Biomedical subjects

Peter Kies

Publications and source records attributed to Peter Kies.

6 recordsLinked to original sources

PubMed2007

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: validation of an elastic surface model approach in comparison to cardiac magnetic resonance imaging, 4D-MSPECT and QGS.

PURPOSE: The segmentation algorithm ESM based on an elastic surface model was validated for the assessment of left ventricular volumes and ejection fraction from ECG-gated myocardial perfusion SPECT. Additionally, it was compared with the commercially available quantification packages 4D-MSPECT and QGS. Cardiac MRI was used as the reference method. METHODS: SPECT and MRI were performed on 70 consecutive patients with suspected or proven coronary artery disease. End-diastolic (EDV) and end-systolic (ESV) volumes and left ventricular ejection fraction (LVEF) were derived from SPECT studies by using the segmentation algorithms ESM, 4D-MSPECT and QGS and from cardiac MRI. RESULTS: ESM-derived values for EDV and ESV correlated well with those from cardiac MRI (correlation coefficients R=0.90 and R=0.95, respectively), as did the measurements for LVEF (R=0.86). Both EDV and ESV were slightly overestimated for larger ventricles but not for smaller ventricles; LVEF was slightly overestimated irrespective of ventricle size. The above correlation coefficients are comparable to those for the 4D-MSPECT and QGS segmentation algorithms. However, results obtained with the three segmentation algorithms are not interchangeable. CONCLUSION: The ESM algorithm can be used to assess EDV, ESV and LVEF from gated perfusion SPECT images. Overall, the performance was similar to that of 4D-MSPECT and QGS when compared with cardiac MRI. Results obtained with the three tested segmentation methods are not interchangeable, so that the same algorithm should be used for follow-up studies and control subjects.

Adult↗

PubMed2007

Molecular cardiovascular imaging using scintigraphic methods.

Molecular cardiovascular imaging plays an increasingly important role both in basic research and in clinical diagnosis. Scintigraphic methods have long been used to study pathophysiological changes on a cellular and molecular level, and they are likely to remain important molecular imaging modalities in the foreseeable future. This article provides an overview over current developments in cardiovascular molecular imaging using scintigraphic methods. The focus lies on imaging of cardiac innervation, plaque instability, hypoxia and angiogenesis, gene expression and stem and progenitor cell migration and proliferation.

Animals↗

PubMed2006

Impact of sympathetic innervation on recurrent life-threatening arrhythmias in the follow-up of patients with idiopathic ventricular fibrillation.

PURPOSE: Idiopathic ventricular fibrillation (IVF) is defined as VF in the absence of any identifiable structural or functional cardiac disease. The underlying pathophysiological mechanisms are unknown. This study was performed to investigate the potential impact of sympathetic dysfunction, assessed by (123)I-meta-iodo-benzylguanidine scintigraphy ((123)I-MIBG SPECT), on the long-term prognosis of patients with IVF. METHODS: (123)I-MIBG SPECT was performed in 20 patients (mean age 37+/-13 years) with IVF. Mean follow-up of patients after study entry was 7.2+/-1.5 years (range 4.9-10.5 years). Ten patients (five men, five women; mean age 43+/-12 years; p=NS versus study group) with medullary carcinoma of the thyroid gland served as an age-matched control group. RESULTS: Abnormal (123)I-MIBG uptake was observed in 13 patients (65%). During follow-up, 18 episodes of VF/fast polymorphic ventricular tachycardias occurred in four IVF patients with abnormal (123)I-MIBG uptake whereas only two episodes of monomorphic ventricular tachycardia (and no VF) occurred in a single IVF patient with normal (123)I-MIBG uptake. CONCLUSION: Impairment of sympathetic innervation may indicate a higher risk of future recurrent episodes of life-threatening ventricular tachyarrhythmias in patients with IVF. Studies in larger cohorts are required to validate the significance of (123)I-MIBG SPECT during the long-term follow-up of these patients.

3-Iodobenzylguanidine↗

PubMed2004

Abnormal myocardial presynaptic norepinephrine recycling in patients with Brugada syndrome.

BACKGROUND: Life-threatening ventricular tachyarrhythmias can occur in young patients without structural heart disease (idiopathic forms). In many patients, these are typically triggered by an increased sympathetic tone, eg, by physical or mental stress. In contrast, in Brugada syndrome, ventricular tachyarrhythmias more often occur during rest or sleep when the vagal tone is predominant. Furthermore, adrenergic agonists can reduce the level of ST-segment elevation, whereas it is increased by parasympathetic agonists or adrenergic antagonists. The aim of this study was to investigate presynaptic and postsynaptic myocardial sympathetic function in patients with Brugada syndrome. METHODS AND RESULTS: Nine patients with Brugada syndrome (6 male, 3 female; age, 41+/-13 years) were enrolled in this study. The cardiac autonomic nervous system was assessed noninvasively, quantifying myocardial presynaptic and postsynaptic sympathetic function by means of positron emission tomography with the norepinephrine analogue 11C-Hydroxyephedrine (11C-HED) and the nonselective beta-blocker 11C-CGP 12177 (11C-CGP). Presynaptic sympathetic norepinephrine recycling, assessed by 11C-HED, was globally increased in patients with Brugada syndrome compared with a group of age-matched healthy control subjects (92.9+/-16.2 mL/g versus 69.1+/-14.2 mL/g; P<0.05), whereas postsynaptic beta-adrenoceptor density, assessed by 11C-CGP, was similar in patients and control subjects (10.4+/-6.7 pmol/g versus 10.2+/-2.9 pmol/g; P=NS). CONCLUSIONS: The present study on autonomic innervation in Brugada syndrome describes an enhanced presynaptic norepinephrine recycling with preserved beta-adrenoceptor density, further supporting the hypothesis of an autonomic dysfunction in Brugada syndrome. This is a further step toward the understanding of the pathophysiology of the disease with potential future impact on therapeutic strategies.

Adult↗

PubMed2004

Functional changes after partial left ventriculectomy and mitral valve repair assessed by gated perfusion SPECT.

UNLABELLED: A myocardial remodeling in dilated cardiomyopathy (DCM) after partial left ventriculectomy (PLV) has been previously discussed. The aim of this study was to investigate the functional changes in the follow-up of patients with DCM undergoing PLV using electrocardiographically triggered perfusion SPECT (gated SPECT). METHODS: Twelve DCM patients (10 men, 2 women; 56 +/- 9 y [mean +/- SD]), after successful PLV and mitral valve repair (PLV-MVR), were monitored by gated SPECT and echocardiography. Gated SPECT quantified end-diastolic volumes (EDV), end-systolic volumes (ESV), myocardial and scar volumes, as well as ejection fraction (EF) preoperatively, early (38 +/- 28 d), and late (296 +/- 130 d) after PLV-MVR. RESULTS: EDV and ESV showed an immediate reduction after PLV-MVR (EDV from 542 +/- 90 mL to 350 +/- 81 mL, P < 0.001; ESV from 452 +/- 91 mL to 254 +/- 79 mL, P < 0.001) with no significant change in the late follow-up (EDV late, 316 +/- 63 mL; ESV late, 207 +/- 63 mL; both P = not significant vs. early follow-up). PLV-MVR immediately improved EF (preoperative, 16.8% +/- 5.5%; early, 28.8% +/- 7.6%; P = 0.003) with no significant change in the late follow-up (36.0% +/- 9.4%; P = not significant vs. early follow-up). CONCLUSION: In this highly selected DCM patient group, gated perfusion SPECT assessed early responses in volumes and EF after PLV-MVR. However, although statistically nonsignificant in the small patient group, ESV and EDV were further decreased, whereas EF improved toward 1 y, coinciding with the improvement of clinical symptoms (New York Heart Association), potentially indicating a functional remodeling after PLV-MVR. Further studies in larger patient cohorts and longer follow-up are warranted.

Adult↗

PubMed2002

Cardiac autonomic dysfunction in Brugada syndrome.

BACKGROUND: Patients with Brugada syndrome present with characteristic ECG abnormalities (atypical right bundle-branch block and ST-segment elevation) and life-threatening ventricular tachyarrhythmias despite structurally normal hearts. Involvement of the autonomic nervous system is suggested by the occurrence of ventricular tachyarrhythmias and sudden death at rest or during sleep and by changes of typical ECG signs under pharmacological modulation of the myocardial autonomic tone. METHODS AND RESULTS: This study investigated the presynaptic cardiac neuronal reuptake of norepinephrine (uptake 1) in 17 patients with Brugada syndrome and 10 age-matched control subjects with the use of the norepinephrine analogue [123I]m-iodobenzylguanidine (123I-MIBG), single-photon emission CT (SPECT), and quantitative 33-segment bull's-eye analysis. Regionally reduced 123I-MIBG uptake was present in 8 (47%) of 17 patients with Brugada syndrome but in none of the control subjects. Quantitative analysis showed segmental reduction of 123I-MIBG uptake in the inferior and septal left ventricular wall in patients with Brugada syndrome compared with control subjects (P<0.05). No correlation was found between the findings of 123I-MIBG-SPECT and clinical characteristics of the study patients. CONCLUSIONS: The present study demonstrated an abnormal 123I-MIBG uptake in patients with Brugada syndrome, indicating presynaptic sympathetic dysfunction of the heart. These findings may have potential impact on the pathophysiology and arrhythmogenesis in patients with Brugada syndrome. Future quantitative investigations of the presynaptic and postsynaptic sympathetic and parasympathetic branches of the cardiac autonomic nervous system may clarify whether these observations represent a primary adrenergic dysfunction or an imbalance between sympathetic and parasympathetic innervation of the heart.

3-Iodobenzylguanidine↗