Various stages of clip method.

<p>(A): Placing the unconscious mouse on a warm pad and shaving in the area of the precordial chest; (B): A small skin cut was made in the middle position of precordial chest; (C): a purse suture was made; (D) Dissecting and retracting the pectoral major and minor muscle to expose the 4th intercostal space; (E): Placing the mosquito clamp at the 4th intercostal space with the help of forceps; (F): Forcing the mosquito to open the pleural membrane and pericardium at the 4th intercostal space; (G) & (H): With the clamp slightly open and finger strength, the heart was smoothly and gently “popped out” through the window; (I)–(K): Once the LAD was located, an automatic clip applier was used to dispense a clip to ligate the LAD with a ~60–90 degree angle along the heart long axis; (L): Placing the heart back in to the intra-thoracic space promptly after ligation, therewith manual evacuation of air and closure of muscle and the skin by the pre-placed purse-string suture.</p

Inflammatory response in the two MI models.

<p>(A-C): Representative fluorescent micrographs showing the presence of CD68⁺ macrophages (green) in the hearts of SHAM (A), SMI (B), and CMI (C) groups. (D): Quantitation of CD68⁺ macrophages in each group at Day 21 (n = 3). <b>Cell apoptosis in the two MI models.</b> (E-G): Representative fluorescent micrographs showing the presence of TUNEL⁺ apoptotic cells (red) in the hearts of SHAM (E), SMI (F), and CMI (G) groups. (H): Quantitation of TUNEL⁺ cells (red) in each group at Day 21 (n = 3). Scale bars = 100 um. * indicates <i>P</i><0.05 when compared to SHAM group; NS indicates <i>P</i>>0.05 when compared to each other.</p

Surgical clip for LAD ligation.

<p>(A) & (B): Pictures showing the surgical clip dispenser and its tip containing the metal clip; (C) & (D): Schematic and gross heart picture showing left anterior descending artery (LAD) ligation by a surgical clip.</p

Total surgical time and LAD ligation time.

<p>(A): Total surgical time for the AMI model in SHAM (black bar), SMI (blue bar) and CMI (red bar) groups (n = 6); (B): Time required for left anterior descending artery (LAD) ligation in SMI (blue bar) and CMI (red bar) groups (n = 6). <b>Survival rates in the two MI models.</b> (C): Mice were subjected to SHAM or myocardial infarction (MI) surgery with either suture method or clip method and 4 hour perisurgery survival rate was recorded. (D): Long-term (21 day) survival rate. <b>Cardiac functions in the two MI models measured by echocardiography.</b> (E): Representative echocardiograph showing wall motion in SHAM, SMI and CMI groups at 21 day. (F & G): Left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) were measured by echocardiography at baseline (4 h post-MI) and 21 days afterward in SHAM, SMI and CMI groups (n = 6 animals per group). * indicates <i>P</i><0.05 when compared to SHAM group; ^# indicates <i>P</i><0.05 when compared to SMI group; NS indicates <i>P</i>>0.05 when compared to each other.</p

Short-term and long-term infarct sizes in the two MI models.

<p>(A): Representative photographs of TTC-stained heart sections obtained from SHAM, SMI and CMI groups at 24 hours after surgery, yellow arrow indicated infarcted area. (B) Representative micrographs of H & E stained heart sections obtained from SHAM, SMI and CMI groups at 21 day after surgery. (C) Representative micrographs of Masson’s trichrome stained heart sections obtained from SHAM, SMI and CMI groups at 21 day after surgery. (D) Quantitative analysis of infarct sizes from the Masson’s trichrome images (n = 6 animals per group). * indicates <i>P</i> < 0.05 when compared to SHAM; NS indicates <i>P</i>>0.05 when compared to each other.</p