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Aortic valve replacement. A randomized study comparing the Björk-Shiley and Lillehei-Kaster disc valves. Late
Insights
The Lillehei-Kaster (L-K) aortic valve, especially smaller sizes, creates significant flow resistance, leading to poorer patient outcomes compared to Björk-Shiley (B-S) valves. This study highlights the clinical unacceptability of high-pressure gradients with L-K valves.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Clinical Medicine
Background:
- Aortic valve replacement is a critical procedure for patients with valvular heart disease.
- Björk-Shiley (B-S) and Lillehei-Kaster (L-K) mechanical valves have been used historically.
- Patient selection and valve performance are crucial for long-term outcomes.
Purpose of the Study:
- To clinically and hemodynamically evaluate patients with Björk-Shiley (B-S) and Lillehei-Kaster (L-K) aortic disc valve prostheses.
- To compare the hemodynamic performance and clinical outcomes between B-S and L-K valves, particularly in patients with narrow aortic roots.
- To assess the impact of valve size on pressure gradients and left ventricular end-diastolic pressure (LVEDP).
Main Methods:
- Randomized study of 78 patients undergoing aortic valve replacement.
- Clinical and hemodynamic evaluations, including cine-aortography (n=75) and transseptal left ventricular catheterization (n=42).
- Over-representation of patients with narrow aortic roots to assess performance in challenging anatomies.
Main Results:
- Striking clinical improvement observed in most patients.
- Significantly lower peak-to-peak and mean systolic pressure gradients across B-S valves compared to L-K valves, especially in smaller sizes (14 & 16).
- Significant decrease in LVEDP to normal levels in the B-S group, while L-K group showed persistently elevated LVEDP.
Conclusions:
- Lillehei-Kaster (L-K) valves, particularly sizes 14 & 16, exhibit unacceptably high flow resistance.
- Björk-Shiley (B-S) valves demonstrate superior hemodynamic performance and better LVEDP normalization post-operation.
- The findings suggest limitations of small L-K valves in clinical practice due to significant pressure gradients.
Abstract:
In this study, 78 randomized patients with either Björk-Shiley (B-S) or Lillehei-Kaster (L-K) aortic disc valve prostheses were re-admitted for clinical and haemodynamic evaluation. The patients were selected that those with narrow aortic roots were over-represented. Cine-aortography was carried out in 75 patients and left ventricular catheterisation via the transseptal approach was performed in 42. The clinical improvement was striking, although the number of patients still incapacitated was relatively large in patients with the small L-K valves (Nos. 14 & 16). Peak-to-peak and mean systolic pressure differences across the valves were significantly lower in the B-S than in the L-K valves, particularly when the small valve sizes were compared. Left ventricular end-diastolic pressure (LVEDP), which was elevated in most patients before operation, decreased significantly to normal levels in the B-S group. In the L-K group, LVEDP did not decrease significantly and was on the average still above the normal level after operation, probably due to the relatively large pressure gradients. The study indicates that the L-K valves Nos. 14 & 16 in particular represents a resistance to flow that is too large to be acceptable in clinical practice.