Collagen remodeling and changes in LV function during development and recovery from supraventricular tachycardia

1991 ◽  
Vol 261 (2) ◽  
pp. H308-H318 ◽  
Author(s):  
F. G. Spinale ◽  
M. Tomita ◽  
J. L. Zellner ◽  
J. C. Cook ◽  
F. A. Crawford ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Supraventricular Tachycardia ◽  
Recovery Period ◽  
Left Ventricular ◽  
Lv Function ◽  
Atrial Pacing ◽  
Early Recovery ◽  
Lv Dysfunction ◽  
Stiffness Constant ◽  
Transmission Electron

Chronic supraventricular tachycardia (SVT) causes left ventricular (LV) dYsfunction and dilatation. Termination of SVT appears to improve symptoms of congestive heart failure. However, the structural events that occur during development and regression of SVT-induced cardiomyopathy are unknown. Accordingly, LV function (simultaneous echocardiogram-catheterization) and collagen content and distribution were measured in pigs (23-25 kg) assigned to three groups: 1) rapid atrial pacing (240 beats/min) for 3 wk (SVT, n = 10); 2) SVT for 3 wk, followed by deactivation of the pacemaker and a 4-wk recovery period (PST, n = 9); and 3) sham-operated controls (CON, n = 10). LV fractional shortening was 30 +/- 2% in CON, fell to 13 +/- 2% with SVT (P less than 0.05), and returned to CON values with PST (31 +/- 2%). SVT resulted in significantly increased LV end-diastolic dimension compared with CON (4.9 +/- 0.3 vs. 3.5 +/- 0.2 cm, P less than 0.05) and no change in LV wt/body wt (2.7 +/- 0.2 vs. 2.6 +/- 0.2 g/kg, P = 0.85). Termination of SVT (PST) resulted in development of hypertrophy, LV mass increased to 3.50 +/- 0.3 g/kg (P less than 0.05 vs. CON). With the use of pressure-dimension-thickness relations during diastole, the regional chamber stiffness constant (Kc) was computed. Kc was unchanged by SVT compared with CON (5.3 +/- 1.4 vs. 3.7 +/- 0.5, P greater than 0.35) but increased with PST (7.4 +/- 0.6, P less than 0.05). LV hydroxyproline content significantly fell with SVT compared with CON (2.24 +/- 0.58 vs. 2.68 +/- 0.45 mg/g dry wt, P less than 0.05, respectively) and significantly increased with PST (3.68 +/- 0.85 mg/g dry wt, P less than 0.05). With the use of transmission electron microscopy, collagen fibril diameter was reduced with SVT compared with CON (1.45 +/- 0.5 vs. 1.7 +/- 0.5 microns, P less than 0.05) and increased with PST (3.3 +/- 1.4 microns, P less than 0.05). Scanning electron microscopy revealed disruption of collagen struts between adjacent SVT myocytes and a thickened collagen weave with PST. Thus chronic SVT resulted in systolic and diastolic dysfunction and reduced collagen support of adjoining myocytes. Early recovery from SVT was associated with LV hypertrophy, increased collagen, and increased LV stiffness.

LV and myocyte structure and function after early recovery from tachycardia-induced cardiomyopathy

1995 ◽  
Vol 268 (2) ◽  
pp. H836-H847 ◽  
Author(s):  
F. G. Spinale ◽  
H. H. Holzgrefe ◽  
R. Mukherjee ◽  
S. R. Arthur ◽  
M. J. Child ◽  
...  
Keyword(s):  
Ejection Fraction ◽  
Contractile Function ◽  
Recovery Period ◽  
Wall Stress ◽  
Left Ventricular ◽  
Lv Function ◽  
Early Recovery ◽  
End Diastolic Volume ◽  
Lv Mass ◽  
Lv Ejection Fraction

Left ventricular (LV) function and mass were measured in six conscious dogs at weekly intervals during the progression of tachycardia-induced dilated cardiomyopathy (DCM) and during a 1-mo recovery period from DCM (post-DCM). LV end-diastolic volume and LV wall stress increased and LV ejection fraction decreased with each week of pacing. Despite the increased LV wall stress, LV mass did not change during the progression of tachycardia DCM. One week post-DCM resulted in an improved LV ejection fraction and normalization of neurohormonal profiles. However, 1 wk post-DCM was accompanied by a 26% increase in LV mass and persistent LV chamber dilation. Isolated myocyte function was examined and compared with that in six normal control dogs. Myocyte percent and myocyte velocity of shortening were 19 and 32% lower, respectively, in the post-DCM group compared with controls. Thus termination of the tachycardia subsequent to the development of DCM resulted in persistent LV chamber dilation and abnormalities in myocyte contractile function. The improved LV pump function with early recovery from tachycardia-induced DCM was mediated by LV hypertrophy and a subsequent reduction in LV wall stress rather than a normalization of LV geometry and myocyte contractile function.

Urine Albumin to Creatinine Ratio and Echocardiographic Left Ventricular Structure and Function in Patients with Essential Hypertension

2011 ◽  
Vol 9 (2) ◽  
pp. 90 ◽  
Author(s):  
Rohola Hemmati ◽  
Mojgan Gharipour ◽  
Hasan Shemirani ◽  
Alireza Khosravi ◽  
Elham Khosravi ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Peak Velocity ◽  
Left Ventricular ◽  
Lv Function ◽  
Creatinine Ratio ◽  
Uncomplicated Hypertension ◽  
Urine Albumin ◽  
Lv Dysfunction ◽  
Mitral Annulus Velocity ◽  
Lv Mass

Background:Appearance of microalbuminuria, particularly in patients with hypertension, might be associated with a higher prevalence of left ventricular (LV) dysfunction and geometric abnormalities. This study was undertaken to determine whether high urine albumin to creatinine ratio (UACR) as a sensitive marker for microalbuminuria can be associated with LV hypertrophy (LVH) and systolic and diastolic LV dysfunction.Methods:The study population consisted of 125 consecutive patients with essential uncomplicated hypertension. Urine albumin and creatinine concentration was determined by standard methods. LVH was defined as a LV mass index >100 g/m2 of body surface area in women and >130 g/m2 in men. Echocardiographic LV systolic and diastolic parameters were measured.Results:The prevalence of microalbuminuria in patients with essential hypertension was 5.6 %. UACR was significantly no different in patients with LVH than in patients with normal LV geometry (21.26 ± 31.55 versus 17.80 ± 24.52 mg/mmol). No significant correlation was found between UACR measurement and systolic and diastolic function parameters, including early to late diastolic peak velocity (E/A) ratio (R=-0.192, p=0.038), early diastolic peak velocity to early mitral annulus velocity (E/E') ratio (R=-0.025, p=0.794), LV ejection fraction (R=0.008, p=0.929), and LV mass (R=-0.132, p=0.154). According to the receiver operator characteristic (ROC) curve analysis, UACR measurement was not an acceptable indicator of LVH with areas under the ROC curves 0.514 (95 % confidence interval 0.394–0.634). The optimal cut-off value for UACR for predicting LVH was identified at 9.4, yielding a sensitivity of 51.6 % and a specificity of 48.3 %.Conclusion:In patients with uncomplicated essential hypertension, abnormal systolic and diastolic LV function and geometry cannot be effectively predicted by the appearance of microalbuminuria.

scholarly journals Effect of cardiosphere-derived cells on segmental myocardial function after myocardial infarction: ALLSTAR randomised clinical trial

Open Heart ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. e001614
Author(s):  
Mohammad R Ostovaneh ◽  
Raj R Makkar ◽  
Bharath Ambale-Venkatesh ◽  
Deborah Ascheim ◽  
Tarun Chakravarty ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Clinical Trial ◽  
Myocardial Function ◽  
Randomised Clinical Trial ◽  
Scar Tissue ◽  
Left Ventricular ◽  
Lv Function ◽  
Cardiac Events ◽  
Lv Dysfunction ◽  
Registration Number

BackgroundMost cell therapy trials failed to show an improvement in global left ventricular (LV) function measures after myocardial infarction (MI). Myocardial segments are heterogeneously impacted by MI. Global LV function indices are not able to detect the small treatment effects on segmental myocardial function which may have prognostic implications for cardiac events. We aimed to test the efficacy of allogeneic cardiosphere-derived cells (CDCs) for improving regional myocardial function and contractility.MethodsIn this exploratory analysis of a randomised clinical trial, 142 patients with post-MI with LVEF <45% and 15% or greater LV scar size were randomised in 2:1 ratio to receive intracoronary infusion of allogenic CDCs or placebo, respectively. Change in segmental myocardial circumferential strain (Ecc) by MRI from baseline to 6 months was compared between CDCs and placebo groups.ResultsIn total, 124 patients completed the 6-month follow-up (mean (SD) age 54.3 (10.8) and 108 (87.1%) men). Segmental Ecc improvement was significantly greater in patients receiving CDC (−0.5% (4.0)) compared with placebo (0.2% (3.7), p=0.05). The greatest benefit for improvement in segmental Ecc was observed in segments containing scar tissue (change in segmental Ecc of −0.7% (3.5) in patients receiving CDC vs 0.04% (3.7) in the placebo group, p=0.04).ConclusionsIn patients with post-MI LV dysfunction, CDC administration resulted in improved segmental myocardial function. Our findings highlight the importance of segmental myocardial function indices as an endpoint in future clinical trials of patients with post-MI.Trial registration numberNCT01458405.

Regulation of components of the brain and cardiac renin-angiotensin systems by 17β-estradiol after myocardial infarction in female rats

2006 ◽  
Vol 291 (1) ◽  
pp. R155-R162 ◽  
Author(s):  
Stephanie A. Dean ◽  
Junhui Tan ◽  
Roselyn White ◽  
Edward R. O’Brien ◽  
Frans H. H. Leenen
Keyword(s):  
Myocardial Infarction ◽  
Left Ventricular ◽  
Female Rats ◽  
Lv Function ◽  
Coronary Artery Ligation ◽  
Brain Nuclei ◽  
Renin Angiotensin ◽  
Lv Dysfunction ◽  
17Β Estradiol ◽  
The Brain

The present study tested the hypothesis that 17β-estradiol (E2) inhibits increases in angiotensin-converting enzyme (ACE) and ANG II type 1 receptor (AT1R) in the brain and heart after myocardial infarction (MI) and, thereby, inhibits development of left ventricular (LV) dysfunction after MI. Age-matched female Wistar rats were treated as follows: 1) no surgery (ovary intact), 2) ovariectomy + subcutaneous vehicle treatment (OVX + Veh), or 3) OVX + subcutaneous administration of a high dose of E2 (OVX + high-E2). After 2 wk, rats were randomly assigned to coronary artery ligation (MI) and sham operation groups and studied after 3 wk. E2 status did not affect LV function in sham rats. At 2–3 wk after MI, impairment of LV function was similar across MI groups, as measured by echocardiography and direct LV catheterization. LV ACE mRNA abundance and activity were increased severalfold in all MI groups compared with respective sham animals and to similar levels across MI groups. In most brain nuclei, ACE and AT1R densities increased after MI. Unexpectedly, compared with the respective sham groups the relative increase was clearest (20–40%) in OVX + high-E2 MI rats, somewhat less (10–15%) in ovary-intact MI rats, and least (<10–15%) in OVX + Veh MI rats. However, because in the sham group brain ACE and AT1R densities increased in the OVX + Veh rats and decreased in the OVX + high-E2 rats compared with the ovary-intact rats, actual ACE and AT1R densities in most brain nuclei were modestly higher (<20%) in OVX + Veh MI rats than in the other two MI groups. Thus E2 does not inhibit upregulation of ACE in the LV after MI and amplifies the percent increases in ACE and AT1R densities in brain nuclei after MI, despite E2-induced downregulation in sham rats. Consistent with these minor variations in the tissue renin-angiotensin system, during the initial post-MI phase, E2 appears not to enhance or hinder the development of LV dysfunction.

Impact of Valve Surgery on Serum Osteopontin Levels in Patients with Mitral Regurgitation

Cardiology ◽  
2015 ◽  
Vol 130 (2) ◽  
pp. 82-86
Author(s):  
H.M. Gunes ◽  
G.B. Guler ◽  
E. Guler ◽  
G.G. Demir ◽  
S. Hatipoglu ◽  
...  
Keyword(s):  
Mitral Regurgitation ◽  
Left Ventricular ◽  
Valve Surgery ◽  
Lv Function ◽  
Vena Contracta ◽  
Atherosclerotic Lesions ◽  
Lv Dysfunction ◽  
Echocardiographic Parameters ◽  
Artery Disease ◽  
The Impact

Objective: Osteopontin (OPN), a sialoprotein present within atherosclerotic lesions, especially in calcified plaques, is linked to the progression of coronary artery disease and heart failure. We assessed the impact of valve surgery on serum OPN and left ventricular (LV) function in patients with mitral regurgitation (MR). Methods: Thirty-two patients with severe MR scheduled for surgery were included in the study. Echocardiography markers were assessed preoperatively and at 3 months following the surgery and matched with the serum OPN levels. Results: Valve surgery was associated with a reduction of the ejection fraction (EF) from 55.2 ± 6.3 to 48.8 ± 7.1% after surgery, p < 0.001. Following surgery, the OPN level was significantly higher than preoperatively (mean 245, range 36-2,284 ng/ml vs. 76, 6-486 ng/ml, p = 0.007). Preoperative OPN exhibited a slight negative correlation with the EF (r = -0.35, p = 0.04), and a moderate correlation with vena contracta (r = -0.38, p = 0.02). There were no other meaningful correlations between conventional echocardiographic parameters and OPN. Conclusion: Following valve surgery due to severe MR, patients exhibited a decrease in EF and an increase in OPN levels. The assessment of preoperative OPN failed to strongly predict probable LV dysfunction.

Abstract 14119: Contrasting Effects of Exercise Training After Acute Myocardial Infarction versus Aortic Stenosis Depend Critically on the Regulation of Endothelial Nitric Oxide Synthase

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Yanti Octavia ◽  
Elza D van Deel ◽  
Monique de Waard ◽  
Martine de Boer ◽  
Dirk J Duncker
Keyword(s):  
Nitric Oxide ◽  
Myocardial Infarction ◽  
Exercise Training ◽  
Wheel Running ◽  
Left Ventricular ◽  
Lv Function ◽  
Enhanced Chemiluminescence ◽  
Lv Dysfunction ◽  
Enos Uncoupling ◽  
Endothelial Nitric Oxide

Introduction: The cardiovascular benefits of exercise training (EX) are widely appreciated. Previously we found that the cardiac effects of EX critically depend on the underlying cause of heart disease. Hypothesis: The underlying etiology determines how EX affects the endothelial nitric oxide (NO) synthase (eNOS)-mediated balance between NO and superoxide (O2-). Methods: Mice were subjected to sham surgery, myocardial infarction (MI) or transverse aortic constriction (TAC), and subsequently exposed to 8 weeks of voluntary wheel running or sedentary housing. Left ventricular (LV) function was assessed by echocardiography and hemodynamic measurements; fibrosis by Picro-sirius Red staining; peroxynitrite (ONOO-) and O2- production by luminol- and lucigenin-enhanced chemiluminescence respectively, with or without the NOS inhibitor L-NAME; eNOS uncoupling and eNOS S-glutathionylation by western blot and coimmunoprecipitation, respectively; cardiac NO by the Griess reaction. Results: EX ameliorated LV dysfunction and fibrosis in MI but not TAC (Table 1). Strikingly, O2- generation was blunted by EX in MI, but exacerbated by EX in TAC, which was largely NOS-dependent. Accordingly, eNOS uncoupling and eNOS S-glutathionylation were corrected by EX in MI but aggravated in TAC mice. In parallel, ONOO- levels was attenuated by EX in MI but aggravated by EX in TAC. Cardiac NO levels were reduced in MI and TAC and normalized by EX in MI. Conclusions: The contrasting effects of EX in MI vs TAC can be explained by the highly divergent effects of EX on eNOS regulation, resulting in blunted vs aggravated oxidative stress by EX in MI vs TAC.

Association between Serum Ferritin Level and Left Ventricular Function by Speckle Tracking Echocardiography in Patients with Thalassemia

2021 ◽  
Vol 104 (9) ◽  
pp. 1421-1427
Keyword(s):  
Serum Ferritin ◽  
Speckle Tracking ◽  
Speckle Tracking Echocardiography ◽  
Early Stage ◽  
Ferritin Level ◽  
Left Ventricular ◽  
Lv Function ◽  
Lv Dysfunction ◽  
Spearman's Rho ◽  
Spearman’S Rho

Background: Thalassemia is a common disease in Thailand. Most patients with thalassemia receive regular blood transfusion, resulting in iron accumulation in the body. Ferritin levels are associated with iron accumulation in vital organs of patients with thalassemia. The relationship between the ferritin levels and left ventricular (LV) function in these patients showed no relationship in most data, but all data were measured by conventional echocardiography. Currently, LV function can be measured by more advanced methods, such as the speckle tracking echocardiography, which demonstrates high accuracy in detecting early-stage LV dysfunction. Objective: To investigate the association between the serum ferritin level and LV function by speckle tracking echocardiography in patients with thalassemia. Materials and Methods: The present study was a cross-sectional analytic study that enrolled patients with thalassemia in the Faculty of Medicine, Vajira Hospital, between January and December 2019. Each participants provided an informed consent. Serum ferritin, conventional echocardiography, and speckle tracking echocardiography using global longitudinal strain [GLS] parameters were collected. Results: Among 45 participants, 33 had transfusion-dependent thalassemia (TDT), and 12 had non-transfusion-dependent thalassemia (NTDT). Female participants accounted for 64.4% with 29 patients. The mean age was 35.51±13.81 years, and participants had no other systemic diseases. The median serum ferritin was 1,159 ng/dL with a range of 638 to 1,983. The mean values for GLS and LVEF by biplane were −22.97±2.20% and 63.90±7.62%, respectively. Serum ferritin was not significantly related to GLS (Spearman’s rho 0.164, 95% CI −0.136 to 0.437, p=0.280). In the TDT group, ferritin was significantly related to GLS (Spearman’s rho 0.405, 95% CI 0.072 to 0.657, p=0.019), whereas in the NTDT group, such relationship was insignificant (Spearman’s rho −0.394, 95% CI 0.790 to 0.232, p=0.205). Conclusion: Serum ferritin and speckle tracking echocardiography in patients with thalassemia are not significantly associated. Therefore, serum ferritin should not be a single candidate for detecting early-stage LV dysfunction. As a result, using various measurements remains the best option. Keywords: Ferritin; Speckle tracking echocardiography; Thalassemia; Echocardiography

scholarly journals Bridge to recovery with Berlin Heart EXCOR in children <10 kg with dilated cardiomyopathy: a histological analysis

2020 ◽  
Vol 58 (2) ◽  
pp. 253-260 ◽  
Author(s):  
Yuji Tominaga ◽  
Takayoshi Ueno ◽  
Takashi Kido ◽  
Tomomitsu Kanaya ◽  
Jun Narita ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Left Ventricular ◽  
Lv Function ◽  
Vascular Density ◽  
Bridge To Recovery ◽  
High Power Field ◽  
Lv Dysfunction ◽  
Paediatric Patients ◽  
Berlin Heart ◽  
Recovery Group

Abstract OBJECTIVES This study aimed to identify the histological characteristics associated with bridge to recovery using Berlin Heart EXCOR® (BHE) in paediatric patients &lt;10 kg with dilated cardiomyopathy. METHODS Of the 10 consecutive patients &lt;10 kg with dilated cardiomyopathy who underwent BHE implantation between 2013 and 2018, 4 patients showed improvement in left ventricular (LV) function, resulting in successful BHE explantation (recovery group). The remaining 6 patients showed persistent LV dysfunction and underwent heart transplantation (non-recovery group). The following variables were compared between the 2 groups: (i) histological findings in LV myocardium obtained at BHE implantation and (ii) LV function after BHE implantation assessed with echocardiography and cardiac catheterization. RESULTS The degree of myocardial fibrosis was significantly lower, and the capillary vascular density was significantly higher in the recovery group than in the non-recovery group [16% (standard deviation 5.9%) vs 28% (5.9%), P = 0.021, and 65 (11) vs 43 (18) units/high-power field, P = 0.037, respectively]. The changes during 3 months after BHE implantation in LV diastolic dimension (z-score) and ejection fraction were significantly greater in the recovery group than in the non-recovery group [−9.6 (3.5) vs −3.6 (4.5), P = 0.045, and 36% (13%) vs 13% (13%), P = 0.032, respectively]. CONCLUSIONS In paediatric patients &lt;10 kg with dilated cardiomyopathy, bridge to recovery with BHE implantation was achieved in patients with less injured LV myocardial histology at BHE implantation.

scholarly journals Valve Replacement for Aortic Stenosis in Patients With Poor Left Ventricular Function

Circulation ◽  
1999 ◽  
Vol 100 (suppl_2) ◽  
Author(s):  
Julian Collinson ◽  
Michael Henein ◽  
Marcus Flather ◽  
John R. Pepper ◽  
Derek G. Gibson
Keyword(s):  
Aortic Stenosis ◽  
Systolic Function ◽  
Left Ventricular ◽  
Lv Function ◽  
Valve Prosthesis ◽  
Transthoracic Doppler Echocardiography ◽  
Early Improvement ◽  
Lv Dysfunction ◽  
Lv Systolic Function ◽  
Fractional Shortening

Background —Long-standing aortic stenosis causes significant left ventricular (LV) dysfunction, which may progress irreversibly. In many cases, LV function can be salvaged by aortic valve surgery, although debate exists regarding the best valve prosthesis to use. Methods and Results —We studied 33 patients retrospectively who had significant aortic stenosis and impaired LV systolic function, as assessed by transthoracic Doppler echocardiography. Patients were assessed preoperatively and before discharge from the hospital. A total of 20 patients received a stentless (homograft or Toronto) valve, and 13, a stented valve. No patient had significant aortic regurgitation or other valvular disease. Preoperatively, fractional shortening was 18.8±5.5% in the stentless group and 18.6±3.8% in the stented group. Postoperatively, it was 25.6±6.9% ( P <0.001 compared with baseline) and 17.0±2.8%, respectively ( P <0.001 compared with stentless group). Fractional shortening improved because of a reduction in LV end-systolic and end-diastolic dimensions in the stentless group. Systolic long axis function at the LV free wall also recovered, with an increase in systolic excursion and both peak shortening and lengthening rates. No change was noted in mitral valve Doppler patterns. Conclusions —Patients who received a stentless valve demonstrated a significantly greater early improvement in LV systolic function compared with those who received a stented valve.

Tachycardia-induced cardiomyopathy: effects on blood flow and capillary structure

1991 ◽  
Vol 261 (1) ◽  
pp. H140-H148 ◽  
Author(s):  
F. G. Spinale ◽  
J. L. Zellner ◽  
M. Tomita ◽  
G. E. Tempel ◽  
F. A. Crawford ◽  
...  
Keyword(s):  
Blood Flow ◽  
Capillary Density ◽  
Left Ventricular ◽  
Lv Function ◽  
Atrial Pacing ◽  
Capillary Structure ◽  
Potential Factor ◽  
Rapid Pacing ◽  
Tachycardia Induced Cardiomyopathy ◽  
Fractional Shortening

Chronic supraventricular tachycardia (SVT) causes a dilated cardiomyopathy. A potential factor contributing to the development of SVT-induced cardiomyopathy is abnormal myocardial blood flow (MBF). The purpose of this study was to relate changes in left ventricular (LV) function, MBF, and capillary structure with the development of SVT-induced cardiomyopathy. LV function and MBF were measured in two groups of conscious pigs: sham control (CON; n = 8) and after 3 wk of atrial pacing (SVT; 240 beats/min; n = 8) using echocardiography-catheterization and microspheres. Measurements were made under three states: 1) at rest with a basal heart rate, 2) during rapid atrial pacing (240 beats/min), and 3) during adenosine infusion (1.5 microM.kg-1.min-1) without pacing. LV capillary density, diameter, wall thickness, and capillary-myocyte distance were measured in four additional pigs from each group. LV fractional shortening was lower, and left atrial pressure was significantly higher in the SVT group compared with CON at rest, during pacing, and with adenosine (P less than 0.05). In the CON group, average LV-MBF at rest was 2.0 +/- 0.2 ml.min-1.g-1, increased with pacing to 3.0 +/- 0.2 ml.min-1.g-1 (P less than 0.05), and increased further with adenosine to 4.1 +/- 0.3 ml.min-1.g-1 (P less than 0.05). In all states, SVT LV-MBF was significantly reduced vs. CON (P less than 0.05); SVT LV-MBF was 0.8 +/- 0.2 ml.min-1.g-1 at rest, increased to 1.3 +/- 0.3 ml.min-1.g-1 with rapid pacing (P less than 0.05), and remained unchanged during adenosine (1.3 +/- 0.4 ml.min-1.g-1).(ABSTRACT TRUNCATED AT 250 WORDS)

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