Systematic analysis of functional and structural changes after coronary microembolization: a cardiac magnetic resonance imaging study.
OBJECTIVE
Our study aimed to detect the morphological und functional effects of coronary microembolization (ME) in vivo by cardiac magnetic resonance (CMR) imaging in an established experimental animal model.


BACKGROUND
Post-mortem morphological alterations of coronary ME include perifocal inflammatory edema and focal microinfarcts. Clinically, the detection of ME after successful coronary interventions identifies a population with a worse long-term prognosis.


METHODS
In 18 minipigs, ME was performed by intracoronary infusion of microspheres followed by repetitive in vivo imaging on a 1.5-T MR system from 30 min to 8 h after ME. Additionally, corresponding ex vivo CMR imaging and histomorphology were performed.


RESULTS
Cine CMR imaging demonstrated a time-dependent increase of wall motion abnormalities from 9 of 18 animals after 30 min to all animals after 8 h (0.5 h, 50%; 2 h, 78%; 4 h, 75%; 8 h, 100%). Whereas T2 images were negative 30 min after ME, 4 of 18 animals showed myocardial edema at follow-up (0.5 h, 0%; 2 h, 6%; 4 h, 25%; 8 h, 17%). In vivo late gadolinium enhancement (LGE) was observed in none of the animals after 30 min, but in 33%, 50%, and 83% of animals at 2 h, 4 h, and 8 h, respectively, after ME. Ex vivo CMR imaging showed patchy areas of LGE in all but 1 animal (2 h, 83%; 4 h, 100%; 8 h, 100%). A significant correlation was seen between the maximum troponin I level and LGE in vivo (r = 0.63) and the spatial extent of ex vivo LGE (r = 0.76).


CONCLUSIONS
Our results show that in vivo contrast-enhanced CMR imaging allows us to detect functional and structural myocardial changes after ME with a high sensitivity. Ex vivo, the pattern of LGE of high-resolution, contrast-enhanced CMR imaging is different from the well-known pattern of LGE in compact myocardial damage. Thus, improvements in spatial resolution are thought to be necessary to improve its ability to visualize ME-induced structural alterations even in vivo.
Department of Cardiology, West German Heart Center, Essen, Germany. Frank.Breuckmann@uk-essen.de
Frank
F
Breuckmann
Kai
K
Nassenstein
Christina
C
Bucher
Ina
I
Konietzka
Gernot
G
Kaiser
Thomas
T
Konorza
Christoph
C
Naber
Andreas
A
Skyschally
Petra
P
Gres
Gerd
G
Heusch
Raimund
R
Erbel
Jörg
J
Barkhausen
D000818:Animals; D015415:Biomarkers / Q000097:blood; D003287:Contrast Media; D003324:Coronary Artery Disease / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D003326:Coronary Circulation; D004195:Disease Models, Animal; D004489:Edema, Cardiac / Q000209:etiology / Q000473:pathology; D004617:Embolism / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D019786:Gadolinium DTPA; D007261:Infusions, Intra-Arterial; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008833:Microcirculation; D008863:Microspheres; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000209:etiology / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D011137:Polystyrenes / Q000008:administration & dosage; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors; D019210:Troponin I / Q000097:blood
D015415:Biomarkers; D003287:Contrast Media; D011137:Polystyrenes; D019210:Troponin I; D019786:Gadolinium DTPA