ENDOCARDITIS SYMPOSIUM
Diagnosis and Medical Management of Infective Endocarditis: Transthoracic and Transesophageal Echocardiography MARTIN ST. JOHN SUTTON, M.R.C.P. AND RICHARD T. LEE, M.D.
Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
ABSTRACT The use of echocardiography in the diagnosis of vegetative endocarditis has been a keystone in the diagnosis and treatment of this important clinical syndrome. In addition, with the use of transesophageal echo this modality has now made important advances in not only diagnosis but in evaluation of global cardiac function. A considerable amount of information has been gathered on the vegetation and these data will be discussed.
In the early days of echocardiography, ultrasound was very helpful in making the diagnosis of vegetative endocarditis, but there have been many major technological advances since then. One of the questions that the surgeons are asking and that we ask ourselves as echocardiographers is not simply establishing the diagnosis, but ,how to assess the severity of the valvular lesions hemodynamically. In addition, we want to know how to evaluate the lesion through longterm follow-up and how ultrasound information can be used to ensure that patients are in an optimal hemodynamic state prior to surgery. Figure 1 is a two-dimensional echocardiogram from a young man with a history of intravenous drug abuse. A typical mass of vegetations is apparent on the mitral valve, prolapsing into the left atrium. This appearance is classic for mitral Presented at the Workshop on Surgery of Native and Prosthetic Valve Endocarditis. Boston, Massachusetts, May 6, 1989. Sponsored by the German Heart Center, Berlin, West Germany. Address for correspondence: Richard T. Lee, M.D., Director, Echocardiography Laboratory, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 021 15.
Vol. 5, No. 1, 1990
valve endocarditis. A simple way of assessing the severity of regurgitant valve lesions is by Doppler flow mapping. In mitral regurgitation, this entails delineating the area within the left atrium where the high velocity regurgitant jet can be detected. Doppler flow mapping can be performed with pulsed-wave Doppler or more easily with color flow Doppler. Color flow Doppler echocardiography demonstrated a large regurgitant jet of blood in the left atrium during systole in this patient. While the size of a color Doppler jet only roughly corresponds to the volume of regurgitation, it was apparent that the patient in Figure 1 had severe regurgitation that eventually required surgery. . Doppler ultrasound also provides hemodynamic information. The velocity of blood flow (V) is quadratically related to pressure (P). This is defined by the modified Bernoulli equation, in which the pressure gradient P = 4 (VXV). The type of hemodynamic information that can be derived from Doppler is illustrated by the patient in Figure 2. A large mass can be seen on the aortic valve, prolapsing into the left ventricular outflow tract. In Figure 3, the continuous-wave Doppler recording from this patient is shown. A high
Journal of Cardiac Surgery
39
SUTTON
Figure 1. Parasternal long-axis view from a patient with mitral valve endocarditis. The arrow points to a large vegetation prolapsing into the left atrium during systole.
velocity holo-diastolic signal of aortic insufficiency is seen. The instantaneous velocity of the regurgitant blood correlates with the magnitude of the pressure gradient throughout diastole. The difference between the aortic diastolic pressure and left ventricular diastolic pressure can be determined by using the modified Bernoulli equation. When aortic diastolic pressure is low and there is significant elevation of left ventricular end-diastolic pressure, the velocity at end-diastole is small. The slope of the velocity signal or the rate of velocity decay can be used to measure the pressure half-time. The pressure half-time is the time interval during which the pressure falls to 50% of its maximum value; when it is > 440 msec, the aortic insufficiency is generally not severe. In our opinion, only rarely are there indications to alter the management of patients with bacterial endocarditis on the basis of the size of the vegetation. Lutas and colleagues at Cornell reported a large prospective study involving patients with bacterial endocarditis, documented clinically, and confirmed by blood cultures. They divided their patients into two majorgroups, those with vegetations and those without vegetations by two-dimensional echocardiography. The incidence of systemic or pulmonary embolization and congestive heart failure was similar among the two groups. When they examined the effect of
40
Figure 2. Parasternal long-axis view from a patient with aortic valve endocarditis. The left ventricle (LV) is dilated and the arrowpoints to a vegetation on the left ventricular outflow tract side of the aortic valve.
the size of the vegetationson clinical events, there was no relationship between the incidence of embolic phenomena, heart failure, or valve dysfunction based on the vegetation size. However, the presence of acute mitral regurgitation due to ruptured chordae and flail mitral valve leaflets and early mitral valve closure due to acute severe aortic regurgitation were both indications for urgent valve replacement. It is especially important not to overreact to the size of tricuspid valve vegetations, which may be enormous (Fig. 4). Patients with even huge tricuspid vegetations may be cured successfully with medical therapy alone. One lesson that echocardiographers have learned is that when vegetations are present on one valve, very careful scrutiny should be undertaken to exclude clinically unsuspected vegetations on other valves and to detect complications of endocarditis such as myocardial abscesses. This is especially important in intravenous drug abusers with vegetative endocarditis involving the valves on the left side of the heart. Careful inspection may reveal multivalve infection. In Figure 5, the echocardiogram of an intravenous drug abuser demonstrates an aortic vegetation prolapsing into the left ventricular outflow tract in diastole. In addition, a large mitral valve vegetation is also seen.
Journal of Cardiac Surgery
Vol. 5,
No. 1, 1990
ECHOCARDIOGRAPHY AND INFECTIVE ENDOCARDITIS
Figure 3. Continuous-wave Doppler pattern from a patient with aortic insufficiency (AR). From the slope of the signal, a rough estimate of aortic insufficiency severity can be made. The signal below the line is mitral regurgitation. Each vertical line corresponds to 7 m/sec.
Until recently, echocardiography has been disappointing in detecting vegetations in patients with prosthetic heart valves. This is most problematic with mechanical valves because the ultrasound beam is almost completely reflected by the metal or pyrrolite components of the prosthesis. Transesophageal echocardiography provides important diagnostic information in many patients, especially those with prosthetic valves. The reason that transesophageal echocardiography images are so much better than transthoracic echocardiography is that the ultrasound beam from the esophagus does not traverse the lungs and therefore is not attenuated by air interfaces. Therefore, higher quality twodimensional echocardiographic images and Doppler velocity signals can be obtained from the esophagus directly through the left atrium (Fig. 6). Figure 7 is a transesophageal echocardiogram taken from a patient with a fever several months following an aortic valve replacement with a
Vol. 5, No. 1, 1990
porcine prosthesis. Because the esophagus is posterior to the heart, the first chamber seen was the left atrium. The porcine prosthesis was well visualized and the leaflets appeared normal. However, a large abscess cavity had developed (A), destroying almost one-third of the annulus and leading to perivalvular aortic insufficiency. None of these findings were appreciated from the standard transthoracic echocardiogram. One of the reasons that transesophageal echocardiography was developed initially was to help surgeons evaluate left ventricular function in the operating room. In the past, intraoperative assessment of left and right ventricular function was at best rudimentary and consisted either of palpation or inspection of the various cardiac chambers or measurement of the changing hemodynamics and cardiac outputs. Furthermore, assessment of valve function was more dependent on the surgeon’s experience than on the available technology. Transesophageal
Journal of Cardiac Surgery
41
SUTTON
Figure 4. Parasternal right ventricular (RV) inflow view from a patient with tricuspid endocarditis. The arrow points to a huge tricuspid vegetation prolapsing into the right atrium in systole.
echocardiography allows reproducible evaluation of left ventricular function, detection of new segmental wall-motion abnormalities resulting from regional ischemia intraoperatively, and recognition of air trapped in the left heart chambers prior to discontinuing cardiopulmonary bypass. Transesophageal echocardiography is extremely useful diagnostically for detection of small vegetations, even those around 1 mm in size. In addition, the anesthetist using transesophageal echocardiography can base strategic pharmacological interventions on realtime left ventricular images. The correction of complex congenital heart disease can also now be evaluated in the operating room. In summary, both transthoracic and transesophageal echocardiography can rmke the diagnosis of bacterial endocarditis. However, ultrasound techniques can also be usedto assess valve dysfunction, the presenceof complications, and success of management of these patients both intraoperatively and at long-term follow-up.
Figure 5. Apical four-chamber view from a patient with multivalvular endocarditis. An aortic vegetation (veg) can be seen in the left ventricle. The other arrow points to a mitral valve vegetation. RV = right ventricle; RA = right atrium.
42
Journal of Cardiac Surgery
Vol. 5, No. 1, 1990
ECHOCARDIOGRAPHY AND INFECTIVE ENDOCARDITIS
Figure 6. Normal transesophageal echocardiogram, long-axis view. The left atrium (LA) is seen at the top because the esophagus lies against the left atrium. The mitral valve leaflets are closed and the detail of the normal aortic valve is seen easily (arrows). LV = left ventricle.
Vol. 5 , No. 1, 1990
Figure 7. Transesophageal echocardiogram from a patient with infection of the aortic valve annulus following valve replacement with a porcine prosthesis. The bioprosthesis is well visualized (P). An abscess cavity (A) next to the prosthesis is seen. These findings were not appreciated by transthoracic echocardiography.
Journal of Cardiac Surgery
43
Diagnosis and Medical Management of Infective Endocarditis: Transthoracic and Transesophageal Echocardiography MARTIN ST. JOHN SUTTON, M.R.C.P. AND RICHARD T. LEE, M.D.
Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
ABSTRACT The use of echocardiography in the diagnosis of vegetative endocarditis has been a keystone in the diagnosis and treatment of this important clinical syndrome. In addition, with the use of transesophageal echo this modality has now made important advances in not only diagnosis but in evaluation of global cardiac function. A considerable amount of information has been gathered on the vegetation and these data will be discussed.
In the early days of echocardiography, ultrasound was very helpful in making the diagnosis of vegetative endocarditis, but there have been many major technological advances since then. One of the questions that the surgeons are asking and that we ask ourselves as echocardiographers is not simply establishing the diagnosis, but ,how to assess the severity of the valvular lesions hemodynamically. In addition, we want to know how to evaluate the lesion through longterm follow-up and how ultrasound information can be used to ensure that patients are in an optimal hemodynamic state prior to surgery. Figure 1 is a two-dimensional echocardiogram from a young man with a history of intravenous drug abuse. A typical mass of vegetations is apparent on the mitral valve, prolapsing into the left atrium. This appearance is classic for mitral Presented at the Workshop on Surgery of Native and Prosthetic Valve Endocarditis. Boston, Massachusetts, May 6, 1989. Sponsored by the German Heart Center, Berlin, West Germany. Address for correspondence: Richard T. Lee, M.D., Director, Echocardiography Laboratory, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 021 15.
Vol. 5, No. 1, 1990
valve endocarditis. A simple way of assessing the severity of regurgitant valve lesions is by Doppler flow mapping. In mitral regurgitation, this entails delineating the area within the left atrium where the high velocity regurgitant jet can be detected. Doppler flow mapping can be performed with pulsed-wave Doppler or more easily with color flow Doppler. Color flow Doppler echocardiography demonstrated a large regurgitant jet of blood in the left atrium during systole in this patient. While the size of a color Doppler jet only roughly corresponds to the volume of regurgitation, it was apparent that the patient in Figure 1 had severe regurgitation that eventually required surgery. . Doppler ultrasound also provides hemodynamic information. The velocity of blood flow (V) is quadratically related to pressure (P). This is defined by the modified Bernoulli equation, in which the pressure gradient P = 4 (VXV). The type of hemodynamic information that can be derived from Doppler is illustrated by the patient in Figure 2. A large mass can be seen on the aortic valve, prolapsing into the left ventricular outflow tract. In Figure 3, the continuous-wave Doppler recording from this patient is shown. A high
Journal of Cardiac Surgery
39
SUTTON
Figure 1. Parasternal long-axis view from a patient with mitral valve endocarditis. The arrow points to a large vegetation prolapsing into the left atrium during systole.
velocity holo-diastolic signal of aortic insufficiency is seen. The instantaneous velocity of the regurgitant blood correlates with the magnitude of the pressure gradient throughout diastole. The difference between the aortic diastolic pressure and left ventricular diastolic pressure can be determined by using the modified Bernoulli equation. When aortic diastolic pressure is low and there is significant elevation of left ventricular end-diastolic pressure, the velocity at end-diastole is small. The slope of the velocity signal or the rate of velocity decay can be used to measure the pressure half-time. The pressure half-time is the time interval during which the pressure falls to 50% of its maximum value; when it is > 440 msec, the aortic insufficiency is generally not severe. In our opinion, only rarely are there indications to alter the management of patients with bacterial endocarditis on the basis of the size of the vegetation. Lutas and colleagues at Cornell reported a large prospective study involving patients with bacterial endocarditis, documented clinically, and confirmed by blood cultures. They divided their patients into two majorgroups, those with vegetations and those without vegetations by two-dimensional echocardiography. The incidence of systemic or pulmonary embolization and congestive heart failure was similar among the two groups. When they examined the effect of
40
Figure 2. Parasternal long-axis view from a patient with aortic valve endocarditis. The left ventricle (LV) is dilated and the arrowpoints to a vegetation on the left ventricular outflow tract side of the aortic valve.
the size of the vegetationson clinical events, there was no relationship between the incidence of embolic phenomena, heart failure, or valve dysfunction based on the vegetation size. However, the presence of acute mitral regurgitation due to ruptured chordae and flail mitral valve leaflets and early mitral valve closure due to acute severe aortic regurgitation were both indications for urgent valve replacement. It is especially important not to overreact to the size of tricuspid valve vegetations, which may be enormous (Fig. 4). Patients with even huge tricuspid vegetations may be cured successfully with medical therapy alone. One lesson that echocardiographers have learned is that when vegetations are present on one valve, very careful scrutiny should be undertaken to exclude clinically unsuspected vegetations on other valves and to detect complications of endocarditis such as myocardial abscesses. This is especially important in intravenous drug abusers with vegetative endocarditis involving the valves on the left side of the heart. Careful inspection may reveal multivalve infection. In Figure 5, the echocardiogram of an intravenous drug abuser demonstrates an aortic vegetation prolapsing into the left ventricular outflow tract in diastole. In addition, a large mitral valve vegetation is also seen.
Journal of Cardiac Surgery
Vol. 5,
No. 1, 1990
ECHOCARDIOGRAPHY AND INFECTIVE ENDOCARDITIS
Figure 3. Continuous-wave Doppler pattern from a patient with aortic insufficiency (AR). From the slope of the signal, a rough estimate of aortic insufficiency severity can be made. The signal below the line is mitral regurgitation. Each vertical line corresponds to 7 m/sec.
Until recently, echocardiography has been disappointing in detecting vegetations in patients with prosthetic heart valves. This is most problematic with mechanical valves because the ultrasound beam is almost completely reflected by the metal or pyrrolite components of the prosthesis. Transesophageal echocardiography provides important diagnostic information in many patients, especially those with prosthetic valves. The reason that transesophageal echocardiography images are so much better than transthoracic echocardiography is that the ultrasound beam from the esophagus does not traverse the lungs and therefore is not attenuated by air interfaces. Therefore, higher quality twodimensional echocardiographic images and Doppler velocity signals can be obtained from the esophagus directly through the left atrium (Fig. 6). Figure 7 is a transesophageal echocardiogram taken from a patient with a fever several months following an aortic valve replacement with a
Vol. 5, No. 1, 1990
porcine prosthesis. Because the esophagus is posterior to the heart, the first chamber seen was the left atrium. The porcine prosthesis was well visualized and the leaflets appeared normal. However, a large abscess cavity had developed (A), destroying almost one-third of the annulus and leading to perivalvular aortic insufficiency. None of these findings were appreciated from the standard transthoracic echocardiogram. One of the reasons that transesophageal echocardiography was developed initially was to help surgeons evaluate left ventricular function in the operating room. In the past, intraoperative assessment of left and right ventricular function was at best rudimentary and consisted either of palpation or inspection of the various cardiac chambers or measurement of the changing hemodynamics and cardiac outputs. Furthermore, assessment of valve function was more dependent on the surgeon’s experience than on the available technology. Transesophageal
Journal of Cardiac Surgery
41
SUTTON
Figure 4. Parasternal right ventricular (RV) inflow view from a patient with tricuspid endocarditis. The arrow points to a huge tricuspid vegetation prolapsing into the right atrium in systole.
echocardiography allows reproducible evaluation of left ventricular function, detection of new segmental wall-motion abnormalities resulting from regional ischemia intraoperatively, and recognition of air trapped in the left heart chambers prior to discontinuing cardiopulmonary bypass. Transesophageal echocardiography is extremely useful diagnostically for detection of small vegetations, even those around 1 mm in size. In addition, the anesthetist using transesophageal echocardiography can base strategic pharmacological interventions on realtime left ventricular images. The correction of complex congenital heart disease can also now be evaluated in the operating room. In summary, both transthoracic and transesophageal echocardiography can rmke the diagnosis of bacterial endocarditis. However, ultrasound techniques can also be usedto assess valve dysfunction, the presenceof complications, and success of management of these patients both intraoperatively and at long-term follow-up.
Figure 5. Apical four-chamber view from a patient with multivalvular endocarditis. An aortic vegetation (veg) can be seen in the left ventricle. The other arrow points to a mitral valve vegetation. RV = right ventricle; RA = right atrium.
42
Journal of Cardiac Surgery
Vol. 5, No. 1, 1990
ECHOCARDIOGRAPHY AND INFECTIVE ENDOCARDITIS
Figure 6. Normal transesophageal echocardiogram, long-axis view. The left atrium (LA) is seen at the top because the esophagus lies against the left atrium. The mitral valve leaflets are closed and the detail of the normal aortic valve is seen easily (arrows). LV = left ventricle.
Vol. 5 , No. 1, 1990
Figure 7. Transesophageal echocardiogram from a patient with infection of the aortic valve annulus following valve replacement with a porcine prosthesis. The bioprosthesis is well visualized (P). An abscess cavity (A) next to the prosthesis is seen. These findings were not appreciated by transthoracic echocardiography.
Journal of Cardiac Surgery
43
