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Biomedical subjects

Paolo G Camici

Publications and source records attributed to Paolo G Camici.

At least 19 recordsLinked to original sources
PubMed2006

Myocardial glucose transport and utilization in patients with type 2 diabetes mellitus, left ventricular dysfunction, and coronary artery disease.

OBJECTIVES: This research was designed to assess the effect of type 2 diabetes mellitus (T2DM) on myocardial glucose utilization in patients with heart failure secondary to coronary artery disease. BACKGROUND: Patients with T2DM and coronary artery disease have an increased morbidity and mortality compared with patients with coronary artery disease without diabetes that may relate to a reduction in the ability of the myocardium to utilize glucose. METHODS: Myocardial blood flow and glucose utilization were assessed during a hyperinsulinemic clamp by 18F-flurodeoxyglucose and positron emission tomography in 54 patients (19 with T2DM) with multivessel coronary artery disease and heart failure. In a subgroup of 18 patients, myocardial biopsies were obtained during coronary bypass surgery to assess glucose transporter (GLUT4) distribution and protein concentration, and compared with myocardium from transplant donor hearts. RESULTS: Myocardial blood flow was similar in patients without diabetes and those with T2DM. Myocardial glucose utilization was lower in patients with T2DM (0.34 +/- 0.16 vs. 0.47 +/- 0.24 micromol x min(-1) x g(-1), p = 0.0002) despite comparable plasma insulin concentrations and a higher blood glucose concentration. Extraction of glucose by the myocardium was reduced in patients with T2DM (7.1 +/- 3.1% vs. 13.5 +/- 5.2%, p < 0.01). Myocardial GLUT4 protein was similar in patients with and without T2DM (p = 0.75). CONCLUSIONS: Patients with coronary artery disease and heart failure exhibit myocardial insulin resistance, and this is greater in those with T2DM. This may limit the ability of the myocardium in patients with T2DM to withstand ischemia and may contribute to the increased cardiovascular morbidity and mortality in such patients.

Aged↗
PubMed2006

Basal and hyperaemic myocardial blood flow in regionally denervated canine hearts: an in vivo study with positron emission tomography.

PURPOSE: Positron emission tomography (PET) studies in patients with diabetic autonomic neuropathy (DAN) have demonstrated the impact of this disease on cardiac sympathetic innervation and myocardial blood flow (MBF). To investigate the effects of selective partial sympathetic denervation of the left ventricle (LV) on baseline and hyperaemic MBF, we measured myocardial presynaptic catecholamine re-uptake (uptake-1), beta-adrenoceptor (beta-AR) density and MBF non-invasively by means of PET in a canine model of regional sympathetic denervation. METHODS: In 11 anaesthetised dogs, the sympathetic nerves of the free wall and septum of the LV were removed by means of dissection and phenol painting. Three weeks later, the animals were studied with PET. MBF was measured at baseline and following i.v. adenosine (140 microg kg(-1) min(-1)) and dobutamine (20 microg kg(-1) min(-1)) using(15)O-labelled water. Sympathetic denervation was confirmed by an 80+/-12% decrease in the volume of distribution (V(d)) of [(11)C]hydroxyephedrine (HED) compared with innervated regions. Myocardial beta-AR density was measured using [(11)C]CGP12177. RESULTS: Innervated and denervated regions showed no differences in MBF at baseline and during adenosine or dobutamine. [(11)C]HED V(d)was inversely correlated with MBF in both regions at baseline, and the correlation was lost during hyperaemia in denervated regions. However, for any given value of MBF, [(11)C]HED V(d)was significantly lower in the denervated regions. beta-AR density was comparable in denervated and innervated regions (17.9+/-4.2 vs 18.4+/-3.3 pmol g(-1); p=NS). CONCLUSION: In this experimental model, selective, regional sympathetic denervation of the LV, which results in a profound reduction in [(11)C]HED V(d), did not affect baseline or hyperaemic MBF. In addition, we demonstrated that, under baseline conditions, there was a significant inverse correlation between [(11)C]HED V(d)and MBF in both denervated and innervated regions.

Animals↗
PubMed2006

Relevance of coronary microvascular flow impairment to long-term remodeling and systolic dysfunction in hypertrophic cardiomyopathy.

OBJECTIVES: This study sought to evaluate whether the entity of microvascular dysfunction, assessed by positron emission tomography (PET), predicts the long-term development of left ventricular (LV) remodeling and systolic dysfunction in hypertrophic cardiomyopathy (HCM). BACKGROUND: A subgroup of patients with HCM developed LV dilation and systolic impairment. A causal role of coronary microvascular dysfunction has been suggested as the underlying pathophysiological mechanism. METHODS: Fifty-one patients (New York Heart Association functional class I to II) were followed up for 8.1 +/- 2.1 years after measurement of resting and dipyridamole (Dip) myocardial blood flow (MBF). Left ventricular systolic dysfunction was defined as an ejection fraction (LVEF) <50%. RESULTS: The Dip-MBF was blunted in HCM patients compared with a group of healthy control patients (1.50 +/- 0.69 ml/min/g vs. 2.71 +/- 0.94 ml/min/g; p < 0.001). At final evaluation, 11 patients (22%) had an LVEF <50%; in most (n = 7), systolic dysfunction was associated with a significant increase in LV cavity dimensions (>5 mm) during follow-up. These 11 patients showed lower Dip-MBF than the 40 with preserved LV function (1.04 +/- 0.38 ml/min/g vs. 1.63 +/- 0.71 ml/min/g, respectively; p = 0.001); Dip-MBF was particularly blunted in five patients with clinical progression to severe heart failure symptoms or death (Dip-MBF 0.89 +/- 0.15 ml/min/g). At multivariate analysis, the two independent predictors of systolic dysfunction were Dip-MBF in the lowest tertile (<1.1 ml/min/g; relative hazard, 7.5; p = 0.038) and an end-diastolic LV dimension in the highest tertile (>45 mm; relative hazard, 12.3; p = 0.031). CONCLUSIONS: Severe microvascular dysfunction is a potent long-term predictor of adverse LV remodeling and systolic dysfunction in HCM. Our findings indicate microvascular dysfunction as a potential target for prevention of disease progression and heart failure in HCM.

Aged↗
PubMed2006

Respiratory gating of cardiac PET data in list-mode acquisition.

PURPOSE: Respiratory motion has been identified as a source of artefacts in most medical imaging modalities. This paper reports on respiratory gating as a means to eliminate motion-related inaccuracies in PET imaging. METHODS: Respiratory gating was implemented in list mode with physiological signal recorded every millisecond together with the PET data. Respiration was monitored with an inductive respiration monitor using an elasticised belt around the patient's chest. Simultaneous ECG gating can be maintained independently by encoding ECG trigger signal into the list-mode data. Respiratory gating is performed in an off-line workstation with gating parameters defined retrospectively. The technique was applied on a preliminary set of patient data with C(15)O. RESULTS: Motion was visually observed in the cine displays of the sagittal and coronal views of the reconstructed respiratory gated images. Significant changes in the cranial-caudal position of the heart could be observed. The centroid of the cardiac blood pool showed an excursion of 4.5-16.5 mm (mean 8.5+/-4.8 mm) in the cranial-caudal direction, with more limited excursion of 1.1-7.0 mm (mean 2.5+/-2.2 mm) in the horizontal direction and 1.3-3.7 mm (mean 2.4+/-0.9 mm) in the vertical direction. CONCLUSION: These preliminary data show that the extent of motion involved in respiration is comparable to myocardial wall thickness, and respiratory gating may be considered in order to reduce this effect in the reconstructed images.

Artifacts↗
PubMed2006

Occurrence of regional left ventricular dysfunction in patients undergoing standard and biofeedback dialysis.

BACKGROUND: Cardiac failure and cardiovascular death are extremely prevalent in dialysis patients. Recurrent subclinical myocardial ischemia is important in the genesis of heart failure in nondialysis patients. We examined whether this phenomenon occurs in response to the stress of hemodialysis (HD). METHODS: Eight patients prone to intradialytic hypotension were recruited for a randomized crossover study to compare the development of left ventricular regional wall motion abnormalities during standard (HD) and biofeedback dialysis. Patients underwent serial echocardiography with quantitative analysis to assess ejection fraction and regional left ventricular systolic function during both types of dialysis. Blood pressure and hemodynamic variables also were measured by using continuous pulse wave analysis. RESULTS: Forty-two new regional wall motion abnormalities developed in all 8 patients during HD compared with 23 regional wall motion abnormalities that developed in 7 patients during biofeedback dialysis (odds ratio, 1.8; 95% confidence interval, 1.1 to 3.0). The majority of regional wall motion abnormalities showed improvement in function by 30 minutes postdialysis. Overall mean regional function was significantly more impaired during HD (P = 0.022). At peak stress, ejection fraction (measured by percentage of change from baseline) was significantly lower during HD (P = 0.043). Blood pressure was higher during biofeedback dialysis, with significantly fewer episodes of hypotension (odds ratio, 2.0; 95% confidence interval, 1.01 to 4.4). Significantly smaller decreases in stroke volume and cardiac output and a greater increment in pulse rate were observed during biofeedback dialysis. CONCLUSION: This study shows that reversible left ventricular wall motion abnormalities develop during dialysis with ultrafiltration. We also show that this phenomenon can be ameliorated by the improved hemodynamic stability of biofeedback dialysis and therefore is a potential target for intervention.

Aged↗
PubMed2006

Effects of long-term oral dipyridamole treatment on coronary microcirculatory function in patients with chronic stable angina: A substudy of the persantine in stable angina (PISA) study.

AIMS: A meta-analysis of 13 randomized placebo-controlled trials demonstrated a benefit for dipyridamole therapy, particularly with longer duration of treatment. Although the mechanism of this effect is not well understood, dipyridamole increases endogenous tissue adenosine, which may have a beneficial effect on myocardial perfusion. Therefore, we measured the effects of dipyridamole on myocardial blood flow (MBF) and coronary flow reserve (CFR) by using positron emission tomography and H2O in patients with coronary artery disease. METHODS: Forty-four patients with angiographically documented coronary artery disease were double-blind randomized to either oral dipyridamole [200 milligrams (mg) twice daily (bd)] or placebo as add-on to conventional antianginal treatment for 24 weeks. MBF was measured at rest and during dobutamine stress at baseline and study completion for the region subtended by the most severe coronary artery stenosis (Isc) and remote myocardium subtended by arteries with minimal or no disease (Rem). CFR was calculated as MBF-peak/MBF-rest. RESULTS: Thirty-five patients completed the study. Isc MBF-rest decreased in patients receiving dipyridamole (0.10 mL/minute/g; P = 0.03) and increased in the placebo group (0.16 mL/minute/g; P = 0.01) during the 24-week study. No significant change in MBF-peak was demonstrated in either group. Consequently, Isc-CFR increased significantly in patients receiving dipyridamole (1.65 +/- 0.47 vs 1.83 +/- 0.67; P < 0.05). By contrast, Isc-CFR decreased significantly in those receiving placebo (1.74 +/- 0.44 versus 1.38 +/- 0.46; P < 0.03). No change was seen in Rem-CFR territories. CONCLUSIONS: At the end of treatment, a reduction in baseline MBF but no significant changes in hyperemic MBF were observed in ischemic myocardial territories, and therefore the significance of the observed improvement in CFR remains unclear.

Administration, Oral↗
PubMed2006

Quantification of subendocardial and subepicardial blood flow using 15O-labeled water and PET: experimental validation.

UNLABELLED: The purpose of this study was to assess the feasibility and accuracy of quantifying subendocardial and subepicardial myocardial blood flow (MBF) and the relative coronary flow reserves (CFR) using (15)O-labeled water (H(2)(15)O) and 3-dimensional-only PET. METHODS: Eight pigs were scanned with H(2)(15)O and (15)O-labeled carbon monoxide (C(15)O) after partially occluding the circumflex (n = 3) or the left anterior descending (n = 5) coronary artery, both at rest and during hyperemia induced by intravenous dipyridamole. Radioactive microspheres were injected during each of the H(2)(15)O scans. RESULTS: In a total of 256 paired measurements of MBF, ranging from 0.30 to 4.46 mL.g(-1).min(-1), microsphere and PET MBF were fairly well correlated. The mean difference between the 2 methods was -0.01 +/- 0.52 mL.g(-1).min(-1) with 95% of the differences lying between the limits of agreement of -1.02 and 1.01 mL.g(-1).min(-1). CFR was significantly reduced (P < 0.05) in the ischemic subendocardium (PET = 1.12 +/- 0.45; microspheres = 1.09 +/- 0.50; P = 0.86) and subepicardium (PET = 1.2 +/- 0.35; microspheres = 1.32 +/- 0.5; P = 0.39) in comparison with remote subendocardium (PET = 1.7 +/- 0.62; microspheres = 1.64 +/- 0.61; P = 0.68) and subepicardium (PET = 1.79 +/- 0.73; microspheres = 2.19 +/- 0.86; P = 0.06). CONCLUSION: Dynamic measurements using H(2)(15)O and a 3-dimensional-only PET tomograph allow regional estimates of the transmural distribution of MBF over a wide flow range, although transmural flow differences were underestimated because of the partial-volume effect. PET subendocardial and subepicardial CFR were in good agreement with the microsphere values.

Algorithms↗
PubMed2005

Guidelines for percutaneous coronary interventions. The Task Force for Percutaneous Coronary Interventions of the European Society of Cardiology.

In patients with stable CAD, PCI can be considered a valuable initial mode of revascularization in all patients with objective large ischaemia in the presence of almost every lesion subset, with only one exception: chronic total occlusions that cannot be crossed. In early studies, there was a small survival advantage with CABG surgery compared with PCI without stenting. The addition of stents and newer adjunctive medications improved the outcome for PCI. The decision to recommend PCI or CABG surgery will be guided by technical improvements in cardiology or surgery, local expertise, and patients' preference. However, until proved otherwise, PCI should be used only with reservation in diabetics with multi-vessel disease and in patients with unprotected left main stenosis. The use of drug-eluting stents might change this situation. Patients presenting with NSTE-ACS (UA or NSTEMI) have to be stratified first for their risk of acute thrombotic complications. A clear benefit from early angiography (<48 h) and, when needed, PCI or CABG surgery has been reported only in the high-risk groups. Deferral of intervention does not improve outcome. Routine stenting is recommended on the basis of the predictability of the result and its immediate safety. In patients with STEMI, primary PCI should be the treatment of choice in patients presenting in a hospital with PCI facility and an experienced team. Patients with contra-indications to thrombolysis should be immediately transferred for primary PCI, because this might be their only chance for quickly opening the coronary artery. In cardiogenic shock, emergency PCI for complete revascularization may be life-saving and should be considered at an early stage. Compared with thrombolysis, randomized trials that transferred the patients for primary PCI to a 'heart attack centre' observed a better clinical outcome, despite transport times leading to a significantly longer delay between randomization and start of the treatment. The superiority of primary PCI over thrombolysis seems to be especially clinically relevant for the time interval between 3 and 12 h after onset of chest pain or other symptoms on the basis of its superior preservation of myocardium. Furthermore, with increasing time to presentation, major-adverse-cardiac-event rates increase after thrombolysis, but appear to remain relatively stable after primary PCI. Within the first 3 h after onset of chest pain or other symptoms, both reperfusion strategies seem equally effective in reducing infarct size and mortality. Therefore, thrombolysis is still a viable alternative to primary PCI, if it can be delivered within 3 h after onset of chest pain or other symptoms. Primary PCI compared with thrombolysis significantly reduced stroke. Overall, we prefer primary PCI over thrombolysis in the first 3 h of chest pain to prevent stroke, and in patients presenting 3-12 h after the onset of chest pain, to salvage myocardium and also to prevent stroke. At the moment, there is no evidence to recommend facilitated PCI. Rescue PCI is recommended, if thrombolysis failed within 45-60 min after starting the administration. After successful thrombolysis, the use of routine coronary angiography within 24 h and PCI, if applicable, is recommended even in asymptomatic patients without demonstrable ischaemia to improve patients' outcome. If a PCI centre is not available within 24 h, patients who have received successful thrombolysis with evidence of spontaneous or inducible ischaemia before discharge should be referred to coronary angiography and revascularized accordingly--independent of 'maximal' medical therapy.

Angioplasty, Balloon, Coronary↗
PubMed2005

Assessment of the long-term reproducibility of baseline and dobutamine-induced myocardial blood flow in patients with stable coronary artery disease.

UNLABELLED: Although physical exercise is the preferred stimulus for cardiac stress testing, pharmacologic agents are useful in patients who are unable to exercise. Previous studies have demonstrated short-term repeatability of exercise and adenosine stress, but little data exist regarding dobutamine (Dob) stress or the long-term reproducibility of pharmacologic stressors in coronary artery disease (CAD) patients. PET allows accurate, noninvasive quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR). The aim of the study was to investigate the long-term reproducibility of Dob stress on MBF and CFR in CAD patients using PET. METHODS: Fifteen patients with chronic stable angina and angiographically proven CAD (>70% stenosis in at least 1 major coronary artery) underwent PET with (15)O-labeled water and Dob stress at baseline (time [t] = 0) and after 24 wk (t = 24). MBF at rest and MBF during Dob stress were calculated for the whole left ventricle, the region subtended by the most severe coronary artery stenosis (Isc), and remote myocardium subtended by arteries with minimal or no disease (Rem). Reproducibility was assessed using the Bland-Altman (BA) repeatability coefficient and was also expressed as a percentage of the mean value of the 2 measurements (%BA). RESULTS: Dob dose (30 +/- 11 vs. 031 +/- 11 microg/kg/min; P = not significant [ns]) and peak Dob rate.pressure product (20,738 +/- 3,947 vs. 20,047 +/- 3,455 mm Hg x beats/min; P = ns) were comparable at t = 0 and t = 24. There was no significant difference in resting or Dob MBF (mL/min/g) between t = 0 and t = 24 for the whole left ventricle (1.03 +/- 0.19 vs. 1.10 +/- 0.20 and 2.02 +/- 0.44 vs. 2.09 +/- 0.57; P = ns for both), Isc (1.05 +/- 0.24 vs. 1.10 +/- 0.26 and 1.79 +/- 0.53 vs. 1.84 +/- 0.62; P = ns for both), or Rem (1.03 +/- 0.23 vs. 1.10 +/- 0.26 and 2.27 +/- 0.63 vs. 2.26 +/- 0.63; P = ns for both) territories. Global (1.98 +/- 0.40 vs. 1.90 +/- 0.46; P = ns) and regional CFR (Isc: 1.65 +/- 0.40 vs. 1.67 +/- 0.47, and Rem: 2.25 +/- 0.57 vs. 2.06 +/- 0.51; P = ns) were reproducible. The BA repeatability coefficients (and %BA) for MBF in ischemic and remote territories were 0.3 (28%) and 0.26 (24%) at rest and 0.49 (27%) and 0.58 (26%) during Dob stress. CONCLUSION: In patients with clinically stable CAD, Dob induces reproducible changes in both global and regional MBF and CFR over a time interval of 24 wk. The reproducibility of MBF and CFR with Dob was comparable with the short-term repeatability reported for adenosine and physical exercise in healthy subjects.

Angina, Unstable↗