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PubMed1983

Rapid, semiautomated technique for estimating left ventricular volume.

A new system for rapidly quantitating left ventricular volume using two-dimensional echocardiography is tested. This system relies on a microprocessor built into a sector scanner that immediately calculates the length, area, and volume of the chamber being imaged using the mathematical model of an ellipsoid of revolution. The calculations are made after the observer superimposes a smooth calibrated ellipse outline on the endocardium imaged with the sector scanner. We report our experience with this system in 50 patients with a variety of cardiac disorders and compare the left ventricular volumes measured with those obtained using cineangiography, M-mode, and more detailed light pen tracing techniques. Correlations between volumes measured with the elliptical calipers and angiography were good (r = 0.820, SEE +/- 38.8 ml) (n = 100), but not as good as that between light pen tracing of the echo images and angiography (r = 0.847, SEE +/- 27.8 ml) (n = 22). M-mode correlated less well with angiography (r = 0.789; SEE +/- 42.1 ml) (n = 90). We conclude that the calibrated ellipse system is rapid and simple to use, while its accuracy matches previous studies using two-dimensional echocardiography to quantitate left ventricular volume.

Cardiovascular Diseases↗

PubMedDate not supplied

Real-time continuous measurement of right ventricular volume using a conductance catheter.

The authors propose using a multi-electrode conductance catheter to measure continuous right ventricular volume. True ventricular volume measurements are affected by four main sources of error. 1) field non-uniformity, 2) catheter curvature, 3) blood conductivity changes, and 4) leakage of current through surrounding tissues. Three-dimensional finite-element models were developed to investigate the effects of these sources of error and to devise schemes for correcting them. The models include an axisymmetric cylindrical model, a rectangular block model, and a heart model with left and right ventricular chambers. The heart model is built from conical primitives, with major dimensions derived from the literature. Finite-element simulations showed that volume measurements were underestimated due to field nonuniformity to as much as 1/25th actual volume in segments near the exciting electrodes. The extent of underestimation in a segment decreased with increasing distance of the segment from the exciting electrodes and increased for larger segmental volumes. Catheter curvature overestimated measured volume by as much as 4.5 times when the curvature was increased from 0.0 to 1.25 (from a straight catheter to a very curved one). The leakage of current through surrounding tissues overestimated volume by nearly 30%. The sensitivity of volume measurement to blood resistivity changes was found to be very high, at 70%. Correction factors established with the computer models compensate for field nonuniformity. Mathematical mapping of the curved catheter onto a fictitious straight catheter corrects for the catheter curvature error. Correction for both nonuniform field and catheter curvature allowed measurement of total ventricular volume with an error of 7%. Leakage current is determined by using different frequencies to build the catheter electric field and to separate tissue and blood resistance paths. Using this scheme, the percentage overestimation in volume measurement due to leakage could be determined with an accuracy of 85%. The proposed correction scheme for blood conductivity changes involves the in-vivo measurement of blood conductivity with the catheter itself. It was found that blood conductivity could be determined with insignificant error (< 0.5%) so long as the blood volume around the exciting electrodes had a radius of more than the electrode spacing.

Animals↗

PubMed1981

R-wave amplitude and left ventricular volume: changes with nitroglycerine and atrial pacing.

The relationship between R-wave amplitude and left ventricular volume was examined using two groups of patients, undergoing diagnostic cardiac catheterisation for investigation of chest pain, who had simultaneous R-wave recording and left ventricular angiography. R-wave amplitude was measured in leads 1, 2, 3 and V4-6. Left ventricular volume was altered by nitroglycerine (n = 18) and atrial pacing (n = 13). In both groups, increase or decrease in left ventricular volume was associated with a concomitant change of R-wave amplitude. We conclude that left ventricular volume is an important determinant of surface-recorded R waves with increased amplitude reflecting increased left ventricular volume and vice versa.

Angiography↗

PubMed2001

[Three-dimensional transesophageal echocardiographic measurement of left ventricular volumes using the average rotation method: comparison with the disk summation method].

OBJECTIVES: Three-dimensional(3-D) echocardiography accurately calculates left ventricular volumes without geometric assumptions. Conventional 3-D echocardiography using the disk summation method is limited in practical use because of the long analysis time. This study validated the average rotation method for rapid and accurate left ventricular volume measurement compared with the conventional disk summation method. METHODS: 3-D data acquisition using multiplane transesophageal echocardiography was performed in 13 patients. Left ventricular volumes and ejection fraction were calculated by the disk summation method with 20 parallel short-axis tomograms and by the average rotation method with 3, 6, 9 and 12 apical long-axis tomograms. RESULTS: 3-D left ventricular volumes and ejection fraction by the average rotation method in each subgroup of slice resolution had excellent correlation and close limits of agreement with those by the disk summation method. Intraobserver variability and interobserver variability were < or = 11%. With the use of three component tomograms, analysis time required for left ventricular volume measurement by the average rotation method was < or = 2 min. CONCLUSIONS: Transesophageal 3-D echocardiography using the average rotation method is a clinically useful tool for accurate and rapid measurement of left ventricular volume and function.

Echocardiography, Three-Dimensional↗

PubMedDate not supplied

[Simplified method of obtaining the correction factor for calculating ventricular volumes].

For the accurate measurement of ventricular volume it is required the obtainment of a correction factor for the magnification caused by the non-parallel X-rays and the "pincushion" distortion, which causes more magnification in the periphery than in the center of the fluoroscopic field. The Kasser and Kennedy method is based in the attainment of the relation between the actual and projected dimensions of a micrometrically calibrated grid filmed at the distance measured between the intensifier tube and the mid-thoracic line during the ventriculography. This technique is very accurate but expensive and troublesome. With the simpler catheter method it is obtained the relation between the projected and actual linear dimensions of the ventriculographic catheter inmediately before ventriculography. This study was aimed to compare the accuracy of the catheter method and two other proposed methods, in which the relation between the projected and actual dimensions were obtained by filming one central coin or five arranged through the fluoroscopic field at the distance measured between the tube and the patients during the ventriculography. These four correction factors were obtained in 15 patients undergoing a diagnostic cardiac catheterization. The catheter method showed a poor correlation with the grid method (r = 0.34), while both coin methods showed a high correlation with the grid method (r = 0.93 and 0.92, respectively). It is concluded that the catheter method is inaccurate and therefore is unwise to use it for the estimation of ventricular volumes. Because the peripheric distortion is clinically unimportant, the central coin methods is proposed as a simplified method for obtaining the magnification correction factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

PubMed1986

Ventricular volume of single ventricle with or without palliation and after corrective surgery--concept of septation procedure.

Ventricular volume measurements of single ventricle were carried out in 20 patients with or without palliation and in 2 after total correction. In the former 20 patients, 6 had a single left ventricle and 14 a single right ventricle, anatomically. Two having total correction were associated with undivided ventricle. In the 20 patients with or without palliation, ventricular end-diastolic volume ranged from 64 to 206 (115 +/- 42) percent of the sum of the normal left and right ventricular volumes. Ejection fraction of single ventricle ranged from 0.40 to 0.64 (0.55 +/- 0.06). There was no significant difference in ventricular volume and ejection fraction between patients with a single left and right ventricle. There was high correlation of ventricular volume with pulmonary to systemic blood flow ratio (r = 0.66, p less than 0.005). This indicates that systemic-to-pulmonary shunt should increase ventricular volume of single ventricle. In two patients after total correction, total ventricular volume was 136 and 166% of the sum of the normal left and right ventricular volumes. Total ejection fraction was 0.55 and 0.33 in the first and second patient, respectively. The prosthetic ventricular septum bulged toward the right ventricle during systole and this shift made the left ventricular volume increase and ejection fraction decrease. Right-to-left ventricular volume ratio at end-diastole was 0.74 and 0.67 in the first and second patient, respectively. These results suggest that 1) larger ventricular volume than the sum of the normal left and right ventricular volumes would be required for septation of single ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart Septum↗

PubMed1991

[Ventricular volume and coronary flow].

This study aimed at investigating the role of ventricular volume (VV), left ventricular pressure (LVP) and myocardial contractility in causing changes in coronary flow (CF), in the absence of autoregulation. Changes in VV and, consequently, in LVP and myocardial contractility were induced in 5 anesthetized dogs using an extracorporeal circulation including a heart-lung machine. Left VV was changed in steps of 10 ml, from a lowest value of 10 ml to a maximum value of 70 ml and back, by introducing and subtracting different volumes of water in and from a latex balloon placed in the left ventricle. In order to suppress any interference by autoregulatory mechanisms, the experimental manoeuvres were performed in the presence of complete coronary vasodilation obtained with dipyridamole. Each increase in VV was accompanied by an increase in diastolic LVP which was in turn responsible for a greater development of pressure by the myocardial contraction, thus producing an increase in systolic LVP. Then, the pressure developed by the myocardial contraction, considered as the difference between systolic and diastolic LVP, decreased when the ventricle was dilated to 60 and 70 ml. Diastolic CF decreased only starting from a ventricular volume of 60 ml, varying independently of the changes in diastolic LVP. In addition, the amplitude of the coronary flow reduction in systole was found to change together with the pressure developed by the myocardial contraction with which showed a significant linear correlation. During the reduction in VV, a progressive fall of diastolic LVP occurred without any significant difference with respect to the phase of increased volumes; on the contrary, systolic LVP, at each ventricular volume, was lower than in the previous phase. Also diastolic CF, when the volume was progressively reduced, was lower than in the previous manoeuvre. The amplitude of the systolic flow reduction and the pressure produced by the contraction both decreased when the ventricular volume was reduced showing a significant linear correlation. The reduction of the pressure produced by the contraction is likely to be due to a loss of contractility after the ventricle was expanded more than 3 times its resting volume. It is concluded that changes in ventricular pressure do not influence phasic CF directly and that diastolic CF decreases only following extreme ventricular dilation. Finally, systolic flow reduction is seen to depend on the myocardial contractility and not on the levels reached by the pressure inside the ventricle.

Animals↗

PubMed1986

Comparison of contrast x-ray biplane cineangiography and technetium-99m radionuclide scans for measurement of ventricular volumes in human autopsy hearts.

The area-length method is widely used in the determination of left ventricular volume. Although previous studies have reported that this technique overestimates true volume (TV), it is unknown whether this overestimation is the same at different volumes. In the present study, with the use of 10 postmortem human hearts, left ventricular volumes were determined by contrast x-ray biplane cine ventriculography (LVA), biplane radionuclide (LVR), and absolute-counts (LVC) technetium scans, and the results were correlated with TV. LVA correlated well with TV (r = 0.98). LVR correlated well with TV (r = 0.97), and LVR also correlated well with LVA (r = 0.96). Both area-length techniques (LVA and LVR) resulted in overestimation of TV with an upward shift of the regression line of 30.4ml +/- 3.8 (SEM) for LVA and 28.5 +/- 4.4 for LVR. The percentage of overestimation error was significantly greater at smaller left ventricular volumes (error = 33% at TV = 30ml and 10% at TV = 100ml, p less than 0.001). LVC correlated well with TV (r = 0.99), TVA, and LVR but underestimated TV. Thus left ventricular volumes can be reliably obtained from LVR and LVA by means of the area-length method and from LVC. When the area-length method is utilized, the percentage of error in the determination of left ventricular volume is proportional to 1/TV.

Angiocardiography↗

PubMed2004

Changes in ventricular volume in hydrocephalic children following successful endoscopic third ventriculostomy.

OBJECTIVE: The objective was to investigate the changes in ventricular volume in hydrocephalic children following successful endoscopic third ventriculostomy (ETV). MATERIALS AND METHODS: Using segmentation techniques, serial measurements of ventricular volume were performed using the MRI scans of 13 hydrocephalic children who had successful ETV between 1999 and 2002 to monitor ventricular response. All patients remained asymptomatic, did not require shunting and demonstrated radiological evidence of stoma patency on phase contrast cine MR, throughout the follow-up period extending from 1 to 3.5 years. There were 6 boys and 7 girls with a mean age at operation of 76 months (range 0.1-196 months). Imaging was obtained preoperatively, 1 week, 3 months, 6 months, 12 months and 24 months postoperatively. Each volume measured was divided by the corresponding average normal volume for sex and age, to calculate the "x Normal" ventricular volume (xN). The patients were divided into two groups for analysis: those children having large ventricular volumes at presentation (>5xN) and those with moderate initial volumes (<5xN). RESULTS: The mean preoperative volume was 207 cm(3) (11.9xN) while the mean volumes at 1 week, 3 months, 6 months, 12 months and 24 months were 120 cm(3) (6.7xN), 104 cm(3) (5.7xN), 119 cm(3) (6.8xN), 146 cm(3) (7.8xN) and 185 cm(3) (10.3xN) respectively, for the entire group. Nine patients had large preoperative ventricular volumes while 4 patients presented with moderate volumes. The pattern of change in ventricular size varied between the large and small volume groups. For the majority of patients presenting with large volumes (>5xN), ventricular size decreased significantly until 3-6 months following ETV, after which the volume change levelled off. In some patients, a slight increase in volume was observed after this period. Patients presenting with moderate initial volumes had a much less steep reduction in ventricular size in the 3-6 months following ETV, after which the volume appeared to stabilise or fall slightly. However, the final volume in both groups remained higher than normal, especially in the large presentation volume group (mean x N volumes at 12 months: large preoperative volume group = 9.8xN, moderate preoperative volume group = 2.4xN). CONCLUSION: In response to ETV, ventricular volume falls to a value lower than preoperatively but higher than the normalised value for age and sex. All patients appeared to have supranormal volumes in the long term, with the volume stabilising at 3-6 months. This contrasts with shunted patients who continue to exhibit declining ventricular volumes after 6 months. The observation that the final volumes are much higher than normal (especially in the large volume group) implies that the absorptive mechanism works less well in these patients in comparison to normal subjects and it thus appears that successful ETV produces a state of compensated communicating hydrocephalus. The long-term neurocognitive consequence of persistently enlarged ventricles may require further evaluation.

Adolescent↗

PubMed2005

Intraoperative assessment of right ventricular volume and function.

OBJECTIVE: Right ventricular function is an important aspect of global cardiac performance which affects patients' outcome after cardiac surgery. Due to its geometrical complexity, the assessment of right ventricular function is still a very difficult task. Aim of this study was to investigate the value of a new technique for intraoperative assessment of right ventricle based on transesophageal 3D-echocardiography, and to compare it to volumetric thermodilution by using a new generation of fast response thermistor pulmonary artery catheters. METHODS: Twenty-five patients with coronary artery disease underwent 68 intraoperative measurements by 3D-echocardiography and thermodilution simultaneously. Following parameters were analysed: right ventricular end-diastolic volume (RVEDV), end-systolic volume (RVESV) and ejection fraction (RVEF). Pulmonary, systemic and central venous pressures were simultaneously recorded. Segmentation of right ventricular volumes were obtained by the 'Coons-Patches' technique, which was implemented into the EchoAnalyzer, a multitask system developed at our institution for three-dimensional functional and structural measurements. RESULTS: Right ventricular volumes obtained by 3D-echocardiography did not show significant correlations to those obtained by thermodilution. Volumetric thermodilution systematically overestimates right ventricular volumes. Significant correlations were found between RVEF measured by 3D-echocardiography and those obtained by thermodilution (r=0. 93; y=0.2+0.80x; SEE=0.03; P<0.01). Bland-Altmann analysis showed that thermodilution systematically underestimates RVEF. The bias for measuring RVEF was +15.6% with a precision of +/-4.3%. The patients were divided into two groups according to left ventricular function. The group of patients with impaired function showed significantly lower right ventricular ejection fraction (44.1+/-4.6 vs. 55.1+/-3.9%; P<0.01). CONCLUSIONS: Three-dimensional echocardiography provides a useful non-invasive tool for intraoperative and serial assessment of right ventricular function. This new technique, which overcomes the limitations of previous methods, may offer key insights into management and outcome of patients with severe impairment of cardiac function.

Aged↗

PubMedDate not supplied

Assessment of left ventricular volume by an ambulatory radionuclide monitoring system during head-up tilt in patients with unexplained syncope: relation to autonomic activity assessed by heart rate variability.

BACKGROUND: Decreased left ventricular volume during head-up tilt plays an important role in triggering syncope in patients with neurally mediated syncope. However, precise changes in left ventricular volume during head-up tilt have not been well investigated. This study was conducted to test the hypothesis that the decline in left ventricular volume during tilt could trigger ventricular mechanoreceptor activation. METHODS AND RESULTS: To investigate the mechanisms of tilt-induced syncope, we measured the temporal changes in left ventricular volume, ejection fraction, cardiac output, and heart rate variability indices during head-up tilt in 25 patients with syncope of undetermined etiology. Eleven patients had a cardioinhibitory response (CI group), 7 patients showed a vasodepressor response (VD group), and 7 patients demonstrated a negative response (NG group). Before syncope, ejection fraction increased most in the CI group, the left ventricular end-diastolic volume declined most in the VD group (VD group, -11.0% +/- 3.3%; CI group, -2.8% +/- 4.8%; NG group, -3.4% +/- 2.2%; P <.005), and the high-frequency spectra increased most in the CI group (CI group, 25.0% +/- 21.0%; VD group, -4.1% +/- 11.7%; NG group, -5.3% +/- 12.7%; P <.01). The vasodepressor response was dependent on left ventricular volume, whereas the cardioinhibitory response was related to the vagal activity reflected by high-frequency spectra. CONCLUSIONS: The precise evaluation of left ventricular volume by an ambulatory radionuclide monitoring system combined with a heart rate variability analysis is considered useful for clarifying the pathophysiology of neurally mediated syncope.

Adult↗

PubMed1985

The significance of left ventricular volume measurement after heart transplantation using radionuclide techniques.

Multigated equilibrium blood pool scanning using Technetium 99m labeled red blood cells was used to measure left ventricular volumes in three heterotopic and one orthotopic heart transplant recipient(s). Simultaneously, an endomyocardial biopsy was performed and the degree of acute rejection was assessed by a histological scoring system. The scores were correlated to changes in ejection fraction and heart rate. Technetium 99m scanning data were pooled according to the endomyocardial biopsy score: no rejection; mild rejection; moderate rejection, and severe rejection. In each group, the median of the left ventricular volume parameters was calculated and correlated with the endomyocardial biopsy score, using a non-parametric one-way analysis of variance. A decrease in stroke volume correlated best with the endomyocardial biopsy score during acute rejection. A decrease in end-diastolic left ventricular volumes did not correlate as well. Changes in the end-systolic left ventricular volumes were not statistically significant, but using a simple correlation between end-systolic left ventricular volumes and endomyocardial biopsy the correlation reached significance. Changes in left ventricular volumes measured by Technetium 99m scanning may be useful to confirm the presence or absence of acute rejection in patients with heart grafts.

Adolescent↗

PubMed1998

Quantitation of left ventricular volumes and ejection fraction in post-infarction patients from biplane and single plane two-dimensional echocardiograms. A prospective longitudinal study of 371 patients.

AIMS: To determine whether left ventricular volumes and ejection fractions calculated from single plane two-dimensional echocardiograms using the algorithm (0.85A2L) correlate with those calculated using the biplane Simpson's method, and whether small changes in volumes and ejection fraction occurring post-infarction could be detected from single-plane as well as from biplane two-dimensional echocardiograms. METHODS AND RESULTS: Serial two-dimensional echocardiograms were obtained in 371 patients from the DEFIANT II trial a mean of 2 days, 1 week and 6 months post-infarction. Single plane volumes from the apical four chamber and apical long axis correlated closely with biplane Simpson's left ventricular volumes. Both single-plane left ventricular volumes significantly over-estimated biplane Simpson's volumes. Biplane Simpson's ejection fractions were consistently slightly under-estimated from the single-plane images. Differences between biplane Simpson's and single-plane volumes increased independently with increasing left ventricular size and distortion. The small changes in left ventricular volumes and ejection fraction over time were as reliably detected from single plane as from biplane images. CONCLUSION: Single-plane left ventricular volumes over-estimate biplane Simpson's volumes and under-estimate ejection fraction, and these discrepancies are amplified in dilated hearts with abnormal shape.

Adult↗

PubMed1991

Acute effects of delayed reperfusion on myocardial infarct shape and left ventricular volume: a potential mechanism of additional benefits from thrombolytic therapy.

The purpose of this study was to characterize the effects of late reperfusion on myocardial infarct shape and to quantitate associated changes in left ventricular volume. Reperfusion was delayed until there was no salvage of ischemic myocardium. Dogs underwent 6.5 h of left anterior descending coronary artery occlusion (n = 5) or 5.5 h of occlusion and 1 h of reperfusion (n = 5). Infarct shape was measured with pairs of ultrasonic crystals implanted circumferentially in the mid myocardium. Infarct stiffness was determined from end-diastolic pressure-segment length curves produced by aortic clamping. Left ventricular volume was measured with three pairs of endocardial ultrasonic crystals and the effect of infarct shape change on left ventricular volume was determined. Infarct size, expressed as a percent of the area at risk, was similar in reperfused (97 +/- 1%) and nonreperfused (98 +/- 1%) hearts. After coronary artery occlusion, infarct segments became akinetic and functional dilation, measured as end-diastolic ultrasonic crystal separation, increased to a similar extent in reperfused (24 +/- 7%) and nonreperfused (19 +/- 3%) hearts. In 13 additional dogs that underwent reperfusion and instrumentation with endocardial ultrasonic crystals for volume measurement, left ventricular volume increased 42 +/- 6% over the preocclusion level (p less than 0.001). Within minutes of reperfusion, the infarct stiffened, infarct dilation decreased to 1 +/- 4% over the baseline preocclusion level (p less than 0.05 vs. prereperfusion) and left ventricular volume decreased to 16 +/- 11% over the baseline level (p less than 0.01 vs. postocclusion). Thus, coronary artery reperfusion reverses initial infarct dilation. Changes in infarct dilation occur immediately after reperfusion and are accompanied by infarct stiffening and a decrease in left ventricular volume. Reperfusion can affect infarct shape and stiffness at a point in time when myocardial salvage is no longer possible.

Animals↗

PubMedDate not supplied

Rapid computed tomography technique to measure ventricular volumes in the child with suspected ventriculoperitoneal shunt failure I. Validation of technique with a dynamic phantom.

OBJECTIVES: Assessment of ventricular volume change is critical and can be difficult in the child with suspected shunt failure. Objective techniques described to measure ventricular volumes have used limited anatomic sampling or have been computationally intensive. Phantoms used to evaluate these techniques have used static volumes. The purpose of this study was to construct a computed tomography (CT) phantom to simulate changing ventricular volumes and to evaluate a new program to measure volumes. METHODS: The phantom is 5 Foley catheters embedded in gelatin. The balloons were filled and then scanned at 15-mL increments from 0-300 mL. The program measures the voxels of specified density within a larger volume created by applying a region of interest to a stacked volume. Calculated volumes and percent changes were compared with actual volumes and percent changes. RESULTS: Calculated volumes were consistently 7%-9% (mean: -7.8%) less than actual injected volumes across the entire 0- to 300-mL range. For true changes between -50% and +50%, all calculated changes were within +/-2.5% points of true percent change; for true changes between +50% and +100%, all calculated changes were within +/-5% points of true percent change. CONCLUSIONS: A dynamic CT phantom simulating changing ventricular volumes can be constructed from readily available materials. A new volumetric program accurately measures ventricular volumes and percent change from baseline across a wide range of volumes.

Cerebral Ventricles↗

PubMedDate not supplied

Determination of ventricular volume from changes in wall thickness.

A new method of measuring left ventricular volume is proposed which utilizes ventricular wall thickness at end systole and end diastole to estimate the ejection fraction. These measurements plus stroke volume allow the calculation of ventricular EDV. Although data from angiocardiographic studies have been used to validate the method it appears that the same data can be derived from ultrasound studies. The use of ultrasound methods would allow long term monitoring of ventricular volume changes during the course of a disease process. The proposed method appears to offer a more consistently accurate means of measuring EDV than previously suggested ultrasound methods. Comparison of EDV data calculated from angiographic and wall thickness measurements reveals the two methods to be statistically identical. In patients with a normal myocardium or valve lesions the correlation between the two methods is 0.97 with a standard error of 21 cc. There is a significant loss of accuracy when estimating ventricular volume in patients having diagnoses compatible with ventricular asynergy. An alternative method is suggested which may improve estimates of ventricular volume in these patients.

Cardiac Output↗

PubMed1985

Comparison of intravenous digital subtraction cineangiocardiography with conventional contrast ventriculography for the determination of the left ventricular volume at rest and during exercise.

Left ventricular volumes were determined by means of digital subtraction cineangiocardiography (DSA) which was performed in the right anterior oblique projection after contrast agent injection into the superior vena cava. Monoplane end-diastolic (EDV), end-systolic volumes (ESV), and ejection fraction (EF) were calculated using the 'area-length' method and were compared with the same parameters obtained by conventional left ventricular cineangiocardiography. A first group of 20 patients was studied at rest and a second group of 10 patients during bicycle exercise at a work load of 64 watts during 2 min, by DSA and conventional cineangiocardiography. Three different subtraction modes were evaluated: (1) mask mode subtraction (MMS), (2) time interval difference (TID) method and (3) a combination of MMS and TID called MMS + TID method. With the MMS method good correlations were obtained for EDV, ESV and EF at rest (r greater than 0.91) and during exercise (r greater than 0.91). The TID method showed only moderate correlations for patients at rest (r greater than 0.86) and during exercise (r greater than 0.79). Similar results as with MMS were achieved by the combined method (MMS + TID) at rest (r greater than 0.91) and during exercise (r greater than 0.91). Interobserver variability indicated a high reproducibility for all methods except for TID during exercise. It is concluded that DSA is an accurate technique for left ventricular volume determination not only at rest but also during exercise. The best results are obtained with MMS or MMS + TID methods, while left ventricular contour detection is easier and more convenient with MMS + TID.

Adult↗

PubMed1977

[Influence of modern inhalation anaesthetics on haemodynamics, myocardial contractility, left ventricular volumes and myocardial oxygen supply (author's transl)].

The cardiocirculatory responses to equianaesthetic concentrations (MAC 0.5 and MAC 1.0 plus 67% N2O) of halothane, methoxyflurane, enflurane and isoflurane were studied in a total of 35 closed-chest dogs during ventilation controlled to produce normocapnia. Each anaesthetic produced a dose-related decrease in mean arterial pressure and in values reflecting cardiac function. These included cardiac output, stroke volume, left ventricular max dp/dt and ejection fraction. Isoflurane seemed slightly less depressant to the heart than the other 3 anaesthetics. Total peripheral resistance remained nearly unaffected during halothane and methoxyflurane anaesthesia but decreased significantly with MAC 1.0 enflurane and isoflurane. There was no change in heart rate at low anaesthetic concentrations. The deeper levels of anaesthesia were associated with moderate increases in heart rate. In spite of the obvious depression of myocardial contractility there was a fall in pulmonary artery and left ventricular end-diastolic pressures and in left ventricular end-diastolic volumes with each of the agents. We take this as an expression of decreased ventricular filling resulted from pooling of blood in peripheral capacitive vessels. With the exception of isoflurane, each of the other three anaesthetics reduced coronary blood flow. Coronary vascular resistance was not substantially influenced by halothane and methoxyflurane, but decreased with MAC 1.0 enflurane and isoflurane. Myocardial oxygen availability was always found to be adequate. Isoflurane even produced a significant rise in coronary venous oxygen saturation indicating coronary vasodilation. Parallel with the depression in cardiac performance and blood pressure as two of the main predictors of energy demand, myocardial oxygen consumption was found to be significantly reduced by each of the anaesthetics. The ratio of the external work of the left ventricle to its oxygen consumption indicated that myocardial efficiency deterioated. The clinical implications are discussed.

Anesthetics↗