Absolute quantification of high energy phosphate metabolites in normal, hypertrophied and failing human myocardium.
Explore the source record for details and available documents.
Adenosine Triphosphate↗
Biomedical subjects
S Neubauer
Publications and source records attributed to S Neubauer.
Cardiac magnetic resonance spectroscopy: potential clinical applications.
MR spectroscopy is the only method for non-invasive detection of various aspects of cardiac metabolism in humans. While the 1H nucleus of water and fat molecules is the signal source for MR imaging, the MR spectroscopic technique allows for the study of a number of other nuclei, such as 13C, 19F, 23Na, 31P, 39K and 87Rb. Clinical applications presently are confined to the 31P nucleus. 31P-MR spectroscopy allows the non-invasive study of cardiac high-energy phosphate metabolites ATP and phosphocreatine. The phosphocreatine/ATP ratio is considered an index of the energetic state of the heart. Possible clinical indications include heart failure, valve disease and coronary artery disease. In heart failure, the phosphocreatine/ATP ratio is reduced and correlates with clinical severity, ejection fraction and prognosis. In mitral and aortic valve disease, a reduced phosphocreatine/ATP ratio may indicate the optimum timing for valve replacement. In coronary artery disease, a regional decrease of phosphocreatine during stress ("biochemical ergometry") may indicate local ischemia. Furthermore, absolute quantification of high-energy phosphates may allow diagnosis of myocardial viability. Major technical developments, leading to improved spatial and temporal resolution will be necessary to establish MR spectroscopy as a routine clinical tool.
Angioplasty, Balloon, Coronary↗
[Evaluating signal intensity of movement-impaired myocardial segments in MR delayed images after administration of Gd-DTPA. Correlation of regional increase in contraction after revascularization].
PURPOSE: The aim of the study was to correlate delayed contrast enhancement of dysfunctional regions of the myocardium after injection of Gd-DTPA with the improvement of regional contractility 3 months after revascularization. MATERIAL AND METHODS: Eleven patients with coronary artery disease and wall motion abnormalities underwent MR imaging before and 3 months after revascularization therapy (PTCA or CABG). Short-axis images were acquired using a cine gradient echo sequence. After revascularization, a representative slice was analyzed 14 +/- 1 min after injection of 0.1 mmol/kg Gd-DTPA using a T1-weighted turbo fast low-angle shot sequence. Improved systolic wall thickening 3 months after revascularization served as criterion of viability and was correlated with delayed contrast enhancement patterns. RESULTS: After revascularization, 6 patients showed complete recovery of the dysfunctional area, 1 patient partial recovery, and 4 patients remained unchanged. All 4 patients with persisting wall motion abnormalities, 1/6 patients with recovery and the patient with partial recovery revealed a delayed enhancement. CONCLUSIONS: Three months after revascularization, delayed enhancement of dysfunctional myocardium is evident in patients without regional wall motion improvement, while the lack of delayed enhancement correlates with improvement of regional contractility.
Adult↗
[Cardiac energy metabolism in heart valve diseases with 31P MR spectroscopy].
PURPOSE: Heart valve disease combined with left ventricular hypertrophy leads to derangements in cardiac energy metabolism, which can be detected non-invasively by 31P-MR-spectroscopy. The purpose of the present study was to examine whether the derangements in cardiac metabolism are reversible after surgical valve replacement. PATIENTS AND METHODS: 10 healthy volunteers and 10 patients with aortic stenosis (pressure gradients > 60 mmHg) were included. For assessment of energy metabolism, 31P-MR spectra were obtained with a double oblique 3D-CSI technique (voxel size 25 cm3). In 5 of 10 patients, follow-up examination was performed 3 months after surgical valve replacement (SVR). Left ventricular (LV) function was analyzed by cine MRI. RESULTS: Before SVR the myocardial phosphocreatine to adenosinetriphosphate (PCr-ATP) ratio was significantly (p = 0.0002) reduced to 0.80 +/- 0.25 in patients compared to 1.65 +/- 0.21 in volunteers. 3 months after SVR, LV mass had significantly (p = 0.04) decreased from 238 +/- 33 g to 206 +/- 47 g. At the same time a significant (p = 0.04) increase of the PCr-ATP ratio from 0.80 +/- 0.25 to 1.28 +/- 0.22 was observed. A slight, but not significant, reduction of the phosphodiester ATP ratio was observed before SVR, with a trend towards normalization after SVR. CONCLUSIONS: After SVR, the deranged energy metabolism shows a trend towards normalization. Further follow-up is necessary to determine whether complete normalization of the energetic derangement can be observed over longer periods of time following SVR.
Adult↗
[Treatment outcomes in primary and secondary retroperitoneal fibrosis].
Retroperitoneal fibrosis (RPF) is an uncommon inflammatory disease of the retroperitoneum leading to extensive fibrosis with consecutive obstruction of adjacent organs, namely the ureters. Since no consensus on the standard therapy exists, aim of the current study was to evaluate the outcome of 39 patients with RPF. Between 1986 and 1997 39 cases of RPF were diagnosed: 21 cases had primary RPF and 18 patients had secondary RPF after aortofemoral graft (n = 13), radiation (n = 2), or prior retroperitoneal surgery (n = 2). 21 patients demonstrated unilateral and 16 cases had bilateral hydronephrosis, in 2 patients no dilatation was observed. In 28 cases (n = 12 primary RPF, n = 16 secondary RPF) initial management consisted of DJ-stent placement, whereas in 11 cases (n = 9 primary RPF, n = 2 secondary RPF) percutaneous nephrostomy had to be placed. All patients received oral immunosuppressive agents (prednisolone 1 mg/kg, azathioprine 1 mg/kg/day) for 3 months before reevaluation was performed. In case of complete remission, immunosuppressive medication was continued for another 3 months, in case of stable disease or progression surgery was performed. In 26 cases (n = 15 primary RPF, n = 11 secondary RPF) ureterolysis with intraperitoneal displacement and omental wrapping was performed. 3 patients demonstrated complete remission after oral prednisolone/azathioprine; in 2 cases RPF presented as pelvic mass and was resected followed by immunosuppressive therapy, in another 2 cases bilateral ileal replacement of the ureters had to be performed and 4 cases remained on DJ-stents and nephrostomy, resp. Postoperatively, all patients with primary RPF were continued on immunsuppressive medication for another 3 months. After a follow-up of 6 to 120 months only 3 patients developed a retroperitoneal recurrence and were treated by unilateral nephrectomy or DJ stent placement (n = 2). Our data suggest that the combination of both immunosuppressive medication and surgical management results in an excellent longterm outcome in idiopathic retroperitoneal fibrosis with a recurrence rate of only 8%. Combination therapy should be considered as therapeutic option early in the course of the disease. Primary reconstructive surgery appears to be the most promising approach in secondary retroperitoneal fibrosis with a recurrence rate of only 5%; short external compression of the ureter might be managed by endoluminal balloon dilatation.
Adult↗
[Microsurgical vasovasostomy in the age of modern reproduction medicine. A cost-benefit analysis].
WS represents the standard procedure of choice for the treatment of obstructive azoospermia following vasectomy. However, recently, ICSI has been suggested by some to represent the solution for all cases of male factor infertility regardless of its etiology based on its success rates. Therefore, we compared VVS to MESA/TESE and ICSI in terms of pregnancy, complications, and costs. Between 1/93 and 6/98 157 VVS was performed microsurgically using the 2-layer technique in 157 patients following prior vasectomy. Between 9/94 and 9/97 69 couples underwent MESA/ICSI for epididymal obstruction not amenable to micro-surgical reconstruction such as post-inflammatory obstruction and congenital absence of the vas deferens; in the same time period 42 couples underwent TESE/ICSI for azoospermia of testicular origin due to cryptorchidism, testicular atrophy, obstruction of the rete testis. In most cases MESA or TESE and ICSI were performed metachronously. Mean intervall of vasal obstruction was 7.6 (0.5-18) years; patency after VVS was 77%, pregnancy rate was 52%. Local complication rate was 4.7%, no major complications were observed. Costs per life birth after VVS were as high as 5,447,-DM or 2,800 Euro. Pregnancy rates after MESA/TESE and ICSI were 22.5% and 19.5%, respectively with 16 singletons, 3 twins and 3 abortions; local complications occurred in 3.9% of the men. Multiple birth were noticed in 15.8% following ICSI, but only in 0.7% following VVS. 5.7% and 1.4% of the female partners experienced serious complications as a mild or severe ovarian hyperstimulation-syndrome, respectively. Costs per life birth after MESA/TESE cycle were as high as 28,804,-DM or 14,100 Euro. Even in the era of ICSI microsurgical vasovasostomy represents the standard approach for obstructive azoospermia following vasectomy. Based on a cost-benefit analysis VVS is more successful in terms of pregnancy rates (52% vs. 22.5%). We conclude that MESA/ICSI should be reserved for patients not amenable for microsurgical reconstruction.
Adult↗
Altered energy metabolism after myocardial infarction assessed by 31P-MR-spectroscopy in humans.
The value of 31P-magnetic resonance spectroscopy (MRS) as a possible tool to distinguish viable from non-viable tissue after myocardial infarction was analysed in humans. Fifteen patients 3 weeks after anterior myocardial infarction were studied with breath-hold cine MRI and 3D-CSI MRS (1.5 T system). 31P-spectra were obtained from infarcted as well as non-infarcted myocardium (voxel size 25 cm3 each). Gold standard for viability was recovery of regional function, as determined by a control MRI 6 months after revascularization. Ten age-matched healthy volunteers served as control group. No significant difference was found between the phosphocreatine to adenosinetriphosphate (PCr/ ATP) ratio of volunteers (SD 1.72+/-0.31) and non-infarcted septal myocardium of patients. Cine MRI demonstrated recovery of regional function in 10 patients, i. e. 10 patients showed viable and 5 non-viable myocardium. In viable myocardium, the PCr/ATP ratio was 1.47+/-0.38 (non-significant vs volunteers; p>0.05). In the 5 patients with akinetic myocardium, PCr peaks could not be detected. Therefore, calculation of PCr/ATP ratios was not possible. However, a significant reduction of the ATP signal-to-noise ratio (SNR) was observed (2.92+/-0.73 vs 6.68+/-0.80; patients vs volunteers; p<0.05). The SNR of ATP of akinetic regions may predict recovery of function after revascularization in patients with myocardial infarction.
Adenosine Triphosphate↗
Age- and gender-specific differences in left and right ventricular cardiac function and mass determined by cine magnetic resonance imaging.
We examined possible age- and gender-specific differences in the function and mass of left (LV) and right (RV) ventricles in 36 healthy volunteers using cine gradient-recalled echo magnetic resonance imaging. Subjects were divided into four groups (nine men and nine women in each): men aged under 45 years (32 +/- 7), women aged under 45 (27 +/- 6), men aged over 45 (59 +/- 8), and women aged over 45 (57 +/- 9). Functional analysis of cardiac volume and mass and of LV wall motion was performed by manual segmentation of the endocardial and epicardial borders of the end-diastolic and end-systolic frame; both absolute and normalized (per square meter body surface area) values were evaluated. With age there was a significant decrease in both absolute and normalized LV and RV chamber volumes (EDV, ESV), while LV and RV masses remained unchanged. Gender-specific differences were found in cardiac mass and volume (for men and women, respectively: LV mass, 155 +/- 18 and 110 +/- 16 g; LV EDV, 118 +/- 27 and 96 +/- 21 ml; LV ESV, 40 +/- 13 and 29 +/- 9 ml; RV mass, 52 +/- 10 and 39 +/- 5 g; RV EDV, 131 +/- 28 and 100 +/- 23 ml; RV ESV, 53 +/- 17 and 33 +/- 15 ml). Normalization to body surface area eliminated differences in LV volumes but not those in LV mass, RV mass, or RV function. Functional parameters such as cardiac output and LV ejection fraction showed nonsignificant or only slight differences and were thus largely independent of age and gender. Intra- and interobserver variability ranged between 1.4% and 5.9% for all parameters. Cine magnetic resonance imaging thus shows age- and gender-specific differences in cardiac function, and therefore the evaluation of cardiac function in patients should consider age- and gender-matched normative values.
Adult↗
[Clinical relevance of MR spectroscopy of the heart].
MR spectroscopy is the only method that allows for the noninvasive study of cardiac metabolism in the human heart without the use of external radioactive tracers. 31P-spectroscopy allows to examine the high-energy phosphates ATP and phosphocreatine. Clinical studies with 31P-spectroscopy have focused on three areas: heart failure, valve disease and coronary artery disease. Whether MR spectroscopy will become a routine diagnostic tool in the future remains to be determined.
Energy Metabolism↗
Normal V(D)J recombination in cells from patients with Nijmegen breakage syndrome.
The majority of antigen receptor diversity in mammals is generated by V(D)J recombination. During this process DNA double strand breaks are introduced at recombination signals by lymphoid specific RAG1/2 proteins generating blunt ended signal ends and hairpinned coding ends. Rejoining of all DNA ends requires ubiquitously expressed DNA repair proteins, such as Ku70/86 and DNA ligase IV/XRCC4. In addition, the formation of coding joints depends on the function of the scid gene encoding the catalytic subunit of DNA-dependent protein kinase, DNA-PK(CS), that is somehow required for processing of coding end hairpins. Recently, it was shown that purified RAG1/2 proteins can cleave DNA hairpins in vitro, but the same activity was also described for a protein complex of the DNA repair proteins Nbs1/Mre11/Rad50. This leaves the possibility that either protein complex might be involved in coding end processing in V(D)J recombination. We have therefore analyzed V(D)J recombination in cells from patients with Nijmegen breakage syndrome, carrying a mutation in the nbs1 gene. We find that V(D)J recombination frequencies and the quality of signal and coding joining are comparable to wild-type controls, as analyzed by a cellular V(D)J recombination assay. In addition, we did not detect significant differences in CDR3 sequences of endogenous Ig lambdaL and kappaL chain gene loci cloned from peripheral blood lymphocytes of an NBS patient and of healthy individuals. These findings suggest that the Nbs1/Mre11/Rad50 complex is not involved in coding end processing of V(D)J recombination.
Ataxia Telangiectasia↗
Assessment of myocardial viability by 31P-MR-spectroscopy and 23Na-MR imaging.
Explore the source record for details and available documents.
Adenosine Triphosphate↗
[(23)sodium MRI for infarct imaging of the human heart].
PURPOSE: Sodium is elevated in acute/subacute myocardial infarction due to three distinct mechanisms: Breakdown of ion homeostasis with accumulation of intracellular sodium, extracellular edema formation and, during scar formation, increase of extracellular vs. intracellular space as cardiomyocytes are replaced by connective tissue. 23Na MRI has previously been shown to have the potential to demonstrate myocardial infarction in an animal model. Aim of this study was, therefore, to demonstrate myocardial infarction with the use of 23Na-MRI in patients. MATERIAL AND METHODS: 10 patients were examined 14 +/- 7 days after first myocardial infarction using a 23Na surface coil at 1.5 T. Double angulated short axis images of the entire heart were imaged using an ECG-triggered 3d-FLASH-sequence (FOV, 450 mm; matrix, 64 x 128; spatial resolution, 3.5 x 7 mm2; slice thickness, 16 mm; 32 acquisitions). Areas of elevated sodium signal intensity were correlated with infarct-related wall motion abnormalities imaged by Cine MRI in breathhold-technique. RESULTS: All patients showed an area of elevated sodium signal intensity that correlated well with the clinically determined localization of myocardial infarction as well as with regional wall motion abnormalities detected by Cine MRI. CONCLUSIONS: Elevated 23Na MR image signal intensity demonstrates subacute myocardial infarction in patients.
Aged↗
Developmental changes of cardiac function and mass assessed with MRI in neonatal, juvenile, and adult mice.
Cardiovascular transgenic mouse models with an early phenotype or even premature death require noninvasive imaging methods that allow for accurate visualization of cardiac morphology and function. Thus the purpose of our study was to assess the feasibility of magnetic resonance imaging (MRI) to characterize cardiac function and mass in newborn, juvenile, and adult mice. Forty-five C57bl/6 mice from seven age groups (3 days to 4 mo after birth) were studied by MRI under isoflurane anesthesia. Electrocardiogram-gated cine MRI was performed with an in-plane resolution of (78-117 microm)(2). Temporal resolution per cine frame was 8.6 ms. MRI revealed cardiac anatomy in mice from all age groups with high temporal and spatial resolution. There was close correlation between MRI- and autopsy-determined left ventricular (LV) mass (r = 0.95, SE of estimate = 9.5 mg). The increase of LV mass (range 9.6-101.3 mg), cardiac output (range 1.1-14.3 ml/min), and stroke volume (range 3. 2-40.2 microl) with age could be quantified by MRI measurements. Ejection fraction and cardiac index did not change with aging. However, LV mass index decreased with increasing age (P < 0.01). High-resolution MRI allows for accurate in vivo assessment of cardiac function in neonatal, juvenile, and adult mice. This method should be useful when applied in transgenic mouse models.
Aging↗
Analysis of first-pass and delayed contrast-enhancement patterns of dysfunctional myocardium on MR imaging: use in the prediction of myocardial viability.
OBJECTIVE: The purpose of the study was to analyze first-pass and delayed contrast-enhancement patterns of dysfunctional myocardial regions on MR imaging after injection of gadopentetate dimeglumine to predict myocardial viability in patients with coronary artery disease. SUBJECTS AND METHODS: Twelve patients with wall motion abnormalities and related coronary artery disease revealed by conventional coronary angiography underwent MR imaging at 1.5-T before and 3 months after revascularization therapy. Short-axis images were acquired using a cine gradient-echo sequence. Each slice was divided into eight segments. Overall, 73 segments with impaired contractility were imaged during the first-pass and 14 +/- 2 min after injection of 0.05-mmol/kg gadopentetate dimeglumine at a flow of 3 ml/sec using a T1-weighted turbo fast low-angle shot sequence. Improved systolic wall thickening 3 months after revascularization served as the criterion of viability. RESULTS: At study entry, 26 dysfunctional segments showed delayed hyperenhancement compared with the adjacent functional segments within the same slice, and 47 did not reveal hyperenhancement. After revascularization, 25 (96%) of the 26 hyperenhanced segments did not recover function, whereas 39 (83%) of the 47 segments without hyperenhancement showed mechanical improvement. Segment-related sensitivity and specificity for the correlation of lack of delayed hyperenhancement with myocardial viability were 39 (98%) of 40 and 25 (76%) of 33, respectively. Hypoenhancement during first-pass did not serve as a reliable criterion of viability. CONCLUSION: Evidence of delayed hyperenhancement of dysfunctional myocardium may be used to predict lack of mechanical improvement or nonviability, whereas the lack of hyperenhancement can be correlated with improvement of regional contractility or viability after revascularization.
Aged↗
31P-nuclear magnetic resonance spectroscopy of blood: a species comparison.
31P-nuclear magnetic resonance (NMR) spectroscopy isfrequently used as a tool in the study of organs from various animal species and humans. Because signals arising from the presence of blood are visible in in vivo 31P-NMR spectra of blood-filled organs, such as the heart, it is necessary to correct these spectra for the contribution of blood to the signal. It is unknown whether species differences in 31P signals of blood exist. 31P-containing metabolites of blood from various species were therefore quantified by means of 31P-NMR spectroscopy. Signals of 2,3-bisphosphoglycerate (2,3-DPG); phosphodiesters (PDE); and gamma-, alpha-, and beta-ATP were detected in all 31P-NMR spectra of blood. 2,3-DPG/ATP ratios were significantly higher in dogs, rats, and guinea pigs than in humans but lower in sheep. Pig and rabbit were the only animals with a 2,3-DPG/ATP ratio similar to that of humans. PDE levels varied among species but were significantly lower than in humans only in guinea pigs. The PDE/ATP ratio was relatively similar among all species compared with humans, except dog and guinea pig, where it was significantly higher and lower, respectively. We conclude that because of large species differences, species-specific 31P metabolite ratios should be applied for the correction of in vivo 31P-NMR spectra.
2,3-Diphosphoglycerate↗
Downregulation of the Na(+)-creatine cotransporter in failing human myocardium and in experimental heart failure.
BACKGROUND: The failing myocardium is characterized by depletion of phosphocreatine and of total creatine content. We hypothesized that this is due to loss of creatine transporter protein. METHODS AND RESULTS: Creatine transporter protein was quantified in nonfailing and failing human myocardium (explanted hearts with dilated cardiomyopathy [DCM; n=8] and healthy donor hearts [n=8]) as well as in experimental heart failure (residual intact left ventricular tissue, rats 2 months after left anterior descending coronary artery ligation [MI; n=8] or sham operation [sham; n=6]) by Western blotting. Total creatine content was determined by high-performance liquid chromatography. Donor and DCM hearts had total creatine contents of 136.4+/-6.1 and 68.7+/-4.6 nmol/mg protein, respectively (*P<0.05); creatine transporter protein was 25.4+/-2.2 optical density units in donor and 17.7+/-2.5 in DCM (*P<0.05). Total creatine was 87.5+/-4.2 nmol/mg protein in sham and 65.7+/-4.2 in MI rats (*P<0.05); creatine transporter protein was 139.0+/-8.7 optical density units in sham and 82.1+/-4.0 in MI (*P<0.05). CONCLUSIONS: Both in human and in experimental heart failure, creatine transporter protein content is reduced. This mechanism may contribute to the depletion of creatine compounds and thus to the reduced energy reserve in failing myocardium. This finding may have therapeutic implications, suggesting a search for treatment strategies targeted toward creatine transport.
Animals↗
Evidence against a role of physiological concentrations of estrogen in post-myocardial infarction remodeling.
OBJECTIVES: The purpose of this study was to examine whether endogenous estrogen deficiency induced by ovariectomy affects chronic left ventricular dysfunction post-myocardial infarction (MI). BACKGROUND: Epidemiologic findings suggest that mortality of postmenopausal women is increased after MI, but the underlying mechanisms are unknown. METHODS: Rats were either not ovariectomized (non-OVX), ovariectomized (OVX) or ovariectomized and treated with subcutaneous 17-beta-estradiol (E2) pellets (OVX + E2). Two weeks later, animals were sham-operated (Sham) or left coronary artery ligated (MI). Eight weeks later, in vivo echocardiographic and hemodynamic measurements were performed. Thereafter, hearts were isolated and perfused isovolumically. RESULTS: Mean infarct size was similar among the three MI groups. Ovariectomy decreased serum E2 levels (11 +/- 4 vs. 49 +/- 11 pg/ml in non-OVX, p < 0.01) and increased body weight. These changes were reversed by E2 replacement. The degree of cardiac hypertrophy was similar for all groups post-MI. Left ventricular diameters were increased post-MI (8.9 +/- 0.4 in non-OVX + MI vs. 6.7 +/- 0.2 mm in non-OVX + Sham hearts, p < 0.0001), but OVX or OVX + E2 replacement did not alter left ventricular diameters in post-MI and Sham hearts. Left ventricular fractional shortening was severely impaired post-MI (19 +/- 2% vs. 50 +/- 3 in non-OVX + Sham hearts, p < 0.0001) with no influence of hormonal status. Left ventricular end-diastolic pressure, measured in vivo, was increased in all MI groups without significant differences between groups. Pressure-volume curves, obtained in perfused hearts, demonstrated a right and downward shift with reduced maximum left ventricular developed pressure post-MI (75 +/- 6 vs. 108 +/- 3 mm Hg in non-OVX + Sham hearts, p < 0.001) and were also unaffected by either OVX or E2 replacement. CONCLUSIONS: Chronic endogenous estrogen deficiency does not have major effects on the development of cardiac hypertrophy, dysfunction and dilation post-MI.
Animals↗
Cardiac sympathetic activity as measured by myocardial 123-I-metaiodobenzylguanidine uptake and heart rate variability in idiopathic dilated cardiomyopathy.
In patients with idiopathic dilated cardiomyopathy (IDC) the increased sympathetic activity owing to chronic congestive heart failure leads to an imbalance of cardiac autonomic tone, as reflected by decreased heart rate variability (HRV). Iodine-123-metaiodobenzylguanidine (123-I-MIBG), which has the same affinity for sympathetic nerve endings as norepinephrine, can be used to assess the integrity and function of the cardiac sympathetic nervous system. The aim of the present study was to measure cardiac sympathetic activity by assessing 123-I-MIBG uptake compared with HRV in patients with IDC. In 12 patients with IDC and mild to moderate heart failure, myocardial MIBG uptake was calculated from the myocardial (M) to left ventricular cavity (C) voxel values density ratio and the 123-I activity in a blood sample as a reference (= M/C ratio) using a double radionuclide study with 123-I-MIBG and technetium-99m-MIBI. To investigate the relation between myocardial MIBG uptake and HRV in time domain, the linear regression between the M/C ratio, a new scintigraphic parameter, and the mean RR interval or the HRV triangular index, respectively, was determined. A significant correlation between the M/C ratio and mean RR interval (r = 0.52; p = 0.016) or M/C ratio and HRV triangular index (r = 0.76; p = 0.003), respectively, was found. Thus, the significant correlation between the M/C ratio and HRV indicate that they are both suitable noninvasive methods for evaluating cardiac sympathetic activity in patients with IDC and, furthermore, favor the view that there is evidence of a relation between HRV and the disorder of the cardiac presynaptic sympathetic nerve endings as demonstrated by a reduced M/C ratio.
3-Iodobenzylguanidine↗