Predictors of outcome of non-ischemic mitral valve surgery

BACKGROUND

Data on the risk stratification of patients undergoing mitral valve (MV) surgery for non-ischemic mitral disease are sparse. The present study seeks to define them in a contemporary cohort.

METHODS

193 consecutive patients referred to non-ischemic MV surgery were prospectively studied. Baseline characteristics and the type of surgery were analyzed with regard to operative and late mortality as well as functional outcome.

RESULTS

129 patients underwent MV replacement and 64 MV repair. MV replacement patients presented with more symptoms (p = 0.010), higher EuroSCORE (6.1 versus 5.6; p=0.009), more frequently underwent additional valve surgery (7.8 versus 0%; p = 0.003) and were more frequently female (p=0.048). Operative mortality was 3.1%, two thirds of operative deaths had additional surgery of the tricuspid valve (p = 0.019). Patients were followed for 5.2 ± 2.7 years. 1-, 3-, 5- and 7-year survival rates were 93-, 91-, 82-, and 79% in MV replacement patients versus 100-, 98-, 96-, and 89% in patients with MV repair (p = 0.015). However, by multivariate logistic regression, overall mortality was determined by additional surgery of the tricuspid valve (p = 0.0103), multivessel coronary disease (p = 0.026), and age (p<0.0001), but not by the type of surgery (p=0.066). Furthermore, the type of surgery did not influence functional outcome (p = 0.515).

CONCLUSIONS

Apart from age and coronary artery disease the need for additional tricuspid valve surgery significantly determines the outcome of non-ischemic MV surgery. The type of operation appears less important when the need for additional valve surgery and co-morbidities like coronary artery disease are taken into consideration.

Moderate patient-prosthesis mismatch after valve replacement for severe aortic stenosis has no impact on short-term and long-term mortality

BACKGROUND

The importance of moderate patient-prosthesis mismatch (PPM) for the prognosis of patients who undergo aortic valve replacement is unclear.

METHODS

The presence of PPM was assessed in 361 consecutive patients undergoing valve replacement for isolated severe aortic stenosis and related to perioperative and postoperative mortality. Indexed effective orifice areas (EOAi) were estimated for each type and size of prosthesis.

RESULTS

Using the previously proposed cut-off of EOAi <or=0.8 cm(2)/m(2), PPM was present in 54% of patients. Patients were followed for 4.1 (2.0) years. Survival tended to be slightly, but insignificantly, worse in the group with PPM (1-year, 3-year and 5-year survival 89%, 86% and 76% vs 92%, 88% and 82%; p = 0.21). However, patients with PPM were also older (p<0.0001), more often female (p<0.0001), more symptomatic (p = 0.001), more often had coronary artery disease (p = 0.04), triple vessel disease (p = 0.03) and hypertension (p = 0.01) and presented with a higher EuroSCORE (p<0.0001). By multivariate analysis only EuroSCORE and diabetes but not PPM were independent predictors of survival.

CONCLUSIONS

Moderate PPM is a frequent finding after aortic valve replacement. In our patient population it had no impact on short-term and long-term survival. It may therefore not be justified to recommend complex surgical interventions to avoid moderate PPM in patients undergoing aortic valve replacement for isolated severe aortic stenosis.

Doppler Echocardiographic Assessment of Valvular Regurgitation Severity by Measurement of the Vena Contracta: An In Vitro Validation Study

BACKGROUND

Noninvasive quantitation of valvular regurgitation remains a difficult problem. Measurements of the vena contracta (VC) by color Doppler echocardiography have been proposed but limited data are available on the actual accuracy of this method.

METHODS

To evaluate how closely the color Doppler VC reflects the true fluid dynamic VC and the anatomic regurgitant orifice and whether this measurement is affected by flow changes, various models of valvular regurgitation were studied in an in vitro flow circuit. The VC diameter was measured with color Doppler using two different ultrasound systems (Agilent Sonos 5500; Agilent Technologies Inc, Palo Alto, Calif and Vingmed CFM 800; GE Healthcare, Chalfront St Giles, UK). Optical planimetry of the anatomic regurgitant orifice was performed, the true VC diameter was determined by laser particle flow visualization.

RESULTS

Because of flow contraction, the true VC diameter was consistently smaller than the anatomic regurgitant orifice diameter. Anatomic orifice and true VC only marginally changed with flow rate. The diameter of the color Doppler VC, however, not only overestimated the anatomic orifice diameter by 45% to 60% and the true VC diameter by 130% to 160%, but was also highly affected by the flow rate and the ultrasound system. Despite these limitations a color Doppler VC diameter of 0.77 cm or more (Agilent) and 0.89 cm or more (Vingmed) detected severe regurgitation with a sensitivity of 93% and 84% and a specificity of 96% and 79%, respectively.

CONCLUSIONS

Color Doppler estimates of the VC markedly overestimate regurgitant orifice and true VC. In contrast to the true VC, Doppler measurements are significantly affected by flow rate and by the ultrasound system used. Nevertheless, they allow semiquantitative assessment of valvular regurgitation separating severe from nonsevere regurgitation with acceptable accuracy.

Doppler assessment of mechanical aortic valve prostheses: effect of valve design and size of the aorta

BACKGROUND AND AIM OF THE STUDY

Discrepancies between Doppler and catheter gradients have been reported for bileaflet aortic valve prostheses. Whether modifications in geometric design of newly developed bileaflet valves lead to a different Doppler-catheter gradient relationship has not been evaluated. Variable results have been reported for tilting-disc prostheses. In addition, the effect of aortic size on the Doppler-catheter gradient relationship remains unclear.

METHODS

Various sizes of On-X and Edwards Mira (identical with Sorin Bicarbon) bileaflet valves and Sorin Allcarbon tilting-disc aortic valves (19-25 mm) were studied in a pulsatile flow model. Doppler and catheter gradients were measured simultaneously. Aortic diameters between 1.8 and 4 cm were evaluated.

RESULTS

Correlation between Doppler and catheter gradients was excellent (r = 0.98-0.99 for peak and mean gradients), but in bileaflet valves Doppler significantly overestimated the corresponding catheter gradients as reflected by slopes of the regression lines (1.57-1.8). In the range of relevant gradients > or = 10 mmHg, Doppler exceeded catheter gradients by 40 +/- 17% (peak) and 39 +/- 16% (mean) in Mira valves, and by 46 +/- 19% (peak) and 43 +/- 14% (mean) in On-X valves. In the Sorin tilting-disc valve, Doppler accurately reflected catheter gradients (slopes of regression lines 1.05-1.14). The aortic diameter significantly influenced results in only tilting-disc valves, but in absolute terms the effect was clinically less relevant.

CONCLUSION

Discrepancies between Doppler and catheter gradients are common to all bileaflet valves, regardless of their specific geometric design, whereas tilting-disc valves must be considered individually. The influence of aortic size on the Doppler-catheter gradient relationship appears clinically to be less relevant in prosthetic valves.

Value and limitations of aortic valve resistance with particular consideration of low flow–low gradient aortic stenosis: an in vitro study

BACKGROUND

The calculation of valve resistance (R) rather than aortic valve area (AVA) has been proposed for the assessment of aortic stenosis (AS), based on the claim that it is less flow-dependent. Even more importantly, valve resistance has been reported to distinguish between truly severe and "pseudosevere" AS in patients with low cardiac output. However, the diagnostic value of valve resistance remains controversial.

METHODS AND RESULTS

Models of stenotic aortic valves (plates and nozzles) and biological stenotic valves were studied in a pulsatile in vitro circuit using Doppler ultrasound and direct pressure and flow measurements. Anatomic AVAs ranged from 0.5 to 1.25 cm2; cardiac output varied from 1.8 to 9.0 l/min. Effective AVA was calculated with the continuity equation. The orifices of the biological valves were recorded with a video camera for planimetry. In low flow-low gradient AS, truly severe stenosis was defined by an AVA remaining <0.85 cm2 after flow normalisation, whereas AVA increased beyond 0.85 cm2 in pseudosevere AS. In rigid stenoses, valve resistance increased significantly with flow, while in bioprostheses this flow dependence was partially masked by an actual increase of the anatomic orifice area. In low flow-low gradient AS, valve resistance was significantly smaller in pseudosevere AS compared to truly severe AS (129 +/- 28 vs. 176 +/- 33 dyne s cm(-5); p<0.001) at a similar baseline effective AVA. After the exclusion of datasets with mean gradients <15 and >35 mmHg, the difference in valve resistance between truly severe and pseudosevere AS was no longer significant (162 +/- 26 vs. 141 +/- 22 dyne s cm(-5); p=0.08). Nevertheless, valve resistance <120 dyne s cm(-5) was found only in pseudosevere stenoses while valve resistance >180 dyne s cm(-5) marked truly severe stenosis.

CONCLUSIONS

Valve resistance is flow-dependent and not superior to calculated AVA for the assessment of AS. In low flow-low gradient AS, valve resistance <120 dyne s cm(-5) identifies pseudosevere AS, whereas valve resistance >180 dyne s cm(-5) implies truly severe AS. However, values between 120 and 180 dyne s cm(-5) are nondiagnostic, requiring repeated AVA calculations after flow normalisation.