Digital intravenous ventriculography: analysis and validation of wall thickness changes during ischemia and inotropic stimulation in dogs.

To assess regional ventricular wall thickening, we studied 8 open-chest dogs using digital intravenous ventriculography at a control stage, after subtotal and total coronary occlusion, and then after isoproterenol administration. In 3 dogs, 2 pairs of myocardial thickness crystals were implanted. Correlations of measures of wall thickness and percentage of wall thickening with crystal measures were excellent at the base (r greater than or equal to 0.97) and near the apex (r greater than or equal to 0.97). Four areas of the inferoapical wall muscle were measured: the base, mid-wall, distal wall, and apex. Four chamber dimensions were also examined: the long axis, base decreased with ischemia. At completion occlusion, it was -24.6 +/- 6% at the base, -27.3 +/- 5% at the mid-wall, -27.1 +/- 5% at the distal wall, and -24.7 +/- 5% at the apex. Percent thickening decreased with occlusion, although greater at the base and mid-wall than at the distal wall and apex. With isoproterenol, end-diastolic thickness increased only at the apex, with little change at the base, distal wall, and mid-wall. Percent thickening increased. In general, ischemia produced increases in end-diastolic hemichords with little change in the long axis. Isoproterenol reduced the hemichords, although the long axis did not change. We conclude the digital intravenous ventriculograms can be used to assess changes in wall thickness with high degrees of accuracy. Asymmetric thickening occurred at rest, with ischemia and with inotropic stimulation, being greatest at the apex and least at the base.