Left Ventricular Systolic Time Intervals Research Articles

Agreement of Cardiac Output Estimates between Electrical Cardiometry and Transthoracic Echocardiography in Very Preterm Infants

Introduction: The aim was to evaluate the agreement between cardiac output estimates obtained by electrical cardiometry (EC) and transthoracic echocardiography (TTE) in very preterm infants. Methods: This is a single-center prospective observational study in infants born<32 weeks gestational age within 48 h of birth. Continuous EC was recorded and simultaneous TTE obtained on day 1 and day 2 of life. Blinded TTE measurements were performed within a 10 s timeframe using beat-to-beat EC data. The primary outcome was %error of left ventricular (LV) output in milliliters per kilogram per minute (cardiac index (CI)) obtained by TTE compared to LV-CI from EC. Secondary outcome parameters were bias, %bias, limits of agreement and include measures of right ventricular (RV) output and LV systolic time intervals. Results: Analysis was performed for 34 infants (median (IQR) gestational age 29 + 0 (24 + 5 to 30 + 6) weeks + days, birthweight 960 (748 to 1,490) grams) including 44 pairwise LV output measurements on 24 participants (22 on day 1 and day 2). The %error was 54% for LV-CI (EC: 214 (38) mL/kg/min vs. TTE: 163 (47) mL/kg/min). The %error was 78% for RV-CI (EC: 213 (37) mL/kg/min vs. TTE: 241 (77) mL/kg/min). While only LV-CI values affected LV-CI bias, signal quality, heart rate, and RV-CI values affected RV-CI bias. Conclusion: EC is not interchangeable with TTE to estimate indices of LV or RV output in very preterm infants within the first 48 h postnatally. EC may not measure LV output distinctly in very preterm infants with intra- and extracardiac shunts.

Echocardiographic assessment of intravenous administration of medetomidine and xylazine hydrochloride at different sedative doses inone-humped camel calves (Camelus dromedarious).

Echocardiography illustrates a convenient and noninvasive tool for measuring cardiac output (CO) changes after administration of sedative drugs, but it is unknown in camelids practice. The aim of present study was to investigate echocardiographic effects of intravenous (IV) injection of medetomidine and xylazine in camel calves. Twenty apparently healthy immature male one-humped camel calves (Camelus dromedarious) were divided into four groups (five animals in each treatment). Medetomidine and xylazine were injected into the left jugular vein at two different doses of 10.00 and 20.00 μg kg-1 and 0.20 and 0.40 mg kg-1, respectively. Effects on some selected echocardiographic parameters were recorded at different intervals, before drug administrations (baseline) and after 3, 60 and 120 min. Data were analyzed by repeated measure, ANOVA test, then relevance and significance were taken as p ≤ 0.05. Significant decrease in fractional shortening percentage (FS%), ejection fraction percentage (EF%), stroke volume (SV), heart rate (HR) and subsequent CO were noticeable 3 min after drug administration in medetomidine high dose (MH), medetomidine low dose (ML) and xylazine high dose (XH) groups (p ≤ 0.05), furthermore at this time significant decrease in left ventricular mass (LVmass) and left ventricular systolic time intervals were seen in these groups, however, in xylazine low dose (XL) group, the lowest level of most echocardiographic parameters were detectable after 60 min. High dose IV injection of medetomidine was associated with significant decrease in most echocardiographic parameters without echocardiographic arrhythmia. Although, ML and XH groups had the same effects on echocardiographic indices but the intensity and duration were less than MH group.

Long-term Non-invasive Hemodynamic Evaluation of Left Endocardial Cardiac Resynchronization Therapy

Introduccion: La VAB es una cardiopatia congenita que puede asociarse a complicaciones aorticas y/o valvulares. Resulta importante identificar grupos de riesgo, para realizar un seguimiento mas estrecho e indicar la intervencion a tiempo. El siguiente trabajo busca analizar el impacto que tienen las caracteristicas clinicas y morfologicas valvulares en el desarrollo de disfuncion valvular aortica moderada/severa (significativa) y en la incidencia de eventos cardiovasculares mayores en adultos con VAB. Materiales y metodos: Se incluyeron pacientes consecutivos con diagnostico de VAB no sindromatica (2010-2019) en seguimiento en nuestra institucion. Se recabo informacion clinica y ecocardiografica de manera prospectiva. Se realizo analisis uni y multivariado para identificar caracteristicas clinicas y morfologicas predictoras de disfuncion valvular significativa y de eventos cardiovasculares mayores (muerte/cirugia/sindrome aortico). Una p menor 0,05 fue considerada significativa. Resultados: Se incluyeron 300 pacientes (44.3±15.3 anos, 71% hombres). La mayoria con VAB tipo I y presencia de rafe (79.6% y 77%, respectivamente). La edad media de diagnostico fue de 36.3 ±16.2 anos. Hubo 84 pacientes (31.2%) que presentaban disfuncion valvular aortica significativa al momento del inicio del estudio. Con un seguimiento a 4.9 ± 1.7 anos, 23 pacientes requirieron cirugia cardiaca (7.7%) y 3 fallecieron (1%). Al final del seguimiento 101 (33.6%) pacientes presentaban disfuncion valvular aortica significativa. La presencia de al menos 1 de los siguientes factores: prolapso valvular, calcificacion valvular aortica basal >1 y una edad > 50 anos se asocio a menor sobrevida libre de disfuncion valvular aortica significativa y de eventos mayores. Conclusiones: En nuestra cohorte, observamos una alta incidencia de eventos asociados a VAB. Dentro de las variables analizadas, la presencia de al menos 1 factor de riesgo se asocio a menor sobrevida libre de eventos mayores y disfuncion significativa a 4,9 anos.

유산소 및 저항운동 후 고교생의 동맥경직도 및 좌심실 수축시간 변화

To investigate the effects of acute aerobic and resistance exercise on the arterial stiffness and the left ventricular systolic time interval(STI), high school students(16.4±.8 yrs, n=15) were tested at resting state, immediately after exercise, recovery 1hr, and 2hr. Experiments were performed in 3 conditions; control without any handling, aerobic exercise with track running at 80% HRR, and resistance exercise with maximal repetitions at 60% RM on bench press, arm curl, leg press and leg curl. Data were analyzed by repeated two-way ANOVA on time and exercise type. As results, ABPI, baPWV and AIx, that were arterial stiffness variables, were tend to decrease at immediately after aerobic and resistance exercise, but these variables were recovered and increased than the resting values during recovery 1hr and 2hr. The patterns of STI, LVET and PEP/LVET, that were left cardiac contractility variables, were similar with those of arterial stiffness variables during recovery periods after aerobic and resistance exercise. In conclusion, the arterial stiffness was decreased at immediately after aerobic and resistance exercise, but they were increased during recovery. These changes of arterial stiffness variables seemed to be independent with left cardiac contractility variables.

Non-invasive ultrasound-based assessment of ventricular–arterial interaction in vascular Ehlers–Danlos syndrome patients

The role of ventricular–arterial hemodynamic interaction in the occurrence of arterial dissection and rupture in vascular Ehlers–Danlos syndrome (vEDS) is unknown. We recently introduced an ultrasound-based method to extract, from common carotid artery (CCA) diameter waveforms, central arterial properties and left ventricular (LV) systolic time intervals. We obtained CCA diameters, compliance and distensibility coefficients, and LV isovolumic contraction and ejection periods (ICP and EP) of 19 vEDS patients (aged 27–65 yrs) and 19 age-matched healthy controls. CCA distension and compliance tended to be lower in vEDS subjects ( p = 0.062 and p = 0.073), especially in younger patients. ICP (−12 ms) and EP (−24 ms) were shorter ( p < 0.001), while heart rate was increased (+10 bpm; p < 0.001) in vEDS. The ICP/EP ratio and estimated isovolumic d P LV/d t indicated increased LV contractility in vEDS. In conclusion, vascular EDS patients tend to have a lower CCA compliance but a normal pulse pressure, most likely reflecting reduced physical fitness.

Normal left ventricular systolic time intervals assessed by pulsed wave Doppler echocardiography in the Turkmen horse of Iran.

The Turkmen horse is one of the oldest and purest breeds in the world. There is no information with regards to the normal echocardiographic parameters of this horse regarding to cardiac diseases. Pulsed-wave (PW) Doppler echocardiography was performed on 42 clinically normal 3- to 15-year-old racing Turkmen horses. There were 26 stallions and 16 mares. The left ventricular isovolumetric contraction time, pre-ejection period (PEP), and the left ventricular ejection time (LVET), were measured, and the values of the left ventricular total electromechanical systole (LVTES) and the PEP-to-LVET ratio were calculated. The most suitable window for the measurement of the aforementioned indices in PW Doppler echocardiography was the left parasternal window using the five-chamber apical view. The following values were acquired in PW Doppler echocardiography: PEP = 0.088 ± 0.018 s; LVET = 0.445 ± 0.031 s; LVTES = 0.533 ± 0.032 s; and PEP-to-LVET = 0.199 ± 0.046. These measurements can be used in the future as standard and reference values for the evaluation of cardiovascular disorders in the Turkmen horse.

Do electrical parameters of the cardiac cycle reflect the corresponding mechanical intervals as the heart rate changes?

The evoked QT interval can be detected beat by beat through an implanted pacing system. The correlation between the right ventricular paced QT interval and the left ventricular systolic interval is not known. The aim of our study was to collect data on the correlation between QT and systolic and diastolic indexes at different heart rates in patients with dual-chamber rate-responsive pacemakers. The study involved 13 patients [67 +/- 9 years; ejection fraction (EF) 52 +/- 10%] with standard indication for dual-chamber pacing. Patients were evaluated at rest in the supine position. The AV delay was set at 130 ms, and the pacing rate was increased from 90 to 130 bpm (10 bpm steps for 3 min). At the end of each 3 min step, QT intervals were automatically evaluated in real time by means of pacemaker telemetry. We also evaluated heart performance by means of echo-2D (end-diastolic/end-systolic volumes, EF) and echo-Doppler measurements [left ventricular ejection time (LVET) and diastolic filling time (LVDFT), aortic velocity time integral, and systolic volume] and systemic arterial pressure. The QT interval progressively decreased from 330 +/- 20 to 280 +/- 10 ms as the pacing rate was increased from 90 to 130 bpm. The correlation between the QT interval and LVET as a function of the pacing rate was R(2) = 0.966, indicating a good and relatively parallel trend in these two parameters. The correlation between RR-QT (reflecting electrical diastole) and LVDFT (reflecting mechanical diastole) was R(2) = 0.975. The index LVET/QT (ratio between mechanical and electrical systole) was constant in the range 90-120 bpm, but significantly decreased at 130 bpm: the mechanical LVET shortens more than the electrical QT does at the highest heart rates. In paced patients at rest and during artificially increased heart rates, QT interval dynamics is closely correlated with changes in ejection time, thus constituting an electrical parameter of systolic time. A similar correlation exists between RR-QT, as a diastolic electrical interval, and the DFT.

Electromechanical Activation Time in the Prediction of Discharge Outcomes in Patients Hospitalized with Acute Heart Failure Syndrome

Left ventricular systolic time intervals, including pre-ejection period (PEP), ejection time (ET), and their ratio (PEP/ET), is determined by systolic and diastolic function and ventriculo-arterial coupling. We investigated the usefulness of the electromechanical activation time [(EMAT) PEP minus isovolumic contraction time] in the prediction of cardiac mortality or re-hospitalization for heart failure in patients with the acute heart failure syndrome (AHFS). A total of 45 patients (71.9±16.1 years old) hospitalized for AHFS were enrolled. Systolic time intervals and EMAT normalized by cardiac cycle length (%) were measured separately by separate automated acoustic devices. All parameters were assessed within 24 hours of admission, before discharge, and 2 weeks after discharge. During a mean follow-up of 242±156 days, 20 patients (44%) incurred adverse cardiovascular events including 18 re-hospitalizations for heart failure and 2 cardiovascular deaths. Using uni-variate Cox regression analysis, at admission %EMAT and %PEP, pre-discharge %EMAT, and post-discharge %EMAT significantly predicted post-discharge cardiovascular events with hazard ratios and 95% confidence intervals of 1.75 (1.13-2.70), 1.67 (1.02-2.70), 1.87 (1.10-3.17) and 2.50 (1.58-3.97) per 1-SD increment, respectively. The predictions remained significant after adjustment for age, sex, left ventricular ejection fraction, E/E´ by Doppler echocardiography, and serum N-terminal pro-brain natriuretic peptide. EMAT measured during the hospitalization course is useful in the prediction of cardiovascular outcomes in patients with AHFS independent of left ventricular ejection fraction, E/E´, and serum N-terminal pro-brain natriuretic peptide.

Cardiovascular impact of dobutamine in neonates with myocardial dysfunction

Objective To study effects of dobutamine on cardiac functional parameters, cerebral, mesenteric and renal blood flow in preterm neonates with myocardial dysfunction. Study design Prospective evaluation of Doppler sonographically measured left ventricular systolic time intervals, stroke volume (SV), cardiac output (CO), and blood flow parameters of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal arteries (RA), before, after 20 min and 8–10 h of dobutamine treatment in 20 neonates (gestational age 29.6 ± 4.4 weeks, birth weight 1450 ± 609 g and postnatal age 2 ± 2.1 days). Dobutamine was given in a mean dosage of 9.1 ± 1.1 μg/kg. Results After 20 min SV increased from 1.71 ± 0.5 ml to 2.12 + 0.57 ml/kg, CO from 223 ± 76 to 290 ml/kg/min. A shortening of left ventricular pre ejection period from 86 ± 12 to 66 ± 13 ms and of the ratio of pre-ejection period/ejection time from 0.52 ± 0.12 to 0.40 ± 0.11 were observed. Blood flow velocities of ACA increased after 8–10 h: peak systolic flow velocity (PSV) from 19.0 ± 6 to 29.6 ± 7.1 ms, end diastolic velocity (EDV) from 2.9 ± 2.6 to 12.7 ± 11.3 ms. PSV of SMA increased from 32.5 ± 4.7 to 49.7 ± 7.8 ms after 8–10 h, EDV from 8.9 ± 8 ms to 20.6 ± 6.1 ms. PSV of RA increased from 18.2 ± 6.1 ms to 39.9 ± 4.8 ms, EDV from 2.2 ± 1.2 to 8.2 ± 2.1 ms after 8–10 h. The pulsatility indices decreased significantly after 8–10 h: ACA from 2.3 ± 0.6 to 1.4 ± 0.5, SMA from 1.7 to 1.2 and RA from 2.57 to 1.57. Conclusion Dobutamine improves the cardiac functional parameters already after 20 min and has an influence on the blood flow parameters of ACA, SMA and RA 8–10 h after administration in neonates with myocardial dysfunction.

307 Disturbed Cardiac Functional Parameters and Blood Flow Parameters of Peripheral Arteries in Premature Sga Neonates

Top of pageAbstract Problem: Small for gestational age preterm neonates (SGA) are at higher risk for early postnatal morbidity and cardiovascular and metabolic diseases in later childhood. The aim of the prospective study was to determine the cardiac adaptation and the organ blood flow in growth retarded neonates after intrauterine hemodynamic disturbances in comparison to appropriate for gestational age preterm infants (AGA). Patients and methods: 25 AGA neonates (29.1 ± 1.4 wks, 1420 ± 243 g) and 25 small for gestational age neonates (30.1 ± 1.2 wks, 985 ± 167 g) were examined during the first five days. By Doppler sonographic measurements the cardiac left ventricular systolic time intervals, peak systolic velocities, end diastolic velocities and pulsatility indices of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal artery (RA) were investigated. Results: Significantly increased left ventricular pre ejection period was observed in SGA neonates. Systolic peak velocities and end diastolic velocities of ACA, SMA and RA were significantly decreased in SGA neonates in relationship to AGA neonates. The pulsatility indices were significantly increased in SGA neonates during the first five days. Conclusions: Disturbed left ventricular time intervals were observed as a sign of myocardial dysfunction in SGA neonates. In relationship to the diminished myocardial contractility there were demonstrated pathologically diminished blood flow parameters of peripheral vessels and an increased pulsatility caused by a vasoconstriction in the regional vascular bed. For that reason it seems possible, that the disturbed intrauterine perfusion persists into the postnatal life and could cause later cardiac and metabolic problems.

Study of systolic time interval in patients with essential hypertension by echocardiography

P-33 Key Words: Echocardiography, Essential Hypertension, Systolic Time Interval

Systolic time intervals assessed by 2‐D echocardiography and spectral Doppler in the horse

ABSTRACTIn the present study, the ‘acoustic windows’ for the measurement of the left ventricular systolic time intervals is studied by means of 2‐D echocardiography and cardiac Doppler ultrasonography, and the normal values in the horse (n = 112) are determined. The left ventricular isovolumetric contraction time, the pre‐ejection period (PEP), as well as the left ventricular ejection time (LVET) have been measured, and the values of the left ventricular total electromechanical systole (LVTES) and the PEP‐to‐LVET ratio have been calculated. It has been established that the most suitable window for the measurement of the aforementioned indices in 2‐D echocardiography is the right parasternal window in a view in short axis at the level of the cardiac base to measure the aortogram. In Doppler ultrasonography, the preferred window is the left parasternal using the five chambers apical view. The following values have been acquired: PEP = 0.071 ± 0.01 s; LVET = 0.532 ± 0.097 s; LVTES = 0.6 ± 0.1 s and PEP‐to‐LVET = 0.138 ± 0.025 measured by 2‐D echocardiography and PEP = 0.068 ± 0.009 s; LVET = 0.527 ± 0.076 s; LVTES = 0.598 ± 0.098 s and PEP‐to‐LVET = 0.131 ± 0.01 measured by Doppler ultrasonography.

A Study of Potential Toxic Effects After Repeated 10-Week Administration of a New Iron Chelator – Salicylaldehyde Isonicotinoyl Hydrazone (SIH) to Rabbits

Salicylaldehyde Isonicotinoyl Hydrazone (SIH)--a Pyridoxal Isonicotinoyl Hydrazone (PIH) analogue--is an effective iron chelator with antioxidant and antimalarial effects, as documented in numerous in vitro studies. However, no toxicological data obtained from in vivo studies have been made available yet. In this study, the potential toxic effects of repeated administration of SIH (50 mg/kg, once weekly, 10 weeks, i.p.), partially dissolved in a 10% Cremophor solution, on various biochemical, haematological, and cardiovascular parameters and on morphology of selected tissues were investigated in rabbits. The obtained values were compared with data from the control (saline, 1 ml/kg, i.v.) and the Cremophor (10% Cremophor solution, 2 ml/kg, i.p.) groups. In this study, SIH did not induced marked signs of toxicity: No premature deaths occurred, the body weight increase was comparable with the control and Cremophor groups. Only few and mild changes in some biochemical and haematological parameters could be determined, most of them were noticed also in the control or Cremophor groups. The morphological changes in the kidney were mild and did not manifest in the biochemical examination. The cardiac function was also not affected markedly--the values of left ventricular ejection fraction and systolic time interval did not differ from the values of control group. Only an increased left ventricular contractility (dP/dtmax) was noticed in the SIH group at the end of the experiment as compared to the controls (13,354+/-1191 vs. 9339+/-647 mmHg/s, resp.). These results seem to be promising from the standpoint of possible clinical use of SIH.

Dopplersonographic findings in neonates with significant persistent ductus arteriosus

The aim of the study was the description and review of a diagnostic management for treatment of patent ductus arteriosus in preterm neonates. Indomethacin, widely used to effect nonoperative closure of patent ductus arteriosus, has been implicated in vasoactive side effects and requires an accurate diagnosis. Firstly, the hemodynamic significance of the ductus arteriosus was assessed by clinical signs, such as tachycardia, disturbed microcirculation and a high difference of central and peripheral temperature. The patent ductus arteriosus was confirmed by echocardiography. The left ventricular systolic time intervals and the cerebral perfusion were obtained by pulsed doppler recordings. 48 preterm infants below 1500 g were investigated within the first 12 hours of life and during the first week. In 32 preterm neonates (67 %) a patent ductus arteriosus without hemodynamic significance and in 9 neonates a patent ductus arteriosus with hemodynamic changes was detected. In 9 neonates there were no signs of patent ductus arteriosus. Neonates with typical clinical signs of patent ductus arteriosus exhibited significantly diminished preejection time, prolonged ejection time and a decreased quotient of preejection and ejection time. We found pathologically changed parameters of anterior cerebral artery in neonates with clinical signs of patent ductus arteriosus. To judge the efficiency of the diagnostic management the groups of neonates were compared concerning the evidence of complications. Neonates with ductus arteriosus but without therapy did not reveal more pulmonary problems as well as intracerebral hemorrhages, renal or intestinal disturbances than the group of neonates with treated ductus arteriosus. Summarizing, we suggest that the described criteria are to be taken into account before treatment of ductus arteriosus in preterm neonates. In this way a wide clinical and echocardiographical investigation will be performed in risk neonates and a useless therapy can be avoided.

Cerebral blood flow velocity wave form as an indicator of neonatal left ventricular heart function

Objective: To investigate the relationship between cerebral blood flow velocity wave form (CBFV-WF) parameters and myocardial contractility indices in healthy and sick preterm and term newborns. Methods: Total group of 82 babies was divided into four subgroups: prematures with gestational age <34 weeks with ( n=20) and without ( n=14) respiratory distress syndrome (RDS) and infants with gestational age of >33 weeks with ( n=18) and without ( n=30) asphyxia. On day 1, 2, 3, 6 and 14, the acceleration time, Q(ECG)-peak(flow) time and preejection period of CBFV-WF (internal carotid artery) were measured through the anterior fontanel by Doppler ultrasonography. Simultaneously cardiac output, fractional shortening, systolic time intervals and their ratio were determined echocardiographically. Results: RDS-babies had higher cardiac output and better myocardial performance then non-RDS-babies. Asphyxiated babies had lower cardiac output as compared to healthy babies, improving over time. Correlations were found between CBFV-WF parameters and several myocardial function indicators, but preejection period of cerebral blood flow velocity correlated closest with the same period measured echocardiographically ( r=0.67, P<0.0001). Multiple linear regression revealed no influence of gestational age or clinical condition on this relationship. Assessment of agreement indicated that only substantial changes in myocardial performance could be monitored using preejection period of CBFV. Conclusion: Although a relationship was detected between the preejection period of CBFV and left ventricular systolic time interval (used as indicator of changes in left ventricular function), only rather large changes in left ventricular performance can be reliably detected using the preejection period of CBFV.

Systolic time intervals after phenylephrine administration for early stratification of patients after acute myocardial infarction

This study was designed to assess the usefulness of the changes in left ventricular (LV) systolic time intervals after phenylephrine administration for detecting hightisk patients soon after acute myocardial infarction by correlation with the angiographic and ventriculogmphic findings. The procedure was performed in 76 consecutive patients (group I) on the fourth postinfarction day and in 12 normal subjects (group II) free of coronary artery disease. In 20 patients with LV ejection fraction ≤ 40% (subgroup IA) the preejection period (PEP)/LV ejection time (ET) ratio increased from 0.410 ± 0.107 to 0.535 ± 0.102 (p = 0.01) after phenylephrine, whereas in the remaining 56 patients (subgroup IB) with LV ejection fraction >40% and in the 12 normal subjects the PEP/LVET increased nonsignificantly. Of patients with LV ejection fraction >40% a subset of 20 patients was distinguished with proximal stenosis in both left anterior descending and either a dominant right or left circumflex coronary artery (subset IB-a). In these the PEP/LVET increased from 0.347 ± 0.056 to 0.445 ± 0.019 (p = 0.0001) after phenylephrine, whereas in the remaining 36 patients (subset IB-b) without proximal lesions in 2 main arteries the PEP/LVET increased nonsignificantly. In conclusion, the PEP/LVET response to phenylephrine administration early after acute myocardial infarction is a precise, safe, noninvasive bedside method for early stratification of these patients.

Use of Doppler-derived left ventricular time intervals for noninvasive assessment of systolic function

Historically, left ventricular (LV) systolic time intervals obtained using an electrocardiogram, phonocardiogram and carotid arterial pulse tracing have been used to assess LV function noninvasively. Although these intervals can be derived from Doppler data, 1 there are few studies validating this approach. 2 The ratio of the preejection period (PEP) to LV ejection time (LVET) has provided the most useful index of systolic function. 3 In patients with systolic dysfunction, PEP lengthens due to a reduction in LV pressure development during isovolumic contraction, whereas LVET shortens due to a decrease in the extent of fiber shortening, in some cases with a reduced stroke volume. These changes cause an increase in the PEP/LVET ratio. 3 Theoretically, a ratio that also includes the isovolumic relaxation period would improve noninvasive assessment by encompassing LV pressure decay, which also is prolonged in patients with systolic dysfunction. Many patients with systolic LV dysfunction have mitral regurgitation (MR), which encompasses periods of isovolumic contraction, ejection and isovolumic relaxation. Therefore, we postulated that the ratio of LVET to MR duration would provide a useful and potentially better index of systolic function than do conventional systolic time intervals. The purpose of this study was to evaluate the accuracy of Doppler-derived time intervals, including the LVET/MR duration ratio, in assessing LV systolic function.

Impact on survival of a decade of change in the management of patients who have sustained a myocardial infarction.

The survival of 906 consecutive patients who had sustained an acute myocardial infarction was monitored between the beginning of week 2 and the end of week 52. Deaths which occurred during this period were successfully predicted in terms of just 6 features; namely the value of left ventricular systolic time intervals measured during the 1st week, the occurrence of a myocardial infarction prior to the current hospitalisation, the patient's age, the coexistence of diabetes mellitus, the presence of left or right bundle branch blocks, and the administration of a diuretic agent while the patient was in hospital. By means of stepwise linear discriminant analysis predictions of mortality among the first 302 patients based upon these 6 features were 80% specific and 63% sensitive. Prognostic features derived from the first 302 patients were then used to predict mortality among the remaining 604 patients. Observed and predicted mortalities were similar for both sets of patients. Although mortality was similar, the 604 latter patients had received a considerably more interventional style of management than patients in the former group. Possible reasons for this failure of a change of management to improve prognosis are discussed.

Cardiovascular responses to dobutamine determined by systolic time intervals in preterm infants

We investigated the effects of dobutamine therapy on myocardial function in premature infants. Left ventricular performance was assessed by measuring left ventricular systolic time intervals: rate-corrected pre-ejection period (PEPI), rate-corrected left ventricular ejection time (LVETI), and pre-ejection period to left ventricular ejection time ratio (PEP/LVET) which was obtained by echocardiography. Measurements were performed in 17 hemodynamically unstable premature infants who had an elevated PEP/LVET ratio before and 30 min after starting dobutamine infusion (10 micrograms/kg.min). Dobutamine infusion resulted in a significant decrease in PEPI (from 108 +/- 16 [SEM] to 95 +/- 17 msec; p less than .01) and in PEP/LVET ratio (from 0.55 +/- 0.16 [SEM] to 0.45 +/- 0.17; p less than .01), and in a significant increase in LVETI (from 255 +/- 15.7 [SEM] to 264 +/- 16.2 msec; p less than .01). Heart rate increased significantly from 146 +/- 17 (SEM) to 163 +/- 16 beat/min; p less than .01. Mean arterial pressure increased in 12 of 14 infants. These results show that dobutamine enhances left ventricular performance in premature infants who have depressed left ventricular function.

Hemodynamic effects of pindolol and atenolol at rest and during isometric exercise: A noninvasive study with healthy volunteers

Hemodynamic effects of intravenous and oral pindolol and atenolol were assessed in ten healthy volunteers by left ventricular echocardiography and systolic time intervals. Measurements were made at rest and during hand-grip-induced isometric exercise. Drug doses were pindolol 0.015 mg/kg intravenously and 10 mg/day orally, atenolol 0.1 mg/kg intravenously, and 50 mg/day orally. Heart rate at rest was reduced by both drugs. The reduction caused by atenolol during oral treatment was significantly greater (p less than 0.01). Intravenously only pindolol reduced mean arterial pressure. During oral treatment atenolol reduced the mean arterial pressure nonsignificantly. Both drugs lowered heart rate during isometric exercise, atenolol being significantly more effective. During oral treatment atenolol blunted the heart-rate reaction to exercise. Mean arterial pressure during isometric exercise rose slightly with both drugs after intravenous administration. During oral treatment only atenolol reduced the mean arterial pressure significantly. Intravenous atenolol reduced cardiac contractility at rest, indicated by significant decreases in fractional shortening, ejection fraction, and the mean velocity of circumferential fiber shortening. In contrast, intravenous pindolol and oral therapy with either drug did not change contractility. Intravenous atenolol raised total peripheral resistance. The preejection period/left ventricular ejection time ratio decreased with intravenous pindolol, while atenolol increased it. In conclusion, atenolol had more negative inotropic and chronotropic effects, especially after acute intravenous administration. Only atenolol reduced cardiac output and increased peripheral resistance. After repeated oral administration, these effects were less apparent.(ABSTRACT TRUNCATED AT 250 WORDS)