Diagnostic and therapeutic strategies for resistant arterial hypertension--focus on countries with emerging economies.

Arterial hypertensionis an important worldwide health problem. Its relevance relates both to the high incidence and prevalence in all adult communities and to the high risk of serious and potentially fatal cardiovascular events due to hypertension. Resistant hypertension is defined as a blood pressure (BP) remaining above goal (>140/90 mm Hg) despite the use of at least 3 optimally dosed antihypertensive drugs from different classes, with one of the drugs being a diuretic. The exact prevalence of RH is unknown, but it is generally estimated at 10-20% of hypertensive patients. The aim of this review article is to address several important issues: (1) How to diagnose true RH ? (2) What is the optimal state-of-art management of RH in the light of the most recent scientific evidence and what is the role of various medical specialties in this process ? (3) Are there any country specific issues related to diagnosing and treating of RH in Kazakhstan and if so, how to tackle them ?Long-lasting resistant hypertension increases by 50-80% the risk of major cardiovascular events (myocardial infarction, stroke) and end-organ damage. (heart failure, vascular dementia, chronic kidney disease). Adherence to well chosen therapy is the key factor in achieving blood pressure control and this must be based on adequate patient education and universal access to drug therapy. Thus, early recognition and appropriate management of RH must be among the top priorities of all public health initiatives to reduce the burden of cardiovascular diseases (Tab. 2, Fig. 1, Ref. 31).

Noninvasive assessment of local myocardium repolarization changes using high resolution surface ECG mapping.

A method using body surface potential maps for assessment of myocardium lesions with changed repolarization is presented and suitable mapping system is introduced. Differences between normal and altered QRST integral maps together with torso volume conductor model were used to determine the equivalent dipole representing the lesion. Performance of the method was studied on simulated data. Changed repolarization was modeled by shortening of myocyte action potentials in regions typical for stenosis of the main coronary arteries. The equivalent dipole estimated the positions of small lesions with a mean error of 9+/-4 mm (17+/-14 mm for larger transmural lesions). The subepicardial or subendocardial character of the lesions was reflected in the dipole orientation. Tests of the method on patients after myocardial infarction that underwent coronary intervention on a single coronary vessel showed that in 7 of 8 successfully treated patients the dipole position matched well with the treated vessel. A small dipole moment in another patient indicated unsuccessful treatment. The method was implemented in a new 128-channel mapping system. Its active electrodes, battery powered measuring unit and optical computer interface help to minimize noise in ECG and guarantee patient's safety. The results suggest that the method and mapping system offer useful tools for noninvasive identification of local repolarization changes in the myocardium.

Endothelial dysfunction and the clinical application.

The vascular endothelium is a large organ that secretes numerous factors regulating vascular tone, cell growth, platelet and leukocyte interactions and thrombogenesis. Endothelial dysfunction is an early event in atherogenesis and is also important in establish coronary artery disease. Over the past decade a noninvasive technique has evolved to evaluate flow-mediated vasodilation, an endothelium-dependent function. Procedure is realised on the brachial artery. The stimulus provokes the endothelium to release nitric oxide with subsequent vasodilation that can be imaged and quantitated as the index of vasomotor function. (Fig. 1, Ref. 2.).

[Occurrence of abnormal late ventricular potentials in myocardial ischemia and the determination of risk of sudden cardiac death in patients after myocardial infarct]. / Výskyt abnormálnych neskorých komorových potenciálov pri ischémii myokardu a pri urcovaní rizika náhlej srdcovej smrti u pacientov po infarkte myokardu.

BACKGROUND: The crucial step in prevention of sudden cardiac death (SCD) is a method of a precise and most accessible identification of those patients with ischaemic cardiac disease (ICD), especially after MI, who are highly presumptive candidates of malign ventricular arrhythmias. The selection of individuals exposed to risk, and individual judgment of the threat to patients after MI is a complex problem. Patients after MI are endangered by reinfarction, cardiac failure, heart wall rupture and primary ventricular tachyarrhythmia. Stratification of patients exposed to a presumably higher risk of probable new coronary event and malign ventricular arrhythmia with an early decision to intervene, gains practical clinical significance. Similarly, it is important to identify also the patients after MI exposed to lower risk, who need no interventional therapeutical procedure. The cardiologic practice utilizes several examinatory procedures and tests, prevailingly of non-invasive character. AIMS AND OBJECTIVES: The study reviews the latest information on pathophysiology and current level of clinical interpretation of non-invasive ecg procedure from the field of high-resolution electrocardiography including the late ventricular potentials (LVP). The study is aimed at: a) presentation of a review of available information from the field of electrophysiology and clinical electrocardiography and the mechanism of impact of myocardial ischaemia on the existence of high-frequency, but at the same time extremely low-amplitude potentials abnormalities in the course of QRS complex and S-T segment (LVP), b) presentation of a review on the informative value and clinical significance produced by non-invasively detected electrophysiological heterogeneity of myocardium during ischaemia, aiding the short-term and long-term prognosis judgments in patients with ICD, especially after undergoing its most serious form--myocardial infarction. Beside the group analysis the study is also aimed at individual non-invasive judgment of risk of the development of malign ventricular arrhythmias in patients with acute coronary syndromes. (Fig. 3, Ref. 41.)

[Evaluation of the Q wave in leads II, III and aVF. II. Impulse conduction disorders , hypertrophy of the cardiac muscle, pre-excitation, focal and diffuse changes in the cardiac muscle and other causes]. / Hodnotenie kmitu Q vo zvodoch II, III, aVF. II. Poruchy vedenia vzruchov, hypertrofia srdcového svalu, preexcitácia, loziskové a difúzne zmeny srdcového svalu a dalsie príciny.

The authors present a brief account of contemporary findings in the literature on the evaluation of the Q wave in the electrocardiogram in leads II, III and aVF in disorders of the conduction of impulses (also combination with focal lesions of the heart muscle), in preexcitation of various extent, in hypertrophy and different focal and diffuse changes of the heart muscle. They mention briefly also other cardiac and extracardiac causes of the development and persistence of the Q wave in leads, II, III, aVF. They reached the main conclusion that isolated evaluation of this phenomenon only from the electrocardiogram can lead to erroneous conclusions, therefore they advocate comprehensive evaluation of the clinical condition of these patients (in indicated cases with extension of the range of ECG examinations by vectorcardiography and mapping of electric potentials of the heart on the body surface; echocardiography and scintigraphy may prove valuable).

Use of selected quantitative parameters of the electric field of the heart in evaluating the presence and site of preexcitation.

Electrocardiographic methods play a decisive role in evaluation of the health condition of subjects with WPW pattern. The authors examined 54 patients with WPW pattern with different degrees of preexcitation. The presence of preexcitation and the localization of its focus was determined by surface electrocardiographic mapping using the original Czechoslovak computer equipment KARDIO-SMEP 01.0. The duration of ventricular activation was determined according to root mean square signals. By means of potential and temporo-spatial analysis of peak negative regions of instantaneous maps (in 2 ms intervals) they determined the duration of the period of proper preexcitation, of fusion of the two activation events, and of the end depolarization of the ventricles. In localizing the preexcitation focus they proceeded according to the criteria of Benson et al. (1982) with individual evaluation of quantitative preexcitation parameters of ECG maps and according to vector analysis of the delta wave. Quantitative and temporo-spatial evaluation of the mutual relationship of the two activation events in WPW pattern allows to establish reliably the presence, degree and focus localization of preexcitation even at a low degree of preexcitation and at a low-potential level of the preexcitation surface activity on ECG maps.

Evaluation of the state of health of subjects with W-P-W syndrome.

Topical questions in evaluating the state of health in the least risk-exposed group of subjects with the W-P-W syndrome are dealt with: the recognition of preexcitation, the possibility of confusing the W-P-W syndrome with the postinfarction state, the occurrence of abnormal T waves after suppression of preexcitation, and the ECG dynamics after physical exercise. On the basis of ECG and normal results of non-invasive polygraphic examination (systole phase analysis--systolic time intervals) it is possible to divide the least-risk group of persons with preexcitation (with an otherwise normal heart and without paroxysmal tachycardia) into five subgroups (with growing risk) and to evaluate the ability of a person with preexcitation to engage in sports; to carry out military service etc. The mentioned non-invasive examinations are the basic prerequisites in every subject with the W-P-W syndrome and in symptomatic patients before more detailed electrophysiological examination.

Determination of the preexcitation focus in the W-P-W picture by isopotential body-surface mapping.

Experiences with the determination of the preexcitation focus in 13 patients with W-P-W syndrome aged 18-62 years are presented. The data of ECG mapping from the chest surface and the abdominal wall were processed by computer. For classification of the maps the criteria elaborated by Yamada et al., da Ambroggi et al., and Benson et al. were used. It was possible to determine on their basis the preexcitation focus in all examined subjects, although a reduced system of ECG leads was employed. Surface ECG mapping makes possible a more precise location of the preexcitation, which is of great clinical importance for the indication of surgical treatment, determination of prognosis and of working ability.