Postoperative cardiac patients frequently are mildly hypothermic, yet the influence of hypothermia in left ventricular (LV) contractility has received little attention. To study the possible effects on mild hypothermia on LV function, six pigs were placed on partial right ventricular bypass, the hearts were electrically paced to control heart rate, and myocardial temperature was varied between 34° and 38°C. Using two pairs of orthogonally oriented sonomicrometer crystals in the left anterior descending (LAD) and left circumflex (LCX) distributions, we estimated regional work (the area within LV pressure-area loops) over a range of LV preloads. Diastolic function was assessed by measurement of the time constant of LV pressure decay during isovolumic relaxation. Regional work data were expressed as percentages of baseline (38°C and end-diastolic pressure of 10 mm Hg). To control for preload variations, regional work and time constants were calculated from beats with end-diastolic areas within 0.1% of baseline. Regional work (mean ± SEM) declined from 85.1 ± 6.7% at 38°C to 31.9 ± 4.4% at 34°C. Time constants were prolonged from 44.8 ± 2.5 msec at 38°C to 61.6 ± 2.7 msec at 34°C. These data demonstrate a marked depression of LV contractility, even at mild levels of hypothermia that may be encountered clinically after cardiac operations.
|Original language||English (US)|
|Number of pages||5|
|Issue number||5 SUPPL.|
|State||Published - Jan 1 1989|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)