Transthoracic left ventricular puncture for the assessment of patients with aortic and mitral valve prostheses: the Massachusetts General Hospital experience, 1989-2000

Accurate assessment of suspected prosthetic valve dysfunction is critically important as reoperation carries high risk. Noninvasive methods of hemodynamic assessment of patients with both aortic and mitral mechanical valves continue to be frustrated by the interference created by prosthetic material and direct left ventricular puncture may be required for definitive hemodynamic assessment. We report the hemodynamic and angiographic results and outcomes of 38 consecutive patients with double valve replacement who underwent left ventricular puncture as part of evaluation of possible prosthetic dysfunction. These results were compared with those obtained by noninvasive testing. We found noninvasive assessment alone to be unsatisfactory as measurements of regurgitation and stenosis correlated poorly with those obtained by direct left ventricular puncture. Important information that altered patient management was obtained from invasive assessment in 68% of cases with an acceptable rate of complications. Therefore, hemodynamic and angiographic assessment using transthoracic left ventricular puncture should be entertained in patients with mitral and aortic valve replacement presenting with congestive heart failure and suspected prosthesis dysfunction.

Left ventricular apical puncture: a procedure surviving well into the new millennium

We report two patients with a history of prior mitral valve and aortic valve replacement with St. Jude prosthetic valves, who were referred for repeat valve replacement after noninvasive assessment was suggestive of prosthetic valve malfunction. Both patients were managed medically after evaluation with direct left ventricular apical puncture revealed normal hemodynamics in the first and mild aortic stenosis in the second patient. These two cases illustrate that, despite the advancements in the noninvasive evaluation of prosthetic heart valves, left ventricular direct puncture continues to have an important value in the evaluation of patients referred for repeat valve replacement, and it can prevent unnecessary surgeries associated with a high risk of morbidity and mortality. Cathet. Cardiovasc. Intervent. 49:68-73, 2000.

Evaluation of prosthetic valve function and associated complications

Significant advances in imaging modalities have occurred to evaluate prosthetic valve function and associated complications. These developments involve predominantly the introduction of Doppler technology for the non-invasive determination of gradients and valve areas and TEE for an improved assessment of valve structure, function, and associated complications. The current role of cinefluoroscopy is mostly to complement TEE in the evaluation of motion of mechanical prosthetic valves in the aortic position. Cardiac catheterization is now rarely needed to assess valve function. Diagnosis of prosthetic valve obstruction can be performed in the majority of cases with transthoracic Doppler echocardiography. Differentiation of valve obstruction from normal valve function in small valves with high flow conditions, however, may be difficult. Because of this and the variability in normal valves among different prostheses, knowledge of the type and size of the implanted valve is essential. Patients and ultrasound laboratories are encouraged to seek and provide this information on a routine basis. Although transthoracic echocardiography is the main diagnostic modality for the serial evaluation of prosthetic valve function, it is important to recognize its limitations in assessing prosthetic mitral regurgitation and evaluating structural abnormalities of prosthetic valves. These are the situations in which TEE has the most impact. A summary of general indications of TEE in prosthetic valves is provided in Table 6. Finally, a baseline transthoracic Doppler study is essential in the overall follow-up and serial evaluation of valve function. For future comparisons, the best indices of valve functions are those obtained for patients as their own control, from a baseline Doppler echocardiographic study performed early after the operation.

Detection of Björk-Shiley Mitral Valve Dysfunction via Doppler Echocardiography

Fifty-eight patients with a Björk-Shiley (B-S) mitral valve were examined to study applicability of Doppler echocardiography in diagnosing and predicting the severity of prosthetic valve dysfunction. The effect of valve replacement on the hemodynamic performance at rest and during bicycle exercise was determined from serial echocardiographic data. The high pressure gradient group in which peak pressure gradients were assumed to be more than 15mmHg at rest, showed negative values of percent change in both stroke volume index (%ΔSVI) and left ventricular end-diastolic volume index (%ΔEDVI). All patients with high pressure gradients had poor exercise response of the left ventricle, whereas most patients with low pressure gradients showed good exercise response. The high pressure gradient group had significantly smaller mitral valve area than did the low pressure group. This suggests that impairment of inflow caused by the artificial valve, namely, prosthetic valve stenosis, is possibly a significant factor causing left ventricular dysfunction—notably a decrease in stroke volume during exercise. Reoperation was performed with good results in 5 of 58 patients because of high pressure gradients across the mitral valve prosthesis caused by tissue overgrowth. We conclude the high pressure gradient group is considered to be a reserved cohort of reoperation and periodical measurement of the pressure gradient via Doppler echocardiography can predict prosthetic valve dysfunction before it deteriorates significantly.

Assessing prosthetic heart valve function. Value of Doppler echocardiography and patient/prosthetic valve identity and follow-up card

Doppler echocardiography is being used increasingly in the follow-up of patients with valvular heart prostheses because it provides unique hemodynamic information about flow through prosthetic valves. A baseline checkup about 3 months after implantation is now recommended. We therefore now supply each patient with an identity and follow-up card for each particular prosthesis.

Doppler echocardiography in 180 normally functioning St. Jude Medical aortic valve prostheses. Early and late postoperative assessments

Limited Doppler echocardiographic data are available regarding velocities and gradients across normally functioning St. Jude Medical valves in the aortic position. To establish a standard reference for Doppler characteristics of normal aortic St. Jude Medical prostheses, we recorded continuous-wave Doppler measurements of peak and mean velocities and peak and mean gradients in 180 patients with normally functioning St. Jude aortic valves. There were 119 men and 61 women in the study; the mean age was 57 years. Minimal valvular regurgitation was present in 56 patients (31 percent). Velocities and gradients were reported in five patient groups according to valve sizes of 19 mm, 21 mm, 23 mm, 25 mm, and 27 mm; the mean gradients were 16 +/- 6, 16 +/- 6, 14 +/- 5, 12 +/- 5, and 12 +/- 6, respectively. Differences in velocities and gradients among the five valve sizes were not statistically significant (p = 0.05). Velocities and gradients were also analyzed in three patient groups according to time intervals after valve replacement. The first group (n = 64) underwent Doppler evaluation one to seven days postoperatively (mean, six days); the second group (n = 60) was evaluated after 8 to 30 days postoperatively (mean, 12 days); and the third group (n = 56) was evaluated after more than 30 days postoperatively (mean, 691 days). There were no significant differences in measurements for the three groups.

Long-term reproducibility of conventional Doppler analysis in patients with prosthetic valves

Long-term reproducibility of Doppler recordings made by the same investigator using the same ultrasound equipment was determined in 50 clinically stable patients. The mean interval between the first and second examination was 16 +/- 7 months. In 90% of the 33 patients with aortic prostheses, the relative difference between the first and second examination was less than 16% (mean value 9.1%) for the maximum instantaneous gradient and less than 17% (mean value 7.4%) for the mean gradient; the relative difference was less than 20% (mean value 8.5%) for the maximum flow velocity in the left ventricular outflow tract and less than 24% (mean value 10.8) for the maximum flow velocity ratio. In 90% of the 25 patients with mitral prostheses, the absolute difference between the first and second examination was less than 3 mmHg for the maximum instantaneous gradient, less than 2.5 mmHg for the mean gradient, and less than 20 msec for the pressure half-time. We conclude that long-term reproducibility of Doppler echocardiographic characteristics of prosthetic valve function is good as far as transprosthetic gradients or pressure half-time are concerned but is less so for maximum flow velocity in the left ventricular outflow tract and the maximum flow velocity ratio. Changes beyond the aforementioned values may represent a real change in prosthetic valve function.