Masami Miyamae

Ventricular expression of brain natriuretic peptide in hypertrophic cardiomyopathy.

BackgroundBrain natriuretic peptide (BNP), as a cardiac hormone, is expressed together with atrial natriuretic peptide (ANP) in the ventricles in congestive heart failure. However, the ventricular expression of BNP in hypertrophic cardiomyopathy (HCM) with normal systolic function is still unclear. Methods and ResultsThe study population consisted of 39 HCM patients with asymmetric septal hypertrophy and 10 control subjects without any specific cardiac disease. Eleven cases of HCM were obstructive (HOCM), and the other 28 cases were nonobstructive (HNCM). All of these patients had a normal ejection fraction. Immunohistochemical analysis of endomyocardial biopsy specimens with specific monoclonal antibodies showed BNP immunoreactivity in the HOCM group (5/10, 50%) but not in the HNCM group (0/22) or in control subjects (0/5). In HOCM, left ventricular end-diastolic pressure was significantly higher in the BNP-positive patients than the BNP-negative patients. Histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis were greater in BNP-positive patients than BNP-negative patients in HCM. However, the expression had no significant relation with other clinical parameters. The elevation of the BNP plasma level versus control subjects was marked in both HOCM (85-fold) and HNCM (23-fold). By contrast, the elevation of the ANP plasma level versus control subjects was mild in HOCM (5.7-fold) and HNCM (4.2-fold). The ratio of BNP level to ANP level was higher in HOCM (4.16) than in HNCM (1.46) and control subjects (0.28), and it was higher than the ratio previously reported for severe congestive heart failure (1.72). ConclusionThese findings suggest that BNP is expressed in the ventricular myocytes of HCM with normal systolic function. In HOCM, ventricular expression of BNP may be augmented in response to both obstruction and diastolic dysfunction.

Histologic studies in percutaneous transluminal coronary angioplasty for chronic total occlusion: Comparison of tapering and abrupt types of occlusion and short and long occluded segments

OBJECTIVESnThe purpose of this study was to examine the histologic-angiographic correlates of chronic total coronary occlusion and to explain why a tapering type of occlusion and short occluded segments are favorable for percutaneous transluminal coronary angioplasty.nnnBACKGROUNDnCoronary angioplasty is less successful for vessels with chronic total occlusion than for highly stenotic but patent vessels. Several clinical and angiographic factors determining the rate of initial success have been investigated, but the underlying histologic features are not clear.nnnMETHODSnTen autopsy hearts that showed chronic total coronary occlusion on cineangiography performed < or = 3 months before death were selected. In all, the estimated duration of occlusion was > 1 year. At autopsy, postmortem angiography was performed and hearts were fixed with 10% buffered formalin. Occluded segments were sectioned transversely and serially into slices 10 microns thick. Every five slices were stained in hematoxylin-eosin and elastic van-Gieson.nnnRESULTSnTen hearts with chronic total coronary occlusion were angiographically classified into five with a tapering and five with an abrupt type of occlusion and seven with a short (< or = 15 mm) and three with a long (> 15 mm) occluded segment. Histologically, the occluded segment was composed of loose or dense fibrous tissue, atheroma, small vascular channels and calcified tissue. Reconstruction of the serial preparations showed that small lumen recanalized areas (diameter 160 to 230 microns) with surrounding loose fibrous tissue penetrated the occluded segment in four hearts with occlusion of the tapering type and a short occluded segment. In these four cases, the lack of anterograde flow on cineangiography could be explained by the presence of rich collateral flow. In three cases of the abrupt type of occlusion with a short occluded segment, a mass of loose fibrous tissue penetrated the occluded segment. In hearts with a long occluded segment (one with a tapering type of occlusion and two with an abrupt type), there was no recanalization and loose fibrous tissue was dispersed in the occluded segment.nnnCONCLUSIONSnChronic total coronary occlusion of the tapering type or with a short occluded segment, or both, is possibly favorable for angioplasty, because small lumen recanalized areas or loose fibrous tissue penetrates the occluded segment and may form a route for successful angioplasty.

Preconditioning improves energy metabolism during reperfusion but does not attenuate myocardial stunning in porcine hearts.

BackgroundIt has been reported that a brief period of coronary occlusion and reperfusion slows the rate of ATP depletion during subsequent sustained ischemia as well as limiting infarct size. However, it has not yet been determined whether ischemic preconditioning also has an effect on the functional and metabolic recovery of stunned myocardium. Our study was designed to address this problem. Methods and ResultsFarm pigs were anesthetized with fluothane and randomly assigned to either a control group or a preconditioned group. The control group (n=15) underwent 15 minutes of coronary occlusion followed by 120 minutes of reperfusion. The preconditioned group (n=14) underwent two episodes of 5-minute occlusion and 5-minute reperfusion followed by 15 minutes of occlusion and 120 minutes of reperfusion. This protocol was designed to exclude the stunning effect of the preconditioning procedure itself as much as possible besides preconditioning the heart. A pair of ultrasonic crystals was implanted in the area at risk perfused by the left anterior descending coronary artery. 31P-nuclear magnetic resonance spectroscopy and sonomicrometry were performed alternately. Regional myocardial blood flow (RMBF) was determined with colored microspheres. At 15 minutes of sustained ischemia, phosphocreatine (Pcr), ATP, and intracellular pH were significantly better preserved in the preconditioned group (Pcr: control/preconditioned, 1±1%/o/14

Blockade of ATP-sensitive K+ channels attenuates preconditioning effect on myocardial metabolism in swine:: Myocardial metabolism and ATP-sensitive K+ channels

1%; ATP:control/preconditioned, 66

932-90 Transient Adenosine Infusion and Washout Before Ischemia Protects the Heart Against Metabolic Damage During Ischemia and Reperfusion, but Does not Attenuate Stunning in Pigs – Comparison with Ischemic Preconditioning

2%1/74

1005-76 Preconditioning with 15-min Ischemia Extends Myocardial Infarct Size After Subsequent 30-min Ischemia in Rabbits

2%; pH:control/preconditioned, 632

Ischemic preconditioning elevates cardiac stress protein but does not limit infarct size 24 or 48 h later in rabbits.

0.07/6.52

Transient adenosine infusion before ischemia and reperfusion protects against metabolic damage in pig hearts

0.05; P<.05). After reperfusion, ATP increased progressively and was almost normalized at 120 minutes of reperfusion in the preconditioned group (control/ preconditioned, 73

Preconditioning with 15-minute ischemia extends myocardial infarct size after subsequent 30-minute ischemia in rabbits

4%/95

Dobutamine prevents both myocardial stunning and phosphocreatine overshoot without affecting ATP level.

3%; P<.05). Overshoot of Pcr (which indicates that the energy generating system is operating better than energy utilizing system) persisted in preconditioned hearts but disappeared rapidly in controls (control/preconditioned, 104