Effect of glutaraldehyde based cross-linking on the viscoelasticity of mitral valve basal chordae tendineae

BACKGROUND

Mitral valve failure can require repair or replacement. Replacement bioprosthetic valves are treated with glutaraldehyde prior to implantation. The aim of this study was to determine the changes in mechanical properties following glutaraldehyde fixation of mitral valve chordae.

METHODS

To investigate the impact of glutaraldehyde on mitral valve chordae, 24 basal chordae were dissected from four porcine hearts. Anterior and posterior basal (including strut) chordae were used. All 24 chordae were subjected to a sinusoidally varying load (mean level 2N, dynamic amplitude 2N) over a frequency range of 0.5-10 Hz before and after glutaraldehyde treatment.

RESULTS

The storage and loss modulus of all chordal types decreased following glutaraldehyde fixation. The storage modulus ranged from: 108 to 119 MPa before fixation and 67.3-87.4 MPa following fixation for basal chordae; 52.3-58.4 MPa before fixation and 47.9-53.5 MPa following fixation for strut chordae. Similarly, the loss modulus ranged from: 5.47 to 6.25 MPa before fixation and 3.63-4.94 MPa following fixation for basal chordae; 2.60-2.97 MPa before fixation and 2.31-2.93 MPa following fixation for strut chordae.

CONCLUSION

The viscoelastic properties of mitral valve chordae are affected by glutaraldehyde fixation; in particular, the reduction in storage moduli decreased with an increase in chordal diameter.

N-terminal pro-B-type natriuretic peptide levels and early outcome after cardiac surgery: a prospective cohort study

BACKGROUND

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a powerful predictor of cardiovascular outcome in many circumstances. There are, however, limited data regarding the utility of NT-proBNP or BNP levels in patients undergoing cardiac surgery. The current study assesses the ability of NT-proBNP to predict early outcome in this setting.

METHODS

One thousand and ten patients undergoing non-emergent cardiac surgery were recruited prospectively. Baseline clinical details were obtained and the European System for Cardiac Operative Risk Evaluation (EuroSCORE) and Parsonnet score were calculated. Preoperative NT-proBNP levels were measured using the Roche Elecsys assay. The primary endpoint was 30 day mortality.

RESULTS

Median NT-proBNP levels were 624 ng litre(-1) among patients who died within 30 days of surgery (n=29), compared with 279 ng litre(-1) in survivors [odds ratio (OR) 1.03 per 250 ng litre(-1), 95% confidence interval 1.01-1.05, P=0.001). NT-proBNP levels remained predictors of 30 day mortality in models including either the additive EuroSCORE (OR 1.03 per 250 ng litre(-1), P=0.01), the logistic EuroSCORE (OR 1.03 per 250 ng litre(-1), P=0.004), or the Parsonnet score (OR 1.02 per 250 ng litre(-1), P=0.04). Levels of NT-proBNP were also predictors of prolonged (>1 day) stay in the intensive care unit (OR 1.03 per 250 ng litre(-1), P<0.001) and of a hospital stay >1 week (OR 1.07 per 250 ng litre(-1), P<0.001). They remained predictive of these outcomes in regression models that included either the EuroSCORE or the Parsonnet score and in a model that included all study variables.

CONCLUSIONS

NT-proBNP levels predict early outcome after cardiac surgery. Their prognostic utility is modest-but is independent of traditional indicators and conventional risk prediction scores.

Socio-economic status and early outcome from coronary artery bypass grafting

OBJECTIVE

To determine the effects of socio-economic status (SES) on the outcome of coronary artery bypass grafting (CABG).

DESIGN

Prospective cohort study.

SETTING

Regional cardiac surgical unit.

PATIENTS

1994 consecutive patients undergoing non-emergency CABG.

MEASURES

SES was determined from the patient's postcode using Carstairs tables. The primary end-point was all-cause mortality at 30 days.

RESULTS

There were 50 deaths (2.5%) within 30 days of surgery. A higher Carstairs score demonstrated a trend towards increased 30-day mortality (odds ratio (OR) 1.09 per unit, 95% CI 1.00 to 1.20, p = 0.06). In a backward conditional model, including other predictors of early mortality, Carstairs scores were independently predictive (OR 1.12 per unit, 95% CI 1.01 to 1.24, p = 0.02). In a model including only Carstairs scores and the EuroSCORE, both were independent predictors of this outcome (OR for Carstairs score 1.11 per unit, 95% CI 1.00 to 1.22, p = 0.04). The 30-day mortality increases in each quartile of Carstairs scores, with patients in quartile 4 (most deprived) at significantly higher risk compared with quartile 1 (uncorrected OR 2.53 per unit, 95% CI 1.04 to 6.15; OR corrected for EuroSCORE, 2.56 per unit, 95% CI 1.03 to 6.34, p = 0.04 for both). Similarly, patients in the least affluent quartile were twice as likely to suffer a serious complication as those in the most affluent quartile (OR 2.14 per unit, 95% CI 1.32 to 3.46, p = 0.002). This increased risk was also independent of the EuroSCORE.

CONCLUSIONS

Lower SES is associated with a poorer early outcome following CABG and is independent of other recognised risk factors.

Thoracoscopic thoracic duct ligation for traumatic chylothorax

Traumatic chylothorax requires surgical intervention when conservative medical management fails to reduce chyle leakage. This usually entails thoracotomy or laparotomy. We report a case in which successful ligation of a torn thoracic duct was achieved using a video-assisted thoracoscopic technique.

Juxtacardiac costal osteochondroma presenting as recurrent haemothorax

A 21-year-old man presenting with a recurrent spontaneous haemothorax was found to have an osteochondroma arising out of the left 4th rib. This was penetrating the apical part of the heart. Surgical excision was uneventful.