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Biomedical subjects

P Stojanov

Publications and source records attributed to P Stojanov.

At least 19 recordsLinked to original sources
PubMed2001

Permanent endocardial pacing by cephalic vein access in new-borns and infants--surgical techniques.

Most centers worldwide use permanent endovenous cardiac electrostimulation in children requiring pacing whose body mass is over 10kg. The normal implantation route is via a subclavian vein puncture. In our Center, we have implanted permanent endovenous pacing systems for complete AV block in nine children with a mean body mass 7.4kg (range 2.45-10kg). The endovenous lead was placed using cephalic vein cutdown procedure. To allow 'sliding' during the child's growth, the lead was secured by absorbable sutures.

Humans↗
PubMed1998

Absorbable suture technique: solution to the growth problem in pediatric pacing with endocardial leads.

Endocardial pacing system implantation has been performed in 15 children of mean age 37 months (ranging from 1 day to 89 months). Endocardial lead fixation was performed by means of slowly resorbable suture (Dexon) to allow spontaneous lead migration as the child grows. During a mean follow-up period of 61 months (range 17-108 months), none of the patients needed reintervention for correcting the lead length to allow growth.

Benzenesulfonates↗
PubMed1994

[Comparative analysis of vascular injuries during times of peace and war].

The authors present results of reconstructive surgical procedures in 127 non-war and 59 war vascular injures operated on in the last ten and 2 years, respectively. Non-war injures were dominated by blunt trauma, while fire arms and explosives caused most of war injuries. Two thirds of the patients were subjected to primary, and one third to secondary operations. As much as 85% of secondary operations were made in cases of war injuries. The most common reasons for inappropriate primary operations were: incomplete diagnostics, inappropriate surgical procedure and technical errors. About two thirds of the cases were isolated vascular injuries, and one third were combined injuries where in addition to blood vessels, bones and peripheral nerves were also affected. Topographically, the upper and lower extremities were most commonly affected. Most of the operations were complex reconstructive procedures such as graft interpositions or by-passes, and less frequently only suture of a blood vessel or end-to-end anastomosis were made. Fasciotomy was an auxillary method used in all patients with late vascularization syndrome, and exposure in a special "tent" in patients with wound infection. Early success was noted on 88% of operated patients. In 12% of them amputation was performed. Primary amputation (without attempts of reconstruction) was performed in 4% out of the total number of patients. After primary operations they performed (127) the authors had to undertake amputation because of failure of the primary surgery in 4% of patients, while after secondary reconstructions (primary operations performed elsewhere) amputations were necessitated in 23% out of 57 patients. A significant difference was noted which directly correlated with the number of primary and secondary operations after war (28%) and non-war (6%) injuries.

Blood Vessels↗
PubMed1992

Assessment of long-term stability of chronic ventricular pacing thresholds in steroid-eluting electrodes.

Sixteen patients with Medtronic 4003 steroid-eluting electrodes implanted in the ventricular position were followed over 5 years. In each patient a special type of Medtronic 2443 pacemaker was implanted to allow programming of output at 1.35 V. Chronic threshold values in these patients measured at an output of 1.35 V were stable over the first 18 months of follow-up. Mean values were: 0.06 +/- 0.03 msec at 6 months and 0.08 +/- 0.02 msec at 18 months; these did not differ from each other significantly. However, during the period from 18 to 36 months postimplantation, a significant increase in mean pacing threshold was observed: 0.08 +/- 0.02 msec at 18 months postimplantation versus 0.14 +/- 0.05 msec at 36 months (P < 0.01). After 36 months, the chronic pacing threshold remained stable until the end of the 5-year follow-up period. Further long-term study of chronic threshold behavior of steroid-eluting electrodes measured at low amplitudes is warranted.

Cardiac Pacing, Artificial↗
PubMed1988

Association between stimulated QT interval and ventricular rhythm disturbances: influence of autonomic nervous system.

To examine the association between ventricular rhythm disturbances and changes in the pacemaker-induced stimulated T interval (STIM-T interval), we compared findings from monitoring of two patient groups. The first group consisted of 15 patients with QTX microprocessor pacemakers and the second group consisted of 198 patients with documented ventricular rhythm disturbances and coronary artery disease (CAD). In the first group, which was free of ventricular rhythm disturbances and manifest coronary artery disease, the STIM-T interval was measured every 4 hours over a 36-hour period at four pacemaker frequency settings (70, 80, 90, and 100) in order to observe the circadian variation of the STIM-T interval as a function of changes in autonomic nervous system (ANS) tone. The second group was comprised of patients with CAD and over 30 VES/hrs (Lown grade classification 1-5), and taking no antiarrhythmic medication. These patients were followed using 24-hour Holter monitoring over a minimum of 23 hours and with less than 5% artifact/recording. Information regarding mean hourly heart rate, total number of VES, VES pairs, VT runs, and ischemic episodes in this group was compared with changes in the STIM-T interval in the first group. The STIM-T interval was found to be shorter during the day and longer at night at all heart rate settings. The total frequency of VES, of VES pairs, VT runs, and ischemic episodes in the second group varies in a similar circadian fashion. The greatest total number of VES, of VES pairs, VT runs, and ischemic episodes was recorded in the waking hours, at the same time when the STIM-T interval is the shortest, while this number was significantly lower during sleep, when the STIM-T interval of the first group is the longest. This coincidence of circadian variation pattern between STIM-T interval in group I, and ventricular arrhythmias and ischemic episodes in group II, suggests that alterations in ANS tone reflected in the STIM-T interval may be an important factor in the occurrence of these untoward events.

Adult↗
PubMed1986

Target lead--low threshold electrode.

Acute and chronic threshold measurements were compared for three different electrodes: the Medtronic Target Tip model 4011, the Medtronic Ring Tip Model 6971 and the Siemens-Elema Carbon Tip Model 412S. The results of this study show that acute thresholds are lower with the Target Tip lead as compared to the other two. This finding applies to chronic thresholds as well. The results of this study favor programming to lower output energies while maintaining adequate safety margins with this lead system.

Electrodes, Implanted↗
PubMedDate not supplied

[The popliteal artery entrapment syndrome].

The authors are presenting 8 patients with 9 cases of popliteal artery entrapment syndrome. There were one female, and 7 male patients with average age of 36.4 (25-54) years. Six cases were manifested with acute, 2 with chronic foot ischemia, while one case was asymptomatic. For diagnosis a combination of Doppler sonography and transfemoral angiography, was used. Eight cases were operated using posterior, while in one medial approach to the popliteal artery. The types I and IV of the popliteal artery entrapment syndrome were found in one case, type II in two cases, type III in 4 cases, while in one case a type of syndrome had not to be identified. During the operation the resection of the anomalous muscle and reconstruction of the popliteal artery, were done in 8 cases. In one case muscle resection or arterial reconstruction, were not necessary. The early potency rate and limb salvage, were 100%, while long term potency rate after mean follow up period of 6.3 years was 83.5%. The acute or chronic foot ischemia in health, young persons without typical atherosclerotical risk factors, suggests on popliteal artery entrapment syndrome.

Adult↗
PubMedDate not supplied

[Metabolic parameters in the evaluation of frequency-adaptive sensors in pacemakers].

A comparison was made between metabolic parameters during exercise in patients with implanted dual sensor VVIR pacemakers. We analyzed two groups of patients with implanted dual sensor responsive pacemakers. The first group was composed of 14 patients (mean age 37.7 years) who had implanted Topaz pacemakers. The second group of 9 patients had a Legend Plus (mean age 44.7 years). A control group consisted of 54 healthy individuals (mean age 40.4 years). Testing was performed on treadmill, using a stepwise staircase loading CAEP protocol. Directly measured and mathematically calculated parameters used in assessment of metabolic impact of pacemaker function were: minute ventilation (MV), MV/body surface, MV/body mass unit, oxygen consumption, oxygen consumption/body surface, oxygen consumption/heart rate (oxygen pulse), oxygen consumption/body mass unit, carbon dioxide production, respiratory index. The majority of the observed parameters revealed no statistically significant difference between the control group and the patients with dual sensor or single sensor controlled rate response. However, oxygen pulse showed a statistically significant difference when comparing the group with single sensor controlled rate response with dual sensor controlled rate response and control group (p < 0.05). Other parameters indicating an advantage of dual sensor controlled rate were the time period of reaching anaerobic threshold (respiratory index) and exercise duration. They both displayed a statistically significant difference between dual sensor controlled rate response and single sensor rate response (p < 0.05) with no significant difference compared to control group (p > 0.05).

Adult↗
PubMedDate not supplied

Sudden rate drop intervention rate level in patients with new 'clarity' pacemakers and carotid sinus syndrome.

BACKGROUND: In patients in whom syncopal episodes are mainly caused by occasional drops in heart rate, Sudden Rate Drop intervention feature intends to provide high rate intervention pacing. New Vitatron Medical B.V. pacemaker system Clarity DDDR, provides AN option FOR recognizing Sudden Rate Drop and responding by intervention pacing until it detects the recovering. MATERIAL AND METHODS: In patients with carotid sinus syndrome it is possible to provoke this situation BY sinus carotidus massage. We have implanted 10 of these devices in our center, 2 of which in patients with hypersensitive carotid sinus syndrome. In both patients, we activated sudden rate drop intervention on DDD mode pacing and applied protocol for testing the necessary level of Sudden Rate Drop Intervention Rate. Both patients gave their informed consent to be submitted to this testing. Pacemaker software assumes rate intervention level of 110 bpm. We tested our patients for rate levels of 90 and 110 bpm. Massaging the carotid sinus during 5 seconds, we provoked Sudden Rate Drop Intervention 10 times, in each patient, 5 times at intervention rate of 90 and 5 times at 110 bpm. Patients were unaware of the programmed intervention rate and were merely expected to report any different sensations experienced during the testing. RESULTS: In all 20 tests, pacemaker responded to sudden rate drop elicited by carotid sinus massage (100%), which was verified by selected event recordings. After the massage, neither of the patients registered any sensations at sudden rate drop intervention rate level of 90 bpm in a total od 10 tests (100%), while 8 out of 10 massages at 110 bpm intervention rate provoked palpitations (80%). On the grounds of this testing, we concluded that lowering of Sudden Rate Drop Intervention Rate Level from 110 BPM to 90 BPM does not affect the reliability of system reaction, but changes patient's awareness of heart beats. CONCLUSION: As a final conclusion, it should be said that basic prerogatives of a pacing system: safety and efficacy with minimal energy consumption, and in this case, quality of life option that a patients practically does not feel intervention when it occurs, are all met.

Awareness↗
PubMedDate not supplied

[Analysis of programmed pacing rate levels in patients with the carotid sinus hypersensitivity syndrome and implanted Clarity pacemakers].

New Clarity DDDR pacemaker system (Vitatron Medical B.V.) Clarity DDDR, provides an option for recognizing sudden rate drop and responding by intervention pacing until it detects the recovering. In patients in whom syncopal episodes are mainly caused by occasional drops in heart rate, Sudden Rate Drop Intervention feature intends to provide high rate intervention pacing. We have implanted 10 of these devices in our Centre, 2 of which in patients with hypersensitive carotid sinus syndrome. In patients with carotid sinus syndrome it is possible to provoke this situation by sinus caroticus massage. In both patients, we activated Sudden Rate Drop Intervention on DDD mode pacing and used protocol for testing the necessary level of sudden Rate Drop Intervention Rate. Both patients gave their informed consent to be submitted to this testing. Pacemaker software assumes rate intervention level of 110 bpm. We tested our patients for rate levels of 90 and 110 bpm. Massaging the carotid sinus during 5 seconds, we provoked sudden Rate Drop Intervention 10 times, in each patient, 5 times at intervention rate of 90 and 5 times at 110 bpm. Patients were unaware of the programmed intervention rate and were merely expected to report any different sensations experienced during the testing. In all 20 tests, pacemaker responded to sudden rate drop elicited by carotid sinus massage (100%), that was verified by selected event recordings. After the massage, no patient experienced any sensation at sudden rate drop intervention rate level of 90 bpm in a total od 10 tests (100%), while 8 of 10 messages at 110 bpm intervention rate provoked palpitations (80%). We concluded that lowering of Sudden Rate Drop Intervention Rate Level from 110 BPM to 90 BPM did not affect the reliability of system reaction, but changes of patient's awareness of heart beats. As a final conclusion, it should be said that basic prerogatives of a pacing system are: safety and efficacy with minimal energy consumption, and in this case, quality of life option that a patient practically does not feel intervention when it occurs, are all met.

Cardiac Pacing, Artificial↗
PubMedDate not supplied

[Femoro-popliteal bypass in situ].

The authors present early and late results of femoro-popliteal/crural reconstruction where "in situ" technic is used. Of 35 patients 10 had the third stage of occlusive disease by Fontain, and 25 were in the fourth stage. Therefore the reconstruction consisted of "limb salvage procedure". The aim of the study was to present the possibilities of this technique in cases with ischaemic extremities and poor "run off". The early potency of prosthesis within the first month was 97% (34 patients) and late (after one year) 91% (32 patients). In three patients, in early postoperative stage, AV fistulas were found and successfully surgically treated. AV fistulas were caused by non-ligated branches of the saphenous vein. Thus, a conclusion was drawn that intraoperative control angiography vas of great importance. Better potency of prosthesis, when compared to the quality of saphenous vein graft and when used "in situ", over the classical method was achieved thanks to the following facts: no damage of the intima caused by hydrostatic dilatation; possible use of a vein whose diameter is less than 4 mm; no damage of adventitia (vasa vasorum) due to the slower degenerative process of the vein wall; impossible graft torsion; low compliance level between the graft and the small artery, and small artery caused by the conic shape of graft.

Female↗
PubMedDate not supplied

Results of 132 PTFE (Gore-Tex) bifurcated graft implantations.

One hundred and thirty-two PTFE bifurcated prosthetic grafts were implanted during the course of a bicentre study conducted at the abovenamed institutions from 1982 to 1986. The study included 118 males and 14 females with an average age of 62 years. One hundred and eighteen patients suffered from aorto-iliac occlusive disease and 14 from abdominal aortic aneurysms (AAA). Five patients had already undergone previous surgery (redo operations), with extirpation of thrombosed Dacron prostheses. Proximal end to end anastomoses were fashioned in 94 cases (71.2%), while end to side anastomoses were performed in 38 cases (28.8%). The distal anastomoses were to the iliac arteries in 11 cases, the common femoral artery in 89 cases and the deep femoral artery in 32 cases.

Aorta, Abdominal↗
PubMedDate not supplied

[Aneurysms of the carotid arteries].

The aim of the paper is the presentation of the treatment of aneurysms of the extracranial carotid artery and review of literature. Aneurysms of extracranial carotid arteries (common carotid artery, external carotid artery and cervical part of the internal carotid artery) are very rate [1, 2]. In 1979 McCollum from the Baylor University (Houston, Texas) reported 37 cases over a 21-year period [3]. Moreau from France reported 38 cases over a 24-year period [4]. Mayo clinic experience includes 25 cases in the 40-year period [5]. According to Schechter 835 extracranial carotid artery aneurysms were reported in literature until 1977. These and the other aneurysms of the extracranial carotid artery can be partially or completely thrombosed, can cause distal embolization, or compression of adjacent structures, and can be ruptured [4, 9]. Therefore, the mortality rate in non operated patients with carotid artery aneurysm is 70% [10]. Over the period from January 1, 1985 to December 31, 1996 at the Centre of Vascular Surgery within the Institute of Cardiovascular Diseases of the Serbian Clinical Centre in Belgrade, 12 patients with 13 extracranial carotid artery aneurysms were treated. Nine of them (75%) were males and 3 (25%) females, average age 58.22 (21-82) years. There were two traumatic (gunshot wounds) and one anastomotic (after carotid subclavian bypass with PTFE graft) pseudoaneurysms, and 10 true atherosclerotic aneurysm. Three (23%) aneurysms were on the common and 9 (77%) on the cervical part of the internal carotid artery. Two (15%) aneurysms were in the form of asymptomatic pulsatile neck mass, 7 (54%) with CVI or TIA, three (23%) with compression of the cranial nerves and one (8%) was ruptured. Twelve (92%) patients were treated surgically, while one asymptomatic aneurysm in a 82-year old female patient was not operated due to high risk. The intraoperative findings revealed one complete and 11 partial thromboses of the aneurysmal sac. In 3 patients with fusiform aneurysms, thrombectomy and aneurysmorrhaphy were performed. One traumatic pseudoaneurysm was treated with aneurysmectomy and lateral suture of the artery. In 3 patients aneurysmectomy and end to end anastomosis were done, while in three aneurysmectomy and saphenous vein graft interposition. In case of ruptured aneurysm of the internal carotid artery aneurysmetomy and arterial ligature were carried out, while in case of anastomotic pseudoaneurysm after carotid subclavian bypass, aneurysmectomy and new carotid subclavian bypass with PTFE graft, were performed. During the study no intrahospital mortality was recorded. One patient died 5 years after the operation due to myocardial infarction. The mean follow-up period was 4 years and 2 months (6 months to 11 years). The early and late potency rates were 100%. Two (17%) CVI and two transient cranial nerve paresies were noticed immediately after the operation. In literature male/female ration in patients with extracranial carotid artery aneurysms is 2:1 [2, 4, 7], but in our study it was 5:1. One (10%) of our patients had a bilateral carotid artery aneurysm. According to literature data the incidence of bilateral localization of extracranial carotid artery aneurysms with atherosclerotic origin is 21% [1]. Of 12 surgically treated aneurysms in our study, 9 were of atherosclerotic origin, two were traumatic and one anastomotic pseudoaneurysms. Today, most of true extracranial carotid artery aneurysms are of atherosclerotic origin [7, 20-25]. However, true extracranial carotid artery aneurysms can be developed due to: infection of the arterial wall (mycotic forms) [26-37]; nonspecific [23] or irradiation arteritis [38], fibromuscular dysplasia [4, 8, 15, 16, 39]. The most frequent types of false extracranial carotid artery aneurysms are traumatic pseudoaneurysms [32, 50-54] and anastomotic pseudoaneurysms [53, 59, 60]. There are also dissecting extracranial carotid artery aneurysms developed after isolated spontaneous d

Adult↗