Comparison of ultrasound and cineangiographic measurements of the mean rate of circumferential fiber shortening in man

Impaired left ventricular filling in young female diabetics. An echocardiographic study

To assess left ventricular (LV) function in diabetes mellitus, M-mode echocardiograms were recorded in 36 insulin-treated diabetic women, mean age 25 +/- 6 (SD) years, and 13 healthy women of the same age. Echocardiographic tracings of the septum and LV posterior wall were digitized and continuous plots were made of LV dimension and its rate of change. The pattern of LV filling was abnormal in 19 diabetics, when the mean value +/- 2 SD in the healthy women was taken as the normal range of the indices. The most common abnormality was a prolonged rapid filling period. The LV systolic function was normal in all diabetics. Diabetics with severe microvascular complications had thicker LV walls (p less than 0.05) and smaller LV end-diastolic diameters and stroke volumes (p less than 0.01) than the healthy women. The electrocardiographic voltage was lower in the diabetic group (p less than 0.05). These studies suggest that minor abnormalities in LV function reflecting stiffness of the myocardium are common in young female diabetics, a patient group with a relatively low prevalence of coronary artery disease.

Influence of pharmacologic intervention and valvular heart disease on left ventricular ejection phase indices: a review

Echocardiography represents an established noninvasive technique to evaluate left ventricular (LV) performance. The LV ejection phase indices may be divided into three categories: (1) volume-dependent, (2) circumferential, and (3) wall thickening. Since the latter two are not volume dependent, they are clinically more useful in patients with dilated left ventricles. These parameters have limited clinical value in the presence of left-sided volume overload conditions (e g, mitral regurgitation and aortic regurgitation) since significant LV dysfunction may exist in the presence of normal ejection phase indices by echo. The echocardiogram is also a sensitive procedure to detect subtle alterations in LV function following acute or chronic interventions with various types of vasoactive and inotropic drugs.

Phenotypic spectrum and clinical characteristics of apical hypertrophic cardiomyopathy: multicenter echo-Doppler study

OBJECTIVES

The aim of this study was to define the phenotypic spectrum of apical hypertrophic cardiomyopathy (ApHCM) and clinical characteristics pertaining to identified subtypes.

METHODS

In 182 consecutive ApHCM patients (58.9 +/- 11.2 years; 142 men) with left ventricular ejection fraction > or =50%, we measured end-diastolic wall thickness of all 16 left ventricular segments to determine patterns of hypertrophy. Echo-Doppler parameters, electrocardiography patterns, and clinical findings were analyzed.

RESULTS

ApHCM was classified into three types as pure focal (n = 81), pure diffuse (n = 70) and mixed type (n = 31) according to patterns of hypertrophy. Incidence of atrial fibrillation (5% for pure focal vs. 11% for pure diffuse vs. 23% for mixed type, p < 0.05) and left atrial volume index (30.9 +/- 11.8, 35.7 +/- 14.8, and 41.3 +/- 15.9 ml/m(2), respectively, p < 0.001) were significantly different among subtypes. Peak systolic (6.6 +/- 1.0 vs. 6.3 +/- 1.2 vs. 5.9 +/- 1.1 cm/s, respectively, p < 0.05), diastolic (5.1 +/- 1.8 vs. 5.0 +/- 1.2 vs. 4.1 +/- 1.3 cm/s, respectively, p < 0.05) mitral annular velocity, E/E' (13.3 +/- 4.2 vs. 13.7 +/- 5.4 vs. 16.1 +/- 6.1, respectively, p < 0.05) were also significantly different.

CONCLUSIONS

ApHCM contains three morphologically distinct phenotypes and detailed subtyping is important in the prediction of development of atrial fibrillation, left atrial volume index and left ventricular longitudinal function.

Influence of fluid volume variations on the calculated value of the left ventricular mass measured by echocardiogram in patients submitted to hemodialysis

The left ventricular mass (LVM) measurement is of major importance for renal patients, as ventricular hypertrophy is an important prognostic index. The echocardiogram of the ventricular mass is larger before than it is after hemodialysis, which can confuse data interpretation. The aim of this work is to study the influence of alterations in fluid volume on the variations in measurements of ventricular mass observed during the course of a hemodialysis. Sixteen patients with chronic renal insufficiency in hemodialysis were evaluated at the Dialysis Unit of the University Hospital-UNESP, Botucatu, São Paulo State. The left ventricular mass was calculated from echocardiograms taken before and after hemodialysis and simultaneous ultra-filtration (12 patients: UF GROUP) and before and after hemodialysis isovolemic phase with sequential ultra-filtration (10 patients: ISO GROUP). Six of these patients were submitted to measurements of left ventricular mass before and after hemodialysis in both isovolemic and simultaneous ultra-filtration procedures. In the UF group, there was significant reduction in the following parameters before and after dialysis: diastolic diameter from 54.0 +/- 6.0mm to 45.6 +/- 7.6mm; left ventricular mass from 342 +/- 114 g to 265 +/- 117 g; and its respective index (IMVE) from 214 +/- 68 g/m2 to 168 +/- 71 g/m2. The ISO group showed no statistically significant variation. The behavior of the variables of six patients submitted to both observations confirm these results. In conclusion, the variations in echocardiogram measurements of the left ventricula mass relating to hemodialysis appear to be induced by alterations of the volemic condition.

Association of varicella, myocarditis, and congestive cardiomyopathy

A retrospective study of children dying with active varicella revealed 11 of 17 cases who had unsuspected interstitial myocarditis at the time of their death. In addition, a prospective study of 6 children, consecutively admitted to the hospital with active varicella, were evaluated for evidence of cardiac dysfunction by echocardiography, ECG, and serum enzyme levels. All 6 children had Reye's syndrome in association with active varicella. Evidence of myocardial involvement, consistent with acute congestive cardiomyopathy, was documented in 4 of the 6 children. This study suggests that the heart is commonly involved in varicella infections and that cardiac involvement should be considered in children with this disease.

Subendocardial motion in hypertrophic cardiomyopathy: assessment from long- and short-axis views by pulsed tissue Doppler imaging

BACKGROUND

Tissue Doppler imaging (TDI) is a recently developed technique that allows the instantaneous measurement of intrinsic regional myocardial motion velocity. Pulsed TDI is capable of separately assessing left ventricular (LV) regional motion velocity caused by circumferential and longitudinal fiber contraction. This particular feature of function is still controversial in patients with hypertrophic cardiomyopathy (HC).

METHODS

To better characterize intrinsic circumferential and longitudinal LV systolic myocardial function in HC, we used pulsed TDI to measure short- and long-axis LV motion velocities, respectively. The subendocardial motion velocity patterns at the middle of the LV posterior wall (PW) and ventricular septum (IVS) in LV parasternal and apical long-axis views were recorded by pulsed TDI in 19 patients with nonobstructive HC and in 21 normal controls (NC).

RESULTS

Peak short- and long-axis systolic subendocardial velocities in both the LV PW and IVS were significantly smaller in the HC group than in the NC group, and the time to peak velocity was significantly delayed. Furthermore, peak PW systolic velocity was significantly greater along the long axis than along the short axis in the NC group (8.8 +/- 1.5 cm/s vs 8.2 +/- 1.4 cm/s, P <.05), whereas the opposite was observed in the HC group (6.1 +/- 1.2 cm/s vs 7.5 +/- 1.0 cm/s, P <.0001). No significant differences were found in either group between the long- and short-axis IVS velocities (HC: 5.9 +/- 1.4 cm/s vs 5.5 +/- 1.3 cm/s; NC: 7.8 +/- 1.3 cm/s vs 7.9 +/- 1.6 cm/s).

CONCLUSIONS

By using the capability of pulsed TDI for the evaluation of intrinsic myocardial velocity instantaneously in a specific region and direction, we found impairment of LV myocardial systolic function in patients with HC not only in the hypertrophied IVS but also in the nonhypertrophied LV PW. We also found a greater decrease in LV PW velocities along the long axis than the short axis, suggesting greater impairment of long-axis contraction in patients with HC. Because our HC patients did not appear to have excessive intracavitary pressure, these results suggest that the relatively normal-appearing PW is directly affected by the HC pathologic process.

Hemodynamic and electrophysiologic effects of acute chocolate ingestion in young adults

The purpose of this study was to determine the hemodynamic and electrophysiologic effects of acute chocolate, and hence theobromine, ingestion on the hearts of young adults. Theobromine was not found to have any cardiovascular effects on subjects in this study.

Assessment of left ventricular systolic wall motion velocity with pulsed tissue Doppler imaging: comparison with peak dP/dt of the left ventricular pressure curve

To assess the usefulness of the tissue Doppler imaging variables for the evaluation of left ventricular (LV) systolic function, we compared variables obtained by the pulsed Doppler method with the LV ejection fraction (%EF) and the maximum value for the first derivative of LV pressure (peak dP/dt). We examined 65 patients, including 15 patients with noncardiac chest pain, 15 with ischemic heart disease, 15 with dilated cardiomyopathy, 10 with hypertensive heart disease, and 10 with asymmetric septal hypertrophic cardiomyopathy. The subendocardial systolic wall motion velocity patterns were recorded for LV posterior wall and ventricular septum in the parasternal LV long-axis view. The peak dP/dt was significantly lower in the hypertensive heart disease, hypertrophic cardiomyopathy, and dilated cardiomyopathy groups. The peak systolic velocity was lower and the time from the electrocardiographic Q wave to the peak of the systolic wave for the posterior wall was longer in the hypertensive heart disease (5.9 +/- 0.5 cm/sec and 215 +/- 21 msec, respectively), hypertrophic cardiomyopathy (6.2 +/- 0.9 cm/sec and 217 +/- 17 msec, respectively), and dilated cardiomyopathy (5.2 +/- 0.8 cm/sec and 235 +/- 26 msec, respectively) groups than in the noncardiac chest pain (7.7 +/- 0.9 cm/sec and 187 +/- 24 msec, respectively) and the ischemic heart disease (7.6 +/- 0.8 cm/sec and 184 +/- 22 msec, respectively) groups. In all groups, the peak systolic velocity and the time from the electrocardiographic Q wave to the peak of the systolic wave for the posterior wall correlated directly and inversely, respectively, with the %EF (r = 0.59, p < 0.0001; r = -0.59, p < 0.0001) and the peak dP/dt (r = 0.75, p < 0.0001; r = -0.68, p < 0.0001). Both tissue Doppler variables for the ventricular septum did not correlate with the %EF but roughly correlated with peak dP/dt. We conclude that the systolic LV wall motion velocity parameters obtained by pulsed tissue Doppler imaging may be useful for noninvasive evaluation of global LV systolic function in patients with no regional asynergy.

Hemodynamic and neurohormonal effects of flosequinan in patients with heart failure

In a double-blind, placebo-controlled study, the central and peripheral hemodynamic effects of 100 mg oral flosequinan and the impact of this drug on neurohormonal activation were noninvasively evaluated in 18 patients with congestive heart failure, after the first administration and after 10 days of treatment. No significant hemodynamic and neurohormonal changes were observed after acute administration. After 10 days, flosequinan produced central and peripheral hemodynamic improvement characterized by an increase in left ventricular circumferential fiber shortening velocity (+12%), a decrease in total systemic resistance (-36%), and an increase in leg blood flow (+37%). No significant changes were observed in heart rate and arterial pressure in patients receiving flosequinan, though a slight increase in heart rate (+17%) was recorded. Despite these favorable hemodynamic effects, flosequinan significantly increased plasma norepinephrine (+38%) and plasma renin activity (+13%) after 10 days of treatment. Thus, the beneficial central and peripheral hemodynamic effects of flosequinan are accompanied by activation of the sympathetic and reninangiotensin systems. This might be related to the unfavorable effects of the drug on survival in patients with heart failure.

Short- and long-term variability of echocardiographic stress-velocity indexes of cardiac function in a pediatric population

This study determined the short- and long-term variability of stress-velocity relationships at end systole and peak systole. A prospective study during the short term (0 to 15 and 0 to 30 minutes) and long term (0 to 1 and 0 to 12 months) was performed calculating variability by the limits of agreement method. The study was performed in a tertiary-care pediatric echocardiographic laboratory. Twenty-five normal children underwent repeat testing as described. Standard blood pressure, carotid pulse tracing, and M-echocardiography of the left ventricle was performed at the intervals described. The rate-corrected mean velocity of fiber shortening (MVCFC), echocardiographic stress at end systole (SES), and echocardiographic stress at peak systole (SPS) were calculated for all recordings. The slopes of MVCFC-SES and MVCFC-SPS were determined by regression and plotted. With these slopes, the second and third stress values were normalized to the first stress value for the short and long term. The differences in normalized MVCFC and MVCFC (delta MVCFC) for 15 to 0 minutes, 30 to 0 months, 1 to 0 month, and 12 to 1 month were obtained for both SES and SPS, and 95% limits of agreement were estimated. The mean delta MVCFC for SES and SPS for the short and long term were not different from 0 or each other, indicating no bias. The 95% limits of agreement of delta MVCFCs (i.e., variability for SES at 15 to 0 minutes, 30 to 0 minutes, 1 to 0 month, and 12 to 0 month) were +/- 0.18, +/- 0.24, +/- 0.34, and +/- 0.27, respectively, and for SPS +/- 0.18, +/- 0.24, +/- 0.33, and +/- 0.28. Variability showed an increasing trend with time but was significant only from 15 to 0 minutes and 1 to 0 month (p = 0.006). This study has established short- and long-term variability in the stress-velocity relationship that is essential for monitoring acute and chronic changes in ventricular contractility in an individual patient.

Nonlinearity of the left ventricular end-systolic wall stress-velocity of fiber shortening relation in young pigs: a potential pitfall in its use as a single-beat index of contractility

OBJECTIVES

We sought to evaluate in the young heart the primary assumptions on which the current use of the mean "velocity of fiber shortening corrected for heart rate" as a noninvasive index of contractility are based.

BACKGROUND

End-systolic wall stress-velocity of fiber shortening relation has been applied as a single-beat, load-independent index of contractility in children. This use is based on poorly validated assumptions of linearity, parallel shifts with changing contractile state and inotropic sensitivity of the end-systolic wall stress-velocity of fiber shortening relation.

METHODS

In eight anesthetized young piglets, 5F mciromanometric catheters were placed in the ascending aorta and balloon occlusion catheters in the descending aorta. End-systolic wall stress and velocity of fiber shortening were calculated from aortic pressure and M-mode echocardiography under six conditions: in three contractile states 1) baseline, 2) increased contractility during dobutamine infusion (10 micrograms/kg per min), and 3) decreased contractility after propranolol injection (1 mg/kg), each at two afterload states (normal and increased load by partial aortic occlusion).

RESULTS

Dobutamine increased and propranolol decreased afterload-matched velocity of fiber shortening corrected for heart rate significantly to 140% and 77% of baseline, respectively. However, the slope of end-systolic wall stress-velocity of fiber shortening relation was much greater (251% of baseline) during dobutamine infusion, which also significantly decreased wall stress, and was much less (27% of baseline) after propranolol injection, which increased wall stress.

CONCLUSIONS

The velocity of fiber shortening corrected for heart rate did change predictably with changes in contractility and as such can be used noninvasively in the temporal evaluation of individual patients undergoing therapeutic interventions or to define the natural history of a disease process. However, the relation on which it is based is not defined by parallel straight lines across contractile states, so that abnormal single point measurements may reflect only the nonlinearity of the relation rather than abnormalities in contractility. Thus, we recommend that the end-systolic wall stress-velocity of fiber shortening relation should not be used as a single-beat index of contractility.

Analysis of heart morphology and function following erythropoietin treatment of anemic dialysis patients

In a two-way study, we treated renal anemia in chronic hemodialysis patients with recombinant human erythropoietin (rh-EPO) and followed heart morphology and function dynamics by echocardiography. Thirty-eight patients were randomly divided in two equal groups: the therapy group, treated with rh-EPO for 24 months, and the control group, not treated during the first 12 months and treated with rh-EPO during the second 12 months. Anemia was corrected, and hematocrit was maintained between 30 and 35 vol% by subcutaneous rh-EPO administration. Echocardiographic assessment was performed at the end of the untreated control phase and was repeated after 12 months of rh-EPO treatment in the control group and after 12 and 24 months of treatment in the therapy group. The results revealed significant morphologic, hemodynamic, and eventually functional changes. After 12 months of rh-EPO treatment, the end-diastolic volume (EDV) decreased from 135.8 +/- 23.7 to 109.8 +/- 25.3 ml, p < 0.001; stroke volume (SV) from 91.9 +/- 17.6 to 71.3 +/- 12.4 ml, p < 0.001; left ventricular mass-Devereux (LVMD) from 297.2 +/- 57.8 to 218.0 +/- 50.4 g, p < 0.01; cardiac output (CO) from 7,279 +/- 1,932 to 5,711 +/- 1,276 ml/min, p < 0.002; total peripheral resistance (TPR) rose from 1,330 +/- 390 to 1,707 +/- 373 dynes x s/cm5, p < 0.007. After 24 months, LVMD decreased further from 224.6 +/- 43.1 to 195.7 +/- 46.3 g, p < 0.004. The relaxation time index (RTI) decreased from 64.7 +/- 20.4 to 52.4 +/- 18.0 ms, p < 0.045, suggesting improved diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of phenylephrine bolus administration on left ventricular function during postural hypotension in anesthetized patients

STUDY OBJECTIVE

To investigate the effect of intravenous (IV) phenylephrine (PHE) bolus administration on left ventricular function in patients who developed postural hypotension during isoflurane anesthesia in the head-up tilt (reverse Trendelenburg) position.

DESIGN

Prospective "before-after" trial.

SETTING

Operation theater of a university medical center.

PATIENTS

15 ASA physical status I and II patients without cardiovascular disorders.

INTERVENTIONS

The anesthetized patients were tilted from a supine horizontal to a 30-degree reverse-Trendelenburg position. Once a steady state was achieved, PHE 3 micrograms/kg was administered as an IV bolus dose.

MEASUREMENTS AND MAIN RESULTS

Transesophageal echocardiography was used to assess left ventricular function. We measured blood pressure (BP); heart rate; left ventricular end-systolic and end-diastolic area, diameter, and wall thickness; and ejection time at baseline and after tilt, immediately before and for a period of 3 minutes after PHE injection. We calculated fractional area change (FAC), mean velocity of circumferential fiber shortening (mVcf), and end-systolic wall stress. Head-up tilt caused a reduction of mean arterial pressure [from 68 to 54 mmHg (mean)], end-systolic and end-diastolic left ventricular area (from 9.7 to 6.5 cm2 and from 19.2 to 13.1 cm2, respectively) and end-systolic wall stress (from 56 to 33 10(3).dyne/cm2). FAC and mVcf remained unaltered. PHE administration restored baseline values or overcompensated the changes caused by tilt. FAC slightly decreased in response to PHE (from 0.51 to 0.43), end-systolic wall stress increased to 83 10(3).dyne/cm2, and mVcf remained unchanged.

CONCLUSION

PHE bolus administration effectively restored BP and cardiac filling, which were reduced after head-up tilt, without causing a relevant impairment of left ventricular function or an increase in end-systolic wall stress above the upper normal limit.

The role of peripheral capacitance and resistance vessels in hypotension following hemodialysis

The arterial pressure (AP) response to hemodialysis was studied with echocardiography and strain gauge plethysmography in 17 patients with end-stage renal disease; mean AP was unchanged in seven (group A) and was reduced by more than 10 mm Hg in 10 patients (group B). Following dialysis, body weight decreased and heart rate increased equally in both groups. Ejection fraction did not change in the two groups. Left ventricular end-diastolic volume fell by 13 +/- 10% in group A and by 24 +/- 16% in group B. Cardiac index (CI) fell in group B, but remained unchanged in group A. Systemic vascular resistance (SVR) did not change in both groups. The change in mean AP before and after dialysis was significantly correlated with that in Cl (r = 0.49, p less than 0.05), but not with that in SVR. Calf venous pressure-volume curves were not different between the two groups before dialysis. Hemodialysis shifted the curve toward the volume axis for group B but not for group A. These results suggest that hypotension following dialysis is mainly due to the fall in cardiac output, in which increases in venous distensibility play an important role.

Correlation of heart rate and radionuclide index of left ventricular contraction and relaxation

Since the cardiac function indices derived from radionuclide ventriculography (RNV) are considered to depend on the heart rate, we studied the relationship between systolic or diastolic indices and heart rates in patients with normal RNV and devised a method of correcting these indices according to the heart rate. For the systolic indices, the heart rate showed significant correlation with ET (r = -0.640), PER (r = 0.791) and TPE (r = -0.401) but not with EF, 1/3 EF, MNSER or 1/3 MNSER. For the diastolic indices, the heart rate correlated with FT (r = -0.938), RFT (r = -0.736), SFT (r = -0.803), 1/3 FF (r = -0.758), PFR (r = 0.759), 1/3 PFR (r = 0.742) and TPF (r = -0.389) but not with AFT, 1/3 MNDFR or AFF. These results indicate that many systolic and diastolic indices derived from RNV are affected by the heart rate. So when cardiac function is evaluated with the use of radionuclide indices, those which are independent of the heart rate should be used, or they should be corrected for the heart rate. As a method of correction, we proposed a rotating method obtained by manipulation of the regression equation of heart rates and indices. This new method is certain and easier to use when the correcting equations are set into a computer program.

Vascular changes in hemodialysis patients in response to recombinant human erythropoietin

The partial correction of anemia with recombinant human erythropoietin (rHuEpo) is frequently associated with an increase in arterial pressure and could oppose the beneficial effect of anemia correction on myocardial function. In order to analyze the influence of rHuEpo therapy on the vessels and the heart, we performed systemic and regional hemodynamics studies in 11 hemodialysis patients before and 10 to 35 weeks after initiation of rHuEpo therapy, when hemoglobin concentration was 6.8 +/- 0.9 and 10.6 +/- 0.66 g/dl (mean +/- SD), respectively. The mean arterial pressure remained unchanged during this period (88 +/- 21 vs. 88 +/- 15 mm Hg). Echocardiographic study showed that rHuEpo treatment led to a decrease in left ventricular end-diastolic diameter (4.9 +/- 0.5 vs. 5.1 +/- 0.6 cm; P less than 0.03), left atrial diameter (3.22 +/- 0.30 vs. 3.43 +/- 0.33; P less than 0.03), and left ventricular mass index (109.8 +/- 30.6 vs. 133 +/- 30.8 g/m2; P less than 0.05). Left ventricular ejection volume decreased from 86 +/- 24 to 75 +/- 19 ml (P less than 0.03) and heart rate from 76 +/- 9 to 70 +/- 10 beats/min (P less than 0.05). Cardiac index decreased from 4715 +/- 700 to 3635 +/- 444 ml/min/m2 (P less than 0.01) and peripheral resistances rose from 1480 +/- 162 to 1943 +/- 250 dynes.sec.cm-5.m2 (P less than 0.01). Fractional ejection and mean circumferential fiber shortening remained unchanged. The treatment with rHuEpo did not change the aortic diameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of acute alcohol ingestion on the left ventricular performance of normal subjects before and after incomplete autonomic blockade

The effects of acute alcohol ingestion on the left ventricular performance of nine normal subjects, mean age 25 years, were studied before and after incomplete autonomic blockade, produced by atropine, 0.04 mg/kg body weight, and propranolol, 0.2 mg/kg body weight. Left ventricular (LV) function curves (stroke volume vs. end-diastolic volume) were plotted from data generated before and after large variations in cardiac preload. Increase in preload was produced by five degrees of head-down tilt for 90 minutes; decrease in preload was produced by graduated lower body negative pressure to -40 mmHg. After incomplete autonomic blockade, the negative inotropic effects of acute alcohol ingestion were minimal but significant and manifest by the reduction in mean velocity of circumferential fiber shortening (p less than 0.05). Studies during wide variations in preload confirmed the importance of maintaining central blood volume after alcohol ingestion. Lower body negative pressure after both incomplete autonomic blockade and alcohol produced a further deterioration in mean velocity of circumferential fiber shortening (p less than 0.05).

Association between aluminum accumulation and cardiac hypertrophy in hemodialyzed patients

In order to investigate the possible role of aluminum accumulation on the myocardium, 50 stable asymptomatic hemodialysis patients were studied. Patient cardiac status was assessed by echocardiography. A deferroxamine (DFO) test, together with a bone biopsy, was performed to determine the magnitude of AI accumulation. Thus, an increase in serum AI after DFO (delta AI DFO) and stainable cortical bone aluminum (SCBA) were taken as parameters of AI load. Fourteen of 50 patients had no SCBA. They differed from the 36 patients with SCBA in that they had lower left ventricular mass (LVM) (P less than 0.001), increased velocity of circumferential fiber shortening (Vcf) (P less than 0.001), and higher mitral E-F slope (P less than 0.01). In the overall population there was a mild increment in serum AI and in delta AI DFO. The duration of dialysis treatment was correlated with SCBA and delta AI DFO (P less than 0.001). A correlation was observed between LVM and delta AI DFO (P less than 0.001) and between LVM and SCBA (P less than 0.001). Multivariate correlations analysis indicated that these relationships were independent of the duration of dialysis treatment. The present data suggest that, in hemodialysis patients aluminum accumulation may be associated with increased LVM.

Secondary hyperparathyroidism and cardiac hypertrophy in hemodialysis patients

Echocardiographic assessment of left ventricular function was performed in 66, stable hemodialysis patients and 50 normal controls matched for sex, age and arterial blood pressure. On the basis of bone histology, hemodialysis patients were classified into two groups: (1) patients with normal bone resorption; and (2) patients with active secondary hyperparathyroidism characterized by an increased bone resorption. Left ventricular function of these two subgroups were compared together as well as with the echocardiographic characteristics of normal controls. In comparison with normal controls, hemodialysis patients with normal bone resorption had an increased left ventricular volume (P less than 0.001) and left ventricular mass (P less than 0.001) with a similar left ventricular mass-to-volume ratio. Their systolic arterial pressure--mass-to-volume ratio correlation was similar to that of normal controls, indicating an adequate myocardial hypertrophy. Patients with increased bone resorption had high parathormone and alkaline phosphatase levels; though the left ventricular dilation was similar to that of hemodialysis patients with normal bone resorption, the left ventricular mass was lower (P less than 0.001) and was similar to the left ventricular mass of normal controls. In addition, patients with increased bone resorption had a lower mass-to-volume ratio (P less than 0.001) and their systolic arterial pressure--mass-to-volume ratio correlation exhibited a significant downward shift (P less than 0.001), suggesting an inadequate myocardial hypertrophy. Patients with increased bone resorption and secondary hyperparathyroidism had an increased heart rate, a higher systolic arterial pressure and end-systolic stress. Furthermore, they had an increased velocity of fiber shortening (P less than 0.01) and shorter left ventricular ejection time (P less than 0.001). In summary, present data suggest the possibility that parathormone may exert myocardial effects in hemodialysis patients.

Effects of acetate and bicarbonate dialysate on left ventricular performance

Whether bicarbonate dialysis (BiHD) improves left ventricular (LV) function more than acetate dialysis (AcHD) and whether AcHD exerts a negative inotropic effect remains controversial. To address this question, the LV contractile responses to both dialysate buffers were tested in six stable chronic dialysis patients not taking any cardiac or antihypertensive medicines. The patients were studied with echocardiography before and after an isovolemic dialysis (no weight change) with either buffer, and neither heart rate nor blood pressure were significantly altered during either procedure. The patients were studied at three different filling volumes so that LV function curves could be constructed. Both dialysates were associated with comparable and significant changes in LV end systolic volume (AcHD, 55 +/- 5 to 49 +/- 5 mL, P less than .001; BiHD, 56 +/- 5 to 49.5 +/- 5 mL, P less than .001), stroke volume (AcHD, 88 +/- 7 to 97 +/- 5 mL, P less than .01; BiHD, 89 +/- 7 to 97 +/- mL, P less than .05), and LV ejection fraction (AcHD, 60 +/- 7% to 65 +/- 8%, P less than .05; BiHD, 60 +/- 3 to 67 +/- 2%, P less than .001). In addition, the mean velocity of circumferential fiber shortening (VCF), an index of ventricular contractility, also increased significantly after dialysis with both dialysates (AcHD, .96 +/- .08 to 1.20 +/- .15, P less than .001; BiHD, .93 +/- .09 to 1.29 +/- .11, P less than .001). Finally, both dialysates were associated with upward shifts in the LV function curve of a similar magnitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Uremic cardiomyopathy: an inadequate left ventricular hypertrophy

Echocardiographic study of the left ventricle was performed in 57 selected, normotensive hemodialysis patients in comparison to 40 healthy controls matched for sex, age and blood pressure. The statistically significant abnormalities in uremic patients were an enlargement of the left ventricular end-diastolic diameter (LVEDiD) (5.58 +/- 0.60 vs. 5.05 +/- 0.5 cm; P less than 0.001) and an increase in the left ventricular radius to posterior wall-thickness ratio (r/Th) (3.65 +/- 0.68 vs. 3.27 +/- 0.44; P less than 0.001). Enlargement of the ventricle was related to anemia (P less than 0.001) and the hemodynamic effect of arteriovenous fistula. Ventricular radius to wall thickness ratio was inversely related to systolic arterial pressure in controls (P less than 0.001) and patients (P less than 0.01) with a significant upward shift of the regression in dialysis patients (P less than 0.001). In dialysis patients, the left ventricular posterior wall thickness (LVPWT) was inversely correlated to serum parathormone (PTH) level (P less than 0.001), and r/Th ratio was positively correlated to serum PTH (P less than 0.001). Bone biopsy was performed in 28 patients. Histomorphometric indexes of osteitis fibrosa were in dialysis patients, correlated to echocardiographic abnormalities; osteoclasts number was inversely correlated to LVPWT (P less than 0.001) and positively related to r/Th ratio (P less than 0.001). Osteoclastic resorption surfaces and LVPWT were inversely correlated (P less than 0.001), while a positive correlation between r/Th ratio and osteoclastic resorption surfaces was observed (P less than 0.001). Osteoblastic surfaces and tetracycline double-labeled surfaces were also correlated to LVPWT (P less than 0.001) and r/Th ratio (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Is selenium deficiency the cause of uraemic cardiomyopathy?

We studied the relationship between serum selenium (Se) and left ventricular performance in 33 patients on maintenance haemodialysis. Low serum Se was frequent. However, there were no significant differences in echocardiographic indices of left ventricular function between patients with serum Se less than 0.9 umol/l and those with serum Se greater than 0.9 umol/l. We conclude that Se deficiency is not an important cause of cardiac failure in uraemia.

Effects of acetate versus bicarbonate hemodialysis on left ventricular size and function

To investigate the effects of different types of hemodialysis on hemodynamics, left ventricular size and function, 10 patients with uremia due to chronic renal failure were examined using echocardiography and measurement of systolic time intervals before and after both acetate and bicarbonate hemodialysis. Both caused decreases in left ventricular end diastolic (acetate -3.2 vs. bicarbonate -5.1 mm, p less than 0.01 for both) and end systolic (-3.2 vs. -3.7 mm, p less than 0.01 for both) diameters, and increases in mVCF (+0.24 vs. +0.23 circ/s, p less than 0.005 for both) and fractional shortening (+2.7%, p less than 0.05 vs. +0.9%, NS). In systolic time intervals, the LVETI decreased (-28 vs. -38 ms, p less than 0.001 for both) and the PEP/LVET ratio increased (+0.04, NS vs. 0.09, p less than 0.01). There were no significant differences between the changes in any of the measured parameters caused by acetate or bicarbonate hemodialysis, except in blood bicarbonate concentration (+1.9 vs. +5.4 mmol/l, difference p less than 0.01). Thus hemodialysis with acetate or bicarbonate base causes similar decreases in left ventricular size apparently because of decreased diastolic filling, but in spite of this, there is an increase in left ventricular systolic function, apparently partially due to increased myocardial contractility.

Cardiac effects of short term arm crank training in paraplegics: echocardiographic evidence

The cardiac responses of male paraplegics to upper-body endurance training have been studied by M-mode echocardiography and CO2-rebreathing determination of cardiac output. Data for nine exercised subjects are compared with 5 controls. After 16 weeks of arm ergometer exercise, heart rates of trained individuals were 9 bt X min-1 lower during isometric handgrip effort (30% of MVC for 3 min), with a substantial decrease of rate pressure product (20%; p less than 0.05). In contrast (possibly because of greater anticipation) the control subjects developed a larger rate-pressure product with repetition of the standard isometric effort. Despite a significant increase of VO2 peak (19% and 31% after 8 and 16 weeks, respectively; p less than 0.05), echocardiographic LV mass, dimensions and indices of LV performance were unchanged by training, either at rest or during the isometric handgrip. Stroke volumes were significantly increased by 12-16% after training, both in isometric and in rhythmic work; at the highest intensity of arm ergometry, there was also a suggestion of increased cardiac output. We conclude that a short period of arm training is insufficient to induce cardiac hypertrophy, an increase of stroke volume with a decreased rate-pressure product but no change in echocardiographic indices of LV performance implies an improved myocardial efficiency. Possible explanations are a greater strength of the trained arms, and some increase of pre-loading (due to an increase of venous tone and more effective operation of the muscle pump after training).

Serial cardiac function tests in myocarditis

Sixteen patients (mean age 27 years, range 16 to 39 years) with the diagnosis of myopericarditis established by strict clinical criteria were evaluated following recovery 0.7 to 4.0 years (mean 2.7 years) later. Evidence of an acute viral infection was present in 44%. During the acute illness, the major clinical manifestations consisted of pericarditis in 10 patients, acute myocardial infarction in 5, right ventricular dysfunction in 5, bundle branch or hemiblock in 4, ventricular arrhythmias in 3, congestive heart failure in 3 and cardiogenic shock and inappropriate sinus tachycardia in one patient each. Holter monitoring, echophonocardiography and radionuclide ventriculography results were abnormal in 57, 67 and 64% of patients respectively. At follow-up, these tests were abnormal in 67, 7 and 73%. Focal wall motion abnormalities were present in five. Seventy-five percent of patients had one or more abnormal tests at last follow-up. Although 8 patients had improved by a scoring system, 5 patients had an increase in the number of abnormal tests, including one who died. These findings indicate that persistent abnormalities following recovery from myopericarditis are not rare and support the hypothesis that the syndrome of dilated cardiomyopathy may be a sequel of myopericarditis.

Comparative cardiac effects of hemodialysis and continuous ambulatory peritoneal dialysis

To assess the comparative cardiac effects of hemodialysis and continuous ambulatory peritoneal dialysis (CAPD), we performed M-mode echocardiography prior to and immediately following hemodialysis on 56 patients and during the dwell phase of CAPD on 39 patients. Hemodialysis produced a significant increase in the mean velocity of circumferential fiber shortening (VCF, an index of left ventricular systolic function) in patients with low VCF prior to dialysis, but resulted in no significant change in VCF in patients with normal predialysis VCF. Hemodialysis produced a significant increase in VCF in patients with a normal predialysis left ventricular end-diastolic volume index (LVEDVI), but resulted in no significant change in VCF in patients with left ventricular dilatation prior to dialysis. Hemodialysis produced a significant decrease in mean LVEDVI and mean stroke index, but resulted in no significant change in mean cardiac index due to a reflex increase in heart rate. Mean LVEDVI, mean stroke index, and VCF values in patients on CAPD were not significantly different from those observed immediately following hemodialysis. Mean cardiac index and mean heart rate were significantly lower in CAPD patients than in posthemodialysis patients. Pericardial effusion was observed in 25% of hemodialysis patients and 5% of CAPD patients (p less than 0.05). We conclude (1) the effects of hemodialysis on left ventricular performance are variable and depend in part on predialysis left ventricular volume and left ventricular systolic function, (2) except for a lower cardiac index, left ventricular hemodynamics for CAPD patients resemble those of posthemodialysis patients, and (3) pericardial effusion occurs with significantly higher frequency in patients on hemodialysis than in those on CAPD.

An echocardiographic study of patients with cardiovascular disease during dental treatment using local anesthesia

The cardiac function of nine patients who had various cardiovascular diseases was investigated by echocardiography during dental treatment in which local anesthetics were administered. The administration of lidocaine with epinephrine enhanced the cardiac output of all patients. Increased heart rate was responsible for the increased cardiac output in four cases, whereas increased stroke volume was responsible in the other five cases. The administration of prilocaine with felypressin caused less of an increase in cardiac function than did lidocaine, with only one patient showing a significant change in cardiac dynamics.

Evaluation of left ventricular function in children. Description of the method and normal values

Thirteen patients between 5 and 13 years were presented as a normal material for statical and dynamical echocardiographic measurements including left ventricular internal diameter in diastole and systole, shortening fraction, cardiac output, mean VCF, maximal normalized and not normalized rates of increase and decrease of diameter. The data were compact and normally distributed, and the rates of diameter change were independent of patients' age and BSA, and may therefore be used as general reference.

Left ventricular diastolic function in a population of healthy elderly subjects. An echocardiographic study

Diastolic left ventricular function was comparatively assessed in 19 healthy elderly individuals (mean age 71 years) and in 20 young normal subjects (mean age 26 years), using digitized echocardiograms. Peak and average filling rates were slower in the group of elderly subjects than in the younger population (128 +/- 26 and 75 +/- 11 v 182 +/- 37 and 92 +/- 17 mm per second, respectively, P less than .001). The duration of the rapid filling phase and the time to peak filling rate were significantly longer in the older than in the younger population (207 +/- 39 and 125 +/- 21 v 174 +/- 38 and 90 +/- 26 ms, respectively, P less than .01). The atrial contribution to total ventricular filling was 18 +/- 6% in the elderly and 10 +/- 3% in the young (P less than .001). The group differences of most of these measurements of diastolic function retained statistical significance after correction for heart rate. Measurements of left ventricular systolic function were similar in both age groups. The authors conclude that aging is associated with a decline of left ventricular compliance, unrelated to heart rate or systolic performance. The contribution of atrial contraction to ventricular filling is quantitatively larger in elderly individuals.

The effect of cardiac autonomic blockade on ventricular response to changes in preload

Echocardiographic (E) assessment of left ventricular response to increases (I) and decreases (D) in preload of 9 volunteer male subjects (mean age 25 +/- 2.0 years) was made during both control (C) and cardiac blocked (B) conditions. Cardiac autonomic blockade was produced by intravenous administration of atropine (0.04 mg/kg) and propranolol (0.2 mg/kg), while I was produced by 5 degrees head-down tilt (T) for 90 min and D by lower body negative pressure to -40 Torr. Increases in resting heart rate of 44% and diastolic blood pressure of 13% occurred after B, (P less than 0.05). During C, the alterations in preload produced mean changes in end-diastolic volume (EDV) ranging from 135 +/- 10 cm3 for I to 96 +/- 9.1 cm3 for D. Changes in stroke volume during condition C were significantly related to changes in EDV during preload alterations and conformed to a normal LV function curve and were described by SV = 0.6 EDV + 4.5 cm3 (r = 0.85; P less than 0.001). Similarly during B, SV = 0.43 EDV + 5.8 cm3 (r = 0.75; P less than 0.001). Comparison of the LV function curves produced during C and B showed that both slope of regression and r were significantly different (P less than 0.01). These data indicate that cardiac autonomic blockade produces a downward shift in the LV function curve indicating a depression in myocardial contractility. In addition, the data indicate that changes observed in LV function during wide variations in preload are independent of autonomic nervous system influences and are independent of the intrinsic heart rate.

Combining left ventricular systolic time intervals and M-mode echocardiography in the evaluation of primary pulmonary hypertension in women

Eight patients with primary pulmonary hypertension underwent systolic time intervals, M-mode echocardiography, and direct hemodynamic studies in order to determine the correlation between noninvasive parameters and hemodynamic variables and to evaluate the utility of these noninvasive studies in primary pulmonary hypertension. The ratio of the pre-ejection period to left ventricular ejection time (PEP/LVET) of the systolic time intervals was abnormally increased (greater than 0.42) for each subject; the increase in the PEP/LVET was secondary to a shortening of the left ventricular ejection time in four patients, prolongation of the pre-ejection period in one, or a combination of such, noted in three patients. In contrast, echocardiographic parameters of left ventricular function, specifically percent change in the minor axis of the left ventricle with systole, velocity of circumferential fiber shortening, and ejection fraction, were normal. In addition, a very good correlation was noted between PEP/LVET and total pulmonary resistance (r value = -0.89, p less than 0.05), while the echocardiographic parameters correlated well with stroke volume and cardiac output (r values ranged from 0.68 to 0.72, p less than 0.05). These results indicate that in primary pulmonary hypertension, the performance of both systolic time intervals and M-mode echocardiography noninvasively provides useful information concerning the hemodynamic status of these patients. Systolic time intervals provide an estimation of overall cardiac-cardiovascular performance, rather than left ventricular function alone, which in turn, is validly examined by M-mode echocardiography.

Echocardiographic assessment of cardiac function in infants and children

Echocardiography has become an established technique for the assessment of cardiac function in infants and children. M-mode echocardiography provides measurements of left ventricular diameter and wall thickness and allows calculation of their rate of change during the cardiac cycle. Left and right ventricular systolic time intervals may be determined from recordings of aortic and pulmonary valve motion. Two-dimensional echocardiographic images may be utilized for the determination of left and right ventricular volume and ejection fraction. Compared with other noninvasive imaging methods, echocardiography is a rapid, safe and inexpensive technique. Moreover, future developments are likely to include improved image processing and computer analysis of two-dimensional images.

Hemodynamic changes during acetate and bicarbonate hemodialysis

In a crossover, double-blind comparison, circulatory changes induced by hemodialysis with bicarbonate versus acetate dialysate were evaluated at the first exposure as well as after 2 weeks of acclimatization to each dialysate. Hemodialysis with bicarbonate dialysate resulted in only minor changes in blood pressure and left ventricular (LV) function as assessed by M-mode echocardiography. In contrast, the first exposure to acetate resulted in significant decreases in systolic (30 mm Hg) and diastolic (17 mm Hg) blood pressure as well as in LV end-diastolic and end-systolic dimensions (5-6 mm) and a rise in ejection fraction. After acclimatization, tolerance developed for the arterial vasodilatory effects of acetate, but not for the venous vasodilatory effect (persistent decrease in LV end-diastolic dimension). These results indicate that some of the circulatory changes induced by hemodialysis may be related more to the acetate infused than to fluid losses or relative autonomic insufficiency.

Left ventricular end-systolic wall stress-velocity of fiber shortening relation: a load-independent index of myocardial contractility

The velocity of circumferential fiber shortening (Vcf) is an index of myocardial performance which, although sensitive to contractile state, has limited usefulness because of its dependence on left ventricular loading conditions. This study investigated the degree and velocity of left ventricular fiber shortening as it relates to wall stress in an attempt to develop an index of contractility that is independent of preload and heart rate while incorporating afterload. Studies were performed in 78 normal subjects using M-mode echocardiography, phonocardiography and indirect carotid pulse tracings under baseline conditions. In addition, studies were performed on 25 subjects during afterload augmentation with methoxamine, 8 subjects before and during afterload challenge after increased preload with dextran and 7 subjects with enhanced left ventricular contractility with dobutamine. The relation of end-systolic stress to the velocity of fiber shortening and to the rate-corrected velocity of shortening (corrected by normalization to an RR interval of 1) was inversely linear with correlation coefficients of -0.72 and -0.84, respectively. Alterations in afterload, preload or a combination of the two did not significantly affect the end-systolic wall stress/rate-corrected velocity of shortening relation, whereas during inotropic stimulation, the values were higher, with 94% of the data points above the normal range. Age did not appear to affect the range of normal values for this index. In contrast, the end-systolic wall stress/fractional shortening relation was not independent of preload status, responding in a manner similar to that seen with a positive inotropic intervention. Thus, the velocity of circumferential fiber shortening normalized for heart rate is inversely related to end-systolic wall stress in a linear fashion. Accurate quantitation can be performed by noninvasive means and a range of normal values determined. This index is a sensitive measure of contractile state that is independent of preload, normalized for heart rate and incorporates afterload. In contrast, the end-systolic wall stress/fractional shortening relation is dependent on end-diastolic fiber length in the range of physiologically relevant changes in preload.

The effects of beta 1-adrenoceptor partial agonist ICI 118.587 on left ventricular function in patients with coronary heart disease

We investigated the effects of a new selective beta 1-adrenoceptor partial agonist, ICI 118.587, on left ventricular function in 14 patients with coronary heart disease and a history of stable angina pectoris. The drug (0.2 mg/kg) increased peak left ventricular dp/dt from 1518 to 1993 mm Hg/sec (P less than 0.001) and left ventricular Vmax from 1.63 to 2.08 circ/sec (P less than 0.001), while left ventricular end-diastolic pressure decreased (P less than 0.05). Measured by echocardiography, the fractional shortening of the left ventricular minor axis diameter and the mean velocity of the left ventricular circumferential fiber shortening increased (P less than 0.001) and the cardiac index increased by 36%, reflecting increased contractility mainly in the normal left ventricular wall areas. In coronary heart disease, ICI 118.587 increased left ventricular muscle contractility and output without untoward side effects in the majority of the patients.

Pulsus alternans. Its response to amyl nitrite inhalation

Marked pulsus alternans was observed in a patient with primary congestive cardiomyopathy. Afterload reduction with amyl nitrite caused the disappearance of the pulsus alternans. Investigation by phonocardiography, echocardiography, systolic time interval measurement and cardiac catheterization disclosed that during pulsus alternans the weak beat originated following a short diastolic filling period and generated much lower contractile force. This report may be relevant to the currently accepted concepts of afterload reduction in the treatment of chronic congestive heart failure.

Increased ionized calcium and left ventricular contractility during hemodialysis

Routine hemodialysis is associated with an increase in left ventricular contractility that is independent of a change in preload, but the mechanisms responsible are unknown. We investigated the importance of three distinct effects that regularly occur in hemodialysis and could potentially improve left ventricular contractility: the removal of uremic toxins, the increase in the plasma ionized calcium concentration, and the increase in the plasma bicarbonate concentration. Three different dialysates were used for each of eight stable patients on long-term hemodialysis, and left ventricular contractility was assessed by two-dimensional echocardiography before and after each dialysis. In the first procedure neither the ionized calcium nor the bicarbonate concentration was allowed to increase, and left ventricular contractility did not improve. In the second procedure, ionized calcium increased (from 4.4 to 5.4 mg per deciliter, P less than 0.001), bicarbonate concentration was held constant, and contractility increased (from 0.74 to 0.93 circumferences per second, P less than 0.005). In the third procedure, ionized calcium was kept constant, the bicarbonate concentration increased (from 19 to 24 mmol per liter, P less than 0.001), but contractility did not increase. These results suggest that the increase in ionized calcium that occurs in regular dialysis is a key factor in the improvement in left ventricular contractility observed during the procedure.

A noninvasive comparison of left ventricular performance in sickle cell anemia and chronic aortic regurgitation

Abnormalities of the cardiovascular system are common in patients with sickle cell anemia (SS). Noninvasive testing to document left ventricular dysfunction has yielded conflicting results. Left ventricular performance was evaluated in 27 patients with SS by M-mode and 2-D echocardiography, and systolic time intervals. Comparisons were made to 25 normal controls, and to 22 patients with chronic aortic regurgitation. Left ventricular diastolic diameter (LVDD) and cardiac index (CI) were significantly greater in the patients with SS than in controls (LVDD 5.3 +/- 0.4 vs. 4.7 +/- 0.5 cm; CI 4.2 +/- 1.3 vs. 3.1 +/- 0.8 liters/min/m2; both p less than 0.001). Left ventricular ejection fraction (EF) was slightly, but significantly less (62.9 +/- 7.3 vs. 67.0 +/- 5.4; p less than 0.05). In comparison to the patients with chronic aortic regurgitation, the LVDD in the patients with SS was slightly, but significantly lower (LVDD 5.3 +/- 0.4 vs. 5.9 +/- 0.6 cm; p less than 0.05). There was no significant difference between the patients in EF or CI (EF 62.9 +/- 7.3 vs. 63.3 +/- 4.4; CI 4.2 +/- 1.3 vs. 5.0 +/- 1.0 liters/min/m2; NS). Left ventricular EF was below 55 in three patients who also had hypertension at the time of examination. We conclude that patients with SS have resting left ventricular performance consistent with a high output state. Significant left ventricular dysfunction related to sickle cell disease alone was not demonstrated in this population, although the addition of hypertension appears to deleteriously affect resting left ventricular performance.

Effect of the Mueller manoeuvre at different lung volumes on left ventricular performance in normal subjects

The effect of reduced intrathoracic pressure at different lung volumes on cardiac function was assessed by echocardiographic measurements of left ventricular size in normal subjects who performed the Mueller manoeuvre at two preselected lung volumes. At functional residual capacity (FRC), both mean end-diastolic dimension and mean end-systolic dimension increased (5.1 +/- 0.4 to 5.4 +/- 0.5 cm; P less than 0.001 and 3.7 +/- 0.4 to 3.9 +/- 0.4 cm; P less than 0.025, respectively). At high lung volume (HLV), midway between FRC and total lung volume, mean end-diastolic dimension increased from 5.1 +/- 0.5 to 5.3 +/- 0.5 cm (P less than 0.001), less than than the increase at FRC, and mean end-systolic dimension increased from 3.5 +/- 0.4 to 3.9 +/- 0.4 cm (P less than 0.001), similar to the increase at FRC. Thus, mean stroke dimension and shortening fraction were reduced at HLV (1.5 +/- 0.2 to 1.3 +/- 0.2 cm and 30 +/- 4 to 26 +/- 2% respectively, P less than 0.025). At FRC and HLV respectively, mean left ventricular transmural pressure increased from 111 to 129 Torr (P less than 0.001) and from 111 to 128 Torr (P less than 0.001) in response to the Mueller manoeuvre, although intraesophageal (intrathoracic) pressure was significantly lower (P less than 0.001) during the Mueller manoeuvre at HLV. These results show that lung volume affects the left ventricular response to the Mueller manoeuvre. Furthermore, the changes in left ventricular dimensions induced by the Mueller manoeuvre are determined by the level of reduced intrathoracic pressure, through differing effects on left ventricular afterload and filling.

Estimation of circumferential fiber shortening velocity by echocardiography

The M-mode and two-dimensional echocardiograms of 40 young patients were analyzed to compare the mean circumferential fiber shortening velocity (Vcf) of the left ventricle calculated separately by two methods. The mean circumferential fiber shortening velocity was derived from the M-mode echocardiogram as minor axis shortening/ejection time and derived from the two-dimensional echocardiogram as actual circumference change/ejection time. With computer assistance, circumference was determined from the short-axis two-dimensional echocardiographic images during end-diastole and end-systole. Good correlations were obtained between the left ventricular diameter derived by M-mode echocardiography and the vertical axis during end-diastole (r = 0.79) and end-systole (r = 0.88) derived by two-dimensional echocardiography. Likewise, high correlations were noted between diameter and circumference in end-diastole (r = 0.89) and end-systole (r = 0.88). However, comparison of Vcf obtained by M-mode echocardiography with that obtained by two-dimensional echocardiography showed only fair correlation (r = 0.68). Moreover, the diameter/circumference ratio determined in end-diastole and end-systole differed significantly (p less than 0.001), possibly owing to the change in geometry of the ventricular sector image during systole. Although Vcf derived by M-mode echocardiography is a useful index of left ventricular performance, it does not truly reflect the circumference change during systole.