Shigeru Eiho

Changes in diastolic properties of the regional myocardium during pacing-induced ischemia in human subjects.

Mechanisms related to alterations in the diastolic properties of the left ventricle during angina were studied in seven patients with coronary artery disease. Single plane left ventriculograms were obtained using a high fidelity micromanometer-tipped catheter in both the resting state and immediately after rapid cardiac pacing. In all patients, typical anginal pain developed with pacing stress. After atrial pacing, the left ventricular end-diastolic pressure increased from 10 +/- 3 to 21 +/- 7 mm Hg (+/- standard deviation) (p less than 0.005) regardless of the changes in the end-diastolic volume. The ejection fraction was reduced from 59 +/- 10 to 48 +/- 13% (p less than 0.05). The diastolic pressure-volume curves shifted upward in post-pacing beats in four patients, while in three the curves shifted more to the right. The regional myocardial function was expressed in quantitative terms by a radial coordinate system with the origin at the center of gravity of the end-diastolic silhouette. Two representative radial grids for normal and ischemic segments were selected. In the normal segment, the end-diastolic length was augmented by 15% (p less than 0.005) and was associated with a 24% increase in stroke excursion with pacing stress (p less than 0.05). The increase in diastolic pressure was accompanied by comparable increases in end-diastolic length, and the diastolic pressure-length relation moved up to the higher portion of the single curve. In the ischemic segment, the end-diastolic length remained unchanged in the post-pacing beat, but segment shortening was significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of posture on cardiac autonomic nervous activity in patients with congestive heart failure.

OBJECTIVES We aimed to clarify which recumbent position is preferred by patients with congestive heart failure (CHF) and to evaluate whether cardiac autonomic nervous activity is different among three recumbent positions (supine, left lateral decubitus, right lateral decubitus) in patients with CHF. BACKGROUND It remains unclear whether cardiac autonomic nervous activity is different among three recumbent positions in patients with CHF. METHODS We studied 17 male CHF patients (66+/-7 years) and 17 age- and gender-matched healthy subjects (66+/-7 years). Each subject underwent 24-h ambulatory electrocardiographic monitoring. A channel was used to record the CM5 lead, and another to record the signal of the patients posture with use of a newly developed small-sized detector (3.2 cm x 3.2 cm). By using spectral analysis of heart rate variability, frequency-domain measures were calculated and compared among the three recumbent positions. Normalized high-frequency (HF: 0.15 to 0.40 Hz) power was used as an index of vagal activity and the low frequency (0.04 to 0.15 Hz)/HF power ratio was used as an index of sympathovagal balance. RESULTS In patients with CHF, the time for the right lateral decubitus position was two-fold longer than that for the supine and left lateral decubitus positions. The increased cardiac sympathetic activity and decreased vagal tone in CHF patients were normalized in the right lateral decubitus position. CONCLUSIONS The right lateral decubitus position in patients with CHF may be a self-protecting mechanism of attenuating the imbalance of cardiac autonomic nervous activity.

Detection of coronary artery tree using morphological operator

Presents a technique of the automatic detection of the coronary artery tree on the coronary cineangiogram. The method uses several kinds of morphological operations. The morphological Top-Hat operator is used for enhancing the shape of the artery. The morphological erosion and the half-thresholding are used for removing points except the coronary area. Then one can extract the entire coronary artery tree on the angiogram after pointing at just one point on the coronary artery. The extracted coronary parts are skeletonized by the thinning operation. Finally the morphological watershed transformation is done by using the skeleton and the dilated binary image of the coronary. As a result, a clear boundary of the coronary artery is obtainable automatically. Some experimental studies confirm the ease and correctness of the detection of the coronary artery boundary by the method proposed.

Effects of posture on sympathetic nervous modulation in patients with chronic heart failure

We investigated which recumbent position is preferred by patients with chronic heart failure (CHF) and whether sympathetic nervous modulation differs in three recumbent positions. We assessed 12 patients with CHF by spectral analysis of heart-rate variability and measurement of plasma norepinephrine concentrations. The right lateral decubitus position was preferred for significantly longer periods than the left lateral decubitus and supine positions. Sympathetic nervous modulation was most attenuated in the right lateral decubitus position. The right lateral decubitus position preferred by patients with CHF may be a self-protective mechanism to control increased sympathetic nervous modulation.

Automated method for left ventricular volume measurement by cineventriculography with minimal doses of contrast medium

Cineventriculography is of considerable value in the dimensional analysis of the left ventricular cavity, but conventional methods necessitate injection of large amounts of contrast medium. In this study, small dose left ventriculography, using only 5 ml of dye, was performed in order to minimize the untoward effects of contrast medium. A computer-aided image processing system was also developed to enhance the contrast of the ventricular image by subtracting the reference image to eliminate irrelevant background. The boundary of the left ventricular cavity was automatically determined to calculate the instantaneous volume change throughout the cardiac cycle. With use of this small dose of dye, the elevation of left ventricular end-diastolic pressure that consistently occurred 1 to 3 minutes after injection of conventional large doses could be avoided. (End-diastolic pressure at 1 minute after dye injection averaged 11.8 +/- 4.9 [mean +/- standard deviation] for small dose and 19.1 +/- 6.1 mm Hg for large dose injection.) Values for end-diastolic volume, end-systolic volume and ejection fraction calculated from the two consecutive small and large dose left ventriculograms in 16 patients were similar. Thus, minimal doses of contrast medium permit accurate measurement of left ventricular dimension and function without significant hemodynamic derangement. The optimal projection for regional wall motion analysis can easily be selected by this method with repeated exposure at various degrees of obliquity. With this technique, even noninvasive measurement of left ventricular volume can be provided by intravenous injection of small doses of contrast agent.

Analysis of asynchronous wall motion by regional pressure-length loops in patients with coronary artery disease.

The progression of regional dysfunction during angina pectoris was studied in eight patients with coronary artery disease. Single plane left ventriculograms were obtained using a high fidelity micromanometer-tipped catheter both at rest and immediately after rapid cardiac pacing. Each image of the left ventriculogram was digitized and transferred to a computer. The boundary of the ventricular cavity was automatically determined and sequentially superimposed. Regional shortening was quantified by a radial coordinate system originating at the center of gravity of the end-diastolic silhouette. Thirty-two radial grids were drawn around the center of gravity, and the length of each radial grid was measured to characterize the centripetal motion of a given surface point. Each radial length was then plotted simultaneously and continuously against left ventricular pressure to generate a pressure-length loop. The area of the pressure-length loop provided an index of regional myocardial work. In the ischemic ventricle, the loops exhibited a striking deformity in configuration. Prolonged relaxation of ischemic segments was associated with outward motion of the normal segments. Shortening of the normal segment occurred earlier than that of the ischemic segment associated with its stretch. Thus, the loops of the two areas inclined in opposite directions. Pacing stress increased the magnitude of hypofunction in the potentially ischemic area, the average extent of shortening being reduced by 30% and the segmental work by 25% (p less than 0.005). In the normal area, contrary to the significant increase in segmental shortening (20% above control values [p less than 0.005]), the average segmental work remained at 7% below control values because of an augmented deformation of the loop.(ABSTRACT TRUNCATED AT 250 WORDS)

3-D heart image reconstructed from MRI data

The gated MRI method gives us several sets of cross-sectional images on transverse, coronal, and sagittal planes of the heart in a cardiac cycle. In this paper, a method to reconstruct 3-D shapes of each part of the heart (i.e., left ventricle, left atrium, right ventricle, right atrium, aorta, and pulmonary artery), in a voxel space using these sets of cross-sectional images is proposed. The whole heart image composed of these six parts properly put together can be superimposed on the original cross-sectional images for display purposes.

Preoperative and intraoperative image processing for assisting endovascular stent grafting

Recent development in interventional radiology enables minimally invasive treatment of aortic aneurysm: endovascular stent grafting. We report image processing method in preoperative planning and intraoperative guidance for assisting endovascular stent grafting. In preoperative planning, it is necessary to design stent graft suitable for each clinical case. Thus we present shape measurement method of aneurysmal aorta for computer assisted design of stent graft. In stent grafting, fluoroscopic image is used as intraoperative image for visualizing lesion and interventional device. As fluoroscopic image is a two-dimensional (2D) image, a doctor has to imagine three-dimensional (3D) shape of aneurysmal aorta. For intraoperative guidance, it is useful to register preoperative 3D CT image with intraoperative 2D fluoroscopic images. We present intraoperative 3D/2D registration method for assisting endovascular stent grafting and show application result to clinical data.

Circadian variation of cardiac autonomic nervous activity is well preserved in patients with mild to moderate chronic heart failure: effect of patient position

BACKGROUND It remains unclear whether circadian variation (CV) of cardiac autonomic nervous activity (CANA) is preserved in patients with chronic heart failure (CHF) as in healthy subjects. We have demonstrated that CANA in CHF patients is largely affected by patient recumbent position. METHODS We studied eight mild to moderate CHF patients and eight age, sex-matched healthy subjects. Each subject underwent 24-h ambulatory ECG monitoring. One channel was used to record the CM5 lead, and another to record the signal of patient position from a newly developed, small-sized detector. By using spectral analysis of heart rate variability, frequency-domain measures were calculated. Normalized high-frequency (HF: 0.15-0.40 Hz) power was used as an index of vagal activity and the low frequency (LF: 0.04-0.15 Hz)/HF power ratio was used as an index of sympathovagal balance. These indexes in the same recumbent position were compared between night (2:00-4:00 a.m.) and morning (6:00-8:00 a.m.). RESULTS In healthy subjects, a definite CV of CANA was observed in each recumbent position. In patients with CHF, in each position, normalized HF power was lower in the morning than at night, whereas LF/HF was higher in the morning than at night. Thus, CANA in CHF patients is influenced not only by patient position but also by the time of day. CONCLUSION CV of CANA in mild to moderate CHF patients is well preserved when taking patient position into consideration.

Automatic detection of the coronary arterial contours with sub-branches from an X-ray angiogram

Describes a method to trace the coronary arterial boundaries with branches automatically from X-ray angiograms. The edge points are fixed by a function based on smoothing differential operator for the gray values on the searching line defined from the edge points fixed previously. Thus the boundary points along the artery are detected automatically. The branch positions are detected automatically and the branch of the artery is searched by the same algorithm. In the edge detection process, the required user interaction is only the manual pointing of the initial data such as the starting point the direction and the range for search. This method is tested and verified its usefulness through computer generated images with different stenoses and actual angiograms.<<ETX>>