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Impedance cardiography may be a simple way of assessing left ventricular performance during exercise. Measurements were therefore made during exercise testing in 102 consecutive male patients with suspected coronary disease prior to cardiac catheterization. These were subsequently divided into four groups: group A, normal; group B, 1-or 2-vessel disease; group C, 3-vessel disease (groups A, B, and C, left ventricular ejection fraction (LVEF) > 55%); and group D, 3-vessel disease with LVEF < 55%. Immediately after peak exercise several impedance measures were significantly correlated with resting LVEF, especially dZ/dt (R = 0.41, < 0.001) and Heather index (R = 0.46, < 0.001). Heather index was the best discriminator between the disease groups with mean values (95% confidence intervals) of 25.7 (22.2–29.2) (group A), 21.9 (20.6–23.2) (group B), 18.4 (16.2–20.6) (group C), and 15.3 (10.3–20.3) Ωs (group D) but there was considerable overlap between groups (risk ratios 1.17 and 3.15 for any and triple-vessel coronary disease respectively). Measurements were therefore of little diagnostic value. The majority of patients with abnormal responses could be identified more simply by their poor exercise tolerance or abnormal blood pressure response. [ABSTRACT FROM PUBLISHER]

This paper studies the possible errors associated with the use of a ‘universal’ regression equation in heart rate correction when used on mechanical cardiac function parameters. Systolic time interval rate correction, using Weissler regression equations, is taken as an example. The measurements were made during the isometric handgrip test, the orthostatic test, the Valsalva manoeuvre and the cold pressor test. It was observed that in most measurements rate correction caused a significant correlation between the changes in heart rate and the rate-corrected systolic time interval. It is considered that this new dependence between heart rate and the rate-corrected parameter makes the physiological interpretation of results more difficult. Therefore it is recommended that in stress provocations mechanical cardiac function parameters should not be rate-corrected by methods based on a ‘universal’ regression equation between heart rate and the mechanical function parameter. [ABSTRACT FROM PUBLISHER]

The systolic time intervals (STI) offer temporal description of the seq uentialphases of cardiac cycle which are influenced physiologically by the same variables as affect other measures of left ventricular (LV) performance. The STI hence offer a measure of ventricular function which augments other measures of ventricular performance. Because of the extreme sensitivity of this variable and the ease of its measurement the STI are well suited for studying the effect of pharmacologic agents upon the heart. [ABSTRACT FROM PUBLISHER]

This paper updates the current view on clinical significance of systolic time intervals (STI) in estimating the cardiac changes associated with hypertension. The following three intervals were measured as STI: (1) electromechanical systole (QS2 interval); (2) left ventricular ejection time (LVET) and (3) pre-ejection period (PEP). Firstly, the influences of changes in heart rate, preload, afterload and myocardial contractility upon each interval were reviewed; secondly, clinical applications of STI in various types of hypertension such as essential hypertension, hypertension with angina pectoris and pheochromocytoma were studied. In patients with essential hypertension, there was agoodpositive correlation between PEP and left ventricular mass, and a shortening of LVET was observed only at the decompensated stage. The changes in STun angina pectoris with or without hypertension were similar and were djfferent from those in essential hypertensives. STI in patients with pheochromocytoma were characterized by a marked shortening of QS2 and LVET with normal PEP. These findings indicate the usefulness of STI in detecting cardiac changes in various types of hypertension. [ABSTRACT FROM PUBLISHER]

The alterations in the systolic time intervals caused by hypertension during pregnancy have been investigated. A group of 20 women who developed hypertension only during pregnancy (HP), and a group of 16 women who began pregnancy with established hypertension (EHP) were matched with 25 normal pregnant women (N). The study was performed (I) during the third trimester, (2) five days after delivery and (3) five weeks after delivery, both in supine and in lateral postures. In the third trimester the two hypertensive groups, when compared with the normal group, were characterized by a shorter left ventricular ejection time (LVET: 407±3 ms for the normal group v. 390±2ms for the HP group, P<0.001; v. 398±2ms for the EHP group, P<0.02), and a longer pre-ejection period (PEP,: 138±2 ms for the normal group v. 154 ± 2 ms for the HP group P<0.001; v. 145± 1 ms for the EHP group, P<0.05). When the two hypertensive groups were compared with each other the HP group showed a shortened LVET and a prolonged PEP (P<0.01), and also a slower heart rate (HP 74±3bmin. EHP 83±3 b min P<0.05). Five days after delivery while systolic time intervals of the HP group (LVET = 400±3 ms; PEP= 144±2 ms) were partially returning toward the values of the normal group (LVET=410±2 ms; PEP137±2ms), those of the EHP group showed a further worsening (LVET = 397±3 ms; PEP= 151 ±2 ms). Five weeks later, most of the indices were within normal limits. It is concluded that when hypertension is superimposed on pregnancy, it causes significant changes in cardiac performance; the women who develop hypertension only during pregnancy show the greatest changes. After delivery, systolic time intervals gradually return toward normality. [ABSTRACT FROM PUBLISHER]

Twenty-three healthy males, aged 23 to 62 years, were examined by M-mode echocardiography and systolic time intervals for 3 h after (1) ethanol 1 g/kg by mouth taken over 60 minutes; (2) atenolol 100 mg by mouth; (3) ethanol (1 g/kg) + atenolol (100 mg). The peak mean blood ethanol (± s.e.) was 112 ±4 mg/100 ml in test 1 and 104 ± 7 mg/100 ml in test 3. During increasing blood ethanol, heart rate (HR), systolic blood pressure (BP), cardiac output (CO) and echocardiographic indices of left ventricular (LV) function were significantly augmented, while total peripheral resistance (TPR) decreased. During declining blood ethanol, systolic BP, L V end-diastolic and end-systolic diameters, stroke volume (SV) and circumferential wall stress were significantly reduced; echocardiographic indices of LV function were unaltered, but the pre-ejection period/LV ejection time ratio was increased, Atenolol decreased llR, systolic BP, SV, CO, and all estimates of LV function, but increased TPR. Ethanol + atenolol tended to cause smaller depressions in the indices of LV function than did atenolol alone, in spite of similar plasma atenolol concentrations (n = 6). It is concluded that ingestion of modest doses of ethanol evokes vasodilation and enhances LV function during increasing blood ethanol, and reduces LV preload and afterload during decreasing blood ethanol without impairing contractility. Social drinking and beta blockade seem not to have any harmful acute combined effects on the heart and circulation, at least in normal subjects. [ABSTRACT FROM PUBLISHER]

Left ventricular function was evaluated in 24 women who developed impaired glucose tolerance only during their pregnancy, i.e. patients with gestational diabetes. The results were compared with those of 25 normal pregnant women and with those of 17 pregnant women with clinical diabetes. The method of systolic time interval was applied. At the third trimester of pregnancy, both the women with overt diabetes and those with gestational diabetes when compared with normal pregnants subjects, had a more prolonged preejection period (PEP) and a shorter left ventricular ejection time (LVET) and, consequently, a higher PEP/LVET ratio. Five weeks after delivery, abnormalities of systolic time intervals presisted in patients with clinical diabetes, but there were no differences at this time between patients with gestational diabetes and those in the control group. It is concluded that when a cardiac load is superimposed on patients who develop diabetes only under conditions of stress, as in pregnancy (gestational diabetes), abnormalities of myocardial function appear, which revert to normal when the stressful event is removed. [ABSTRACT FROM PUBLISHER]

It has been suggested that sympathetic overactivity has a pathogenetic relevance to left ventricular hypertrophic development, even apart from its effect on and in essential hypertension. To evaluate this possibility by echocardiographic and polygraphic methods, we studied left ventricular wall thickness and function and their possible relationship to plasma renin activity and plasma catecholamines in 11 normal subjects, 13 borderline hypertensives and 11 stable hypertensives without radiological or electrocardiographic signs of left ventricular hypertrophy. Compared with normal, borderline hypertensives showed an increase in interventricular septum (IVS) thickness ( < 0.01) and IVS/posterior wall (PW) thickness ratio ( < 0.01) together with an increased supine and upright plasma norepinephrine (NE; < 0.01); there was also a decreased pre-ejection period (PEP; < 0.01), PEP/left ventricular ejection time ratio ( < 0.01) and total electromechanical systole ( < 0.05). In stable hypertensives, PW thickness was greater than it was both in normals ( < 0.01) and in borderline hypertensives ( < 0.01) and IVS thickness was higher than in normals ( < 0.05). Positive correlations between supine ( < 0.001), upright ( < 0.05) NE and both IVS thickness and IVS/PW thickness ratio were found in borderline but not in stable hypertensives. These results support the hypothesis recently put forward that IVS hypertrophy may represent an early stage of essential hypertension-induced LVH, which afterwards extends to the left PW; furthermore the results suggest that the sympathetic overactivity may play a role in the IVS hypertrophy development in borderline hypertensives. [ABSTRACT FROM PUBLISHER]

A growing body of data support the beneficial effects of angiotensin-converting enzyme inhibitors in the prevention of cardiac enlargement and improvement of left ventricular function in patients with acute myocardial infarction. However, very little information exists about the direct effect of increased afterload on cardiac performance in these patients and the possible favourable effects of angiotensin-converting enzyme inhibitors as adjunctive treatment to thrombolysis, beta-blockers and nitrates. We have, therefore, studied the effects of captopril as adjuvant therapy to thrombolysis, beta-blockers and nitrates (standard therapy) on left ventricular performance in 77 consecutive patients with uncomplicated Q-wave acute myocardial infarction, by the measurement of the pre-ejection period/left ventricular ejection time ratio before and after (0·25–0·50 mg) phenylephrine administration on the 4th and 30th post-infarction days. Patients were randomized on day 4 either to continue standard therapy alone (group 1, 35 patients) or to receive oral captopril therapy (12·5 mg t.i.d.) in addition to standard therapy (group 2, 42 patients) in a double-blind parallel study.Among the patients of group 1 there was a significant deterioration of left ventricular function after phenylephrine administration. This was shown by an increase of pre-ejection period/left ventricular ejection time ratio only in the subset of patients with ejection fraction <40%, as measured by contrast ventriculography, on both the 4th and 30th post-infarction days changing from 0·435±0·070 to 0·528±0·101, P<0·01 and from 0·404±0·098 to 0·515±0·092, P<0·02, respectively. In contrast there were no significant changes in patients with ejection fraction 40%. Among patients of group 2, phenylephrine administration induced a significant increase, only on the 4th day, in pre-ejection period/left ventricular ejection time ratio only in the subset of patients with ejection fraction <40% changing from 0·410±0·107 to 0·535±0·102, P<0·01. In the remaining patients with ejection fraction >40% there were no significant changes on either the 4th or 30th post-infarction days. Furthermore, a significant improvement was observed after phenylephrine administration in the pre-ejection period/left ventricular ejection time ratio between the 4th and 30th post-infarction days, which changed from 0·535±0·102 on day 4 to 0·368± 0·052 on day 30 (P<0·004). Also, a four-way ANOVA detected a significant reduction of heart rate in patients with ejection fraction <40< from day 4 to day 30.The results indicate that: (1) the response of pre-ejection period/left ventricular ejection time ratio after increasing afterload may be a useful non-invasive method for the detection of left ventricular dysfunction in myocardial infarction patients; and (2) captopril adjuvant therapy as compared to thrombolysis, beta-blockers and nitrates alone, after phenylephrine administration, improves the left ventricular performance response in asymptomatic Q-wave post-infarction patients and beneficially affects heart rate. This effect is most pronounced in patients with ejection fraction ≥40% whereas those with ejection fraction ≥40% do not obtain clear benefit. [ABSTRACT FROM PUBLISHER]