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Hemodynamic Correlates of Echocardiographic Aortic Root Motion
Hemodynamic Correlates of Echocardiographic Aortic Root Motion* Observations on Normal Subjects and Patients with Idiopathic Hypertrophic Subaortic Stenosis Premindra A. N. Chandraratna, M.D.; Weikom Chu, M.D.; Eliot Schechter, M.D.; and Eugene Langevin, D.O.
In ten normal subjects, we observed an initial hump in the aortic root echocardiogram after the onset of the Q R S complex, following which a sharp anterior motion was noted* The onset of the anterior motion of the aortic root coincided with the onset of the upstroke of the aortic root pressure pulse and the onset of the velocity signal in five of seven patients with coronary arterial disease; in the other two, the anterior aortic motion followed the onset of the pressure and velocity signal by 10 msec. The aortic root echocardiogram was abnormal in patients with idiopathic hypertrophic subaortic stenosis; the slope (normalized for the scales of time and
depth) in early systole was steeper and in the latter port of systole was flatter than normal in these patients. The slope in early diastole was flatter and the slope doe to atrial contraction was steeper in the patients with idiopathic hypertrophic subaortic stenosis than in the normal subjects. These features were consistent with rapid ejection in early systole and slow filling in the early phase of ventricular diastole in idiopathic hypertrophic subaortic stenosis. Fourier analysis of the wave form of the aortic root allowed separation between patients with idiopathic hypertrophic subaortic stenosis and normal subjects.
ramiak and Shah1 described the echocardio^ graphic features of the normal and diseased aortic valve. Subsequent investigators have outlined the ultrasonic characteristics of various forms of aortic valvular disease.2"5 Strunk and associates6 described the pattern of motion of the posterior wall of the aortic root and found a good correlation between posterior aortic root motion and the left atrial angiographic area. Our report describes the morphologic features of normal motion of the aortic root, with special emphasis on the hemodynamic correlates in systole. The motion of the aortic root in normal subjects was strikingly different from that seen in patients with idiopathic hypertrophic subaortic stenosis.
transducer with a 10-cm focus, and a strip-chart recorder ( Honeywell 1856) were used. The examination was performed from the interspace from which the mitral valve could be visualized by perpendicular or nearly perpendicular placement of the transducer. The aortic root echocardiogram was obtained by superior and medial angulation of the transducer. I n order to standardize the echocardiographic examination, two cusps of the aortic valve were recorded when obtaining the aortic root echocardiogram. A blowup of the aortic root and aortic valve was then recorded at a paper speed of 50 mm/sec.
MATERIALS AND METHODS Normal Subjects Echocardiograms of the aortic root, electrocardiograms, and phonocardiograms were simultaneously obtained in ten normal subjects ( range of ages, 27 to 47 years ). A n ultrasonoscope (Ekoline 20 Ultrasonoscope), a 2.25-MHz 0.5-inch •From the Division of Cardiology, University of Oklahoma Health Sciences Center, Oklahoma City. Supported by N I H grant 5TO1HL05406. Manuscript received December 19; revision accepted March 21. Reprint requests: Dr. Chandraratna, VA Hospital, Long Beach, California 90822
CHEST, 74: 2, AUGUST, 1978
Coronary Arterial Disease To help clarify the timing of events i n the aortic root, seven patients with coronary arterial disease had studies performed at the time of cardiac catheterization. Aortic root echocardiograms, ECGs, and tracings of ascending aortic pressures were simultaneously obtained by a catheter-tip micromanometer (Millar) and were recorded at paper speeds of 50 and 100mm/sec. Tracings of the velocity of the ascending aortic flow ( obtained by a catheter-tip electromagnetic probe measuring flow), aortic root echocardiograms, and ECGs were also simultaneously recorded at paper speeds of 50 and 100 mm/sec. Idiopathic Hypertrophic
Subaortic Stenosis
Ten consecutive patients (range of ages, 30 to 52 years) who had asymmetric septal hypertrophy (ratio of septal thickness to thickness of posterior wall greater than 1.5) and marked systolic anterior motion of the mitral valve with mitral septal apposition during systole had echocardiograms
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 183
FIGURE 1. Simultaneous recordings of phonocardiogram, ECG, carotid pulse tracing ( C A ) , and aortic root echocardiogram. Following Ρ wave of ECG, there is posterior motion of aortic root ( beginning at point A and ending at V ) ( nomen clature of Strunk et a l ) . This is followed by hump, after which sharp anterior motion (be ginning at Β) is seen. Dip i n aortic root (point C) corresponds to aortic component of second heart sound (S2). Point O represents peak of anterior motion, following which sharp posterior motion (ending in R) is noted. After point R, flat segment (ending in A ) is evident S2, Second heart sound; AwAo, anterior wall of aortic root; PwAo, posterior wall of aortic root; and A V = aortic valve. e
of the aortic root, ECGs, and phonocardiograms (eight pa tients) simultaneously recorded at a paper speed of 50 mm/sec. No patient was receiving cardiac medications at the time of the study. Methods Several cycles of echocardiograms of the posterior wall of the aortic root were traced by hand from the strip chart These tracings were then enlarged onto graph paper. Coordi nates of these wave forms were read off at 61 equally spaced locations and were analyzed on a computer ( I B M 370/158). During the read-off process, the wave forms were normalized both in the scale of time and the scale of depth. This procedure of normalization was performed during the com puterized analysis and consisted of adjusting both the scale of time and the scale of depth so that all wave forms had numerically the same maximum depth and duration. The
amplitude of each aortic root wave form was divided into 100 divisions, with the lowest point being zero and the highest point being 100. The duration of each wave form was divided into 61 divisions, with the beginning of the wave form being time zero and the end of the wave form being time 61. This reduces the variation within the set (caused by different heart rates and different amplitudes), while still preserving the essential configuration of the wave forms. RESULTS
After an initial hump following the QRS complex, the aortic root moved anteriorly (Fig 1 ) . The an terior motion of the aortic root consisted of an initial rapid slope (slope 1, which was the slope of the first quarter of the systolic segment), followed by a less steep slope (slope 2, which was the slope of the
ι EKG
FIGURE 2. A (left), Schematic diagram of normal posterior wall of aortic root, illustrating slopes that were measured. Slope 1 ( S L i ) and slope 2 (SL2) are i n systole, whereas slope 3 (SL3) is in early diastole, and slope 4 ( SL4 ) is result of atrial contraction. Vertical height of OR seg ment (see Fig 1) is X, and that of AV segment is Υ. Β (right), Schematic diagram of posterior aortic wall i n idiopathic hypertrophic subaortic stenosis.
184
CHANDRARATNA ET AL
CHEST, 74: 2, AUGUST, 1978
i 1111 : ; ft * il I í u í ι * Π If
pulse by 10 msec (Fig 3). The dicrotic notch of the pressure pulse coincided with the dip on the aortic root echocardiogram in each instance. The onset of the velocity signal in the aortic root ( measured by a catheter-tip electromagnetic probe measuring velocity) occurred at the same time as the start of the anterior motion of the aortic root echo (Fig 4) in five patients with coronary arterial disease. In two others, the anterior aortic motion followed onset of the velocity signal by 10 msec. Idiopathic
Hypertrophic
Subaortic
Stenosis
The pattern of motion of the aortic root in patients with idiopathic hypertrophic subaortic stenosis was clearly different from that seen in normal subjects. To quantitatively describe these morphologic differ ences, several slopes (shown in Fig 2) were calcu lated by fitting (via method of least squares) a line to each section of interest The results are shown in Table 1. The initial systolic slope of the aortic root (Fig 2 and slope 1) was steeper than normal in patients with idiopathic hypertrophic subaortic stenosis. I n contrast, slope 2 was considerably flatter i
I
Π
Ί
I
!
i
I
FIGURE 3. Simultaneous recordings of ECG, aortic root pres sure (AP; measured by catheter-tip micromanometer), and echocardiogram of posterior wall (Ao) of aortic root. Note that following initial hump, there is sharp anterior motion of aortic root, onset of which corresponds to initial rise of aortic pressure. Dicrotic notch of pressure pulse corresponds to posterior dip in aortic root echocardiogram. Slight further anterior movement of aortic root is seen after end of systole.
second half of the systolic segment; Fig 2). A dip which coincided with the first high-frequency tran sient of the aortic component of the second heart sound was noted on each tracing shortly before maximum anterior displacement (zero point) of the aortic root. Slight anterior motion of the aorta was noted after the dip, following which a sharp pos terior motion (OR segment) followed by a flat or slightly anteriorly moving segment (RA segment) was observed.6 Atrial contraction produced a fur ther sharp posterior motion ( AV segment ). Coronary Arterial
Disease
The onset of anterior motion of the aortic root in systole coincided with the onset of the rise of the pressure in the ascending aorta (measured by a catheter-tip micromanometer) in five patients with coronary disease; and in two others, the anterior aortic motion followed the onset of the pressure CHEST, 74: 2, AUGUST, 1978
FIGURE 4. Simultaneous recordings of ECG, uncalibrated aortic root velocity signal ( V ; recorded with catheter-tip electromagnetic probe measuring velocity), and echocardio gram of posterior wall of aortic root ( Ao). Note that following initial hump, there is anterior motion of aortic root, onset of which coincides with initial blood flow i n ascending aorta.
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 185
T a b l e 1L—Data from Normal Subject* and Patients with Idiopathic Hypertrophic Subaortic Stenosis (IHSS)
Group and Subject Normal 1 2 3 4 5 β 7 8 9 10 IHSS 11 12 13 14 15 16 17 18 19 20 Ρ value**
*
Slope 1
Slope 2
Slope 3
Slope 4
X
Y
Ratio of X / Y
4.525 4.179 6.491 5.648 6.118 5.830 6.403 6.577 6.417 7.199
5.435 3.390 2.820 3.876 4.276 4.619 4.211 3.571 3.081 3.310
-9.859 -6.946 -6.928 -5.999 -7.412 -5.455 -5.420 -5.094 -7.363 -8.032
-3.421 -7.397 -6.266 -4.141 -4.366 -2.835 -4.901 -5.004 -4.840 -4.344
66.557 61.157 61.053 52.778 56.832 43.542 55.556 48.518 68.224 62.057
25.246 27.273 34.737 19.907 20.186 25.461 32.164 46.092 30.530 33.333
2.636" 2.242 1.758 2.651 2.815 1.710 1.727 1.053 2.235 1.862
7.926 7.698 8.792 11.095 7.947 7.802 7.133 15.294 8.576 7.507
0.199 2.138 0.416 -0.283 0.491 -0.052 1.602 0.668 -0.459 0.305
-0.098 -1.529 -0.161 -3.029 -3.474 -2.404 -1.680 -0.523 -1.124 -1.887
-9.690 -5.855 -9.015 -5.266 -5.141 -5.459 -6.887 -11.274 -5.606 -4.475
1.075 19.745 2.976 39.416 31.788 29.949 17.483 15.686 7.407 20.370
80.645 73.248 77.381 31.387 52.318 54.822 60.140 66.667 77.160 37.037
0.013 0.270 0.038 1.256 0.608 0.546 0.291 0.235 0.096 0.550
P<0.005
P<0.01
P<0.005
P<0.005
P<0.005
P<0.005
P<0.005
*Slopes 1 to 4 and X and Y are same as for Figure 2. No units are assigned to slopes or X and Y, since all wave forms were normalised. ^Significant difference between normal subjects and patients with IHSS.
in idiopathic hypertrophic subaortic stenosis (Fig 2). The initial diastolic slope of the aortic root (slope 3) was flatter than normal, and a clear-cut flat or slightly anteriorly moving segment (RA seg ment) was not present in most patients with idio pathic hypertrophic subaortic stenosis. A prominent V wave (slope 4), which was steeper than in the normal subjects, was noted in those who had idio pathic hypertrophic subaortic stenosis. The vertical height of the sharp posterior motion ( OR segment; X in Fig 2) was significantly smaller, the height of the "a" wave (Y in Fig 2) was greater, and the ratio of X/Y was smaller in the group with idiopathic hyper trophic subaortic stenosis. Two representative exam ples are shown in Figure 5. To further establish the differences between the aortic root wave forms observed in normal subjects end in patients with idiopathic hypertrophic sub aortic stenosis, a well-established method of analysis of wave forms, Fourier analysis, was applied. This technique has been applied to the analysis of mitral valvular wave forms.7 The results are shown in Fig ure β. The average amplitudes (normalized for scales of time and depth) of the aortic root were higher for patients with idiopathic hypertrophic subaortic stenosis. Normal subjects tended to have higher amplitudes for their first cosine component but lower amplitudes for their sine component than 186
CHANDRARATNA ET AL
patients with idiopathic hypertrophic subaortic stenosis. All of these differences are statistically sig nificant (P < 0.005). DISCUSSION
Following an initial hump after the onset of the QRS complex, a sharp anterior motion of the aortic root was seen, the onset of which coincided with the initial rise of pressure in the aorta and with the upstroke of the tracing of aortic flow infivepatients; and in two others, a 10-msec lag was noted. The anterior motion had two components, an initial rapid motion followed by a less steep movement. A dip on the aortic root echocardiogram coincided with the onset of the aortic component of the second heart sound and the dicrotic notch of the aortic root pressure pulse, and therefore the dip represented the end of systole. Thus, the onset and end of left ven tricular ejection were definable on the aortic root echocardiogram. The pattern of aortic root motion was strikingly abnormal in patients with idiopathic hypertrophic subaortic stenosis. These patients had an initial an terior motion of the aorta that was steeper than normal, followed by a flat segment which demon strated little or no anterior motion. This pattern of motion is consistent with the characteristic abnor mality of left ventricular ejection that has been de CHEST, 74: 2, AUGUST, 1978
FIGURE 5. Aortic root echocardiograms i n two patients with idiopathic hypertrophic subaortic stenosis. Note steep initial anterior motion of aortic root (slope 1 i n Fig 2 ) , which begins at point B. Left panel shows sharp decrease in slope of aortic root (slope 2 i n Fig 2 ) , which begins at point corresponding to notch of aortic valve (vertical dotted line). Aortic valvular closure (left panel) and second heart sound (S ; right panel), which denote end of systole, occur at point C. I n left panel, there is no further anterior motion after point C; and, therefore, point C and point O (see Fig 1) are coincident. Early diastolic posterior motion (slope 3 ) is reduced, and prominent "a" wave ( slope 4 ) is seen. AWAo, Anterior wall of aortic root; AV, A V segment; PWAo, posterior wall of aortic root; and Si, first heart sound. 2
scribed in idiopathic hypertrophic subaortic stenosis.8 Normal subjects eject about 50 to 55 per80
cent of the stroke volume during the first half of systole. I n contrast, in patients with idiopathic hy80 • Normal
• Normal o IHSS
60
ι
60
o
50
S
50
o ÜJ o
40
5 α. <
30 20 10
o IKSS
70-
70
•
I
40 O UJ O
t
30
<
20 10 -
100 80 90 50 60 70 80 90 100 60 70 50 AVERAGE AMPLITUDE OF ENTIRE WAVEFORM AVERAGE AMPLITUDE OF ENTIRE WAVEFORM FIGURE 6. Scattergram of data from normal subjects and patients with idiopathic hypertrophic subaortic stenosis, based on features generated by Fourier's analysis of aortic root wave forms. A (left), Average amplitude of entire wave form is higher in group with idiopathic hypertrophic subaortic stenosis (IHSS). Normal subjects tend to have lower amplitudes for their first sine component Β (right), Amplitude of first cosine wave tends to be higher i n normal subjects.
CHEST, 74: 2, AUGUST, 1978
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 187
pertrophic subaortic stenosis, flow in the latter half of systole is markedly attenuated, so that 80 to 85 percent of the stroke volume is ejected during the first half of systole.9 I t is likely that the steep initial anterior motion of the aortic root echo corresponds to rapid ventricular ejection, and the relatively flat segment that follows is due to a decrease in aortic flow caused by obstruction of the left ventricular outflow tract. The observation that the systolic notch on the aortic valve corresponded to the end of the steep initial anterior motion of the aortic root (Fig 5) further supports our contention. A striking abnormality in the pattern of diastolic motion of the aortic root was also noted in patients with idiopathic hypertrophic subaortic stenosis. Strunk and his associates6 described the motion of the posterior aortic wall echocardiogram. After opening of the mitral valve, the posterior aortic wall exhibited rapid posterior motion (OR segment). This was followed by a flat or slight anterior move ment (RA segment); and following the Ρ wave of the ECG, an abrupt posterior motion of the aortic wall (AV segment) was observed. Strunk et al 6 correlated these changes with alterations in the left atrial area. In idiopathic hypertrophic subaortic stenosis, the early diastolic slope was reduced. This is consistent with a reduced rate of ventricular filling because of decreased left ventricular compliance. A clear-cut flat or slightly anteriorly moving segment ( RA segment) was not present in most patients with idiopathic hypertrophic subaortic stenosis. I t should be noted that tachycardia also ehminates this flat or slightly anteriorly moving segment. None of our patients had tachycardia (heart rate greater than 100 beats per minute) during the study. A prominent "a" wave was noted on the aortic root echocardiogram in all of our patients. I n the majority of normal subjects, the height of the sharp posterior motion (OR segment) was greater than that of the further sharp posterior motion ( AV seg ment), whereas in patients with idiopathic hyper trophic subaortic stenosis, the latter segment ex ceeded the former ( with the exception of one ). Since Strunk et al e observed a good correlation between posterior aortic wall movement and change in the left atrial angiographic area (hence, probably change in left atrial volume), our findings suggest that a greater amount of left ventricular filling oc curred in the group with idiopathic hypertrophic subaortic stenosis during the "a" wave than during the early phase of diastole, whereas in the normal subjects, early diastolic filling was greater than that during atrial contraction. This underscores the im portance of atrial contraction to ventricular filling in 188
CHANDRARATNA ET AL
patients with idiopathic hypertrophic subaortic ste nosis. Our observations suggest that the motion of the aortic root in idiopathic hypertrophic subaortic stenosis is consistent with rapid ejection during early systole and slow ventricular filling in the initial phase of diastole. The sensitivity and specificity of these echocardiographic abnormalities remain to be established. We wish to emphasize the importance of proper angulation of the transducer in obtaining an ade quate study for proper analysis. Both walls of the aortic root and portions of two aortic valvular cusps should be clearly recorded. Improper angulation may distort the tracing and lead to errors in interpretation. Any well-behaved wave form can be easily trans formed into its appropriate representation of Fourier series, which is a superimposition of a set of sinusoidal components having different ampli tudes and different frequencies.9 The morphologic differences of the original wave forms are then re flected upon the different parameters of their Fourier series. The differences between aortic root wave forms of normal subjects and those of patients with idiopathic hypertrophic subaortic stenosis were reflected in the average amplitude of the wave forms and the amplitudes of the first cosine and sine com ponents. The increase in average amplitude in this group with idiopathic hypertrophic subaortic ste nosis could have been due in part to mitral regurgi tation causing greater anterior motion of the aortic root. These data show how a nonquantitative clinical description of an echocardiographic wave form can be quantitated with the help of a technique developed in applied mathematics. A study of the motion of the aortic root may yield useful information regarding the ejection and dia stolic filling of the left ventricle in other forms of heart disease. We are presently exploring the possi bility of using this information as an aid in the evaluation of other cardiac conditions. A C K N O W L E D G M E N T : Ms. Paula Arabie and Mr. Leonard Lusk provided technical assistance. REFERENCES 1 Gramiak R, Shah P M : Echocardiography of the normal and diseased aortic valve. Radiology 96:1-8, 1970 2 Hirschfield DS, Schiller N : Localization of aortic valve vegetations by echocardiography. Circulation 53:280-285, 1976 3 DeMaria A N , King JF, Salel AF, et al: Echography and phonography of acute aortic regurgitation in bacterial endocarditis. Ann Intern Med 82:329-335, 1975 4 Mann T, McLaurin L , Grossman W , et al: Assessing the hemodynamic severity of acute aortic regurgitation due to infective endocarditis. Ν Engl J Med 293:108-113, 1975
CHEST, 74: 2, AUGUST, 1978
5 Nanda NC, Cramiak R, Manning J, et al: Echocardio graphic recognition of the congenital bicuspid aortic valve. Circulation 49:870-875, 1974 β Strunk B L , Fitzgerald JW, Lipton M , et al: The posterior aortic wall echocardiogram: Its relationship to left atrial volume change. Circulation 54:744-750, 1976 7 Chu W K , Chandraratna PAN, Raeside D E , et al: Toward
CHEST, 74: 2, AUGUST, 1978
the automation of echocardiography. Radiology 123:795¬ 797,1977 8 Hernandez RR, Greenfield JC, McCall B W : Pressure-flow studies i n hypertrophic subaortic stenosis. J Clin Invest 43:401-407,1964 9 Hsu HP: Fourier Analysis. New York, Simon and Schuster, 1970
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 189
In ten normal subjects, we observed an initial hump in the aortic root echocardiogram after the onset of the Q R S complex, following which a sharp anterior motion was noted* The onset of the anterior motion of the aortic root coincided with the onset of the upstroke of the aortic root pressure pulse and the onset of the velocity signal in five of seven patients with coronary arterial disease; in the other two, the anterior aortic motion followed the onset of the pressure and velocity signal by 10 msec. The aortic root echocardiogram was abnormal in patients with idiopathic hypertrophic subaortic stenosis; the slope (normalized for the scales of time and
depth) in early systole was steeper and in the latter port of systole was flatter than normal in these patients. The slope in early diastole was flatter and the slope doe to atrial contraction was steeper in the patients with idiopathic hypertrophic subaortic stenosis than in the normal subjects. These features were consistent with rapid ejection in early systole and slow filling in the early phase of ventricular diastole in idiopathic hypertrophic subaortic stenosis. Fourier analysis of the wave form of the aortic root allowed separation between patients with idiopathic hypertrophic subaortic stenosis and normal subjects.
ramiak and Shah1 described the echocardio^ graphic features of the normal and diseased aortic valve. Subsequent investigators have outlined the ultrasonic characteristics of various forms of aortic valvular disease.2"5 Strunk and associates6 described the pattern of motion of the posterior wall of the aortic root and found a good correlation between posterior aortic root motion and the left atrial angiographic area. Our report describes the morphologic features of normal motion of the aortic root, with special emphasis on the hemodynamic correlates in systole. The motion of the aortic root in normal subjects was strikingly different from that seen in patients with idiopathic hypertrophic subaortic stenosis.
transducer with a 10-cm focus, and a strip-chart recorder ( Honeywell 1856) were used. The examination was performed from the interspace from which the mitral valve could be visualized by perpendicular or nearly perpendicular placement of the transducer. The aortic root echocardiogram was obtained by superior and medial angulation of the transducer. I n order to standardize the echocardiographic examination, two cusps of the aortic valve were recorded when obtaining the aortic root echocardiogram. A blowup of the aortic root and aortic valve was then recorded at a paper speed of 50 mm/sec.
MATERIALS AND METHODS Normal Subjects Echocardiograms of the aortic root, electrocardiograms, and phonocardiograms were simultaneously obtained in ten normal subjects ( range of ages, 27 to 47 years ). A n ultrasonoscope (Ekoline 20 Ultrasonoscope), a 2.25-MHz 0.5-inch •From the Division of Cardiology, University of Oklahoma Health Sciences Center, Oklahoma City. Supported by N I H grant 5TO1HL05406. Manuscript received December 19; revision accepted March 21. Reprint requests: Dr. Chandraratna, VA Hospital, Long Beach, California 90822
CHEST, 74: 2, AUGUST, 1978
Coronary Arterial Disease To help clarify the timing of events i n the aortic root, seven patients with coronary arterial disease had studies performed at the time of cardiac catheterization. Aortic root echocardiograms, ECGs, and tracings of ascending aortic pressures were simultaneously obtained by a catheter-tip micromanometer (Millar) and were recorded at paper speeds of 50 and 100mm/sec. Tracings of the velocity of the ascending aortic flow ( obtained by a catheter-tip electromagnetic probe measuring flow), aortic root echocardiograms, and ECGs were also simultaneously recorded at paper speeds of 50 and 100 mm/sec. Idiopathic Hypertrophic
Subaortic Stenosis
Ten consecutive patients (range of ages, 30 to 52 years) who had asymmetric septal hypertrophy (ratio of septal thickness to thickness of posterior wall greater than 1.5) and marked systolic anterior motion of the mitral valve with mitral septal apposition during systole had echocardiograms
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 183
FIGURE 1. Simultaneous recordings of phonocardiogram, ECG, carotid pulse tracing ( C A ) , and aortic root echocardiogram. Following Ρ wave of ECG, there is posterior motion of aortic root ( beginning at point A and ending at V ) ( nomen clature of Strunk et a l ) . This is followed by hump, after which sharp anterior motion (be ginning at Β) is seen. Dip i n aortic root (point C) corresponds to aortic component of second heart sound (S2). Point O represents peak of anterior motion, following which sharp posterior motion (ending in R) is noted. After point R, flat segment (ending in A ) is evident S2, Second heart sound; AwAo, anterior wall of aortic root; PwAo, posterior wall of aortic root; and A V = aortic valve. e
of the aortic root, ECGs, and phonocardiograms (eight pa tients) simultaneously recorded at a paper speed of 50 mm/sec. No patient was receiving cardiac medications at the time of the study. Methods Several cycles of echocardiograms of the posterior wall of the aortic root were traced by hand from the strip chart These tracings were then enlarged onto graph paper. Coordi nates of these wave forms were read off at 61 equally spaced locations and were analyzed on a computer ( I B M 370/158). During the read-off process, the wave forms were normalized both in the scale of time and the scale of depth. This procedure of normalization was performed during the com puterized analysis and consisted of adjusting both the scale of time and the scale of depth so that all wave forms had numerically the same maximum depth and duration. The
amplitude of each aortic root wave form was divided into 100 divisions, with the lowest point being zero and the highest point being 100. The duration of each wave form was divided into 61 divisions, with the beginning of the wave form being time zero and the end of the wave form being time 61. This reduces the variation within the set (caused by different heart rates and different amplitudes), while still preserving the essential configuration of the wave forms. RESULTS
After an initial hump following the QRS complex, the aortic root moved anteriorly (Fig 1 ) . The an terior motion of the aortic root consisted of an initial rapid slope (slope 1, which was the slope of the first quarter of the systolic segment), followed by a less steep slope (slope 2, which was the slope of the
ι EKG
FIGURE 2. A (left), Schematic diagram of normal posterior wall of aortic root, illustrating slopes that were measured. Slope 1 ( S L i ) and slope 2 (SL2) are i n systole, whereas slope 3 (SL3) is in early diastole, and slope 4 ( SL4 ) is result of atrial contraction. Vertical height of OR seg ment (see Fig 1) is X, and that of AV segment is Υ. Β (right), Schematic diagram of posterior aortic wall i n idiopathic hypertrophic subaortic stenosis.
184
CHANDRARATNA ET AL
CHEST, 74: 2, AUGUST, 1978
i 1111 : ; ft * il I í u í ι * Π If
pulse by 10 msec (Fig 3). The dicrotic notch of the pressure pulse coincided with the dip on the aortic root echocardiogram in each instance. The onset of the velocity signal in the aortic root ( measured by a catheter-tip electromagnetic probe measuring velocity) occurred at the same time as the start of the anterior motion of the aortic root echo (Fig 4) in five patients with coronary arterial disease. In two others, the anterior aortic motion followed onset of the velocity signal by 10 msec. Idiopathic
Hypertrophic
Subaortic
Stenosis
The pattern of motion of the aortic root in patients with idiopathic hypertrophic subaortic stenosis was clearly different from that seen in normal subjects. To quantitatively describe these morphologic differ ences, several slopes (shown in Fig 2) were calcu lated by fitting (via method of least squares) a line to each section of interest The results are shown in Table 1. The initial systolic slope of the aortic root (Fig 2 and slope 1) was steeper than normal in patients with idiopathic hypertrophic subaortic stenosis. I n contrast, slope 2 was considerably flatter i
I
Π
Ί
I
!
i
I
FIGURE 3. Simultaneous recordings of ECG, aortic root pres sure (AP; measured by catheter-tip micromanometer), and echocardiogram of posterior wall (Ao) of aortic root. Note that following initial hump, there is sharp anterior motion of aortic root, onset of which corresponds to initial rise of aortic pressure. Dicrotic notch of pressure pulse corresponds to posterior dip in aortic root echocardiogram. Slight further anterior movement of aortic root is seen after end of systole.
second half of the systolic segment; Fig 2). A dip which coincided with the first high-frequency tran sient of the aortic component of the second heart sound was noted on each tracing shortly before maximum anterior displacement (zero point) of the aortic root. Slight anterior motion of the aorta was noted after the dip, following which a sharp pos terior motion (OR segment) followed by a flat or slightly anteriorly moving segment (RA segment) was observed.6 Atrial contraction produced a fur ther sharp posterior motion ( AV segment ). Coronary Arterial
Disease
The onset of anterior motion of the aortic root in systole coincided with the onset of the rise of the pressure in the ascending aorta (measured by a catheter-tip micromanometer) in five patients with coronary disease; and in two others, the anterior aortic motion followed the onset of the pressure CHEST, 74: 2, AUGUST, 1978
FIGURE 4. Simultaneous recordings of ECG, uncalibrated aortic root velocity signal ( V ; recorded with catheter-tip electromagnetic probe measuring velocity), and echocardio gram of posterior wall of aortic root ( Ao). Note that following initial hump, there is anterior motion of aortic root, onset of which coincides with initial blood flow i n ascending aorta.
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 185
T a b l e 1L—Data from Normal Subject* and Patients with Idiopathic Hypertrophic Subaortic Stenosis (IHSS)
Group and Subject Normal 1 2 3 4 5 β 7 8 9 10 IHSS 11 12 13 14 15 16 17 18 19 20 Ρ value**
*
Slope 1
Slope 2
Slope 3
Slope 4
X
Y
Ratio of X / Y
4.525 4.179 6.491 5.648 6.118 5.830 6.403 6.577 6.417 7.199
5.435 3.390 2.820 3.876 4.276 4.619 4.211 3.571 3.081 3.310
-9.859 -6.946 -6.928 -5.999 -7.412 -5.455 -5.420 -5.094 -7.363 -8.032
-3.421 -7.397 -6.266 -4.141 -4.366 -2.835 -4.901 -5.004 -4.840 -4.344
66.557 61.157 61.053 52.778 56.832 43.542 55.556 48.518 68.224 62.057
25.246 27.273 34.737 19.907 20.186 25.461 32.164 46.092 30.530 33.333
2.636" 2.242 1.758 2.651 2.815 1.710 1.727 1.053 2.235 1.862
7.926 7.698 8.792 11.095 7.947 7.802 7.133 15.294 8.576 7.507
0.199 2.138 0.416 -0.283 0.491 -0.052 1.602 0.668 -0.459 0.305
-0.098 -1.529 -0.161 -3.029 -3.474 -2.404 -1.680 -0.523 -1.124 -1.887
-9.690 -5.855 -9.015 -5.266 -5.141 -5.459 -6.887 -11.274 -5.606 -4.475
1.075 19.745 2.976 39.416 31.788 29.949 17.483 15.686 7.407 20.370
80.645 73.248 77.381 31.387 52.318 54.822 60.140 66.667 77.160 37.037
0.013 0.270 0.038 1.256 0.608 0.546 0.291 0.235 0.096 0.550
P<0.005
P<0.01
P<0.005
P<0.005
P<0.005
P<0.005
P<0.005
*Slopes 1 to 4 and X and Y are same as for Figure 2. No units are assigned to slopes or X and Y, since all wave forms were normalised. ^Significant difference between normal subjects and patients with IHSS.
in idiopathic hypertrophic subaortic stenosis (Fig 2). The initial diastolic slope of the aortic root (slope 3) was flatter than normal, and a clear-cut flat or slightly anteriorly moving segment (RA seg ment) was not present in most patients with idio pathic hypertrophic subaortic stenosis. A prominent V wave (slope 4), which was steeper than in the normal subjects, was noted in those who had idio pathic hypertrophic subaortic stenosis. The vertical height of the sharp posterior motion ( OR segment; X in Fig 2) was significantly smaller, the height of the "a" wave (Y in Fig 2) was greater, and the ratio of X/Y was smaller in the group with idiopathic hyper trophic subaortic stenosis. Two representative exam ples are shown in Figure 5. To further establish the differences between the aortic root wave forms observed in normal subjects end in patients with idiopathic hypertrophic sub aortic stenosis, a well-established method of analysis of wave forms, Fourier analysis, was applied. This technique has been applied to the analysis of mitral valvular wave forms.7 The results are shown in Fig ure β. The average amplitudes (normalized for scales of time and depth) of the aortic root were higher for patients with idiopathic hypertrophic subaortic stenosis. Normal subjects tended to have higher amplitudes for their first cosine component but lower amplitudes for their sine component than 186
CHANDRARATNA ET AL
patients with idiopathic hypertrophic subaortic stenosis. All of these differences are statistically sig nificant (P < 0.005). DISCUSSION
Following an initial hump after the onset of the QRS complex, a sharp anterior motion of the aortic root was seen, the onset of which coincided with the initial rise of pressure in the aorta and with the upstroke of the tracing of aortic flow infivepatients; and in two others, a 10-msec lag was noted. The anterior motion had two components, an initial rapid motion followed by a less steep movement. A dip on the aortic root echocardiogram coincided with the onset of the aortic component of the second heart sound and the dicrotic notch of the aortic root pressure pulse, and therefore the dip represented the end of systole. Thus, the onset and end of left ven tricular ejection were definable on the aortic root echocardiogram. The pattern of aortic root motion was strikingly abnormal in patients with idiopathic hypertrophic subaortic stenosis. These patients had an initial an terior motion of the aorta that was steeper than normal, followed by a flat segment which demon strated little or no anterior motion. This pattern of motion is consistent with the characteristic abnor mality of left ventricular ejection that has been de CHEST, 74: 2, AUGUST, 1978
FIGURE 5. Aortic root echocardiograms i n two patients with idiopathic hypertrophic subaortic stenosis. Note steep initial anterior motion of aortic root (slope 1 i n Fig 2 ) , which begins at point B. Left panel shows sharp decrease in slope of aortic root (slope 2 i n Fig 2 ) , which begins at point corresponding to notch of aortic valve (vertical dotted line). Aortic valvular closure (left panel) and second heart sound (S ; right panel), which denote end of systole, occur at point C. I n left panel, there is no further anterior motion after point C; and, therefore, point C and point O (see Fig 1) are coincident. Early diastolic posterior motion (slope 3 ) is reduced, and prominent "a" wave ( slope 4 ) is seen. AWAo, Anterior wall of aortic root; AV, A V segment; PWAo, posterior wall of aortic root; and Si, first heart sound. 2
scribed in idiopathic hypertrophic subaortic stenosis.8 Normal subjects eject about 50 to 55 per80
cent of the stroke volume during the first half of systole. I n contrast, in patients with idiopathic hy80 • Normal
• Normal o IHSS
60
ι
60
o
50
S
50
o ÜJ o
40
5 α. <
30 20 10
o IKSS
70-
70
•
I
40 O UJ O
t
30
<
20 10 -
100 80 90 50 60 70 80 90 100 60 70 50 AVERAGE AMPLITUDE OF ENTIRE WAVEFORM AVERAGE AMPLITUDE OF ENTIRE WAVEFORM FIGURE 6. Scattergram of data from normal subjects and patients with idiopathic hypertrophic subaortic stenosis, based on features generated by Fourier's analysis of aortic root wave forms. A (left), Average amplitude of entire wave form is higher in group with idiopathic hypertrophic subaortic stenosis (IHSS). Normal subjects tend to have lower amplitudes for their first sine component Β (right), Amplitude of first cosine wave tends to be higher i n normal subjects.
CHEST, 74: 2, AUGUST, 1978
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 187
pertrophic subaortic stenosis, flow in the latter half of systole is markedly attenuated, so that 80 to 85 percent of the stroke volume is ejected during the first half of systole.9 I t is likely that the steep initial anterior motion of the aortic root echo corresponds to rapid ventricular ejection, and the relatively flat segment that follows is due to a decrease in aortic flow caused by obstruction of the left ventricular outflow tract. The observation that the systolic notch on the aortic valve corresponded to the end of the steep initial anterior motion of the aortic root (Fig 5) further supports our contention. A striking abnormality in the pattern of diastolic motion of the aortic root was also noted in patients with idiopathic hypertrophic subaortic stenosis. Strunk and his associates6 described the motion of the posterior aortic wall echocardiogram. After opening of the mitral valve, the posterior aortic wall exhibited rapid posterior motion (OR segment). This was followed by a flat or slight anterior move ment (RA segment); and following the Ρ wave of the ECG, an abrupt posterior motion of the aortic wall (AV segment) was observed. Strunk et al 6 correlated these changes with alterations in the left atrial area. In idiopathic hypertrophic subaortic stenosis, the early diastolic slope was reduced. This is consistent with a reduced rate of ventricular filling because of decreased left ventricular compliance. A clear-cut flat or slightly anteriorly moving segment ( RA segment) was not present in most patients with idiopathic hypertrophic subaortic stenosis. I t should be noted that tachycardia also ehminates this flat or slightly anteriorly moving segment. None of our patients had tachycardia (heart rate greater than 100 beats per minute) during the study. A prominent "a" wave was noted on the aortic root echocardiogram in all of our patients. I n the majority of normal subjects, the height of the sharp posterior motion (OR segment) was greater than that of the further sharp posterior motion ( AV seg ment), whereas in patients with idiopathic hyper trophic subaortic stenosis, the latter segment ex ceeded the former ( with the exception of one ). Since Strunk et al e observed a good correlation between posterior aortic wall movement and change in the left atrial angiographic area (hence, probably change in left atrial volume), our findings suggest that a greater amount of left ventricular filling oc curred in the group with idiopathic hypertrophic subaortic stenosis during the "a" wave than during the early phase of diastole, whereas in the normal subjects, early diastolic filling was greater than that during atrial contraction. This underscores the im portance of atrial contraction to ventricular filling in 188
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patients with idiopathic hypertrophic subaortic ste nosis. Our observations suggest that the motion of the aortic root in idiopathic hypertrophic subaortic stenosis is consistent with rapid ejection during early systole and slow ventricular filling in the initial phase of diastole. The sensitivity and specificity of these echocardiographic abnormalities remain to be established. We wish to emphasize the importance of proper angulation of the transducer in obtaining an ade quate study for proper analysis. Both walls of the aortic root and portions of two aortic valvular cusps should be clearly recorded. Improper angulation may distort the tracing and lead to errors in interpretation. Any well-behaved wave form can be easily trans formed into its appropriate representation of Fourier series, which is a superimposition of a set of sinusoidal components having different ampli tudes and different frequencies.9 The morphologic differences of the original wave forms are then re flected upon the different parameters of their Fourier series. The differences between aortic root wave forms of normal subjects and those of patients with idiopathic hypertrophic subaortic stenosis were reflected in the average amplitude of the wave forms and the amplitudes of the first cosine and sine com ponents. The increase in average amplitude in this group with idiopathic hypertrophic subaortic ste nosis could have been due in part to mitral regurgi tation causing greater anterior motion of the aortic root. These data show how a nonquantitative clinical description of an echocardiographic wave form can be quantitated with the help of a technique developed in applied mathematics. A study of the motion of the aortic root may yield useful information regarding the ejection and dia stolic filling of the left ventricle in other forms of heart disease. We are presently exploring the possi bility of using this information as an aid in the evaluation of other cardiac conditions. A C K N O W L E D G M E N T : Ms. Paula Arabie and Mr. Leonard Lusk provided technical assistance. REFERENCES 1 Gramiak R, Shah P M : Echocardiography of the normal and diseased aortic valve. Radiology 96:1-8, 1970 2 Hirschfield DS, Schiller N : Localization of aortic valve vegetations by echocardiography. Circulation 53:280-285, 1976 3 DeMaria A N , King JF, Salel AF, et al: Echography and phonography of acute aortic regurgitation in bacterial endocarditis. Ann Intern Med 82:329-335, 1975 4 Mann T, McLaurin L , Grossman W , et al: Assessing the hemodynamic severity of acute aortic regurgitation due to infective endocarditis. Ν Engl J Med 293:108-113, 1975
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5 Nanda NC, Cramiak R, Manning J, et al: Echocardio graphic recognition of the congenital bicuspid aortic valve. Circulation 49:870-875, 1974 β Strunk B L , Fitzgerald JW, Lipton M , et al: The posterior aortic wall echocardiogram: Its relationship to left atrial volume change. Circulation 54:744-750, 1976 7 Chu W K , Chandraratna PAN, Raeside D E , et al: Toward
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the automation of echocardiography. Radiology 123:795¬ 797,1977 8 Hernandez RR, Greenfield JC, McCall B W : Pressure-flow studies i n hypertrophic subaortic stenosis. J Clin Invest 43:401-407,1964 9 Hsu HP: Fourier Analysis. New York, Simon and Schuster, 1970
ECHOCARDIOGRAPHIC AORTIC ROOT MOTION 189