

Cardiac imaging has undergone significant advancements since the start of the 21st century. The last two decades have seen improvements in all imaging modalities used to visualize the heart, including echocardiography, cardiac computed tomography (CT), and cardiac magnetic resonance imaging (MRI). These advancements, including new equipment and techniques, offer better image quality, increased accuracy, and a wider range of capabilities. As a result, more sophisticated imaging options are now available for evaluating cardiac anatomy, ventricular function, and blood flow across valves, leading to a deeper understanding of coronary artery disease, heart failure, and structural heart diseases. The integration of artificial intelligence and machine learning in cardiac imaging has even led to the discovery of previously unnoticed disease patterns and a more personal approach to clinical care.

The evolution of cardiac imaging has also revolutionized the field of cardiac surgery by streamlining the preoperative planning phase and guiding complex procedures. Preoperatively, these imaging modalities are used to identify, quantify, and understand the underlying cardiac disease, informing surgical decisions. Intraoperative transesophageal echocardiography (TEE) provides real-time monitoring of underlying pathophysiology, guiding beating heart procedures, supporting surgical planning, and allowing for assessment of surgical results. Cardiac imaging is also crucial in the postoperative period to diagnose and manage complications. Lastly, noninvasive imaging is often employed to evaluate and monitor long-term surgical results.

Intraoperative TEE was first introduced in the 1980s, initially only for monitoring left ventricular (LV) function before and after coronary artery bypass grafting (CABG). Since then, echocardiography has become an essential tool for the preoperative and intraoperative management of patients undergoing a range of cardiac procedures. In the last two decades, three-dimensional (3D) echocardiography has emerged as a means of quantifying LV function and structural heart disease, offering more accurate and reproducible measurements of LV volumes and systolic function. In 2003, guidelines for the use of echocardiography, including TEE, were presented by the American College of Cardiology, American Society of Echocardiography (ASE), and American Heart Association, building on previous guidelines from the American Society of Anesthesiologists and Society of Cardiovascular Anesthesiologists (SCA). Echocardiography is now often the first choice for cardiac evaluation due to its high resolution, portability, affordability, and lack of radiation exposure.

Echocardiography

General principles

Echocardiographic images are constructed by transmitting high-frequency sound waves from a transducer composed of piezo-electric crystals. These waves reflect off cardiac structures, and the same transducer receives the returning signals. By knowing when the signal was sent, the speed of the sound in the tissue, and the time it takes for the reflected signal to return to the transducer, the position of the structure responsible for the reflection can be calculated. An image from these signals can thus be created. The quality of the image relies on many factors, including the media through which the sound is traveling, the orientation of the structures in relation to the ultrasound beam, and the composition of the structure. Sound travels incredibly well through water and blood, reasonably well through tissue, but poorly through air and bones. Therefore, echocardiographers use windows (between the ribs, sternum, and lungs) such as parasternal, apical, subcostal, suprasternal, transesophageal, or intracardiac to ensure good penetration of ultrasound. The fact that sound transmitted from a TEE transducer has less distance to travel (which means less signal lost to scatter) and mainly travels through muscle and blood (and rarely air) explains why the quality of TEE images is usually better than transthoracic echocardiography (TTE) imaging.

Echocardiographic displays include M-mode, two-dimensional (2D), and 3D imaging. The M-mode echocardiogram has superior temporal resolution and can be thought of as a display of the motion of a single cut through the heart over time ( Fig. 6.1 ). It is now used primarily to quantify the timing of intracardiac events.

A pair of M-mode views shows interventricular septum motion, left ventricular cavity changes, posterior wall motion, and mitral valve leaflet movement. The pair of M-mode views of the left ventricle and mitral valve shows 2 labeled panels with continuous motion patterns across the cardiac cycle. In panel A, the upper two-dimensional view shows the interventricular septum L V, and the left ventricle posterior wall beneath the cursor line. The M-mode tracing below shows parallel motion bands of the interventricular septum, the left ventricular cavity, and the left ventricular posterior wall with cyclical inward and outward excursions. The E C G tracing above shows repeating waveforms aligned with the M-mode sweep speed marker that states 75 millimeters per second. In panel B, the upper two-dimensional view shows the interventricular septum L V and the mitral valve beneath the cursor line with a labeled anterior mitral valve leaflet. The M-mode tracing shows the interventricular septum, the left ventricular cavity, and the anterior mitral valve leaflet, which moves in a repeated opening and closing pattern. A label identifies the anterior mitral valve leaflet along the leaflet excursion path. The E C G tracing above shows repeating waveforms aligned with the same sweep speed marker at 75 millimeters per second. — • Figure 6.1

Two-dimensional echocardiography ( Fig. 6.2 ) provides a display with better spatial resolution and excellent temporal resolution. Three-dimensional echocardiography provides the best display of the spatial relationships of various structures and flow patterns, and its resolution continues to improve.

A two-dimensional echocardiograph shows the right ventricle, the left ventricle, the left atrium, the left ventricle posterior wall, and the aortic valve. The two-dimensional echocardiographic view shows labeled cardiac chambers and valve structures. The label R V marks the right ventricle near the upper central region. The label L V marks the left ventricle in the mid region. The label L A marks the left atrium along the lower right region. The label L V P W marks the left ventricle posterior wall along the lower left border. A labeled aortic valve sits between the right ventricle and the left ventricle with an arrow pointing toward the leaflet region. Depth markers, along the right margin, and an E C G tracing span the lower margin with repeating waveforms. — • Figure 6.2

Doppler echocardiography and color flow imaging, which provide reliable hemodynamic assessment, not only have replaced many invasive hemodynamic procedures but can also be superior to them under certain circumstances. Intracardiac blood flow velocities and myocardial motion are assessed by the Doppler principle, first described by the Austrian physicist Christian Doppler in 1842. The wavelength of sound reflecting off moving blood particles will be shorter if blood is moving toward the transducer and longer if moving away. This difference in frequency, known as the Doppler shift, can be used in the calculation of blood velocity ( Fig. 6.3 ).

A diagram of a blood vessel shows a transducer beam path, R B C s, and labeled Doppler parameters. The diagram of a blood vessel shows extending diagonally with multiple labeled red blood cells moving in the direction of an arrow marked v. A transducer sits on the left with an outgoing arrow labeled f o and a returning arrow labeled f r aimed toward the vessel. An angle marker along the beam path carries the label theta. Text below lists Doppler shift equations: delta f equals f r minus f o and an expression that contains 2 f o times of v cos theta divided by c. Additional labels list f o as transmitted frequency, f r as reflected frequency, v as velocity of red blood cells, and c as speed of ultrasound in blood. — • Figure 6.3

The angle of the ultrasound beam and the direction of blood flow are critically important in this calculation; thus, the beam should be aligned as parallel to the blood flow as possible. Several modalities of Doppler echocardiography can be used. Pulsed wave (PW) Doppler has excellent spatial resolution, permitting sampling of local blood flow velocities at a specific region (sample volume). This modality is particularly useful for assessing the relatively low-velocity flows associated with LV outflow tract, pulmonary venous flow, or left atrial appendage flow ( Fig. 6.4 ).

A pair of pulsed wave Doppler views of blood flow along the aortic valve and left ventricular tract, labeled A and B, shows waveforms with two-dimensional sampling windows, and E C G tracings. The pair of pulsed wave Doppler views, labeled A and B involve blood flow in the aortic valve and left ventricular tract. In panel A, the upper two-dimensional sector depicts a sampling cursor positioned within the cardiac outflow region with depth markers along the right margin. An E C G tracing spans the top of the spectral display. The Doppler spectral waveform below shows repeated sharp systolic peaks that extend toward the negative velocity scale with centimeter per second markings along the right side. Machine settings are present along the left edge, including P W 50 percent W F 150 hertz, S V 4.0 millimeters, 1.6 megahertz, and 12.2 centimeters. A sweep speed marker at the bottom states 50 millimeters per second. In panel B, the upper two-dimensional sector contains the sampling cursor within the outflow region with depth markers along the right margin. An E C G tracing with repetitive waveforms lies above the spectral display. The Doppler spectral waveform shows broad systolic peaks extending toward the negative velocity scale. Machine settings appear along the left edge, including C F 55 percent 3838 hertz, W F 383 hertz 2.5 megahertz and P W 42 percent W F 125 hertz S V 4.0 millimeters 1.6 megahertz and 11.1 centimeters. A sweep speed marker at the bottom states 75 millimeters per second. — • Figure 6.4

Continuous wave Doppler records signal along the entire length of the ultrasound beam and permits measurement of very high velocities, such as in aortic stenosis ( Fig. 6.5 ).

A pair of continuous wave Doppler views labeled A and B shows aortic stenosis and tricuspid regurgitation with spectral velocity waveforms two two-dimensional alignment lines, and E C G tracings. The pair of continuous wave Doppler views contains 2 panels labeled A and B. In panel A, the upper two-dimensional sector of aortic stenosis depicts the cardiac outflow region. Depth markers appear along the right margin. An E C G tracing spans the top of the spectral display. The Doppler spectral waveform shows tall symmetric systolic envelopes extending across the positive and negative velocity scale. Machine settings appear along the left side, including F R 61 hertz 15 centimeters two-dimensional 55 percent C 52 P low and H Pen. Additional settings near the spectral display list C W 60 percent 1.8 megahertz and W F 225 hertz. A sweep speed marker at the bottom states 75 millimeters per second with a heart rate of 66 beats per minute. In panel B, the upper two-dimensional sector shows the sampling cursor aligned through the regurgitant jet with depth markers along the right margin. A velocity box near the top lists velocity equals 2.90 meters per second, and P G equals 33.8 millimeters of mercury. An E C G tracing runs above the spectral display. The Doppler spectral waveform shows broad systolic envelopes that extend deeply into the negative velocity scale with centimeter per second markings along the right side. Machine settings on the left list 22 hertz, 15 centimeters, two-dimensional 65 percent C 50 P low H Pen C F 50 percent, 4150 hertz W F 414 hertz, 2.5 megahertz, and C W 55 percent W F 256 hertz, and 1.8 megahertz. A sweep speed marker at the bottom states 75 millimeters per second with a heart rate of 103 beats per minute. — • Figure 6.5

Doppler color flow imaging is typically used in the assessment of regurgitant flows, and velocities and directions of the flow are displayed using a color scale ( Fig. 6.6 ).

A pair of apical three-chamber Doppler views of left ventricular flow, labeled A and B, shows two-dimensional sectors, colour flow regions, sampling cursors, and E C G tracing. The pair of apical three-chamber Doppler views shows left ventricular labeled A and B. In panel A, a two-dimensional sector occupies the center with a broad color flow region filling the chamber from base to apex. The left side lists settings including M G H X5-120 hertz 15 centimeters, two-dimensional 69 percent C 50 P low and H Res. A colour flow scale with centimeter per second markings lies along the right margin. Depth markers are present along the right border of the sector. An E C G tracing runs along the lower margin with repeated waveforms. In panel B, the two-dimensional sector contains a tapered color flow jet directed toward the outflow region. A small outline drawing is present in the upper right corner. A vertical velocity scale with centimeters per second markings lies along the right margin. Depth markers are present along the right border of the sector. A sampling cursor marked X lies along the right side of the field. — • Figure 6.6

However, it must be remembered that the color display represents the velocity, and not the volume, of the regurgitant blood, as one would see on an angiogram.

Transthoracic echocardiography

Standard views.

TTE is a widely available, reproducible, noninvasive ultrasound imaging modality, often used as a first-line cardiac imaging modality. Comprehensive echocardiographic examination typically involves integrating imaging of the heart from multiple orientations to fully visualize cardiac structures. There are four standard transducer positions: the parasternal, apical, subcostal, and suprasternal windows ( Fig. 6.7 ).

A pair of illustrations labeled A and B shows cardiac planes and standard transthoracic transducer windows with labeled anatomic orientations. The pair of illustrations of heart planes and transducer windows is labeled A and B. Panel A shows a three-dimensional heart illustration with intersecting planes labeled long axis plane, short axis plane, and apical plane. Orientation markers surround the heart with superior, anterior, lateral, inferior, posterior, and medial labeled around the perimeter. The planes pass through the heart at different angles and positions. Panel B shows an illustration of the upper thorax labeled with transthoracic transducer windows. A suprasternal notch sits at the top. Below it, the aorta is labeled A O, and the pulmonary artery is labeled P A. The right atrium is labeled R A, the right ventricle is labeled R V, and the left ventricle is labeled L V. Labeled positions include right parasternal, right apical, and subcostal. Curved contours outline the approximate acoustic windows along the chest. — • Figure 6.7

Parasternal long-axis (PLAX) view.

The TTE examination usually begins with the patient in the left lateral decubitus position and by placing the transducer in the left parasternal region, usually in the third or fourth left intercostal space. From this position, images can be acquired along the long and short axes ( Fig. 6.8 ).

A layout involves a photograph of an anatomic specimen of the heart labeled A and a parasternal long-axis echocardiographic view labeled B involving cardiac chambers, walls, and outflow structures. The layout involves a photograph of an anatomic specimen of the heart and parasternal long-axis echocardiographic views contain 2 labeled panels marked A and B. In panel A, the anatomical cross-section of the heart depicts internal chamber contours and valve openings with the ventricular and atrial cavities exposed. In panel B, a parasternal long-axis two-dimensional view depicts labeled cardiac structures. The right ventricle is labeled R V near the top. The interventricular septum is labeled I V S. The left ventricle is labeled L V. The posterior wall thickness is labeled P W T along the lower border of the left ventricle. The left atrium is labeled L A toward the right side. The left ventricular outflow tract is labeled L V O T, leading toward the structure labeled A o, which marks the aorta. Depth markers lie along the right margin, and an E C G tracing spans the lower margin with repeating waveforms. — • Figure 6.8

Parasternal short-axis (PSAX) view.

After acquiring the PLAX images, PSAX views of the heart are obtained by rotating the transducer clockwise ( Fig. 6.9 ).

A pair of parasternal short-axis views of the heart shows the right ventricular outflow tract, the pulmonary artery, and the right and left pulmonary arteries. The pair of parasternal short-axis views is arranged side-by-side. In the left panel, the parasternal short-axis sector shows the region labeled R V O T in the upper portion. The structure labeled P A occupies the central region. The labels Right P A and Left P A appear along the branching vessels. Depth markers lie along the right margin, and an E C G tracing spans the lower margin. In the right panel, a schematic overlay shows labeled cardiac structures within the same acoustic window. The right atrium is labeled R A. The aortic valve is labeled A V. The pulmonary valve is labeled P V. The pulmonary artery is labeled P A, with branching vessels labeled R P A and L P A. The right ventricular outflow tract is labeled R V O T along the superior right side. The schematic aligns with the underlying sector boundaries and depth markers. — • Figure 6.9

Superior and inferior transducer manipulations permit the demonstration of cardiac structures at the base (aortic valve), basal LV (mitral valve), mid-LV (papillary muscle), and apical LV levels ( Figs. 6.10 , 6.11 , and 6.12 ).

A pair of parasternal short-axis views shows the aortic valve, the atria, the tricuspid valve, the right ventricular outflow tract, the pulmonary valve, and the interatrial septum. The pair of parasternal short-axis views is stacked side-by-side. In the left panel, the parasternal short-axis sector shows labeled cardiac structures. The right ventricular outflow tract is labeled R V O T near the top. The right atrium is labeled R A on the left side. The left atrium is labeled L A on the lower right. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In the right panel, a schematic overlay shows the same anatomic relationships. The aortic valve is labeled A V in the upper center. The pulmonary valve is labeled P V along the right side. The tricuspid valve is labeled T V to the upper left. The right ventricular outflow tract is labeled R V O T. The right atrium is labeled R A, and the left atrium is labeled L A. The interatrial septum is labeled I A S near the lower center. — • Figure 6.10

A pair of parasternal short-axis views shows the aortic valve region with labeled right and left coronary artery origins. The pair of parasternal short-axis views is arranged side-by-side. In the left panel, the parasternal short-axis sector shows the level of the aortic valve with 2 labeled coronary artery origins. An arrow points to the region labeled R C A near the upper portion of the valve. A second arrow points to the region labeled L C A along the lower portion. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In the right panel, a schematic overlay shows the same anatomic level. The aortic valve leaflets and sinus contours are depicted. The right coronary artery origin is labeled R C A, and the left coronary artery origin is labeled L C A. The schematic aligns with the underlying sector boundaries and depth markers. — • Figure 6.11

A series of six parasternal short-axis views with overlapped schematics labeled A through F shows the left ventricle at the mitral valve level, the papillary muscle level, and the apical level. The series of six parasternal short-axis views with overlapped schematics is arranged in three rows labeled A through F. The top left panel A, the parasternal short-axis sector, shows the left ventricle at the mitral valve level with the mitral orifice forming a circular opening. A cross-section of the right ventricle lies superiorly. An E C G tracing spans the lower margin. The top right panel B, the schematic overlay shows the same orientation with the right ventricle labeled R V and the circular mitral orifice outlined within the left ventricle. The middle left panel C, the parasternal short-axis view shows the left ventricle at the papillary muscle level. Two papillary muscles are labeled as the anterior lateral papillary muscle and the posterior medial papillary muscle. The right ventricle lies superiorly. The middle right panel D, the schematic overlay shows the right ventricle labeled R V and two papillary muscles positioned within the left ventricular cavity. The bottom left panel E, an inferior parasternal short-axis view, shows the left ventricle at the apical segments with a smaller circular cavity. The right ventricle cross-section remains present above. The bottom right panel F, the schematic overlay shows the same circular apical level with a central left ventricular cavity and surrounding myocardium, aligned with the sector boundaries and depth markers. — • Figure 6.12

Parasternal views are used for the assessment of LV wall motion and coronary artery disease ( Fig. 6.13 ).

A set of illustrations involves myocardial segments labeled with distributions of R C A, L A D, and C X territories. The set of illustrations involves myocardial segments with labeled distributions of R C A, L A D, and C X territories across multiple ventricular views. The left side depicts a heart illustration with coronary pathways marked for R C A, L A D, C X, and overlapping regions. The right side depicts three vertical ventricular outlines with myocardial segments designated for R C A, L A D, C X, and shared distributions along the ventricular walls. Beneath these, three short-axis ventricular sections depict corresponding segmental territories divided into labeled regions for R C A, L A D, C X, and combined supply patterns. — • Figure 6.13

Apical views.

The next set of images is acquired from the apical window ( Figs. 6.14 , 6.15 , and 6.16 ).

A layout involves a pair of apical echocardiographic views with a corresponding schematic, and a photograph of a gross specimen of the heart shows ventricles, the atria, the valves, and the septa. The layout involves a pair of apical four-chamber echocardiographic views and a photograph of a gross specimen of the heart. In the upper left panel, the two-dimensional sector shows labeled chambers. The right ventricle is labeled R V on the upper left. The left ventricle is labeled L V on the upper right. The right atrium is labeled R A on the lower left, and the left atrium is labeled L A on the lower right. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In the upper right panel, a schematic overlay shows corresponding labeled structures. The right ventricle is labeled R V, the left ventricle is labeled L V, the right atrium is labeled R A, and the left atrium is labeled L A. The interventricular septum is labeled I V S between the ventricles, and the interatrial septum is labeled I A S between the atria. The tricuspid valve is labeled T V, and the mitral valve is labeled M V. In the lower panel, a photograph of a gross specimen shows an anatomic cross-section oriented in the apical four-chamber plane with ventricular cavities, atrial cavities, and internal trabecular structures. — • Figure 6.14

A set of four apical five-chamber views with Doppler and schematic labeled A through D shows the left ventricular outflow tract, the aortic valve cusps, the ventricles, and the atrium. The set of four apical five-chamber views is labeled A through D, arranged in two rows. The upper left panel A, the sector view shows the left ventricle labeled L V, the left ventricular outflow tract labeled L V O T, the left atrium labeled L A, and the ascending aorta labeled A s c A o. The upper right panel B, the same view with Doppler color overlay shows flow within the left ventricular outflow tract. The left ventricle is labeled L V, and the left atrium is labeled L A. Depth markers lie along the right border, and an E C G tracing spans the lower margin. The lower left panel C, a schematic overlay, shows labeled structures. The interventricular septum is labeled I V S. The right ventricle is labeled R V, and the left ventricle is labeled L V. The left ventricular outflow tract is labeled L V O T. The aorta is labeled A o, and the left atrium is labeled L A. The lower right panel D, a greyscale sector view, shows labeled structures. The right ventricle is labeled R V on the left side, the left ventricle is labeled L V on the upper right, the left ventricular outflow tract is labeled L V O T in the center, the aorta is labeled A o, and the left atrium is labeled L A along the lower right. An E C G tracing spans the lower margin of all four panels. — • Figure 6.15

A set of four panels involving apical long-axis and two-chamber echocardiographic views shows the left ventricle, the left atrium, the left ventricular outflow tract, aortic and mitral valves. The set of four apical long-axis and apical two-chamber echocardiographic views is labeled A through D. The upper left panel A, the apical long axis sector shows the left ventricle with an elongated cavity, the left ventricular outflow tract leading toward the aorta, and the left atrium positioned posteriorly. An E C G tracing spans the lower margin. The upper right panel B, a schematic overlay shows labeled structures. The left ventricle is labeled L V. The mitral valve is labeled M V. The left ventricular outflow tract is labeled L V O T. The aortic valve is labeled A V, and the aorta is labeled Aorta. The left atrium is labeled L A. The lower left panel C, the apical two-chamber sector, shows the left ventricle in a more anterior to inferior orientation. The left atrium occupies the posterior portion, and an E C G tracing spans the lower margin. The lower right panel D, a schematic overlay shows the same two-chamber orientation. The left ventricle is labeled L V, the mitral valve is labeled M V, and the left atrium is labeled L A. — • Figure 6.16

Subcostal views.

The subcostal views are obtained by placing the transducer in the midline, with the patient supine. This position allows visualization of the liver parenchyma, hepatic vessels, and inferior vena cava (IVC), as well as of the right ventricle (RV), the inferior interventricular septum, and anterolateral LV walls ( Fig. 6.17 ).

A set of four subcostal four-chamber views labeled A through D shows the atria, the ventricles, the valves, the septa, and the inferior vena cava. The set of four subcostal four-chamber views labeled A through D. The upper left panel A, the subcostal four-chamber sector shows labeled chambers. The right atrium is labeled R A on the left. The right ventricle is labeled R V above it. The left ventricle is labeled L V on the right, and the left atrium is labeled L A beneath it. Depth markers lie along the right border, and an E C G tracing spans the lower margin. The upper right panel B, a schematic overlay, shows corresponding labeled structures. The right atrium is labeled R A, the right ventricle is labeled R V, and the left ventricle is labeled L V. The left atrium is labeled L A. The tricuspid valve is labeled T V. The mitral valve is labeled M V. The interventricular septum is labeled I V S, and the interatrial septum is labeled I A S. The lower left panel C, the subcostal view, is angled toward the inferior vena cava. An arrow points to the vessel labeled I V C entering the right atrium labeled R A. Depth markers lie along the right border, and an E C G tracing spans the bottom. The lower right panel D, a schematic overlay, shows the same orientation. The liver is labeled Liver above the field. The inferior vena cava is labeled I V C, and the right atrium is labeled R A. — • Figure 6.17

Based on the diameter and the collapsibility with respiration or sniff of the IVC ( Fig. 6.18 ), right atrial pressure (RAP) is estimated. The subcostal four-chamber view is also very useful for visualizing anterior pericardial effusions.

An M-mode echocardiographic view shows the inferior vena cava with respiratory motion recorded through inspiration and expiration. The M-mode echocardiographic view shows the inferior vena cava motion across the respiratory cycle. A two-dimensional sector at the top depicts the sampling cursor aligned with the vessel. The M-mode tracing beneath shows repeating undulating patterns of the inferior vena cava walls as they move with inspiration and expiration. Depth markers lie along the right border, and an E C G tracing spans the upper portion of the display with repeated waveforms. The word S N I F F is labeled in upper case on the left side above the spectral band. — • Figure 6.18

Suprasternal notch.

For visualization of the distal ascending, transverse, and proximal descending aorta, as well as the left aortic arch, the transducer is positioned in the suprasternal notch. The take-off of the great vessels may also be appreciated ( Figs. 6.19 and 6.20 ).

A pair of suprasternal short-axis views labeled A and B shows the left brachiocephalic vein, the superior vena cava, the aorta, and the right pulmonary artery. The pair of suprasternal short-axis views is labeled A and B. In the upper panel, the sector view shows the aorta labeled A o in cross-section near the center. The superior vena cava is labeled S V C and lies anterior to the aorta. A vessel labeled L innom Vein extends from the upper right toward the superior vena cava. The right pulmonary artery is labeled R P A and sits posterior to the aorta. Depth markers lie along the right margin, and an E C G tracing spans the lower margin. In the lower panel, a schematic overlay outlines these same structures. The aorta is labeled A o, the superior vena cava is labeled S V C, the left brachiocephalic vein is labeled L Brac Vein, and the right pulmonary artery is labeled R P A. The schematic aligns with the underlying short-axis sector. — • Figure 6.20

Basic measurements.

As seen in Fig. 6.21 , standard 2D measurements of the left ventricle are made at end-diastole and end-systole. Additional measurements include left atrial dimension and aortic root diameters at three levels ( Fig. 6.22 ).

A pair of echocardiographs labeled A and B shows end diastolic and end systolic chamber dimensions with arrows marking septal thickness, cavity size, wall thickness, and right ventricular diameter. The pair of echocardiographs labeled A and B involves two-dimensional measurements. In the left panel labeled A, four numbered arrows mark standard end diastolic measurements. Arrow 1 points to the interventricular septum for I V S thickness. Arrow 2 spans the left ventricular cavity for the L V dimension. Arrow 3 marks the posterior wall for posterior wall thickness. Arrow 4 extends from the upper region for the R V diameter. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In the right panel labeled B, a single arrow marks the end systolic measurement. The arrow extends across the left ventricle for the L V end end-systolic dimension. Depth markers lie along the right border, and an E C G tracing spans the lower margin. — • Figure 6.21

A set of two echocardiographs, labeled A and B, shows the left atrial dimension and the aortic dimensions at three anatomical levels. The set of two echocardiographs labeled A and B shows cardiac chambers and valves. In panel A on the left, a sector view shows a single double-headed arrow extending across the left atrium, marking the left atrial dimension. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In panel B on the right, three vertical double-headed arrows mark aortic measurements. Arrow 1 marks the sinus of Valsalva. Arrow 2 marks the sinutubular junction. Arrow 3 marks the ascending aorta. Depth markers lie along the right border, and an E C G tracing spans the lower margin. — • Figure 6.22

Calculation of left ventricular ejection fraction.

The quantification of cardiac function is fundamental to cardiac imaging, with echocardiography being the most commonly used noninvasive modality. Left ventricular ejection fraction (LVEF) is the most commonly reported measure of global LV systolic function. However, it should be emphasized that echocardiography allows for the assessment of various components of global LV function, including global longitudinal strain (GLS), stroke volume, cardiac index, and regional wall motion analysis.

Several methods have been proposed for the quantitative assessment of LVEF. A qualitative visual assessment (“eyeballing”) of LVEF is reasonably reliable when performed by an experienced echocardiographer but has a considerable interobserver variation. The Teichholz method is often used in clinical practice for LVEF calculation. LV volume is calculated using only LV diameter (D) measured in the single dimension, as seen in Fig. 6.23 .

LV volume = 7D ³ /(2.4 + D)

A set of two echocardiographs labeled A and B shows the end-diastolic and end-systolic dimensions of the left ventricle. The set of two echocardiographs, labeled A and B, shows heart chambers. In panel A on the left, a double-headed arrow marked end diastole spans the width of the left ventricle when the cavity is at its maximum size. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In panel B on the right, double headed arrow marked end systole spans the same area when the heart muscle is contracted, and the cavity is at its minimum size. Depth markers lie along the right border, and an E C G tracing spans the lower margin. — • Figure 6.23

This method is simple, but its accuracy depends on geometric assumptions about LV shape; therefore, it is not useful in cases of wall motion abnormalities or cardiomyopathy. Therefore, whenever possible, the LVEF should be measured more objectively by using volumetric measurements. The biplane method of discs (modified Simpson method) using area tracings of the LV cavity is the currently recommended 2D method for the measurement of LVEF ( Fig. 6.24 ).

A layout involves a pair of pathologic views and a pair of echocardiographic set shows left ventricular border tracing at the compacted and noncompacted interface for volume assessment. The layout involves a pathologic and echocardiographic set that shows four panels arranged in two rows, demonstrating left ventricular border tracing at the boundary between compacted and noncompacted myocardium. In the upper left panel, a pathologic cross-section of the left ventricle shows an outlined contour that follows the interface between compacted myocardium and the noncompacted trabeculated layer. In the upper right panel, an apical four-chamber echocardiographic view shows the left ventricular cavity traced with a striped fill pattern, and a numerical display above lists L V area d A 4 C equals 37.41 square centimeters, L V major d A 4 C equals 8.48 centimeters, and L V vol d M O D A 4 C equals 138.2 milliliters. In the lower left panel, a second pathologic section shows a larger diastolic cavity with a contour that again follows the compacted inter along the ventricular wall. In the lower right panel, an apical four chamber echocardiographic view shows the left ventricular cavity traced with a striped fill pattern during systole, and a numerical display above lists L V area d A 4 C equals 44.91 square centimeters, L V major d A 4 C equals 10.24 centimeters, and L V vol d M O D A 4 C equals 167.1 milliliters. It also involves an upper case letter Q on the left side of the scan. An E C G tracing spans the lower portion of both echocardiographic panels. — • Figure 6.24

Ejection fraction (EF) is calculated from end-diastolic volume (EDV) and end-systolic volume (ESV) estimates using the following formula: EF = (EDV − ESV)/EDV .

Assessment of right atrial pressure and right ventricular systolic pressure.

RAP is estimated by measuring the diameter and degree of collapsibility of the IVC imaged from the subcostal view during inspiration ( Table 6.1 , Fig. 6.25 ).

TABLE 6.1

Right Atrial Pressures Estimated by IVC Diameter and Collapse

	RAP	IVC diameter	Collapse during sniff
Normal	3 mmHg	≤2.1 cm	>50%
Intermediate	8 mmHg	All the rest
Elevated	15 mmHg	>2.1 cm	<50%

A pair of subcostal views labeled A and B shows the inferior vena cava diameter in one frame and its collapse with inspiration in the next frame. The pair of subcostal views labeled A and B, arranged side-by-side. In panel A on the left, the subcostal sector shows the inferior vena cava entering the right atrial region. The vessel is rounded with a wider diameter. Depth markers lie along the right border, and an E C G tracing spans the lower margin. In panel B on the right, the same subcostal orientation shows the inferior vena cava during inspiration. The vessel is markedly narrower, demonstrating a collapse in caliber. Depth markers lie along the right border, and an E C G tracing spans the lower margin. — • Figure 6.25

The gradient estimated by the peak tricuspid regurgitation velocity (TRV) measured by continuous wave Doppler ( Fig. 6.25 B) reflects the pressure difference during systole between the RV and the right atrium (RA). Using the simplified Bernoulli equation (ΔP = 4V2) and the RAP, one can calculate the right ventricular systolic pressure (RVSP) with the following equation : RVSP = 4 (peak TRV ² ) + RAP . In the absence of right ventricular outflow obstruction, the RVSP is equivalent to pulmonary artery systolic pressure (PASP).

Intraoperative transesophageal echocardiography

The use of intraoperative TEE began in 1971, with the measurement of flow in the aortic arch, followed by the use of M-mode and 2D imaging. Since then, TEE has become the main imaging modality in the operating room and a critical component in surgical planning and timely assessment of surgical intervention. It also enables the determination of LV systolic function early after cardiopulmonary bypass (CPB) and provides an opportunity to correct suboptimal surgical results before leaving the operating room. For example, intraoperative TEE has particular prognostic importance in patients undergoing mitral valve (MV) repair and can help identify the need for additional pump runs as a result of findings.

TEE provides superior quality in imaging of the heart and great vessels owing to excellent ultrasound penetration from the esophagus. The probe location directly behind the heart and associated structures allows for better image resolution and avoidance of transthoracic imaging artifacts. Since its initial development, the field of TEE has improved significantly, and the current TEE transducer is flexible, better controlled, and provides up to 28 views, ^, utilizing four levels of imaging ( Fig. 6.26 ). Standard TEE views are illustrated in Figs. 6.27-6.35 .

An illustration of the heart shows four transesophageal echocardiography probe levels around the heart. The illustration shows the heart with four labeled probe positions arranged along the esophagus and stomach. The upper esophageal level is labeled U E near the top of the esophageal tract. The midesophageal level is labeled M E at the mid portion. The transgastric level is labeled T G near the stomach. The deep transgastric level is labeled D T G at the lowest point. Colored plane segments extend from each position to indicate corresponding imaging orientations. A boxed list on the right repeats the labels U E, M E, T G, and D T G in vertical order. — • Figure 6.26

A layout involves six panels organized in a table that shows midesophageal four-chamber and two-chamber views with labeled cardiac structures. The layout involves six panels organized in a table with two rows and four columns. The first row is labeled with the midesophageal four-chamber, and the second row is labeled with the two-chamber views with labeled cardiac structures, including the right atrium, left atrium, tricuspid valve septal leaflet, tricuspid valve anterior leaflet, mitral valve posterior leaflet, mitral valve anterior leaflet, and coronary sinus. The four-chamber row depicts a schematic heart orientation on the left, a central transesophageal echocardiographic view with labels for R A, L A, T V S L, T V A L, M V P L, and M V A L, and an unlabeled echocardiographic view on the right shows the same chamber configuration. The two-chamber row depicts a schematic heart orientation on the left, a central labeled transesophageal echocardiographic view with labels for L A, C S, M V-P L, M V-A L, and additional labels including L A A, I, and A, and an unlabeled two-chamber echocardiographic view on the right that shows the same chamber alignment without annotations. — • Figure 6.27

A layout involves six panels organized in a table that shows midesophageal mitral commissural and long-axis views with labeled cardiac structures. The layout involves six panels organized in a table with two rows and four columns. The first row is labeled with the midesophageal mitral commissural, and the second row is labeled with the midesophageal long-axis views. The mitral commissural row depicts a schematic heart illustration on the left, a central transesophageal echocardiographic view with labels mitral valve posterior leaflet M V P L, left atrium L A, circumflex coronary artery C X, anterolateral papillary muscle A L P m, and posteromedial papillary muscle P M P m, and an unlabeled echocardiographic view on the right that shows the same commissural plane. The long-axis row depicts a schematic heart orientation on the left, a central labeled transesophageal echocardiographic view identifying mitral valve posterior leaflet M V P L, aortic valve A V, left ventricular outflow tract L V O T, and left ventricle L V, along with mitral valve M V. The unlabeled echocardiographic view on the right shows the corresponding long-axis configuration. — • Figure 6.28

A layout involves three panels in a row shows midesophageal aortic valve short axis-view with labeled cardiac structures. The layout involves three panels in a row, labeled with a midesophageal aortic valve short-axis view. A schematic illustration on the left, followed by a central transesophageal echocardiographic view with labels for interatrial septum I A, right atrium R A, left atrium L A, noncoronary cusp N C C, left coronary cusp L C C, and right coronary cusp R C C arranged around the aortic valve. An unlabeled echocardiographic closing view on the right shows the same short-axis configuration of the aortic valve without annotations. — • Figure 6.29

A layout involves six panels organized in a table that shows the midesophageal aortic valve long-axis and bicaval views with labeled cardiac structures. The layout involves six panels organized in a table with two rows and four columns. The first row is labeled with the midesophageal aortic valve long-axis, and the second row is labeled with bicaval views. The long-axis row depicts a schematic heart orientation on the left, a central transesophageal echocardiographic view labeled with mitral valve anterior leaflet M V A L, mitral valve posterior leaflet M V P L, left ventricular outflow tract L V O T, ascending aorta A A, aortic valve A V, and the aortic root and A V anulus. The two unlabeled echocardiographic views on the right show the same long-axis configuration. The bicaval row shows a schematic heart orientation on the left, a central transesophageal echocardiographic view with labels for interatrial septum I A, left atrium L A, superior vena cava S V C, inferior vena cava I V C, eustachian valve E V, crista terminalis C T, and right atrial appendage R A A, and an unlabeled echocardiographic view on the right depicting the same bicaval alignment. — • Figure 6.30

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Tags: Judy Hung, Kirklin/Barratt-Boyes Cardiac Surgery

Apr 21, 2026 | Posted by drzezo in CARDIAC SURGERY | Comments Off

Thoracic Key

Fastest Thoracic Insight Engine

Cardiac imaging

Introduction

Echocardiography

General principles

Transthoracic echocardiography

Standard views.

Parasternal long-axis (PLAX) view.

Parasternal short-axis (PSAX) view.

Apical views.

Subcostal views.

Suprasternal notch.

Basic measurements.

Calculation of left ventricular ejection fraction.

Assessment of right atrial pressure and right ventricular systolic pressure.

Intraoperative transesophageal echocardiography

Related

Stay updated, free articles. Join our Telegram channel

Full access? Get Clinical Tree

Thoracic Key

Fastest Thoracic Insight Engine

Cardiac imaging

Introduction

Echocardiography

General principles

Transthoracic echocardiography

Standard views.

Parasternal long-axis (PLAX) view.

Parasternal short-axis (PSAX) view.

Apical views.

Subcostal views.

Suprasternal notch.

Basic measurements.

Calculation of left ventricular ejection fraction.

Assessment of right atrial pressure and right ventricular systolic pressure.

Intraoperative transesophageal echocardiography

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