Background: The purpose of this study was to evaluate whether abnormalities of free fatty acid metabolism are present before the onset of overt mechanical dysfunction in dogs with tachycardia-induced heart failure. We studied six dogs chronically instrumented to allow assessment of left ventricular function in the pressure-volume plane. Methods and Results: Free fatty acid clearance was assessed according to the washout rate of a free fatty acid analog, iodophenylpentadecanoic acid ([123I]PPA or IPPA). IPPA clearance was measured within 1 hour of the hemodynamic assessment. The animals were studied under baseline conditions and 11.7±3.6 days after ventricular pacing at a rate of 240 beats/min. Hemodynamic studies after pacing showed a nonsignificant increase in left ventricular end-diastolic pressure (11.7±4.7 to 17.4±6.5 mm Hg) and a nonsignificant decrease in the maximum derivative of pressure with respect to time (1836±164 vs 1688±422 mm Hg/sec). There was also no change in the time constant of left ventricular relaxation, which was 34.8±7.67 msec before and 35.3±7.3 msec after pacing. However, a significant prolongation in the clearance half-time of [123I]PPA, from 86.1±23.9 to 146.5±22.6 minutes (p<0.01) was found. Thus abnormal lipid clearance appears before the onset of significant mechanical dysfunction in tachycardia-induced heart failure. Conclusion: This suggests that abnormal substrate metabolism may play an important role in the pathogenesis of this condition.
- cardiac metabolism
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cardiology and Cardiovascular Medicine