[Atrio-biventricular electrostimulation in the treatment of congestive heart failure. Case report]. / Atrio-biventrikulska elektrostimulacija u lijecenju kongestivnog zatajivanja srca. Prikaz bolesnika.

Over the past few years, indications for permanent cardiac pacing have been broadened. Accordingly, American Heart Association and American College of Cardiology included dilated cardiomyopathy, hypertrophic obstructive cardiomyopathy and pacing for prevention of atrial fibrillation into indications for permanent cardiac pacing. Studies have described favourable effect of dual chamber cardiac pacing in congestive heart failure in dilated cardiomyopathy, regardless of etiology. In the past two years, even more beneficial effect was associated with multisite, biventricular cardiac pacing. On the basis of the reported results, a multisite pacemaker InSync was implanted to a patient with dilated cardiomyopathy (NYHA class IV), who was also on the list for heart transplantation, and who fulfilled other criteria for implantation of multisite pacemaker. During the eleven-month follow-up, functional improvement, better 6-minute walking test and enhanced quality of life of the patient were observed, which is in accordance with the literature data.

[Management of surgery patients with implanted cardiac pacemakers]. / Postupak s kirurskim bolesnikom--nosiocem elektrostimulatora srca.

Patients having cardiac pacemaker implanted may be subjected to various general surgery procedures. Application of electrosurgery for the purpose of resection and coagulation, provides a high frequency electric field which produces electric voltage on the electrodes of the pacing system. This voltage may be detected within the pacing system, and various arrhythmias can be provoked in correlation with underlying rhythm and mode of pacing. Preoperative patient control and proper pacemaker programming can prevent the pacing malfunctions due to the electrosurgery application. Appropriate positioning of the neutral electrode in relation to the pacing system avoids the electric fields intersection and decreases their interference.

[Shock caused by electrical current]. / Sok izazvan udarom elektricne struje.

The authors elaborate the most frequent causes of electroshock and consequences to the human body thereof. Recent advances in modern medical technology increase the hazard of the electroshock. Tissue burns, asphyxia, CNS destruction and ventricular fibrillation are possible consequences. Depending on the electric current strength, the organism may be a subject of either a macroshock or a microshock. The methods of microshock prevention in hospital environment are disclosed. Two patients are presented, being treated at the Institute of Anesthesiology and Intensive Care.

Possibilities of ultrasound catheters.

Ultrasound catheters offer the possibility of various non-imaging applications. Some of these applications, now in different stages of development, have been studied and will be described here in some detail. Ultrasonically marked catheters have different applications. The catheter has a miniature marker transducer mounted at the tip or some other place of interest. Initially, this device was used to localize the pacing lead tip in the heart. Connected to a transponder of a passive type this device can generate a visible localization mark on the echograph screen. The basically same system can be used for early detection of cracking of the pacing lead insulation. In this case the marker transducer works as a high-frequency signal generator and detects characteristic capacitance changes better than other methods. The electronic circuit for measurement is built into the pacemaker. Other non-imaging applications have also been studied. The marker transducer can be used for echo ranging of the distance between a His bundle fulguration electrode and the structure to be destroyed. Such an automatic 'proximity fuse' can help to avoid the firing of energy at too great a distance from the His bundle. Technology of implantable defibrillators yields the possibility for a double transducer arrangement, one transducer mounted at the patch and the other being the marker transducer. Using on-line distance measurement this arrangement enables early detection of abnormal movement of the ventricle wall, thus detecting deterioration of the muscle function before it is electrically evident. The measurement was simulated in-vitro. Measurement of axial blood flow using transit time methods, instead of Doppler, was also experimentally studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Properties of ultrasonically marked leads.

We have developed an ultrasonic marking system for pacing leads and the electrophysiological study of catheters. The aim of this study was to evaluate the accuracy of our system, its usability in the measurement of performance of implanted leads, and to investigate the potential of electrical shock and ultrasonic hazard. The measurements have shown that different applications require specific electronic design, involving some compromise between accuracy and sensitivity. A higher sensitivity at the beginning of the ultrasonically guided cardiac lead implantation yields poorer accuracy. Quantitative measurements show that accuracy can be subsequently improved by reduction of sensitivity of the marking system. The transponder marking circuit is better suited for general use and the passive electronic circuit is better suited for multiple electrode electrophysiological studies. Experiments concerning electrical safety show that in the worst failure case, the energy of the marking system released within the heart is less than 10(-9) J per pulse within the pacing frequency spectrum and the current was below 50 microamperes. Ultrasound intensities were within the safety limits set by international and national organizations. The experiments using the marking system for detection of the pacing lead failure showed that the system can yield an early warning of the lead malfunction. The system can significantly reduce the exposure of the medical staff and the patients to x rays as well as improve patient follow-up accuracy.