Analysis of the left ventricular early diastolic function in old myocardial infarction by gated radionuclide angiography

In order to determine the validity of the left ventricular (LV) diastolic function for evaluation of ischemic heart disease, gated radionuclide angiography was performed in 37 patients with transmural myocardial infarction (MI) [18: anterior, 19: inferior infarction] and 10 normal control subjects. LV ejection fraction (LVEF) was decreased in patients with anterior MI but not in those with inferior MI. Time to peak filling rate was not significantly prolonged in both anterior MI and inferior MI. Filling fraction was apparently reduced only in anterior MI. However, peak filling rate (PFR) was significantly reduced even in inferior MI as well as in anterior MI. PFR correlated well with LVEF in normal control, anterior MI and inferior MI. In both anterior MI and inferior MI, their coefficients were smaller than in controls. The normal PFR always indicated normal LVEF, while normal LVEF was not necessarily indicative of normal PFR. Results indicated that LV diastolic function estimated by equilibrium radionuclide angiography might reflect more precisely LV dysfunction in old MI than LV systolic function. The reduction of LV diastolic function in old MI was more prominent than that of LV systolic function. Therefore, it may be deduced that evaluation of LV diastolic function is essential to the estimation of the degree of ischemic myocardial cell damage and the efficacy of drugs on ischemia-induced LV dysfunction.

Reduction of plasma norepinephrine levels in response to brief coronary occlusion in experimental dogs

Although an increased plasma norepinephrine (NE) level is sometimes observed during angina pectoris, it is difficult to say whether sympathetic overflow is its cause. The left anterior descending coronary artery was occluded by intracoronary balloon for 3 minutes in 12 closed-chest anesthetized dogs. During occlusion, heart rate did not change but aortic pressure slightly decreased. Occlusion caused a significant reduction in both NE levels in the aorta (177 +/- 17 to 134 +/- 16 pg/ml, p less than 0.01) and in the great cardiac vein (GCV) 296 +/- 44 to 249 +/- 44 pg/ml, p less than 0.01). After surgical vagotomy, the occlusion increased NE levels in the aorta (227 +/- 44 to 278 +/- 43 pg/ml, p less than 0.01) and in GCV (384 +/- 76 to 444 +/- 81 pg/ml, p less than 0.01), showing the release of vagal inhibition. These results may be applicable to patients with transient anterior myocardial ischemia; if plasma NE increases without marked hemodynamic changes, it is suggested that the sympathetic overflow is not a result but a possible cause of the ischemia.

[Left ventricular diastolic properties in dilated cardiomyopathy, transmural myocardial infarction, and hypertrophic cardiomyopathy]

Left ventricular (LV) diastolic properties in dilated cardiomyopathy (DCM), transmural myocardial infarction (TMI), and hypertrophic cardiomyopathy (HCM) were evaluated. Radionuclide angiography and M-mode echocardiography were performed for 11 cases of DCM, 40 cases of TMI, 21 cases of HCM, and nine normal control subjects. In DCM, the peak filling rate (PFR) and filling fraction (FF) were significantly reduced, but the time to the peak filling rate (TPFR) was not prolonged. In TMI, both the PFR and FF were significantly reduced. Moreover, the TPFR was significantly prolonged in TMI as compared to DCM. Although depression of the PFR in HCM was not apparent, prolongation of the TPFR in HCM was marked. In DCM, there was good correlation between the PFR and left ventricular ejection fraction (EF) (r = 0.71, p less than 0.03). In TMI, there was a good correlation between the TPFR and the standard deviation of the LV phase angle histogram (SDP), indicating LV asynergy (r = 0.589, p less than 0.005). In HCM, both the FF and PFR correlated inversely with the LV wall thickness (r = -0.74, p less than 0.008; r = -0.581, p less than 0.03, respectively). These results indicate that various factors affect LV diastolic properties in heart disease, and that radionuclide angiography is a valuable technique for evaluating LV diastolic function.

[A comparative study of 4'-epi-doxorubicin and doxorubicin cardiotoxicities]

The cardiotoxicities of 4'-epidoxorubicin (4-epiDX) and doxorubicin (DX) were compared in rabbits. Thirty-one male NZW rabbits weighing 2.4 to 2.6 kg were used for each compound and 15 were kept as controls. DX or 4'-epiDX was administered intravenously with a dose of 0.8 mg/kg for 3 consecutive days a week for 5-10 weeks. Rabbits were sacrificed at 5, 8 and 10 weeks after initial administration. Under nembutal anesthesia, electrocardiogram, phonocardiogram and carotidgram were recorded. Light and electron microscopic studies of the heart were performed according to conventional methods. Myocardial alterations were semi-quantitatively evaluated with light microscopy, using a modified grading system derived from Bertazzoli. Twelve of the DX-treated rabbits and 4 of the 4'-epiDX-treated rabbits died after 5 weeks or later. In the electrocardiogram study, ST-T changes were less frequently observed in rabbits treated with 4'-epiDX than those with DX. Significant increases of PEP/LVET were observed in rabbits treated with DX for 8 and 10 weeks, similar increases were only observed while in rabbits treated with 4'-epiDX for 10 weeks. Histologically, both drugs produced myocardial degeneration and necrosis. The lesions were characterized by multiple vacuolization of myocardial cells, atrophy of myocardial cells, interstitial edema and fibrosis. Myocardial alterations induced by 4'-epiDX were qualitatively similar to those induced by DX, but were much less severe at the same cumulative dose. These results demonstrate that 4'-epiDX is less cardiotoxic than DX.