Impact of exercise capacity on myocardial high-energy phosphate metabolism.

31-Phosphorous magnetic resonance spectroscopy (31P MRS) is a unique tool to investigate IN VIVO high-energy phosphates (HEP) in the human heart. We hypothesized that physical capacity may be associated with myocardial HEP status. Healthy, male volunteers (n = 105, mean age 51 +/- 7 years) underwent bicycle ergometry with a stepwise increasing workload to determine maximal working capacity (MWC). Heart rate (HR) and blood pressure (BP) were measured continuously during exercise and 4 minutes of recovery. Further 31-Phosphorous 2-dimensional chemical shift imaging (31P 2D CSI) MRS was performed to assess myocardial HEP metabolism by determining phosphocreatinine to beta-ATP ratios (PCr/b-ATP) using a 1.5 tesla scanner. Volunteers with MWC > 230 Watt had significantly higher PCr/b-ATP ratios than those with MWC < 200 Watt (1.93 +/- 0.36 vs. 1.59 +/- 0.35; p < 0.001). Additionally, those with a recovery systolic (S)BP < 195 mmHg had significantly higher ratios than those with a recovery SBP > 195 mmHg (1.74 +/- 0.3 vs. 1.51 +/- 0.2; p < 0.05). We observed a linear correlation between the PCr/b-ATP ratio and MWC (r = 0.411; p < 0.001) and recovery SBP (r = - 0.290; p < 0.01). After statistical correction for age, these correlations remained significant. In this study, we observed a correlation of parameters of physical fitness determined by bicycle exercise testing and cardiac PCr/b-ATP ratios.

Coronary venous retroperfusion support during high risk angioplasty in patients with unstable angina: preliminary experience.

Synchronized coronary venous retroperfusion was used during coronary balloon angioplasty to support the ischemic myocardium of 20 patients with unstable angina and anatomy at high risk of a coronary event. Hemodynamics and left ventricular function were the major end points of the study. Coronary venous catheterization and retroperfusion were successfully performed in 15 patients. The target vessel was an unprotected left main artery in 2, left anterior descending artery in 10, left circumflex coronary artery in 1 and right coronary artery in 2 patients. A nonsupported balloon inflation (mean 44 +/- 13 s) was compared with a later retroperfusion-supported inflation (mean 145 +/- 21 s). Right anterior oblique left ventriculograms, aortic blood pressure, pulmonary artery pressure and thermodilution cardiac output were obtained before and during peak untreated and treated balloon inflations and on completion of angioplasty. All patients had either a baseline left ventricular ejection fraction less than 0.40 or greater than 40% of contracting myocardium estimated to be at risk for severe ischemia during angioplasty. The cardiac (liters/min per m2) and stroke work (g.m/m2) indexes decreased from mean baseline values of 2.5 +/- 0.52 and 52 +/- 15 to 1.7 +/- 0.47 and 27 +/- 12 (mean +/- SD), respectively, during nonsupported balloon inflations but decreased only to 2.1 +/- 0.52 (p less than 0.01 vs. nonsupported) and to 36 +/- 14 (p = 0.01 vs. nonsupported), respectively, during retroperfusion-supported inflations. Ejection fraction (n = 8) decreased from a baseline value of 55 +/- 13% to 27 +/- 7.3% during nonsupported inflations but only to 39 +/- 10% during retroperfusion-supported inflations (p = 0.01 vs. nonsupported). Regional wall motion (area change) in the ischemic (target) region was reduced from a baseline value of 49 +/- 17% to 11 +/- 16% during nonsupported inflations but only to 27 +/- 15% during retroperfusion-supported inflations (p less than 0.01 vs. nonsupported). All but two patients had a favorable hemodynamic response to retroperfusion. There were no serious adverse effects related to the procedures and no hospital deaths. It is concluded from this preliminary study that coronary venous retroperfusion appears to be safe, to provide hemodynamic support and to improve left ventricular function during angioplasty in patients with unstable angina and anatomy at high risk of a coronary event.