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PubMed2004

A comparative echocardiographic assessment of ventricular function in five species of sharks.

A comparative echocardiographic study was carried out on five shark species that differ in heart morphology and in aspects of their behavior and natural history. The study contrasted the ventricular function in the highly active mako shark (heart type IV) and four other sharks (heart type III) that differ in activity levels (i.e. the sedentary horn and swell sharks vs. the moderately active blue and smooth-hound sharks). All five species exhibited biphasic ventricular filling characterized by an early (conduit) and late (atrial systole) phase. In the mako shark, early filling was dominant as indicated by a higher early flow peak velocity, a greater early:late velocity ratio, and a greater early velocity time integral. In contrast, the late filling phase was the more important filling agent in the other species. Indices of systolic function such as ventricular ejection fraction and ventricular fractional shortening also reflect a more efficient cardiac pumping capacity in mako shark relative to the other four sharks. The comparative echocardiographic assessment of in vivo ventricular function integrates structural and functional features with shark activity level to arrive at a new perspective blending the occurrence of biphasic filling with functional concepts based on heart morphological typology and changing views regarding the role of factors such as central filling pressure and pericardial pressure on end-diastolic ventricular volume.

Animals↗
PubMed1990

Depression and recovery of right ventricular function after cardiopulmonary bypass.

Transient left ventricular dysfunction is commonly described in association with cardiopulmonary bypass (CPB). We evaluated changes in right ventricular (RV) function after elective cardiac surgery in 24 patients with normal preoperative cardiac function. In all, irrespective of distribution of coronary artery disease or use of pharmacologic support, a transient depression of RV systolic function with respect to both preinduction and initial postoperative (Postop) values occurred 262 +/- 116 min post-CPB as represented by a decrease in RV stroke volume index (25.0 +/- 1.7 vs. 33.4 +/- 1.9 ml/m2 Postop) and RV ejection fraction (31.0 +/- 2.2 vs. 45.6 +/- 2.5% Postop), and an increase in RV end-systolic and end-diastolic volume indices. This depression responded readily to pharmacologic therapy within 2 h, resolved within 24 h, and had no adverse consequences in these otherwise healthy patients. Further studies are needed to identify the cause of this phenomenon and its importance in patients with preexisting cardiac dysfunction.

Aged↗
PubMed1997

Myocardial fiber architecture and left ventricular function.

This paper develops several working hypotheses regarding the coupling between myocardial fiber architecture and left ventricular function. First, the coupling between spiral myocardial fibers and left ventricular torsional deformation and ejection fraction is examined. A proposal is then made to account for the observed change in orientation of myocardial fibers from a right hand helix in the subendocardium, through circumferential fibers in the midwall, to a left hand helix in the subepicardium in terms of a requirement for generating physiological values of both ejection fraction and pressure as well as equilibration of transmural fiber work. Finally, a pumping hypothesis is developed linking the contraction of each transmural layer of fibers to one another via collagen struts and weaves, with the resulting force transmitted to the epicardium and thence, by means of hydraulic forces associated with the constant volume property of the LV wall, to the endocardium to reduce the volume of the left ventricular chamber.

Anisotropy↗
PubMed2000

Left ventricular function and autonomic nervous system balance during two different stages of the menstrual cycle.

We studied the left ventricular function and cardiac autonomic nervous system balance variations during two different stages of the menstrual cycle. These two variables, as well as plasmatic estradiol and progesterone concentrations, were measured in a drug-free state in 20 women (29+/-6 year-old) with regular menstrual periods. A clinical evaluation, an echo-Doppler and a Valsalva manoeuvre were performed in all the patients on the third day of their menstrual cycle (follicular phase) and three days prior to their next menstrual cycle (luteinizing phase). When comparing the results obtained in these two phases, a statistically significant increase was put forward in plasmatic estradiol (50.6+/-24 vs. 127.3+/-52.8 pg/ml) and progesterone (0.37+/-0.42 vs. 11.92+/-10.8 ng/ml) concentrations, Valsalva index (1.55+/-0.22 vs. 1.67+/-0.33; P=0.044) and E/A mitral wave ratio (1.63+/-0.36 vs. 1.75+/-0.35, P=0.02). The right and left atrial volumes, left ventricular volumes and ejection fraction were similar in the two menstrual phases studied. We conclude that the autonomic nervous system balance and the left ventricular diastolic function suffer significant changes during the luteinizing phase of the menstrual cycle in normal women.

Adult↗
PubMed2005

Quantifying regional right ventricular function in tetralogy of Fallot.

Right ventricular (RV) function is notoriously difficult to quantify. Patients with tetralogy of Fallot (TOF) have decreased systolic performance. We measure regional RV performance using MRI with 1-dimensional myocardial tissue tagging. By tagging cine-MRI in two views, we measured regional shortening in 12 regions throughout the RV. We image 32 pediatric patients: 21 normal patients and 11 patients with repaired TOF. We establish a normal range for each RV region. TOF patients have decreased shortening on a region-by-region basis. We conclude that regional RV performance can be measured using this technique, and that decreased performance can be demonstrated in TOF patients.

Adolescent↗
PubMed1993

Dobutamine stress echocardiography identifies hibernating myocardium and predicts recovery of left ventricular function after coronary revascularization.

BACKGROUND: The identification of hibernating myocardium is important in selecting patients who will benefit from coronary revascularization. This study was performed to determine whether dobutamine stress echocardiography (DSE) could identify hibernating myocardium and predict improvement in regional systolic wall thickening after revascularization. METHODS AND RESULTS: DSE was performed in 49 consecutive patients with multivessel coronary disease and depressed left ventricular function. Contractile reverse during DSE was defined by the presence of two criteria: (1) improved systolic wall thickening in at least two adjacent abnormal segments and (2) > or = 20% improvement in regional wall thickening score. Postoperative echocardiograms were evaluated for improved regional wall thickening in 25 patients at least 4 weeks after successful coronary revascularization. All studies were read in blinded fashion. Contractile reserve during DSE was present in 24 (49%) of 49 patients. The presence or absence of contractile reserve on preoperative DSE predicted recovery of ventricular function in the 25 patients who underwent successful revascularization. Thus, 9 of 11 patients with contractile reserve had improved systolic wall thickening after revascularization (hibernating myocardium), whereas 12 of 14 patients without contractile reserve did not improve (P = .003). CONCLUSIONS: Dobutamine stress echocardiography provides a simple, cost-effective, and widely available method of identifying hibernating myocardium and predicting improvement in regional left ventricular wall thickening after coronary revascularization. This technique may be clinically valuable in the selection of patients for coronary revascularization.

Adult↗
PubMed1991

Assessment of systolic thickening with thallium-201 ECG-gated single-photon emission computed tomography: a parameter for local left ventricular function.

We measured left ventricular (LV) systolic thickening expressed as a systolic thickening ratio in 28 patients, using 201Tl ECG-gated SPECT. Five normals, 15 patients with prior myocardial infarction, 5 with hypertrophic cardiomyopathy, and 3 with dilated cardiomyopathy were studied. The systolic thickening ratio was calculated as [(end-systolic--end-diastolic pixel counts) divided by end-diastolic pixel counts], using the circumferential profile technique of both end-diastolic and end-systolic short axial images. Functional images of the systolic thickening ratio were also displayed with the "bull's-eye" method. The mean systolic thickening ratio thus calculated were as follows: normals, 0.53 +/- 0.05 (mean +/- 1 s.d.); non-transmural prior myocardial infarction, 0.33 +/- 0.09; transmural prior myocardial infarction, 0.14 +/- 0.05; hypertrophic cardiomyopathy in relatively nonhypertrophied areas, 0.56 +/- 0.11; hypertrophic cardiomyopathy in hypertrophied areas, 0.23 +/- 0.07; and dilated cardiomyopathy, 0.19 +/- 0.02. The systolic thickening ratio analysis by gated thallium SPECT offers a unique approach for assessing LV function.

Cardiomyopathy, Dilated↗
PubMed2005

The beneficial effect of insulin, glucose, and dipyridamole on regional left ventricular function early after acute myocardial infarction.

BACKGROUND: High-dose glucose-insulin-potassium (GIK) solution has beneficial effects on reducing mortality in acute myocardial infarction. Dipyridamole (DIP) is a powerful antioxidant and increases adenosine concentration. Experimentally, GIK and DIP have additive protective effects in ischemia-reperfusion injury. AIM: This work aims to assess the acute effects of DIP alone, GIK alone, and GIK+DIP on left ventricular function in patients evaluated early after an acute myocardial infarction. METHODS: Ten male patients (age 63+/-11 years) with uncomplicated acute myocardial infarction were evaluated within 3 days after admission. All had been treated with systemic thrombolysis and were on full therapy (including beta-blockers) at the time of testing. They underwent stress echocardiography [2D echo, with wall motion score index (WMSI) evaluated in a 16-segment model of the left ventricle, with each segment scored from 1=normal to 4=dyskinetic] during low-dose DIP alone (0.28 mg/kg in 4 min); GIK alone (4-h infusion of glucose 30%, 25 insulin units, and 40 mEq of KCl, at an infusion rate of 1.5 ml/kg/h); and GIK+DIP. RESULTS: Regional systolic function (baseline WMSI=1.69+/-0.2) improved after DIP (1.54+/-0.1), GIK (1.54+/-0.1), and, to a greater extent, after GIK+DIP (1.33+/-0.2; p<0.001 vs. baseline; p<0.05 vs. DIP; p<0.05 vs. GIK). CONCLUSION: High-dose GIK has an acute beneficial effect on regional left ventricular function in patients with acute myocardial infarction. This beneficial effect is potentiated by low-dose DIP coadministration.

Dipyridamole↗
PubMed2001

Left ventricular function and hemodynamic features of inappropriate left ventricular hypertrophy in patients with systemic hypertension: the LIFE study.

BACKGROUND: Predicted left ventricular (LV) mass for sex, height (2.7), and hemodynamic load can be used as an intrapatient reference for the observed LV mass. The ratio of observed/predicted LV mass may allow more physiologically correct comparisons of LV geometry, systolic and diastolic functions, and hemodynamics among hypertensive patients. METHODS: We studied 659 participants in the LIFE (Losartan Intervention for Endpoint Reduction in Hypertension) study with both electrocardiographic and echocardiographic LV hypertrophy (68% of the echocardiographic cohort) without previous myocardial infarction. LV mass was predicted by an equation including sex, stroke work, and height (2.7). Observed/predicted LV mass > 128% defined inappropriate LV hypertrophy (iLVH). Relative wall thickness > or = 0.43 defined concentric LV geometry. Systolic myocardial dysfunction was assessed by midwall mechanics and abnormal LV relaxation by isovolumic relaxation time (IVRT). RESULTS: Compared with patients with appropriate LV hypertrophy (aLVH), those with iLVH had higher body mass index, LV mass index, relative wall thickness, prevalences of systolic myocardial dysfunction and prolonged IVRT and lower end-systolic stress and cardiac index. Patients with eccentric iLVH had the highest wall stress and lowest ejection fraction; 43% had systolic myocardial dysfunction. Of patients with concentric iLVH, 79% had systolic myocardial dysfunction but normal ejection fraction and the lowest wall stress. Systolic myocardial dysfunction was present in 12% with concentric aLVH and none with eccentric aLVH. Prevalence of prolonged IVRT was high in all 4 groups (65% to 77%). Cardiac index was similarly lower with concentric or eccentric iLVH than with aLVH. CONCLUSIONS: Among hypertensives with LV hypertrophy, iLVH identified cardiac phenotypes with a high prevalence of myocardial systolic dysfunction.

Aged↗
PubMed1993

Repeatability of haemodynamic responses to cardiac stimulations by ambulatory monitoring of left ventricular function.

Ambulatory monitoring (VEST) of left ventricular (LV) function has been shown to be accurate and repeatable. The aim of this study was to assess VEST repeatability in the evaluation of haemodynamic responses to different cardiac stimulations. Twelve patients (all men, mean age 59 +/- 8 years) underwent two separate VEST studies 5-day apart. In both studies, LV function was continuously monitored at rest and during different cardiac stimulations: 1) changing position from supine to upright (tilt); 2) sustained isometric exercise (handgrip); and 3) sublingual administration of 5 mg of nitroglycerin (NTG). Changes from baseline to peak response (delta) in the heart rate, ejection fraction, end-diastolic volume, end-systolic volume, stroke volume and cardiac output were evaluated. Reproducibility was assessed by computing, the coefficient of repeatability. In addition, the differences between the delta values obtained with the two VEST studies were plotted against their mean. This plot allowed us to detect whether there was any relationship between the error in the measurements and the best estimate of the "true value". No statistically significant differences between the two VEST studies were found in the haemodynamic changes in heart rate, ejection fraction, end-diastolic volume, end-systolic volume, stroke volume and cardiac output induced by handgrip, tilt and NTG. For each parameter the mean difference was not significantly different from zero and no significant relationship between the error and the "true value" was observed. Our results demonstrate that VEST has a good repeatability in measuring cardiac haemodynamic responses to different types of stimulations.

Exercise↗
PubMed1995

Comparison of echocardiographic methods with magnetic resonance imaging for assessment of right ventricular function in children.

Assessment of right ventricular (RV) function is clinically relevant in the follow-up of various forms of congenital heart disease. Agreement on the value of different echocardiographic approaches for this purpose is lacking. Magnetic resonance imaging (MRI) provides dimensionally accurate RV volumes and ejection fraction. Transthoracic 2-dimensional echocardiography from 3 different views and gradient-echo tomographic MRI were performed in 16 children with congenital heart disease and 17 age-matched healthy children. RV volumes and ejection fraction were calculated with 5 mono- and biplane area-length and multiple-slice echocardiographic methods. Adequate MRI and echocardiographic apical 4-chamber images could be obtained in all 33 children. The best correlation between MRI and echocardiographic volumes was with the biplane pyramidal approximation method. End-diastolic volume by MRI was 92 +/- 27 ml: systematic difference with echocardiography was +14 +/- 16 ml (r = 0.86). End-systolic volume by MRI was 33 +/- 13 ml: systematic difference with echocardiography was -4 +/- 7 ml (r = 0.82). Ejection fraction by MRI was 65 +/- 8%: systematic difference with echocardiography was +5 +/- 7% (r = 0.72), using monoplane ellipsoid approximation. For all echocardiographic methods, significant effects of RV geometry were noted. Echocardiographic mono- and biplane area-length and multiple-slice calculations demonstrated moderate correlation and significant systematic errors compared with MRI-derived RV volumes. Echocardiographic results were influenced by RV geometry. The relatively simple monoplane area-length method provides ejection fraction results acceptable for clinical practice; results are not improved by more complex biplane and/or multislice methods.

Adolescent↗
PubMed1987

Pulsed Doppler ultrasound compared with thermodilution for monitoring cardiac output responses to changing left ventricular function.

To determine the responsiveness of the pulsed Doppler technique to pacing and drug induced changes in left ventricular function 125 simultaneous cardiac output measurements by pulsed Doppler ultrasound and thermodilution were compared in 12 patients. The Doppler velocity frequencies were analysed using a signal averaging process and the validity of this method first tested in vitro. This showed almost perfect linearity of pulsed Doppler and electromagnetic flow determinations in a test rig. Although data points showed greater scatter in the clinical study, a highly significant linear relation between cardiac output measurements by pulsed Doppler and thermodilution was confirmed by regression analysis (r = 0.88, p less than 0.001). Certain mean values for cardiac output by the two techniques differed, however, by up to 0.9 litre.min-1. Despite this, changes in cardiac output in response to pacing, inotropic stimulation with dobutamine, and vasodilatation with nitrates were directionally similar, indicating a useful role for the pulsed Doppler technique in monitoring responses to treatment in the intensive care unit. Pulsed Doppler also provided a simple measure of left ventricular contractile function. Thus the inotropic response to dobutamine produced a significant rise in peak aortic flow velocity, and this variable was unaffected by either pacing or nitrate induced vasodilatation.

Cardiac Output↗
PubMed1995

Left ventricular function on exercise after surgical treatment of small aortic annuli.

To evaluate left ventricular function during exercise after aortic annular enlargement 15 patients with either aortic (group I, n = 8) or aortomitral (group II, n = 7) annuloplasty for small aortic annuli and eight patients (group III) with standard valve replacement for aortic stenosis without small aortic annuli received gated cardiac pool imagining by technetium-99m-labelled red blood cells at rest and during exercise at a mean of 23 months after operation. Left ventricular ejection fraction, preload requitable stroke work and stroke power index (preload requitable stroke work/systolic ejection period) were measured. Compared with resting values, left ventricular performance and stroke work rate on exercise after aortic annular enlargements increased significantly, as did those after standard aortic valve replacement. These results suggest that aortic annular enlargement can be indicated for surgical treatment of valvular heart diseases associated with small aortic annuli.

Adult↗
PubMed1995

Right ventricular function evaluated by volumetric analysis during left heart bypass in a canine model of postischemic cardiac dysfunction.

Right ventricular function during left heart bypass was evaluated by volumetric analysis with a conductance catheter in 12 dogs with postischemic cardiac dysfunction. The conductance catheter was used to assess the volumetric status of the right ventricle and thereby allowed a right ventricular pressure-volume curve to be obtained, in which transient volume loading on the right ventricle was applied. The following right ventricular properties during left heart bypass were assessed and compared with properties measured without left heart bypass, by means of load-independent parameters: maximum elastance, stroke work/end-diastolic volume relation, end-diastolic pressure/volume relation, and stroke work/end-diastolic pressure relation. The stroke volume derived from the conductance catheter and the electromagnetic flow probe showed good linear correlation (r2 = 0.733 to 0.975). After initiation of left heart bypass, maximum elastance did not change significantly, although volume intercept significantly increased, from 1.2 +/- 7.3 to 3.6 +/- 7.9 ml (p < 0.05). End-diastolic pressure/volume relation was well fitted to the exponential curve (EDP = e(k1.EDV+k2)) and was shifted to the right and downward during left heart bypass; the slope k1 significantly decreased, from 0.12 +/- 0.06 to 0.10 +/- 0.07 (p < 0.01). Stroke work/end-diastolic volume relation and stroke work/end-diastolic pressure relation were closely fitted to the linear regression, and their slopes were significantly increased during left heart bypass, from 0.14 +/- 0.08 to 0.18 +/- 0.08 (p < 0.05) and from 0.22 +/- 0.15 to 0.34 +/- 0.19 (p < 0.01), respectively. These results suggest that the decompression of the left ventricle and septal shifting by left heart bypass provide good diastolic compliance and good systolic performance because of afterload unloading of the right ventricle. Thus the left heart bypass improved the overall right ventricular performance, particularly at higher end-diastolic pressures, in dogs with postischemic cardiac dysfunction.

Animals↗
PubMed1991

Monitoring right ventricular function.

A new catheter developed by Edwards Critical-Care Division measures right ventricular ejection fraction and calculates right ventricular stroke volume, end-systolic volume, and end-diastolic volume. The nurse can thus assess a patient's right ventricular function curves using the relationship between stroke volume and end-diastolic volume. This article critiques a study that used this new technology and discusses implications for clinical practice and nursing research.

Catheterization, Swan-Ganz↗
PubMed1983

Left ventricular functional alterations at rest and during submaximal exercise in patients with recent myocardial infarction.

Submaximal exercise testing with radionuclide ventriculography was performed in 117 patients prior to hospital discharge 16.7 +/- 6.7 days (SD) following acute myocardial infarction. The hypothesis tested in this study was that patients with different locations and types of infarction have different functional responses to submaximal exercise prior to discharge. The distribution of the myocardial infarctions were anterior transmural in 33, inferior transmural in 39, anterior nontransmural in 23, inferior nontransmural in 19, and indeterminant in three. Patients with transmural infarction generally had significantly larger resting left ventricular volumes at end-diastole and end-systole and lower ejection fractions and systolic blood pressure/end-systolic volume indexes than patients with nontransmural infarctions (p less than 0.05). During submaximal exercise, the change in end-systolic volume was significantly different in these two groups. When patients were separated further into anterior and inferior transmural subgroups, the patients with anterior transmural infarction had significantly lower left ventricular ejection fractions and higher right ventricular ejection fractions than the group with inferior transmural infarction (p less than 0.05). In response to exercise, the group with anterior transmural infarction had a significant decrease in left ventricular ejection fraction and a blunted systolic blood pressure/left ventricular end-systolic volume index, in comparison to patients with inferior myocardial infarction (p less than 0.05); this was the only group to have a significant increase in end-systolic volume. The group variance for the parameters studied was large, particularly during exercise when the individual responses were frequently directionally opposite from the group means. The group with anterior transmural infarction was the most homogeneous, with 26 of 33 having a directionally abnormal response to submaximal exercise. It was concluded that the group with anterior transmural infarction generally displayed the most abnormal left ventricular function. However, despite significant group differences in resting ventricular function with different infarcts, the intragroup variability at rest and in response to exercise was too great to permit an accurate prediction of the subject's resting ventricular performance or to permit a prediction of exercise response based solely on location of the infarct.

Aged↗
PubMed1984

[Systemic fibrinolytic treatment in the acute phase of myocardial infarction. Effects on coronary repermeation and left ventricular function].

Coronary angiography and 2D echocardiography were performed at the 24th hour and 21st day of acute myocardial infarction in 18 patients to study the effects of peripheral fibrinolytic therapy on coronary repermeabilisation and left ventricular function. The treatment was the same for all patients included in the study. The left ventricular ejection fraction and sequential left ventricular contractility were analysed. The first coronary angiographic control study (24th hour) showed coronary repermeabilisation in 18 cases, occurring in significantly stenosed vessels in 15 cases and in angiographically normal vessels in 3 cases, demonstrating appearances of thrombosis. Transluminal coronary angioplasty was performed in 8 cases. Coronary angiography at the 21st day showed 4 secondary occlusions in patients who had not undergone angioplasty. The comparative study of left ventricular function did not show a statistically significant difference between the 24th hour and the 21st day studies. Biochemical studies showed on early massive elevation of the specific myocardial enzyme CPK MB and a rapid fall in the fibrinolytic activity of all patients. The treatment was well tolerated and mortality was nil.

Adult↗
PubMed1995

Predictors of mortality in patients with sustained ventricular tachycardias or ventricular fibrillation and depressed left ventricular function: importance of beta-blockade.

To study prognostic factors in patients with sustained ventricular tachycardias (VT) or ventricular fibrillation (VF) complicated by left ventricular dysfunction, we evaluated the predictive value of demographic, clinical, and hemodynamic parameters for cardiac mortality and sudden cardiac death in 85 patients with VT or VF and left ventricular ejection fraction < 0.45 (mean 0.27 +/- 0.10). Patients underwent serial drug testing and received appropriate antiarrhythmic treatment, with amiodarone given as last-resort therapy. During a follow-up of 24 +/- 13 months, 23 patients died of cardiac causes, and 18 of them died suddenly. Left ventricular ejection fraction < or = 0.27 and amiodarone treatment were related to greater cardiac mortality and increased risk of sudden cardiac death, whereas beta-blockade was associated with improved survival. In the multivariate model cardiac mortality was best predicted by a left ventricular ejection fraction < or = 0.27, and absence of beta-blockade and severe left ventricular dysfunction were the strongest predictors of sudden cardiac death. We conclude that severe left ventricular dysfunction predicts increased cardiac mortality and high risk of sudden cardiac death. Moreover, beta-blocking treatment is associated with lower cardiac mortality and a reduced risk of sudden cardiac death in patients with sustained VT or VF and depressed left ventricular function. beta-Blocking agents may therefore be an important addition to conventional antiarrhythmic treatment in patients with VT or VF and left ventricular dysfunction.

Adrenergic beta-Antagonists↗