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PubMed2000

Familial aggregation of stroke volume and cardiac output during submaximal exercise: the HERITAGE Family Study.

Familial aggregation of stroke volume (SV) and cardiac output (Qc by CO2 rebreathing) at 50 Watts (W) and 60 % of maximal oxygen uptake (VO2max) as well as their changes in response to a 20-week endurance exercise training program was assessed in 99 Caucasian families who participated in the HERITAGE Family Study. In order to interpret familial influences independent of effects of age, sex, and body size (indexed by body surface area here), SV and Qc levels were adjusted for these primary parameters prior to genetic analysis within four sex-by-generation groups (the responses to training were additionally adjusted for their baseline values). Maximal heritabilities for baseline SV, Qc, and their changes in response to training during the two stages of submaximal exercise were estimated using a familial correlation model. At 50W, maximal heritabilities reached 41% and 42% for baseline SV and Qc, respectively, and were 29% and 38% for the respective responses to training. At 60% of VO2max, maximal heritabilities reached 46 % for baseline SV and Qc, and were 24% and 30% for the respective responses to training. Generally there were no meaningful differences between the maximal heritabilities at 50 W and 60% of VO2max. However, the maximal heritabilities for the baseline were slightly higher than the estimates for the changes in response to training. Based upon results arising from these non-obese, non-hypertensive, and sedentary families, we found that SV and Qc at 50 W and 60% of VO2max as well as their changes in response to the 20-week endurance exercise training were moderately heritable. Not only genetic determinants but also familial non-genetic factors might attribute to the observed patterns of familial aggregation of SV and Qc during submaximal exercise in the present study.

Adult↗
PubMed1981

The influence of ectopic beats and tachyarrhythmias on stroke volume and cardiac output.

The potentially adverse influence of premature ectopic beats or tachyarrhythmias on cardiac performance was studied by assessing the echocardiographic left ventricular stroke volume in 21 patients with cardiac rhythm disturbances. The beat to beat stroke volume correlated closely with end-diastolic volume in each patient (average R = .9). Premature ventricular contractions decreased stroke volume by an average of 48 +/- 8 ml (-71%) compared with sinus beats; whereas the postextrasystolic beats, although preceded by a pause and higher end-diastolic volume, increased stroke volume by only 16 +/- 7 ml (18%) over the sinus beats. Those postextrasystolic beats with equivalent timing and end-diastolic volume to the sinus beats had a mean stroke volume only 8 ml higher, suggesting that postextrasystolic potentiation plays only a minor role in augmenting stroke volume. Transient aberrant ventricular conduction of intermittent left bundle branch block, ectopic beats or atrial fibrillation failed to alter stroke volume. Ventricular bigeminy, trigeminy and quadrigeminy lowered cardiac output by 1.3, .9 and .7 l/min. The onset of tachyarrhythmias was oftentimes associated with a continuously changing end-diastolic volume and stroke volume, with either alternation or progressive increment of these variables. It is apparent that premature contractions decrease stroke volume by virtue of their infringement on diastolic filing, the principle beat to be determinant of stroke volume in arrhythmias being left ventricular end-diastolic volume. Since premature beats decrease stroke volume to an extent greater than postextrasystolic beats increase it, they may reduce cardiac output by a substantial degree, depending on their frequency of occurrence and degree of prematurity.

Arrhythmias, Cardiac↗
PubMedDate not supplied

The effect of body mass and temperature on the heart rate, stroke volume, and cardiac output of larvae of the rainbow trout, Oncorhynchus mykiss.

The goal of this experiment was to determine whether the type of tight supply-and-demand relationship between cardiac output and metabolic demand for O2 seen in juvenile and adult fish applies during larval development. To this end, we looked at how the heart rate, stroke volume, and cardiac output of rainbow trout (Oncorhynchus mykiss) larvae varied in response to changes in tissue mass and incubation temperature. Previous studies have shown that both factors have a profound influence on metabolic rate. Heart rate and stroke volume were estimated using videomicroscopic methods and used to calculate cardiac output at five or six approximately evenly spaced intervals between hatch (approximately 15 mg wet tissue mass) and 150 accumulated thermal units (degrees C d) posthatch (approximately 50 mg tissue mass) at 5 degrees, 10 degrees, 12 degrees, and 15 degrees C. Cardiac output (range 0.2-20 microL min(-1)) increased significantly in response to increases in both tissue mass and incubation temperature. The increase in cardiac output with tissue mass reflected significant increases in stroke volume as well as heart rate. Temperature only had a significant effect on heart rate (i.e., stroke volume was unaffected). The rate of increase in cardiac output as a result of tissue growth was significantly faster than the rate at which O2 demand increased (the allometric mass exponent [+/-SE] for cardiac output was 1.78 +/- 0.08; literature values for O2 uptake average approximately 1.0), which suggests that the cardiovascular system was less important as a means of delivering O2 to the tissues in small larvae than it was in larger larvae and in juvenile and adult fish. Direct diffusion appeared to be the primary means of O2 delivery in small larvae and embryos.

Animals↗
PubMed1984

Accuracy of absolute left ventricular volumes and cardiac output determined by radionuclide cardiography.

We determined left ventricular (LV) volumes and derived variables by gated equilibrium radionuclide imaging at rest and during exercise in 12 patients without valve disease or intracardiac shunts. LV volume was determined as the product of the background-corrected LV count rate and an individual attenuation correction factor divided by the count rate in peripheral blood. Attenuation correction was based on measurement of LV depth within the chest from an initial first pass study in the left lateral view and a linear attenuation coefficient of 0.156 cm-1 determined in phantom studies. The average LV depth was 8.0 cm (range 6.9-9.1) in agreement with an average depth measured by echocardiography of 8.2 cm (6.3-9.4), P much greater than 0.05. The correlation between radionuclide (RC) and simultaneous thermodilution (TD) measurements was for cardiac output (CO): r = 0.95; CO (RC) = 1.00 X CO (TD) + 0.10 1/min with a standard error of the estimate (SEE) of 0.79 1/min; for stroke volume (SV): r = 0.90; SV(RC) = 0.93 X SV (TD) + 5 ml; SEE = 8 ml; for end-diastolic volume (EDV): r = 0.96; EDV(RC) = 1.06 X EDV(TD) -14 ml; SEE = 27 ml; and for end-systolic volume (ESV): r = 0.98; ESV(RC) = 1.05 X ESV (TD) -6 ml; SEE = 20 ml. The interobserver variation, expressed as the coefficient of variation, was for cardiac output 6%, for stroke volume 6%, for end-diastolic volume 4%, and for end-systolic volume 5%. This method permits non-invasive determination of LV volume and total LV output per beat based exclusively on data obtained during radionuclide imaging.

Adult↗
PubMed2005

Comparison of electrical velocimetry and transoesophageal Doppler echocardiography for measuring stroke volume and cardiac output.

BACKGROUND: Impedance cardiography (ICG) has been used extensively to estimate stroke volume (SV) and cardiac output (CO) from changes of thoracic electrical bioimpedance (TEB). However, studies comparing ICG with reference methods have questioned the reliability of this approach. Electrical velocimetry (EV) provides a new algorithm to calculate CO from variations in TEB. As the transoesophageal Doppler echocardiographic quantification of CO (TOE-CO) has emerged as a reliable method, the purpose of this study was to determine the limits of agreement between CO estimations using EV (EV-CO) and TOE-CO. METHODS: Standard ECG electrodes were used for non-invasive EV-CO measurements. These were placed on 37 patients scheduled for coronary artery surgery necessitating transoesophageal echocardiography monitoring. Simultaneous EV-CO and TOE-CO measurements were recorded after induction of anaesthesia. EV-CO was calculated using the Bernstein-Osypka equation. TOE-CO was measured across the aortic valve using continuous-wave Doppler echocardiography and a triangular orifice model. RESULTS: A significant high correlation was found between the TOE-CO and the EV-CO measurements (r2=0.86). Data were related linearly. The slope of the line (1.10 (se 0.07)) was not significantly different from unity, and the point at which it intersected the ordinate (-0.46 (0.32) litre min(-1)) was not significantly different from zero. Bland-Altman analysis revealed a bias of 0.18 litre min(-1) with narrow limits of agreement (-0.99 to 1.36 litre min(-1)). CONCLUSIONS: The agreement between EV-CO and TOE-CO is clinically acceptable, and these two techniques can be used interchangeably.

Adult↗
PubMed1979

[Effect of prazosin in therapy-resistant chronic cardiac failure (author's transl)].

In addition to standard treatment with digitalis and diuretics prazosin (20 mg/d) and placebo were given to 14 patients with chronic therapy-resistant cardiac failure mainly of stage III for periods of 6 weeks each. Cardiac frequency, blood pressure, cardiac volume, pulmonary artery pressures and cardiac minute volume were assessed at rest and during physical exercise. Body weight, congestive changes in the chest radiograph, oedema and complaints were evaluated. During the acute trial using 2 mg of prazosin a significant increase of cardiac minute volume was demonstrable at rest and during exercise (2 P less than 0.05). After administration for 6 weeks cardiac minute volume increased from 3.2 to 4.0 l/min at rest and from 6.9 to 8.0 l/min during exercise (2P less than 0.005; n=12). There was a noticeable decrease of cardiac size from 1440 to 1306 ml/1.73 m2 (2 P less than 0.02). Haemodynamic improvement paralleled the decrease of complaints which was equivalent to an improvement of half to one stage of the New York Heart Association. In severe cardiac failure prazosin has thus an additional therapeutic effect beyond digitalis and diuretics.

Adult↗
PubMed1990

Iodinated contrast media effects on extravascular lung water, central blood volume, and cardiac output in humans.

Intravascular contrast media produce pulmonary edema in one rat model, but not in dogs or pigs. In humans, pulmonary edema after contrast media is rarely diagnosed, but subclinical edema could be more frequent than believed previously. Therefore, the authors prospectively studied the effects of diatrizoate (n = 5) and ioxaglate (n = 5) on extravascular lung water, central blood volume, and cardiac output in ten patients undergoing routine radiographic procedures. Variables were measured by thermal-dye dilution before and every 5 minutes after completion of the procedure for four repetitions. Extravascular lung water and central blood volume did not change significantly, indicating that pulmonary edema or pulmonary congestion did not occur. Cardiac output was elevated by 10.6% immediately after the procedure, but returned to baseline during the 10 following minutes. The authors conclude from this preliminary study in a small number of patients that intraarterial contrast media (less than 1.5 g/kg body weight of iodine) did not produce pulmonary edema or pulmonary congestion, even at a subclinical level.

Blood Volume↗
PubMed1977

Haemodynamic effects of a new anti-anginal drug, diltiazem hydrochloride.

The haemodynamic effects of a new anti-anginal drug, dilitazem HCl, were studied in 20 patients with angina pectoris. The 131I-dilution method was used. In two patients, one with atrial septal defect and the other with pulmonic regurgitation, heart catheterization was carried out. The drug exerted significant decrease in stroke volume, cardiac output, cardiac work, stroke work and cardiac output/circulating blood volume ratio. The patients who underwent direct cardiac catheterization disclosed no changes in Vmax and ejection fraction, but there were decreases in stroke volume. The decrease in cardiac work and stroke work after after diltiazem Hcl therapy was apparently due to diminution of venous return and prolongation of systemic circulation time. It is postulated that such a decrease leads to inhibition of myocardial oxygen consumption, which in turn has beneficial effects on angina pectoris.

Adult↗
PubMed2006

Measurement of cardiac ventricular volumes using multidetector row computed tomography: comparison of two- and three-dimensional methods.

This study compared a three-dimensional volumetric threshold-based method to a two-dimensional Simpson's rule based short-axis multiplanar method for measuring right (RV) and left ventricular (LV) volumes, stroke volumes, and ejection fraction using electrocardiography-gated multidetector computed tomography (MDCT) data sets. End-diastolic volume (EDV) and end-systolic volume (ESV) of RV and LV were measured independently and blindly by two observers from contrast-enhanced MDCT images using commercial software in 18 patients. For RV and LV the three-dimensionally calculated EDV and ESV values were smaller than those provided by two-dimensional short axis (10%, 5%, 15% and 26% differences respectively). Agreement between the two methods was found for LV (EDV/ESV: r=0.974/0.910, ICC=0.905/0.890) but not for RV (r=0.882/0.930, ICC=0.663/0.544). Measurement errors were significant only for EDV of LV using the two-dimensional method. Similar reproducibility was found for LV measurements, but the three-dimensional method provided greater reproducibility for RV measurements than the two-dimensional. The threshold value supported three-dimensional method provides reproducible cardiac ventricular volume measurements, comparable to those obtained using the short-axis Simpson based method.

Adult↗
PubMed1979

[Plasma renin activity, plasma volume extracellular fluid volume and cardiac output in essential hypertension (author's transl)].

The plasma renin activity (PRA), the plasma volume (PV), the extracellular fluid volume (ECV), the cardiac output and the peripheral vascular resistance (TPR) were determined in 51 patients (14 women, 37 men) with essential hypertension of varying severity. The following findings were achieved: 1. In 9 of the 51 patients with essential hypertension (approximately 18%) a low and non-sensitive PRA was detected. 2. PV, ECV, cardiac output and the calculated peripheral vascular resistance of the essential hypertensive patients with low and non-sensitive PRA did not differ significantly from those of the essential hypertensive patients with normal or elevated PRA. 3. The hypertensive patients with low and nonsensitive PRA had the highest average arterial pressure. From these findings it can be concluded that the essential hypertensive patients with low PRA are not an homogeneous group. It is assumed that in a subgroup the elevated blood pressure may be the cause of the renin suppression.

Adult↗