Hemodynamic evaluation of porcine bioprostheses in the mitral position by doppler echocardiography

Hemodynamic Evaluationof PorcineBioprostheses in the Mitral Positionby DopplerEchocardiography MOHAMED EID FAViZY, MRCP, MURTADA HALIM, MRCP, GALAL ZIADY, MD, EDWARD MERCER, MD, ROBERT PHILLIPS, MS, PhD, and WILFRED0 ANDAYA, RCT

Twenty-four patients with porcine biopmstheses in the mitral positton were studied by Doppler echocardkgraphy fottowed by cardiac catheterization within 24 hours. Doppler mean diastolk mitral vatve gradient wes calculated by a 3-point method and mttral valve area was determined by the pressure half-time method. Data from Doppler echocardiography and cardfac catheterization were compared. There was a strong correlation between Do$pler echocardiography and catheterizatii-determined mean diastolic gradient: r = 0.9, standard error of estimate (SEE) = 1.4 mm/Hg (regression equation Y = 0.63x i- 1.41), p
N

oninvasive assessment of porcine bioprosthetic valves has been sought since their introduction 16 years ago. Two-dimensional echocardiography is helpful in detecting some structural changes that occur due to tissue degeneration.1-3 However, it gives only indirect information about the function of these valves. Recent advances in Doppler technology allow both qualitative and quantitative evaluation of stenotic and regurgitant lesions of prosthetic heart valves.4-8 The purpose of this study is to assess the accuracy of Doppler echocardiography in hemodynamic evaluation of porcine bioprosthetic valves in the mitral position compared with cardiac catheterization.

Metheds Patients: From October 1964 to January 1966, 24 patients (7 men, 17 women) with porcine bioprostheses in the mitral position were studied 1 to 9 years (average 4) after operation. Patients were 16 to 55 years old (mean 31). Fourteen patients had normally functioning prostheses as defined by absence of symptoms or cliniFrom the Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia. Manuscript received August 8, 1986; revised manuscript received October 8,1986, accepted October 10.1986. Address for reprints: Mohamed Eid Fawzy, MRCP, Department of Medicine, King Faisal Specialist Hospital and Research Centre, Box 3354, Riyadh 11211, Saudi Arabia.

tkn y = 0.64x + 0.52), p
cal evidence of mitral stenosis or mitral regurgitation. They agreed to undergo this study as part of a followup protocol. Ten patients had abnormal valvular function and were symptomatic, with class II to IV (New York Heart Association) dyspnea and clinical evidence of mitral stenosis or mitral regurgitation. Doppler echocardiography was followed within 24 hours by cardiac catheterization. Twenty-one patients had Hancock valves (size 23 to 31 mm], 3 had CarpentierEdwards valves (size 31). Eleven patients were in sinus rhythm and 13 were in atria1 fibrillation. Doppler echocardiography: Doppler echocardiography was performed using a commercially available Honeywell Ultra Imager Machine in both pulsed and continuous-wave modes. Two types of transducer were used: a combined echo-Doppler transducer (3.5 or 2.5 MHz] and a continuous-wave Doppler transducer (2 MHz). Porcine mitral valve flow was recorded from the apical window with the sample volume positioned to obtain an optimal signal as parallel as possible to the assumed direction of flow. The mitral blood flow velocities were displayed graphically as a spectral analysis and recorded on hard copy at a paper speed of 50 or 100 mm/s. All patients had Doppler echocardiographic recordings of technical quality adequate to allow analysis. Mitral regurgitation was detected by scanning the left atrium, either from the apical or left parasternal window, and semiquantitatedg*10 as mild, moderate or severe by the extension of the

644

DOPPLER

EVALUATION

OF PORCINE

MITRAL

VALVE

regurgitantjet in the left atrium. The mitral diastolic pressuregradient was calculated using the modified Bernoulli equation.The mean diastolic pressuregradient was calculated by averagingthe early, mid- and end-diastolicgradients;an averageof 5 beatswas taken in patientswith atria1fibrillation and an averageof 3 beatsin patients in sinus rhythm. The mitral valve area of the bioprosthesiswas calculated by the pressure half-time method describedby Hatle for the native mitral valve.ll Doppler measurementswere made without knowledge of the catheterizationfindings. Cardiac catheterization: Cardiac catheterization was performed in standard fashion. Pressureswere measuredusing calibrated cathetersfilled with saline solution. An automated recording system was used (MEDDARS, Honeywell, Inc). The computercalculated the mean diastolic mitral valve gradient and mitral valve area of the bioprosthesis.A constantof 38 was used in the mitral valve area formula. Cardiac output was determined by thermodilution using a mean of 3 successivevalues with no more than 10% variation. Statistical analysis: Doppler measurements and cardiaccatheterizationdatawere comparedusinglin20 18 1

/

16. MEAN DOPPLER GRADIENT

” ‘* 11 10 8

NORMAL

3

6

9

12

MEAN CATHETER

15

16

21

24

27

GRADIENT

FIGURE 1. Good correlation between catheterization-determined and Doppler-determlned mean dlastollc pressure gradlent In 17 patients with normal function or obstructlon. The regression equation Is: Doppler mean gradient = 0.63 X catheter mean gradlent + 1.4.

ear regressionanalysis.Values are mean f standard deviation.

Results Pressure gradient: The Doppler-determinedmean diastolic gradient in the 17 patients (14 with normal and 3 with stenosedprostheses)was 4.5 to 16 mm Hg (mean7.8f 3.3);the catheterization-determinedmean diastolicgradient was4 to 23mm Hg (mean10.2f 4.8). There was a strong correlation: r = 0.9, SEE = 1.4 mm Hg, p
ranged from 4.5 to 9.5 mm Hg (mean 6.5 f 1.4);the catheterization-determined mean diastolic gradient ranged from 4 to 11 mm Hg (mean 8.4 f 1.7).The Doppler-determined valve area was 1.15to 2.0 cm2 (mean 1.54f 0.3)and the catheterization-determined valve area was 1.1to 2.5 cm2 (mean 1.6 f 0.4).There was no correlation between stent size and calculated valve area and no correlation between stent size and mean diastolic gradient (Fig. 3). Patients with valvular malfunction: Valvular stenosis(Fig. 4):Three patientshad bioprostheticstenosis, 2 of whom underwent reoperation (Table I]. The Doppler-determinedmean diastolic gradientwas 10to 16 mm Hg and the catheterization-determinedgradientwas 11to 23 mm Hg. The Doppler-determinedarea was 0.9to 1.1cm2and the catheterization-determined area was 0.7 to 0.9 cm2. Valvular regurgitation: Bioprosthetic valvular regurgitation was detected in 9 patients by Doppler echocardiography(Fig. 5). Two patients had mild regurgitationin addition to obstructionand 7 had isolat-

2.2 2.0 1.6.

Doppler Area

1.6. 1.4.

NORMAL STENOSIS

l n

S.E.E. = 0.16 .30

.60

.90

1.2

1.5

Catheter

1.6

2.1

2.4

2.7

3.0

Area

FIGURE 2. Correlatlon between catheterlzatlon-determlned and Doppler-determlned mitral valve area (MVA) In 17 patlents wlth normal function or obstructlon. The regresslon equatlon Is: Doppler YVA = 0.64 X catheter WA + 0.5.

FIGURE 3. Doppler spectral analysls of normal mitral posltlon from a patlent In slnus rhythm.

Hancock

valve

In the

March

TABLE I Doppler Valve Malfunction

Findings

Compared

I, 1987

THE

to Catheterization

JOW(NAL

and Operation

Doppler

P ‘/* T WW

AMERICAN

OF CARDIOLOGY

in Patients

with

Volume

59

645

Severe

Catheterization Mean Diastolic (jradlent (mm W

Mean Diastolic Gradient

Valve Area (cm*)

R

Valve Area (cm*)

(mm W

R

Operation

Regurgitation 1 2 3 4 5 6 7

217 218 240 273 246 246 225

137 200 117 135 110 100 90

9.5 13 18 15 11 17 9

1.6 1.1 1.9 1.8 2.0 2.2 2.4

S S S S S S S

14 26 9 31 27 19 25

M M N

21 23 11

s S S S S S S

t + + + + + +

M M N

+ +

Stenosis 8 9 IO

235 236 165

M = mild reauroitation: tation; Vmax 2 -kaxiAl reoperated.

220 235 200

15 16 IO

1 0.9 1.1

N = no reauroitation: P j/z T = pressure diastolic”infyow vekty; t = gross

half-time; pathology

0.9 0.7 0.9

R = regurgitation; S = severe regurglconflrmed at reoperation; - = not

ed, severeregurgitation.Findings were similar using angiocardiography.The 7 patientswith severeregurgitation all underwent reoperation. The maximal diastolic inflow velocity (Vmax) in the patients with severe mitral regurgitation was more than 2 m/s, but pressure half-time and valve area were normal for thesevalves (Table I).

pressuregradient per se is therefore of limited diagnostic value.12Ja Effective mitral valve area: Pressurehalf-time and derived mitral valve area are relatively independent of mitral flow and heart rate.12J3 We found goodcorrelation betwee? Doppler-determined and catheterization-determinedvalve area,similar to that reportedby Sagaret a1.8In detecting early malfunction of the miDiscussion tral valve bioprosthesiswe found it useful to have an Pressure gradient: We found good correlation be- early postoperativeDoppler study to serve as a basetween Doppler echocardiographyand catheterization- line. We recommend that all patients with a mitral determined mean diastolic mitral gradient, similar to bioprosthesisundergo Doppler study after operation results reported by Holen, Sagafl and their col- before leaving the hospital. leagues.However, we found overlap in the mean presNormally functioning valves: The mean diastolic sure gradient between patients with normally func- gradientsand mitral valve area for patientswith nortioning bioprostheticvalves and stenosedvalves. The mally functioning valveswere similar to values in oth-

FIGURE 4. Doppler spectral analysis of stenosed wards valve in the mitral position of a patient with

Carpentier-Edatriai fibriiiation.

FIGURE 5. Doppler severe regurgitation.

spectral analysis of Hancock reff, pulsed Doppler; right.

mitral valve with continuous wave.

646

DOPPLER

EVALUATION

OF PORCINE

MITRAL

VALVE

er published reports.8J4-16 The Doppler-determined mean diastolic mitral valve gradient did not separate patients with valve malfunction from thosewith normally functioning bioprosthetic valves; Doppler-determined pressure half-time and mitral valve area, however, reliably separatedthe 2 groups.Ryan et al7 reported poor correlation between pressurehalf-time and the stentsize.Williams et al5reportedpoor correlation between stent size and calculated valve area, similar to our findings. Valvular malfunction: We found that Doppler echocardiography was sensitive in detecting and quantitating valvular malfunction, both stenotic and regurgitant,asreportedby others.5p7J Ten patientswith malfunction of the porcine valve were diagnosedcorrectly by Doppler echocardiography.We found, asdid Ryan et aL7that patients with severe isolated mitral regurgitation had a Vmax of more than 2 m/s and elevated transvalvular gradients. However, pressure half-time was relatively unaffected,allowing separation from patients with stenotic lesions. Acknowledgment: We thank Alice McKinney for the illustrations. We also acknowledgeEdith Isorena, Kim Millward and Virginia Lacson for their invaluable help in the preparation of this manuscript.

References 1. Schapira JN. Martin RP, Fowles RE. Rakowski H, Stinson EB. French JW, Shumway NE, Popp RL. Two-dimensional echocardiographic assessment of patients with bioprosthetic valves. Am J Cardiol 1979;43:510-519.

2. Alam M, Lakier JB. Pickard SD, Goldstein S. Echocardiographic evaluation of porcine bioprosthetic valves: experience with 309 normal and 59 dysfunctioning vaives. Am J Cardiol 1983;52:309-315. 3. Kotler MN, Mintz GS. Panidis I. Morganroth J. Segal BL. Ross J. Noninvasive evaluation of normal and abnormal urosthetic valve function. lACC 1983;2:15l-173.

’

4. Holen J. Simonsen S, Froysaker T. Determination of pressure gradient in the Hancock mitral valve for non-invasive ultrasound Doppler data. Stand J Clin Invest 1981;41:177-183. 5. Williams GA, Lahovitz AJ. Doppler hemodynamic evaluation of prosthetic and bioprosthetic cardiac valves. Am J Cardiol l985;56:325-332. 6. Gross CM, Wann LS. Doppler echocardiographic diagnosis of porcine bioprosthetic cardiac valve malfunction. Am J Cardiol 1984:53:1203-1205. 7. Ryan T, Armstrong WF, Dillon JC. Feigenbsnm H. Doppler echocardiographic evaluation of patients with porcine mitral valves. Am Heart j 1986;111:237-244. 0. Sagar KB, Warm LS, Paulsen WHJ. Romhilt DW. Doppler echocardiographic evaluation of Hancock and Bjork-Shiley prosthetic valves. rACC 1986;7:681-687. 9. Abbasi AS, Allen MW, De Cristofaro D. Ungar I. Detection and estimation of the degree of mitral regurgitation by range-gated pulse Doppler echocardiography. Circulation 1980;61:143-147. 10. Quinones MA, Young JB, Waggoner AD, Ostojic MC, Ribeiro LGT, Miller RR. Assessment of pulsed Dopplerechocardiography in detection and quantification of aortic and mitral regurgitation. Br Heart J 1960;44:612-620. 11. Hatle L, Angelson B. Doppler ultrasound in cardiology: physical principle and clinical application. Philadelphia: Lea 8 Febiger 1985;115-119. 12. Hatle L, Angelson B. Tromsdal A. Non-invasive assessment of atrioventricular pressure half-time by Doppler ultrasound. Circulation 1979;60:10961104. 13. Libanoff AJ. Rodbard S. Atrioventricular pressure half-time measure of mitral valve orifice area. Circulation 1968;38:144-150. 14. Horowitz MS, Goodman DJ. Fagarty TJ, Harrison DC. Mitral valve replacement with the glutaraldehyde-preserved porcine heterograft. Clinical. hemodynamic, and pathological correlations. J Thorac Cardiovasc Surg 1974;67:885-895.

15. Johnson A. Daily P, Peterson Niwayama G. Functional evaluation position. Circulation 1975;52:suppI 16. Chaitman BR. Bonan R. Lepage CM. Hemodynamic evaluation of graft. Circulation 1979;60:1170-1182.

K. Le Winter M, Di Donna G. Blair G. of the porcine heterograft in the mitral 1:1-40-I-47. G. Tubau JF. David PR. Dyrda I, Grondin the Carpentier-Edwards porcine xeno-