Regional differences in myocardial performance in the left ventricle of the dog.

LeWinter, Martin M.; Kent, R S; Kroener, John M.; Carew, Thomas E.; Covell, James W.

doi:10.1161/01.res.37.2.191

Cited by 163 publications

(62 citation statements)

References 32 publications

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“…In line with previous reports [21,22], our results emphasize the concept that considering the myocardium as a uniformly functioning tissue might be misleading. Consequently, each portion of the left ventricular wall might have metabolic and perfusion needs which are specific in magnitude [23,24].…”

Section: Discussionsupporting

confidence: 92%

Mismatch between insulin-mediated glucose uptake and blood flow in the heart of patients with Type II diabetes

et al. 2002

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Aims/hypothesis. We investigated the effect of physiological hyperinsulinaemia on global and regional myocardial blood flow and glucose uptake in five patients with Type II (non-insulin-dependent) diabetes mellitus and seven healthy control subjects. Methods. Myocardial blood flow was assessed by positron emission tomography with oxygen-15 labelled water (H 2 15 O) either before or after 1 h of euglycaemic hyperinsulinaemia. Myocardial glucose uptake was assessed by positron emission tomography and fluorine-18 labelled fluorodeoxyglucose ( 18 FDG). Results. During hyperinsulinaemia, myocardial blood flow increased from 0.91±0.03 to 1.00±0.03 ml . min -1 . g -1 in control subjects (p<0.005) and from 0.81±0.02 to 0.95±0.04 ml . min -1. g -1 in diabetic patients (p<0.0005). Corresponding glucose uptakes were 0.56±0.01 and 0.36±0.02 µmol . min -1. g -1 (p<0.0001), respectively. During hyperinsulinaemia, the regional distribution of myocardial blood flow and glucose uptake showed higher values in the septum and anterolateral wall (short axis) and in the mid-ventricle (long axis) in control subjects, and insulin action was circumscribed to these regions. In diabetic patients, the regional distribution of glucose uptake was similar; however, insulin-induced increase of myocardial blood flow was mainly directed to the postero-inferior areas (short axis) and to the base (long axis) of the heart, thus cancelling the predominance of the anterior wall observed before insulin administration. Conclusion/interpretation. These results provide evidence that insulin-mediated regulation of global myocardial blood flow is preserved in Type II diabetic patients. In contrast, the regional re-distribution of myocardial blood flow induced by insulin is directed to different target areas when compared with healthy subjects, thereby resulting in a mismatch between blood flow and glucose metabolism. [Diabetologia (2002[Diabetologia ( ) 45:1404[Diabetologia ( -1409 Keywords Insulin, diabetes, myocardial glucose metabolism, myocardial perfusion, positron emission tomography. The availability of non-invasive quantification of myocardial blood flow (MBF) with positron emission tomography (PET) has re-opened the long debated issue concerning the role of insulin in the regulation of myocardial perfusion. A better understanding of this issue carries important pathophysiological implications on the relation between insulin resistance and enhanced cardiovascular risk. In previous studies [1,2,3,4,5,6], the use of invasive techniques and/or anaesthesia could have introduced confounding factors, such as variable degrees of sympathetic activation and circulating NEFA concentrations. Using PET and oxygen-15 labelled water, we have shown that in healthy

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Section: Discussionsupporting

confidence: 92%

Mismatch between insulin-mediated glucose uptake and blood flow in the heart of patients with Type II diabetes

et al. 2002

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“…The variations that occur in the myocardium in metabolic rate (Griggs et al 1972, Dunn andGriggs 1975), oxygenation (Gamble et al 1974;Schubert et al 1978;Weiss and Sinha 1978), and myocardial fiber shortening (LeWinter et al 1975) have become generally recognized. Similarly, the spatial heterogeneity of regional myocardial blood flow has been clearly demonstrated with indicator dilution methods (Bassingthwaighte et al 1972;Rose and Goresky 1976;Roselli and Harris 1979) and with the microsphere technique (Yipintsoi et al 1973;Falsetti et al 1975;Marcus et al 1977;Sestier et al 1978).…”

Section: Discussionmentioning

confidence: 99%

Temporal fluctuations in regional myocardial flows

King

Bassingthwaighte

1989

Pflugers Arch.

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Considerable spatial heterogeneity has been observed in regional myocardial blood flow in isolated hearts and in both anesthetized and conscious animals. In order to study how local blood flow varies with time, the data obtained by King et al. (1985) from ten awake, healthy baboons were analyzed to estimate the role of temporal fluctuations. Four to six distributions of regional flows were estimated at intervals of 4 min to 27 h, using 15 μ diameter microspheres and dividing each heart into 204 locatable pieces (average piece mass = 0.17 g). The technique averages over the 40 s of the injection giving no measure of fluctuations over a few seconds. The temporal variation in regional blood flow, expressed as the relative dispersion (SD/mean) of the temporally separated measurements about the mean flow for each piece and corrected for methodological noise, was 12% for the whole heart (10828 observations). For the left ventricle, the temporal variation was 10% (8806 observations), for the right ventricle 14% (1455 observations), and for the atria 22% (567 observations). On a relative basis, temporal fluctuation was greatest in regions having low flows. Since the magnitude of the changes in flow distributions was the same after 4 min as it was in several hours, we conclude that much of the "twinkling" is a high frequency phenomenon occurring over seconds to a few minutes. Further, it is concluded that regional myocardial blood flow in conscious primates is relatively stable with time, temporal fluctuations causing only about one third of the variation between regions.

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“…These investigators, and Liedke et al (17), by using angiographic techniques, showed greater shortening at the apex compared with the base of the LV. With dimension gauges implanted at the midwall in the direction of the midwall myofibers, shortening was found to be greatest in the apex (ϳ20%) and less at the midwall and base of the ventricle (16). In the transplanted human heart, longitudinal shortening tended to be greater on the posterior wall and approximately equal to circumferential shortening at anterior locations (11).…”

Section: Regional End-systolic Strains and Effects Of Afterloadmentioning

confidence: 95%

Contribution of laminar myofiber architecture to load-dependent changes in mechanics of LV myocardium

Takayama

Costa

Covell

2002

American Journal of Physiology-Heart and Circulatory Physiology

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Takayama, Yasuo, Kevin D. Costa, and James W. Covell. Contribution of laminar myofiber architecture to load-dependent changes in mechanics of LV myocardium. Am J Physiol Heart Circ Physiol 282: H1510-H1520, 2002; 10.1152/ajpheart.00261.2001.-The ventricular myocardium consists of a syncytium of myocytes organized into branching, transmurally oriented laminar sheets approximately four cells thick. When systolic deformation is expressed in an axis system determined by the anatomy of the laminar architecture, laminar sheets of myocytes shear and laterally extend in an approximately radial direction. These deformations account for ϳ90% of normal systolic wall thickening in the left ventricular free wall. In the present study, we investigated whether the changes in systolic and diastolic function of the sheets were sensitive to alterations in systolic and diastolic load. Our results indicate that there is substantial reorientation of the laminar architecture during systole and diastole. Moreover, this reorientation is both site and load dependent. Thus as end-diastolic pressure is increased and the left ventricular wall thins, sheets shorten and rotate away from the radial direction due to transverse shearing, opposite of what occurs in systole. Both mechanisms of thickening contribute substantially to normal left ventricular wall function. Whereas the relative contributions of shear and extension are comparable at the base, sheet shear is the predominant factor at the apex. The magnitude of shortening/extension and shear increases with preload and decreases with afterload. These findings underscore the essential contribution of the laminar myocardial architecture for normal ventricular function throughout the cardiac cycle. myocardium; wall thickening; systole; diastole THE VENTRICULAR MYOCARDIUM consists of a syncytium of myocytes organized into branching transmurally oriented laminar sheets approximately four cells thick (14). Recent evidence indicates that this laminar structure contributes importantly to systolic function. When systolic deformation is expressed in an axis system determined by the anatomy of the laminar architecture, laminar sheets of myocytes shear and laterally extend in an approximately radial direction. These deformations account for ϳ90% of normal systolic wall thickening in the left ventricular (LV) free wall. In a recent study (5) from this laboratory, we found regional variations in the relative contribution of sheet extension and shear to wall thickening. In the free wall of the ventricle, sheet extension accounted for the majority of wall thickening, whereas in the septum, sheet shear was the predominant factor. Systolic wall thickening is a commonly employed index of regional myocardial performance (8) in both clinical and experimental studies. However, wall thickening varies both transmurally and regionally (7). These variations were reported in clinical studies (3) using magnetic resonance imaging (MRI). Moreover, Villarreal et al. (36) have shown regional variations in the sensit...

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Regional differences in myocardial performance in the left ventricle of the dog.

Cited by 163 publications

References 32 publications

Mismatch between insulin-mediated glucose uptake and blood flow in the heart of patients with Type II diabetes

Mismatch between insulin-mediated glucose uptake and blood flow in the heart of patients with Type II diabetes

Temporal fluctuations in regional myocardial flows

Contribution of laminar myofiber architecture to load-dependent changes in mechanics of LV myocardium

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