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Biomedical subjects

J Machejek

Publications and source records attributed to J Machejek.

7 recordsLinked to original sources
PubMed2001

[The effect of changes in stroke volume on QT dispersion during long-term DDD and VVI pacing].

UNLABELLED: The aim of this study was to evaluate the alterations of stroke volume (SV) on the QT dispersion (QTD) as a result of different pacing modes (DDD, VVI) and programmed AV delays (AVD). MATERIAL AND METHODS: We studied 60 patients (pts) (22 F, 38 M) in mean age 67.5 +/- 7.5 yrs in whom DDD pacemakers were implanted due to complete atrioventricular block (AVB III degree). 10 pts had coronary artery disease (CAD)--"CAD" subgroup, 14 pts arterial hypertension (AH)--"AH" subgroup, 27 pts CAD and AH--"AH + CAD" subgroup. The control group consisted of 9 pts without structural heart disease, but with AVB III degree, paced in DDD mode. Previous myocardial infarction was recognised in 7 patients in "CAD" subgroup and in 7 patients in "AH + CAD" subgroup. Left ventricular hypertrophy was detected in 4 men in "AH" subgroup and in 8 patients in "AH + CAD" subgroup. In all cases basic rate of the pacemaker was programmed at 70/min. Resting ECG showed all atrial and ventricular complexes captured. AVD optimization was based on the measurements of SV by Doppler echocardiography. QT intervals (QT) were measured from 12-lead ECG at 50 mm/sec. speed. QTD was calculated as the difference between maximal and minimal QT. It was measured at optimal AVD (with highest SV--opt. DDD) and "unoptimal" AVD (unopt. DDD) programmed AV intervals and then in VVI mode (with lowest SV) after 24 hrs following reprogramming of the pacemaker. RESULTS: In the whole population, in DDD mode, we found a strong correlation between SV and QTD (r = -0.655; p < 0.01). In VVI mode SV was significantly lower than in unopt. DDD (78.7 ml vs 90.0 ml, p < 0.001) and QTD was significantly greater (74.3 ms vs 69.2 ms, p < 0.05). The modifications in AVD and conversion of pacing mode (VVI to DDD) leading to maximal SV resulted in decreased QT dispersion. The highest SV (128.9 ml at opt. DDD) and the lowest QTD (48.3 ms at opt. DDD) were seen in the controls, but changes in dispersion were the least and insignificant during different pacing modes. In CAD; AH + CAD pts, we observed the lowest SV (61.7 ml; 74.9 ml at VVI respectively) and the highest QTD (77.8 ms; 80.9 ms at VVI respectively). In these pts, the modifications of AVD and conversion of pacing mode (VVI to opt. DDD) leading to maximal SV (106.8 ml; 115.9 ml in CAD and AH + CAD pts, respectively) resulted in decreased QTD (53.9 ms; 56.6 ms, respectively). During DDD pacing there was significant correlation of QTD to SV (r = -0.680; r = -0.656, respectively). In CAD pts with myocardial infarction or in AH pts with LV hypertrophy the correlation of SV to QTD was stronger (r = -0.937, r = -0.886, p < 0.025, respectively). We didn't find the correlation in the control group (r = -0.318). CONCLUSIONS: Programming of different AVD and pacing modes significantly influences QTD in CAD and/or AH pts. QTD reflects hemodynamic status of these paced pts.

Adult↗
PubMed2001

[QT dispersion in DDD and VVI paced patients after myocardial infarction or with left ventricular hypertrophy].

The aim of this study was to assess the alterations of stroke volume (SV) on the QT dispersion (QTD) as a result of different pacing modes and programmed AV delays in patients (pts) after myocardial infarction (MI) or with left ventricular hypertrophy (LVH). We studied 14 MI pts (9 M, 5 F) in mean age 72.3 +/- 3.7 yrs (Group I) and 12 pts with LVH (7 M, 5 F) in mean age 67.3 +/- 5.9 yrs (Group II), in whom DDD pacemakers were implanted due to complete atrioventricular block. The control group (Group III) consisted of 9 pts without MI or LVH. In all cases basic rate of the pacemaker was programmed at 70/min. Resting ECG showed all atrial and ventricular complexes captured. AV delay optimization was based on the measurements of SV by Doppler echocardiography. QT intervals (QTi) were measured from 12-lead ECG at 50 mm/s speed. QTD was calculated as the difference between maximal and minimal QTi. It was measured at optimal (opt. DDD, with highest SV) and "unoptimal" (unopt. DDD) programmed AV intervals and then in VVI mode (with lowest SV) after following reprogramming of the pacemaker. In Group I and II, a strong correlation between SV and QTD was found (R = 0.816 and -0.897, respectively). In control group, it was insignificant (R = -0.339). In VVI mode SV was significantly lower than in unopt. DDD (in Mi pts: 56.1 ml vs 71.1 ml, respectively, p < 0.01; in LVH pts: 64.1 ml vs 96.7 ml, respectively, p < 0.005) and QTD was significantly greater (74.8 ms vs 66.8 ms, respectively, p < 0.005 and 70.0 ms vs 53.5 ms, respectively, p < 0.005). In LVH pts or MI pts programming of different AV intervals and pacing modes significantly influences QTD.

Aged↗
PubMed2000

[Multi-site pace making for dilated cardiomyopathy].

Dual chamber pacing (DDD) has been reported to be effective in patients with dilated cardiomyopathy (DCM). Other works, however, show contradictory results. Deleterious effects resulting from desynchronization of the right and left ventricular contraction have been suggested. In patients with end-stage DCM and severe congestive heart failure multisite pacing may be associated with fast and sustained hemodynamic improvement.

Cardiac Pacing, Artificial↗
PubMed1999

[Possible therapeutic applications for contemporary pacemakers].

Pacemaker therapy has undergone widespread application in the clinical practice since the sixties. Nowadays the dynamic development of pacemaker technology has become clearly visible. Recommendations for their implantation became more common over last years. The aim of this paper was to describe few models of modern cardiostimulators present at our medical market as well as their role in antiarrhythmic therapy.

Arrhythmias, Cardiac↗
PubMed1993

[Hemodynamic significance of atrio-ventricular sequence in the example of an observed case].

A case of a 62 year old man with chronic complete atrio-ventricular block but persistent electrical and mechanical atrial activity is presented. The patient was treated by ventricular pacing of the VVI type. During cardiac catheterization right atrium, right ventricle and pulmonary pressure were recorded at basal conditions; right ventricle contractility index and cardiac output were also estimated. An elevation of right atrial pressure simultaneously with a fall of right ventricle and pulmonary pressure were repeatedly observed. These changes were a consequence of atrio-ventricular sequence disorders resulting in un-coordination of atrial and ventricular contractions. Hemodynamic parameters were restored to the physiological range only during the chance appearance of normal atrio-ventricular sequence. The presented observations support the known fact that ventricular pacing in patients with complete atrio-ventricular block may lead to serious hemodynamic disturbances.

Arrhythmias, Cardiac↗