Differences In End-diastolic Volume Research Articles

Echocardiographic estimates of stroke volume in healthy dogs: comparability, reference intervals, and reproducibility

Introduction: This study aimed to compare estimates of stroke volume (SV) from different anatomic sites and to generate reference intervals for indices such as shunt volume (ShuntVol) or regurgitant volume (RegVol) in a large sample of healthy dogs. Animals, Materials and MethodsNinety healthy dogs underwent an echocardiogram, where SV was assessed at the level of the pulmonary valve (SVPV), aortic valve (SVAV), mitral valve (SVMV), and left ventricle using the difference in end-diastolic volume and end-systolic volume from a right parasternal long-axis four-chamber view (SVLV_RPLx) and left apical four-chamber view (SVLV_Ap4Ch). Eight dogs underwent repeated echocardiograms by the same operator on three different days and by three different operators on the same day. Bland–Altman plots and 95% reference intervals were generated. Reproducibility was described using coefficients of variation and reproducibility coefficients. ResultsMean differences (95% limits of agreement) for ShuntVol (SVPV-SVAV), RegVolLV_RPLx (SVLV_RPLx-SVAV), RegVolLV_Ap4Ch (SVLV_Ap4Ch-SVAV), and RegVolMV (SVMV-SVAV) were as follows: −0.14 (−0.72, 0.44), −0.05 (−0.59, 0.48), −0.16 (−0.71, 0.39), and 0.12 (−0.76, 1.00) mL/kg, respectively. All but RegVolLV_RPLx showed significant (P<0.01) fixed bias. Reference intervals for ShuntVol, RegVolLV_RPLx, RegVolLV_Ap4Ch, and RegVolMV were as follows: −0.85-0.64, −0.65-0.58, −0.77-0.52, and −0.91-1.06 mL/kg, respectively. Intra-operator and interoperator coefficients of variation were lowest for SVAV and highest for SVMV and SVLV_AP4Ch. ConclusionsEchocardiographic estimates of SV are not interchangeable and can exhibit wide limits of agreement. Reference intervals help provide a frame of reference to assess disease severity in dogs with a shunting lesion (ShuntVol) and mitral regurgitation (RegVol).

82 Relationship between cardiac structure and functional capacity in a fontan cohort

IntroductionFollow up of Fontan patients involves a multimodality approach including imaging to assess cardiac function and cardiopulmonary exercise testing (CPET) to assess functional capacity. Decision making, including use of device...

Comparison of 180° and 360° Arc Data Acquisition to Measure Scintigraphic Parameters from Gated Single Photon Emission Computed Tomography Myocardial Perfusion Imaging: Is There Any Difference?

Objective:The aim of the current study was to compare 180° and 360° data collection modes to measure end diastolic volume (EDV), end systolic volume (ESV) and ejection fraction (EF) values of the cardiac system by gated myocardial perfusion tomography.Methods:Thirty-three patients underwent gated myocardial perfusion tomography. Single photon emission computed tomography data of patients’ heart were acquired by 180°, 45° left posterior oblique to 45° right anterior oblique, and 360° to obtain EDV, ESV, EF and cardiac volume changes (V1, V2, V3, V4, V5, V6, V7 and V8) throughout each cardiac cycle.Results:Results of the current study indicated that there were no significant differences between 180° and 360° angular sampling in terms of measuring EDV, ESV and EF in myocardial perfusion imaging. Cardiac volume change patterns during a cardiac cycle were also similar in 360° and 180° scans. We also observed that there was no difference in EDV, ESV and EF values between the group with stress induced by exercise and the group with stress imposed by dipyridamole.Conclusion:As there is no difference between 180°and 360° cardiac scanning in terms of EDV, ESV and EF, half-orbit scan is recommended to study these cardiac system parameters because it offers more comfort to patients and a shorter scanning time.

Heterogeneous responses of systolic and diastolic left ventricular function to exercise in patients with heart failure and preserved ejection fraction.

AimsThis study aimed to evaluate ventricular diastolic properties using three‐dimensional echocardiography and tissue Doppler imaging at rest and during exercise in heart failure with preserved ejection fraction (HFpEF) patients with borderline evidence of diastolic dysfunction at rest.Methods and resultsResults obtained from 52 HFpEF patients (left ventricular ejection fraction ≥ 50%) identified on the basis of heart failure symptoms and E/E′ values between 8 and 15 were compared with those obtained in 26 control patients with no evidence of cardiovascular disease. Mitral flow patterns, tissue Doppler imaging, and volume analysis obtained by three‐dimensional echocardiography were performed at rest and during bicycle exercise. Diastolic compliance was indexed by the E/E′ ratio and left ventricular end‐diastolic volume [(E/E′)/EDV]. There were no significant differences in end‐diastolic volume (EDV), stroke volume (SV), or ejection fraction at rest between groups. In 27 of the 52 patients, E/E′ increased during exercise (11.2 ± 3.7 to 16.8 ± 10.5), driven by a failure to augment early diastole (E′). This correlated with a fall in SV and was associated with an increase in the diastolic index (E/E′)/EDV as a measure for LV stiffness (0.122 ± 0.038 to 0.217 ± 0.14/mL), indicating that impaired diastolic reserve (designated PEF‐IDR) contributed to exercise intolerance. Of the 52 patients, 25 showed no changes in E/E′ during exercise associated with a significant rise in SV and cardiac output, still inappropriate compared with controls. Despite disturbed early diastole (E′), a blunted increase in estimated systolic LV elastance indicated that impaired systolic reserve and chronotropic incompetence rather than primarily diastolic disturbances contributed to exercise intolerance in this group (designated PEF).ConclusionThree‐dimensional stress echocardiography may allow non‐invasive analysis of changes in cardiac output that can differentiate HFpEF patients with an inappropriate increase or a fall in SV during exercise. Impaired systolic or diastolic reserve can contribute to these haemodynamic abnormalities, which may arise from different underlying pathophysiologic mechanisms.

Similar effect of autologous and allogeneic cell therapy for ischemic heart disease: results from a meta-analysis of large animal studies

Introduction: In regenerative therapy for ischemic heart disease use of both autologous and allogeneic stem cells have been investigated. An important drawback of autologous cell therapy is the restricted availability, especially in the acute setting. Besides, aging and exposure to risk factors could impair the potential of autologous cells. Allogeneic cell therapy enables pre-operative production of potent cell lines, immediate availability and would allow off the shelf therapy. However, allogeneic therapy may be hampered by the risk of graft rejection, the necessity of immune suppression or even HLA matching. We performed a meta-analysis of pre-clinical data of cell therapy for ischemic heart disease to investigate whether allogeneic and autologous cell therapy results in the same effect size. Methods: A systematic search was performed in PubMed and EMBASE in order to identify publications of controlled pre-clinical trials of unmodified stem cell therapy for acute and chronic myocardial ischemia in large animal models, published untill January 2013. We used a raw difference in mean meta-analysis to summarize data for left ventricular ejection fraction (LVEF) at follow up in control and treated animals. For left ventricular end systolic volume (ESV) and left ventricular end diastolic volume (EDV), a standardized difference in mean analysis was performed. A meta-regression analysis for cell source (autologous and allogeneic), type of ischemia (permanent occlusion and ischemia/reperfusion), cell type and other clinical relevant aspects and quality aspects was conducted as well. Results: We identified 82 studies, from which data of 1415 animals were included. The meta-analysis showed a significantly difference in mean LVEF in cell treated animals compared to control animals (8.3%, SE 0.6, p <0.001). This difference in LVEF can be explained by a significant difference in EDV. There is no significant difference in mean ESV between groups. Meta-regression analysis suggested that the improvement in LVEF was greater in permanent occlusion (9.8% SE 0.8 n=786) compared with ischemia/reperfusion models (6.2% SE 1.2 n=629 p=0.004). Allogeneic (n=331) and autologous (n=981) cell therapy results in a similar difference in mean LVEF (7.3% SE 1.5 vs. 8.8% SE 0.7 respectively, p=0.3). Conclusion: Cell therapy leads to a significant improvement in LVEF of 8.3% in large animal myocardial ischemia models, compared to control. Importantly, no difference in effect size was noted between allogeneic and autologous cell therapy. These results are important in view of practical issues for future clinical trials.

Pressure overloaded right ventricles: importance of trabeculae in evaluation of RV function by CMR

Background Cardiac magnetic resonance imaging (CMR) is the preferred method to evaluate right ventricular (RV) volumes and ejection fraction. In CMR-volumetry, trabeculae and papillary muscles can be either in- or excluded from the blood volume and both methods are used throughout literature. This study aimed to determine the impact of trabeculae and papillary muscles on right ventricular (RV) volumes and function assessed by CMR in different patient groups with pressure overloaded RVs using semi-automatic software and to determine the reproducibility of this method. Methods Four groups of 20 patients (pulmonary hypertension, arterial switch operation (ASO), Tetralogy of Fallot (TOF), systemic RV) and 20 healthy subjects underwent shortaxis multislice cine CMR. End diastolic volume (EDV), end systolic volume (ESV), RV mass and ejection fraction (EF) were measured using 2 methods. First, only manual contour tracing of the endo and epicardial borders was performed thus including trabeculae in the blood volume (method 1). With method 2, trabeculae were excluded from the blood volume using semi-automatic pixel-intensity based software. Differences in EDV, ESV volumes, RVEF and RV mass after excluding trabeculae were tested using paired samples T-test. For intra- and interobserver agreement 25 datasets were re-analyzed.

Granulocyte colony‐stimulating factor attenuates left ventricular remodelling after acute anterior STEMI: results of the single‐blind, randomized, placebo‐controlled multicentre STem cEll Mobilization in Acute Myocardial Infarction (STEM‐AMI) Trial

The aim of this study was to assess the effect of granulocyte colony-stimulating factor (G-CSF) on left ventricular (LV) function and volumes in patients with anterior ST-elevation myocardial infarction (STEMI) and depressed LV ejection fraction (EF). Sixty consecutive patients with anterior STEMI, undergoing primary angioplasty percutaneous coronary intervention (PCI), with symptom-to-reperfusion time of 2-12 h and EF ≤45% after PCI, were randomized to G-CSF 5 μg/kg b.i.d. subcutaneously (n = 24) or placebo (n = 25) for 5 days, starting <12 h after PCI. The primary endpoint was an increase from baseline to 6 months of 5% in left ventricular ejection fraction (LVEF), as measured by magnetic resonance imaging (MRI). Co-primary endpoint was a ≥20 mL difference in end-diastolic volume (EDV). Infarct size and perfusion were evaluated with late gadolinium enhancement (LGE) and gated (99m)Technetium Sestamibi single-photon emission computed tomography (SPECT). Left ventricular EDV and end-systolic volume (ESV) increased from baseline to 6 months in the placebo group (81.7 ± 24.4 to 94.4 ± 26.0 mL/m(2), P < 0.00005 and 45.2 ± 20.0 to 53.2 ± 23.8 mL/m(2), P = 0.016) but were unchanged in the G-CSF group (82.2 ± 20.3 to 85.7 ± 23.7 mL/m(2), P = 0.40 and 46.0 ± 18.2 to 48.4 ± 20.8 mL/m(2), P = 0.338). There were no significant differences in EF or perfusion between groups. A significant reduction in transmural LGE segments was seen at 6 months in the G-CSF vs. placebo groups (4.38 ± 2.9 to 3.3 ± 2.6, P = 0.04 and 4.2 ± 2.6 to 3.6 ± 2.7, P = 0.301, respectively). Significantly more placebo patients had a change in left ventricular end-diastolic volume abovethe median (9.3 mL/m(2)) when reperfusion time exceeded 180 min (median time-to-reperfusion) (P = 0.0123). Severe adverse events were similar between groups. Early G-CSF administration attenuates ventricular remodelling in patients with anterior STEMI and EF ≤45% after successful PCI.

Preliminary clinical study of real-time three-dimensional echocardiographic volume-time curve in evaluating left ventricular diastolic function

The volume-time curve change in patients with normal left ventricular (LV) diastolic function and diastolic dysfunction was evaluated by real-time three-dimensional echocardiography (RT3DE). LV diastolic dysfunction was defined by E'<A' in pulse-wave tissue Doppler for inter-ventricular septal (IVS) of mitral annulus. In 24 patients with LV diastolic dysfunction, including 12 patients with delayed relaxation (delayed relaxation group) and 12 patients with pseudo-normal function (pseudo-normal group) and 24 normal volunteers (control group), data of full-volume image were acquired by real-time three-dimensional echocardiography and subjected to volume-time curve analysis. EDV (end-diastolic volume), ESV (end-systolic volume), LVEF (left ventricular ejection fraction), PER (peak ejection rate), PFR (peak filling rate) from RT3DE were examined in the three groups. Compared to the control group, PFR (diastolic filling index of RT3DE) was significantly reduced in the delayed relaxation group and pseudo-normal group (P<0.05). There were no significant differences in EDV, ESV, LVEF, PER (P>0.05). It is concluded that PFR, as a diastolic filling index of RT3DE, can reflect the early diastolic function and serve as a new non-invasive, quick and accurate tool for clinical assessment of LV diastolic function.

Factors Affecting Accuracy of Ventricular Volume and Ejection Fraction Measured by Gated Tl-201 Myocardial Perfusion Single Photon Emission Computed Tomography

The electrocardiogram-gated single photon emission computed tomography (SPECT) measurement of left ventricular end-diastolic volume, end-systolic volume and ejection fraction may contain substantial errors. We evaluated whether patient-related factors affect the accuracy of left ventricular volume and ejection fraction measured by gated Tl-201 SPECT. A total of 518 patients without perfusion defects on Tl-201 SPECT or coronary artery disease were studied. Left ventricular volume and ejection fraction were measured from echocardiography and adenosine stress/redistribution gated Tl-201 SPECT using commercially available software packages (QGS and 4D-MSPECT). We identified factors affecting the accuracy of gated SPECT via multiple linear regression analysis of the differences between echocardiography and gated SPECT. Gated SPECT analyzed with QGS underestimated end-diastolic and end-systolic volume, and overestimated ejection fraction, but 4D-MSPECT overestimated all those values (P<0.001). Independent variables associated with increasing the difference in end-diastolic volume between echocardiography and gated SPECT were decreasing left ventricular end-diastolic wall thickness, decreasing body surface area, female sex and increasing end-diastolic volume (P<0.001). Those for end-systolic volume were decreasing left ventricular end-systolic wall thickness, female sex, and decreasing end-systolic volume (P<0.001). Increasing end-systolic wall thickness, male sex and decreasing age were independent determinants associated with an increased difference in ejection fraction (P<0.001). Adenosine stress SPECT showed significantly higher end-diastolic and end-systolic volume values and a lower ejection fraction than did redistribution SPECT (P<0.001). Patient-related factors affect the accuracy of left ventricular volume and ejection fraction measured by gated Tl-201 SPECT. Modification of gated SPECT measurements by taking account of these factors would lead to reduce systemic errors.

Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function

Dual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function. Twelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction >or=50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system. In patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test). Compared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function.

LV function parameters obtained from gated myocardial SPECT imaging: a comparison of two data processing systems

Background and aim: The QGS program used to quantify left ventricular functional parameters from gated myocardial perfusion SPECT imaging (MPI) has been extensively evaluated and compared with other quantitative computer software programs. Little has been done, however, to assess the reproducibility of the QGS algorithm on different processing systems. This study was performed to evaluate results obtained with QGS using two different workstations. Methods: Gated MPIs of 50 patients were analysed. Filtered back-projection (FBP) was performed on 2 systems (Pegasys, Hermes) while iterative reconstruction (IR) was done on one system (Pegasys) and transaxial slices then transferred to Hermes. QGS was used to calculate the left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) for both reconstruction methods. Results: Mean differences for functional parameters between the systems are given in Table 1. Bland–Altman plots showed definite trends for EDV and ESV using FBP but none for IR. Excellent correlation was obtained for all parameters with both FBP and IR.Table: 1 Results of filtered back-projection and iterative reconstruction for cardiac parametersConclusion: The difference in EDV and ESV for FBP can be ascribed to reconstruction differences (e.g. filters) between the two systems. However, when IR data were analysed on the two systems, no differences in QGS results were observed.

Optimal Rotational Interval for 3-Dimensional Echocardiography Data Acquisition for Rapid and Accurate Measurement of Left Ventricular Function

Background: Prolonged 3-dimensional echocardiography (3DE) acquisition time currently limits its routine use for calculating left ventricular volume (LVV) and ejection fraction (EF). Our goal was to reduce the acquisition time by defining the largest rotational acquisition interval that still allows 3DE reconstruction for accurate and reproducible LVV and EF calculation. Methods: Twenty-one subjects underwent magnetic resonance imaging and precordial 3DE with 2° acquisition intervals. Images were processed to result in data sets containing images at 2°, 4°, 8°, 16°, 32°, and 64° intervals by excluding images in between. With use of the paraplane feature, 8 equidistant short-axis slices were generated from each data set. The suitability of these short-axis slices for manual endocardial tracing was scored visually by 4 independent experienced observers. The LVV and EF were calculated by using Simpson’s rule from 3DE data sets with 2°, 8°, and 16° intervals, and the results were compared with values obtained from magnetic resonance imaging. The probability of 3DE to detect LVV and EF differences was calculated. Results: All patients were in sinus rhythm with a mean heart rate of 72 bpm (SD ± 12). The LV short-axis images obtained with 16° rotational scanning intervals allowed LV endocardial tracing in all subjects. Good correlation, close limits of agreement, and nonsignificant differences were found between values of LVV and EF calculated with 3DE at 2°, 8°, and 16° rotational intervals and those obtained with magnetic resonance imaging. At steps of 16°, 3DE had excellent correlation (r = 98, 99, and 99), close limits of agreement (±38, ±28.6, and ±4.8), and nonsignificant differences (P =.5,.8, and.2) with values obtained from magnetic resonance imaging for calculating end-diastolic LVV, end-systolic LVV, and EF, respectively. Three-dimensional echocardiography with use of 16° rotational intervals could detect 15-mL differences in end-diastolic volume with a probability of 95%, 11-mL differences in end-systolic volume with a probability of 92%, and 0.02 differences in EF with a probability of 95%. Conclusions: The 3DE data sets reconstructed with images selected at 16° intervals from data sets obtained at 2° precordial rotational acquisition intervals allowed the generation of LV short-axis images with adequate quality for endocardial border tracing. Therefore precordial acquisition at 16° intervals would be sufficient for the reconstruction of 3DE data sets for LV function measurement. This would reduce the acquisition time while maintaining enough accuracy for clinical decision making and would thus make 3DE more practical as a routine method. (J Am Soc Echocardiogr 2000;13: 715-22.)

Independent impact of thrombolytic therapy and vessel patency on left ventricular dilation after myocardial infarction. Serial echocardiographic follow-up.

It has been shown that successful reperfusion of the infarct-related artery by thrombolysis can prevent left ventricular dilation after acute myocardial infarction; these beneficial effects were detected from several days to several months after infarction. To date, however, no study has shown that these effects can be demonstrated within hours after the onset of infarction. Furthermore, data are scarce on the independent impact of thrombolytic therapy and late vessel patency on ventricular volume and function. The aim of this study was to assess separate effects of thrombolysis and patency of the infarct-related artery on left ventricular size and function by serial two-dimensional echocardiographic examinations. We evaluated 131 consecutive patients with first acute myocardial infarction by two-dimensional echocardiography in the following sequence: days 1, 2, 3, 7, and after 3 and 6 weeks. Intravenous streptokinase was administered in 81 patients, and 50 patients were treated without thrombolysis. Left ventricular end-diastolic volume, end-systolic volume, and ejection fraction were determined from apical two- and four-chamber views using the Simpson biplane formula and normalized to body surface area. Coronary angiography was performed in 107 patients after a mean of 26.0 +/- 20.2 (mean +/- SD) days after infarction. Patency of the infarct-related artery was assessed using TIMI criteria, with 54 considered patent (TIMI 3) and 53 with TIMI grade < 3. On day 1, end-systolic volume was significantly higher in patients not receiving thrombolysis (37.7 +/- 15.3 versus 33.0 +/- 10.6 mL/m2, P = .045). End-systolic volume (ESVi) was significantly higher in patients treated without thrombolysis throughout the study, whereas significant differences in end-diastolic volume (EDVi) were detected from day 3 (P = .041) onward and in ejection fraction (EF) from day 2 (P = .025) onward, all differences becoming progressively more significant with time (6-week values: EDVi, 78.8 +/- 25.4 versus 65.9 +/- 15.7 mL/m2, P = .001; ESVi, 45.4 +/- 22.6 versus 33.9 +/- 15.1 mL/m2, P = .002; EF, 45.1 +/- 11.6% versus 50.2 +/- 10.1%, P = .018). Patients with an occluded infarct-related artery (TIMI < 3) demonstrated highly significant differences at 6 weeks compared with patients with patent vessels (EDVi, 76.8 +/- 24.7 versus 65.2 +/- 15.6 mL/m2, P = .006; ESVi, 44.6 +/- 23.3 versus 31.9 +/- 12.2 mL/m2, P = .001; EF, 45.0 +/- 11.6% versus 52.1 +/- 9.0%, P < .001), but these differences developed more slowly than that seen among the thrombolytic subgroups. Indeed, multivariate analysis demonstrated that thrombolysis was the major determinant of initial volumes (P = .08, .02, and .08 for EDVi, ESVi, and EF, respectively), while vessel patency was the overwhelming determinant of subsequent changes (P = .0033, .0002, and .0024 for EDVi, ESVi, and EF, respectively). Additionally, ventricular volumes were significantly higher and ejection fractions lower in patients with anterior versus inferior infarction, but even adjusting for these differences as well as those associated with age, sex, and initial ventricular volume, the additive and independent impact of thrombolysis and infarct vessel patency persisted. These data indicate that the beneficial effect of thrombolysis on left ventricular size and function can be demonstrated in the earliest phases of acute myocardial infarction and that subsequent changes are mediated primarily through patency of the infarct-related artery. Thrombolytic therapy and late vessel patency thus have an additive and complementary impact in reducing ventricular dilation after myocardial infarction.

MRI Evaluation of Left Ventricular Hypertrophy in a Canine Model of Aortic Stenosis

The progression of ventricular myocardial mass in nine puppies with experimental left ventricular hypertrophy and three controls was observed over a period of 7 months using magnetic resonance imaging (MRI). Left ventricular hypertrophy was created by surgically induced aortic stenosis when the puppies were 1 month old. Quantification of the progression of the left ventricular mass due to aortic stenosis as compared to the controls of similar age was then performed during the subsequent 7 months. Cardiac gated spin-echo technique was used for the imaging of the heart. Novel edge detection techniques were applied for automated identification of the border of the myocardium for measurement. Methods for correction of partial volume effect were applied in the analysis of the data. Clear-cut differences in myocardial mass (P less than .001) and in radius-to-wall thickness ratio (r/h, P less than .02) between puppies with aortic stenosis and controls were observed. The differences in end-diastolic volume between the two groups, however, were significant during the initial phase of hypertrophic compensation (P less than .001) and insignificant (P greater than .05) during the long-term phase of hypertrophic compensation. The results demonstrated that MRI is applicable in serial assessment of myocardial hypertrophy.

MRI Evaluation of Left Ventricular Hypertrophy in a Canine Model of Aortic Stenosis

The progression of ventricular myocardial mass in nine puppies with experimental left ventricular hypertrophy and three controls was observed over a period of 7 months using magnetic resonance imaging (MRI). Left ventricular hypertrophy was created by surgically induced aortic stenosis when the puppies were 1 month old. Quantification of the progression of the left ventricular mass due to aortic stenosis as compared to the controls of similar age was then performed during the subsequent 7 months. Cardiac gated spin-echo technique was used for the imaging of the heart. Novel edge detection techniques were applied for automated identification of the border of the myocardium for measurement. Methods for correction of partial volume effect were applied in the analysis of the data. Clear-cut differences in myocardial mass (P less than .001) and in radius-to-wall thickness ratio (r/h, P less than .02) between puppies with aortic stenosis and controls were observed. The differences in end-diastolic volume between the two groups, however, were significant during the initial phase of hypertrophic compensation (P less than .001) and insignificant (P greater than .05) during the long-term phase of hypertrophic compensation. The results demonstrated that MRI is applicable in serial assessment of myocardial hypertrophy.

Sequence and magnitude of ventricular volume changes in painful and painless myocardial ischemia.

Stimulation of left ventricular stretch receptors has been proposed as a possible mechanism for the occurrence of cardiac pain. Changes in left ventricular volume were continuously assessed in 12 patients during 11 spontaneous (two painful) and 12 ergometrine-induced (nine painful) ischemic attacks with a precordial scintillation probe and blood pool labeling with technetium-99m. In all ischemic episodes, spontaneous or induced, painful or painless, severe dilatation of the left ventricle was consistently observed. These changes always preceded the onset of ST segment shifts and occurred long before pain, when present. The maximum increase in end-diastolic volume was slightly greater in painful than in painless episodes, 38 +/- 8.0% versus 28 +/- 12.4%, but no significant difference was observed in the rate of volume change or in the maximum increase of end-systolic volume (133 +/- 50% and 110 +/- 27.3%), stroke volume (-28 +/- 15% and -25 +/- 12.4%), or ejection fraction (-32 +/- 8.7% and -26 +/- 6.0%). Although the maximum end-diastolic volume achieved is greater in painful episodes, this effect cannot be separated from that of duration, and, furthermore, there was no significant difference in end-diastolic volume at the moment chest pain began. Thus, in patients with angina at rest, transient asymptomatic ST segment shifts are consistently associated with large changes in left ventricular volume, similar to those observed during painful episodes. The rate and extent of acute left ventricular dilatation do not appear to be factors directly causing anginal pain.

Effect of Age on the Response of the Left Ventricular Ejection Fraction to Exercise

To assess the effects of age on the left ventricular ejection fraction (LVEF), we performed radionuclide angiocardiography at rest and during upright bicycle exercise in 77 healthy volunteers 20 to 95 years of age. Radionuclide measurements included left ventricular ejection fraction, end-diastolic volume, and regional wall motion. Age did not appear to influence any of these indexes at rest. However, during exercise the ejection fraction was less than 0.60 in 45 per cent of subjects over age 60 as compared with 2 per cent of younger subjects (P < 0.001). In addition, there was a decline in the change in LVEF (exercise LVEF minus rest LVEF) with increase in age (r = -0.71). Wall-motion abnormalities during exercise occurred with increasing frequency in patients who were 50 and older. In the older subjects these age-related changes in ejection fraction during exercise were not associated with differences in end-diastolic volume or blood pressure.