Treatment of microvascular micro-embolization using microbubbles and long-tone-burst ultrasound: An invivo study

John J. Pacella*, Judith Brands, Frederick G. Schnatz, John J. Black, Xucai Chen, Flordeliza S. Villanueva

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)

Abstract

Despite epicardial coronary artery reperfusion by percutaneous coronary intervention, distal micro-embolization into the coronary microcirculation limits myocardial salvage during acute myocardial infarction. Thrombolysis using ultrasound and microbubbles (sonothrombolysis) is an approach that induces microbubble oscillations to cause clot disruption and restore perfusion. We sought to determine whether this technique could restore impaired tissue perfusion caused by thrombotic microvascular obstruction. In 16 rats, an imaging transducer was placed on the biceps femoris muscle, perpendicular to a single-element 1-MHz treatment transducer. Ultrasound contrast perfusion imaging was performed at baseline and after micro-embolization. Therapeutic ultrasound (5000 cycles, pulse repetition frequency=0.33Hz, 1.5MPa) was delivered to nine rats for two 10-min sessions during intra-arterial infusion of lipid-encapsulated microbubbles; seven control rats received no ultrasound-microbubble therapy. Ultrasound contrast perfusion imaging was repeated after each treatment or control period, and microvascular volume was measured as peak video intensity. There was a 90% decrease in video intensity after micro-embolization (from 8.6±4.8 to 0.7±0.8dB, p<0.01). The first and second ultrasound-microbubble sessions were respectively followed by video intensity increases of 5.8±5.1 and 8.7±5.7dB (p<0.01, compared with micro-embolization). The first and second control sessions, respectively, resulted in no significant increase in video intensity (2.4±2.3 and 3.6±4.9) compared with micro-embolization (0.6±0.7dB). We have developed an invivo model that simulates the distal thrombotic microvascular obstruction that occurs after primary percutaneous coronary intervention. Long-pulse-length ultrasound with microbubbles has a therapeutic effect on microvascular perfusion and may be a valuable adjunct to reperfusion therapy for acute myocardial infarction.

Original languageEnglish
Pages (from-to)456-464
Number of pages9
JournalUltrasound in medicine and biology
Volume41
Issue number2
DOIs
Publication statusPublished - 1 Jan 2015
Externally publishedYes

Keywords

  • Micro-embolization
  • Microbubble
  • Microvascular obstruction
  • Sonothrombolysis
  • Ultrasound

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