**13. Vasculitis**

In patients with vasculitis, especially those with coronary artery involvement, anginal complaints may be seen at an early age. Myocardial infarction and unexpected sudden cardiac death can be determined [44–47]. In some cases the clinical findings are non-specific such as abdominal pain, myalgia and muscle pain, and the diagnosis can only be made by postmortem study [46].

Polyarteritis Nodosa (PAN) is a rarely seen severe vasculitis that affects small and medium diameter arteries in particular. Diagnosis of the disease is made according to the criteria defined in 1990 by the American College of Rheumatology (**Table 7**). The disease can cause infarction in the organs by creating transmural necrotising vasculitis mostly in medium diameter arteries [46]. In addition to the heart, the kidneys, the gastrointestinal system, the skin, the nervous system, the joints and the muscles may be affected. The cardiac effect is less compared to the other systems. A coronary involvement alone has been reported in few cases [41].


**Table 7.** Diagnostic criteria for PAN.

thinning and fibrosis in the MI area may be seen in echocardiographic examination and in unaffected parts, compensatory hypertrophy may be present. Although it is difficult to apply in infants, endomyocardial biopsy is the gold standard in myocarditis. The death of myocites and inflammatory cells may be seen in biopsy material [36]. Another diagnostic method is cardiac MRI, which requires general anaesthesia. An increase in cardiac signal and increased myocar-

Hypertrophic cardiomyopathy is characterised by a global thickening of the heart muscle. It should be kept in mind especially in children with exercise-related chest pain [36]. The incidence in the general population is 1 per 500 births and genetic transfer is autosomal dominant. Hypertrophy seen in the ventricular septum together with movement of the mitral valve anteriorally causes a narrowing of the left ventricle outlet [36]. Especially during exercise, this narrowness may cause a decrease in cardiac output and sudden death [38]. Shortness of breath and chest pain are frequent complaints. Situations such as exercise which reduces the pre-load and increases the after-load, tachycardia or dehydration, exacerbate the narrowing of the left ventricle outlet [38].

Sudden cardiac death is defined as death occurring within 1 hour without the emergence of any prodromal finding [39]. A significant cause of sudden cardiac death in children is MI. Previous studies have reported that chest pain is seen in few cases of MI-related sudden cardiac death. More frightening is that a large proportion of these cases suffer sudden cardiac death at rest [40]. Cigarette smoking and dyslipidaemia have been determined as significant risk factors for sudden cardiac death related to coronary artery disease in children and young adults [40].

In patients with vasculitis, especially those with coronary artery involvement, anginal complaints may be seen at an early age. Myocardial infarction and unexpected sudden cardiac death can be determined [44–47]. In some cases the clinical findings are non-specific such as abdominal pain, myalgia and muscle pain, and the diagnosis can only be made by post-

Polyarteritis Nodosa (PAN) is a rarely seen severe vasculitis that affects small and medium diameter arteries in particular. Diagnosis of the disease is made according to the criteria defined in 1990 by the American College of Rheumatology (**Table 7**). The disease can cause infarction in the organs by creating transmural necrotising vasculitis mostly in medium diameter arteries [46]. In addition to the heart, the kidneys, the gastrointestinal system, the skin, the nervous system, the joints and the muscles may be affected. The cardiac effect is less compared to the other systems. A coronary involvement alone has been reported in few cases [41].

dial contrast involvement is seen on cardiac magnetic resonance imaging [37].

**11. Hypertrophic cardiomyopathy**

114 Myocardial Infarction

**12. Sudden cardiac death**

**13. Vasculitis**

mortem study [46].

Coronary artery involvement can occasionally be seen in Takayasu arteritis, which tends to involve larger vessels than PAN [48–50]. It has also been reported that Paediatric MI can be seen in Behçet's disease [45].

## **14. Slow coronary flow phenomenon**

Slow coronary flow phenomenon is a microvascular disease characterised by slow progress of the contrast dye within the vessel, which is not obstructive coronary artery flow [51]. Despite evaluation as a benign clinical setting, it is concerning for families and physicians because of the relationship with MI and anginal symptoms. In addition, the mechanism and clinical outcomes of the disease are not yet fully understood.

Occasionally, clinical findings can be seen in children with ST-segment elevation myocardial infarction (STEMI) [51]. On coronary angiography, there is no vessel obstruction or it is close to normal, but the peripheral blood flow is noticeably slow. Studies of these patients have shown cellular oedema, thickening in the capillary endothelium, fibromuscular hyperplasia, myofibril disorganisation and microvascular thickening, causing endothelial dysfunction [52, 53].
