Doppler sonographic evaluation of the CarboMedics bileaflet valve prosthesis: one-year experience

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

Doppler Echocardiography of 79 Normal CarboMedics Mitral Prostheses: A Comprehensive Assessment Including Time-Velocity Integral Ratio and Prosthesis Performance Index

Few reports have been published on the normal Doppler-derived echocardiographic data for CarboMedics (CarboMedics Inc., Austin, TX) prosthesis function in the mitral position. The purpose of this study was to provide a comprehensive Doppler echocardiographic assessment of normal CarboMedics mitral prosthesis function in a large number of patients. All of the important Doppler-derived hemodynamic variables reported to date were used. The pressure half-time was less than 130 msec in all patients, and nearly all patients (95%) had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2, regardless of prosthesis size or left ventricular function. No significant differences were found among different prosthesis sizes for effective orifice area, effective orifice area indexed to body surface area, or prosthesis performance index.

Hemodynamic evaluation of normally functioning Sulzer Carbomedics prosthetic valves

The Sulzer Carbomedics prosthetic heart valve (CP) is a commonly used mechanical valve in clinical practice. In the present study, we used conventional and color Doppler echocardiography to assess the hemodynamics of normally functioning CP in the aortic (n = 73) and mitral (n = 127) positions. Our findings demonstrate no significant correlation of Doppler-measured peak and mean pressure gradients and effective orifice area with implanted valve size and actual orifice areas, measured directly by the manufacturer for CPs in both the mitral and aortic positions. However, it is still useful to measure effective orifice area by Doppler because a value in the normal or nonstenotic range points to an unobstructed prosthesis in the aortic or mitral position, in the absence of poor left ventricular ejection fraction. A value in the stenotic range could mean a normally functioning or obstructed prosthesis and, therefore, may need further investigation, such as assessment of valve leaflet motion by transthoracic or transesophageal echocardiography or fluoroscopy. Valve regurgitation as evaluated by color Doppler flow mapping was mild in practically all CPs in the aortic position, and in the majority of CPs in the mitral position.

Five-year follow-up after heart valve replacement with the CarboMedics bileaflet prosthesis

BACKGROUND

The CarboMedics valve is a relatively new, low-profile, bileaflet, mechanical prosthesis. The results of a prospective follow-up study after valve replacement with this prosthesis in a university hospital are presented.

METHODS

We implanted 640 CarboMedics prostheses in 583 patients in the aortic (n = 359), mitral (n = 167), or aortic and mitral positions (double valve replacement; n = 57). Patient ages ranged from 11 to 81 years (mean age, 58 +/- 12.3 years).

RESULTS

Overall hospital mortality was 9.0%; however, when high-risk urgent cases were removed from the calculation, the operative mortality fell to 4.5%. Follow-up was 98% complete, comprising 2,027 patient-years for a mean follow-up of 44 months (range, 6 to 72 months). Actuarial freedom from complications (linearized rates in parentheses) was as follows: late mortality, 85% +/- 2.0% (2.3%/patient-year); thromboembolism, 92% +/- 1.1% (1.6%/patient-year); anticoagulation-related hemorrhage, 87% +/- 1.2% (2.8%/patient-year); prosthetic valve endocarditis, 98% +/- 0.5% (0.1%/patient-year); and overall valve-related morbidity and mortality, 76% +/- 2.1% (4.3%/ patient-year).

CONCLUSIONS

The CarboMedics valve shows a low rate of valve-related complications comparable with other new mechanical heart valve prostheses.

Doppler Hemodynamics of CarboMedics Prosthetic Valves in Aortic Position at Rest and Exercise

To evaluate the size adequacy of CarboMedics prosthetic heart valves, Doppler pressure gradients after aortic valve replacement were determined at rest and immediately after exercise in 83 patients, at a mean time of 18.8 days after aortic valve replacement with CarboMedics prosthetic heart valves (31 standard and 52 R-series). There were 54 males and 29 females, average age 55 years; 12 had pure aortic stenosis, 47 had aortic regurgitation, and 24 had combined lesions. Exercise significantly increased (p < 0.01) the peak velocity (from 2.50 to 2.88 m/sec), the peak pressure gradient (from 25.9 to 34.6 mm Hg), and the mean pressure gradient (from 13.9 to 18.4 mm Hg). Significant differences were observed even in patients with seemingly large valve sizes. Significant correlation (p < 0.0001) was observed between pressure gradients at rest and immediately after exercise, as well as between pressure gradients and theoretical performance index. A theoretical performance index larger than 1.0 cm2/m2 was needed to obtain a postexercise Doppler peak pressure gradient of less than 60 mm Hg early after aortic valve replacement using either the Carbomedics standard or R-series prosthetic heart valves.

Hemodynamic assessment of carbomedics bileaflet heart valves by ultrasound: studies in the aortic and mitral positions

The bileaflet mechanical heart valve has become a popular prosthesis for implantation in both the aortic and mitral positions and a recent design by Carbomedics has received widespread use. Noninvasive assessment of these valves by Doppler ultrasound is important in characterizing their normal performance and in assessing the course of dysfunction. This study addressed the hypothesis that Doppler predicted pressure drops will correlate with catheter pressure drops within a valve size and position. A subhypothesis is that the pressure drops agree, and we expect this subhypothesis to fail due to pressure recovery effects. In a well-controlled in vitro model it was shown that the combined effects of pressure recovery and neglecting proximal velocities resulted in overestimation of catheter pressure drops for Carbomedics bileaflet valves. Inclusion of the proximal velocity reduced overestimation of peak pressure drops for aortic and mitral valves to clinically acceptable levels, and removed overestimation of mean pressure drops. Without correction for proximal velocity, overestimation of mitral pressure drops was reduced to 3.32% when means were calculated, but mean aortic pressure drops still overestimated the catheter standard significantly. It is concluded that proximal velocities should be included in Bernoulli analysis of Carbomedics heart valves. If the proximal velocity is not available, mitral valves may be best assessed using mean pressure drops, while aortic valve Doppler data, peak or mean, should be interpreted with caution.

The CarboMedics "top hat" supraannular prosthesis in the small aortic root

Twenty-three patients, 11 men and 12 women, with a mean age of 64 (range, 34 to 78) underwent aortic valve replacement (AVR) with a CarboMedics "Top Hat" supraannular prosthesis between March 1993 and August 1994. The top hat supraannular prosthesis, a standard bileaflet valve with the cuff transferred to the valve inflow level, allowed implantation of 21-mm, 23-mm, and 25-mm valves, where a standard 19-mm or 21-mm valve would have usually been placed. One patient who had been in preoperative cardiogenic shock died in the perioperative period. Another had an intraoperative cerebral embolism with permanent impairment. Follow-up on 22 of 23 patients over a mean period of 9 months revealed mean Doppler gradients of 18 +/- 6 mmHg, 15 +/- 2.8 mmHg, and 11 mmHg, for the 21-mm, 23-mm, and 25-mm valves, respectively. Functional improvement was noted, with 17 patients in New York Heart Association (NYHA) Class I and 6 in NYHA Class II, postoperatively, compared with 0 in Class I, 9 in Class II, 10 in Class III, and 4 in Class IV, preoperatively. One patient showed reduced postoperative ventricular function with fractional shortening below 25%. Pandiastolic regurgitation intrinsic to the valve graded as slight was noted in all patients. Other postoperative complications included one patient with anticoagulant-related gastrointestinal bleeding and one other with prosthetic valve endocarditis successfully treated with antibiotics. The CarboMedics top hat valve allows a gain in prosthesis size of 2 mm to 4 mm in the aortic position over standard prostheses, resulting in favorable postoperative hemodynamics.

Four-year experience with the CarboMedics valve: the North American experience. North American team of clinical investigators for the CarboMedics prosthetic heart valve

A multicenter prospective trial of the CarboMedics valve was initiated in July 1988. Twelve North American centers were included for the purpose of establishing the safety and efficacy of this new rotatable, bileaflet, pyrolytic-Carbon prosthesis. The study included 786 patients (using 891 valves) enrolled between July 1988 and August 1992. There were 447 male and 339 female patients from ages 2 to 83 years. Of the 618 primary replacement operations (including double valves), 393 were aortic and 292 were mitral valve replacements. Mean follow-up time was 16.1 months; 94.7% of patients had completed documentation up to and including one year. New York Heart Association functional class was III or IV for 84.4% of patients preoperatively, and I and II in over 96% of patients for the first three postoperative years. Survival for the entire group was 93% (622) at 1 month, 89% (504) at 1 year, 87% (213) at 2 years, and 85% (41) at 3 years. There were no significant survival differences between primary and repeat replacements or between aortic, mitral, and double-valve replacements. Primary replacement patients with concomitant procedures (n = 241) had slightly decreased survival rates compared with those who underwent isolated procedures (isolated survival rate, 92% [98]; concomitant procedure survival rate, 81% [59] at 2 years; p = 0.002). There was no valve failure. Linearized rates (events per 100 patient-years) in primary replacement patients after 30 days included the following: thrombosis, 0.39; thromboembolism, 0.92; hemolysis, 0.53; anticoagulant-related hemorrhage, 2.36; paravalvular leak, 0.92; endocarditis, 0.53; reoperation, 0.92; and explantation, 0.66.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and hemodynamic performance of the 19-mm Carpentier-Edwards porcine bioprosthesis

Because of concerns about the hemodynamic performance of 19-mm porcine valves, we retrospectively reviewed the clinical results and echocardiographic studies of 52 consecutive patients who received a 19-mm Carpentier-Edwards porcine bioprosthesis (model 2625) for aortic valve replacement from 1986 through 1991. Nearly 87% of the patients were women, the mean age was 69 years, and the mean body surface area was 1.63 +/- 0.27 m2. Seventy-three percent of the patients had pure aortic stenosis, 96% were in New York Heart Association classes III and IV, and 56% underwent urgent or emergent operation. Overall hospital mortality was 7.7% with a late mortality of 8.3% at a mean follow-up of 25 +/- 18 months. No patient experienced a valve-related complication, and 95% of surviving patients were in New York Heart Association classes I and II. Two-dimensional and Doppler echocardiography performed during the first postoperative week revealed a maximal instantaneous gradient of 44.7 +/- 13.0 mm Hg. In 43 patients for whom additional data were available, the mean gradient was 26.4 +/- 8.2 mm Hg with an effective orifice area of 0.85 +/- 0.18 cm2. This study defines the normal range of postoperative gradients across the 19-mm Carpentier-Edwards porcine valve and demonstrates that patients receiving this valve can achieve significant clinical improvement despite the presence of high transvalvular gradients measured by echocardiography.