Brett L Fowler | PubMed Health

PubMed2005

Aortic root dilatation may alter the dimensions of the valve leaflets.

OBJECTIVE: Valve-sparing surgery can be used in patients with dilated aortic roots and aortic insufficiency (AI) but has not become a common practice, in part because the spared valve may be incompetent. Our goal was to study how the dimensions of the aortic root and leaflets have changed in such patients. METHODS: Fourteen patients with dilated aortic root and AI were examined by transesophageal echocardiography. The annulus diameter, sinotubular junction (STJ) diameter, sinus height, leaflet free-edge length, and leaflet height were measured. Correlations among these dimensions and with the AI grades were explored. Measurements were also made in 19 normal human aortic valves from silicone molds. RESULTS: There was no evident change in the average diameter of the annulus between the normal valves and those in the dilated aortic roots. The STJ diameter was obviously increased in the dilated aortic roots; the aortic sinuses also appeared to be taller and the leaflets larger than normal. The leaflet free-edge length, the leaflet height, and the sinus height were found to increase with the dilated STJ diameter. The degree of AI was not found to correlate well with any of the dimensions measured. CONCLUSIONS: The dimensions of the leaflets may change parallel to aortic root dilatation with AI. Therefore, during valve sparing, it may be necessary to correct both the dilatation of the root and the leaflet free-edge length to achieve a competent valve.

Adult↗

PubMed2004

Does post-stenotic dilatation enhance collateral flow?

Our goal was to investigate whether post-stenotic dilatation (PSD) enhances collateral blood flow. In vitro experiments and computer modeling analysis were used to study the flow through stenotic segments and through collateral channels in the presence and absence of PSD. Pulsatile blood flow was provided by a left heart simulator primed with glycerol or normal saline. Pressure gradients across the stenosis were measured at different "cardiac" outputs. Computer models were constructed to simulate the experiments. Flow patterns and pressure drop across the stenosis were determined for a steady flow of 3 L/min. We observed that PSD was associated with a larger pressure drop across the stenosis than the absence of PSD when the flow was occurring through the stenosis only. There was, however, no difference in the pressure drop between the two geometries when the flow was occurring through both the stenotic orifice and the collateral channels when saline solution was used, but a small pressure difference prevailed for glycerol. At all different geometries there was considerable turbulence at PSD, and PSD geometry was found to be either at a disadvantage or at no advantage when compared to the tapered geometry for the total flow past the stenosis. The PSD geometry, however, enhanced the flow through the collateral while the flow through the orifice decreased concomitantly, resulting in no net increase in the total flow. This was true for any proportion of the total flow going through the collateral channels. For the total flow past the stenosis, PSD does not offer a benefit over tapered geometry.

Blood Circulation↗