Atsutoshi Hatada

Acute reductions in blood flow restricted to the dorsomedial medulla induce a pressor response in rats.

Objectives The brainstem nucleus of the solitary tract (nucleus tractus solitarii, NTS) is a pivotal region for regulating the set-point of arterial pressure, the mechanisms of which are not fully understood. Based on evidence that the NTS exhibits O2-sensing mechanisms, we examined whether a localized disturbance of blood supply, resulting in hypoxia in the NTS, would lead to an acute increase in arterial pressure. Methods Male Wistar rats were used. Cardiovascular parameters were measured before and after specific branches of superficial dorsal medullary veins were occluded; we assumed these were drainage vessels from the NTS and would produce stagnant hypoxia. Hypoxyprobe-1, a marker for detecting cellular hypoxia in the post-mortem tissue, was used to reveal whether vessel occlusion induced hypoxia within the NTS. Results Following vessel occlusion, blood flow in the dorsal surface of the medulla oblongata including the NTS region showed an approximately 60% decrease and was associated with hypoxia in neurons located predominantly in the caudal part of the NTS as revealed using hypoxyprobe-1. Arterial pressure increased and this response was pronounced significantly in both magnitude and duration when baroreceptor reflex afferents were sectioned. Conclusion These results suggest that localized hypoxia in the NTS increases arterial pressure. We suggest this represents a protective mechanism whereby the elevated systemic pressure is a compensatory mechanism to enhance cerebral perfusion. Whether this physiological mechanism has any relevance to neurogenic hypertension is discussed.

Adrenomedullin 2 microinjection into the nucleus tractus solitarius elevates arterial pressure and heart rate in rats

Adrenomedullin 2 (AM2), a novel member of the calcitonin gene-related peptide family, has emerged as a multifunctional peptide controlling endocrine and cardiovascular functions and physiological behaviors. Both central and peripheral administration of AM2 can have profound effects on systemic and/or pulmonary circulation in mammals. However, the target nuclei of AM2 and the role of central AM2 in cardiovascular regulation remain unknown. In the present study, we microinjected AM2 into the rat nucleus tractus solitarius (NTS), the central termination site of baroreceptor afferents. Consistent with previous reports showing the hypertensive effect of intracerebroventricular administration of AM2, the direct microinjection of the peptide into the NTS increased arterial pressure as well as heart rate in rats. Importantly, this effect of AM2 on cardiovascular regulation was significantly attenuated by an antagonist of receptor components for AM2 that were abundant in the rat NTS. Our results indicate that AM2 may play an important role in the regulation of the cardiovascular system at the NTS level.

Comparison of the waveforms of transit-time flowmetry and intraoperative fluorescence imaging for assessing coronary artery bypass graft patency.

PurposeAn intraoperative fluorescence imaging (IFI) system, which can provide visual images, could be the common method for assessing graft patency intraoperatively. We conducted a prospective comparison of the diagnostic accuracy of both the fast Fourier transformation (FFT) analysis of transit-time flowmetry (TTFM) waveform and the IFI system to determine graft failure.MethodsThe study included 10 saphenous vein grafts (SVGs), all of which were aortocoronary grafts. Each patient underwent isolated coronary artery bypass grafting (CABG), including conventional CABG or off-pump CABG, and then underwent X-ray angiography after CABG. When intraoperative hemodynamics had stabilized, the grafts were evaluated with both the IFI system and TTFM. Based on the obtained flow profile of TTFM, certain variables were calculated. The waveforms of TTFM were analyzed with the FFT series. Harmonic distortion (HD) was calculated from the amplitudes, and the fundamental frequency was thus determined using the FFT series.ResultsThe IFI system demonstrated a satisfactory flow of all grafts. X-ray angiography demonstrated that one SVG was 75% stenosed, and the others were patent. The mean graft flow (MGF) and the pulsatility index (PI) of the patent SVGs were not significantly different from those of the stenosed SVG. The HD of the patent SVGs was significantly different from that of the stenosed SVG.ConclusionThe HD of the TTFM waveform can provide better diagnostic accuracy for detecting clinically significant grafts than MGF and PI of TTFM and the IFI system.

Ultrasonographic measurement of intima-media thickness of the carotid artery before coronary artery bypass grafting.

PurposeWe evaluated the usefulness of measuring intima-media thickness (IMT) of the carotid artery by ultrasonography before coronary artery bypass grafting (CABG).MethodsSeventy-three patients who underwent carotid ultrasonography before CABG were selected for this study. The maximum IMT (max IMT) in the bilateral common carotid artery was used as the index of carotid ultrasonography. As a quantitative measure of coronary atherosclerosis, we calculated Gensini’s coronary score (GCS) from the preoperative coronary angiography.ResultsThere was a positive correlation between the max IMT and the GCS. Furthermore, the max IMT of the patients with myocardial infarction was significantly greater than that of the patients with angina pectoris.ConclusionsCarotid ultrasonography before CABG is useful, not only for the morphological evaluation of the stenotic lesions of the neck vessels, but also for the quantitative prediction of atherosclerosis in the native coronary artery. The max IMT may predict the progression of atherosclerotic change of the native coronary artery from angina pectoris to myocardial infarction.

Long-Term Results of Crossover Bypass for Iliac Atherosclerotic Lesions in the Era of Endovascular Treatment: The Re-ACTION Study ( Re trospective A ssessment of C rossover Bypass as a T reatment for I liac Lesi ON s)

Objective: The aim of this study was to elucidate the long-term results of crossover bypass (CB) for iliac atherosclerotic lesions in the era of endovascular treatment (EVT). Methods: A retrospective multicenter cohort study was performed. CB was performed in 242 patients between 2003 and 2014 by vascular surgeons at multiple medical centers in Japan. Results: Perioperative mortality was 1.7%. Primary patency rates were 86% at 5 years and 82% at 8 years. Univariate analysis showed that critical limb ischemia (Rutherford class 4–6), vein graft, and superficial femoral artery occlusion were significantly associated with low primary patency. In multivariate analysis, only critical limb ischemia influenced primary patency. The secondary patency rate was 87% at both 5 and 8 years. The limb salvage rate was 98% at both 5 and 8 years. The overall survival rates were 71% at 5 years and 49% at 8 years. Conclusion: The long-term results of CB were good in our study, compared with previous reports. Our results suggest that CB remains an option for the arterial reconstruction in unilateral iliac occlusive disease after EVT failed.

Left ventricular ball-like thrombus after acute myocardial infarction with essential thrombocythemia

Left ventricular (LV) thrombus after acute myocardial infarction (AMI) is a frequent complication that is associated with a risk of systemic embolism. Essential thrombocythemia (ET) has opposing tendencies towards hemorrhage and thrombogenesis and it can cause AMI via thrombogenesis. Ball-like LV thrombus is associated with a high risk of systemic embolism. We describe surgical resection of LV ball-like thrombus from a patient with ET. A 60-year-old woman presented at our hospital with transient ischemic attack accompanied by transient hemiplegia. Ultrasonic cardiography revealed a mobile ball-like thrombus in the LV after transmural AMI of the anterior wall. We performed emergency LV thrombectomy because of the mobile LV thrombus with embolism. Platelet aberrations and pathological bone marrow findings were consistent with a diagnosis of ET. We administered the patient with anti-coagulation drugs and the DNA replication inhibitor hydroxycarbamide to decrease the platelet count. She continues to survive and is doing well without major postoperative complications. <Learning objective: Essential thrombocythemia (ET) can cause acute myocardial infarction with left ventricular (LV) thrombus via thrombogenesis. After we describe surgical resection of LV ball-like thrombus from a patient with ET, the patient was administered with anti-coagulation drugs and the DNA replication inhibitor hydroxycarbamide to decrease the platelet count. The patient continues to survive and is doing well without major postoperative complications.>.

Perioperative Change of Atrial Natriuretic Peptide and Brain Natriuretic Peptide in Relation to the Surgery for Abdominal Aortic Aneurysm

腹部大動脈瘤(AAA)手術症例における周術期の血中心房性ナトリウム利尿ペプチド(ANP),脳性ナトリウム利尿ペプチド(BNP)値の変動からみた心機能の評価につき検討を行った.AAA手術症例34例を対象とし,虚血性心疾患を合併した群(IHD合併群:22例)と非合併群(12例)の2群に分類した.ANP,BNP値を術前,術後1日目,術後2日目に測定した.全症例でANP,BNP値は術後有意に上昇した(p>0.05).IHD合併群ではANP,BNP値ともにいずれの時期でも非合併例より高値を示した(p<0.05).ANP,BNP値の変化からみてAAAの周術期には心筋への負荷が認められ,術後管理に注意を要すると思われた.