Regional asynchrony in acute ischemia and stunning: an experimental myocardial velocity and strain rate imaging study
(English)Manuscript (preprint) (Other academic)
Objective: To quantify motion and deformation asynchrony using Doppler myocardial imaging (DMI) during acute total ischemia, and stunning of the posterior left ventricular wall (PW) in comparison with the interventricular septum (IVS).
Methods: Ischemia of the PW was induced in closed-chest pigs using an angioplasty balloon positioned in the circumflex coronary artery. Animals were divided into three groups: normal controls (Group I - n = 6), total ischemia (Group II - n = 8), and stunning (Group III - n = 6) induced by coronary occlusion with distal coronary perfusion maintained via a perfusion catheter coupled to a roller pump (Group III). In addition, a 2-step dobutamine challenge (5 and 10 µg.kg-1 .min-1) was performed in groups I and III. Doppler myocardial velocity and strain rate cineloops were acquired from a parasternal short axis view.
Results: The pre-ejection time (T1) and the duration of regional mechanical systole (SYS) became shorter with inotropic stimulation. During total ischemia T1 was prolonged and SYS shortened significantly compared to baseline values [62 ± 14 vs. 55 ± 13 ms (P < 0.05)], [164 ± 13 vs. 240 ± 27 ms (P < 0.001)], respectively. The fraction T1/SYS was accordingly higher. No changes were observed for the contra lateral non-ischemic wall. In group III, the post-ischemic myocardium had a similar response as non-ischemic myocardium to the dobutamine challenge.
Conclusion: Consistent changes in local pre-ejection time and regional mechanical systole are induced by intropic stimulation and by total ischemia. However, the response to intropic stimulation did not differ between normal and stunned myocardium.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-84958OAI: oai:DiVA.org:liu-84958DiVA: diva2:563278