Takahisa Uchiyama

Diagnosis of anomalous origin of the right coronary artery using multislice computed tomography: evaluation of possible causes of myocardial ischemia.

Anomalous origin of the right coronary artery (RCA) is a rare condition, but may cause myocardial ischemia and sudden death. Multislice computed tomography, which allows three-dimensional visualization of the coronary artery with high spatial resolution, may be the most promising imaging modality for diagnosing this anomaly. We describe a patient with anomalous origin of the RCA arising from the left sinus of Valsalva. Volume rendering, and axial and curved multiplanar images showed stenosis in the proximal portion of the RCA that coursed between the aorta and the pulmonary artery, and an acute angled take-off of the RCA from the aorta. Three-dimensional virtual angioscopic images showed a hypoplastic RCA orifice and luminal narrowing in the proximal portion of the RCA. Multislice computed tomography was thought to be useful for detecting anomalous origin of the RCA and for evaluating possible causes of myocardial ischemia.

Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium

A 66-year-old woman was admitted to our hospital because of left ventricular failure and nonsustained ventricular tachycardia. Two-dimensional echocardiography demonstrated prominent trabeculations and deep intertrabecular recesses, findings consistent with noncompaction of the ventricular myocardium. Myocardial perfusion scintigraphy demonstrated a defect in the anterobasal left ventricular segment. Coronary angiogram was normal, but the left ventriculogram showed an aneurysm in the anterior myocardial segments. This is the first reported case with isolated noncompaction of the ventricular myocardium associated with left ventricular aneurysm.

Association of electrocardiographic abnormalities with seropositivity to Trypanosoma cruzi in Ecuador

In highland Ecuador (province of El Oro), electrocardiograms (ECGs) were taken and analysed from 340 subjects, of whom 154 were seropositive to Trypanosoma cruzi by indirect haemagglutination test. Abnormal ECGs were present in 40.3% of seropositive individuals and 8.1% of seronegatives, and were slightly more common in seropositive males than in seropositive females. In seropositive individuals, the prevalence of abnormal ECG progressively increased with age and reached its peak level of 64.0% in the age group over 60 years, implying that Chagas disease in Ecuador produces little mortality among seropositive individuals. The most common ECG alterations were ventricular conduction defects: 26 of 117 seropositive individuals in the age group over 40 years had complete right bundle branch block. The frequency of atrioventricular block and arrhythmias was also associated with seropositivity to T. cruzi. A further ECG examination in lowland (province of Guayas) showed that the prevalence of abnormal ECGs there was significantly lower than that in highlands. These results suggest possible differences between T. cruzi strains in the two geographical areas of Ecuador.

Effect of a high-salt diet on γ-aminobutyric acid-mediated responses in the nucleus tractus solitarius of Sprague–Dawley rats

Previous study using an indirect gamma-aminobutyric acid (GABA) agonist indicated that high salt intake enhances sensitivity of nucleus tractus solitarius (NTS) projecting inhibitory input to rostral ventrolateral medulla sympathoexcitatory neurons. We further investigated the relationship between salt intake and the GABA system in NTS. Sprague-Dawley (S-D) rats consuming high dietary salt (8%) or low dietary salt (0.3%) for 3 weeks were used. Under chloralose-anesthesia, baseline arterial pressure (AP) and heart rate (HR) were similar in both groups. Bilateral injection into NTS of nipecotic acid, GABA(A) receptor agonist (muscimol), or GABA(B) receptor agonist (baclofen) elicited greater pressor responses in high-salt group. GABA(A) receptor antagonist, bicuculline and GABA(B) receptor antagonist, CGP-35348 elicited greater depressor responses. Phenylephrine or nitroprusside (i.v.) elicited similar respective increases or decreases in AP in both groups. Baroreflex sensitivity was similar. Thus, high-salt intake enhances both GABA(A) receptor- and GABA(B) receptor-mediated responses within NTS, thereby inhibiting elevation of AP.

Multidetector computed tomography of a saphenous vein graft aneurysm.

A 64-year-old man with a history of hypercholesterolemia, smoking, arteriosclerosis obliterans, and aortocoronary bypass grafting (CABG) presented with an enlarging right cardiophrenic angle mass found on routine chest X-ray (Fig. 1). At the time of his CABG 14 years earlier, the left internal mammary artery was used to graft the left anterior descending artery and the saphenous vein graft (SVG) was placed to the right coronary artery. He had a long-standing history of hypercholesterolemia. Multidetector computed tomography (MDCT) was performed using an Aquillion 16 (16-detector-row, Toshiba Medical, Tokyo, Japan). The scan protocol and image reconstruction method have been reported previously. The reconstructed data were transferred to a computer workstation (M 900 quadra; AMIN, Tokyo, Japan) for processing of the surface volume rendering and multiplanar reformation images. The volumerendering images (Fig. 2A,B) showed an aneurysm of the saphenous vein graft with a thick, low attenuation suggesting a thrombus. The native right coronary artery was totally occluded. The SVG–right coronary artery and left internal mammary artery–left descending artery grafts were patent. The multiplanar reformation image also showed a markedly dilated SVG (Fig. 2C). The short-axis image at the level of the maximum SVG dilatation (Fig. 2D) showed that the diameter of the SVG was 37 × 35mm. The SVG aneurysm contained a thrombus and eccentric coronary artery lumen, and it compressed the right atrium. Conventional coronary angiography also demonstrated a tortuously dilated SVG graft but failed to show associated thrombus. With hesitation to carry out surgical treatment, the patient was maintained on oral anticoagulant therapy uneventfully. Saphenous vein graft aneurysm after CABG is a rare condition. There are approximately 70 cases reported in the literature. The mechanism of SVG aneurysm formation is uncertain, but it is frequently associated with atherosclerosis and hyperlipidemia. Patients with SVG aneurysm are usually asymptomatic, but are in a potentially fatal situation, since SVG aneurysms may develop myocardial ischemia due to occlusion and periodic emboli, and rupture. In asymptomatic patients, an abnormal mass detected on Y. Sato (*) · M. Ichikawa · K. Nakanishi · N. Matsumoto · S. Yoda · Y. Kasamaki · T. Takayama · T. Uchiyama · S. Saito Department of Cardiology, Nihon University School of Medicine, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8309, Japan Tel. +81-3293-1711; Fax +81-3295-1859 e-mail: yuichis@med.nihon-u.ac.jp