Yoshiyuki Masaki

Relationship between exercise tolerance and muscle strength following cardiac rehabilitation: Comparison of patients after cardiac surgery and patients with myocardial infarction

BACKGROUND AND PURPOSE Previous studies have demonstrated that cardiac rehabilitation (CR) improves exercise tolerance and muscle strength in patients with myocardial infarction (MI) and in patients after cardiac surgery. However, the association between exercise tolerance and muscular strength following CR and the comparison of relationships among various disease categories has not been fully examined. The purpose of the present study was to assess the relationship between exercise tolerance and muscle strength following CR in patients after cardiac surgery and patients with MI. METHODS AND RESULTS One hundred and four patients who participated in CR for 6 months were enrolled [post-cardiac valve surgery (VALVE), n=28; post-coronary artery bypass grafting (CABG), n=42; post-acute MI, n=34]. The exercise tolerance, thigh/calf circumferences, and muscle strength were measured before and after CR. At the baseline, the thigh circumference was significantly smaller in the VALVE group than in the MI group. There were significant positive correlations between peak VO(2) and muscle torques of the lower muscles in all groups. After 6 months, peak VO(2) and muscle torque were significantly increased in all groups (p<0.001). A positive significant correlation between percent increases in peak VO(2) and muscular strength was observed in the VALVE group (r=0.51, p<0.01), but not in the other groups. In addition, the changes in peak VO(2) and calf circumference after CR were significantly higher in the VALVE group than in the MI group. CONCLUSIONS These data suggest that exercise intolerance in patients after heart valve surgery may in part depend on decreased muscular strength. Further studies are needed to assess whether the strategy of increasing muscular strength of lower limb by programmed resistance training could be effective for improving exercise intolerance in patients after heart valve surgery and symptomatic patients with heart failure.

Impact of diabetes on muscle mass, muscle strength, and exercise tolerance in patients after coronary artery bypass grafting

BACKGROUND The impact of diabetes mellitus (DM) on muscle mass, muscle strength, and exercise tolerance in patients who had undergone coronary artery bypass grafting (CABG) has not been fully elucidated. METHODS We enrolled 329 consecutive patients who received cardiac rehabilitation (CR) after CABG (DM group, n=178; non-DM group, n=151) and measured lean body weight, mid-upper arm muscle area (MAMA), and handgrip power (HGP) at the beginning of CR. We also performed an isokinetic strength test of the knee extensor (Ext) and flexor (Flex) muscles and a cardiopulmonary exercise testing at the same time. RESULTS No significant differences in risk factors, including age, gender, number of diseased vessels, or ejection fraction were observed between the 2 groups. The levels of Ext muscle strength, peak oxygen uptake, and anaerobic threshold were significantly lower in the DM group than in the non-DM group (all p<0.05). Both peak oxygen uptake and MAMA correlated with Ext and Flex muscle strength as well as HGP (all p<0.005). The MAMA, HGP, and Ext muscle strength were lower in patients who received insulin therapy than in those who did not. Interestingly, fasting glucose levels significantly and negatively correlated with Ext muscle strength. CONCLUSIONS These data suggest that DM patients had a lower muscle strength and exercise tolerance than non-DM patients. Moreover, a high glucose level may affect these deteriorations in DM patients after CABG.

Effects of cardiac rehabilitation in patients with metabolic syndrome after coronary artery bypass grafting

BACKGROUND Cardiac rehabilitation (CR) has numerous beneficial effects, including the modification of coronary risk factors and improvement of the prognosis, in patients with coronary artery disease (CAD). Limited data are available regarding the effects of CR on the physical status and risk factors in patients with metabolic syndrome (MetS) after coronary artery bypass grafting (CABG). METHODS AND RESULTS We enrolled 32 patients with MetS after CABG, who participated in a supervised CR program for 6 months. Metabolic parameters, blood chemistry, exercise tolerance, and muscle strength of the thigh were measured before and after CR. After CR: (1) the body mass index, waist circumference, and fat weight significantly decreased; (2) peak V O(2) and anaerobic threshold were significantly increased; (3) isokinetic peak torques of knee extensor and flexor muscles significantly increased; (4) metabolic scoring defined by the number of the modified Adult Treatment Panel criteria of the US National Cholesterol Education Program was significantly improved; (5) serum concentration of high-sensitivity C-reactive protein also significantly decreased. CONCLUSIONS These results suggest that CR might be useful for patients with MetS after CABG.

Clinical significance of the measurements of plasma N-terminal pro-B-type natriuretic peptide levels in patients with coronary artery disease who have undergone elective drug-eluting stent implantation

BACKGROUND N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a diagnostic biomarker for patients with congestive heart failure (CHF). However, the clinical significance of measurements of NT-proBNP levels in patients with coronary artery disease (CAD) who have undergone drug-eluting stent (DES) implantation has not been fully elucidated. METHODS AND RESULTS We recruited 280 patients with documented CAD who were scheduled for elective coronary intervention and also age- and gender-matched 140 healthy subjects. Subjects with acute coronary syndrome, ongoing CHF, and stage IV or V chronic kidney disease were excluded. We measured the plasma NT-proBNP levels and followed the CAD patients who have undergone DES implantation for up to 62 months until occurrence of major adverse cardiovascular events (MACE). Plasma NT-proBNP levels were significantly higher in CAD patients compared to control subjects (p<0.0001). In the CAD group, 25 patients developed MACE and the NT-proBNP levels in the MACE group were significantly higher compared to that in the non-MACE group (p=0.005). After adjusting for the confounding factors, high NT-proBNP levels were observed to be independent factors for CAD (p<0.0001) and MACE (p=0.021). CONCLUSIONS These results demonstrated that the measurements of NT-proBNP levels may be useful in identifying high-risk subjects among CAD patients who have undergone elective DES implantation.

An adult case of polysplenia syndrome associated with sinus node dysfunction, dextrocardia, and systemic venous anomalies.

A 54-year-old woman was referred to our hospital for symptomatic sinus bradyarrhythmia with a sinus pause of 8 seconds. She was diagnosed with dextrocardia during childhood and discovered to have heterotaxy syndrome when she had an appendectomy during her teenager years. Chest and abdominal examinations by computed tomography showed multiple spleens located on the right side and abnormal drainages of the superior and inferior vena cava. Left isomerism was diagnosed by bilaterally bilobed lungs. Because of a patent bilateral superior vena cava, pacemaker leads were implanted using the right cephalic vein approach. Her fainting symptoms disappeared after pacemaker implantation.

The use of serum bepridil concentration as a safe rhythm control strategy in patients with atrial tachyarrhythmias

The aim of this study was to evaluate the clinical significance of serum bepridil (Bep) concentration (SBC) for safely managing patients with atrial tachyarrhythmias (AT).