Functional and metabolic evaluation of the athlete's heart by magnetic resonance imaging and dobutamine stress magnetic resonance spectroscopy

(31)P cardiac magnetic resonance spectroscopy during leg exercise at 3 Tesla

Investigation of phosphorus ((31)P) magnetic resonance spectroscopy under stress conditions provides a non-invasive tool to examine alterations in cardiac high-energy phosphate metabolism that may not be evident at rest. Our aim was to establish cardiac (31)P MR spectroscopy during leg exercise at 3T. The increased field strength should provide a higher signal to noise ratio than at lower field strengths. Furthermore, relatively high temporal resolution at a sufficiently fine spatial resolution should be feasible. (31)P MR spectra were obtained with a 3D acquisition weighted chemical shift imaging sequence in 20 healthy volunteers at rest, during dynamic physiological leg exercise and after recovery at 3T. Haemodynamic measurements were made throughout and the rate pressure product calculated. With exercise, the mean heart rate increased by 73%, achieving a mean increase in rate pressure product of 115%. The corrected PCr/ATP ratio for subjects at rest was 2.02 +/- 0.43, exercise 2.14 +/- 0.67 (P = 0.54 vs. rest) and at recovery 2.03 +/- 0.52 (P = 0.91 vs. rest, P = 0.62 vs. exercise). A cardiac (31)P MR spectroscopy physiological exercise-recovery protocol is feasible at 3T. There was no significant change in high-energy cardiac phosphate metabolite concentrations in healthy volunteers at rest, during physiological leg exercise or during recovery. When applied to patients with heart disease, this protocol should provide insights into physiological and pathological cardiac metabolism.

Physical activity and physiological cardiac remodelling in a community setting: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To evaluate the association of physical activity with left ventricular structure and function in the general population in a community setting.

DESIGN

Cross-sectional study.

SETTING

The Multi-Ethnic Study of Atherosclerosis (MESA), a population-based study of subclinical atherosclerosis.

PARTICIPANTS

A multiethnic sample of 4992 participants (aged 45-84 years; 52% female) free of clinically apparent cardiovascular disease.

INTERVENTIONS

Physical activity induces beneficial physiological cardiac remodelling in a cross-sectional study of non-athlete individuals.

MAIN OUTCOME MEASURES

Left ventricular mass, volumes and function were assessed by cardiac magnetic resonance imaging. Physical activity, defined as intentional exercise and total moderate and vigorous physical activity, was assessed by a standard semiquantitative questionnaire.

RESULTS

Left ventricular mass and end-diastolic volume were positively associated with physical activity (eg, 1.4 g/m(2) (women) and 3.1 g/m(2) (men) greater left ventricular mass in the highest category of intentional exercise compared with individuals reporting no intentional exercise; p = 0.05 and p<0.001, respectively). Relationships were non-linear, with stronger positive associations at lower levels of physical activity (test for non-linearity; p = 0.02 and p = 0.03, respectively). Cardiac output and ejection fraction were unchanged with increased physical activity levels. Resting heart rate was lower in women and men with higher physical activity levels (eg, -2.6 beats/minute lower resting heart rate in the highest category of intentional exercise compared with individuals reporting no intentional exercise; p<0.001).

CONCLUSIONS

In a community-based population free of clinically apparent cardiovascular disease, higher physical activity levels were associated with proportionally greater left ventricular mass and end-diastolic volume and lower resting heart rate.

Delayed improvement of right ventricular diastolic function and regression of right ventricular mass after percutaneous pulmonary valve implantation in patients with congenital heart disease

BACKGROUND

Percutaneous pulmonary valve implantation (PPVI) has been introduced as therapy for right ventricular (RV) to pulmonary artery conduit dysfunction in patients with congenital heart disease. It has been shown that RV systolic function improved early after PPVI. The effects of PPVI on RV diastolic function and RV hypertrophy have not yet been studied.

PURPOSE

The objective of this study is to assess early and late changes in systolic and diastolic RV function and RV mass after PPVI.

MATERIALS AND METHODS

Fourteen patients underwent PPVI (7 male, median age 15 years). Cardiac magnetic resonance imaging was performed before and at 2 time points after PPVI (at 1 and 16 months). Right ventricular volume and systolic and diastolic function as well as RV mass were assessed.

RESULTS

At 1 and 16 months after PPVI, the RV mass decreased from 28.6 +/- 2.1 to 25.6 +/- 2.2 g/m(2) (P = .03) and to 22.3 +/- 2.1 g/m(2) (P = .002). E/A volume ratio increased from 1.91 +/- 0.4 to 2.6 +/- 0.4 (not significant [NS]) and to 3.3 +/- 0.4 (P = .01). E/A peak flow ratio increased from 1.34 +/- 0.14 to 1.48 +/- 0.16 (NS) and to 1.73 +/- 0.14 (P = .04). E-wave deceleration time increased from 142 +/- 25 to 160 +/- 27 milliseconds (NS) and to 211 +/- 26 milliseconds (P = .007). At 1 month, RV end-diastolic volume decreased from 124 +/- 8 to 113 +/- 8 mL (P = .01) and RV ejection fraction increased from 36% +/- 2% to 46% +/- 2% (P = .001) without further improvement at 16 months.

CONCLUSION

After PPVI, in contrast to rapid improvement of RV systolic function, the improvement of RV diastolic function is delayed. The reduction of RV mass appears to be the underlying mechanism for improvement of RV diastolic function. Long follow-up for patients with PPVI is recommended.

Effect of intramyocardial bone marrow cell injection on diastolic function in patients with chronic myocardial ischemia

PURPOSE

To evaluate the effect of intramyocardial bone marrow cell injection on diastolic function in patients with chronic myocardial ischemia.

MATERIALS AND METHODS

In 24 patients (19 male; 65 +/- 9 years) with refractory angina (Canadian Cardiovascular Society [CCS] class III-IV) 84.6 +/- 28.7 x 10(6) bone marrow-derived mononuclear cells were injected intramyocardially (using the NOGA system) in regions with ischemia on Tc-99m tetrofosmin single photon emission computed tomography (SPECT). Diastolic function was evaluated at baseline and at three months using magnetic resonance imaging (MRI) and tissue Doppler imaging (TDI).

RESULTS

MRI revealed an increased early (E) peak filling rate (374 +/- 121 mL/second vs. 412 +/- 102 mL/second; P = 0.04), whereas the atrial (A) peak filling rate remained unchanged (340 +/- 81 mL/second vs. 334 +/- 93 mL/second; P = not significant [NS]). The E/A peak flow ratio increased from 1.09 +/- 0.33 to 1.23 +/- 0.47 at three months (P = 0.02). TDI demonstrated a significant improvement in early diastolic velocity (E') from 4.4 +/- 1.7 cm/second to 4.8 +/- 1.6 cm/second at three months (P = 0.03), whereas the late diastolic velocity (A') remained unchanged (6.0 +/- 1.6 cm/second vs. 6.0 +/- 1.7 cm/second; P = NS). Consequently, the E'/A' ratio increased from 0.74 +/- 0.19 to 0.84 +/- 0.28 at three months (P = 0.02).

CONCLUSION

Intramyocardial bone marrow cell injection in patients with chronic myocardial ischemia improved MRI and TDI-derived parameters of diastolic function.

Greater glycogen utilization during 1- than 2-adrenergic receptor stimulation in the isolated perfused rat heart

Differences in energy metabolism during beta(1)- and beta(2)-adrenergic receptor (AR) stimulation have been shown to translate to differences in the elicited functional responses. It has been suggested that differential access to glycogen during beta(1)- compared with beta(2)-AR stimulation may influence the peak functional response and modulation of the response during sustained adrenergic stimulation. Interleaved (13)C- and (31)P-NMR spectroscopy was used during beta(1)- and beta(2)-AR stimulation at matched peak workload (2.5 times baseline) in the isolated perfused rat heart to monitor glycogen levels, phosphorylation potential, and intracellular pH. Simultaneous measurements of left ventricular (LV) function [LV developed pressure (LVDP)], heart rate (HR), and rate-pressure product (RPP = LVDP x HR) were also performed. The heart was perfused under both substrate-free (SF) conditions and with exogenous glucose (G). The greater glycogenolysis was observed during beta(1)- than beta(2)-AR stimulation with G (54% vs. 38% reduction, P = 0.006) and SF (92% vs. 79% reduction, P = 0.04) perfusions. The greater beta(1)-AR-mediated glycogenolysis was correlated with greater ability to sustain the initial contractile response. However, with SF perfusion, the duration of this ability was limited: excessive early glycogen depletion caused an earlier decline in LVDP and phosphorylation potential during beta(1)- than beta(2)-AR stimulation. Therefore, endogenous glycogen stores are depleted earlier and to a greater extent, despite a slightly weaker overall inotropic response, during beta(1)- than beta(2)-AR stimulation. These findings are consistent with beta(1)-AR-specific PKA-dependent glycogen phosphorylase kinase signaling.

Effect of the sporting discipline on the right and left ventricular morphology and function of elite male track runners: a magnetic resonance imaging and phosphorus 31 spectroscopy study

BACKGROUND

Professional, long-term physical training is often associated with morphological and metabolic changes in the heart. This study was undertaken to assess the left ventricular (LV) and right ventricular (RV) morphology and function and the LV high-energy phosphates of athletes trained to a sustained power or aerobic exercise.

METHODS

Magnetic resonance imaging (MRI) of the LV and RV and phosphorous 31 magnetic resonance spectroscopy of the LV were performed by means of a 1.5-T clinical scanner in 23 elite track sprinters (sustained power or anaerobic power sprint training, 100-400 m) or marathon runners (sustained aerobic endurance training) and in 10 sedentary, young, lean men.

RESULTS

Athletes had LV hypertrophy and unaffected chamber size, systolic and diastolic functions, and high-energy phosphates metabolism. Also, the RV of the athletes was hypertrophied in comparison with that of the nonathletic controls, and the systolic and diastolic functions were unaffected; the chamber volume was higher in the sprinters (end-diastolic volume 190 +/- 15 mL) in comparison with that of the marathon runners (174 +/- 19 mL, P < .05) and controls (168 +/- 19 mL, P < .01) even if this difference, when adjusted for body surface area, was maintained only when compared with that of controls (P < .02).

CONCLUSIONS

Left ventricular and RV hypertrophy in athletes is associated with normal systolic and diastolic functions and resting cardiac energy metabolism, supporting its benign nature. A more pronounced RV dilatation was found in the anaerobic power athletes and further investigation is warranted to establish the clinical significance of this training effect.

QT peak prolongation is not associated with left ventricular hypertrophy in teenage professional football players

OBJECTIVE

QT peak prolongation is associated with left ventricular hypertrophy (LVH) in patients with hypertension. This study tests the hypothesis that QT peak prolongation correlates with LV mass index in apparently healthy young football players.

METHODS

QT peak and other ECG criteria for LVH were assessed in 117 male professional footballers (mean age 16.4 years +/- SD 0.76). Their left ventricular mass index (LVMI) was assessed by transthoracic echocardiography. Heart rate-corrected QT peak (QTpc) interval was measured in lead I using Bazett's formula. Spearman (2-tailed) test and UNIANOVA was used to assess if there were correlations between QT peak and the various echocardiographic and ECG indices of LVH.

RESULTS

Echocardiographic LVH, defined as LVMI > or = 134 g/m(2), was seen in 79 (70.5%) subjects. ECG-defined LVH was present in 54 (50 %) players by Sokolow-Lyon criteria, in 19 (16 %) players by Romhilt Score, in 5 (4 %) players by Cornell voltage criteria, and in 7 (6 %) players by Cornell product >2436 mm ms. There was no correlation between QT peak (QTpc) and LVMI on echocardiography (Spearman r = 0.058, 2-tailed P = 0.54). In addition, there was no relation between LVH and QTpc of lead I using any of the following ECG criteria: Sokolow-Lyon (P = 0.6), Romhilt (P = 0.3), Cornell voltage (P = 0.8), or Cornell product (P = 0.6).

CONCLUSION

QT peak interval, which is associated with pathological LVH in hypertensive patients and is a measure of risk of cardiac death, does not correlate with LVH characterized by myocyte hypertrophy in young apparently healthy professional footballers.

Exercise--is it possible to have too much of a good thing?

The graded benefit of exercise on cardiovascular risk is well established. Observational studies have, however, focused on mild to moderate levels of activity. In Australia, in excess of 30% of the adult population exercise in excess of the upper range as studied in the literature. There is limited evidence as to whether the risk/benefit ratio is maintained in those participating in regular intense exercise. Case reports and circumstantial evidence raise the possibility that more extreme exercise may have some detrimental effects. In effect, exercise may have a typical dose-response curve with a plateau or even toxicity at more extreme levels. Given the increasing popularity of endurance sporting pursuits, there is a need for further research into the cardiac adaptations and consequences of extreme habitual exercise.

Brain changes to hypocapnia using rapidly interleaved phosphorus-proton magnetic resonance spectroscopy at 4 T

Substantial controversy persists in the literature concerning the physiologic consequences hypocapnia, or low partial pressure of carbon dioxide (PaCO(2)). Invasive animal studies have demonstrated large pH increases (>0.25 U), phosphocreatine (PCr) decreases (>30%), and adenosine triphosphate (ATP) decreases (>10%) after hyperventilation (HV) (20 mm Hg PaCO(2)). However, using magnetic resonance spectroscopy, HV studies in awake humans have demonstrated only small pH changes ( approximately 0.05 U) and no changes in PCr or ATP. It remains important to ascertain whether this failure to detect PCr changes in human studies reflects a true absence of changes, or a limitation in data fidelity. The present study used a rapidly interleaved phosphorus-proton spectroscopy acquisition from large samples at high magnetic field (4 T), to measure pH, PCr, inorganic phosphate, beta-ATP, and lactate changes with high temporal and signal sensitivity. Five of six subjects had usable data. During 20 mins HV, PaCO(2) reached a minimum at 16 mins (17 mm Hg); however, the maximum pH change (+0.047) peaked earlier (14 mins). Maximal lactate increases were measured at 15 mins. By 10 mins, maximum changes were observed for PCr (-3.4%) and inorganic phosphate (+6.4%). No changes in beta-ATP were observed. The peak in pH, despite continued decreases in PaCO(2), suggests active buffering during HV. These data, and the small magnitude of early PCr and inorganic phosphate changes, do not support substantial energy compromise during HV. Other mitigating factors, such as anesthesia-induced deregulation of the cerebrovasculature, might have contributed to the exaggerated metabolic changes observed in previous animal investigations.

Right ventricular hypertrophy and diastolic dysfunction in arterial switch patients without pulmonary artery stenosis

OBJECTIVE

To assess pulmonary flow dynamics and right ventricular (RV) function in patients without significant anatomical narrowing of the pulmonary arteries late after the arterial switch operation (ASO) by using magnetic resonance imaging (MRI).

METHODS

17 patients (mean (SD), 16.5 (3.6) years after ASO) and 17 matched healthy subjects were included. MRI was used to assess flow across the pulmonary trunk, RV systolic and diastolic function, and RV mass.

RESULTS

Increased peak flow velocity (>1.5 m/s) was found across the pulmonary trunk in 14 of 17 patients. Increased RV mass was found in ASO patients: 14.9 (3.4) vs 10.0 (2.6) g/m2 in normal subjects (p<0.01). Delayed RV relaxation was found after ASO: mean tricuspid valve E/A peak flow velocity ratio = 1.60 (0.96) vs 1.92 (0.61) in normal subjects (p = 0.03), and E-deceleration gradients = -1.69 (0.73) vs -2.66 (0.96) (p<0.01). After ASO, RV mass correlated with pulmonary trunk peak flow velocity (r = 0.49, p<0.01) and tricuspid valve E-deceleration gradients (r = 0.35, p = 0.04). RV systolic function was well preserved in patients (ejection fraction = 53 (7)% vs 52 (8)% in normal subjects, p = 0.72).

CONCLUSIONS

Increased peak flow velocity in the pulmonary trunk was often observed late after ASO, even in the absence of significant pulmonary artery stenosis. Haemodynamic consequences were RV hypertrophy and RV relaxation abnormalities as early markers of disease, while systolic RV function was well preserved.

Cardiac and vascular adaptations to exercise

PURPOSE OF REVIEW

To briefly review some recent studies of cardiac and vascular adaptation to acute exercise and exercise training.

RECENT FINDINGS

Recent studies have suggested that prolonged strenuous bouts of exercise may be associated with transient impairment in systolic and diastolic function, referred to as 'cardiac fatigue'. Furthermore, some studies have reported increased circulating concentrations of cardiac troponins and brain natriuretic peptide following prolonged endurance exercise, suggestive of possible myocyte damage or impairment. Meanwhile, emerging studies of the effects of exercise training on diastolic function are somewhat conflicting; the discrepancies may relate to variability in study designs, indices selected to represent diastolic function or timing of measurements around training cycles. Finally, recent studies of vascular structure and function confirm established evidence for remodelling of large and small arteries and improvement in vascular function with exercise training.

SUMMARY

Emerging evidence suggests that prolonged strenuous exercise may be associated with 'cardiac fatigue' or 'cardiac damage', although the clinical implications remain obscure. Vascular adaptations to training improve vasomotor function and induce arterial enlargement, favouring decreased atherothrombotic risk.

Assessment of the effect of endurance training on left ventricular relaxation with magnetic resonance imaging

The purpose of the study was to assess the effect of endurance training on the early diastolic global and regional left ventricular (LV) relaxation with three magnetic resonance imaging (MRI) techniques. Fourteen subjects were examined with MRI before and after 3-month endurance training. Global early diastolic LV myocardial relaxation was assessed with mitral flow velocity mapping and regional LV early myocardial relaxation with myocardial tagging. LV end-diastolic and end-systolic volumes and mass were assessed with cine Magnetic resonance imaging (MRI). Mitral flow velocity mapping analysis revealed that the time to peak early filling shortened after training (before 112+/-32 ms, after 97+/-21, P<0.05), indicating more rapid global early myocardial relaxation. LV mass increased (97+/-19 g, 105+/-18, P<0.01) and end-systolic volume decreased (47+/-11 mL, 42+/-13, P<0.05). According to myocardial tagging analysis early myocardial relaxation in the septum and in the LV lateral wall increased (P<0.05). Regional tagging analysis showed enhanced myocardial relaxation in the basal septum (P<0.05). Global and regional LV early diastolic relaxation improved and physiological LV hypertrophy was found after the exercise training period for 3 months in healthy sedentary subjects.

The relative myocardial blood volume differentiates between hypertensive heart disease and athlete's heart in humans

AIMS

The adaptation of the myocardial microcirculation in humans to pathologic and physiologic stress has not been examined in vivo so far. We sought to test whether the relative blood volume (rBV) measured by myocardial contrast echocardiography (MCE) can differentiate between left ventricular (LV) hypertrophy (LVH) in hypertensive heart disease and athlete's heart.

METHODS AND RESULTS

Four groups were investigated: hypertensive patients with LVH (n = 15), semi-professional triathletes with LVH (n = 15), professional football players (n = 15), and sedentary control individuals without cardiovascular disease (n = 15). MCE was performed at rest and during adenosine-induced hyperaemia. The rBV (mL mL(-1)), its exchange frequency (beta, min(-1)), and myocardial blood flow (mL min(-1) g(-1)) were derived from steady state and refill sequences of ultrasound contrast agent. Hypertensive patients had lower rBV (0.093 +/- 0.013 mL mL(-1)) than triathletes (0.141 +/- 0.012 mL mL(-1), P < 0.001), football players (0.129 +/- 0.014 mL mL(-1), P < 0.001), and sedentary individuals (0.126 +/- 0.018 mL mL(-1), P < 0.001). Conversely, the exchange frequency (beta) was significantly higher in hypertensive patients (11.3 +/- 3.8 min(-1)) than in triathletes (7.4 +/- 1.8 min(-1)), football players (7.7 +/- 2.3 min(-1)), and sedentary individuals (9.0+/-2.5 min(-1)). An rBV below 0.114 mL mL(-1) distinguished hypertensive patients and triathletes with a sensitivity of 93% and a specificity of 100%.

CONCLUSION

Pathologic and physiologic LVH were differentiated non-invasively and accurately by rBV, a measure of vascularisation assessed by MCE.

Serum carboxyl-terminal propeptide of procollagen type I in exercise-induced left ventricular hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) induced by exercise is considered to be a physiologic adaptive mechanism without fibrogenic hyperactivity, as occurs in pathologic hypertrophy.

HYPOTHESIS

This study investigated serum markers of collagen synthesis and echo parameters of left ventricular diastolic function (LVdf) in 22 male athletes.

METHODS

Twenty-two highly competitive male athletes (10 cyclists, 12 soccer players) were studied with full history, clinical examination, Doppler echocardiogram, and serum concentration of the carboxyl-terminal propeptide of collagen type I (PIP). They were divided into two groups: normal left ventricular mass (N) with left ventricular mass index (LVMI) < 125 g/m2 (14 athletes) and LVH with LVMI > 125 g/m2 (8 athletes).

RESULTS

Age, body surface area, blood pressure, heart rate, and systolic function were not different between the groups. Serum concentration of PIP (N: 163 +/- 44.1 microg/l, LVH: 172.7 +/- 61.2 microg/l--NS) and LVdf (early to atrial peak mitral flow velocity ratio: [E/A] N: 1.77 +/- 0.47, LVH: 1.98 +/- 0.70--NS, and early to atrial peak mitral annulus velocity ratio: [Ea/Aa] N: 2.63 +/- 0.70, LVMI: 2.55 +/- 0.90 LV 1.61--NS) were similar in both groups.

CONCLUSIONS

Normal serum concentration of PIP in athletes with LVH in association with normal LVdf indicates the possibility that in this type of physiologic hypertrophy there is mainly an increase of myocyte size without interstitial fibrosis.

Association of fat-free mass and training status with left ventricular size and mass in endurance-trained athletes

OBJECTIVES

We sought to study the relationship between left ventricular (LV) size and body composition in male endurance athletes and age-matched control subjects.

BACKGROUND

Endurance training is associated with increases in both left ventricular mass (LVM) and left ventricular end-diastolic dimension (LVEDD) in athletes. In other populations, LVM is independently predicted by fat-free mass (FFM). We hypothesized that the increase in LV size and mass observed with training may be a normal response to increased FFM.

METHODS

Twelve young and 18 older male endurance athletes and 10 young and 18 older untrained men underwent exercise testing, echocardiography, and dual-photon x-ray absorptiometry body composition analysis. Univariate correlates (Spearman) and multivariate determinants of LVM and LVEDD were sought from: height, height(1.4), height(2.7), height(3.0), body surface area (BSA), FFM, weight, and body mass index. Un-indexed and indexed LVM and LVEDD were then compared.

RESULTS

Athletes were of a similar age, weight, and height, but had higher FFM and maximum oxygen uptake than untrained men. Both LVM and LVEDD were correlated with body size, including FFM, BSA, weight, and height (all p < 0.05). On multivariate analysis, FFM was the only independent predictor of both LVM (R(2) = 0.36, p < 0.001) and LVEDD (R(2) = 0.35, p < 0.001). Furthermore, LVM and LVEDD (un-indexed and indexed to BSA and height) were different between athletes and non-athletes, but not when indexed to height(2.7) or FFM.

CONCLUSIONS

Both LVM and LVEDD are predicted by FFM in endurance athletes, and when indexed to FFM, no training-related differences were observed. Thus, the extent of LV remodeling (athletic heart) in trained individuals may reflect a normal physiologic response to increased FFM induced by training.

Serial left ventricular adaptations in world-class professional cyclists

OBJECTIVES

The purpose of this research was to study long-term left ventricular (LV) adaptations in very-high-level endurance athletes.

BACKGROUND

Knowledge of cardiac changes in athletes, who are at particularly high risk of sudden cardiac death, is mandatory to detect hypertrophic cardiomyopathy (HCM) or dilated (DCM) cardiomyopathy.

METHODS

We carried out echocardiographic examinations on 286 cyclists (group A) and 52 matched sedentary volunteers (group C); 148 cyclists participated in the 1995 "Tour de France" race (group A1), 138 in the 1998 race (group A2), and 37 in both (group B).

RESULTS

In groups A, A1, A2, and C, respectively, diastolic left ventricular diameter (LVID) was 60.1 +/- 3.9 mm, 59.2 +/- 3.8 mm, 61.0 +/- 3.9 mm, and 49.0 +/- 4.3 mm (A vs. C and A1 vs. A2, p < 0.0001), and maximal wall thickness (WT) was 11.1 +/- 1.3 mm, 11.6 +/- 1.3 mm, 10.6 +/- 1.1 mm, and 8.6 +/- 1.0 mm (A vs. C and A1 vs. A2, p < 0.0001). Among group A, 147 (51.4%) had LVID >60 mm; 17 of them had also a below normal (<52%) left ventricular ejection fraction (LVEF). Wall thickness exceeded 13 mm in 25 athletes (8.7%) (always <15 mm), 23 with LVID >55 mm. In group B, LVID increased (58.3 +/- 4.8 mm to 60.3 +/- 4.2 mm, p < 0.001) and WT decreased (11.8 +/- 1.2 mm to 10.8 +/- 1.2 mm, p < 0.001) with time.

CONCLUSIONS

Over one-half of these athletes exhibited unusual LV dilation, along with a reduced LVEF in 11.6% (17 of 147), compatible with the diagnosis of DCM. Increased WT was less common (always <15 mm) and scarce without LV dilation (<1%), eliminating the diagnosis of HCM. Serial examinations showed evidence of further LV dilation along with wall thinning. These results might have important implications for screening in athletes.

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.

MR flow mapping of dobutamine-induced changes in diastolic heart function

PURPOSE

To evaluate the ability of MR flow mapping to measure changes in left ventricular filling during beta-adrenergic stimulation.

MATERIALS AND METHODS

Mitral flow was measured in 10 healthy volunteers using conventional free breathing fast-field echo (FFE) with a spatial resolution of 2.7 x 2.2 mm and a temporal resolution of 22 msec. The sequence was repeated during dobutamine infusion (20 microg/kg/minute).

RESULTS

Stroke volume increased from a median of 99 mL (range: 68-142 mL) (Note: values as presented are medians and ranges, throughout) to 114 mL (87-180 mL) (P < 0.05). Both early (E) peak filling rate (554 mL/second [433-497 mL] to 651 mL/second [496-1096 mL/second]) (P < 0.05) and atrial (A) peak filling rate (238 mL/second [183-352 mL/second] to 341 mL/second [230-538 mL/second]) (P < 0.05) increased. These changes, together with the increase in E acceleration peak and A deceleration peak, were consistent with facilitated myocardial relaxation.

CONCLUSION

Conventional free breathing FFE has the ability to measure the effects of beta-adrenergic stimulation on left ventricular filling.

Imaging of cardiopulmonary diseases

Clear physiologic adaptations to endurance and resistance training occur in the myocardium. These morphologic changes have been identified primarily by echocardiography. In the evaluation of the symptomatic athlete, imaging is a valuable tool. To differentiate athletic hypertrophy from hypertrophic cardiomyopathy, echocardiography, or MRI may be used, although the latter may be superior in the accurate assessment of wall thickness. Either imaging modality may be used to differentiate athletic dilatation from dilated cardiomyopathy in which systolic dysfunction always accompanies the dilatation. To exclude anomalous coronary arteries, either MRI or CT is a reasonable examination, although the latter requires x-ray exposure and iodinated contrast dye. Chest radiograph continues to be the standard imaging modality for athletic lung disease, whereas fluoroscopy and laryngoscopy are useful for identifying vocal cord dysfunction. Knowledge of the utility of these different imaging modalities is crucial to the practitioner of sports medicine.

Left ventricular remodeling early after aortic valve replacement: differential effects on diastolic function in aortic valve stenosis and aortic regurgitation

OBJECTIVES

The aim of this study was to evaluate the effect of aortic valve replacement (AVR) on left ventricular (LV) function and LV remodeling, comparing patients with aortic valve stenosis to patients with aortic regurgitation.

BACKGROUND

Aortic valve disease is associated with eccentric or concentric LV hypertrophy and changes in LV function. The relationship between LV geometry and LV function and the effect of LV remodeling after AVR on diastolic filling, in patients with aortic valve stenosis compared with aortic regurgitation, are largely unknown.Nineteen patients with aortic valve disease (12 aortic valve stenosis, 7 aortic regurgitation) were studied using magnetic resonance imaging to assess LV geometry and LV function before and 9 +/- 3 months after AVR. Ten age-matched healthy males served as control subjects.

RESULTS

Before AVR, the ratio between left ventricular mass index (LVMI) and left ventricular end-diastolic volume index (LVEDVI) was only increased in patients with aortic valve stenosis (1.37 +/- 0.16 g/ml) compared with control subjects (0.93 +/- 0.08 g/ml, p < 0.05). After AVR, LVMI/LVEDVI decreased significantly in aortic valve stenosis (to 1.15 +/- 0.14 g/ml, p < 0.0001), but increased significantly in aortic regurgitation (1.02 +/- 0.20 g/ml to 1.44 +/- 0.27 g/ml, p < 0.0001). Before AVR, diastolic filling was impaired in both aortic valve stenosis and aortic regurgitation. Early after AVR, diastolic filling improved in patients with aortic valve stenosis, whereas patients with aortic regurgitation showed a deterioration in diastolic filling.

CONCLUSIONS

Early after AVR, patients with aortic valve stenosis show a decrease in both LVMI and LVMI/LVEDVI and an improvement in diastolic filling, whereas in patients with aortic regurgitation, LVMI decreases less rapidly than LVEDVI, causing concentric remodeling of the LV, most likely explaining the observed deterioration of diastolic filling in these patients.

Athlete's heart: right and left ventricular mass and function in male endurance athletes and untrained individuals determined by magnetic resonance imaging

OBJECTIVES

Athlete's heart represents a structural and functional adaptation to regular endurance exercise.

BACKGROUND

While left ventricular (LV) hypertrophy of the athlete's heart has been examined in many studies, the extent of right ventricular (RV) hypertrophy is still uncertain because of its complex shape and trabecular structure. To examine RV hypertrophy, we used magnetic resonance imaging (MRI) and hypothesized that athlete's heart is characterized by similar LV and RV hypertrophy.

METHODS

The LV and RV mass, volume, and function in 21 male endurance athletes (A) (27 +/- 4 years; 70 +/- 8 kg; 178 +/- 7 cm; maximal oxygen uptake [VO(2)max]: 68 +/- 5 ml/min per kg) and 21 pair-matched untrained control subjects (C) (26 +/- 3 years; 71 +/- 9 kg; 178 +/- 6 cm; VO(2)max: 42 +/- 6 ml/min per kg) were analyzed by MRI (Magnetom Vision 1.5T, Siemens, Erlangen, Germany).

RESULTS

Left ventricular masses: (A: 200 +/- 20 g; C: 148 +/- 17 g) and RV masses (A: 77 +/- 10 g; C: 56 +/- 8 g) differed significantly between the groups (p < 0.001). The LV and RV end-diastolic volumes (EDV) (LV-EDV 167 +/- 28 ml [A]; 125 +/- 16 ml [C]; RV-EDV 160 +/- 26 ml [A]; 128 +/- 10 ml [C]), and stroke volumes (SV) (LV-SV: 99 +/- 18 ml [A], 74 +/- 11 ml [C]; RV-SV: 102 +/- 18 ml [A], 79 +/- 8 ml [C]) were significantly different between the athletes and control subjects (p < 0.001), whereas ejection fractions (EF) (LV-EF: 59 +/- 3% [A]; 59 +/- 6% [C]; RV-EF: 63 +/- 3% [A], 62 +/- 3% [C]) and LV-to-RV ratios were similar for both groups (LV-to-RV mass: 2.6 +/- 0.2 [A], 2.6 +/- 0.3 [C]; LV-to-RV EDV: 1.05 +/- 0.14 [A], 0.99 +/- 0.14 [C]; LV-to-RV SV: 0.98 +/- 0.17 [A], 0.95 +/- 0.17 [C]; LV-to-RV EF: 0.93 +/- 0.07 [A], 0.96 +/- 0.10 [C]).

CONCLUSIONS

Regular and extensive endurance training results in similar changes in LV and RV mass, volume, and function in endurance athletes. This leads to the conclusion that the athlete's heart is a balanced enlarged heart.

Diastolic dysfunction in hypertension

Heart failure is one of the most common causes of cardiovascular morbidity and mortality, and hypertension is the most common cause of cardiac failure. Recent studies have shown that isolated diastolic dysfunction very often accompanies hypertensive heart disease. Ventricular diastolic function may be divided into an active relaxation phase and a passive compliance period. These two components have been investigated invasively, and they remain the gold standards for the study of diastolic function. However, in the routine clinical setting, echocardiographic and Doppler techniques are most useful for evaluating ventricular filling. Thus, analysis of E and A waves of mitral flow have provided important and useful information. Unfortunately, these indices depend on too many factors. Newer indices obtained from ventricular time intervals, tissue Doppler imaging, and color M-mode echocardiography have enhanced the means to assess diastolic function. In addition, new methods including MRI and cine CT have also provided better understanding of left ventricular filling in hypertension. Using these techniques, diastolic dysfunction has been found to be common in patients with hypertension, even before left ventricular hypertrophy is demonstrable and before hypertension in young, normotensive male offspring of hypertensive parents has developed. Furthermore, it has been made clear recently that myocardial ischemia and fibrosis are two important factors associated with diastolic dysfunction in hypertension.

MR Imaging of the heart with cine true fast imaging with steady-state precession: influence of spatial and temporal resolutions on left ventricular functional parameters

The influence of changes in spatial and temporal resolutions on functional parameters in the left ventricle (LV) were investigated with magnetic resonance (MR) imaging with a modified true fast imaging with steady-state precession, or FISP, two-dimensional sequence that provided temporal resolution of 21-90 msec and spatial resolution of 1-3 mm. MR imaging in the heart was performed in 15 healthy volunteers. A decrease in LV functional parameters was observed with reduced spatial and temporal resolutions. The influence of temporal resolution was more relevant.

Physiologic and pathologic myocardial hypertrophy--physiologic and pathologic regression of hypertrophy?

Hypertrophy of the left ventricle is an adaptive phenomenon of ambiguous biological value. It enables improvement of the heart performance without substantial enhancement of energetic demands. On the other hand, pathologic left ventricular hypertrophy (LVH) is characterized by increased fibrosis, diminished coronary flow reserve and protein remodeling, resulting in increased cardiovascular morbidity and mortality. Achievement of LVH regression is thus considered a principal therapeutic aim. However, the reversal of LVH is a very complex process in which both hemodynamic and non-hemodynamic alterations participate. Reversal of LVH does not mean the re-expression of the original genotype and normalization of myocardial structure and function. It does not guarantee that the heart will be normal in all aspects. Regression of hypertrophy induced by different therapeutic means may exhibit different properties and patterns, with variable biological implications. Physiologic growth stimulators seem to induce LVH without prognostically undesirable alterations. It is a challenge to determine which approach to treatment of hemodynamic overload and concomitant LVH is optimal.

Organs/systems potentially involved in one model of programmed hypertension in sheep

1. When pregnant ewes and their fetuses are exposed to the synthetic glucocorticoid dexamethasone for 2 days early in pregnancy (days 26-28; term 145-150 days), female offspring have increased blood pressure relative to a control group. In one series, this was shown to be due to increased cardiac output, concomitant with a reset mean arterial pressure/heart rate reflex. The first group of such animals had, by the age of 7 years, left ventricular hypertrophy and reduced cardiac functional capacity. 2. The elevation in blood pressure is not maintained by any change in the peripheral renin-angiotensin system (RAS). 3. There is, however, preliminary evidence that some aspects of local RAS (particularly in the kidney and brain) could have participated in the 'programming' event. The levels of mRNA for angiotensin II receptors (AT1, AT2) and angiotensinogen are increased in the kidney of such dexamethasone-treated fetuses in late gestation (130 days), some 100 days after steroid treatment. Similar increases in AT1 mRNA in the medulla oblongata of the fetal brain and large increases of mRNA for angiotensinogen occur in the hypothalamus. 4. These findings, together with evidence from the literature, suggest that both the kidney and parts of the brain are affected by events that also 'program' high blood pressure in the offspring of animals in which the intra-uterine environment has been perturbed at some stage.

Aortic valve replacement in patients with aortic valve stenosis improves myocardial metabolism and diastolic function

PURPOSE

To evaluate whether functional and metabolic changes recover after aortic valve replacement (AVR).

MATERIALS AND METHODS

Eighteen men with aortic valve stenosis (mean pressure gradient +/- SD, 79.9 mm Hg +/- 15.1) underwent magnetic resonance (MR) imaging and phosphorus 31 MR spectroscopy. In nine patients who underwent AVR, MR imaging and spectroscopy were repeated 40 weeks +/- 12 after AVR. Ten age-matched healthy men were control subjects.

RESULTS

Before AVR, the myocardial phosphocreatine (PCr)-to-adenosine triphosphate (ATP) ratio in the 18 patients was 1.24 +/- 0.17 and 1.43 +/- 0.14 in the control group (P <.01). In nine patients who underwent follow-up MR spectroscopy, the ratio increased from 1.28 +/- 0.17 to 1.47 +/- 0.14 (P <.05) following AVR. Before AVR, early acceleration peak corrected for cardiac output was (0.043 +/- 0.008) x 10(-3) sec(-1) in patients and (0.081 +/- 0.033) x 10(-3) sec(-1) in the control group (P <.05). After 40 weeks +/- 12, the mean early acceleration peak corrected for cardiac output in the nine patients increased significantly to (0.055 +/- 0.006) x 10(-3) sec(-1) (P <.05), although it was still significantly lower than that of the control group (P <.05). Before AVR, a significant correlation was found between the myocardial PCr-ATP ratio and left ventricular diastolic function (n = 18; P <.05).

CONCLUSION

Severe aortic valve stenosis leads to a decreased myocardial PCr-ATP ratio and impairment of left ventricular diastolic function; following AVR, the ratio normalizes completely, whereas function improves significantly. There is an association between altered myocardial high-energy phosphate metabolism and impaired left ventricular diastolic function.

Time course of structural adaptations in chronic AV block dogs: evidence for differential ventricular remodeling

To determine the nature and time course of biventricular hypertrophy and concomitant electrical and mechanical changes after creation of complete atrioventricular block (CAVB), six adult dogs (22–30 kg) were subjected to serial magnetic resonance imaging (MRI) and electrocardiography. After 6 days of CAVB, left ventricular (LV) mass, ejection fraction (EF), and Q-T time at a paced rhythm of 60 beats/min were already significantly increased. Maximal values were reached within 14–21 days of CAVB: LV mass, from 116 ± 11 to 143 ± 12 g; right ventricular (RV) mass, from 40 ± 3 to 55 ± 6 g; EF, from 68 ± 6% to 86 ± 5%; and Q-T time, from 285 ± 25 to 330 ± 35 ms, all P < 0.05. Cardiac output returned to baseline at day 14. End-diastolic wall thickness increased only in the RV, in which angiotensin type 1 (AT1) receptor mRNA expression was significantly greater. The autopsy correlated well with the MRI results ( r = 0.98, P≤ 0.01). In conclusion, electrophysiological, mechanical, and structural adaptation processes after bradycardia-induced volume overload develop rapidly and are completed within 3 wk. The degree of hypertrophy was greater in the RV, which was associated with an increase in AT1receptor mRNA.

Advances in human cardiac 31P-MR spectroscopy: SLOOP and clinical applications

Phosphorus magnetic resonance spectroscopy (31P-MRS) has revealed a lot about the biochemistry of physiological and pathological processes in the heart. Nevertheless, until today, cardiac 31P-MRS has not had any clinical impact, albeit some pioneering studies demonstrated that 31P-MRS can indeed provide diagnostic information. In this paper, the development of techniques for human cardiac 31P-MRS over the past decade is reviewed, and the requirements for a reliable clinical measurement protocol are discussed. Spatial localization with optimal pointspread function (SLOOP) is a new method to achieve spatial localization and absolute quantitation. Its properties are detailed, and preliminary findings in patients with dilated cardiomyopathy or myocardial infarction are presented.

Detection of changes in diastolic function by pulmonary venous flow analysis in women athletes

BACKGROUND

Left ventricular cavity dimension, wall thickness, relaxation, and filling increase with exercise training and have a role in enhancing physical performance. We probed whether changes in diastole may develop separately from those in cardiac morphometry and still contribute to improve physical performance. Challenging diastole by preload reduction with standing and integrating mitral flow analysis with the pulmonary venous flow analysis were viewed as a means for detecting fine diastolic variations.

METHODS

Patterns of mitral, tricuspid, and pulmonary venous flow were evaluated by echo Doppler imaging in the supine and standing positions in 11 long-distance runner women athletes participating in training programs and having no or very mild cardiac morphologic alterations and were compared with those in 11 healthy women active in daily life not participating in training programs. Maximal exercise tolerance was tested in both groups with a treadmill with use of the standard Bruce protocol.

RESULTS

Echocardiographic left ventricular mass index and mitral and pulmonary flow patterns in athletes and controls were similar while they were supine. Major (P<.01) percent variations and differences between athletes and controls with standing were smaller decrease in right (-12% +/- 5% vs -29% +/- 5%) and left ventricular (-3% +/- 1% vs -9% +/- 2%) dimensions and stroke volume (-7% +/- 4% vs -23% +/- 4%), smaller lengthening of early mitral deceleration (+7% +/- 4% vs +18% +/- 5%), and isovolumic relaxation (-3% +/- 5% vs +15% +/- 7%) times. Athletes showed greater reduction in pulmonary S wave peak velocity (-25% +/- 10% vs -12.5% +/- 7%) and time velocity integral (Si) (-50% +/- 9% vs -21% +/- 8%), greater increases in pulmonary venous diastolic (D) wave peak velocity(+20% +/- 9% vs +12% +/- 10%, meters per second), and time velocity integral (Di) (+81% +/- 16% vs +27% +/- 14%) and greater decrease of S/D(-30% +/- 6% vs -18% +/- 5%) and Si/Di (-70% +/- 10% vs -33% +/- 5%) ratios. At multivariate analysis standing Si/Di was the strongest independent predictor of better exercise tolerance (peak exercise time 1035 +/- 88 sec in athletes, 751 +/- 20 in controls).

CONCLUSIONS

Pulmonary flow analysis in athletes while standing can detect changes in diastolic function that are dissociated from apparent left ventricular morphologic alterations, are undetected in the supine position, and may, in part, determine exercise performance.