The Functional Status of the Cardiovascular System in Children Survivors of Oncological Disease

Abstract

According to data of Russian Research Institute of Children Oncology and Hematology, the incidence of oncological disease in children is rather high (220 - 240 new cases in Moscow every year). Nevertheless, when started in due time, an adequate treatment results in complete recovery with favorable longterm prognosis in up to 80% of all cases of lymphoblastic leukemia, 95% of lymphogranulomatosis, 65% of lymphosarcoma, 90% of nephroblastoma, and 100% of retinoblastoma. Most children continue to attend general school after recovery. So, examination of functional status of various physiological systems in children survivors of oncological disease is a topical problem. In treating children with oncological disease, it should be taken into account that their growing and developing physiological systems are highly sensitive to various endogenous and exogenous influences [1‐3]. The most important components of complex oncological disease treatment are radiation and chemotherapy. However, their use can be accompanied by unfavorable long-term side-effects associated with lesions in unaffected tissues and organs (dysfunctions in urogenital, endocrine, cardiorespiratory, and/or locomotor systems). It has been shown [4] that 15-year survivors of oncological disease diagnosed during their childhood and treated chemotherapeutically have increased cardiac mortality rates. In this connection, this work was designed to study the functional status of the cardiovascular system in 7- to 17-year-old children and adolescents with long-lasting remissions after cured malignant diseases. All the children examined were in-patients in the rehabilitation department of Research Institute of Children Oncology and Hematology; they continue their schooling according to the standard curricula. Central hemodynamics was examined with echocardiography (EchoCG) and electrocardiography (ECG). The readings were taken with patients resting in the recumbent position. The following EchoCG parameters were recorded: the systolic and diastolic myocardium thickness in the left ventricular posterior wall; enddiastolic and end-systolic left ventricular size and volume; stroke volume; cardiac output; ejection fraction; systolic shortening fraction; systolic speed of the circulatory myocardial fiber shortening; and the blood ejection time. The ECG was recorded with 12 common leads; it was checked for the presence of various disturbances of cardiac rhythm, intraventricular conductance, myocardial recovery, electrical alternation, or decrease in ECG-wave voltage. The volumetric and tonic parameters of cerebral and antebrachial circulation were determined with focused and tetrapolar impedance plethysmography. The study was performed with 75 patients with histories of various malignant diseases (blood malignancies accounted for approximately 70% of cases examined). According to EchoCG data, about 50% of children examined had various myocardial disorders. Frequently (in 50% of cases) there was a 12‐35% decrease in pumping and contractile myocardium capacity. A 12‐20% thinning of the left ventricular posterior wall (relative to the age-specific norm) was found in 20% of children, and was frequently accompanied by the transition zone shift towards the left thoracic leads. Fifteen percent of patients had a 10‐20% widening of the left ventricle expressed on ECG as an abnormal amplitude ratio of R-wave in left V leads. These disorders were combined in 20% of the children. Cardiac arrhythmia, bradycardia, tachycardia, impairments of intraventricular conductance or myocardial recovery, electrical alternation or decrease in ECG-wave voltage were observed in 20, 22, 14, 75, 26, 18, and 10% of the children, respectively. Changes of this complexity in morphofunctional parameters may be regarded as a manifestation of myocardiac dystrophy. Up to 80% of children examined had impairments of peripheral circulation such as the tonic instability of large cerebral and antebrachial vessels or a significant decrease in the tone of small and medium-size antebrachial vessels; in 50% of cases there were restrictions of venous backflow caused by decreased venous tone. These data are characteristic of the high incidence of vascular dystonias in this group of children.