Early changes in left ventricular anterior wall dynamics and coordination after coronary artery surgery

Resynchronization and strain recovery following reimplantation of anomalous coronary artery: a tissue Doppler and three-dimensional echocardiographic study

Resynchronization may play a significant role in recovery following surgical reimplantation of anomalous left coronary artery from the pulmonary artery (ALCAPA). Three-dimensional echocardiography and tissue Doppler may quantify this recovery. A 6-week-old infant presented with signs of congestive heart failure due to ALCAPA. Two-dimensional echocardiography showed a severely dilated left ventricular (LV) cardiomyopathy and the presence of ALCAPA was confirmed by catheterization. Three-dimensional echocardiography and tissue Doppler imaging showed severe abnormalities of systolic and diastolic synchrony and decreased contractility with a left ventricular ejection fraction (LVEF) of 13%. The infant underwent surgical coronary reimplantation and was discharged 5 weeks later with an LVEF of 54%. Serial quantitative assessment showed resynchronization and normalization of global LV function following reimplantation. However, segmental contractility improved significantly but remained depressed at discharge. The immediate recovery observed following reimplantation of anomalous coronary may be largely due to resynchronization.

Contribution of myocardium hydraulic skeleton to left ventricular wall interaction and synergy in dogs

The most premature motion change after coronary occlusion is early diastolic thinning of the ischemic left ventricular (LV) wall, with concomitant thickening of the normoperfused wall. We aimed 1). to demonstrate that these early changes are the result of the absence of fluid within the ischemic myocardium (hydraulic skeleton) rather than to cell anoxia and 2). to quantitate the contribution of the lack of hydraulic skeleton to left ventricular asynergy of contraction in seven anesthetized dogs submitted to acute, short-lasting circumflex artery (Cx) occlusion (ischemia) and to perfusion of the Cx with an oxygen-free solution (anoxia). We analyzed the time course of regional work index (WI, area of the LV pressure-wall thickness loop) and regional efficiency (defined as the ratio of WI to the maximum possible work). Interwall asynergy was defined as the difference between the regional efficiency of the anterior and posterior walls. After 9-10 s, posterior wall efficiency decreased 37 +/- 6% with anoxia and 72 +/- 3% with ischemia (P < 0.025), and interwall asynergy was 0 +/- 6% with anoxia and 32 +/- 5% with ischemia (P < 0.05). The contribution of absent hydraulic skeleton to interwall asynergy (calculated as the difference between %asynergy in anoxia and %asynergy in ischemia) was 30 +/- 8% (P < 0.05). In conclusion, the earliest wall motion change observed after acute coronary occlusion, namely ischemic wall thinning concomitant with normoperfused wall thickening during isovolumic relaxation, is the result of the absence of intracoronary fluid. The lack of hydraulic skeleton within the myocardium contributes approximately 30% to interwall asynergy.

Effect of coronary occlusion on left ventricular function with and without collateral supply during beating heart coronary artery surgery

OBJECTIVE

To study the effects of coronary occlusion and collateral supply on left ventricular (LV) function during beating heart coronary artery surgery.

DESIGN

Prospective intraoperative study, performed at baseline, during wall stabilisation, coronary artery occlusion, and 2 and 10 minutes after reperfusion. Transoesophageal M mode echocardiograms, simultaneous high fidelity LV pressure, and thermodilution cardiac output were measured. LV anterior wall thickening, thinning velocities, thickening fraction, regional work, and power production were derived. Asynchrony during the isovolumic periods was quantified as cycle efficiency.

SETTING

Tertiary referral cardiac centre.

PATIENTS

14 patients with stable angina, mean (SD) age 62 (7) years, undergoing left anterior descending artery grafting using the "Octopus" device.

RESULTS

Collaterals were absent in nine patients and present in five. Epicardial stabilisation did not affect LV function. Results are expressed as mean (SD). Coronary occlusion (15.6 (2) minutes) depressed anterior wall thickening (1.4 (0.6) v 2.6 (0.6) cm/s) and thinning velocities (1.4 (0.5) v 3.0 (0.6) cm/s), regional work (2.2 (0.8) v 4.6 (0.6) mJ/cm2), and power (21 (4) v 33 (5) mW/cm2) in patients without collaterals (p < 0.05 for all), but only wall thinning (3.5 (0.5) v 4.8 (0.5) cm/s, p < 0.05) in patients with collaterals. All returned to baseline within 10 minutes of reperfusion. Cycle efficiency and regional work were impaired at baseline and fell during occlusion, regardless of collaterals. Within 10 minutes of reperfusion both had increased above baseline.

CONCLUSIONS

Coronary occlusion for up to 15 minutes during beating heart coronary artery surgery depressed standard measurements of systolic and diastolic anterior wall function in patients without collaterals, but only those of diastolic function in patients with collaterals. Regional synchrony decreased in both groups. All disturbances regressed within 10 minutes of reperfusion.