Hemodynamic Performance of Mitroflow Aortic Pericardial Bioprosthesis – Optimizing Management for the Small Aortic Annulus

Abstract

Background: Documentation of the hemodynamics of the Mitroflow aortic pericardial bioprosthesis has been incomplete. The aim of the study was to provide reference effective orifice areas for the implant calculation of effective orifice area indexes to avoid prosthesis-patient mismatch. Methods: Echocardiograms were evaluated in 55 patients (39 females, 16 males), mean age 77.0 ± 6.9 years (range 51–90 years). The mean time of the studies was 11.0 months. The prosthesis sizes and numbers evaluated were 19 mm (n = 13), 21 mm (n = 19), 23 mm (n = 13) and 25 mm (n = 10). Results: Peak aortic velocities averaged from 2.2 to 2.7 m/sec, mean gradients from 10.6 to 15.1 mmHg, peak gradients from 20.7 to 29.7 mmHg, and effective orifice area (EOA) from 1.4 to 1.8 cm². When accounting for the subaortic velocity, mean gradients averaged from 7.5 to 10.0 mmHg, and peak gradients averaged 15.1 to 23.5 mmHg. The effective orifice area indexes ranged from 0.8 to 1.0 cm²/m². The mean postoperative left ventricular mass index was 101.6 gm/m². Conclusions: The in vivo effective orifice areas by valve size of the Mitroflow aortic pericardial bioprosthesis provide the opportunity of avoiding obstructive characteristics for all valve sizes, including optimizing the management of the small aortic annulus.

heart valve surgery - cardiovascular surgery - aortic disease - coronary bypass surgery - cardiomyopathy - heart disease

References

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Appendix 1 – Hemodynamic Evaluation Methodology

Hemodynamic parameters were calculated by the following equations according to published guidelines. Many studies of prosthetic heart valves have calculated pressure gradients using the complete Bernoulli equation, which adjusts for subvalvular pressures when calculating the pressure gradient through the prosthetic valve [1]. Current clinical practice, however, is to ignore the subvalvular pressure when calculating pressure gradients [2]. In this study, we presented pressure gradients calculated by both methods to aid comparison with other published studies.

Peak pressure gradient (mmHg) was calculated for each patient by the simplified Bernoulli equation as follows:

ΔP_peak = 4 (V₂)²

whereby V₂ is the transaortic peak velocity. If the subaortic peak velocity (V₁) was provided, then the peak pressure gradient was also calculated with the complete Bernoulli equation as follows:

ΔP_peak = 4 (V₂ ² – V₁ ²)

whereby V₂ is the transaortic peak velocity, and V₁ is the peak velocity in the LVOT.

Mean pressure gradient (mmHg) was calculated using the ultrasound instrument measurement package via planimetry of the waveform. Mean pressure gradient (ΔP_mean) adjusted for LVOT mean gradient was estimated by the V_rms method:

ΔP_mean = 4 (V_rmsd ² – V_rmsp ²)

where V_rmsd is the root mean square velocity distal to the valve in m/sec, and V_rmsp is the root mean square velocity proximal to the valve in m/sec.

Effective Orifice Area (EOA, cm²) was calculated using the standard continuity equation:

EOA = CSA × VTI_LVOT/VTI_AO

whereby CSA is the left ventricular outflow cross-sectional area in cm²; VTI_LVOT is the subaortic velocity time integral in cm, and

VTI_AO is the aortic velocity time integral in cm.

Mean ± SD was calculated for each hemodynamic measurement and presented by valve size.

Hemodynamic evaluation of prostheses documented in the literature may use either the simplified Bernoulli equation, neglecting subaortic velocity, or the complete Bernoulli equation, which appropriately accounts for subaortic velocity. Comparison studies of hemodynamics must be made in full awareness of the utilized technique by the respective investigators when making comparisons between prostheses.

Left ventricular mass regression was evaluated for both preoperative and postoperative measurements of left ventricular dimensions.

Left ventricular mass was calculated by the ASE cube method [3]:

LV mass = [0.8 × (1.04 [(LVEDD + IVSD + LVPWD)³–LVEDD³)] +  0.6]/1000

whereby LVEDD = left ventricular end-diastolic diameter, IVSD = end-diastolic inter-ventricular septum thickness, and LVPWD = end-diastolic LV posterior wall thickness.

References

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• a3 Gottdiener J S, Bednarz J, Devereux R et al. American Society of Echocardiography recommendations for use of echocardiography in clinical trials.  J Am Soc Echocardiogr. 2004;  17 1086-1119

Appendix 2

See [Table 6].

Table 6 Summary of effective orifice areas by valve size and manufacturer.

Author	Prosthesis	Effective orifice area by valve size [mm]*
		19	21	23	25	27
Garcia-Bengochea et al. (1)	Mitroflow	1.1 ± 0.1 (10)	1.3 ± 0.1 (21)	1.5 ± 0.2 (19)	1.8 ± 0.2 (11)	–
Jamieson et al. (current)	Mitroflow	1.4 ± 0.3 (12)	1.4 ± 0.4 (18)	1.8 ± 0.7 (12)	1.8 ± 0.4 (10)	–
FDA Study (2)	Mitroflow	1.1 ± 0.2 (30)	1.2 ± 0.3 (131)	1.4 ± 0.3 (185)	1.6 ± 0.3 (121)	1.8 ± 0.3 (37)
Borger et al. (3)	Hancock II	–	1.2 ± 0.1 (15)	1.2 ± 0.1 (15)	1.3 ± 0.1 (18)	1.88 (4)
Jamieson et al. (4)	CE‐SAV	–	1.5 ± 0.6 (8)	1.5 ± 0.5 (15)	1.4 ± 0.4 (16)	1.9 ± 0.7 (6)
Walther et al.† (5)	CE‐P	–	1.3	1.5	1.8	1.8
Botzenhardt et al. (6)	CE‐P	1.3 ± 0.3 (7)	–	1.7 ± 0.6 (11)	–	–
Eichinger et al. (7)	CE‐P	0.9 ± 0.04	1.4 ± 0.4	1.7 ± 0.3	1.8 ± 0.4	–
Khan et al. (8)	CE‐P	1.1 ± 0.3 (7)	1.3 ± 0.3 (22)	1.5 ± 0.4 (12)	–	–
Aupart et al. (9)	CE‐P	1.1 ± 0.2	1.4 ± 0.4	1.7 ± 0.5	1.9 ± 0.7	–
Botzenhardt et al. (10)	CE‐P	1.0 ± 0.3	1.4 ± 0.5	1.9 ± 0.6	2.1 ± 0.3
Flameng et al. (11)	CE‐P	1.3	1.5	1.7	2.0	2.1
Mhagna et al. (12)	CE‐P	1.2 ± 0.2 (40)	–	–	–	–
Eichinger et al. (7)	Mosaic	0.74 ± 0.3	1.2 ± 0.3	1.5 ± 0.5	1.9 ± 0.4	–
Walther et al.† (5)	Mosaic	–	1.2	1.4	1.65	1.8
Dalmau et al. (13)	Mosaic	–	1.5 ± 0.3 (6)	1.5 ± 0.2 (17)	1.9 ± 0.5	–
Botzenhardt et al. (6)	Mosaic	1.3 ± 0.7 (8)	–	1.5 ± 0.4 (34)	–	–
Botzenhardt et al. (14)	Mosaic	–	1.4 ± 0.4 (27)	1.7 ± 0.4 (36)	1.8 ± 0.4 (6)	2.6 ± 0.4 (5)
Borger et al. (3)	CE‐P Magna	1.2 (2)	1.3 ± 0.1 (8)	1.5 ± 0.1 (15)	1.5 ± 0.1 (22)	1.8 (1)
Dalmau et al. (13)	CE‐P Magna	–	1.6 ± 0.3 (5)	1.8 ± 0.3 (14)	2.2 ± 0.4 (24)	–
Botzenhardt et al. (6)	CE‐P Magna	1.47 ± 0.5 (10)	–	2.1 ± 0.6 (24)	–	–
Botzenhardt et al. (10)	CE‐P Magna	1.65 ± 0.8	1.7 ± 0.5	2.5 ± 1.2	2.3 ± 0.7	–
Botzenhardt et al. (6)	Sorin Soprano	1.3 ± 0.5 (4)	–	1.6 ± 0.4 (12)	–	–
Eichinger et al. (15)	Sorin Soprano	1.3 ± 0.4	1.6 ± 0.3	1.8 ± 0.2	2.3 ± 0.4	3.0 ± 0.2
Badano et al. (16)	Sorin Soprano	–	1.6 ± 0.2 (14)	1.9 ± 0.5 (24)	–	–
Badano et al. (16)	Sorin More	1.15 ± 0.3 (5)	1.5 ± 0.4 (12)	1.8 ± 0.5 (15)	–	–
* Standard deviation and number of patients are missing where not reported. † Recorded report by manufacturer. References: (1) García-Bengochea J, Sierra J, González-Juanatey JR et al. Left ventricular mass regression after aortic valve replacement with the new Mitroflow 12A pericardial bioprosthesis. J Heart Valve Dis 2006; 15 (3): 446–451 (discussion 451–452); (2) Summary of Safety and Effectiveness Data. FDA Premarket Approval Application Number P060038; (3) Borger MA, Borger A, Franka N et al. Carpentier-Edwards perimount magna valve versus Medtronic Hancock II: a matched hemodynamic comparison. Ann Thorac Surg 2007; 83: 2054–2058; (4) Jamieson WRE, Burr LH, Miyagishima RT. Carpentier-Edwards supra-annular aortic porcine bioprosthesis: Clinical performance over 20 years. J Thorac Cardiovasc Surg 2005; 130: 994–1000; (5) Walther T, Lehmann S, Falk V et al. Prospectively randomized evaluation of stented xenograft hemodynamic function in the aortic position. Circulation 2004; 110 (11 Suppl. 1): II74–II78; (6) Botzenhardt F, Eichinger WB, Bleiziffer S. Hemodynamic comparison of bioprostheses for complete supra-annular position in patients with small aortic annulus. J Am Coll Cardiol 2005; 45 (12): 2054–2060; (7) Eichinger WB, Botzenhardt F, Keithahn A et al. Exercise hemodynamics of bovine versus porcine bioprostheses: A prospective randomized comparison of the mosaic and perimount aortic valves. J Thorac Cardiovasc Surg 2005; 129: 1056–1063; (8) Khan S, Siegel RJ, Trento MA et al. Regression of hypertrophy after Carpentier-Edwards pericardial aortic valve replacement. Ann Thorac Surg 2000; 69: 531–535; (9) Aupart MR, Mirza A, Meurisse YA et al. Perimount pericardial bioprosthesis for aortic calcified stenosis: 18-year experience with 1133 patients. J Heart Valve Dis 2006; 15 (6): 768–775; (10) Botzenhardt F, Eichinger WB, Guenzinger R et al. Hemodynamic performance and incidence of patient-prosthesis mismatch of the complete supraannular perimount magna bioprosthesis in the aortic position. Thorac Cardiovasc Surg 2005; 53 (4): 226–230; (11) Flameng W, Meuris B, Herijgers P et al. Prosthesis–patient mismatch is not clinically relevant in aortic valve replacement using the Carpentier-Edwards perimount valve. Ann Thorac Surg 2006; 82: 530–536; (12) Mhagna Z, Tasca G, Brunelli F et al. Effect of the increase in valve area after aortic valve replacement with a 19-mm aortic valve prosthesis on left ventricular mass regression in patients with pure aortic stenosis. J Cardiovasc Med 2006; 7 (5): 351–355; (13) Dalmau MJ, Maríagonzález-Santos J, López-Rodríguez J et al. The Carpentier-Edwards perimount magna aortic xenograft: a new design with an improved hemodynamic performance. Interact Cardiovasc Thorac Surg 2006; 5 (3): 263–267; (14) Botzenhardt F, Gansera B, Günzinger R et al. Clinical and hemodynamic results of the mosaic bioprosthesis in aortic position. Z Kardiol 2003; 92 (5): 407–414; (15) Eichinger WB, Botzenhardt F, Wagner I et al. Hemodynamic evaluation of the Sorin Soprano bioprosthesis in the completely supra-annular aortic position. J Heart Valve Dis 2005; 14 (6): 822–827; (16) Badano LP, Pavoni D, Musumeci S et al. Stented bioprosthetic valve hemodynamics: is the supra-annular implant better than the intra-annular? J Heart Valve Dis 2006; 15 (2): 238–246

Additional Bibliography

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Ann Thorac Surg 2001; 71: S269–S272

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J Heart Valve Dis 2007; 16: 423–429

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Ann Thorac Surg 2001; 71: S282–S284

J Heart Valve Dis 2005; 14: 814–821

Eur J Cardiothorac Surg 2006; 30: 706–713

Ann Thorac Surg 2002; 73: 767–778