[The short- and medium-term ambulatory radionuclide study of left ventricular function (VEST) after aortocoronary...

The aim of the present study was to evaluate the variation in left ventricular function at 15 and 120 days after bypass surgery. Ten male patients (mean age 59.6 +/- 7 years) with previous myocardial infarction and coronary stenosis of at least two main vessels, underwent a radionuclide ambulatory monitoring of left ventricular function (VEST) during: handgrip test, mental stress test, walking, climbing stairs. These tests were carried out 8 +/- 2 days before (T0), 15 +/- 3 days (T1) and 120 +/- 11 days after coronary bypass; heart rate (HR), ejection fraction (EF), stroke volume (SV), and cardiac output (CO) were evaluated beat by beat before and during the test until the maximal HR was reached. Handgrip and mental stress tests did not induce significant variations in cardiac indices both before and after cardiac surgery. No variation in HR was observed before and after the test. During walking, at T0, HR increased from rest to maximal effort (p < 0.01) with a significant decrease in EF (p < 0.05); at T1 HR, EF, SV and CO increased with respect to rest (p < 0.01); AT T2 HR, EF (p < 0.05) and CO (p < 0.01) increased with respect to rest. Climbing stairs, at T0, HR increased (p < 0.01) and EF decreased (p < 0.05); at T1 HR, EF, CO (p < 0.05) and SV (p < 0.01) increased with respect to rest. At T2 an increase in HR (p < 0.01) and CO (p < 0.05) was observed at maximal effort with respect to rest. The statistical analysis on the percentage variations between baseline and maximal effort (climbing stairs) showed a significant increase in SV at T2 compared to T0 (p < 0.01). In conclusion, VEST during daily normal activities 15 days and 4 months after bypass surgery showed a significant increase in cardiac function indices. The best results obtained at T1 can be explained with the transient increase in adrenergic tone at the time of early postoperative period.