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Biomedical subjects

N Doba

Publications and source records attributed to N Doba.

At least 19 recordsLinked to original sources
PubMed1998

Left ventricular geometric patterns and QT dispersion in borderline and mild hypertension: their evolution and regression.

To investigate whether QT dispersion increases in borderline and mild hypertension during a longitudinal observation of > 3 years and whether it is improved with medications, left ventricular geometric patterns and QT dispersion were studied with special regard to their longitudinal changes in 85 male borderline and mild hypertensive subjects with left ventricular mass index < 125 g/m2. These subjects were followed for > 3 years without medication. Thirty-two patients with a left ventricular mass index > 125 g/m2 at the end of follow-up period were further observed using antihypertensive drugs for an additional 3 years. Echocardiograms and electrocardiograms were obtained at the beginning and end of the follow-up period. At the end of the follow-up period, subjects were classified into four groups based on ventricular geometric patterns determined by left ventricular mass index and relative wall thickness in diastole. The QT dispersion was greater in patients with concentric hypertrophy (56+/-18 msec) than in patients with normal geometry (41+/-17 msec) (P < .05) and increased significantly in the former group during the follow-up period. After medication, the left ventricular mass index regressed and the QT dispersion decreased (from 55+/-21 to 50+/-26 msec, P < .01) in these patients. Thus, these findings suggest that changes in the QT dispersion reflect both concentric evolution and regression of left ventricular hypertrophy.

Adult↗
PubMed1998

Effects of an ACE inhibitor and a calcium channel blocker on cardiovascular autonomic nervous system and carotid distensibility in patients with mild to moderate hypertension.

We investigated the relationship between cardiovascular autonomic nervous system function and carotid arterial distensibility during treatment with an angiotensin converting enzyme inhibitor (derapril) or a calcium channel blocker (manidipine) for hypertension. In 37 patients with hypertension, autonomic function was assessed by heart rate variability and baroreceptor sensitivity using phenylephrine injection. Left ventricular mass index and carotid arterial distensibility were assessed by ultrasound examinations. Before the medication, both baroreceptor sensitivity and heart rate variability correlated with carotid arterial distensibility, but not with left ventricular mass index by multiple regression analysis. Subsequently, patients were randomly allocated into two groups, derapril (n = 18) and manidipine (n = 19) for 20 weeks. At the end of the study, the change in baroreceptor sensitivity correlated with change in carotid arterial distensibility (r = 0.41, P < .05), but not with change in left ventricular mass index. Although derapril and manidipine decreased blood pressure and left ventricular mass index to the same extent, the former improved heart rate variability, baroreceptor sensitivity (5.0 +/- 1.9 --> 5.6 +/- 2.0 msec/mm Hg), and carotid arterial distensibility (2.1 +/- 0.8 --> 2.5 +/- 1.0 %kPa), but the latter did not improve them at all. Thus, impairment of the autonomic balance was related to the impairment of carotid arterial distensibility in hypertension; derapril, but not manidipine, significantly improved these abnormalities.

Aged↗
PubMed1998

Relationship between endothelial function and fibrinolysis in early hypertension.

Abnormalities in fibrinolysis, endothelial function, and glucose and lipid metabolism have been reported in hypertension. This study was conducted to examine the interrelationships between fibrinolytic factors, glucose and lipid metabolism, and endothelial function in hypertension. The effects of administering an angiotensin converting enzyme inhibitor, benazepril, were also examined. Blood levels of the following substances were measured in patients with borderline and mild hypertension (n=50, 51+/-19 years) and in age-matched controls (n=10): total cholesterol, triglycerides, tissue plasminogen activator activity and antigen, and plasminogen activator inhibitor type 1 activity and antigen. Insulin sensitivity was assessed by oral glucose tolerance test, and endothelial function was assessed by evaluating changes in diameter of the brachial artery during reactive hyperemia as observed by ultrasonography. Activities of tissue plasminogen activator and plasminogen activator inhibitor type 1 were both elevated in the hypertensive patients. Stepwise multiple regression analysis showed that plasminogen activator inhibitor type 1 antigen correlated with insulin sensitivity, total cholesterol levels, and triglycerides levels (P<.01). Endothelial function was negatively correlated with tissue plasminogen activator activity and antigen (P<.01). The chronic administration of benazepril (5-10 mg/d) for 20 weeks improved insulin sensitivity, endothelial function (6.6+/-3.4-->9.0+/-2.5%, P<.01), and tissue plasminogen activator activity and antigen. These results indicate that abnormalities in fibrinolysis are associated with endothelial dysfunction as well as disorders of glucose and lipid metabolism in patients with borderline and mild hypertension. The treatment of such patients with benazepril appeared to improve the impairment in fibrinolysis and endothelial dysfunction.

Adult↗
PubMed1998

Relationship between calcium channel antagonists and nocturnal hypotension and autonomic imbalance in patients with a previous myocardial infarction.

The present study was conducted to evaluate the effect of calcium channel antagonists on diurnal changes in blood pressure and on autonomic function in 71 patients who were receiving a calcium channel antagonist because they had previously suffered a myocardial infarction. Ambulatory blood pressures and Holter ECGs were recorded simultaneously for 24 h. Autonomic function was assessed by heart rate variability. Nocturnal systolic pressure was > or = 90 mmHg in 63 patients (group I) and < 90 mmHg in 8 patients (group II). Significant day to night changes in high-frequency power (from 4.3 +/- 1.2 to 4.5 +/- 1.0/m2) as well as in the ratio of low-frequency power to high-frequency power (from 1.3 +/- 0.1 to 1.1 +/- 0.2) were observed in group I. whereas such changes were blunted in group II. When the calcium antagonist was discontinued or the dose was reduced in group II, the autonomic imbalance improved along with elevation of nocturnal systolic blood pressure. Thus, nocturnal blood pressure should be monitored when such drugs are administered for the treatment of ischemic heart disease to a patient with a previous myocardial infarction. If nocturnal hypotension occurs, the dose should be reduced or the drug should be discontinued.

Adult↗
PubMed1998

Hormonal and cardiorenal responses to acute saline loading in mild congestive heart failure--the effect of angiotensin converting enzyme inhibition.

We investigated cardiorenal responses to acute saline loading in patients with mild congestive heart failure (CHF) with and without angiotensin-converting enzyme (ACE) inhibition. Saline loading (infusion of 250 ml of normal saline) was performed on 10 patients with mild CHF and 10 control subjects. Although saline loading reduced plasma renin activity and plasma angiotensin II to a similar extent in both groups, it increased cardiac output, renal blood flow, and the ratio of renal blood flow to cardiac output in the mild CHF group but not in the control group. After saline loading, urinary sodium excretion was higher in the control than in the mild CHF group. In the mild CHF group, saline loading was performed again after an ACE inhibitor (delapril) had been administered for 5 days. Although delapril increased cardiac output and renal blood flow under basal conditions, saline loading did not affect these variables. Delapril improved urinary sodium excretion after saline loading. Thus, the renin-angiotensin-aldosterone axis may contribute to cardiorenal hemodynamics and renal sodium handling in patients with mild CHF. This effect may attenuate the natriuretic response to acute saline loading, and administration of an ACE inhibitor improves this attenuation.

Adult↗
PubMed1997

The relationship of hyperinsulinemic state to left ventricular hypertrophy, microalbuminuria, and physical fitness in borderline and mild hypertension.

The relationship of the hyperinsulinemic state to left ventricular hypertrophy, left ventricular geometric patterns, microalbuminuria, and physical fitness were studied in 52 middle-aged unmedicated men with borderline and mild hypertension. Left ventricular mass index and relative wall thickness were assessed by echocardiography. Physical fitness was determined by symptom-limited maximal treadmill stress testings. The urinary concentration of microalbumin and C-peptide was measured in 24-h urine samples by radioimmunoassey. The 24-h urinary C-peptide excretion rate was correlated with left ventricular mass index (r = 0.46), relative wall thickness (r = 0.41), treadmill time (r = -0.35), normalized treadmill time (r = -0.52), systolic blood pressure at peak exercise (r = 0.29), and 24-h urinary microalbumin excretion (r = 0.48). Stepwise multiple regression analysis identified the left ventricular mass index, the 24-h urinary albumin excretion, and the normalized treadmill time as variables in the equation for the 24-h urinary C-peptide excretion. Thus, the hyperinsulinemic state is related to left ventricular hypertrophy, microalbuminuria, and impaired physical fitness in patients with borderline and mild hypertension.

Adult↗
PubMed1997

Effects of long-term antihypertensive therapy on physical fitness of men with mild hypertension.

This study was conducted to investigate the effects of long-term administration of a calcium-channel antagonist (nifedipine) and a beta-blocker (acebutolol) on physical fitness in men with mild hypertension. All subjects underwent symptom-limited treadmill stress testing and routine echocardiographic studies. Twenty-two subjects who had either a causal diastolic blood pressure of more than 105 mmHg or a left ventricular mass index (LVMI) of 125 g/m2 or more during follow-up were assigned to receive medical therapy. The other 31 men who did not meet either criterion were continuously followed-up without medication. Among the 22 treated men, the age-adjusted treadmill time (normalized treadmill time, TMTn) significantly decreased before the initiation of medication, while 31 untreated men showed no change in TMTn throughout the study. The 22 treated subjects were subsequently divided into two groups; 13 were given nifedipine and 9 were given acebutolol. All treated subjects were followed-up for more than 3 years. After treatment, the two groups showed similar reductions in blood pressure and LVMI, but a different outcome for TMTn: TMTn increased from 104 +/- 8% to 115 +/- 16% in subjects given nifedipine (p < 0.05) and decreased from 106 +/- 12% to 99 +/- 10% (p < 0.01) in those given acebutolol. Thus, the physical fitness of subjects who required medication significantly deteriorated without medication; their physical fitness improved after treatment with a calcium-channel antagonist and deteriorated after treatment with a beta-blocker.

Acebutolol↗
PubMed1997

[Clinical significance of valvular regurgitation during long-term antihypertensive therapy in patients with mild to moderate essential hypertension].

Changes in valvular function and blood pressure level during long-term pharmacological anti-hypertensive therapy were investigated in patients with mild to moderate essential hypertension. Sixty-seven patients with hypertension (mean [+/-SD] 60 +/- 10 years) were followed up for 5.4 +/- 1.6 years with antihypertensive medication. During the follow-up period, valvular dysfunction was assessed by color Doppler echocardiography. Increased mitral valve regurgitation > or = grade II and/or aortic valve regurgitation > or = grade II were aggravated in 17 patients, whereas the other 50 patients did not reveal any significant changes in valvular functions. Systolic blood pressure and end-systolic wall stress at the end of the follow-up period were higher in the aggravated group (156 +/- 30 mmHg and 79 +/- 23 dyne/cm2) than in the unchanged group (143 +/- 17 mmHg and 63 +/- 18 dyne/cm2). Dimensions of the left atrium and left ventricle at both systole and diastole were enlarged in the aggravated group (37 +/- 4 to 40 +/- 4, 31 +/- 4 to 33 +/- 4 and 48 +/- 3 to 51 +/- 3 mm, respectively), but not in the unchanged group. Nine patients in the aggravated group received additional treatment with imidapril hydrochloride over 6 months in an attempt to further reduce blood pressure levels, resulting in significant improvements in systolic blood pressure (151 +/- 12 to 129 +/- 7 mmHg), diastolic blood pressure (91 +/- 4 to 79 +/- 8 mmHg), left atrial dimension (41 +/- 3 to 39 +/- 3 mm) and left ventricular end-diastolic dimension (49 +/- 4 to 48 +/- 3 mm). Adequate pharmacological intervention can ameliorate valvular dysfunction, left ventricular enlargement and increased ventricular wall stress.

Adult↗
PubMed1997

[Ultrasound examination for hypertension].

The echocardiographic determination of left ventricular mass is useful to evaluate the severity and the prognosis of hypertension. In addition to this determination, the echocardiographic assessment of left ventricular morphology is also proposed as one of important parameters to implicate the prognosis. Recently, the clinical significance of intimal-media thickness, plaque, and diameter of carotid artery obtained by an ultrasound examination for hypertension has been discussed. While these parameters correlate well with blood pressure level and left ventricular mass, further studies are needed to establish the usefulness of the ultrasound examination of carotid artery. As a tool for research purposes, ultrasound examination is also applicable to examine organ blood flow, arterial distensibility, and arterial endothelial function. Thus, ultrasound examination for hypertension is promising either in clinical practices and research purposes.

Blood Flow Velocity↗
PubMed1997

[Studies on residual cardiovascular dysfunction in patients receiving long-term antihypertensive treatment of calcium channel blockers: with special reference to left ventricular hypertrophy, and impairments of left ventricular diastolic function and carotid arterial distensibility].

Residual cardiovascular dysfunctions including left ventricular hypertrophy, and impairment of left ventricular diastolic function and carotid arterial distensibility were investigated in hypertensive patients treated with calcium channel blockers for more than 1 year. Ultrasonographic examinations of the heart and carotid artery were performed in patients treated with calcium channel blocker alone for more than 1 year (n = 45) and in age-, sex- and weight-matched control subjects (n = 29). The following parameters were obtained: left ventricular mass index, cardiac diastolic function (A/E ratio) and carotid arterial distensibility (Distens). Hypertensive subjects were re-examined under the same conditions with the same parameters after 10 +/- 5 months. Patients with hypertension revealed no significant changes in these three parameters after 10 +/- 5 months Patients with left ventricular hypertrophy (n = 20) revealed significant impairments in diastolic function and carotid arterial distensibility (A/E = 1.42 +/- 0.25, Distens = 2.4 +/- 1.3% kPa) compared to those without left ventricular hypertrophy (n = 25) (A/E = 1.18 +/- 0.29, Distens = 3.8 +/- 1.7% kPa, p < 0.05). Patients without left ventricular hypertrophy had significantly impaired cardiovascular functions compared to the normal control group (A/E = 1.03 +/- 0.27, Distens = 6.3 +/- 2.2% kPa, p < 0.05, p < 0.01 respectively). Therefore, only reduction of blood pressure with calcium channel blocker may not be enough to improve cardiovascular organ damage, especially in patients with residual left ventricular hypertrophy, and such residual functional deteriorations must be corrected probably with another pharmaceutical modality.

Aged↗
PubMed1996

An impaired carotid sinus distensibility and baroreceptor sensitivity alter autonomic activity in patients with effort angina associated with significant coronary artery disease.

Baroreceptor sensitivity and carotid sinus distensibility were lower in patients with angina associated with significant coronary artery disease than in patients with vasospastic angina. Baroreceptor sensitivity was significantly correlated with carotid sinus distensibility in both groups of patients.

Angina Pectoris↗
PubMed1996

Prospective studies on left ventricular geometric patterns and exercise tolerance in unmedicated men with borderline and mild hypertension.

OBJECTIVE: This study was designed and conducted to assess the clinical significance of left ventricular geometric patterns and physical fitness in subjects with untreated borderline and mild hypertension. METHODS: Symptom-limited maximal treadmill stress testings and echocardiographic examinations were administered to 192 previously unmedicated men. Left ventricular geometric patterns were determined by the combined criteria of left ventricular mass index and relative wall thickness. Subjects whose left ventricular mass index was < 125 g/m2 were followed up for more than 3 years. RESULTS: Normalized treadmill time was lower and pressure rate products at peak exercise were higher in patients with concentric hypertrophy than in those with normal geometry. Of the 77 patients who revealed left ventricular mass index at baseline < 125 g/m2 and who were successfully followed without medication for more than 3 years, 18 demonstrated concentric hypertrophy at the final follow-up examination. During the follow-up period, these 18 patients had significant further augmentation of concentric geometric features, significant decreases in both cardiac output and normalized treadmill time, and significant increases in casual blood pressure and total peripheral resistance compared with those at baseline. CONCLUSION: Patients with concentric hypertrophy exhibited slightly but significantly impaired levels of physical fitness and cardiac work efficiency, and the progression of concentric hypertrophy demonstrated further impairments of these conditions. Therefore, not only lowering blood pressure, but also improving left ventricular hypertrophy, cardiovascular hemodynamics, and physical fitness might be required in patients with concentric hypertrophy.

Adult↗
PubMed1996

Left ventricular hypertrophy in mild essential hypertension. Its progression, prediction and treatment strategy.

Since the pathogenesis of left ventricular hypertrophy (LVH) in hypertension is thought to be multifactorial, the antihypertensive strategy also has to be multifaceted. Diagnosis of LVH is more reliable than ever with echocardiography either of the M-mode or 2D method. Diagnostic criteria have already been proposed by Ganau et al who classified LV morphology into 4 different sectors based on the standard values of left ventricular mass index (LVMI) and relative wall thickness in diastole (RWTd); normal, concentric remodeling, concentric hypertrophy and eccentric hypertrophy. The concentric hypertrophy pattern is the most risky with regard to prognosis. Therefore, its detection and prediction for further progression have to be conducted with relatively easy routine work-up procedures such as echocardiography and maximal exercise testing. The prediction of LVH progression has already been proposed based on several studies conducted in patients with borderline or mild hypertension. The following two predictors were defined as LVMI > 124 g/m2 and peak Ps at maximal exercise testing > 200 mmHg. Therefore, the patient who meets these criteria has to be treated with medications that are appropriately selected on an individualized basis. Both hyperinsulinemia and insulin resistance are thought to be involved in the initiation, promotion and potentiation of remodeling of the LV in hypertension. Physical fitness also seems to be decreased in a parallel manner. Selection of the most appropriate drug for a given patient has to be individually determined based on the risks that have to be corrected. Finally, arteriosclerosis, which is almost always initiated and progresses in concert with hypertension, must also be targeted with regard to such prognostic aspects as cardiovascular morbidity and mortality. Arteriosclerosis is pathogenetically independent from hypertension, but usually behaves in concert with it. Selection of medication must be focussed on an individualized basis not only for LVH, but also for improvement in arterial elasticity. Further clinical research is still needed to provide more reasonable approaches to patients with hypertension.

Angiotensin II↗
PubMed1996

[Advancement of management of arrhythmias associated with exercise testing].

Exercise-induced isolated premature contractions occur in healthy subjects, as well as in patients with cardiac disease. On the other hand, the prevalence of exercise-induced supraventricular or ventricular tachycardia is uncommon among most healthy subjects in usual clinical laboratory settings. Significant coronary heart disease may be found in patients who reveals ventricular arrhythmias during the phase of graded exercise testing. The absence of increase of heart rate during submaximal exercise usually suggests sinus node dysfunction. Exercise testing is of value when it comes to assessing the site of AV block in patients with atrioventricular (AV) block. Exercise testing is also useful to clarify arrhythmic implications for various exercise-related complaints and may help to assess risk strafication and effects of interventions. The clinical significance of induction or suppression of arrhythmia during exercise still remains to be investigated.

Arrhythmias, Cardiac↗
PubMed1996

Safety and effectiveness of exercise training in patients with silent myocardial ischemia.

The effectiveness of exercise training in patients with silent myocardial ischemia was examined. Forty patients with coronary heart disease (mean age 55 +/- 8 years) were recruited for a 12-week exercise training program. All patients underwent treadmill exercise stress testing, exercise thallium-201 single photon emission computed tomography and left heart catheterization. They were divided into three groups based on the symptoms and the results of exercise thallium scintigraphy, i.e., painful myocardial ischemia (PMI group), silent myocardial ischemia (SMI group), and non-myocardial ischemia (NMI group). Normalized treadmill time was longer in the SMI group (108 +/- 24%) than in the PMI group (86 +/- 14%, p < 0.05). All 40 patients, 14 from the PMI group, 16 from the SMI group and 10 from the NMI group, completed the whole exercise training program. A significant prolongation of treadmill time was attained in all three groups after exercise training [PMI group: from 494 +/- 105 to 632 +/- 78 sec (p < 0.05), SMI group: from 609 +/- 147 to 746 +/- 137 sec (p < 0.05), NMI group: from 572 +/- 112 to 739 +/- 13 sec (p < 0.05)]. The improvement of myocardial ischemia following exercise training was similar in the SMI and PMI groups. No adverse effects were detected throughout the program. The exercise training program adopted in this study proved safe and effective in patients with silent myocardial ischemia.

Adult↗