Kohji Kimura

Coronary Artery Dilatation Exceeding 4.0 mm During Acute Kawasaki Disease Predicts a High Probability of Subsequent Late Intima-Medial Thickening

We used intravascular ultrasound (IVUS) to compare the degree of coronary artery dilatation during the acute phase of Kawasaki disease with the extent of intima-medial thickening more than 10 years later. We wanted to determine if there was a threshold degree of dilatation that was highly predictive of later thickening. Twenty-eight patients with a mean age of 17.3 ± 1.7 years were studied; the mean interval from the initial selective coronary angiography to the IVUS study was 15.0 ± 1.6 years. We measured the maximum intima-medial thickness of selected coronary arterial segments in IVUS images and measured the largest diameters of the corresponding coronary arterial segments in the initial coronary angiograms. A significant correlation was found between the initial diameters of the coronary arteries and the intima-medial thickness more than 10 years later in the right coronary, the left anterior descending coronary, and the left circumflex arteries. The coefficient of correlation was 0.77 (n = 120, p < 0.0001), and for the bifurcation of the left coronary artery it was 0.50 (n = 26, p < 0.01). For this study, abnormal intima-medial thickness was defined as more than 0.40 mm. When the initial coronary arterial dilatation exceeded 4.0 mm, the sensitivity was 28/31 (90%) and the specificity was 87/89 (98%) in the right coronary, the left anterior descending coronary, and the left circumflex arteries. For the bifurcation of the left coronary artery, the sensitivity was 14/21 (67%) and the specificity was 5/5 (100%).

Improvement in mitral flow dynamics during exercise after percutaneous transvenous mitral commissurotomy. Noninvasive evaluation using continuous wave Doppler technique.

Evaluation of mitral flow dynamics during exercise is critically important in patients who receive percutaneous transvenous mitral commissurotomy (PTMC) because limited mitral flow during exercise provokes hemodynamic deterioration and involves cardiogenic symptoms in patients with mitral stenosis. To examine mitral flow dynamics during exercise, we applied continuous wave Doppler technique in 20 patients with mitral stenosis. Exercise Doppler study was performed 2 days before and 5 days after PTMC. PTMC increased mitral valve area from 1.0 +/- 0.3 (mean +/- SD) to 1.9 +/- 0.5 cm2 and decreased mean transmitral pressure gradient from 8 +/- 2 to 4 +/- 1 mm Hg at rest. Moreover, PTMC decreased mean transmitral pressure gradient from 21 +/- 6 to 11 +/- 4 mm Hg at submaximal exercise. The extent of an increase in mitral valve area by PTMC correlated with a decrease in the mean transmitral pressure gradient at the submaximal exercise (r = -0.76, p less than 0.01) and that at rest (r = -0.52, p less than 0.05). Heart rate after PTMC during exercise was significantly lower than that before PTMC, indicating that the compensatory mechanism (tachycardia) to increase cardiac output during exercise is less necessary after PTMC. Thus, we conclude that the mitral flow dynamics during exercise is improved, as well as the resting mitral flow dynamics 5 days after PTMC, and that exercise Doppler study enabled us to make a noninvasive evaluation of the mitral flow dynamics in patients who receive PTMC.

Rapid reduction of plasma atrial natriuretic peptide levels during percutaneous transvenous mitral commissurotomy in patients with mitral stenosis.

To clarify the direct contribution of the left atrial pressure to secretion of human atrial natriuretic peptide (hANP), we have attempted to study the relations between plasma hANP levels, neurohumoral factors, and hemodynamic changes in 13 patients with mitral stenosis undergoing percutaneous transvenous mitral commissurotomy (PTMC). After PTMC, the left atrial pressure fell from 14.7 +/- 1.9 (mean +/- SEM) to 6.5 +/- 0.7 mm Hg in all patients studied (p less than 0.0005), whereas there were no remarkable changes in either the right atrial pressure, mean arterial pressure, or heart rate. Plasma immunoreactive hANP levels obtained from the pulmonary artery decreased from 278 +/- 51 to 137 +/- 31 pg/ml after PTMC (p less than 0.0005). There was a significant correlation between the decrement of hANP levels and that of left atrial pressure (r = 0.72, p less than 0.005). Neither plasma renin activity nor norepinephrine levels changed. In contrast, plasma aldosterone concentrations significantly increased from 11.3 +/- 1.5 to 16.4 +/- 2.7 pg/ml after PTMC (p less than 0.01), although there was no casual relation between plasma concentrations of aldosterone and hANP. The present result with PTMC-induced rapid fall of the left atrial pressure with a concomitant reduction in hANP secretion strongly suggests the importance of the left atrial pressure on hANP secretion in humans.

A Pitfall in Ultrafast CT Scanning for the Detection of Left Atrial Thrombi

We studied 41 patients with mitral stenosis by ultrafast CT (UFCT) and transesophageal echocardiography to detect left atrial thrombi. Cardiac UFCT was performed twice after contrast medium injection to obtain early (during injection lasting 40-60 s) and late (approximately 5 min after beginning injection) phase images. There were 10 patients (24%) in whom a filling defect detected in the early phase disappeared in the late phase. The site of filling defects was the left atrial appendage in nine patients and the left atrium in one patient. All of the filling defects were in the ventral side of the left atrium. Furthermore, all of those patients had chronic atrial fibrillation. Transesophageal echocardiography revealed no thrombus in the area of the filling defect in the early phase. We believe that blood stasis existed in those patients. This finding leads to a false-positive result when only early phase images are obtained. The diagnosis of thrombi should be made only when a filling defect is observed in both phases. Late phase scanning is necessary in the diagnosis of left atrial thrombi.

Coronary artery anomalies with a shunt : Evaluation with electron-beam CT

PURPOSE Our goal was to evaluate the role of electron-beam CT (EBT) in the diagnosis of patients with coronary artery anomalies with a shunt. METHOD We performed EBT in seven patients with coronary artery anomalies with a shunt. Four cases were coronary artery fistula (CAF) and three were an anomalous origin of the left coronary artery from the pulmonary artery (ALCA from PA). Serial single volume mode scanning was performed at end-diastole to evaluate the anatomical course of the anomalous coronary arteries. Cine mode scanning was done in all but one to examine the ventricular wall motion and volumetrics. RESULTS EBT could detect the course and drainage sites of all CAFs and ALCAs from PA. Cine mode scanning revealed reduced wall motion in one case with CAF and two cases with ALCA from PA. CONCLUSION EBT serves a useful role in the assessment of coronary artery anomalies with a shunt.

Direct secretion from left atrium and pulmonary extraction of human atrial natriuretic peptide

To evaluate direct secretion from the left atrium and pulmonary extraction of human atrial natriuretic peptide (hANP), we measured plasma hANP levels in the pulmonary artery, pulmonary vein, and left atrium in patients with either mitral stenosis or atrial septal defect. Left atrial pressure in patients with mitral stenosis was significantly higher than that in patients with atrial septal defect (7.5 +/- 1.0 mm Hg vs 3.1 +/- 0.5 mm Hg, p less than 0.01). The significant increase in the hANP level in the left atrium was recognized only in patients with mitral stenosis (149 +/- 33 pg/ml in the left atrium vs 130 +/- 28 pg/ml in the pulmonary vein, p less than 0.05). The plasma hANP level in the pulmonary vein was significantly lower than that in the pulmonary artery in both patients with mitral stenosis and those with atrial septal defect, which suggests that hANP is extracted in the lung. We conclude that hANP is secreted not only through the coronary sinus but also directly from the left atrium, stimulated by high left atrial pressure, and that circulating hANP is partially extracted in the pulmonary circulation.

Left ventricular diastolic pressure-volume response immediately after successful percutaneous transvenous mitral commissurotomy

The left ventricular (LV) diastolic pressure-volume response after percutaneous transvenous mitral commissurotomy (PTMC) was investigated to determine whether it was related to the baseline conditions of the left ventricle. Left ventriculography was performed, and the measurements of LV pressure were obtained in 32 patients before and after PTMC. Mitral valve area increased from 1.0 +/- 0.3 to 1.9 +/- 0.4 cm2 (p < 0.005) after PTMC, which caused a decrease in left atrial mean pressure (14.8 +/- 5.9 to 7.4 +/- 2.7 mm Hg; p < 0.005). LV end-diastolic pressure increased in all patients 5 minutes after PTMC. However, patients could be divided into 2 groups according to the following changes in LV end-diastolic pressure 20 minutes after PTMC: In 22 patients, LV end-diastolic pressure returned to the near-baseline level 20 minutes after PTMC (before 5.0 +/- 2.2, 5 minutes after 8.6 +/- 3.1, and 20 minutes after 6.3 +/- 2.5 mm Hg) with a significant increase in LV end-diastolic volume index (64 +/- 12 to 74 +/- 14 ml/m2; p < 0.001) and augmentation of LV stroke volume index (39 +/- 9 to 47 +/- 11 ml/m2; p < 0.001). However, in the remaining 10 patients with a larger LV volume (> 80 ml/m2) and reduced ejection fraction (< 50%) at baseline, LV end-diastolic pressure further increased 20 minutes after PTMC (before 5.5 +/- 2.8, 5 minutes after 7.8 +/- 2.7, and 20 minutes after 11.0 +/- 2.9 mm Hg) without significant changes in LV volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential goals for the dimensions of the pulmonary arteries and aorta with stenting after the Fontan operation

The purpose of this study was to clarify desired stent sizes for stenotic lesions in the post‐Fontan circulation. Using angiograms from 22 patients before and at late follow‐up (≥ 15 years) after the Fontan operation, we measured the maximum diameters of the proximal pulmonary arteries (PA) and the descending aorta. The diameters of the PA ipsilateral to the inferior vena cava, contralateral to the inferior vena cava, and descending aorta after the Fontan were 10.6–22.6 (15.8 ± 3.3), 8.0–19.1 (12.9 ± 3.1), and 12.1–18.9 (15.8 ± 2.0) mm, respectively, while the percent of normal predicted diameters (% N) were 55%–104% (70% ± 14%), 38%–99% (66% ± 17%), and 46%–74% (60% ± 7%), respectively. Despite somatic growth, the % N of all vessel diameters decreased significantly after the Fontan operation. In conclusion, smaller‐sized stents should be acceptable for both the pulmonary artery and descending aorta in the Fontan circulation. Cathet Cardiovasc Intervent 2002;56:246–253.

Late neointimal proliferation following implantation of stents for relief of pulmonary arterial stenosis.

On the assumption that the diameter of the reference vessel might determine the thickness of neointimal coverage of stents placed in the pulmonary arteries, we analyzed the angiograms of 28 lesions in 17 patients who underwent follow-up cardiac catheterization. Excluding 2 lesions where late stenosis was determined mainly by recoil of greater than 30%, we investigated the neointimal thickness of 26 lesions in 16 patients. Several factors that might contribute to late re-stenosis were also analyzed. Age and body weight at implantation ranged from 0.8 to 20 years, with a median of 6 years, and from 6.8 to 77.5 kg, with a median of 17.6 kg. Follow-up interval was from 6 to 15 months, with a median of 6 months. There was a significant increase in diameter, as well as a reduction in pressure gradient, immediately after the implantation of stents. Although there was no significant difference between the achieved diameter and the diameter of the stent at follow-up, the diameter of the lesion at follow-up was significantly smaller than the diameter achieved by stenting. The increase in the pressure gradient at follow-up was slightly greater in 4 lesions where the late reduction in diameter was greater than 30% than in the 18 lesions where this was less than 30% (p = 0.05). The diameter of the reference vessel, and the diameter by stenting correlated with the late reduction in diameter. All lesions with diameter reduced greater than 30% had a reference diameter of less than 6.1 mm, and a diameter achieved by stenting of less than 6.5 mm. Late loss in luminal diameter directly correlated with the thickness of the neointimal coverage. In conclusion, close observation should be mandatory following implantation of stents in small pulmonary arteries.

Late distortion of the original Palmaz stent implanted in postoperative lesions associated with congenital heart disease

The objective of this study was to report late distortion of a Palmaz stent. Late distortion of an original Palmaz stent, implanted in an extracardiac lesion, is rare. We completed a 1‐year follow‐up of 54 patients who had been implanted with 80 Palmaz stents in extracardiac lesions. Distortion of two stents was detected in two patients. For case 1, we implanted a P188 stent for supravalvar pulmonary stenosis complicating an arterial switch operation in a 14‐year‐old girl. Seven months later, we found compression of the stent. Although we implanted two P308 stents anterior to the distorted stent, distortion of both stents developed after 1 month. Two more P308 stents placed inside each stent were gradually recompressed. A CAT scan showed compression of the stent by a dilated sinus of valsalva. For case 2, we implanted a P308 stent for stenosis of the superior vena cava after Williams operation in an 11‐year‐old boy. A chest X‐ray documented longitudinal compression of the stent 27 months after implantation and a CAT scan showed the ascending aorta was in contact with the stent. A Palmaz stent may be distorted when implanted in a lesion adjacent to a pulsating aorta.