Cavity Wall Thickness Research Articles

Midwall mechanics in physiologic and hypertensive concentric hypertrophy

Objective We sought to analyze and compare midwall fractional shortening (mFS), and its relations with circumferential end-systolic stress (cESS) and relative wall thickness (RWT), among subjects with physiologic concentric left ventricular (LV) hypertrophy, patients with hypertension and concentric LV hypertrophy, and control subjects. Methods A total of 51 normotensive athletes and 56 young patients with hypertension and echocardiographic evidence of concentric LV hypertrophy were enrolled. In addition, 49 age- and sex-matched control subjects were recruited. LV cavity size and wall thicknesses, LV mass, RWT, cESS, and mFS were determined by echocardiography. Results The 3 groups were similar in age, sex, height, weight, body surface area, LV diameters, and conventional indices of systolic function. LV thicknesses, RWT, LV mass, and LV mass index were similarly increased in the athletes and in the hypertensive group when compared with the control subjects. A similar depression in mFS was observed in both the athletes (22.4 ± 2.6%) and hypertensive group (22.5 ± 3.6%) in comparison with the control group (24.5 ± 2.5%, P = .0003). The depression in mFS was still significant after taking into account the effect of cESS, but was no more evident after indexation of mFS by RWT or LV mass. At regression analysis, the relation between mFS and cESS showed a steeper negative slope in the patients with hypertension than in the other 2 groups. Conclusions MFS is similarly depressed in physiologic and hypertensive concentric LV hypertrophy. The depression is abolished by adjustment for RWT or LV mass, suggesting that geometric factors are the major determinants of midwall performance in both types of concentric LV hypertrophy. However, an impaired response to different values of cESS seems to exist only in hypertensive concentric LV hypertrophy, because increasing levels of cESS may be associated with more evident mFS depression in patients with hypertension than in the athletes and control subjects.

Morphological and functional differences in cardiac parameters between power and endurance athletes: a magnetic resonance imaging study.

The present study compared morphological and functional parameters of the left ventricle by magnetic resonance imaging (MRI) in competitive athletes engaged in endurance and power activities and sedentary control subjects. Twenty male subjects, 7 endurance-trained athletes (ETA) (age 23.8+/-3.5 yr), 7 strength-trained athletes (STA) (age 22.8+/-4.0 yr), and 6 sedentary controls (age 24.1+/-2.2 yr) were studied by MRI. In the ETA group body size related left ventricular mass (rel.LVM) was significantly higher than that in the STA group (71.0+/-9.2 vs 57.4+/-15.7 g/m3). The difference between their size related left ventricular wall thickness (rel.LVWT) values (9.37+/-1.0 vs 8.37+/-1.8 mm/m) was near to the level of significance (p=0.057). Relative left ventricular internal diameter (rel.LVID) was significantly higher in the ETA group compared to the STA group (42.3+/-1.0 vs 40.1+/-2.5 mm/m, p<0.05). The muscular quotient (MQ=LVWT/LVID) of the ETA group was not significantly higher compared to the strength athletes. Relative left ventricular end-diastolic volume (LVEDV) was also higher in the ETA group than in the STA group (69.5+/-6.7 vs 59.9+/-8.2 ml/m3, p<0.05) and the controls (53.6+/-3.7, p<0.001). Significantly higher relative stroke volume (SV) was measured in the ETA group compared to the STA group and the controls (41.0+/-5.7; 32.6+/-6.9; 32.0+/-3.2 ml/m3). According to the present data, the strongest impact on LV cavity size and wall thickness is caused by long-term high intensity endurance training. Intense strength training does not necessarily induce wall thickening.

Influence of cavity size and restoration methods on the cusp deflection in composite restoration

The aim of this study was to measure the cusp deflection during composite restoration for MOD cavity in premolar and to examine the influence of cavity dimension, C-factor and restoration method on the cusp deflection. Thirty extracted maxillary premolar were prepared to four different sizes of MOD cavity and divided into six groups. The width and depth of the cavity were as follows. Group 1; 1.5 × 1 ㎜, Group 2; 1.5 × 2 ㎜, Group 3; 3 × 1 ㎜, and Group 4-6; 3 × 2 ㎜ respectively. Group 1-4 were restored using bulk filling method with Z-250 composite. However, Group 5 was restored incrementally, and Group 6 was restored with an indirect resin inlay. The cusp deflection was recorded at the buccal and lingual cusp tips using LVDT probe for 10,000 seconds. The measured cusp deflections were compared between groups, and the relationship between the cube of the length of cavity wall/the cube of the thickness of cavity wall (L 3 / T 3 ), C-factor and cusp deflection or %flexure (100 × cuspal deflection / cavity width) was analyzed. The cusp deflection of Group 1-4 were 12.1 ㎛, 17.2 ㎛, 16.2 ㎛ and 26.4 ㎛ respectively. The C-factor was related to the %flexure rather than the cusp deflection. There was a strong positive correlationship between the L3 / T 3 and the cusp deflection. The cusp deflection of Group 5 and 6 were 17.4 ㎛ and 17.9 ㎛ respectively, which are much lower value than that of Group 4. [J Kor Acad Cons Dent 29(6):532-540, 2004]

Pipe cooling perspectives for superconducting accelerating cavities

We explore the rf characteristics of pipe cooled superconducting cavities versus bath cooled ones, using different pipe configurations and different liquid helium temperatures. Pipe cooled cavities can perform nearly as well as bath cooled ones, provided a suitable pipe configuration and cavity wall thickness is chosen. Pure thermal estimates and fits with experimental data show that pipe cooling is a viable solution for future cavities.

ECG-Gated 99mTc Single-Photon Emission CT for Assessment of Right Ventricular Structure and Function: Is the Information Provided Similar to Echocardiography?

(99m)Tc single-photon emission CT (SPECT) and ECG-gated SPECT can visualize well the right ventricle (RV) in most patients, but their utility for assessment of the RV has not been formally evaluated. We examined whether (99m)Tc SPECT/ECG-gated SPECT provide similar information to transthoracic two-dimensional Doppler echocardiography (2D-ECHO) regarding RV cavity size, wall thickness, and systolic function. Retrospective analysis. A major university teaching hospital. A consecutive series of 194 patients with good quality stress SPECT and 2D-ECHO studies performed within 1 day of each other and no significant interim cardiac events. RV size and function were visually assessed by SPECT/ECG-gated SPECT and 2D-ECHO. RV wall thickness was visually assessed by SPECT and measured in mm in end-diastole by 2D-ECHO. Of 142 patients with normal RV cavity size by SPECT, 134 patients (94%) had normal RV cavity size by 2D-ECHO. However, of 52 patients with RV dilation by SPECT, only 9 patients (17%) had RV dilation by 2D-ECHO. A perfusion abnormality in the right coronary artery territory was significantly associated with RV dilation by SPECT (p < 0.005) and 2D-ECHO (p < 0.05). Among 150 patients with ECG-gated SPECT, only 2 patients had abnormal RV systolic function, as compared with 18 patients by 2D-ECHO. RV wall thickness measurements by SPECT and 2D-ECHO did not correlate. For normal interpretations regarding RV cavity size, wall thickness, and systolic function, there is good agreement between (99m)Tc stress SPECT/ECG-gated SPECT and 2D-ECHO. However, there is poor overall agreement between gated SPECT/ECG-gated SPECT and 2D-ECHO regarding the presence of RV dilation, hypertrophy, and systolic dysfunction.

Assessment of regional systolic and diastolic wall motion velocities in highly trained athletes by pulsed wave Doppler tissue imaging

We studied the relationship between left ventricular (LV) function and the increased LV mass in 18 highly trained rowing athletes (14 men, 4 women; mean age 20.7 ± 4.5 years) using pulsed wave Doppler tissue imaging (PWDTI). Thirteen untrained volunteers, matched for age and body mass index, acted as control participants. Peak systolic, early diastolic (Ev), and late diastolic (Av) myocardial velocities (cm/s); Ev/Av ratio; and isovolumic relaxation time (ms) were measured at the level of basal lateral wall and basal posterior interventricular septum (bas-IVS) segments. In comparison with control participants, athletes showed a greater LV cavity size (P <.05), wall thickness (IVS, P <.001; posterior wall, P <.01), and mass index (P <.001). In athletes, systolic velocity of bas-IVS had increased (P <.001) and was positively correlated with IVS thickness (r = 0.66, P <.005) and LV mass index (r = 0.71, P <.001). Of the PWDTI-measured diastolic indexes, Ev/Av ratio significantly increased in athletes in comparison with control participants in both the examined segments (bas-IVS, P <.05; basal lateral wall, P <.05). When Ev and Av were separately considered, a different behavior was found in the 2 segments: Ev significantly increased in the basal lateral wall (P <.005); Av significantly decreased in the bas-IVS. The increase in the systolic velocity of bas-IVS suggests that septum greatly contributes to the longitudinal LV systolic shortening and increase of stroke volume in athletes compared with untrained participants. Moreover, the behavior of PWDTI diastolic velocities suggests a more effective relaxation activity in the longitudinal axis at the level of lateral wall. This study suggests therefore the usefulness of PWDTI in the assessment of functional properties of “athlete's heart” and differentiation from pathologic cardiac conditions. (J Am Soc Echocardiogr 2002;15:900-5.)

Resistance training and cardiac hypertrophy: unravelling the training effect.

Resistance training (RT) is a popular method of conditioning to enhance sport performance as well as an effective form of exercise to attenuate the age-mediated decline in muscle strength and mass. Although the benefits of RT on skeletal muscle morphology and function are well established, its effect on left ventricular (LV) morphology remains equivocal. Some investigations have found that RT is associated with an obligatory increase in LV wall thickness and mass with minimal alteration in LV internal cavity dimension, an effect called concentric hypertrophy. However, others report that short- (<5 years) to long-term (>18 years) RT does not alter LV morphology, arguing that concentric hypertrophy is not an obligatory adaptation secondary to this form of exertion. This disparity between studies on whether RT consistently results in cardiac hypertrophy could be caused by: (i) acute cardiopulmonary mechanisms that minimise the increase in transmural pressure (i.e. ventricular pressure minus intrathoracic pressure) and LV wall stress during exercise; (ii) the underlying use of anabolic steroids by the athletes; or (iii) the specific type of RT performed. We propose that when LV geometry is altered after RT, the pattern is usually concentric hypertrophy in Olympic weightlifters. However, the pattern of eccentric hypertrophy (increased LV mass secondary to an increase in diastolic internal cavity dimension and wall thickness) is not uncommon in bodybuilders. Of particular interest, nearly 40% of all RT athletes have normal LV geometry, and these athletes are typically powerlifters. RT athletes who use anabolic steroids have been shown to have significantly higher LV mass compared with drug-free sport-matched athletes. This brief review will sort out some of the factors that may affect the acute and chronic outcome of RT on LV morphology. In addition, a conceptual framework is offered to help explain why cardiac hypertrophy is not always found in RT athletes.

A systematic Monte Carlo study of secondary electron fluence perturbation in clinical proton beams (70-250 MeV) for cylindrical and spherical ion chambers.

Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron fluence perturbation factor, pe, was calculated using Monte Carlo transport of protons and secondary electrons. The influence of proton energy, cavity wall material (graphite, water, A150, PMMA, polystyrene), cavity radius, cavity wall thickness and positioning depth in water is studied. The influence of inelastic nuclear proton interactions is briefly discussed. It was found that pe depends on wall material; the largest values for pe were obtained for ion chambers with A150 walls (pe=1.009), the smallest values for graphite walls. The perturbation factor was found to be largely independent of proton energy. A slight decrease of pe with cavity radius was obtained, especially for low energy protons. The wall thickness was found to have no effect on pe in the range studied (0.025-0.1 cm). The depth of the cavity in a water phantom was also found to have an insignificant effect on pe. Based on the results in the paper for spherical and cylindrical ion chambers, a method to calculate pe for a thimble ion chamber is presented. The results presented in this paper for cylindrical and spherical ion chambers are in contradiction to the calculated electron fluence perturbation factors for planar ion chambers in the paper by Casnati et al.

M-mode errors in determination of left ventricular mass are greater with increasing cavity size and wall thickness: An MRI study Michael L. Chuang, Carol J. Salton, Kraig V. Kissinger, Daniel Levy, Christopher J. O'Donnell, Warren J. Manning. Beth Israel Deaconess Medical Center, Boston, MA, NHLBI's Framingham Heart Study, Framingham, MA

M-mode errors in determination of left ventricular mass are greater with increasing cavity size and wall thickness: An MRI study Michael L. Chuang, Carol J. Salton, Kraig V. Kissinger, Daniel Levy, Christopher J. O'Donnell, Warren J. Manning. Beth Israel Deaconess Medical Center, Boston, MA, NHLBI's Framingham Heart Study, Framingham, MA

Cardiac sympathetic dysfunction in an athlete's heart detected by 123I-metaiodobenzylguanidine scintigraphy.

The athlete's heart is commonly characterized by an increase in left ventricular mass because of an increase in the left ventricular diastolic cavity dimensions or wall thickness or both. Endurance exercise also induces numerous cardiovascular adaptations, including increased vagal tone. However, the sympathetic function has not yet been precisely elucidated, so the present study evaluated cardiac sympathetic nerve function from metaiodobenzylguanidine (MIBG) images obtained 15 and 180 min after the injection of 123I-MIBG at a dose of 111 MBq. The ratio of heart/mediastinum count (H/M) and the washout rates of 123I-MIBG (WR) were calculated in 25 consecutive patients who were athletes (aged 52+/-13 years) and 23 normal subjects. There was a significant difference in the H/M between the athletic and normal hearts (2.3+/-0.3 vs 2.6+/-0.3, p<0.01, Scheffe's test). An increased WR was observed in the athletes group when compared with the normal group (34+/-4 vs 28+/-3, p<0.01), and there was a significant correlation between WR and the left ventricular mass index (r=0.578, p<0.01). Prolonged exercise training may alter cardiac sympathetic nerve function, which can be detected by MIBG imaging.

Gender differences in athlete’s heart: association with 24-h blood pressure.: A study of pairs in sport dancing

Background: Long term athletic training is associated with an increase in left ventricular diastolic cavity dimensions, wall thickness, and mass. These changes are described as the “athlete’s heart”. In comparison to men, athletic training in women athletes is not a stimulus for substantial increase in left ventricular wall thickness. Although many variables are related to these gender differences in cardiac morphology, some factors such as 24-h blood pressure and the level of training have not been studied yet. Therefore pairs in sport dancing, in which the level of training of both partners is the same, were chosen as models in order to evaluate whether 24-h blood pressure contributes to sex-related differences in an athlete’s heart. Methods: Fifteen pairs in the national sport dancing team and 30 control subjects (15 males, 15 females) were studied. In all subjects casual and 24-h ambulatory blood pressures, echocardiography, and maximal stress testing were performed. Results: Female in comparison to male dancers had significantly lower M-mode ( P<0.004) and 2-D left ventricular mass index ( P<0.001), 24-h systolic blood pressure ( P<0.003), day systolic blood pressure ( P<0.002), casual systolic blood pressure ( P<0.025), and achieved significantly lower peak systolic blood pressure at stress testing ( P<0.004). Multiple stepwise regression analysis showed that the best predictors of 2-D left ventricular mass index are maximal work load and peak exercise systolic blood pressure, 24-h systolic blood pressure, day, and casual systolic blood pressure. Conclusions: Lower left ventricular mass index in female dancers can be partly explained by lower systolic blood pressures during 24-h and at exercise.

Norwood/Batista operation for a newborn with dilated myopathy of the left ventricle

Partial left ventriculectomy for dilated cardiomyopathy was first reported by Batista and associates1 in 1996. The rationale for this procedure is the increase in left ventricular cavity size in the absence of compensatory left ventricular wall thickness that is observed in dilated cardiomyopathy. This combination of factors results in an increase in wall stress per unit muscle mass, as predicted by the LaPlace equation. As wall stress increases, mechanical load eventually becomes nonsustainable and contributes to further dilation of the ventricle. Partial left ventriculectomy has been advocated as a method of restoring the balance between cavity size and wall thickness. Fundamental to this concept is the assumption that the left ventricular muscle is intrinsically normal or has recoverable contractile function. The variable results that have been reported in the adult literature may reflect patient selection according to the reversibility or recoverability of the underlying disease process. Despite the substantial worldwide experience with the Batista procedure in adult patients, there is limited experience with this procedure in children. The current case report describes the treatment of a patient in whom the diagnosis of dilated cardiomyopathy was made in utero. Clinical summary. A female infant was recognized in utero as having a dilated, poorly functioning left ventricle. Labor was induced at 36 weeks’ gestation, and she was delivered by normal, spontaneous, vaginal delivery. She underwent tracheal intubation in the delivery room because of poor tone and cyanosis. After her condition was stabilized, she was transferred to this institution. A postnatal echocardiogram again revealed massive dilation of the left ventricle with severely depressed systolic function. There was mild mitral valve hypoplasia with severe insufficiency. The aortic valve anulus measured 7 mm in diameter, and the valve appeared normal. The aortic arch was unobstructed, but there was retrograde flow via the ductus into the transverse aortic arch. The right ventricular systolic function appeared to be normal. A chest film revealed marked cardiac enlargement with compression of the left lung. From Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, Del. Received for publication Jan 18, 2000; accepted for publication Feb 18, 2000. Address for reprints: Richard D. Mainwaring, MD, Nemours Cardiac Center, Alfred I. duPont Hospital for Children, PO Box 269, Wilmington, DE 19899 (E-mail: rmainwar@nemours.org). J Thorac Cardiovasc Surg 2000;120:612-5 Copyright © 2000 by The American Association for Thoracic Surgery 0022-5223/2000 $12.00 + 0 12/54/106657 doi:10.1067/mtc.2000.106657 NORWOOD/BATISTA OPERATION FOR A NEWBORN WITH DILATED MYOPATHY OF THE LEFT VENTRICLE

Global left ventricular shape is not altered as a consequence of physiologic remodeling in highly trained athletes

It is uncertain whether left ventricular (LV) shape is altered as a consequence of intensive athletic conditioning. We assessed LV dimensions and shape by Fourier analysis from digitized LV endocardial borders in 22 elite rowers and 14 untrained controls. Athletes had greatly increased LV cavity dimension, wall thickness, volume, and mass; however, LV shape was normal in athletes, and associated with normal ejection fraction and diastolic filling pattern.

Effects of 16 weeks of resistance training on left ventricular morphology and systolic function in healthy men >60 years of age

Resistance training (RT) has gained popularity as an effective form of exercise for older adults. However, the effects of RT on left ventricular (LV) morphology and systolic function in older persons is not well known. The purpose of this study was to assess the effects of 16 weeks of RT on LV morphology and systolic function in healthy older men. Subjects were randomly assigned into a RT group (n = 10; mean ± SD age, 68 ± 3 years) or a nonexercise control group (n = 10; age 68 ± 4 years). RT was performed 3 times per week for 16 weeks at a mean intensity between 60% and 80% of 1 repetition maximum. Leg and bench press 1 repetition maximum and 2-dimensional echocardiography were performed at baseline and after 4, 8, 12, and 16 weeks of training in the RT group. Sixteen weeks of RT was associated with an increase in leg press maximal strength (baseline, 285 ± 48 kg; after 16 weeks, 367 ± 47 kg; p <0.05) and bench press maximal strength (baseline, 59 ± 11 kg; after 16 weeks, 69 ± 11 kg; p <0.05). No change in leg press maximal strength (baseline, 291 ± 59 kg; after 16 weeks, 290 ± 53 kg; p >0.05) or bench press maximal strength (baseline, 60 ± 9 kg; after 16 weeks, 61 ± 13 kg; p >0.05) was found in control subjects during the same time. RT was not associated with changes in LV cavity size, wall thickness, mass, or systolic function after 4, 8, 12, and 16 weeks of exercise. Thus, 16 weeks of RT was sufficient to increase leg press and bench press maximal strength but did not alter the size or systolic function of the senescent left ventricle.

Lateral cavity wall thickening as an early radiographic sign of mycetoma formation.

The sensitivity of chest radiography for the early detection of mycetoma formation within fibrotic cavities is poor. The purpose of this study was to determine the predictive value of the secondary sign of lateral cavity wall thickening for the detection of a radiographically occult mycetoma. The chest radiographs and CT scans of 70 patients who had a total of 109 fibrotic cavities on CT were reviewed by two observers. Dimensions of the cavity, mycetoma, and cavity wall thickness on chest radiography and CT scans were recorded. Mycetomas were visible in 41 of 99 cavities on chest radiographs and in 61 of 109 cavities on CT. Using CT as the gold standard for detecting the presence of mycetomas, the sensitivity of chest radiography for the presence of a mycetoma was 62 % and the specificity 94 %, and the positive and negative predictive values were 93 and 66 %, respectively. On logistic regression analysis, lateral wall thickness on chest radiography was predictive of the presence of a mycetoma (p < 0.0005) independent of other radiographic features. In patients with chronic fibrocavitary disease on chest radiography, the presence of lateral wall thickening is highly suggestive of an underlying mycetoma.

Left ventricular morphology and function in endurance-trained female athletes

In this study,we investigated resting left ventricular dimensions and function in trained female rowers, canoeists and cyclists. In male populations, such athletes have demonstrated the largest left ventricular wall thicknesses and cavity dimensions. Echocardiograms were analysed from 24 athletes (rowers and canoeists, n=12; cyclists, n=12) and 21 age-matched controls to measure left ventricular end-diastolic dimension and volume, and septal (ST) and posterior wall (PWT) thicknesses. Left ventricular mass was calculated from M-mode data. Systolic and diastolic function were calculated from M-mode and Doppler echocardiography, respectively. Height, body mass, body surface area and fat-free mass were determined anthropometrically. The athletes were well matched with the controls for all anthropometric variables except fat-free mass (rowers and canoeists 49.7 3.6 kg, cyclists 48.0 +\\- 3.8 kg, controls 45.0 +\\- 5.4 kg; P < 0.05). The left ventricular end-diastolic dimension, mass and volume, and septal and posterior wall thicknesses, were all significantly greater in the athletes than the controls (P < 0.05). These differences persisted (except for left ventricular end-diastolic dimension) even after allometric adjustment for group differences in fat-free mass. Stroke volume was larger (rowers and canoeists 102 +\\- 13 ml, cyclists 103 +\\0 16 ml, controls 80 +\\- 15 ml; P < 0.05) in both groups of athletes but all other functional data were similar between groups. As in male athletes, female rowers, canoeists and cyclists displayed significantly larger left ventricular cavity dimensions and wall thicknesses than controls.

Effect of Digoxin on Ventricular Remodeling and Responsiveness of beta-Adrenoceptors in Chronic Volume Overload.

BACKGROUND: Digoxin improves baroreflex function and reduces neurohumoral activation in severe heart failure, but it is uncertain how digoxin affects ventricular remodeling and progression to left ventricular dysfunction. In addition, the effect of digoxin in in vitro beta-adrenoceptor density and function, and contractile reserve in vivo is not well understood. METHODS AND RESULTS: To study this, we compared digoxin with placebo treatment in rats with chronic volume overload induced by aortocaval fistula and in sham-operated control animals. Left ventricular end-diastolic cavity dimensions (LVDd) and wall thickness were measured weekly by in vivo transthoracic echocardiography, and left ventricular mass (LVM) and percent fractional shortening (%FS) were calculated. Six weeks after fistula creation, simultaneous echocardiographic and invasive hemodynamic evaluation at rest and in response to incremental dobutamine (1-10 µg/kg/min intravenously) were measured. Myocardial plasma membrane beta-adrenoceptor density and maximal adenylate cyclase responses (V(max)) to isoproterenol, 5'-guanylylimi dodiphosphate, and forskolin were measured in vitro. Volume overload induced progressive increases in LVDd and LVM over the 6-week study period. Percent fractional shortening at rest, and the change in %FS in response to dobutamine stress were dramatically reduced 6 weeks after fistula creation. Although 6-week fistula animals had unchanged beta-adrenoceptor density (B(max)) and binding affinity (K(d)) as compared with controls, maximal adenylate cyclase responses to stimulation in vitro (V(max)) were markedly reduced. Digoxin treatment prevented this loss of responsiveness of adenylate cyclase but did not affect beta-adrenoceptor density or affinity in vitro. Digoxin had no effect on LVDd, LVM, %FS, or the response to dobutamine infusion in vivo. CONCLUSIONS: Although digoxin prevented beta-adrenoceptor desensitization and improved in vitro myocardial adenylate cyclase response, the cardiac response to adrenergic stimulation in vivo was not significantly improved. These results suggest that the role of beta-adrenoceptor desensitization in the progression from volume overload hypertrophy to left ventricular dysfunction and heart failure may be less important than previously thought. Furthermore, although digoxin treatment did produce modest hemodynamic benefits, it did not prevent progressive remodeling in this model.

Basic fibroblast growth factor induces myocardial hypertrophy following acute infarction in rats.

Basic fibroblast growth factor (bFGF) is a potent mitogen which induces growth of collateral vessels in ischaemic and infarcted myocardium. The effect of systemically administered bFGF on left ventricular (LV) function, myocardial hypertrophy and LV remodelling following acute myocardial infarction (MI) have not yet been fully investigated. Thirty Sprague-Dawley male rats were randomized to receive bFGF (0.5 mg) or rat albumin intraperitoneally for 1 week, beginning immediately after the induction of MI. Five animals served as controls and did not undergo any operation. Animals were killed 6 weeks after surgery and the hearts were perfused and fixed at physiological pressure. Transverse cross-sections from infarcted areas were stained with antibodies against proliferating cell nuclear antigen (PCNA) and Masson-trichrome and analysed with a coloured-image analyser for LV area (mm2), LV cavity diameter (mm), infarcted area (%), and wall thickness (mm) in infarcted and non-infarcted regions. LV area was similar in MI rats and in controls (41.7 +/- 6.9 and 43.0 +/- 1.5 mm2, respectively) and was significantly larger in MI bFGF-treated (MI/bFGF) animals (47.6 +/- 7.1 mm2) (P = 0.023). LV cavity diameter was significantly larger in the MI group than in MI/bFGF and control animals (6.0 +/- 0.8, 4.9 +/- 1.4, and 4.4 +/- 0.8 mm, respectively, P = 0.018). Wall thickness in the non-infarcted region was significantly smaller in MI animals (1.4 +/- 0.3 mm) than in MI/bFGF animals (1.6 +/- 0.4 mm) and the control group (1.6 +/- 0.1 mm) (P = 0.015). The ratio between LV cavity diameter/non-MI wall thickness was higher in MI than in control and MI/bFGF groups (4.8 +/- 1.6, 2.7 +/- 0.6 and 3.3 +/- 1.8, respectively, P = 0.03). Proliferating endothelial cells were significantly more abundant in infarcted than in normal areas in both MI and MI/bFGF groups, but with no significant differences between the groups. Intraperitoneal administration of bFGF did not cause any untoward extracardiac effects. Thus, systemic bFGF administration following acute MI in rats prevents dilatation of the LV, induces hypertrophy of the non-infarcted myocardium and exerts no untoward effects on extracardiac organs.

Athlete's Heart in Women

<h3>Objectives</h3> —To define the expression of "athlete's heart" in women by determining the alterations in cardiac dimensions associated with long-term intense conditioning in elite female athletes. <h3>Design</h3> —Prospective cardiovascular assessment conducted from 1986 through 1993. Subjects were evaluated using 2-dimensional, M-mode, and Doppler echocardiographic studies. <h3>Setting</h3> —Institute of Sports Science, Italian National Olympic Committee, Rome, Italy. <h3>Participants</h3> —A total of 600 elite female athletes (mean age, 21 years; range, 12-49 years) who had participated in vigorous training (mean duration, 9 years; range, 2-32 years) and had competed in 27 sports, including 211 athletes at the international level and 389 at the national level. A control group consisted of 65 sedentary volunteer women (mean age, 23.7 years; range, 14-41 years) who were free of cardiovascular disease and who did not participate in regular athletic training. <h3>Main Outcome Measures</h3> —Left ventricular end-diastolic cavity dimension and wall thickness. <h3>Results</h3> —Athletes demonstrated larger left ventricular end-diastolic cavity dimension (mean±SD)(49±4 mm) and greater maximal wall thickness (8.2±0.9 mm) than controls (46±3 mm and 7.2±0.6 mm;<i>P</i>&lt;.001). These dimensions were 6% and 14% larger in athletes. Among athletes, left ventricular cavity dimension was 40 mm to 66 mm, exceeded normal limits (&gt;54 mm) in 47 women (8%), and was within the range consistent with primary dilated cardiomyopathy (≥60 mm) in 4 athletes (1%). Training for endurance sports, such as cycling, cross-country skiing, and rowing had the greatest effect on cavity dimension. Left ventricular wall thickness was 6 mm to 12 mm in athletes and did not exceed normal limits or extend into the borderline gray zone with hypertrophic cardiomyopathy in any subject. Compared with data from 738 previously studied male athletes, female athletes showed significantly smaller left ventricular cavity dimension (11% less; P&lt;.001) and wall thickness (23% less;<i>P</i>&lt;.001). <h3>Conclusions</h3> —Highly trained women athletes frequently demonstrate cardiac dimensional changes as an adaptation to physical training, although absolute left ventricular cavity size exceeding normal limits was evident in a minority (8%) of women athletes and was rarely (1% of athletes) within the range of dilated cardiomyopathy. Athletic training was not a stimulus for substantial increases in absolute left ventricular wall thickness, which was within normal limits for all women athletes. These findings suggest that the clinical differentiation of athlete's heart and hypertrophic cardiomyopathy appears to be a diagnostic dilemma that is limited to male athletes.

A computer simulation of the effect of wall thickness on the metal flow in diecasting dies

A understanding of metal flow within the die cavity is of particular importance in the control of quality of pressure diecastings. A computational fluid dynamics technique named SMAC (Simplified Mark and Cell) was adapted and modified to analyze the metal flow pattern during the filling stage of a die cavity. The flow pattern and hence the pattern of air-entrapment are found to be sensitive to the cavity wall thickness. Flow-visualization experiments were carried out to verify the validity of the computer simulation for a rectangular-plate cavity with either a straight gate or a fan gate. There is a good agreement between the predicted flow and the results from water-analogue experiments.