Reisuke Yuyama

The Effect of Residential Exercise Training on Baroreflex Control of Heart Rate and Sympathetic Nerve Activity in Patients With Acute Myocardial Infarction

STUDY OBJECTIVES Exercise training has been shown to favorably affect the prognosis after acute myocardial infarction (AMI), but the mechanisms of such favorable effects remain speculative. The aim of this study was to determine whether exercise training improves baroreflex control of heart rate and muscle sympathetic nerve activity (MSNA) in patients with AMI. DESIGN Prospective randomized clinical study. PARTICIPANTS Thirty patients with an uncomplicated AMI were randomized into trained or untrained groups. Arterial BP, heart rate, and MSNA were measured at rest, and during baroreceptor stimulation (phenylephrine infusion) and baroreceptor deactivation (nitroprusside infusion). These measurements were performed at baseline and after 4 weeks of exercise training. MEASUREMENTS AND RESULTS Peak oxygen uptake increased significantly (12.3 +/- 10.7% [mean +/- SD]) with exercise training. Resting MSNA reduced from 34 +/- 12 to 27 +/- 8 bursts/min in the trained group but not in the untrained group. Arterial baroreflex sensitivity (BRS) [from 8.9 +/- 3.0 to 10.3 +/- 3.0 ms/mm Hg, p < 0.05] and MSNA response to baroreceptor stimulation (change of integrated MSNA from - 47 +/- 23 to - 70 +/- 21%, p < 0.01) improved significantly in the trained group, but not in the untrained group. Despite baroreceptor deactivation improving MSNA response in both groups, there was no significant difference between the two groups. CONCLUSIONS Exercise training increased arterial BRS and decreased sympathetic nerve traffic after AMI, which indicate that the sympathoinhibitory effect of exercise training may, at least in part, contribute to the beneficial effect of exercise training in patients with AMI.

Candesartan and arterial baroreflex sensitivity and sympathetic nerve activity in patients with mild heart failure

The purpose of this study was to investigate the effects of candesartan on arterial baroreflex sensitivity (BRS) and sympathetic activity in patients with mild heart failure (HF). Arterial pressure, heart rate, plasma renin activity, plasma angiotensin II and noradrenaline, and muscle sympathetic nerve activity (MSNA) were measured before therapy and after 4 weeks in 20 patients with mild HF. Patients were assigned to a candesartan group (n = 10) or a placebo group (n = 10). Baroreflex sensitivity was assessed by using phenylephrine. Candesartan induced an increase in plasma renin activity and plasma angiotensin II associated with a reduction in arterial pressure without affecting heart rate. Although plasma noradrenaline was unchanged (320 ± 322 pg/ml to 339 ± 104 pg/ml), MSNA decreased significantly (52 ± 11 bursts/min to 42 ± 9 bursts/min; p < 0.01)) and BRS increased significantly (6.9 ± 3.6 msec/mm Hg to 10.2 ± 3.3 msec/mm Hg; p < 0.01) after candesartan. However, there were no significant changes in the measured variables in the placebo group. These data indicate that candesartan treatment enhanced BRS and reduced sympathetic activity in patients with mild HF. Thus, the inhibitory effect of candesartan on sympathetic activity may, at least in part, contribute to the beneficial effect of angiotensin II receptor blockade in patients with mild HF.

Iodine 123-metaiodobenzylguanidine imaging reflect generalized sympathetic activation in patients with left ventricular dysfunction

Background:  Iodine 123‐metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. To determine the role of MIBG imaging as a measure of generalized sympathetic nerve activity, MIBG imaging was evaluated with muscle sympathetic nerve activity (MSNA) and plasma norepinephrine (noradrenaline) level in patients with old myocardial infarction.

Effect of angiotensin-converting enzyme inhibitor on cardiopulmonary baroreflex sensitivity in patients with acute myocardial infarction ☆

We evaluated the effect of angiotensin-converting enzyme inhibition (quinapril) on cardiopulmonary baroreflex sensitivity in 30 patients with uncomplicated myocardial infarction (quinapril group, 15 patients; placebo group, 15 patients) at 5 and 10 days after the onset of myocardial infarction. This study indicates that quinapril improved cardiopulmonary baroreflex and thus reduced sympathetic outflow in patients with acute myocardial infarction.

Effect of pioglitazone on arterial baroreflex sensitivity and sympathetic nerve activity in patients with acute myocardial infarction and type 2 diabetes mellitus.

Abstract: Pioglitazone has been shown to reduce the occurrence of fatal and nonfatal myocardial infarction (MI) in type 2 diabetes mellitus (DM). However, the mechanisms of such favorable effects remain speculative. The aim of this study was to investigate the effect of pioglitazone on arterial baroreflex sensitivity (BRS) and muscle sympathetic nerve activity (MSNA) in 30 DM patients with recent MI. Patients were randomly assigned to those taking pioglitazone (n = 15) and those not taking pioglitazone (n = 15) at 4 weeks after the onset of MI. BRS, MSNA, calculated homeostasis model assessment of insulin resistance index (HOMA-IR), and plasma adiponectin were measured at baseline and after 12 weeks. Pioglitazone increased plasma adiponectin (from 6.9 ± 3.3 &mgr;g/dL to 12.2 ± 7.1 &mgr;g/dL) and reduced HOMA-IR (from 4.0 ± 2.2 to 2.1 ± 0.9). In the pioglitazone group, MSNA decreased significantly (from 37 ± 7 bursts/min to 25 ± 8 bursts/min) and BRS increased significantly (from 6.7 ± 3.0 to 9.9 ± 3.2 ms/mm Hg) after 12 weeks. Furthermore, a significant relationship was found between the change in MSNA and HOMA-IR (r = 0.6, P = 0.042). Thus, pioglitazone decreased the sympathetic nerve traffic through the improvement of insulin resistance in DM patients with recent MI, which indicate that the sympathoinhibitory effects of pioglitazone may, at least in part, have contributed to the beneficial effects of pioglitazone.

Early prediction of regional functional recovery in reperfused myocardium using single-injection resting quantitative electrocardiographic gated SPET

Abstract. By evaluating concordant or discordant perfusion and systolic wall thickening patterns, resting quantitative electrocardiographic (ECG) gated single-photon emission tomography (SPET) can identify various myocardial pathological conditions with different functional recovery after revascularisation therapy. However, no data are available on the ability of this methodology to predict regional functional recovery after primary percutaneous transluminal coronary angioplasty (PTCA). This study evaluated whether single-injection ECG gated SPET imaging performed at rest with 99mTc-tetrofosmin early after successful PTCA can predict recovery of regional wall motion. ECG gated SPET was performed 3 days and 3 weeks after successful PTCA in 26 patients. Regional functional parameters were automatically calculated with a 20-segment model on the day 3 image, and segments with perfusion/thickening mismatch were defined as showing preserved perfusion (>55% uptake on the end-diastolic image: mean–standard deviation of the normal value) without systolic wall thickening (mean–standard deviation of the normal value). On the third day, the regional wall motion score of 37 mismatched segments (3.8±2.1) was significantly lower than that of 41 matched normal segments (6.0±2.9), but was significantly higher than that of 108 matched abnormal segments (1.4±1.9, both P<0.01). At 3 weeks after acute MI, the regional wall motion score of mismatched segments (6.4±3.9) improved to the level of matched normal segments (7.1±3.0) and was significantly higher than that of matched abnormal segments (2.5±3.0, P<0.01). Absolute change in the regional wall motion score (3 days to 3 weeks) of mismatched segments (2.6±3.5) was significantly greater than that in the regional wall motion score of matched normal segments and matched abnormal segments (1.1±1.3 and 1.2±2.6, respectively, both P<0.05). Twenty-seven of 37 segments (73%) with perfusion/thickening mismatch showed significant improvement in regional wall motion, whereas improvement in regional wall motion was observed in 22 of 108 segments (20%) with matched abnormal segments and 6 of 41 segments (15%) with matched normal segments. Segments with perfusion/thickening mismatch had a significantly higher incidence of regional functional improvement than did matched abnormal or matched normal segments (χ2=42.3, P<0.01). Thus, by estimating both perfusion and wall thickening, single-injection resting ECG gated SPET imaging with 99mTc-tetrofosmin early after primary PTCA can predict recovery of regional wall motion after successful reperfusion.

Correlation of Heart Rate Turbulence with Sympathovagal Balance in Patients with Acute Myocardial Infarction

To examine the relationship among heart rate turbulence parameters, arterial baroreflex sensitivity, and cardiac sympathetic nerve activity, 15 patients with acute myocardial infarction, presenting with sinus rhythm and ≧3 ventricular premature beats/24hr were studied at least 2 weeks after acute myocardial infarction. Turbulence onset (TO) and turbulence slope (TS) were averaged from 3 respective ventricular premature beats. Early heart-to-mediastinum ratio (H/M), delayed H/M, and washout rate were calculated from iodine-123-metaiodobenzylguanidine (123I MIBG) scintigraphy. Arterial baroreflex sensitivity was calculated by phenyrephrine method. Arterial baroreflex sensitivity correlated significantly with TO (r = − 0.75, p < .01) and TS (r = 0.53, p < .05). TO had no correlations with early H/M, delayed H/M, and washout rate. There were no significant correlations between TS and early H/M. However, TS had significant correlation with delayed H/M(r = 0.74, p < .01) and washout rate (r = − 0.71, p < .01). Thus, heart rate turbulence of TO and TS parameters depend on sympathovagal balance.

Quantitative estimation of myocardial salvage after primary percutaneous transluminal coronary angioplasty in patients with angiographic no reflow

Angiographic Thrombolysis in Myocardial Infarction (TIMI) flow grade <2 after primary percutaneous transluminal coronary angioplasty (PTCA), defined as angiographic no reflow, predicts poor left ventricular functional recovery and survival in patients with acute myocardial infarction (MI). To determine the relation between angiographic coronary flow and myocardial salvage in the acute phase of MI, serial technetium-99m tetrofosmin imaging was performed before, immediately after and 1 month after PTCA in 117 patients. Angiographic no reflow was observed in 23 patients (20%; group 1), while 94 patients did not have angiographic no reflow (group 2). Although there was no significant difference in the defect score before PTCA between the two groups (group 1, 14.4±5.7; group 2, 13.5±4.6), the defect score immediately after PTCA in group 1 was significantly higher than that in group 2 (group 1, 12.8±5.1; group 2, 8.9±4.6; P <0.0001). A significantly smaller change in the defect score after PTCA (before minus immediately after PTCA) was observed in group 1 as compared with group 2 (group 1, 1.7±2.0; group 2, 4.5±2.9; P <0.0001). Twenty patients in group 1 (87%) had impaired myocardial reperfusion (<4 change in the defect score immediately after PTCA), as compared with 36 patients (38%) in group 2; this difference was significant (χ2=17.5, P <0.0001). The sensitivity, specificity and accuracy of angiographic no reflow in estimating impaired myocardial reperfusion were 36%, 95% and 67%, respectively. Thus, angiographic no reflow is a highly specific, although not sensitive, marker of impaired myocardial reperfusion immediately after primary PTCA.

Traumatic ventricular septal rupture associated with rapid progression of heart failure despite low Qp/Qs ratio: a case report

BackgroundVentricular septal rupture (VSR) secondary to blunt chest trauma is rare and associated with a diverse range of symptoms and clinical courses as well as disease severity. We present a case of traumatic VSR in which rapid progression of heart failure was observed in spite of relatively low pulmonary to systemic blood flow (Qp/Qs) ratio.Case presentationA 40-year-old male was transported to the emergency department approximately 12 h after blunt chest trauma. VSR was diagnosed by echocardiography, and right heart catheterization revealed a Qp/Qs ratio of 1.52. Although medical treatment was initially attempted, subsequent rapid progression of heart failure necessitated emergent surgical repair of VSR.ConclusionsBecause small, asymptomatic VSR often close spontaneously, surgical repair of traumatic VSR is indicated when the shunt rate is relatively large or heart failure is present. However, the present case highlights the need to consider emergent surgical repair of traumatic VSR, even when the shunt rate is relatively small.

Previous Statin Therapy Improves Clinical Outcome of Patients withST-Segment Elevation Myocardial Infarction Undergoing PrimaryPercutaneous Coronary Intervention

Background: Statin treatment has been shown to reduce the risk of coronary artery disease and improve the outcome of patients with acute myocardial infarction. However, the effects of previous statin treatment on the clinical course of subsequent acute myocardial infarction remain unclear. This study was designed to investigate whether previous statin therapy influences the clinical outcome of patients with ST-Segment Elevation Myocardial Infarction (STEMI) treated with primary Percutaneous Coronary Intervention (PCI). Methods: We evaluated the clinical outcome of 350 patients with STEMI undergoing primary PCI, of which 91 received previous statin treatment (statin group) and 259 did not (non-statin group). Myocardial perfusion, infarct size, inflammatory responses, and Major Adverse Cardiovascular Events (MACE) were evaluated. Results: The frequency of MACE at 1 month after PCI was significantly lower in the statin group than the nonstatin group (4.4% vs. 13.9%, p=0.014). Post-PCI peak creatine kinase was significantly lower in the statin group median, (interquartile range): (1246 [504-3301] vs. 2235 [952-4083] IU/ml; p=0.002), whereas peak high-sensitivity C-reactive protein did not significantly differ between the two groups (p=0.287). The frequency of ST-segment resolution after PCI was significantly higher in the statin group (90.1% vs. 76.8%; p=0.006), as was the frequency of Thrombolysis in Myocardial Infarction grade 3 coronary flow (p=0.008). Myocardial blush grade was similar in both groups (p=0.839). Multivariate logistic regression analysis revealed previous statin treatment, hs-CRP, blood glucose, and age to be independent predictors of MACE. Conclusion: Previous statin therapy enhances coronary flow, reduces infarct size, and improves clinical outcome of STEMI patients treated with primary PCI.