A Robust Percutaneous Myocardial Infarction Model in Pigs and Its Effect on Left Ventricular Function.

In this study, we created a reproducible myocardial infarction (MI) model in pigs characterized by a low mortality rate and significant changes in left ventricular function. After administering an arrhythmia prevention regimen, we created a 90-min balloon-induced percutaneous MI in 42 pigs below the first diagonal branch (D1) of the left anterior descending artery. Echocardiograms were performed before and 14 days after MI induction. Pigs with a > 30% decrease in left ventricular ejection fraction (LVEF) underwent electrophysiological mapping by the NOGA system. Our mortality rate was 4.8%. The incidence of ventricular fibrillation (VF) was 28.6%; all VF events were successfully resuscitated. At day 14, echocardiography and NOGA mapping confirmed transmural scar. LVEF decreased 41% from baseline. Radial and circumferential strain significantly decreased in the LAD distal to D1, and the LV showed dyssynchrony. An anti-arrhythmia regimen decreased mortality significantly, and our model induced dramatic functional changes. The basic procedures of the model included an arrhythmia prevention protocol and myocardial infarction creation, which effectively decreased mortality and provided a robust change in left ventricular (LV) function after 14 days.

Association between High Endocardial Unipolar Voltage and Improved Left Ventricular Function in Patients with Ischemic Cardiomyopathy.

We know that endocardial mapping reports left ventricular electrical activity (voltage) and that these data can predict outcomes in patients undergoing traditional revascularization. Because the mapping data from experimental models have also been linked with myocardial viability, we hypothesized an association between increased unipolar voltage in patients undergoing intramyocardial injections and their subsequent improvement in left ventricular performance. For this exploratory analysis, we evaluated 86 patients with left ventricular dysfunction, heart-failure symptoms, possible angina, and no revascularization options, who were undergoing endocardial mapping. Fifty-seven patients received bone marrow mononuclear cell (BMC) injections and 29 patients received cell-free injections of a placebo. The average mapping site voltage was 9.7 ± 2 mV, and sites with voltage of ≥6.9 mV were engaged by needle and injected (with BMC or placebo). For all patients, at 6 months, left ventricular ejection fraction (LVEF) improved, and after covariate adjustment this improvement was best predicted by injection-site voltage. For every 2-mV increase in baseline voltage, we detected a 1.3 increase in absolute LVEF units for all patients (P=0.038). Multiple linear regression analyses confirmed that voltage and the CD34(+) count present in bone marrow (but not treatment assignment) were associated with improved LVEF (P=0.03 and P=0.014, respectively). In an exploratory analysis, higher endocardial voltage and bone marrow CD34(+) levels were associated with improved left ventricular function among ischemic cardiomyopathy patients. Intramyocardial needle injections, possibly through stimulation of angiogenesis, might serve as a future therapy in patients with reduced left ventricular function and warrants investigation.

What to do when everything has failed: alternative treatment strategies for failure revascularisations.

Percutaneous coronary intervention and bypass grafting are effective for relieving symptoms and improving outcome in patients with coronary artery disease. Despite advances in medical treatment and revascularisation procedures, some patients with symptomatic ischaemic cardiomyopathy are not candidates for revascularisation. As life expectancy increases, interventional cardiologists and cardiac surgeons face patients with more complex disease, such as those with diffuse coronary disease that cannot be completely revascularised.

Validation of QwikStar Catheter for left ventricular electromechanical mapping with NOGA XP system.

Left ventricular electromechanical mapping (LVEM) is a method for mapping the left ventricular cavity in 3 dimensions by use of a catheter that samples points on the endocardial surface. These points provide data on unipolar voltage and linear local shortening, which can then be used to evaluate myocardial ischemia and viability. The new QwikStar multi-electrode catheter, which acquires data from multiple points simultaneously, potentially improves map quality and decreases mapping time in comparison with the single-point NogaStar catheter. Our study sought to validate the QwikStar catheter's LVEM capabilities in a porcine model of chronic ischemia.Eight pigs underwent ameroid placement over the proximal left circumflex artery, to induce chronic ischemia. In 60 days, LVEM was performed on each animal with the NogaStar and QwikStar catheters. Unipolar voltage and linear local shortening results were displayed in 9-segment polar maps. The unipolar voltage data from both maps were then correlated by means of linear regression.There were no adverse events during LVEM. Mapping time was similar for both groups (QwikStar, 44.6 +/- 25.62 min; NogaStar, 65.75 +/- 25.33 min; P = 0.13). Results of mean unipolar voltage maps acquired with the 2 catheters showed a moderate correlation (r =0.59, P <0.001). Selecting segments with more than 6 point samples increased the Pearson coefficient to 0.69 (P <0.001).Our findings show that the QwikStar catheter enables the reproducible performance of LVEM by sampling fewer points, which shortens procedure time, decreases manipulation of the left ventricular cavity, and might increase procedural safety.