Developments in cardiovascular valve technology - Biomaterials and Devices for the Circulatory System - page 100

Riess et al. 67 analyzed clinical and hemodynamic outcomes of 255 aortic
and 47 mitral Mosaic bioprostheses, with a cumulative follow-up of 1540
patient-years for the aortic and 250 patient-years for the mitral valve
replacements. Results were encouraging. Mean post-operative gradients in
the aortic valves at initial, 5 and 9 years were 13.7, 12.3 and 11.7 mmHg,
and in the mitral valves at initial, 5 and 7 years were 4.6, 4.1 and 3.9 mmHg.
Effective orifi ce areas in the aortic valves averaged 1.9, 1.8 and 1.8 cm 2 at
initial, 5 and 9 years, and in the mitral valves were 1.8, 2.2 and 2.3 cm 2 at
initial, 5 and 7 years. At 10 years, freedom from adverse events in the aortic
and mitral valve replacements were, respectively, 87 and 86% for throm-
boembolism, 98 and 100% for valve thrombosis, and 87 and 100% for
structural valve deterioration. This third-generation porcine bioprosthesis
continues to provide excellent hemodynamics and durability, with infre-
quent occurrences of valve-related adverse events.

4.4.5 Pericardial bioprosthesis: Ionescu
pericardial xenograft
In the early 1970s there was widespread disappointment with homograft
valves due to procurement diffi culties, and with the fascia lata valves due
to their high failure rate. At this time Ionescu 68 began constructing cardiac
valves from bovine pericardium, which is abundant and facile for valve
construction. These valves were mounted in a rigid titanium frame covered
with Dacron. These 'hospital made' valves had several disadvantages: the
production was not standardized, the pericardial strips were of variable
thickness, the fi xative was an impure glutaraldehyde, and a sodium meta-
periodate : ethylene glycol solution was used to expose the tissue. In 1976
the manufacture of the Ionescu pericardial xenograft was assigned to Shiley
Laboratories (Irvine, CA), which achieved a more standardized production
method including low pressure glutaraldehyde fi xation. These valves had a
low profi le and were mounted on a fl exible Delrin frame covered with soft
Dacron velour. This design greatly reduced stress on the valve cusps.
Ionescu et al. 62 reported initial results of 366 patients with Ionescu
pericardial xenograft implants in the mitral position. Sixty-eight patients
received 'hospital made' valves, and the other 298 received valves manufac-
tured by Shiley. A total of 250 patients had single mitral valve replacements,
including all those receiving 'hospital made' valves, and the other 116 had
multiple valve replacements. Of the 338 patients who survived the surgery,
233 had single mitral and 105 multiple valve replacements. Actuarial sur-
vival rate for the entire cohort was 72% at 11 years follow-up. There were
very few embolic events (0.6%/patient-year), and no valve thromboses.
Only seven valve failures (two cusp detachments, two cusp tears, three calci-
fi ed leafl ets) occurred, all of which were 'hospital made' valves. Thus, the

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