The effect of ischemia and isoproterenol on the pulmonary circulation in dogs. Analysis by digital intravenous angiography.
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Angiography↗
Biomedical subjects
K H Gerber
Publications and source records attributed to K H Gerber.
Quantitation of size of myocardial infarctions by computerized transmission tomography. Comparison with hot-spot and cold-spot radionuclide scans.
The current study evaluated the ability to quantitate the volume of myocardial infarctions when they are outlined by intravenously administered contrast media in the myocardial perfusion phase and in the phase of delayed contrast enhancement of the infarct. Quantitation by contrast media was assessed from computerized transmission tomography (CTT) scans of the ex situ heart and compared with quantitation by technetium-99m (99mTc)pyrophosphate (99mTc PYP) and thallium-201 (201Tl) scans of the same ex situ hearts. True volume was defined by histochemical morphometry. CTT during the contrast perfusion phase uniformly underestimated infarct size but had a good correlation with true volume (r = 0.87). CTT during enhancement phase correlated closely with true volume (r = 0.98) and most precisely measured true size (y = 1.06 X 0.23). The 99mTc PYP scan overestimated infarct volume (predictive overestimation of 6 to 199%) but had a good correlation with true volume (r = 0.87). 201Tl underestimated infarct volume but correlated well with true volume (r = 0.94). Thus, quantitation of infarct volume from CTT scans performed during either the perfusion or infarct enhancement phase after intravenous contrast media provides a good estimate of true infarct volume. Delineation of the infarct by contrast media in the ex situ heart is more precise during the phase of delayed enhancement of the infarct.
Animals↗
Effects of low osmolality contrast materials on coronary hemodynamics, myocardial function, and coronary sinus osmolality in normal and ischemic states.
The effects of intracoronary administration of contrast materials on regional and global left ventricular (LV) function and coronary sinus osmolality were assessed in six anesthetized dogs with segmental myocardial ischemia produced by critical stenosis of the circumflex coronary artery. Effects caused by Renografin (sodium meglumine diatrizoate), two new low osmolality contrast agents (Hexabrix and Hexabrix with added calcium ions), and metrizamide were evaluated. In a nonischemic state, Renografin produced an early (0-10 seconds) decrease in LV contractility followed by a late (10-20 seconds) rebound augmentation in contractility. In the presence of regional ischemia, there are prolongation of the depression of the myocardial contractile state. The monoacid dimer, Hexabrix, demonstrated a similar biphasic response, although the initial depression of myocardial contractility was significantly less than that observed with Renografin. Hexabrix with added calcium ions and metrizamide produced only augmentation in global and regional parameters of LV contractile function. This lack of depressant effects was also observed in the ischemic state. Renografin caused a significantly greater increase in coronary sinus osmolality (Tp) as compared with Hexabrix, Hexabrix-Ca++, and metrizamide. The increases in osmolality in response to the latter three contrast agents were statistically indistinguishable.
Animals↗
Comparative effects of ionic anc nonionic contrast materials on coronary and peripheral blood flow.
Contrast materials may alter coronary blood flow (CBF) by a direct vasodilating action or indirectly by changing determinants of myocardial oxygen requirements (MVO2). The current study compared the vasodilatory actions of ionic (Renografin 76, R76) and nonionic contrast materials (iohexol and metrizamide) after direct injection into the coronary and femoral circulation of anesthetized dogs. R76 did not cause a significantly greater increase in CBF compared with nonionic materials in spite of causing significantly greater increases in osmolality of blood in the coronary sinus. Concomitant with the peak increase in CBF, the ionic materials caused sharp decrease in peak left ventricular (LV) systolic pressure and dp/dt, while the nonionic materials increased these major determinants of MVO2. In contradistinction to the effects on CBF, ionic contrast material caused substantially and significantly greater increase in femoral blood flow, compared with the nonionic materials. In conclusion, these studies infer that the increase in CBF with contrast materials involves both indirect vascular and metabolic actions, while the increase in FBF is due to a direct vascular action.
Animals↗