Endothelial and non-endothelial coronary blood flow reserve and left ventricular dysfunction in systemic hypertension

OBJECTIVES: We evaluated the impairment of endothelium-dependent and endothelium-independent coronary blood flow reserve after administration of intracoronary acetylcholine and adenosine, and its association with hypertensive cardiac disease. INTRODUCTION: Coronary blood flow reserve reduction has been proposed as a mechanism for the progression of compensated left ventricular hypertrophy to ventricular dysfunction. METHODS: Eighteen hypertensive patients with normal epicardial coronary arteries on angiography were divided into two groups according to left ventricular fractional shortening (FS). Group 1 (FS >0.25): n=8, FS=0.29 ± 0.03; Group 2 (FS <0.25): n=10, FS= 0.17 ± 0.03. RESULTS: Baseline coronary blood flow was similar in both groups (Group 1: 80.15 ± 26.41 mL/min, Group 2: 100.09 ± 21.51 mL/min, p=NS). In response to adenosine, coronary blood flow increased to 265.1 ± 100.2 mL/min in Group 1 and to 300.8 ± 113.6 mL/min (p <0.05) in Group 2. Endothelium-independent coronary blood flow reserve was similar in both groups (Group 1: 3.31 ± 0.68 and Group 2: 2.97 ± 0.80, p=NS). In response to acetylcholine, coronary blood flow increased to 156.08 ± 36.79 mL/min in Group 1 and to 177.8 ± 83.6 mL/min in Group 2 (p <0.05). Endothelium-dependent coronary blood flow reserve was similar in the two groups (Group 1: 2.08 ± 0.74 and group Group 2: 1.76 ± 0.61, p=NS). Peak acetylcholine/peak adenosine coronary blood flow response (Group 1: 0.65 ± 0.27 and Group 2: 0.60 ± 0.17) and minimal coronary vascular resistance (Group 1: 0.48 ± 0.21 mmHg/mL/min and Group 2: 0.34 ± 0.12 mmHg/mL/min) were similar in both groups (p= NS). Casual diastolic blood pressure and end-systolic left ventricular stress were independently associated with FS. CONCLUSIONS: In our hypertensive patients, endothelium-dependent and endothelium-independent coronary blood flow reserve vasodilator administrations had similar effects in patients with either normal or decreased ...

Myocardial Contrast Echocardiography for the Assessment of Coronary Blood Flow Reserve

BACKGROUND: The assessment of coronary blood flow reserve measured by intracoronary Dopper syudy is a useful method for evaluation of functional impairment of coronary artery disease irrespective of significant anatomic stenosis. To validate the usefullness of myocardial contrast echocardiography in clinical assessment of coronary blood flow reserve, several variables analysed by myocardial contrast echocardiography were compared with coronary flow reserve measured by Dopper catheter study. METHODS: During the coronary angiography, coronary flow reserve was measured by intracoronary Dopper-tipped guidewire with coronary blood flow velocity ratio in 16 patients without angiographically significant coronary artery disease. For the measurement of coronary flow reserve, we analyzed the time-video intensity curve of short axis image of the left ventricle follwing infusion of sonicated hexabrix before and after intracoronary administration of adenosine. RESULTS: 1) There was no significiant difference or correlation between peak intensity, peak intensity ratio, washout time, half time of washout, and washout time ratio analysed by contrast echocardiography and coronary blood flow reserve measured by intracoronary Doppler study(p>0.05). But inverse correlation was observed between half time ratio of contrast washout and coronary flow reserve(r=0.63,p<0.05). 2) There was no significiant difference between non myocardial infarction group and myocardial infartion group in coronary flow reserve and half time ratio of contrast washout. 3) No significant difference was observed before and after administrantion of sonicated hexabrix in hemodynamic variables. CONCLUSION: Among several variables of myocardial contrast echocardiography analysis half time ratio of washout was significantly correlated with coronary flow reserve. Thus assesssment of coronary flow reserve with myocardial contrast echocardiography is promising method in the evaluation of dymamic coronary perfusion and myocardial viability.