Assessment of coronary function in children with a history of Kawasaki disease using (15)O-water positron emission tomography

13N-Ammonia myocardial blood flow quantitation in patient with aneurismal coronary artery disease

Aneurysmal coronary artery disease includes coronary artery aneurysms and ectasia; this condition has been associated with poor long-term outcomes. Few studies have explored myocardial blood flow 13N-ammonia PET/CT MPI added value. We present a 45-year-old man who came to the emergency department with chest pain. After a physical examination and laboratory studies, he was diagnosed with very high-risk unstable angina and referred to the catheterization laboratory. Coronary angiography showed the culprit lesion in the LCx and was treated by angioplasty and stent. LAD was found with coronary artery ectasia (TIMI 2 flow grade) and the RCA with aneurysmal disease in the proximal and middle segments (TIMI 3 flow grade). Medical treatment was decided for these findings and the patient was discharged. Two weeks later, we performed a 13N-ammonia PET/CT MPI founding apical, inferior, and inferoseptal severe ischemia, and reduced hyperemic coronary blood flow and coronary flow reserve in the RCA territory. Flow was normal in the LAD territory. Although coronary angiography remains the gold standard for evaluating these coronary abnormalities, it does not show the physiological compromise. Therefore 13N-ammonia PET/CT MPI should be performed as a complementary noninvasive imaging approach.

Peripheral Coronary Artery Circulatory Dysfunction in Remote Stage Kawasaki Disease Patients Detected by Adenosine Stress 13N-Ammonia Myocardial Perfusion Positron Emission Tomography

Coronary peripheral circulatory disturbances in the remote stage of Kawasaki disease have been reported. In this study, of the 50 patients in the remote stage of Kawasaki disease who underwent coronary perfusion evaluation using adenosine-loaded ¹³N-ammonia positron emission tomography, 28 patients who did not have stenosis of ≥75% in the left coronary artery underwent an evaluation for myocardial flow reserve (MFR) of the left anterior descending artery (LAD) and left circumflex artery (LCx). Clinical findings were compared between patients with normal (≥2.0) and abnormal (<2.0) MFRs. In the group with an abnormal MFR in the LAD, the responsiveness of the coronary vascular resistance to adenosine stress decreased even in the LCx (3.50 ± 1.23 vs. 2.39 ± 0.25, p = 0.0100). In the group with an abnormal MFR in the LCx, the responsiveness of the coronary vascular resistance in the LAD also decreased (3.27 ± 1.39 vs. 2.03 ± 0.25, p = 0.0105), and the age of onset of Kawasaki disease tended to be younger in the group with abnormal MFR in the LAD and LCx. We found that the peripheral coronary circulation was extensively impaired in the remote stage of Kawasaki disease, suggesting that an early onset of Kawasaki disease may affect the peripheral coronary circulation in later years.

Imaging the delayed complications of childhood Kawasaki disease

This review will discuss the long-term complications of Kawasaki disease with a particular focus on imaging surveillance of the coronary arteries in adolescence and adult life. The relative advantages and disadvantages of each modality will be illustrated with practical examples, demonstrating that, in many cases, a multimodality imaging strategy may be required.

Pediatric Cardiac PET/CT Imaging

With the routine availability of PET/CT imaging for oncologic purposes, there has been renewed interest in and acceptance of cardiac and neurologic applications of PET/CT. As our understanding of the pathophysiology underlying various pediatric heart diseases has improved, there has been a parallel advance in imaging modalities. Cardiac MR imaging and cardiac PET continue to improve in the pediatric domain. Molecular imaging holds promise to provide a more robust assessment of the cardiac pathophysiology in a 1-stop setting with less radiation exposure to the patient, an important consideration for the pediatric patient population.

Presentation of missed childhood Kawasaki disease in adults: Experience from a tertiary care center in north India

AIM

Kawasaki disease (KD) is the most common cause of acquired heart disease in children in Japan, North America and Europe. Undiagnosed and untreated KD can have clinically significant consequences later in life. The clinical spectrum of missed childhood KD is frequently being recognized during adulthood. We report four adult cases of acute coronary events, in which coronary angiography was suggestive of sequelae of KD.

METHODS

Four adults who presented with acute coronary events, had coronary angiography for evaluation. Indoor-admission files were analyzed for the clinical details of individual cases.

RESULTS

Two cases were below 40 years of age. None of the patients had any known conventional risk factors for atherosclerosis. Case 4 had a clinical history of childhood KD. Coronary angiography revealed ectasia of multiple coronary arteries and stenosis in distal segments in the first three cases and large thrombosed aneurysm with calcified walls in the fourth case.

CONCLUSION

We hereby report four adult cases with acute coronary events, who had markedly dilated coronary artery segments suggestive of possible sequelae of childhood KD.

Diagnosis, Treatment, and Long-Term Management of Kawasaki Disease: A Scientific Statement for Health Professionals From the American Heart Association

BACKGROUND

Kawasaki disease is an acute vasculitis of childhood that leads to coronary artery aneurysms in ≈25% of untreated cases. It has been reported worldwide and is the leading cause of acquired heart disease in children in developed countries.

METHODS AND RESULTS

To revise the previous American Heart Association guidelines, a multidisciplinary writing group of experts was convened to review and appraise available evidence and practice-based opinion, as well as to provide updated recommendations for diagnosis, treatment of the acute illness, and long-term management. Although the cause remains unknown, discussion sections highlight new insights into the epidemiology, genetics, pathogenesis, pathology, natural history, and long-term outcomes. Prompt diagnosis is essential, and an updated algorithm defines supplemental information to be used to assist the diagnosis when classic clinical criteria are incomplete. Although intravenous immune globulin is the mainstay of initial treatment, the role for additional primary therapy in selected patients is discussed. Approximately 10% to 20% of patients do not respond to initial intravenous immune globulin, and recommendations for additional therapies are provided. Careful initial management of evolving coronary artery abnormalities is essential, necessitating an increased frequency of assessments and escalation of thromboprophylaxis. Risk stratification for long-term management is based primarily on maximal coronary artery luminal dimensions, normalized as Z scores, and is calibrated to both past and current involvement. Patients with aneurysms require life-long and uninterrupted cardiology follow-up.

CONCLUSIONS

These recommendations provide updated and best evidence-based guidance to healthcare providers who diagnose and manage Kawasaki disease, but clinical decision making should be individualized to specific patient circumstances.

Higher CHADS2 score is associated with impaired coronary flow reserve: A study using phase contrast cine magnetic resonance imaging

BACKGROUND

The presence of coronary microvascular dysfunction (CMD) is an important prognostic marker for coronary artery disease (CAD) patients. The purpose of this study was to investigate whether the CHADS2 score is associated with CMD evaluated by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One hundred forty three patients with known or suspected CAD (mean age 70.3±9.5years) were enrolled. All patients did not have any significant coronary stenosis on X-ray coronary angiography (CAG) at the time of MRI acquisition. By using a 1.5T MRI scanner, breath-hold phase contrast cine MRI images of coronary sinus (CS) were obtained to assess the blood flow of CS both at rest and during adenosine triphosphate (ATP) infusion. Coronary flow reserve (CFR) was calculated as CS blood flow during ATP infusion divided by CS blood flow at rest. CMD was defined as CFR<2.5 according to a previous study. Patients were allocated to four groups based on the CHADS2 score (group1: CHADS2 score=0, group2: CHADS2 score=1; group3: CHADS2 score=2, and group4: CHADS2 score≥3).

RESULTS

Mean CFR was 2.81±0.95 (77.6±32.7mL/min at rest; 208.2±86.5mL/min during ATP infusion, p<0.001). Patients with higher CHAD2 score had lower CFR. In the multiple logistic regression analysis, CHADS2 score was independently associated with CFR (odds ratio=0.61, 95% confidence interval: 0.37-0.99, p=0.049).

CONCLUSIONS

Higher CHADS2 score was significantly associated with lower CFR evaluated by phase contrast cine MRI.

Impairment of Coronary Flow Reserve Evaluated by Phase Contrast Cine-Magnetic Resonance Imaging in Patients With Heart Failure With Preserved Ejection Fraction

BACKGROUND

Phase contrast (PC) cine-magnetic resonance imaging (MRI) of the coronary sinus allows for noninvasive evaluation of coronary flow reserve (CFR), which is an index of left ventricular microvascular function. The objective of this study was to investigate coronary flow reserve in patients with heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

We studied 25 patients with HFpEF (mean and SD of age: 73±7 years), 13 with hypertensive left ventricular hypertrophy (LVH) (67±10 years), and 18 controls (65±15 years). Breath-hold PC cine-MRI images of the coronary sinus were obtained to assess blood flow at rest and during ATP infusion. CFR was calculated as coronary sinus blood flow during ATP infusion divided by coronary sinus blood flow at rest. Impairment of CFR was defined as CFR <2.5 according to a previous study. The majority (76%) of HFpEF patients had decreased CFR. CFR was significantly decreased in HFpEF patients in comparison to hypertensive LVH patients and control subjects (CFR: 2.21±0.55 in HFpEF vs 3.05±0.74 in hypertensive LVH, 3.83±0.73 in controls; P<0.001 by 1-way ANOVA). According to multivariable linear regression analysis, CFR independently and significantly correlated with serum brain natriuretic peptide level (β=-68.0; 95% CI, -116.2 to -19.7; P=0.007).

CONCLUSIONS

CFR was significantly lower in patients with HFpEF than in hypertensive LVH patients and controls. These results indicated that impairment of CFR might be a pathophysiological factor for HFpEF and might be related to HFpEF disease severity.

Quantitative evaluation of myocardial fibrosis by cardiac integrated backscatter analysis in Kawasaki disease

Background

Kawasaki disease is an acute, systemic vasculitis that affects the coronary arteries. However, the relationship between myocardial fibrosis and Kawasaki disease has been completely unknown until now. We aimed to provide quantitative information about myocardial fibrosis using cardiac integrated backscatter in Han race Kawasaki disease patients.

Methods

Ninety Kawasaki disease patients and 90 healthy control subjects were recruited. Based on Kawasaki disease status, the patients were categorized into 3 groups: acute, subacute, and convalescence phase. Based on coronary artery status, the Kawasaki disease patients were categorized into 3 groups: without coronary artery lesions, with coronary artery dilation, and with coronary artery aneurysms. All subjects underwent two-dimensional and Doppler examinations to measure clinical echocardiographic parameters. Myocardial fibrosis was detected with calibrated integrated backscatter imaging.

Results

Left ventricle systolic functions were normal in both the Kawasaki disease and control participants. The myocardial calibrated integrated backscatter values of the left ventricles of the acute (p < 0.001), subacute (p < 0.001) and convalescence phase (p < 0.001) Kawasaki disease patients were significantly greater than those of the healthy controls. The left ventricle myocardial calibrated integrated backscatter values were significantly smaller in the Kawasaki disease patients without coronary artery lesions than in the Kawasaki disease patients with coronary artery dilations and coronary artery aneurysms in different phases. The left ventricle myocardial calibrated integrated backscatter results were positively correlated with coronary artery status in the acute (r = 0.331, p < 0.001), subacute (r = 0.456, p < 0.001) and convalescence phases (r = 0.407, p < 0.001) of Kawasaki disease.

Conclusion

Our findings may suggest that myocardial fibrosis occurs during early episodes of Kawasaki disease given uncertainties that exist regarding correlations of calibrated integrated backscatter and myocardial fibrosis.

Comprehensive assessment of impaired peripheral and coronary artery endothelial functions in smokers using brachial artery ultrasound and oxygen-15-labeled water PET

BACKGROUND

Comprehensive evaluation of endothelium-dependent and endothelium-independent vascular functions in peripheral arteries and coronary arteries in smokers has never been performed previously. Through the use of brachial artery ultrasound and oxygen-15-labeled water positron emission tomography (PET), we sought to investigate peripheral and coronary vascular dysfunctions in smokers.

METHODS AND RESULTS

Eight smokers and 10 healthy individuals underwent brachial artery ultrasound at rest, during reactive hyperemia [250mmHg cuff occlusion (flow-mediated dilatation (FMD)], and following sublingual nitroglycerin (NTG) administration. Myocardial blood flow (MBF) was assessed through O-15-labeled water PET at rest, during adenosine triphosphate (ATP) administration, and during a cold pressor test (CPT). Through ultrasound, smokers were shown to have significantly reduced %FMD compared to controls (6.62±2.28% vs. 11.29±2.75%, p=0.0014). As assessed by O-15-labeled water PET, smokers were shown to have a significantly lower CPT response than were controls (21.1±9.5% vs. 50.9±16.9%, p=0.0004). There was no relationship between %FMD and CPT response (r=0.40, p=0.097). Endothelium-independent vascular dilatation was similar for both groups in terms of coronary flow reserve with PET (p=0.19). Smokers tended to have lower %NTG in the brachial artery (p=0.055).

CONCLUSIONS

Smokers exhibited impaired coronary endothelial function as well as peripheral brachial artery endothelial function. In addition, there was no correlation between PET and ultrasound measurements, possibly implying that while smokers may have systemic vascular endothelial dysfunction, the characteristics of that dysfunction may be different in peripheral arteries and coronary arteries.

Vascular health late after Kawasaki disease: implications for accelerated atherosclerosis

Kawasaki disease (KD), an acute vasculitis that primarily affects young children, is the most common acquired paediatric cardiovascular disease in developed countries. While sequelae of arterial inflammation in the acute phase of KD are well documented, its late effects on vascular health are increasingly unveiled. Late vascular dysfunction is characterized by structural alterations and functional impairment in term of arterial stiffening and endothelial dysfunction and shown to involve both coronary and systemic arteries. Further evidence suggests that continuous low grade inflammation and ongoing active remodeling of coronary arterial lesions occur late after acute illness and may play a role in structural and functional alterations of the arteries. Potential importance of genetic modulation on vascular health late after KD is implicated by associations between mannose binding lectin and inflammatory gene polymorphisms with severity of peripheral arterial stiffening and carotid intima-media thickening. The changes in cholesterol and lipoproteins levels late after KD further appear similar to those proposed to be atherogenic. While data on adverse vascular health are less controversial in patients with persistent or regressed coronary arterial aneurysms, data appear conflicting in individuals with no coronary arterial involvements or only transient coronary ectasia. Notwithstanding, concerns have been raised with regard to predisposition of KD in childhood to accelerated atherosclerosis in adulthood. Until further evidence-based data are available, however, it remains important to assess and monitor cardiovascular risk factors and to promote cardiovascular health in children with a history of KD in the long term.

Detection of diminished response to cold pressor test in smokers: assessment using phase-contrast cine magnetic resonance imaging of the coronary sinus

PURPOSE

The purposes of this study were to evaluate the reproducibility for measuring the cold pressor test (CPT)-induced myocardial blood flow (MBF) alteration using phase-contrast (PC) cine MRI, and to determine if this approach could detect altered MBF response to CPT in smokers.

MATERIALS AND METHODS

After obtaining informed consent, ten healthy male non-smokers (mean age: 28±5 years) and ten age-matched male smokers (smoking duration ≥5 years, mean age: 28±3 years) were examined in this institutional review board approved study. Breath-hold PC cine MR images of the coronary sinus were obtained with a 3T MR imager with 32 channel coils at rest and during a CPT performed after immersing one foot in ice water. MBF was calculated as coronary sinus flow divided by the left ventricular (LV) mass which was given as a total LV myocardial volume measured on cine MRI multiplied by the specific gravity (1.05 g/mL).

RESULTS

In non-smokers, MBF was 0.86±0.25 mL/min/g at rest, with a significant increase to 1.20±0.36 mL/min/g seen during CPT (percentage change of MBF (∆MBF (%)); 39.2%±14.4%, p<0.001). Inter-study reproducibility for ∆MBF (%) measurements by different MR technologist was good, as indicated by the intraclass correlation coefficient of 0.93 and reproducibility coefficient of 10.5%. There was no significant difference between smokers and non-smokers for resting MBF (0.85±0.32 mL/min/g, p=0.91). However, ∆MBF (%) in smokers was significantly reduced (-4.0±32.2% vs. 39.2±14.4%, p=0.011).

CONCLUSION

PC cine MRI can be used to reproducibly quantify MBF response to CPT and to detect impaired flow response in smokers. This MR approach may be useful for monitoring the sequential change of coronary blood flow in various potentially pathologic conditions and for investigating its relationship with cardiovascular risk.

Relationship between coronary flow reserve evaluated by phase-contrast cine cardiovascular magnetic resonance and serum eicosapentaenoic acid

BACKGROUND

Long-term intake of long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) is associated with a low risk for cardiovascular disease. Phase-contrast cine cardiovascular magnetic resonance (PC cine CMR) can assess coronary flow reserve (CFR). The present study investigates the relationship between CFR evaluated by PC cine CMR and the serum EPA.

METHODS

We studied 127 patients (male, 116 (91%); mean age, 72.2 ± 7.4 years) with known or suspected coronary artery disease (CAD). X-ray coronary angiography revealed no significant coronary arterial stenoses (defined as luminal diameter reduction ≥ 50% on quantitative coronary angiogram (QCA) analysis) in all study participants. Breath-hold PC cine CMR images of the coronary sinus (CS) were acquired to assess blood flow of the CS both at rest and during adenosine triphosphate (ATP) infusion. We calculated CFR as CS blood flow during ATP infusion divided by that at rest. Patients were allocated to groups according to whether they had high (n = 64, EPA ≥ 75.8 μg/mL) or low (n = 63, EPA < 75.8 μg/mL) median serum EPA.

RESULTS

CFR was significantly lower in the low, than in the high EPA group (2.54 ± 1.00 vs. 2.91 ± 0.98, p = 0.038). Serum EPA positively correlated with CFR (R = 0.35, p < 0.001). We defined preserved CFR as > 2.5, which is the previously reported lower limit of normal flow reserve without obstructive CAD. Multivariate analysis revealed that EPA is an independent predictor of CFR > 2.5 (odds ratio, 1.01; 95% confidence interval, 1.00 - 1.02, p = 0.008).

CONCLUSIONS

The serum EPA is significantly correlated with CFR in CAD patients without significant coronary artery stenosis.

Quantification of regional myocardial blood flow estimation with three-dimensional dynamic rubidium-82 PET and modified spillover correction model

PURPOSE

Myocardial blood flow (MBF) estimation with (82)Rubidium ((82)Rb) positron emission tomography (PET) is technically difficult because of the high spillover between regions of interest, especially due to the long positron range. We sought to develop a new algorithm to reduce the spillover in image-derived blood activity curves, using non-uniform weighted least-squares fitting.

METHODS

Fourteen volunteers underwent imaging with both 3-dimensional (3D) (82)Rb and (15)O-water PET at rest and during pharmacological stress. Whole left ventricular (LV) (82)Rb MBF was estimated using a one-compartment model, including a myocardium-to-blood spillover correction to estimate the corresponding blood input function Ca(t)(whole). Regional K1 values were calculated using this uniform global input function, which simplifies equations and enables robust estimation of MBF. To assess the robustness of the modified algorithm, inter-operator repeatability of 3D (82)Rb MBF was compared with a previously established method.

RESULTS

Whole LV correlation of (82)Rb MBF with (15)O-water MBF was better (P < .01) with the modified spillover correction method (r = 0.92 vs r = 0.60). The modified method also yielded significantly improved inter-operator repeatability of regional MBF quantification (r = 0.89) versus the established method (r = 0.82) (P < .01).

CONCLUSION

A uniform global input function can suppress LV spillover into the image-derived blood input function, resulting in improved precision for MBF quantification with 3D (82)Rb PET.

[Kawasaki disease in adult patients]

Kawasaki disease (KD) is a multisystemic vasculitis affecting mainly the skin, mucosa, and lymph nodes. Coronary artery aneurysms occur in 25% of patients but their prevalence is reduced to 4% in those patients treated with intravenous immunoglobulin (IVIg) within 10 days of illness onset. Interesting data recently published relate to physiopathology and diagnosis of the disease. Investigations identified an antigen-driven IgA oligoclonal response directed against cytoplasmic inclusions in KD tissues. An algorithm using laboratory tests and echocardiography has been recently proposed to improve early detection of incomplete KD. Although KD predominantly affects children, it may be also of interest for adult physicians. First, patients may develop long-term cardiovascular event. Coronary artery aneurysms may lead to the development of coronary stenosis or thrombosis. Despite the absence of coronary lesions during the acute phase of the disease, patients may present morphological and functional sequelae of coronary and peripheral arteries at convalescent phase. These potential arterial sequelae require long-term follow-up and treatment of associated cardiovascular risk factors. Although the level of injury seems to be correlated with the severity of initial coronary lesions, long-term course of vascular injuries is poorly known. Second, KD may occur in adults with 91 cases reported in the literature. Twenty-one cases have been reported in HIV infected patients. Intravenous immunoglobulins appear to shorten the disease course. Recent studies highlight the existence of incomplete KD and symptomatic coronary aneurysms in adults. Overall, these data suggest that adult patients with biological or echocardiographic features suggestive of incomplete KD should receive prompt IVIg to prevent coronary artery sequelae.

Assessment of coronary endothelial function using PET

Endothelial dysfunction is the earliest abnormality in the development of coronary atherosclerosis. Several coronary risk factors adversely affect endothelial function. Therefore, a finding of endothelial dysfunction may guide interventions for preventing the development of future cardiovascular events. The non-invasive aspects and coronary specificity of measurements of myocardial blood flow (MBF) using positron emission tomography (PET) with sympathetic stress make it widely applicable for the evaluation of endothelial function. PET MBF measurements with sympathetic stress have been applied to a variety of subjects with coronary risk factors and have been shown to have value for risk assessment in these subjects. Endothelial measurement using PET remains an ideal research tool for the study of the pathophysiology of several cardiac diseases. PET is also well suited for the acute and longitudinal evaluation of treatment. Thus, the continued development of this approach for the evaluation of new treatment effects should be expected.

Noninvasive quantification of coronary endothelial function by SPECT imaging in children with a history of Kawasaki disease

PURPOSE

The feasibility of coronary function estimation by single photon emission computed tomography (SPECT) has been recently demonstrated. The aim of this study was to apply SPECT imaging in patients with previous Kawasaki disease (KD) to assess the coronary functional status at long-term follow-up of the acute phase of the disease.

METHODS

Sixteen children with a history of KD underwent 99mTc-sestamibi imaging at rest and during the cold pressor test (CPT). Myocardial blood flow (MBF) was estimated by measuring first transit counts in the pulmonary artery and myocardial counts from SPECT images. Coronary endothelial function was expressed as the ratio of the CPT to rest MBF.

RESULTS

Six KD patients without coronary artery lesions served as controls and ten with coronary artery aneurysms during the acute phase of the disease were separated into two groups: group 1 (n=4) with regressed and group 2 (n=6) with persistent aneurysm at follow-up. The estimated coronary endothelial function was higher in controls compared to patients with coronary artery aneurysms (2.5±0.3 vs 1.7±0.7, p<0.05). A significant difference in coronary endothelial function among groups was found (F=5.21, p<0.02). Coronary endothelial function was higher in patients of group 1 than in those of group 2 (1.9±0.6 vs 1.4±0.7, p<0.02).

CONCLUSION

SPECT may be applied as a noninvasive method for assessing coronary vascular function in children with a history of KD, demonstrating an impaired response to the CPT, an endothelial-dependent vasodilator stimulus. These findings reinforce the concept that coronary endothelial dysfunction may represent a long-term sequela of KD.

Ultrasound tissue characterization of the myocardium in patients after Kawasaki disease

We sought to determine if changes in myocardial physical properties, detected by ultrasound tissue characterization (UTC), are present in asymptomatic children years after an acute episode of Kawasaki disease (KD) and if such changes are related to coronary artery aneurysms (CAs). Myocardial UTC analysis was performed 4.8 + or - 3.4 years after acute KD in 22 patients, mean age 6.6 + or - 3.4 years, with or without CA, who had a normal ECG and normal left ventricular (LV) systolic and diastolic function by echocardiography. Twenty-two age-matched subjects were studied as controls. Cyclic variation of integrated backscatter (cvIBS) and calibrated integrated backscatter (cIBS) were assessed in 16 LV myocardial segments in each patient and control. We found large differences in the UTC data between patients and controls: cvIBS, 7.8 + or - 0.8 vs 8.9 + or - 0.6 dB; cIBS, 28.6 + or - 3.2 vs 25.2 + or - 1.0 dB (P\10-3 for both). The average values of cIBS and cvIBS did not differ significantly between KD patients with and patients without CA or stenosis. In conclusion, UTC analysis demonstrated significant differences in myocardial tissue properties between KD patients and controls, despite similar measures of LV function, independent of coronary artery abnormalities. UTC analysis might improve risk stratification for KD patients.

Quantitative analysis of coronary endothelial function with generator-produced 82Rb PET: comparison with 15O-labelled water PET

PURPOSE

Endothelial dysfunction is the earliest abnormality in the development of coronary atherosclerosis. 82Rb is a generator-produced positron emission tomography (PET) myocardial perfusion tracer that is becoming more widely used. We aimed to (1) develop a method for quantitative assessment of coronary endothelial function using the myocardial blood flow (MBF) response during a cold pressor test (CPT) in smokers, measured using 82Rb PET, and (2) compare the results with those measured using 15O-water PET.

METHODS

MBF was assessed at rest and during the CPT with 82Rb and 15O-water in nine controls and ten smokers. A one-compartment model with tracer extraction correction was used to estimate MBF with both tracers. CPT response was calculated as the ratio of MBF during the CPT to MBF at rest.

RESULTS

At rest, measurements of MBF for smokers vs controls were not different using 15O-water (0.86±0.18 vs 0.70±0.13, p=0.426) than they were using 82Rb (0.83±0.23 vs 0.62±0.20, p=0.051). Both methods showed a reduced CPT response in smokers vs controls (15O-water, 1.03±0.21 vs 1.42±0.29, p=0.006; 82Rb, 1.02±0.28 vs 1.70±0.52, p<0.001). There was high reliability [intraclass correlation coefficients: 0.48 (0.07, 0.75)] of MBF measurement between 82Rb and 15O-water during the CPT.

CONCLUSION

Using a CPT, 82Rb MBF measurements detected coronary endothelial dysfunctions in smokers. 82Rb MBF measurements were comparable to those made using the 15O-water approach. Thus, 82Rb PET may be applicable for risk assessments or evaluation of risk factor modification in subjects with coronary risk factors.

Arterial stiffness in the young: assessment, determinants, and implications

Arterial stiffness describes the rigidity of the arterial wall. Its significance owes to its relationship with the pulsatile afterload presented to the left ventricle and its implications on ventricular-arterial coupling. In adults, the contention that arterial stiffness as a marker and risk factor for cardiovascular morbidity and mortality is gaining support. Noninvasive methods have increasingly been adopted in both the research and clinical arena to determine local, segmental, and systemic arterial stiffness in the young. With adoption of these noninvasive techniques for use in children and adolescents, the phenomenon and significance of arterial stiffening in the young is beginning to be unveiled. The list of childhood factors and conditions found to be associated with arterial stiffening has expanded rapidly over the last decade; these include traditional cardiovascular risk factors, prenatal growth restriction, vasculitides, vasculopathies associated with various syndromes, congenital heart disease, and several systemic diseases. The findings of arterial stiffening have functional implications on energetic efficiency, structure, and function of the left ventricle. Early identification of arterial dysfunction in childhood may provide a window for early intervention, although longitudinal studies are required to determine whether improvement of arterial function in normal and at-risk paediatric populations will be translated into clinical benefits.

Atypical and incomplete Kawasaki disease

Kawasaki disease (KD) is the most common systemic vasculitis in childhood after Henoch-Schonlein purpura, and the most common cause of acquired heart disease among children living in Western countries. Its diagnosis relies on clinical findings; laboratory tests are useful to rule out other causes of unexplained fever but are not specific for the diagnosis of KD. Numerous efforts to produce a diagnostic algorithm have been made, but without success. Expert opinion is therefore required in doubtful cases, especially those that lack classical criteria (the so-called atypical or incomplete cases). Renal, gastrointestinal, neurologic, pulmonary and ocular involvements have all been described. Infants may be at higher risk of complications since recognising manifestations of the disease might be more difficult in this group. Approaches to treatment and follow-up of KD are changing in parallel with changes in concepts of what constitutes classical and incomplete KD. Guiding this evolution is the probability that the diagnosis is actually KD, the duration of the child's illness and the desired effects of therapy. Until a gold standard for diagnosing KD is available, these therapeutic decisions will continue to be made on an individual basis.

Cardiac positron emission tomography: current clinical practice

In the last two decades, the field of nuclear cardiology has experienced significant progress. The introduction of positron emission tomography (PET) imaging represented a major breakthrough that has significantly contributed to a better understanding of physiology and pathophysiology of several heart diseases. Currently, PET imaging is recognized as a well-established method to assess cardiac perfusion, function, metabolism, and viability. This article summarizes the main clinical applications of state-of-the art cardiac PET technology.

Transthoracic echo-Doppler assessment of coronary microvascular function late after Kawasaki disease

The goal of this study was to demonstrate that Doppler transthoracic echocardiography (TTE) may represent a valuable tool for the noninvasive demonstration of coronary microvascular dysfunction in children with previous Kawasaki disease (KD) by the measurement of coronary flow reserve (CFR) during cold pressor test (CPT). Twenty-five children with previous KD (mean follow-up, 4.6 +/- 2.6 years) were included in the study-16 with no evidence of coronary artery lesions (CALs(-)) by TTE and 9 with coronary aneurysms (CALs(+)). Seventeen age-matched healthy subjects were also recruited. Diastolic peak velocity was measured by pulsed Doppler both at rest (DPV(Rest)) and during CPT (DPV(CPT)) in the anterior descending artery. CFR was calculated as DPV(CPT)/DPV(Rest). KD patients demonstrated significantly higher values of DPV(Rest) (0.21 +/- 0.05 vs 0.13 +/- 0.01 cm/sec, p < 0.0001) and DPV(CPT) (0.33 +/- 0.07 vs 0.27 +/- 0.03 cm/sec, p < 0.005). CFR was reduced in KD compared to control subjects (1.5 +/- 0.4 vs 2.1 +/- 0.2, p < 0.0001). CFR was decreased in a similar manner in both CALs(+) patients (1.4 +/- 0.4, p = 0.002 vs controls) and CALs(-) patients (1.6 +/- 0.4, p < 0.0001 vs controls). Doppler TTE at rest and during CPT may represent a valuable modality for CFR evaluation in children with a history of KD. CFR is significantly reduced in KD patients independently of the presence of CALs.

Plasma interleukin-6 and tumor necrosis factor-alpha can predict coronary endothelial dysfunction in hypertensive patients

Coronary endothelial function is impaired in hypertension; however, the severity of this impairment varies among patients. We aimed to identify the predictors of coronary endothelial dysfunction among clinical variables related to hypertension and atherosclerosis. Twenty-seven untreated, uncomplicated essential hypertensive patients and 10 age-matched healthy controls were studied prospectively. Myocardial blood flow (MBF) was measured by using (15)O-water positron emission tomography (PET) at rest and during a cold pressor test (CPT). Coronary vascular resistance (CVR) during CPT was used as a marker of coronary endothelial function. Serum low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides, malondialdehyde-LDL, homeostasis model assessment, high-sensitivity C-reactive protein (hs-CRP), and plasma interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha were also measured. CVR during CPT was significantly higher in hypertensive patients than in healthy controls (114+/-26 vs. 94+/-12 mmHg/[mL/g/min]; p<0.05). By univariate analysis, CVR during CPT was correlated with LDL cholesterol (r=0.38, p<0.05), IL-6 (r=0.46, p<0.02), and TNF-alpha (r=0.39, p<0.05) in hypertensive patients. By multivariate analysis, IL-6 and TNF-alpha were significant independent predictors of CVR during CPT. Elevated plasma IL-6 and TNF-alpha levels were independent predictors of coronary endothelial dysfunction in hypertensive patients. These results suggest that plasma IL-6 and TNF-alpha might be useful for identifying the high risk subgroup of hypertensive patients with coronary endothelial dysfunction and provide an important clue to link systemic inflammation to the development of coronary atherosclerosis.

Are patients after Kawasaki disease at increased risk for accelerated atherosclerosis?

OBJECTIVE

To assess whether patients after Kawasaki disease (KD) have increased risk factors and abnormalities suggestive of early atherosclerosis in systemic arteries.

STUDY DESIGN

In a case-control study, we compared 52 patients after typical Kawasaki disease with varying coronary artery involvement (67% males; mean time from illness episode 11.2 +/- 3.7 years) studied between 10 and 20 years of age with 60 healthy control subjects (50% males). Brachial artery reactivity (BAR) was assessed using vascular ultrasonography, and atherosclerosis risk assessment was performed. Differences between cases and controls and factors associated with endothelial function in cases were determined.

RESULTS

Case patients had lower resting systolic blood pressure (P < .001), lower apolipoprotein AI levels (P < .05), and higher levels of glycosylated hemoglobin (P = .007). There were no significant differences in BAR between case patients and control subjects in response to increased flow (P = .60) and nitroglycerine (P = .93). For case patients, significant factors in multivariable analysis for lower flow-mediated BAR included higher fasting triglyceride levels (P = .04) and lower free fatty acid levels (P < .001). No significant relationship was noted with past or current coronary artery involvement.

CONCLUSION

Patients with KD have some abnormalities for risk factors for atherosclerosis, but systemic arterial endothelial dysfunction is not present in the long term.

Olmesartan, But Not Amlodipine, Improves Endothelium-Dependent Coronary Dilation in Hypertensive Patients

OBJECTIVES

We aimed to compare the effects of the angiotensin II receptor blocker (ARB) olmesartan versus the calcium channel blocker (CCB) amlodipine on coronary endothelial dysfunction in patients with hypertension.

BACKGROUND

Angiotensin II receptor blockers are thought to have greater beneficial effects than CCBs on coronary vasomotion by directly blocking action of angiotensin II.

METHODS

Twenty-six patients with untreated essential hypertension were prospectively assigned to treatment with either olmesartan (27.7 +/- 12.4 mg/day, n = 13) or amlodipine (5.6 +/- 1.5 mg/day, n = 13) for 12 weeks. Changes of corrected myocardial blood flow (DeltaMBF) and coronary vascular resistance (DeltaCVR) from rest to cold pressor were measured by using 15O-water and positron emission tomography before and after treatment. Blood biomarkers including lipids, glucose, insulin, high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-alpha, and superoxide dismutase (SOD) were also measured.

RESULTS

Olmesartan and amlodipine reduced blood pressure (BP) to the same extent (-28.7 +/- 16.2 mm Hg vs. -26.7 +/- 10.8 mm Hg). In the olmesartan group, DeltaMBF tended to be greater (-0.15 +/- 0.19 ml/g/min vs. 0.03 +/- 0.17 ml/g/min, p = 0.09 by 2-way analysis of variance), and DeltaCVR was significantly decreased (7.9 +/- 23.5 mm Hg/[ml/g/min] vs. -16.6 +/- 18.0 mm Hg/[ml/g/min], p < 0.05) after treatment, whereas these parameters did not change in the amlodipine group (DeltaMBF: -0.15 +/- 0.12 ml/g/min vs. -0.12 +/- 0.20 ml/g/min; DeltaCVR: 6.5 +/- 18.2 mm Hg/[ml/g/min] vs. 4.8 +/- 23.4 mm Hg/[ml/g/min]). Serum SOD activity tended to increase (4.74 +/- 4.77 U/ml vs. 5.57 +/- 4.74 U/ml, p = 0.07 by 2-way analysis of variance) only in the olmesartan group.

CONCLUSIONS

Olmesartan, but not amlodipine, improved endothelium-dependent coronary dilation in hypertensive patients independent of BP reduction. These beneficial effects on coronary vasomotion might be via an antioxidant property of ARBs.

Will 3-dimensional PET-CT enable the routine quantification of myocardial blood flow?

Quantification of myocardial blood flow (MBF) and flow reserve has been used extensively with positron emission tomography (PET) to investigate the functional significance of coronary artery disease. Increasingly, flow quantification is being applied to investigations of microvascular dysfunction in early atherosclerosis and in nonatherosclerotic microvascular disease associated with primary and secondary cardiomyopathies. Fully three-dimensional (3D) acquisition is becoming the standard imaging mode on new equipment, bringing with it certain challenges for cardiac PET, but also the potential for MBF to be measured simultaneously with routine electrocardiography (ECG)-gated perfusion imaging. Existing 3D versus 2D comparative studies support the use of 3D cardiac PET for flow quantification, and these protocols can be translated to PET-CT, which offers a virtually noise-free attenuation correction. This technology combines the strengths of cardiac CT for evaluation of anatomy with cardiac PET for quantification of the hemodynamic impact on the myocardium. High throughput clinical imaging protocols are needed to evaluate the incremental diagnostic and prognostic value of this technology.

Kawasaki disease: diagnosis, management and cardiac sequelae

Kawasaki disease (KD) is an acute self-limiting systemic vasculitis of unknown etiology and the most common cause of acquired coronary disease in children aged 6 months to 5 years. The inflammatory process results in coronary arteritis, aneurysmal lesions, arterial thrombotic occlusion or even sudden death. The diagnostic tests are unknown but treatment with immunoglobulin and aspirin is effective at reducing cardiac complications from 25 to 4.7% in the UK. Myocardial, endocardial or pericardial inflammation may occur acutely or many years later and abnormalities of myocardial blood flow may require ongoing medication, interventional catheterization or even cardiac surgery. There are several new drugs that may have important roles to play in managing KD in children and young adults.

Chapter 11 Kawasaki Disease

Kawasaki disease (KD) is an acute febrile systemic vasculitis usually occurring in children younger than five years, and rarely reported in neonates and adults. This chapter discusses the epidemiology, etiology, pathogenesis, clinical manifestations, and treatments of KD. The etiology still remains unknown, although epidemiological and clinical features strongly suggest an infectious cause. Immunological abnormalities in the acute phase of the disease reflect activation of immune system and marked production of cytokines by activated cells. KD has some similarities to toxin-mediated diseases, both from a clinical and an immunological point of view. The role of one or more superantigens competent of stimulating large numbers of T cells produced by certain strains of Staphylococcus or Streptococcus is discussed in the chapter, in the context of the etiology of KD. Atypical cases are those with fever, acute surgical symptoms, or neurological manifestations as presenting signs. Medical history, physical examination, and laboratory tests including elevated white-blood cell (WBC) count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and low hemoglobin, sodium and albumin levels may help to rule out illnesses mimicking KD. Oral or pulsed corticosteroids in children refractory to intravenous immunoglobulins (IVIG) are an alternative and safe treatment.

Is the arterial switch operation as good over the long term as we thought it would be?

Surgical intervention for hearts with transposition, defined as concordant atrioventricular and discordant ventriculo-arterial connections, has been one of the landmark achievements in the field of paediatric cardiac surgery. In the early 1950s, pioneer surgeons attempted to palliate patients with transposed arterial trunks with an early form of the arterial switch operation. As a result of initially dismal outcomes secondary to difficulties with coronary arterial transfer, the unprepared nature of the morphologically left ventricle, and primitive methods for cardiopulmonary bypass, the arterial switch was abandoned in favour of several procedures achieving correction at atrial and venous levels, culminating in the Mustard and Senning operations.1,2These innovative procedures produced the earliest surviving children with transposition. Although the atrial switch procedures achieved widespread acceptance and success during the mid-1960s through the mid-1980s, the search for an operation to return the great arteries to their normal anatomic positions continued. This pursuit was stimulated primarily by the accumulating observations in mid-to-late term follow up studies of: an increasing frequency of important arrhythmic complications, including sinus nodal dysfunction, atrial arrhythmias, and sudden, unexplained death, by the development of late right ventricular dysfunction and significant tricuspid regurgitation in a ventricle potentially unsuited for a lifetime of systemic function by a small but important prevalence of obstruction of the systemic and/or pulmonary venous pathways, and by dissatisfaction with the operative mortality in the subgroup of infants complicated by additional presence of a large ventricular septal defect.3–6As we have already discussed, a number of novel procedures to achieve anatomic correction had been described as early as 1954, but clinical success was not accomplished until 1975, when Jatene and co-workers7astounded the world of paediatric cardiology with their initial description.

Enfermedad de kawasaki

La enfermedad de Kawasaki es una vasculitis sistémica de etiología desconocida que afecta principalmente a niños menores de 5 años. Es actualmente la primera causa de cardiopatía adquirida en la infancia en los países desarrollados, lo que la convierte en una enfermedad de suma trascendencia en el momento actual. No se conoce su etiología, aunque existen fuertes sospechas de que sea infecciosa. El diagnóstico se realiza por criterios clínicos de fiebre persistente de al menos 5 días de duración y 4 de 5 criterios clínicos: cambios en extremidades, exantemas polimorfos, inyección conjuntival no exudativa, cambios en los labios y la mucosa oral y adenopatías > 1,5 cm, habitualmente unilateral. La complicación más frecuente es la dilatación y los aneurismas de las arterias coronarias, la cual ocurre en el 20-25% de los niños no tratados. El tratamiento estándar de la enfermedad es con gammaglobulina intravenosa en dosis de 2 g/kg, antes de los 10 días del comienzo de la enfermedad, más ácido acetilsalicílico oral en dosis antiinflamatorias. El riesgo de lesión coronaria en los niños tratados es del 3-5%.

Myocardial flow reserve is influenced by both coronary artery stenosis severity and coronary risk factors in patients with suspected coronary artery disease

PURPOSE

Myocardial flow reserve (MFR) measurement has an important role in assessing the functional severity of coronary artery stenosis. However, a discrepancy between the anatomical severity of coronary artery stenosis and MFR is often observed. Such a discrepancy may be explained by coronary risk factors. In this study, we aimed to investigate the influence of coronary artery stenosis severity and risk factors on MFR.

METHODS

Seventy-four patients suspected to have coronary artery disease and seven age-matched healthy volunteers were enrolled. Myocardial blood flow (MBF) and MFR were measured using 15O-labelled water PET. Regional MFR was calculated in regions with significant coronary artery stenosis (stenotic regions) and in regions without significant stenosis (remote regions). The contributions of coronary artery stenosis severity and coronary risk factors were assessed using univariate and multivariate analyses.

RESULTS

In stenotic regions, MFR correlated inversely with coronary artery stenosis severity (r=-0.50, p<0.01). Univariate analysis did not show any significant difference in MFR between the patients with and the patients without each risk factor. In remote regions, however, MFR was significantly decreased in the diabetes and smoking groups (each p<0.05). By multivariate analysis, diabetes and smoking were independent predictors of MFR (each p<0.05). In the group with more than one risk factor, MFR was significantly lower (2.78+/-0.79) than in the other group (3.40+/-1.22, p<0.05).

CONCLUSION

MFR is influenced not only by coronary stenosis severity but also by coronary risk factors. In particular, the influence of risk factors should be considered in regions without severe coronary stenosis.

Coronary artery calcifications in the long-term follow-up of Kawasaki disease

BACKGROUND

To determine if detection of coronary artery calcifications in patients with Kawasaki disease may serve as a noninvasive predictor of future coronary artery events.

METHODS

A prospective, cohort pilot study that included 18 patients with Kawasaki disease > 1 year from the acute disease was performed including 9 patients with coronary abnormalities during the acute illness (Group 1) and 9 without coronary abnormalities (Group 2). Patients were classified by echocardiography as having none, resolved, or residual coronary artery abnormalities. Electron beam computed tomography (EBCT) scans were completed using the Agatson coronary calcium scoring system. Intermediate follow-up was performed 2.5 years after EBCT to determine if clinically significant coronary artery events (myocardial infarction or sudden death) had occurred.

RESULTS

Late echocardiographic abnormalities corresponded with the early echocardiographic abnormalities in 5 of 9 patients (P = .029) in Group 1. The late echocardiographic abnormalities significantly correlated with detection of calcifications by EBCT in 4 of 5 patients (95% CI 28%-99%). One patient with residual coronary abnormalities and coronary artery calcifications with the highest calcium score subsequently had a sudden death. Detection of coronary artery calcifications may be predictive of sudden death (P = .056). No residual echocardiographic abnormalities, coronary artery calcifications, or coronary artery events occurred in Group 2 patients.

CONCLUSIONS

Patients with Kawasaki disease with residual coronary abnormalities show EBCT evidence of coronary artery calcifications. Detection of coronary artery calcifications may be useful for risk stratification in the long-term management of patients with Kawasaki disease.

Reduced 123I-BMIPP uptake implies decreased myocardial flow reserve in patients with chronic stable angina

PURPOSE

Long-chain fatty acid (LCFA) is the main energy source for normal myocardium at rest, but in ischemic myocardium, the main energy substrate shifts from LCFA to glucose. 123I-BMIPP is a radiolabeled LCFA analog. In chronic stable angina without previous infarction, we suppose that reduced 123I-BMIPP uptake is related to the substrate shift in myocardium with decreased myocardial flow reserve (MFR). The purpose of this study was to relate 123I-BMIPP uptake to rest myocardial blood flow (MBF), hyperemic MBF, and MFR assessed with 15O-water positron emission tomography (PET).

METHODS

We enrolled 21 patients with chronic stable angina without previous infarction, all of whom underwent 123I-BMIPP single-photon emission computed tomography (SPECT) and 15O-water PET. The left ventricle was divided into 13 segments. In each segment, rest MBF and hyperemic MBF were measured by PET. 123I-BMIPP uptake was evaluated as follows: score 0=normal, 1=slightly decreased uptake, 2=moderately decreased uptake, 3=severely decreased uptake, and 4=complete defect. 123I-BMIPP uptake was compared with rest MBF, hyperemic MBF, and MFR.

RESULTS

The numbers of segments with 123I-BMIPP scores 0, 1, 2, 3, and 4 were 178, 40, 25, 24, and 0, respectively. The rest MBFs for scores 0, 1, 2, and 3 were 0.93+/-0.25, 0.86+/-0.21, 0.97+/-0.30, and 0.99+/-0.37 ml/min/g, respectively. The hyperemic MBFs for scores 0, 1, 2, and 3 were 2.76+/-1.29, 1.84+/-0.74, 1.37+/-0.39, and 1.08+/-0.40 ml/min/g, respectively. The MFRs for scores 0, 1, 2, and 3 were 3.01+/-1.38, 2.20+/-0.95, 1.44+/-0.22, and 1.10+/-0.26, respectively. As 123I-BMIPP uptake declined, hyperemic MBF and MFR decreased.

CONCLUSION

In chronic stable angina without previous infarction, reduced 123I-BMIPP uptake implies decreased MFR.

Diagnosis, treatment, and long-term management of Kawasaki disease: a statement for health professionals from the Committee on Rheumatic Fever, Endocarditis and Kawasaki Disease, Council on Cardiovascular Disease in the Young, American Heart Association

BACKGROUND

Kawasaki disease is an acute self-limited vasculitis of childhood that is characterized by fever, bilateral nonexudative conjunctivitis, erythema of the lips and oral mucosa, changes in the extremities, rash, and cervical lymphadenopathy. Coronary artery aneurysms or ectasia develop in approximately 15% to 25% of untreated children and may lead to ischemic heart disease or sudden death.

METHODS AND RESULTS

A multidisciplinary committee of experts was convened to revise the American Heart Association recommendations for diagnosis, treatment, and long-term management of Kawasaki disease. The writing group proposes a new algorithm to aid clinicians in deciding which children with fever for > or =5 days and < or =4 classic criteria should undergo echocardiography, receive intravenous gamma globulin (IVIG) treatment, or both for Kawasaki disease. The writing group reviews the available data regarding the initial treatment for children with acute Kawasaki disease, as well for those who have persistent or recrudescent fever despite initial therapy with IVIG, including IVIG retreatment and treatment with corticosteroids, tumor necrosis factor-alpha antagonists, and abciximab. Long-term management of patients with Kawasaki disease is tailored to the degree of coronary involvement; recommendations regarding antiplatelet and anticoagulant therapy, physical activity, follow-up assessment, and the appropriate diagnostic procedures to evaluate cardiac disease are classified according to risk strata.

CONCLUSIONS

Recommendations for the initial evaluation, treatment in the acute phase, and long-term management of patients with Kawasaki disease are intended to assist physicians in understanding the range of acceptable approaches for caring for patients with Kawasaki disease. The ultimate decisions for case management must be made by physicians in light of the particular conditions presented by individual patients.

Quantitative Assessment of Regional Myocardial Flow Reserve Using Tc-99m-Sestamibi Imaging-Comparison With Results of O-15 Water PET-

BACKGROUND

The aims of this study were to develop a method for quantitative estimation of the myocardial blood flow index (MBFI) and myocardial flow reserve (MFR) of the whole left ventricle using (99m)technetium (Tc-99m)-sestamibi imaging.

METHODS AND RESULTS

Twenty-two patients with suspected coronary artery disease and 7 controls underwent both Tc-99m-sestamibi imaging and O-15 water positron emission tomography (PET). The global MBFI was calculated on the basis of the microsphere model from the ratio of the myocardial count to the area under the time - activity curve on the aortic arch. The regional MBFI was calculated from the relative distributions of Tc-99m-sestamibi uptake values. The regional MBFI and MFR (Tc-MFR) obtained using single-photon emission computed tomography were compared with the myocardial blood flow (MBF) and MFR (PET-MFR) obtained using PET as the gold standard. Regional MBFI significantly correlated with the MBF obtained using PET. Regional Tc-MFR also correlated with the regional PET-MFR, with some underestimation.

CONCLUSION

These results indicate that regional MBF and MFR may be estimated by dynamic Tc-99m-sestamibi imaging and can be used for the early detection and estimation of the functional severity of coronary lesions without the need for a PET camera.

Coronary artery changes in patients with Kawasaki disease

Kawasaki disease (KD) is an acute, self-limiting, systemic vasculitis of unknown aetiology, which most commonly occurs in children aged 6 mo to 5 y, with a peak incidence at 9-11 mo. The inflammatory process preferentially involves the coronary arteries, potentially resulting in coronary arteritis, aneurysmal lesions, arterial thrombotic occlusion and sudden death. Kawasaki disease is the most common cause of acquired coronary vessel abnormalities in children. The cause of KD is not known, but evidence is presented for an inflammatory response and a genetic predisposition. The diagnostic tests are not yet defined, but treatment with immunoglobulin and aspirin is effective at reducing the risk of cardiac complications from 25% to 4.7% in the UK. Sequelae may occur, either acutely with myocardial, endocardial or pericardial inflammation, or many years after the original illness. There may be abnormalities of myocardial blood flow as assessed by MRI, radio-nucleide studies or echo Doppler. Such abnormalities of coronary arteries may require ongoing medication, interventional catheterization or even cardiac surgery. In the future, we hope to have more accurate diagnostic tests or prophylaxis against the disease, in addition to improved means of determining the susceptibility to or presence of long-term complications.