Peak rapid filling rate (PRFR) is often used clinically as an index of left ventricular relaxation, i.e., early diastolic function. This study tests the hypothesis that a function atrioventricular pressure difference and hence influenced by atrial well relaxation. As indexes, we chose at crossover (PCO), time constant (T) assumed exponential decline in pressure. We accurately determined magnitude timing parameters conscious dogs direct measurement phasic mitral flow (electromagnetically)...

We developed a portable needle-probe videomicroscope with charge-coupled device (CCD) camera to visualize the subendocardial microcirculation. In 12 open-chest anesthetized pigs, sheathed needle probe doughnut-shaped balloon and microtube for flushing away intervening blood was introduced into left ventricle through an incision in atrial appendage via mitral valve. Images of microcirculation beating heart magnified by 200 or 400 on 15-in. monitor were obtained. The phasic diameter change...

Poststenotic blood flow velocities were evaluated in nine patients with 75% to 99% stenosis of the left anterior descending coronary artery (LAD) during bypass graft surgery. We used 20 MHz 80-channel pulsed Doppler velocimeter developed our laboratory. An operator placed a specially designed probe on native LAD his fingers. Before induction extracorporeal circulation, measured at several locations distal stenosis. The poststenotic rich systolic component reduced diastolic component....

To elucidate the role of loading sequence in afterload-dependent slowed relaxation hearts situ, time constants (Texp from best exponential fitting method and TL semilogarithmic method) isovolumetric left ventricular (LV) pressure decay were studied nine anesthetized open-chest dogs under pharmacological blockade autonomic nerve activity. An afterload change was imposed by clamping ascending or descending aorta to make peak LV early late systole. During interventions, contractions with...

A high resolution laser Doppler velocimeter using an optical fiber was developed to evaluate detailed characteristics of phasic blood flow in the coronary artery. Local velocities were measured proximal (0.27 ± 0.05 cm i.d.) and distal portion (0.09 0.02 left circumflex artery anesthetized, open-chest dogs. The velocity waveform central axial region vessel profile across vascular lumen compared portions.

Characteristics of blood-flow velocities were investigated at different sites in two types coronary artery bypass grafts, sequential saphenous vein grafts (SSVG) and internal mammary (IMAG). The latter appear to have the longest life span. patency rate side-to-side anastomosis SSVG is better than that end-to-side anastomosis. was anastomosed major diagonal branch by left anterior descending (LAD) 13 patients who had 75-100% 75-90% stenoses LAD branch, respectively. IMAG anastomoses performed...

In order to evaluate the functional characteristics of intramyocardial capacitance vessels during prolonged diastole, we analyzed response coronary vein flow after stepwise changes artery pressure in anesthetized open-chest dogs by using our newly developed laser Doppler velocimeter with an optical fiber. The peripheral portion great cardiac was isolated and fiber tip inserted into vessel. left anterior descending cannulated connected a reservoir regulate perfusion pressure. Intracoronary...

Underwater adhesive materials are in high demand various fields, and fish species with sucker disks have attracted attention due to their superior performance interesting structures. The clingfish, particular, is widely known for using hierarchical disk structures demonstrate rapid strong adhesion rocky surfaces under currents. We examined the combination of nanofilaments mucus clingfish disk. Nanofilaments reinforce force by reducing compliance without affecting contact area. prepared from...

Objective: The aim was to investigate the phasic characteristics of normal human left coronary artery flow and velocity profiles across vessel. Methods: in anterior descending artery, centreline velocities, were measured 10 patients during corrective surgery for atrial septal defect after closure defect. None these had any detectable stenosis or ventricular hypertrophy. Measurements made with a 20 MHz 80 channel pulsed Doppler velocimeter. Results: waveform displayed diastolic-predominant...

Ni anisotropic microgroove structures were prepared by lithographic processes and electroforming to investigate the effect of microstructures on friction forces. For structures, forces varied significantly depending indenter sliding direction microstructures. The parallel directions unstable considerably larger than those perpendicular owing difference in structure continuousness. These results suggest that affect can deploy fail-safe functions when a large load is accidentally applied.

The goal of this study was to evaluate microheterogeneity myocardial blood flow and its dependence on arterial O2 tension (PaO2). We measured within-layer distribution regional flows in the left ventricles anesthetized rabbits both normoxic hypoxic states with region sizes range 0.01-1.0 mm2. A novel method digital radiography combined technique 3H-labeled desmethylimipramine deposition enabled us visualize accurately quantitate at such high levels resolution. To analyze patterns, we...

BACKGROUND Nitroglycerin is effective in relieving myocardial ischemia; however, intracoronary nitroglycerin often fails to relieve angina and has been reported have deleterious effects on subendocardial blood flow. To understand the mechanisms involved, we evaluated direct effect of coronary circulation ischemic hearts. METHODS AND RESULTS We measured phasic pattern intramyocardial arterial flow with an 80-channel, 20-MHz pulsed Doppler ultrasound flowmeter under moderate severe artery...

In the present study, we attempted to test hypothesis that ejection timing rather than peak left ventricular pressure is a primary determinant of relaxation rate. cross-circulated isolated canine hearts instantaneous volume was controlled by servo-pump system. To eliminate effects end-systolic and end-diastolic volumes velocity on rate, these parameters were clamped, only (onset end ejection) altered, keeping duration unchanged. Left rate assessed time constants decline during isovolumic...

Using a needle-probe videomicroscope with charge-coupled device (CCD) camera, we measured the diameter of subendocardial arterioles and venules during prolonged diastole beyond time point at which coronary blood flow reached zero. In seven open-chest heart-blocked dogs, sheathed needle probe doughnut-shaped balloon was introduced from left atrial appendage advanced into ventricle through mitral valve. The tip placed gently on endocardial surface. Diameters (n = 16) beginning long ranged 40...

To analyze the effect of coronary stenosis on phasic pattern blood flow velocity into myocardium, we measured septal artery velocities under control conditions, i.e., no (N), with moderate (S1) and severe (S2) proximal arterial stenosis, during complete occlusion. In eight anesthetized open-chest dogs, measurements were performed using our 20-MHz multichannel pulsed Doppler method before after intracoronary adenosine administration. Under N, perfusion pressure was set to approximately 100...

To clarify the characteristics of phasic blood velocity pattern in small arteries and veins on left atrial surface, we used our newly developed fiber-optic laser Doppler velocimeter. We intended particularly to examine influence contraction relaxation waveforms obtain some insight into nature mechanical force acting intramyocardial vascular beds. In 14 anesthetized open-chest dogs, appendage was gently displaced expose branches artery vein. Vessels with an outer diameter about 150-500...

Using a 20-MHz 80-channel pulsed Doppler velocimeter and 30-MHz high-resolution echo ultrasound, we investigated the in vivo hemodynamics at origin of renal artery by measuring velocity profiles bifurcation geometry surgically exposed left 10 anesthetized dogs. The angle between aorta ranged from 60 degrees to 90 (mean, 84 degrees) although did not lie single anterodorsal plane diameter 1.5 3.5 mm 2.4 mm). Despite different geometries, aortorenal bifurcations were similar. Although regions...

In-vivo velocity profiles were recorded with a 20 MHz, 80-channel pulsed Doppler ultrasound velocimeter in canine end-to-side ilio-femoral anastomotic grafts. The geometries obtained from casts of the region, and flow rates measured electromagnetic probes. Three cases reported here include “standard” geometry, which was similar to previously studied vitro models, stenosed case below average rate. Observed features separation at hood toe, movement floor stagnation point, skewed proximal...

As local variations in blood flow are implicated atherogenesis at bifurcations, we measured vivo velocities different planes within exposed iliofemoral arterial bifurcations 8 dogs using 20-MHz, 80-channel Doppler ultrasound velocimetry. Cardiac frequency was fixed 2 Hz by pacing. Local geometry characterized 25-MHz, B-mode images, photographs, and methacrylate casts. The were asymmetrical planar to 5 degrees, the diameter ratios of daughter vessels ranged from 1.47 2.00, angles between them...

Vulcanized rubber is widely used in a wide range of applications because its flexibility, durability, sealing properties, and high degree friction. However, this friction can also become an issue, as it leads to the wearing breakage parts. In report, we investigated effects vulcanized microstructures on force by using simple, anisotropic microstructures. The line space master were prepared from photoresist, structures transferred PDMS, PSt, then Ni. After surface modification Ni TEOS,...

We examined the effect of nitroglycerin (NTG) on diameter and diastolic-to-systolic pulsation amplitude large (ID > 100 microns) small < subendocardial arterioles with their segmental responses. In 10 open-chest, anesthetized pigs, beating hearts (n = 18) were videorecorded using a needle-probe videomicroscope. Subendocardial arteriolar was determined before 1-2 min after NTG administration (25 micrograms/kg i.v.). an additional experiment three we monitored transient response 5) from...

The relation between the site and severity of coronary artery lesion infarct size was investigated in 59 patients with acute myocardial infarction. All had no prior infarction at least one significant narrowing (greater than or equal to 75%) major arteries first diagonal branch. Left ventriculography selective arteriography were performed on average 2.2 months after onset identify assess extent non-contracting segment (akinetic, dyskinetic, aneurysmal). Thirty-four studied enzymatically...

The influence of the filling condition unstressed volume (UV) intramyocardial vessels on diastolic coronary arterial pressure-flow relationship was analyzed. UV is defined as blood at zero transmural pressure. In seven anesthetized, paced dogs with induced heart block, artery inflow occluded so that in displaced into vein by myocardial contraction. After pacing turned off, perfusion pressure increased stepwise to target pressures (20-90 mmHg). reperfusion, left anterior descending (LAD) flow...

To obtain a smaller sample volume and suitable position for the measurement of blood velocity, we fabricated laser Doppler velocimeter (LDV) with dual-fiber pickup. The two fibers (clad: 62.5 micron core: 50 micron) were placed side by side. An He-Ne was introduced into through one fiber backscattered light collected other fiber. signal analyzed spectrum analyzer. shift frequency showed sharp peaked pattern both forward reverse flows exhibited an excellent correlation known velocity....