Infrainguinal reconstruction with arm vein, lesser saphenous vein, and remnants of greater saphenous vein: a report of 257 cases.

PURPOSE: The purpose of this study was to evaluate the results of infrainguinal reconstructions with arm vein, lesser saphenous vein, and remnants of greater saphenous vein (ectopic vein grafts). METHODS: The records of 222 patients who underwent 257 bypasses were restrospectively reviewed. Most of the grafts were placed for rest pain or tissue loss (88%) and were secondary reconstructions (70%) to the infrapopliteal level (90%). Single-length vein grafts were constructed in 66% of cases, whereas 34% were composite vein grafts. RESULTS: Secondary graft patency was 70%, 52%, and 43% at 1, 3, and 5 years. Single-length grafts had significantly better patency rates at all intervals: 78% versus 56% at 1 year (p = 0.001), 60% versus 39% at 3 years (p = 0.004), and 52% versus 29% at 5 years (p = 0.002). The limb salvage rate was 69% at 5 years. CONCLUSIONS: Ectopic vein grafts with primarily arm vein are an acceptable alternative for infrainguinal reconstruction in the absence of suitable ipsilateral greater saphenous vein.

Achalasia in siblings. Clinical and genetic aspects.

Achalasia is rare in children; less than 2% of all patients with achalasia are less than 6 years old. Familial achalasia is extraordinarily rare, for an exhaustive search of the world literature yielded only 31 cases. Two additional cases are reported here. Based on an analysis of the reported cases in the literature coupled with our two cases, we have observed that familial achalasia is likely transmitted as an autosomal recessive trait. We recommend that all siblings of children with confirmed achalasia should either be studied by contrast roentgenography or be monitored closely for clinical signs of achalasia, especially if they are products of consanguineous parents.

The elastic modulus of canine aortic valve leaflets in vivo and in vitro.

Aortic valve leaflets undergo extraordinary flexion due to the complete reversal of their curvature during billions of cardiac cycles. The flexion stresses in the leaflet depend on its elastic modulus which we investigated in vivo and in vitro. In six dogs, we placed radiopaque markers on an aortic leaflet. Leaflet length was calculated from the marker positions recorded fluoroscopically. Aortic and ventricular pressures were recorded. Dogs were killed and leaflet stress-strain curves determined in vitro. Leaflet length in vivo decreased 10.4 +/- 4.7% from diastole to systole in each cardiac cycle. Using the law of LaPlace, pressure gradients across the leaflets were converted into the stresses in the leaflets. The leaflets had an initial "elastic phase" of low modulus in systole followed by an "inelastic phase" of high modulus in diastole. The elastic modulus was 2.4 +/- 0.7 x 10(6) dynes/cm2 in systole and 5.2 +/- 1.7 x 10(7) dynes/cm2 in diastole. These results were similar to those obtained in vitro. Since flexion rigidity is proportional to (elastic modulus) x (thickness)3, the lower modulus in systole greatly reduces flexion stresses in the leaflet and increases leaflet longevity. The higher elastic modulus in diastole prevents excessive bulging or prolapse of the leaflet while it is subjected to the diastolic pressure gradient. We conclude that a natural or prosthetic leaflet which is thickened or has a high elastic modulus throughout the cardiac cycle will have a greater flexion stress that could cause early failure.

The mechanism of opening of the aortic valve.

The mechanism of opening of the aortic valve was investigated in dogs by attaching radiopaque markers to the commissures and the leaflets. Analysis of abnormal cardiac cycles demonstrated that, when the ventricular pressure first equalled the aortic pressure, the intercomissural distances increased 9 percent, and the valve opened with a stellate orifice without forward flow and without a rise in aortic pressure. Further opening of the aortic valve was dependent on forward flow over a narrow range. A new mechanism of aortic valve opening is proposed. This mechanism results in minimal flexion stresses on the leaflets and is important for the longevity of the normal aortic valve. It can occur only if the leaflets arise from an expansile aortic root.