Effect of depressed left ventricular function on hemodynamics of normal St. Jude medical prosthesis in the aortic valve position

VALVULAR

HEART DISEASE

Effect of Depressed Left Ventricular Function on Hemodynamics of Normal St. Jude Medical Prosthesis in the Aortic Valve Position Jian-Fang Ren, MD, Krishnaswany Chandrasekaran, MD, Gary S. Mintz, MD, John Ross, RCPT, Ronald S. Pennock, MD, and William S. Frankl, MD

To evaluate the effect of lefl ventricular (LV) dysfunction on Doppler-derived transprosthetic hemodynamic indexes in patients with normally functioning St. Jude aortfc valve prostheses, 74 consecutive patients were studied. LV ejection fraction was assessed by using Simpson’s biplane rule. The 34 patients with normal ejection fraction (20.51) (group A) generally had the highest values of peak (31 f 13 mm Hg) and mean (16 f 6 mm Hg) gradlents, whereas 19 patients with moderate to severe reduction of ejection fraction (sO.31) (group C) had the lowest values (17 f 6 and 9 f 3 mm Hg, respectively) (p
From the Likoff Cardiovascular Institute, Hahnemann University, Pniladelphia, Pennsylvania. Manuscript received August 11, 1989; revised manuscript received December 11,1989, and accepted December 13. Address for reprints: Jian-Fang Ren, MD, Cardiac Ultrasound Laboratory, Hahnemann University Hospital, 230 North Broad Street, Mail Stop 3 13, Philadelphia, Pennsylvania 19102.

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linical and hemodynamic advantages of the St. Jude cardiac valve prosthesis have been demonstrated by angiographic,‘-3 noninvasive and Doppler echocardiographic studies.4,5 Evaluation of prosthetic valvular dysfunction has been a difficult problem. Quantitative Doppler echocardiography has been used for detecting flow characteristics and pressure gradients in patients with normal prosthetic valves.6 Before prosthetic valve dysfunction can be diagnosed, the range and variation of a normal Doppler study must be defined. However, many patients undergoing aortic valve replacement for aortic stenosis or re gurgitation already have reduced left ventricular (LV) function. This study was designed to evaluate the effect of LV dysfunction on Doppler-derived hemodynamic indexes in patients with a normally functioning St. Jude aortic valve prosthesis.

C

METHODS

Study patients: Patients were deemed to have normal aortic valve prostheses if they had no clinical suspicion of prosthetic dysfunction and no prosthesis-related complication based on history, physical examination and follow-up postoperative Doppler echocardiographic study as previously described in our laboratory.4,5 These prostheses were not proven normal by catheterization because such invasive study is no longer warranted. Between September 1984 and October 1988, 74 consecutive asymptomatic patients with a clinically normal functioning St. Jude aortic valve prosthesis had routine baseline and follow-up high quality cardiac images and Doppler flow studies (Table I). There were 43 men and 31 women with a mean age of 61 years (range 15 to 91). The postoperative interval was 2.1 f 2.1 years (range 1 week to 6 years). None was clinically suspected of having prosthetic dysfunction, Patients receiving @-blocking medication were excluded from this study. Doppler echocardiography: Doppler echocardiographic studies were performed with Irex Meridian phased array or Interspec XL mechanical ultrasound system with pulsed and continuous mode Doppler ultrasound. LV ejection fraction was derived from end-diastolic and end-systolic volumes determined by tracings from 2 apical orthogonal views and using Simpson’s biplane rule.’ The peak flow velocity spectral signals across the aortic valve prosthesis were recorded from apical, right parastemal or suprastemal approaches. Peak velocity was the highest value recorded from multiple views. Peak pressure gradient (Ap) was estimated

from the peak transvalvular velocity (V) using the modified Bernoulli equation (Ap = 4V”). The mean velocity and mean pressure gradient, corrected time of flow (dividing by -\/RR to correct for heart rate) and peak acceleration were calculated using commercially available hardware and software from the videotape. Corrected velocity time integral was calculated by multiplying the mean velocity and corrected time of flow. For all patients, 3 to 5 cardiac cycles were measured and averaged. In 6 patients with arrhythmia, L5 cardiac cycles were measured. Aortic and mitral regurgitation was detected semiquantitatively using the mapping technique with rangegated pulse Doppler as previously describeds5 Subjective evaluation of LV wall motion abnormalities was assessed by independent observers without knowledge of the quantitative data. Statistical analysis: Results are expressed as mean f standard deviation. Statistical correlation between Doppler-derived measurements and prosthetic size was made using linear regression analysis. Statistically significant differences between means of different groups were determined using the unpaired t test or analysis of variance as appropriate. A p value of 10.05 was considered significant and that of
Postoperative characteristics and general echocardiographic findings are listed in Table I. Mild aortic regurgitation was found in 14 (19%) patients and LV segmental wall motion abnormalities in 27 (36%) patients. According to the 2-dimensional echocardiographic quantitative determination of LV ejection fraction, the patients were divided into 3 groups. Group A included 34 patients with normal LV ejection fraction (20.51)8; group B included 21 patients with mild to moderate reduction of LV ejection fraction (0.50 to 0.32); group C included 19 patients with moderate to severe reduction of LV ejection fraction (10.31). Table II lists Dopplerderived hemodynamic measurements of these 3 groups with different prosthetic sizes. Means of the peak (3 1 f 13 mm Hg) and mean (16 f 6 mm Hg) pressure gradients ranged from 12 to 77 and 6 to 30 mm Hg, respectively. The group A patients with normal LV function generally had the highest values of gradients compared to the group B and C patients with LV dysfunction, especially at given smaller valve sizes (19, 21 and 23 mm) rather than larger sizes (25, 27 and 29 mm). Means of the peak (17 f 6 mm Hg) and mean (9 f 3 mm Hg) pressure gradients of the group C patients with moderate to severe LV dysfunction were the lowest values, ranging from 10 to 36 and 5 to 18 mm Hg, respectively. There were statistically significant decreases for the mean values of the peak and mean pressure gradients and acceleration and corrected velocity time integral measurements for group C compared to groups A and B (p <0.05 to 0.001, Figure 1). Mean pressure gradient and acceleration measurements in group B patients were also significantly reduced com-

TABLE

I Postoperative

Characteristics

of 74 Study

No. (%)

Sex: M/F Postoperatwe

43/31 Interval

(yrs)

Doppler echocardrography LV ejection fraction Group A 20.51

Group

Mean f SD (Range) 61 f 14 (15-91)

Age Ws)

Group

Patients

B 0.50

2.1 f 2.1 (1 week-6 years)

34 (46)

to 0.32

21(28)

C SO.31

19 (26)

Aortic regurgitatron (mild) Mrtral regurgitabon (mild) Segmental LV abnormality LV hypertrophy Pericardial Effusion Atrial fibrillation Mitral valve prosthesis LV = left ventricular:

0.61 f 0.09 (0.514.77) 0.43 f 0.06 (0.324.50) 0.22 f 0.06 (0.10031)

SD = standard

14(19) 4 (5) 27 (36) 12 (16) 5 (7)

6 (8) 6 (8) devmtlon

pared with those in group A (p <0.05 to 0.025, Figure 1). The average prosthetic valve size in each group was 23 mm. A significant inverse correlation (p <0.05) for Doppler-derived peak (r = -0.71) and mean (r = -0.41) gradients, and corrected velocity time integral (r = -0.44) was demonstrated with increasing aortic valve prosthetic size from 19 to 29 mm in group A patients; there was a lesser reduction of such a correlation in group B or C patients (Table III). Figure 2 shows correlation for the peak and mean pressure gradient and corrected velocity time integral with the prosthetic valve size in these 3 groups. Group C patients (ejection fraction 10.31) had the lowest values for any given prosthetic size. Inter- and intraobserver variation: Interobserver variation for quantitative measurement of peak velocity was assessedin 47 patients between 2 independent observers. The interobserver variability for peak velocity was 1.1 f 1.O%. LV ejection fraction was measured by a single observer without knowledge of the Doppler quantitative data. The intraobserver variability for ejection fraction assessedin 30 patients was 9 f 1%. DISCUSSION Depressed left ventricular ejection fractiin in patients with normally functioning St. Jude aortic valve prosthesis: Many of the patients who survive aortic

valve replacement improve their LV function during follow-UP.~ Some patients, however, have a poor outcome. Two-dimensional echocardiographic determination of LV ejection fraction using Simpson’s biplane rule has compared favorably with cineangiographic and radionuelide angiographic measurements’ and has been routinely accepted as a quantitative technique for evaluating LV function.9,‘0 In 74 patients with a normally functioning St. Jude aortic prosthesis in this study, 40 THE AMERICAN

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(54%) had a reduced LV ejection fraction (0.33 f 0.12) <0.5 1 during a mean postoperative period of 2.1 years. LV end-diastolic volume index (I 101 ml/m2) was increased in 60% (44 of 74) of our patients with an abnormal LV ejection fraction. In a recent study, similar abnormalities in LV size and function were demonstrated in 180 patients having aortic valve replacement and postoperative catheterization study.’ l Hwang et al* I reported a postoperative depressed LV function (ejection fraction
on

left ventricular hemodynamic

ing effective flow area, LV function, heart rate and flow period (systolic ejection period).12 The findings in this study confirm that changes in LV function may have an effect on measured pressure gradients, independent of prosthetic valve function. Peak and mean gradients were decreased in patients with reduced LV ejection fraction, especially 10.31, and a normally functioning prosthesis. Statistical difference for such a decrease in these gradient measurements became more significant between the group A and B to group C patients, especially those with smaller (21 and 23 mm) or average prosthetic sizes. Although the patients were not selected to equalize average valve size in each group, the size was similar (23 mm). Doppler-derived pressure gradients may be compared in the presence of stable LV function. Ramirez et al6 studied 107 patients with normal LV ejection fraction determined by %-dimensional echocardiography in 4 different models of aortic valve

ejection fraction measurements:

Doppler-derived pressure gradient across the aortic valve prosthesis is dependent on several factors includ-

Peak 50

-x7

Mean

Group 0 A 0 B ta c

-x7

-3

LVEF 2 0.51 0.50-0.32 I 0.31

x p
E 40 -5

i.- 30 u 2 CJ 20 Q, 5 ; 10 h

FIGURE 1. Comparison of peak and mean w-m grdmt (4 ~a~ (4, and con-e&d velocity the integral (c) betweon group A (left ventricular ejection fraction [LVEF] >O.Sl), group B (LVEF OS0 to 0.32) and group C (LVEF 10.31) patients with an average pro&etii valve sizeof23mm.

A o

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TABLE II Comparison of Doppler-Derived Hemodynamic Depressed Left Ventricular Function at a Given Prosthetic

Measurements Size

PG

Size (mm)

Group

No.

19

A

8

21

B A

1 10

(mm

W

44f 17 (24-77) 31 34f7

9

23

25

B C A

3 7 4

27

0 C A

4 3 4

27f7 23f9 30f6 (23-39) 27f8 16f4 21zk3 (18-25) 25f7 16f5 16f3 (13-19) 23f7 15f2 12 12

4 7

0 C A B

29 Act = acceleration;

HR = heart rate: MG = mean pressure Ranges are gwen in parentheses.

TABLE

Ill Correlation

of Doppler-Derived

PG (mm

gradient;

Hg)

Groups

of Patients

Act.

VTIC

(mm Hg)

(m/s2)

Cm)

PG = peak pressure

Hemodynamic

Three

MG

22zk8 (13-30) 16 17f3 (12-22) 1444 12f4 15f4 (11-21) 13i4 8i2 llf3 (8-15) 13*4 8f4 9*2 (6-11) 12f4 7~~~0.2 7 7

W-46) B C A

Between

84f42 (M-180) 41 105*59 (36-240) 65f28 61i23 79f56 (35-187) 47f16 34f23 58f39 (45-98) 69+15 31f15 73f45 (28-130) 35i30 50424 73 48 gradient; VTlc = corrected

Measurements

with Prosthetic

with Normal

and

HR (beats/min)

0.480f0.185 (0.384-0.912) 0.836 0.424iO.085 (0.36SO.588) 0.411 f 0.090 0.440 f 0.100 0.452 zkO.070 (0.3914560) 0.458f0.050 0.349f0.070 0.374*0.030 (0.338~400) 0.386iO.060 0.341 f 0.043 0.312 f 0.013 (0.3OcO.330) 0.38OiO.060 0.304* 0.050 0.276 0.240

80f14 (62-104) 100 77 f (62-97) 91 f 82f23 70*9 (58-84) 88i18 88+18 83+13 (67-95) 94f14 86 f 81i9 (72-94) 76f5 90-t 74 86

10 21

2.6

10

veloctty tome Integral.

Valve Size from Vk

MG (mm Hg)

19 to 29 mm

(m) I

Group

A

B

C

A

B

C

A

B

C

r Slope Int

-0.71 -3.4 106.2

-0.43 -1.1 52.1 <0.05

-0.46 -1.1 44.7 <0.05

-0.41 -0.7 30.9 <0.05

-0.37 -0.5 24.0
-0.53 -0.7 25.6 <0.05

-0.44 -0.0115 0.702 <0.05

-0.49 -0.022 0.931 <0.05

-0.55 -0.0197 0.826 <0.05

P value


Int = intercept

TABLE

IV

of linear regression

Reported

line; other abbrwattons

Peak Pressure Valve Pts (n)

Study Cooper’” No.

13

Panidiss No. Present study Group A No. 0 No.

33

C No.

34 21 19

as in Table II.

Gradients

(in mm Hg) of St. Jude Aortic

Valve Prosthesis

Size (mm)

19

21

23

25

27

36f7 2 38f20 4

27f8 3 26A7 6

34f7 3 21f12 14

19 f 3 3 20f9 9

16 1

44f17 8 31 1

34f7 10 27f7 9 23f9 4

30f6 7 27f8 3 16f4 7

21f3 4 25f7 4 16f5 3

16f3 4 23i7 3 15f2 5

prostheses and reported the means of maximal velocities by model and size ranging from <2 to 4 m/s. However, in the other previous studies5J2m15patients with normally functioning prostheses may not be distinguished from those with depressed or normal LV function. The findings of this study showed that a depressed LV ejection fraction in patients with a normally functioning prosthesis resulted in corresponding decreases in Doppler-derived transvalvular hemodynamic measurements. Such

29

31 16 1

12 1 12 1

an effect became much more significant when the depressed LV ejection fraction was 10.3 1. Thus, relatively normal measurements of pressure gradients in the presence of depressed LV ejection fraction may not rule out an abnormally functioning prosthetic aortic valve. Relation

of Doppler-derived

hemodynamic

mea-

surements to prosthetk size: Our data further confirm that Doppler-derived peak and mean pressure gradient correlated inversely with increasing prosthetic size from THE AMERICAN

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Group

H

=. BA 0.50-0.32 > 0.51

60

E E 5

LVEF

A c

-----

IO.31

50

*-

40

3

6 2 z 12 i j$

30 20 10

Lt 0

19

A

21 23 25 27 Prosthetic Valve Size (mm)

29

40 F E

FIGURE 2. corddon

for the peak (A) andmeam preuuegr-(B)aml-rected velocity fhe integral (c) with the pmdhetk valve she is dirplayed as so/id

30

2 .3 6

ii#N?fCWglWpA,~iOlIgddk?d/h?fOlgroupBandasshorf&shdhesfor glWpC.lRWlf-lkVktl~Of eacilgralpisintrlcatedatdllprorthetic valve size. Measwwnemt 1patisnthgroupAandBeachbdisplayedassymbel%ean9’atthevaiveslze of 29 mm.

20

L ii 3 h

10

El $

0

6

-19

21 23 25 27 Prosthetic Valve Size (mm)

I 29

0.700 E 0.600

/ 0

I G/J

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19 to 29 mm. Similar results have been reported by others.6.12,13However, correlation between St. Jude aortic valve prosthetic size and the peak and mean gradients significantly improved in this study (r = -0.71 and -0.41, respectively) compared with the data of Cooper et alI2 (r = -0.36 and -0.34) and other previous reports.5,14 In our study, the means and the range of Doppler-derived pressure gradients represented not only the prosthetic size, but also the LV function. Comparing our absolute values of Doppler-derived peak and mean pressure gradient with those previously reported,5,12 we find that peak gradient measurements at a given prosthetic size had a meaningful spread relating to patients’ LV function (Table IV). Generally, peak gradients in our patients with normal LV ejection fraction (group A) were a little higher than usually reported, while those with depressed LV ejection fraction, especially in group C, were lower. Therefore, these results demonstrate that the individual variability in normal values was significantly influenced by such factors as valve size and LV function. Limitations: Although the number of patients with St. Jude aortic valve prostheses was relatively large in this study (especially compared to those previously reported), it was still a small number to be subdivided into multiple groups with different prosthetic size and LV ejection fraction. In order to attain a statistically significant level, combined data in adjacent groups and in an average prosthetic size were necessary. Although the effective prosthetic valve area may be estimated by using the continuity equation, I6 it was not determined in this study due to its retrospective nature. Clinical implications: Depressed LV function resulted in corresponding decreases in Doppler derived transvalvular gradients in patients with normally functioning aortic valve prostheses. In addition to valve size, LV function should be considered as another important factor in detecting prosthetic valvular flow characteristics and dysfunction, especially in patients with depressed LV function and significant valvular stenosis. We greatly appreciate the statistical analysis assistance of He Tong, MD, and the techAcknowledgment:

nical assistance of M. McAllister, RDMS, and R. Foley, RCPT, and extend special thanks to Cathy Coin for help in the preparation of this manuscript.

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Surg

198/;8/:6/5-620. 2. NicoloffDM, Emery RW. Arom KV. Northrup III WF, JorgensenCR. Wang Y. Lindsay WG. Clinical and hemodynamic results with the St. Jude medical cardiac valve prosthesis--a three year experience. J That Cardiouasc Surg

1981,82:674-6X3. 3. Lillehei CW.

Worldwide experience with the St. Jude mitral valve prosthesis: clinical and hemodynamic results. Contemp Surg /982;20:/7-32. 4. Panidis IP, Ren JF, Kotler MN, Mintr GS, Mundth ED, Gael IP. Ross J. Clinical and echocardiographic evaluation of the St. Jude cardiac valve prosthesis: Follow-up of 126 patients. J/ICC 1984;4:454-462. 5. Panidis IP, Ross J. Mintr GS. Normal and abnormal prosthetic valve function as assessed by Doppler echocardiography. JACC 1986;8:3/7-326. 6. Ramirer ML, Wong M, Sadler N, Shah PM. Doppler evaluation of bioprosthetic and mechanical aortic valves: data from four models in I07 stable, ambulatory patients. Am Heart J 1988;1lS:4/8-425. 7. Ren JF. Kotler MN, DePace NL, Mintz GS. lskandrian AS, Hakki A-H, Panidis IP, Kimbiris D, Segal BL. Comparison of left ventricular ejection fraction and volumes by two-dimensional echocardiography, radionuclide angiography. and cineangiography. J Cardioaasc Ultrasonogr 1983;2:213--222. 8. Kennedy JW, Baxley WA, Figley MM, Dodge HT, Blackman JR. Quantitative angiocardiography: the normal left ventricle in man. Circulation

1966:34:272-278. 9. Ren JF, Panidis IP, Kotler MN, syndrome: comparison with chronic

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GS, Gael I, Ross J. Flail mitral valve regurgitation of other etiologies. Am

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289. 11. Hwang

MH, Hammermeister KE, Bousvaros G. Wong M, Sothi GK, Henderson W. Preoperative predictors of depressed left ventricular function after aortic valve replacement (abstr). Circulation 1988;78(suppl 11):11-380. 12. Cooper DM, Stewart WJ, Schiavone WA, Lombard0 HP, Lytle BW, Loop FD. Salcedo EE. Evaluation of normal prosthetic valve function by Doppler echocardiography. Am Heart J 1987:/ 14:576-582. 13. Williams GA, Labovitz AJ. Doppler hemodynamic evaluation of prosthetic (Starr-Edwards and Bjork-Shiley) and bioprosthetic (Hancock and CarpentierEdwards) cardiac valves. Am J Cardiol /985;56:325-332. 14. Mintr GS, Ross J, Panidis IP, Chandrasekaran K. Doppler ultrasound in 366 patients with prosthetic valves: a 4 year experience (abstr). Circuhion

1988:78(.mppl

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15. Verges B, Lafleche A, Malergue MC. ic valve dysfunction. Inf J Card Imaging 16. Chafijadeh Jude’s prosthetic

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ER, Zoghbi WA. improved Doppler aortic valve using the continuity

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