RU2355444C1 - Method of optimisation of frequency-adaptive atrioventricular delay in dounle-chamber electric cardiostimulators - Google Patents

Abstract

FIELD: medicine; arrhythmology.

SUBSTANCE: re-programming of implanted in patient's body double-chamber electric cardiostimulator to mode of atrial stimulation AAI is performed. At the same time under control of surface electrocardiogram, frequency-increasing atrial electric stimulation is carried out starting from frequency which is 10 pulses a minute higher than spontaneous sinus rhythm and increasing frequency of electrostimulation with 10-pulses-a-minute step until tachycardia-dependent second degree artrioventricular block is reached, initially and after that at each step of electrostimulation measurement of St-QRS interval is carried out, to measured St-QRS value 20-30 ms are added and it is considered optimal value of atrioventricular delay for each frequency stage and said values for each frequency are programmed into electrocardiostimulator as atrioventricular delay.

EFFECT: increase of efficiency of frequency-adaptive atrioventricular delay in patients with preserved atrioventricular conduction.

1 tbl, 2 dwg

Description

The invention relates to medicine, namely to arrhythmology, and can be used when programming two-chamber pacemakers (EX) for quick and accurate individual selection of frequency-adaptive (or dynamic) atrioventricular delay in patients with preserved spontaneous atrioventricular conduction.

Bicameral stimulators due to the sequential application of electrical impulses to the atrial and ventricular myocardium allow for synchronized physiological stimulation. One of the main parameters of such EX is the atrioventricular delay (AVZ), which is the time between the application of pulses to the atrium and ventricle. AVZ is a programmable parameter and can be changed by a doctor in the range from 50 ms to 400 ms. It is generally recognized that the definition of individual AVZ and its programming allows not only to synchronize the work of the heart chambers, but also to improve intracardiac hemodynamics. An important indicator is the so-called frequency-adaptive AVZ (CHAVZ), that is, changing depending on the heart rate (HR), which allows you to adapt atrial-ventricular synchronization to physical and emotional stress.

A known method for optimizing the frequency-adaptive atrioventricular delay in two-chamber pacemakers based on a mathematical algorithm [1].

Moreover, in a patient with an implanted two-chamber pacemaker, the CHAVZ function is introduced by means of percutaneous programming, then the base (lower) rhythm driving frequency and the base AVZ (i.e., AVZ at the base frequency) are programmed. After making these adjustments, the pacemaker automatically changes the value of the AVZ, acting according to a mathematical algorithm

AVDx = (AVDp-38,4-VLRL / 8) + X / 8,

Where

AVDx - atrioventricular delay at the present heart rate, in ms;

AVDp - base AVZ, in ms;

VLRL - time interval (in ms) corresponding to the base frequency;

X is the time interval (in ms) corresponding to the present frequency.

For example, in a patient with a basic frequency of 60 pulses per minute (VLRL = 1000 ms) and a basic AVZ of 180 ms, the frequency-adaptive AVZ will be

at heart rate = 100 per minute (X = 600 ms)

AVD100 = (180-38.4-1000 / 8) + 600/8 = 92 ms,

at heart rate = 120 per minute (X = 500 ms)

AVD120 = (180-38.4-1000 / 8) + 500/8 = 79 ms.

Thus, with an increase in heart rate, the pacemaker automatically reduces the AVZ according to the mathematical algorithm introduced by the manufacturer. This method is distinguished by ease of use, since the doctor programs only two parameters and turns on the CHAVZ function, and its change to each frequent happens automatically.

However, this method has a significant drawback in relation to patients with preserved atrioventricular conduction (with isolated sinus node dysfunction, transient atrioventricular block). At rest, the atrioventricular conduction in these patients is carried out through the atrioventricular node. However, during physical exertion (during an increase in heart rate), an automatic frequency-adaptive decrease in AVZ occurs. As a result, the value of CHAVZ becomes less than spontaneous (natural) AVZ and electrical stimulation of the right ventricle begins.

Figure 1 illustrates this phenomenon on the example of one patient. Figure 1 (3) reflects the onset of physical activity, which is accompanied by an increase in heart rate. However, the reduction rate of automatic CHAVZ (Fig. 1, (1)) exceeds the reduction rate of natural AVZ (i.e., the St-QRS interval; Fig. 1, (2)). This leads to stimulation of the right ventricle, which begins at a frequency of 80 pulses per minute, that is, from the moment the graphs intersect (Fig. 1, (4)).

This process is accompanied by the loss of physiological excitement and contraction of the right ventricle, the occurrence of interventricular and intraventricular dysynchrony, which leads to delay of the left ventricle in relation to the right ventricle. This phenomenon leads to tachy-mediated dyssynchrony and worsens the patient's tolerance to physical activity, causing a number of unpleasant sensations.

The aim of this invention is to increase the efficiency of optimization of frequency-adaptive AVZ in patients with preserved atrioventricular conduction.

This goal is achieved by the fact that, based on the increasing electrical stimulation of the right atrium, preliminary analysis of its own atrioventricular (AV) conduction is carried out, after which programming of the largest ChAVZ is carried out in order to maximize its own AV conduction during physical activity and minimize electrical stimulation of the right ventricle.

The method is as follows:

a two-chamber electrical stimulator implanted in the patient’s body is programmed for atrial stimulation (AAI),

under the control of a surface electrocardiogram, atrial pacing is increased, starting from a frequency 10 pulses per minute higher than the frequency of the spontaneous sinus rhythm, and the pacing is increased with a step of 10 pulses per minute until a tachy-dependent atrioventricular block of the second degree is reached,

initially and then at each step of electrical stimulation, the interval of St-QRS is measured, that is, the interval from the spike of the pacemaker to the beginning of the spontaneous QRS complex (figure 2, (2)),

20-30 ms are added to the measured value of St-QRS and the optimal CHAVZ value is obtained for each frequency (Fig. 2, (1)),

The pacemaker is reprogrammed into the dual-chamber stimulation mode and the appropriate value of the optimal CHAVZ, but not more than 250 ms, is entered into its program for each frequency.

Two groups of patients with sinus node dysfunction and transient atrioventricular blockade were compared. Patients of the first group (n = 6) underwent implantation of 2-chamber pacemakers manufactured by Vitatron with an automatic algorithm for changing AVZ. Patients of the second group (n = 6) underwent implantation of 2-chamber pacemakers manufactured by Medtronic, which made it possible to program individual values of AVZ at different frequencies, after which ChAVZ was optimized in these devices according to the method proposed by us.

The groups were comparable by gender, age, and arrhythmic diagnosis (table 1). There were also no significant differences in the degree of exercise tolerance according to the 6-minute walk test. However, after implantation of pacemakers and their programming, patients of the second group reliably noted an increase in exercise tolerance. In patients of the first group: tolerance increased in one patient, worsened in two patients, and remained unchanged in another two patients. Thus, there was no significant change in the tolerance of physical activity in these patients, and patients of the second group could go 79 m further in 6 minutes than patients of the first group (p <0.05). All patients underwent daily monitoring of the electrocardiogram. According to this study, it was noted that in all patients of the first group during physical exertion, right ventricle was stimulated, which began at a frequency of 115.8 ± 9.2 per minute. On the contrary, only one patient of the second group showed short-term stimulation of the right ventricle, which began at a frequency of 150 per minute and was not accompanied by a feeling of physical discomfort in this patient.

Table 1 Comparison of two methods of optimization Options I group (n = 6) II group (n = 6) R Men: women 3: 3 3: 3 NS Average age, years 56.9 ± 6.7 59.7 ± 7.9 NS 6-min distance walk (initially), m 388.3 ± 29.7 369.9 ± 21.1 NS 6-min distance walk (after surgery), m 381.9 ± 39.3 461.1 ± 19.6 <0.05 Stimulation of the right ventricle during physical activity,% of patients one hundred% 16.7% <0.05 The frequency at which the "inclusion" of stimulation of the right ventricle occurred, in minutes 115.8 ± 9.2 150 <0.05 Note: NS are unreliable differences.

Thus, the proposed method eliminated unwanted and useless stimulation of the right ventricle and thereby increased exercise tolerance in patients with implanted dual-chamber pacemakers. The method is simple to use and can be used in patients with no signs of congestive heart failure and with preserved AV after implantation of two-chamber pacemakers in any medical institution that has an arrhythmologist on staff.

Literature

1. Claude Daubert, Philippe Riter, Philippe Mabo et al. Optimization of AV delay during pacing in DDD and DDDR modes // In the book “New Prospects for Pacing” edited by J. Muzhik, D. Egorov and Serge Barold. - St. Petersburg., 1995 .-- S. 293-327.

Claims (1)

A method for optimizing the frequency-adaptive atrioventricular delay in two-chamber pacemakers, including reprogramming a pacemaker, characterized in that a two-chamber pacemaker implanted in the patient’s body is programmed for atrial stimulation mode AAI, under the control of a surface electrocardiogram, an atrial pulsating heart rate is performed at 10 p.m. exceeding the frequency of spontaneous sinus rhythm, and increase the frequency of electrostim step 10 pulses per minute until a tachysensitive atrioventricular block of the second degree is reached, initially and then at each step of electrical stimulation, the interval of St-QRS is measured, 20-30 ms are added to the measured value of St-QRS and considered its optimal value of atrioventricular delay for each frequency steps and these values for each frequency are programmed into the pacemaker as an atrioventricular delay.

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