Satoshi Hirasaki

Intracoronary adenosine 5′-triphosphate as an alternative to papaverine for measuring coronary how reserve

Abstract In conclusion, 50 μg of intracoronary ATP exhibited a vasodilator potency similar to that of papaverine without producing any marked changes in hemodynamics or a prolongation of the QTc. Intracoronary ATP may therefore be safer than papaverine for measuring CFR; more conclusive evidence about the safety of intracoronary ATP will have to await the conclusion of larger trials.

Abnormal course, abnormal flow, and systolic compression of the septal perforator associated with impaired myocardial perfusion in hypertrophic cardiomyopathy

BACKGROUND The septal perforators in hypertrophic cardiomyopathy (HCM) show systolic compression. The compression is thought to be related to the malpositioned septal perforators, but its relation to the development of myocardial ischemia remains controversial. METHODS We examined echocardiographically the blood flow and course of the major septal perforator in 142 consecutive patients with HCM; of these, 94 underwent coronary angiography to assess systolic compression of the septal perforators and 110 had thallium-201 scintigraphy. We then analyzed the relation of the findings in comparison with the results in 15 patients with valvular aortic stenosis (AS). RESULTS The major septal perforator was visualized in 82 patients with HCM and in 8 patients with AS. The visualization did not depend on the pressure gradient between the left ventricle and aorta in the HCM patients, but did in the AS patients. In AS the perforator always showed a normal course near to, and convexly toward, the right ventricle. In 71 of the 82 HCM patients, the perforator was distant from the right-sided endocardium of the ventricular septum and often convex toward the left. The greater the leftward deviation, the higher was the grade of compression. In 48 of the 82 patients with HCM and in all of the 8 patients with AS who showed the flow signal, the septal perforator showed systolic retrograde flow; in the patients with HCM there was a significant correlation (r = 0.54, P <.05) between the peak velocity and the degree of leftward deviation. Furthermore, higher degrees of the leftward deviation and higher degrees of the systolic compression of the major perforator were each associated with a higher incidence of exercise-induced defect of thallium-201. CONCLUSION The echocardiographic, angiographic, and scintigraphic findings in HCM may be closely related to one another. We speculate that the series of abnormalities is initiated by a high intramural pressure and impedance on the septal perforators due to their deviation toward the left.

Reverse redistribution of Tc-99m-tetrofosmin in exercise myocardial SPECT in patients with hypertrophic cardiomyopathy

We examined the usefulness of Tc-99m-tetrofosmin in detecting exercise induced perfusion abnormalities in patients with hypertrophic cardiomyopathy (HCM) and to clarify time-related changes in myocardial distribution of Tc-99m-tetrofosmin after a single injection. We studied 44 consecutive patients with HCM by means of exercise/rest Tc-99m-tetrofosmin single photon emission computed tomography (SPECT). After injecting 370 MBq of Tc-99m-tetrofosmin at the peak exercise, the early SPECT imaging was performed at 30 min (EX-30) and the delayed imaging at 180 min (EX-180). Immediately after the delayed imaging, 740 MBq of Tc-99m-tetrofosmin was injected in the resting state, and the rest SPECT imaging was performed 30 min later. Exercise-induced regional perfusion defects and/or apparent reversible left ventricular cavity dilation were identified in 26 (68.2%) of the 44 patients. When EX-30 images and EX-180 images were compared, reverse redistribution was confirmed in 36 patients (81.8%). Reverse redistribution was detected most frequently in the septal portion of the anterior wall, followed by the septal portion of the posterior wall and the septum. Exercise/rest Tc-99m-tetrofosmin myocardial imaging was a useful method for assessing myocardial perfusion abnormalities in patients with HCM. Reverse redistribution was detected very frequently on early and delayed images of exercise. We assumed that reverse redistribution may reflect a retention disorder of Tc-99m-tetrofosmin caused by some metabolic dysfunction of myocytes.

Systolic Outward Motion of the Left Ventricular Apical Wall as Detected by Magnetic Resonance Tagging in Patients with Apical Hypertrophic Cardiomyopathy

Patients with apical hypertrophic cardiomyopathy (APH) associated with paradoxic jet flow (ie, diastolic flow away from the apex) may gradually develop an apical aneurysm, which often leads to arrhythmia and mural thrombus formation. We observed systolic outward motion of the left ventricular apical myocardium in patients with APH using a magnetic resonance tagging procedure and examined the relationship of the outward motion to echocardiographic and scintigraphic findings and to cardiac events. Systolic displacement of the myocardial tags of the apical region perpendicular to the long axis in the 4-chamber view was recorded in 31 patients with APH. Of these patients, 14 showed no outward movement of tags (group A), and 17 showed outward movement (group B). In group B, apical hypertrophy was more severe (35 +/- 7 mm vs. 29 +/- 6 mm, p < 0.05), paradoxic jet flow was more frequent (64% vs. 14%, p < 0.05) and the defect score in I-123-beta-methyliodophenylpentadecanoic acid scintigraphy was higher (2.1 +/- 0.7 vs. 1.3 +/- 0.7, p < 0.01). During a mean follow-up period of 55 months, only 1 patient experienced paroxysmal atrial fibrillation in group A. In group B, 1 patient died suddenly, 1 was admitted to hospital because of congestive heart failure, 2 developed angina pectoris, 2 exhibited non-sustained ventricular tachycardia, and 1 showed multifocal premature ventricular contraction; in these 7 patients the outward movement was greater than in the 10 patients in Group B who had no cardiac events (1.00 +/- 0.59 vs. 0.52 +/- 0.40, p < 0.05). Hence, our results show that outward tag displacement is frequently associated with severe apical hypertrophy, paradoxic jet flow, apical ischemia, and cardiac events. The tagging method may be useful in assessing the severity of APH and predicting the occurrence of cardiac events at an early stage.

Slow-fast Form of Atrioventricular Nodal Reentrant Tachycardia with Unusual Retrograde Activation in the Right Atrium —Possible Conduction Disturbance across the Tendon of Todaro Related to the Genesis of Positive Component of Biphasic Retrograde P Wave—

We report a rare case of slow‐fast form of atrioventricular nodal reentrant tachycardia with delayed activation in the low septal right atrium (His bundle area). During supraventricular tachycardia (SVT), electrocardiogram showed “pseudo‐positive P waves” in II, III, and aVF leads. SVT was induced by atrial extrastimulus with marked AH prolongation (i.e., jump phenomenon). Ventricular pacing showed a decremental retrograde conduction without jump phenomenon. Double atrial potentials were observed in the His bundle area during SVT and during ventricular pacing. The first electrogram of these split potentials, which was the earliest activation during SVT and during ventricular pacing, showed a dull and small deflection, whereas the second electrogram was sharp and clear. The interval of these discrete potentials was 70 msec during SVT. After a standard slow pathway ablation, SVT could never be induced by any programmed stimuli. It was concluded that in this case, the conduction disturbance across the tendon of Todaro was likely to cause the delayed atrial activation in the His bundle area, which created the pseudo‐positive (biphasic. retrograde P wave.