Makoto Takamiya

Plasma Brain Natriuretic Peptide Levels Increase in Proportion to the Extent of Right Ventricular Dysfunction in Pulmonary Hypertension

OBJECTIVES This study sought to investigate the influence of right ventricular (RV) hemodynamic variables and function on the secretion of brain natriuretic peptide (BNP) in patients with isolated RV overload. BACKGROUND Plasma BNP is known to increase in proportion to the degree of left ventricular (LV) overload. However, whether BNP secretion is also regulated in the presence of RV overload remains unknown. METHODS Plasma BNP and atrial natriuretic peptide (ANP) levels in the pulmonary artery were measured in 44 patients with RV overload: 18 with RV volume overload (RVVO) due to atrial septal defect and 26 with RV pressure overload (RVPO) due to primary or thromboembolic pulmonary hypertension. Right heart catheterization was performed in all patients. RV and LV ejection fraction, myocardial mass and volume of the four chambers were determined by using electron beam computed tomography. RESULTS Although both plasma BNP and ANP levels were significantly elevated in patients with RV overload compared with values in control subjects, plasma BNP and the BNP/ANP ratio were significantly higher in patients with RVPO than with RVVO (BNP 294 +/- 72 vs. 48 +/- 14 pg/ml; BNP/ANP 1.6 +/- 0.2 vs. 0.8 +/- 0.2, both p < 0.05). Plasma BNP correlated positively with mean pulmonary artery pressure (r = 0.73), total pulmonary resistance (r = 0.79), mean right atrial pressure (r = 0.79), RV end-diastolic pressure (r = 0.76) and RV myocardial mass (r = 0.71); it correlated negatively with cardiac output (r = -0.33) and RV ejection fraction (r = -0.71). Plasma BNP significantly decreased from 315 +/- 120 to 144 +/- 54 pg/ml with long-term vasodilator therapy (total pulmonary resistance decreased from 23 +/- 4 to 15 +/- 3 Wood U). CONCLUSIONS Plasma BNP increases in proportion to the extent of RV dysfunction in pulmonary hypertension.

Coronary arterial lesions of Kawasaki disease: cardiac catheterization findings of 1100 cases.

SummaryIn our institute, 1100 patients with a history of Kawasaki disease have been catheterized for selective coronary arteriography. Their age at examination ranged from four months to 13 years. Coronary artery lesions (CAL) were found in 262 patients. As far as the type of the CAL was concerned, occlusion was noted in 20 (7.6%), segmental stenosis in 15 (5.7%), localized stenosis in 62 (23.7%), aneurysm in 93 (35.5%), and dilatation in 72 patients (27.5%). In terms of the total number of lesions, there were 23 occlusions, 19 segmental stenoses, 109 localized stenoses, 449 aneurysms and 307 dilatations.The 262 patients with CAL were analyzed according to the interval from the onset to the time of selective coronary arteriography. The incidence of both occlusion and segmental stenosis was lowest in the group who were catheterized shortly after the onset of disease, whereas the prevalence of aneurysm was highest in this group. But the prevalence of dilatation was highest in the group of patients who were catheterized late. A total of 12 patients had to undergo femoral arterial thrombectomy for arterial thrombosis following the catheterization, but no other major complication was experienced.

MRA of the Adamkiewicz artery: a preoperative study for thoracic aortic aneurysm.

PURPOSE The purpose of this work was to investigate the ability of MR angiography (MRA) to visualize the Adamkiewicz artery (AKA) as a preoperative study of thoracic aortic aneurysm to prevent ischemic injury of the spinal cord. METHOD Twenty-six patients scheduled for surgical or endovascular stent-graft repair of thoracic aortic aneurysm were studied with a three-dimensional contrast MRA. Data acquisition was repeated two times following injection of Gd-DTPA. Source images were processed with multiplanar reconstruction and maximum intensity projection. RESULTS The AKA was identified in 69% (18/26). In three patients, selective angiography of the intercostal artery confirmed the AKA at the same level and side predicted by MRA. The anterior spinal artery and the anterior medullary vein were observed in 50% (13/26) and 65% (17/26), respectively. CONCLUSION Contrast MRA is a promising technique to visualize the AKA noninvasively as a preoperative evaluation of thoracic aortic aneurysms.

Preoperative demonstration of the Adamkiewicz artery by magnetic resonance angiography in patients with descending or thoracoabdominal aortic aneurysms

OBJECTIVE Investigating the possibility of magnetic resonance angiography (MRA) to visualize the Adamkiewicz artery of as a preoperative study of thoracic aortic aneurysms. METHODS From February 1998 to March 1999, 26 consecutive patients who had aneurysms of the thoracoabdominal or descending aorta underwent preoperative MRA to visualize the Adamkiewicz artery. Mean age was 60.5+/-11.5 years. Fifteen patients had non-dissecting aneurysm and 11 had aortic dissections. Nineteen patients underwent replacement of the aneurysms, four patients underwent endovascular stent-graft repair, and three patients were discharged without treatment of aneurysm. MRA was performed on a 1.5-T system (Magnetom, Siemens) and data acquisition was repeated two times following injection of gadolinium-DTPA. Source images were reconstructed with multiplanar reconstruction and maximum intensity projection. Criteria for the Adamkiewicz artery of were that the artery ascends from the dorsal branch of the intercostal or lumbar artery to the anterior mid-sagital surface of the spinal cord in the early phase. RESULTS The Adamkiewicz arteries were demonstrated in 18 patients (69%). These arteries were originated from the left intercostal or lumbar arteries in 13 (72.2%) patients and from the right in 5 (27.8%) and from the Th8 branch in three, Th9 in seven, Th10 in two, Th11 in four, and L1 in two. All patients had graft replacement of the aorta using a partial bypass. All intercostal or lumber arteries, which were visualized as the origin of the Adamkiewicz artery, were reattached to the grafts. No spinal cord injury occurred. CONCLUSION Preoperative detection the Adamkiewicz artery was possible by MRA and was very useful to reduce the incidence of ischemic injury of the spinal cord during surgery of the thoracoabdominal or descending aorta.

Usefulness of Electron-Beam Computed Tomography in Arrhythmogenic Right Ventricular Dysplasia Relationship to Electrophysiological Abnormalities and Left Ventricular Involvement

BACKGROUND Electron-beam computed tomography (CT) may be useful for detecting myocardial fat infiltration and diagnosing arrhythmogenic right ventricular dysplasia (ARVD). There are several characteristic electron-beam CT findings of ARVD. However, the incidence, their relation to electrophysiological abnormalities, and the usefulness of electron-beam CT for evaluating left ventricular involvement are unknown. This study aimed to clarify these issues. METHODS AND RESULTS Electron-beam CT was performed in 14 patients with ARVD (ARVD group), 16 age- and sex-matched patients with right ventricular enlargement and/or dysfunction without ARVD (RV enlargement group), and 13 control subjects (control group). The incidences of abnormal electron-beam CT findings in the three groups were examined. Furthermore, we examined the endocardial fat-infiltrated areas detected by electron-beam CT (CT-A) and electrophysiologically abnormal areas detected in the mapping electrophysiology study (EPS-A) and compared the relationship between them in the ARVD group. (1) The frequencies of abundant epicardial adipose tissue, low-attenuation trabeculations, scalloping of the right ventricular free wall, and intramyocardial fat deposits were 86%, 71%, 79%, and 50%, respectively, in the ARVD group, whereas these findings were not observed in the RV enlargement and control groups. (2) Three ARVD patients (21%) had adipose tissue involvement of the left ventricle. (3) The relationship between CT-A and EPS-A was as follows: CT-A > EPS-A, 71%; CT-A = EPS-A, 14%; and EPS-A only, 14%. CONCLUSIONS Characteristic electron-beam CT findings are frequently observed only in patients with ARVD. Electron-beam CT is useful for evaluating for left ventricular involvement and can estimate EPS-A.

Sensitivity and specificity of CT in the diagnosis of inflammatory abdominal aortic aneurysms.

Purpose The purpose of this study is to assess the diagnostic ability (sensitivity and specificity) of CT in the diagnosis of inflammatory abdominal aortic aneurysm (IAAA) and to quantitatively evaluate its features. Method A retrospective survey of 355 consecutive patients with abdominal aortic aneurysm and iliac artery aneurysm who underwent CT examination and surgical repair yielded 18 patients with operatively confirmed IAAA. The sensitivity, specificity, and diagnostic accuracy of CT were evaluated in this review. Eighteen IAAAs were then analyzed in terms of distribution and degree of perianeurysmal fibrosis as well as time-dependent change of CT values of the aneurysmal wall on contrast-enhanced CT. Complications related to IAAA were also determined. Results Fifteen of the 18 cases of IAAA could be easily diagnosed on CT prior to surgical repair. Three false-negative and one false-positive case were found. This gives a sensitivity rate of 83.3% for this imaging technique, with specificity and accuracy rates of 99.7 and 93.7%, respectively. Thickening of the aortic wall was noticed mostly in the anterolateral wall of the aneurysm as compared with the posterior wall. The thickness of the perianeurysmal fibrosis correlated neither with the size of aneurysm nor with the inflammatory reaction such as erythrocyte sedimentation rate, C-reactive protein level, and white blood cell count. CT indicated the complications in 7 of 18 patients with IAAA. These included hydronephrosis, aortoenteric fistula, and infected iliac aneurysm. Conclusion CT scan with contrast enhancement was a highly reliable imaging modality for the diagnosis of IAAA.

Arrhythmogenic Right Ventricular Cardiomyopathy Underlies Syndrome of Right Bundle Branch Block, ST-Segment Elevation, and Sudden Death

Right ventricular morphologic and/or histologic abnormalities were present in 5 of 6 Japanese men with the Brugada syndrome. Results indicate that arrhythmogenic right ventricular cardiomyopathy may underlie the cardiac manifestations in the Brugada syndrome.

Critical Degree of Renal Arterial Stenosis That Causes Hypertension in Dogs

The minimum degree of renal arterial stenosis needed to cause hypertension was identified by renal arterial angiography of anesthetized dogs. The effects of renal nerves and prostanoids on the critical stenosis were also examined. The left renal artery was constricted concentrically by a radiolucent con strictor device, and the stenosis of the artery was evaluated by cineangiography with the kidney either innervated or denervated. At this time, renal blood flow, renal perfusion pressure, and systemic blood pressure were serially monitored. In another group of dogs, renal venous and aortic blood samples were taken as the stenosis increased; these were assayed for prostaglandin E2 and plasma re nin activity. The same experiments were done again after treatment with a cyclooxygenase inhibitor, aspirin DL-lysine (54 mg/kg). With the kidney either innervated or denervated, systemic blood pressure began to increase when the stenosis was more than 70% of the diameter of the renal artery; the renal blood flow decreased when the stenosis was more than 75% of the diameter. Aspirin treatment attenuated the increase in blood pres sure but did not affect the autoregulation of the renal blood flow when stenosis was 70% or less. Prostaglandin E2 production increased in the stenotic kidney when the stenosis was more than 70%; aspirin inhibited prostaglandin synthesis and suppressed the stimulation of renin release. These results suggest that whether there is innervation or not, the critical degree of renal arterial stenosis that causes hypertension is more than about 70% of the diameter in the presence of renal prostaglandins; in their absence, the critical point above which hypertension occurs is 75% or more.

Aspirin lowers blood pressure in patients with renovascular hypertension.

To clarify the role of renal prostanoid in hyperreninemia and high blood pressure in human renovascular hypertension, we measured prostaglandin E2 and renin activity in renal venous and abdominal aortic plasma before and after the intravenous administration of the cyclooxygenase inhibitor, aspirin DL-lysine. Subjects were six patients with unilateral renovascular hypertension and six with essential hypertension. In patients with renovascular hypertension, prostaglandin E2 concentration in renal venous plasma from the stenotic kidney was 9.25 ±1.48 pg/ml, which was significantly higher (p < 0.01) than the concentration in the renal venous plasma from the normal kidney (4.97±1.02 pg/ml) or in the aortic plasma (2.59±0.15 pg/ml). Plasma renin activity was also higher in the renal vein of the stenotic kidney than in the other two sites. The stenotic side/normal side ratio of the renal venous prostaglandin E2 correlated significantly with a renin ratio greater than 1.5 (r=0.8211, p < 0.05). Intravenous injection of aspirin DL-lysine (18 mg/kg) 30 minutes later markedly suppressed prostaglandin E2 and renin levels at all sites and clearly lowered arterial blood pressure (mean: from 120±6 to 110±5 mm Hg, p < 0.01). The reduction in blood pressure correlated significantly with the suppression of plasma renin activity in the aorta (p < 0.05) and in the renal vein of the stenotic kidney (p < 0.01). Conversely, in patients with essential hypertension, aspirin had little effect on renin levels and increased mean blood pressure. These data indicate that renal prostaglandin plays an important role in the augmented release of renal renin and the pathogenesis of hypertension in human renovascular hypertension.

Diagnostic Value of Plasma Levels of Brain Natriuretic Peptide in Arrhythmogenic Right Ventricular Dysplasia

BACKGROUND Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by local or diffuse wall motion abnormalities in the right ventricle (RV), associated with recurrent ventricular tachycardia (VT) of RV origin. Brain natriuretic peptide (BNP) was first isolated from a porcine brain extract. In humans, BNP is expressed predominantly in the ventricles of failing hearts, and its expression has been observed primarily in myocytes in the interstitial fibrous area in dilated cardiomyopathy. We hypothesized that BNP is increasingly secreted from the residual myocytes within the atrophic tissue in patients with ARVD. METHODS AND RESULTS Plasma BNP levels were measured in 17 patients with ARVD, 12 patients with idiopathic RV outflow tract tachycardia (RVOT), and 120 control subjects. We performed cardiac catheterization, RV endomyocardial biopsy, electron- beam CT, and biventricular endomyocardial mapping in the ARVD patients. There was a significant increase in plasma BNP levels in the ARVD patients compared with the RVOT patients and control subjects (61.4+/-59.6 pg/mL versus 8.3+/-5. 5 pg/mL and 9.3+/-5.8 pg/mL; P<0.0001, respectively). The plasma BNP levels had no correlation with any of the hemodynamic data, but they had a significant correlation with the RV ejection fraction (r=-0. 588, P=0.025) and with the fractionated-area scores (r=0.705, P=0. 005). Light microscopic immunohistochemistry showed strong BNP immunoreactivity in residual myocytes with fibrofatty replacement. CONCLUSIONS These results suggest that plasma BNP levels were not increased in RVOT patients but were increased in ARVD patients, and that the increased BNP levels indicate the severity of both the RV dysfunction and the arrhythmogenic substrate.