Mismatch between uniform increase in cardiac glucose uptake and regional contractile dysfunction in pacing-induced heart failure

Am J Physiol Heart Circ Physiol. 2007 Nov;293(5):H2747-56. doi: 10.1152/ajpheart.00592.2007. Epub 2007 Aug 17.

Abstract

Increased glucose utilization and regional differences in contractile function are well-known alterations of the failing heart and play an important pathophysiological role. We tested whether, similar to functional derangement, changes in glucose uptake develop following a regional pattern. Heart failure was induced in 13 chronically instrumented minipigs by pacing the left ventricular (LV) free wall at 180 beats/min for 3 wk. Regional changes in contractile function and stress were assessed by magnetic resonance imaging, whereas regional flow and glucose uptake were measured by positron emission tomography utilizing, respectively, the radiotracers [(13)N]ammonia and (18)F-deoxyglucose. In heart failure, LV end-diastolic pressure was 20 +/- 4 mmHg, and ejection fraction was 35 +/- 4% (all P < 0.05 vs. control). Sustained pacing-induced dyssynchronous LV activation caused a more pronounced decrease in LV systolic thickening (7.45 +/- 3.42 vs. 30.62 +/- 8.73%, P < 0.05) and circumferential shortening (-4.62 +/- 1.0 vs. -7.33 +/- 1.2%, P < 0.05) in the anterior/anterior-lateral region (pacing site) compared with the inferoseptal region (opposite site). Conversely, flow was reduced significantly by approximately 32% compared with control and was lower in the opposite site region. Despite these nonhomogeneous alterations, regional end-systolic wall stress was uniformly increased by 60% in the failing LV. Similar to wall stress, glucose uptake markedly increased vs. control (0.24 +/- 0.004 vs. 0.07 +/- 0.01 micromol x min(-1) x g(-1), P < 0.05), with no significant regional differences. In conclusion, high-frequency pacing of the LV free wall causes a dyssynchronous pattern of contraction that leads to progressive cardiac failure with a marked mismatch between increased glucose uptake and regional contractile dysfunction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cardiac Output, Low / etiology*
  • Cardiac Output, Low / metabolism*
  • Cardiac Pacing, Artificial / adverse effects*
  • Glucose / metabolism*
  • Myocardial Contraction*
  • Myocardium / metabolism
  • Swine
  • Swine, Miniature
  • Ventricular Dysfunction, Left / etiology*
  • Ventricular Dysfunction, Left / metabolism*

Substances

  • Glucose