Cardiac sympathetic activity estimated by 123I-MIBG myocardial imaging in patients with dilated cardiomyopathy after beta-blocker or angiotensin-converting enzyme inhibitor therapy.
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Impaired cardiac sympathetic activity can be evaluated by 123I-metaiodobenzylguanidine (MIBG) imaging. METHODS: We studied the significance of MIBG imaging for 24 patients (age 58+/-12 y) with dilated cardiomyopathy (DCM). We compared 12 patients (group A) treated with metoprolol (dose from 30-60 mg/d) with 12 patients treated with angiotensin-converting enzyme (ACE) inhibitors. Patients were studied before treatment, after 5 mo of treatment (only in group A) and after 1 y of treatment. Cardiac MIBG uptake was assessed as the heart-to-mediastinum activity ratio (H/M) and total defect score (TDS) from anterior planar and SPECT MIBG images, which were acquired in 4 h after tracer injection. New York Heart Association (NYHA) class and left ventricular ejection fraction (LVEF) calculated by echocardiography were also assessed. RESULTS: TDS decreased in both groups (in group A, from 30+/-7 through 23+/-9 to 18+/-10; P < 0.01, in group B, from 30+/-6 to 24+/-8; P < 0.01) and H/M was increased in both groups (in group A, from 1.87+/-0.31 through 2.03+/-0.28 to 2.14+/-0.29; P < 0.01, in group B, from 1.82+/-0.28 to 1.94+/-0.26; P < 0.05). But TDS and H/M were more improved in group A than in group B (P < 0.05). LVEF was significantly increased in only group A (from 38+/-6 through 43+/-8 to 49%+/-9%; P < 0.01). NYHA improved in both groups (in group A, from mean 2.5 through 2.1 to 1.8; P < 0.01, in group B, from mean 2.6 to 2.1; P < 0.05) but was more improved in group A than in group B (P < 0.05). CONCLUSION: Cardiac function, symptom and cardiac sympathetic activity evaluated by MIBG images improved after the beta-blocker therapy more than with the treatment that used ACE inhibitors. (+info)
Sympathetic nerve alterations assessed with 123I-MIBG in the failing human heart.
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Norepinephrine (NE) reuptake function is impaired in heart failure and this may participate in myocyte hyperstimulation by the neurotransmitter. This alteration can be assessed by 123I-metaiodobenzylguanidine (MIBG) scintigraphy. METHODS: To determine whether the impairment of neuronal NE reuptake was reversible after metoprolol therapy, we studied 18 patients (43+/-7 y) with idiopathic dilated cardiomyopathy who were stabilized at least for 3 mo with captopril and diuretics. Patients underwent, before and after 6 mo of therapy with metoprolol, measurements of radionuclide left ventricular ejection fraction (LVEF), maximal oxygen consumption and plasma NE concentration. The cardiac adrenergic innervation function was scintigraphically assessed with MIBG uptake and release measurements on the planar images obtained 20 min and 4 h after tracer injection. To evaluate whether metoprolol had a direct interaction with cardiac MIBG uptake and release, six normal subjects were studied before and after a 1-mo metoprolol intake. RESULTS: In controls, neither cardiac MIBG uptake and release nor circulating NE concentration changed after the 1-mo metoprolol intake. Conversely, after a 6-mo therapy with metoprolol, patients showed increased cardiac MIBG uptake (129%+/-10% versus 138%+/-17%; P = 0.009), unchanged cardiac MIBG release and decreased plasma NE concentration (0.930+/-412 versus 0.721+/-0.370 ng/mL; P = 0.02). In parallel, patients showed improved New York Heart Association class (2.44+/-0.51 versus 2.05+/-0.23; P = 0.004) and increased LVEF (20%+/-8% versus 27%+/-8%; P = 0.0005), whereas maximal oxygen uptake remained unchanged. CONCLUSION: Thus, a parallel improvement of myocardial NE reuptake and of hemodynamics was observed after a 6-mo metoprolol therapy, suggesting that such agents may be beneficial in heart failure by directly protecting the myocardium against excessive NE stimulation. (+info)
Effect of coronary occlusion on left ventricular function with and without collateral supply during beating heart coronary artery surgery.
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OBJECTIVE: To study the effects of coronary occlusion and collateral supply on left ventricular (LV) function during beating heart coronary artery surgery. DESIGN: Prospective intraoperative study, performed at baseline, during wall stabilisation, coronary artery occlusion, and 2 and 10 minutes after reperfusion. Transoesophageal M mode echocardiograms, simultaneous high fidelity LV pressure, and thermodilution cardiac output were measured. LV anterior wall thickening, thinning velocities, thickening fraction, regional work, and power production were derived. Asynchrony during the isovolumic periods was quantified as cycle efficiency. SETTING: Tertiary referral cardiac centre. PATIENTS: 14 patients with stable angina, mean (SD) age 62 (7) years, undergoing left anterior descending artery grafting using the "Octopus" device. RESULTS: Collaterals were absent in nine patients and present in five. Epicardial stabilisation did not affect LV function. Results are expressed as mean (SD). Coronary occlusion (15.6 (2) minutes) depressed anterior wall thickening (1.4 (0.6) v 2.6 (0.6) cm/s) and thinning velocities (1.4 (0.5) v 3.0 (0.6) cm/s), regional work (2.2 (0.8) v 4.6 (0.6) mJ/cm2), and power (21 (4) v 33 (5) mW/cm2) in patients without collaterals (p < 0.05 for all), but only wall thinning (3.5 (0.5) v 4.8 (0.5) cm/s, p < 0.05) in patients with collaterals. All returned to baseline within 10 minutes of reperfusion. Cycle efficiency and regional work were impaired at baseline and fell during occlusion, regardless of collaterals. Within 10 minutes of reperfusion both had increased above baseline. CONCLUSIONS: Coronary occlusion for up to 15 minutes during beating heart coronary artery surgery depressed standard measurements of systolic and diastolic anterior wall function in patients without collaterals, but only those of diastolic function in patients with collaterals. Regional synchrony decreased in both groups. All disturbances regressed within 10 minutes of reperfusion. (+info)
Peri-operative changes in echocardiographic measurements and plasma atrial and brain natriuretic peptide concentrations in 3 dogs with patent ductus arteriosus.
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Peri-operative changes in echocardiographic measurements and plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were investigated for 1 month in 3 dogs with patent ductus arteriosus (PDA). Post-operative left ventricular end-diastolic dimention and fractional shortening decreased in all cases. Pre-operatively increased plasma ANP concentrations reduced dramatically after the operation. Peri-operative changes in plasma BNP levels had slightly S-shaped curves in all cases. These observations suggest that post-operative responsiveness of ANP and cardiac function are rapid in comparison with cardiac morphological changes, and BNP has a different pathophysiological significance from ANP in dogs with PDA. (+info)
Hemodialysis with high-calcium dialysate impairs cardiac relaxation.
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BACKGROUND: During hemodialysis (HD), serum ionized calcium is directly related to the dialysate calcium concentration. We have recently shown an acute induction of hypercalcemia to impair left ventricular (LV) relaxation. In the current study we sought to establish whether changes in serum Ca++ also affect LV function during HD. METHODS: We echocardiographically examined the LV relaxation and systolic function of 12 patients with end-stage renal disease before and after three HD treatments with dialysate Ca++ concentrations of 1.25 mmol/liter (dCa++1.25), 1.5 mmol/liter (dCa++1.50), and 1.75 mmol/liter (dCa++1.75), respectively. Age- and sex-matched healthy controls were also examined echocardiographically. RESULTS: The LV posterior wall thickness and the interventricular septum thickness, and the LV end-diastolic dimension and the end-systolic dimensions were significantly greater in the patients when compared with the controls, and the LV fractional shortening, the ratio of peak early to peak late diastolic velocities (E/Amax), and the isovolumic relaxation time (IVRT) showed impairment of LV relaxation and systolic function in the patients. Serum ionized calcium increased significantly during the dCa++1.5 HD (1.24 +/- 0.10 vs. 1.34 +/- 0.06 mmol/liter, P = 0. 004) and dCa++1.75 HD (1.19 +/- 0.10 vs. 1.47 +/- 0.06 mmol/liter, P = 0.002), and plasma intact parathyroid hormone decreased significantly during the dCa++1.75 HD (medians 8.2 vs. 2.7 pmol/liter, P = 0.002). LV systolic function was not altered during any of the treatments. The changes in E/Amax and IVRT suggested impairment of relaxation during all sessions, but only during the dCa++1.75 HD was the impairment statistically significant (E/Amax 1. 153 +/- 0.437 vs. 0.943 +/- 0.352, P < 0.05; IVRT 147 +/- 29 vs. 175 +/- 50 msecond, P < 0.05). CONCLUSION: HD with high-calcium (dCa++1. 75 mmol/liter) dialysate impairs LV relaxation when compared with lower calcium dialysate (dCa++1.25 and dCa++1.5 mmol/liter) treatments. (+info)
Studies on structural changes of the carotid arteries and the heart in asymptomatic renal transplant recipients.
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BACKGROUND: The present study was designed to characterize early structural changes of large arteries in renal transplant recipients with no clinical evidence of cardiovascular disease and normal blood pressure values, and to analyse the relationship between arterial alterations and those of the heart. METHODS: Intima media thickness and atherosclerotic plaques of the carotid arteries as well as left ventricular geometry and function were examined in 35 asymtomatic renal transplant recipients and 29 age- and sex-matched healthy controls by high resolution B-mode ultrasound and by echocardiography. RESULTS: Intima-media thickness of the carotid arteries was significantly higher in renal transplant recipients (1.21+/-0.08 mm) than in healthy controls (0.74+/-0.04 mm) (P<0.001). Atherosclerotic plaques were found in the majority of renal transplant recipients (71% vs 14% in healthy controls, P<0.001). Left ventricular mass index was significantly increased in the group of renal transplant recipients (264+/-13 g, 146+/-7 g/m2) when compared with healthy controls (155+/-8 g, 83+/-4 g/m2) (P<0.001). Multiple regression analysis in renal transplant recipients showed that intima media thickness of the carotid arteries was significantly related to left ventricular mass index (P<0.02), but not to age, blood pressure, body mass index, serum creatinine, cholesterol and lipoprotein (a) levels. In the group of healthy controls, intima-media thickness of the carotid artery was related to age (P<0.002), but not to left ventricular mass index or the other independent variables. CONCLUSIONS: The present study documents pronounced intima-media thickening in asymptomatic renal transplant recipients. Atherosclerotic lesions are present in most renal transplant recipients with no clinical evidence of cardiovascular disease. We observed a parallelism between arterial wall thickening and left ventricular hypertrophy, although blood pressure levels were normal during haemodialysis therapy and after renal transplantation. (+info)
Regulation of myocardial blood flow by oxygen consumption is maintained in the failing heart during exercise.
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The hemodynamic abnormalities and neurohumoral activation that accompany congestive heart failure (CHF) might be expected to impair the increase in coronary blood flow that occurs during exercise. This study was performed to determine the effects of CHF on myocardial oxygen consumption and coronary blood flow during exercise. Coronary blood flow was measured in chronically instrumented dogs at rest, during 2 stages of graded treadmill exercise under control conditions (n=10), and after the development of CHF produced by 3 weeks of rapid ventricular pacing (n=9). In the normal dogs, coronary blood flow increased during exercise in proportion to the increase in the heart rate x the left ventricular systolic blood pressure product (RPP). After the development of CHF, resting myocardial blood flow was 25% lower than normal (P<0.05). Myocardial blood flow increased during the first stage of exercise, but then failed to increase further during the second stage of exercise despite an additional increase in the RPP. Myocardial oxygen consumption during exercise was significantly lower in animals with CHF and paralleled coronary flow. Despite the lower values for coronary blood flow in animals with CHF, there was no evidence for myocardial ischemia. Thus, even during the second level of exercise when coronary flow failed to increase, myocardial lactate consumption continued and coronary venous pH did not fall. In addition, the failure of coronary flow to increase as the exercise level was increased from stage 1 to stage 2 was not associated with a further increase in myocardial oxygen extraction. Thus, cardiac failure was associated with decreased myocardial oxygen consumption and failure of oxygen consumption to increase with an increase in the level of exercise. This abnormality did not appear to result from inadequate oxygen availability, but more likely represented a reduction of myocardial oxygen usage with a secondary decrease in metabolic coronary vasodilation. (+info)
Increased renal resistive index in patients with essential hypertension: a marker of target organ damage.
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BACKGROUND: Increased renal resistance detected by ultrasound (US) Doppler has been reported in severe essential hypertension (EH) and recently was shown to correlate with the degree of renal impairment in hypertensive patients with chronic renal failure. However, the pathophysiological significance of this finding is still controversial. METHODS: In a group of 211 untreated patients with EH, we evaluated renal resistive index (RI) by US Doppler of interlobar arteries and early signs of target organ damage (TOD). Albuminuria was measured as the albumin to creatinine ratio (ACR) in three non-consecutive first morning urine samples. Left ventricular mass was evaluated by M-B mode echocardiography, and carotid wall thickness (IMT) by high resolution US scan. RESULTS: RI was positively correlated with age (r=0.25, P=0.003) and systolic blood pressure (SBP) (r=0.2, P=0.02) and with signs of early TOD, namely ACR (r=0.22, P=0.01) and IMT (r=0.17, P<0.05), and inversely correlated with renal volume (r=-0.22, P=0.01) and diastolic blood pressure (r=-0.23, P=0.006). Multiple linear regression analysis demonstrated that age, gender, ACR and SBP independently influence RI and together account for approximately 20% of its variations (F=8.153, P<0.0001). When clinical data were analysed according to the degree of RI, the patients in the top quartile were found to be older (P<0.05) and with higher SBP (P<0.05) as well as early signs of TOD, namely increased ACR (P<0.002) and IMT (P<0.005 by ANOVA), despite similar body mass index, uric acid, fasting blood glucose, lipid profile and duration of hypertension. Furthermore, patients with higher RI showed a significantly higher prevalence of microalbuminuria (13 vs 12 vs 3 vs 33% chi2=11.72, P=0.008) and left ventricular hypertrophy (40 vs 43 vs 32 vs 60%, chi2=9.25, P<0.05). CONCLUSIONS: Increased RI is associated with early signs of TOD in EH and could be a marker of intrarenal atherosclerosis. (+info)