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Biomedical subjects

P Petrovic

Publications and source records attributed to P Petrovic.

At least 19 recordsLinked to original sources
PubMed2001

The loss of circadian heart rate variations in patients undergoing mitral valve replacement and Corridor procedure--comparison to heart transplant patients.

We have presently demonstrated that when added to mitral valve replacement (MVR) the corridor procedure is 75% efficient in restoring and maintaining sinus rhythm in patients with chronic atrial fibrillation (AF), caused by rheumatic mitral valve disease, (follow up 13.9months). In the same patient population, we observed that the typical day-night cycle heart rate (HR) variations were lost and our present study concentrates on this subject. Heart rate variability analysis based on 24-h Holter ECG recording (StrataScan 563 DelMar Avionics) or hospital discharge (12th-14th postoperative days) was performed in 3 patient groups: Group I: Patients with a Corridor procedure added to MVR (12pts, m/f 10/2, mean age 47.3+/-7.5yr); Group II (control): with patients MVR performed through the left atrial approach, without additional antiarrhythmic procedures (10pts, m/f 3/7 mean age 51.5+/-6.7yr), and Group III: heart transplant recipients (5pts, mean age 46.4+/-11.22yr). We analyzed the hourly heart rate over 24-h period divided into three 8-h segments (07-14h; 15-22h and 23-06h). Statistical comparison of mean hourly heart rate values was made between the three time periods of Holter monitoring. The Corridor procedure performed with mitral valve replacement resulted in conversion of sinus rhythm in 75% of patients (Group I), but postoperative heart rate variability analyses based on Holter monitoring disclosed that the mean heart rate was not statistically significantly difficult between the three 8-h segments of the day-night (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). In the second group (classical MVR), statistically significant differences in mean HR variation existed between the three 8-h intervals (P<0.05), and although atrial fibrillation occurred postoperatively physiologic circadian heart rate variations were preserved. With the Corridor procedure, both atria were surgically and electrically isolated and chronotropic function of the ventricles was restored by creating a small strip of atrial tissue with isolated sinus node and atrio-ventricular node, connected to the ventricles. This technique produced heart denervation nervous system influence, producing the loss of circadian HR variations, similar to the transplanted heart.

Cardiac Surgical Procedures↗
PubMed2001

Anatomy of the cavernous sinus region.

The cavernous region was examined in 20 fetuses, injected with Micropaque, and in 5 adults. The lateral wall of the cavernous region in fetuses was noticed to have four layers. The superficial membrane represents the dural sheath. The second membrane of dense connective tissue involves the trochlear nerve. The third layer, formed by loose connective tissue, involves the oculomotor nerve, and the ophthalmic and maxillary division. The fourth layer, which represents the lateral wall of the cavernous sinus, involves the abducent nerve. The meningohypophyseal trunk can be complete or incomplete. The inferolateral trunk and its branches were found to supply the cavernous portions of the mentioned cranial nerves. The obtained data make the anatomic basis for neurosurgical operations in the cavernous region.

Adult↗
PubMed2000

Flexible percutaneous pericardioscopy: inherent drawbacks and recent advances.

Pericardioscopy enables endoscopic inspection and aimed biopsy of the parietal and visceral pericardium. To elucidate possible technical modifications contributing to the feasibility, diagnostic value and safety of the procedure, pericardioscopy with an Olympus HYF-1T flexible endoscope was performed in 32 patients (53.1% males, mean age 46.2 +/- 13.1 years) with pericardial effusions. In all patients, the initial step of the procedure was subxiphoid fluoroscopically controlled pericardiocentesis and drainage of the pericardial effusion. An Olympus FB-41ST biopsy forceps was applied for endoscopically guided pericardial biopsies. Standard sampling was used in 22/32 patients (3 to 6 samples/patient) and extensive sampling in 10/32 patients (18 to 20 samples/patient). In additional 12 patients pericardial biopsy was performed without pericardioscopy, under fluoroscopic control. Endoscopic visualization was clearly superior when pericardial effusion was partially replaced with 100 to 300 ml of air (29/32 procedures) in comparison to 3/32 procedures in which the pericardial effusion was replaced with warm normal saline (37 degrees C). In patients with hemorrhagic effusion (12/32), we either repeatedly injected and removed 100 to 150 ml volumes of normal saline (37 degrees C), or postponed pericardioscopy for 2 to 3 days of active drainage. The specificity of endoscopic findings is low and not decisive for the diagnosis. However, pericardioscopy is significantly contributing to the diagnostic value of pericardial biopsy, especially regarding establishing the new diagnosis and etiology of the pericardial disease. Sampling efficiency was also significantly higher for procedures using aimed pericardial biopsy with standard and extensive sampling compared to procedures performed under fluoroscopy: 86.2%, 87.3%, and 43.7%, respectively. No major complications directly related to the procedure were encountered. Minor complications included: short-run ventricular tachycardia (6.3%), pain at the sheath entry site (75%) and transient fever (37.5%). In conclusion, pericardioscopy with Olympus HYF-1T, after air instillation, is a technically complex, but safe procedure that enables excellent visualization and extensive pericardial sampling with improved diagnostic value of pericardial biopsies.

Adult↗
PubMed2000

Pain-related cerebral activation is altered by a distracting cognitive task.

It has previously been suggested that the activity in sensory regions of the brain can be modulated by attentional mechanisms during parallel cognitive processing. To investigate whether such attention-related modulations are present in the processing of pain, the regional cerebral blood flow was measured using [(15)O]butanol and positron emission tomography in conditions involving both pain and parallel cognitive demands. The painful stimulus consisted of the standard cold pressor test and the cognitive task was a computerised perceptual maze test. The activations during the maze test reproduced findings in previous studies of the same cognitive task. The cold pressor test evoked significant activity in the contralateral S1, and bilaterally in the somatosensory association areas (including S2), the ACC and the mid-insula. The activity in the somatosensory association areas and periaqueductal gray/midbrain were significantly modified, i.e. relatively decreased, when the subjects also were performing the maze task. The altered activity was accompanied with significantly lower ratings of pain during the cognitive task. In contrast, lateral orbitofrontal regions showed a relative increase of activity during pain combined with the maze task as compared to only pain, which suggests the possibility of the involvement of frontal cortex in modulation of regions processing pain.

Adult↗
PubMed2000

Thalamic activation in photic myoclonus.

Regional cerebral blood flow (rCBF) during photic myoclonus was studied by means of positron emission tomography in a 51-year-old male patient suffering from MERRF (myoclonic epilepsy with ragged-red fibres). Frequencies of 3 Hz and 5 Hz flash stimulation were used. Both frequencies elicited paroxysmal EEG-abnormalities but only the higher frequency induced generalized myoclonic jerks. We found a left dominated significant increase of rCBF in the thalamus during myoclonus. The thalamic asymmetry was significant when tested with an ROI approach. The myoclonic activity was accompanied by significantly increased activity in the supplementary motor cortex (SMA). Decreases in rCBF were seen in the limbic, temporal and occipital areas during photic stimulation at both flash frequencies, more expressed during myoclonus. The findings observed in this patient indicate a thalamic focus for photic myoclonus in MERRF. We suggest that photic stimulation induced an abnormal discharge in the thalamus, which was fed forwards via thalamo-cortical connections to the precentral motor cortex, to produce the muscle jerks.

Electroencephalography↗
PubMed2000

Tickling expectations: neural processing in anticipation of a sensory stimulus.

Predictions of the near future can optimize the accuracy and speed of sensory processing as well as of behavioral responses. Previous experience and contextual cues are essential elements in the generation of a subjective prediction. Using a blocked fMRI paradigm, we investigated the pattern of neural activation in anticipation of a sensory stimulus and during the processing of the somatosensory stimulus itself. Tickling was chosen as the somatosensory stimulus rather than simple touch in order to increase the probability to get a high degree of anticipation. The location and nature of the stimulus were well defined to the subject. The state of anticipation was initiated by attributing an uncertainty regarding the time of stimulus onset. The network of activation and deactivation during anticipation of the expected stimulus was similar to that engaged during the actual sensory stimulation. The areas that were activated during both states included the contralateral primary sensory cortex, bilateral areas in the inferior parietal lobules, the putative area SII, the right anterior cingulate cortex and areas in the right prefrontal cortex. Similarly, common decreases were observed in areas of sensorimotor cortex located outside the area representing the target of stimulus, i.e., areas that process information which is irrelevant to the attended process. The overlapping pattern of change, during the somatosensory stimulation and the anticipation, furthers the idea that predictions are subserved by a neuronal network similar to that which subserves the processing of actual sensory input. Moreover, this study indicates that activation of primary somatosensory cortex can be obtained without intra-modal sensory input. These findings suggest that anticipation may invoke a tonic top-down regulation of neural activity.

Adult↗
PubMed1999

Initial clinical experience with PerDUCER device: promising new tool in the diagnosis and treatment of pericardial disease.

BACKGROUND: The idea to enter the normal pericardial sac safely was unrealistic until recently. The development of a novel instrument (PerDUCER pericardial access device) for percutaneous access to the pericardium could potentially have a significant impact, not only on patients with pericardial diseases but even more, or primarily, on diagnosis and treatment of myocardial and coronary disease and arrhythmias. HYPOTHESIS: The overall objective of the present study was to evaluate the feasibility and safety of the percutaneous pericardial access with PerDUCER in patients with pericardial disease, and to analyze our initial experience with this new technique, with particular emphasis on sequential procedural steps. METHODS: The device was studied in five patients with pericardial disease (two men, mean age 50.4 years, range 30-68, four with normal body mass index). The procedure consists of two distinct techniques: (1) access to the mediastinal space, and (2) pericardial capture, puncture, and insertion of the guidewire. Access to the mediastinal space includes the introduction of a blunt cannula, a 0.038 guidewire, a dilator-introducer sheath set, and insertion of the PerDUCER device. Key points of the PerDUCER procedure are as follows: introduction of the blunt cannula without resistance, placement of the dilator-introducer sheath at the upper third of the heart, systolic movements of the PerDUCER device, successful vacuum and capture of pericardium, puncture and introduction of the intrapericardial guidewire. RESULTS: Access to the mediastinal space was accomplished in four of five patients, as were pericardial capture and probably puncture. However, despite numerous successful captures and probably punctures of pericardium, we were not able to confirm introduction of the intrapericardial guidewire into the pericardial cavity in any of our patients (0/5). The procedure was very well tolerated in all patients (5/5). No major complications developed during the procedure, bearing in mind that the intrapericardial placement of the guidewire was not achieved. Minor complications included pain at the dilator-introducer sheath entry site (5/5) and mild transient fever (2/5). CONCLUSIONS: According to the present experience, we believe that, with minor modifications, the PerDUCER device could be successfully implemented for pericardial entry in patients with pericardial disease. Further studies are needed to evaluate the feasibility and safety of this new instrument in patients with a normal pericardium. This could open a most exciting spectrum of possible implementations of the device in the future.

Adult↗
PubMed1999

A PET activation study of dynamic mechanical allodynia in patients with mononeuropathy.

The objective of this study was to investigate the central processing of dynamic mechanical allodynia in patients with mononeuropathy. Regional cerebral blood flow, as an indicator of neuronal activity, was measured with positron emission tomography. Paired comparisons were made between three different states; rest, allodynia during brushing the painful skin area, and brushing of the homologous contralateral area. Bilateral activations were observed in the primary somatosensory cortex (S1) and the secondary somatosensory cortex (S2) during allodynia compared to rest. The S1 activation contralateral to the site of the stimulus was more expressed during allodynia than during innocuous touch. Significant activations of the contralateral posterior parietal cortex, the periaqueductal gray (PAG), the thalamus bilaterally and motor areas were also observed in the allodynic state compared to both non-allodynic states. In the anterior cingulate cortex (ACC) there was only a suggested activation when the allodynic state was compared with the non-allodynic states. In order to account for the individual variability in the intensity of allodynia and ongoing spontaneous pain, rCBF was regressed on the individually reported pain intensity, and significant covariations were observed in the ACC and the right anterior insula. Significantly decreased regional blood flow was observed bilaterally in the medial and lateral temporal lobe as well as in the occipital and posterior cingulate cortices when the allodynic state was compared to the non-painful conditions. This finding is consistent with previous studies suggesting attentional modulation and a central coping strategy for known and expected painful stimuli. Involvement of the medial pain system has previously been reported in patients with mononeuropathy during ongoing spontaneous pain. This study reveals a bilateral activation of the lateral pain system as well as involvement of the medial pain system during dynamic mechanical allodynia in patients with mononeuropathy.

Adult↗
PubMed1997

Corridor procedure--surgical option for treatment of chronic atrial fibrillation in patients undergoing mitral valve replacement.

The aim of this study was to determine the effectiveness of the 'corridor' procedure when added to mitral valve replacement in restoring and maintaining sinus rhythm in patients with chronic atrial fibrillation resulting from rheumatic mitral valve disease. Twenty-two patients with rheumatic mitral valve disease and chronic atrial fibrillation with fast, irregular ventricular response were divided into two groups. In the first group (n = 12), mitral valve replacement was combined with sinus node-AV node isolation ('corridor'): in the second, control group (n = 10), mitral valve replacement was performed through the left atriotomy. The effectiveness of the 'corridor' procedure on heart rhythm was analysed by: (i) 24-h Holter monitoring performed before and during 72 h after surgery, at hospital discharge, and 2 months later; and (ii) postoperative electrophysiological studies using temporary epicardial wires on each isolated atrial compartment. Immediately after surgery and in the following 2 months, heart rate variability analysis showed significantly lower hourly ventricular rates and rate variations in the 'corridor' group compared with those of the control group (P < 0.01). A significant difference was also found when comparing postoperative to preoperative findings in the corridor group (P < 0.05). In the control group, however, no significant differences (P > 0.05) were found concerning pre- and postoperative ventricular rate variations. At hospital discharge, nine of 12 patients with 'corridor' procedure were in sinus rhythm. Control patients remained in atrial fibrillation with irregular ventricular rate. The 'corridor' procedure, when added to mitral valve replacement, prolonged surgery, but led to restoration and long-term maintenance of sinus rhythm in 75% of patients with chronic atrial fibrillation and rheumatic mitral valve disease.

Adult↗
PubMed1993

Control of ventricular rate by interatrial septal incision and crista terminalis myotomy in the patients with atrial fibrillation undergoing mitral valve replacement.

The aim of the study was to analyze the effect of surgical moderation of conduction from the atrium to the atrio-ventricular (AV) node on ventricular response in 30 patients with atrial fibrillation (AF) undergoing mitral valve replacement (MVR). Besides the usual diagnostics, echocardiographic evaluation of the size of the left atrium was performed in all patients, as a parameter of stability of rhythm conversion by drugs. Surgical treatment was applied exclusively in cases where, judging by these parameters, there was little chance for drug treatment to be effective. All patients (mean age 50 years) had severe mitral valve disease (NYHA III and IV), chronic AF and irregular ventricular rate, and underwent mitral valve replacement with mechanical valve. The patients were divided into three groups of ten patients each. In group I: MVR was combined with interatrial septal incision (IASI) to study the effect of the moderation of conduction from the interatrial septum to the AV node; in group II: after MVR, IASI was combined with crista terminalis myotomy (CTM) to study the additional effect of the moderation of conduction along the crista terminalis to the AV node; in group III (control): MVR was performed through left atriotomy, without antiarrhythmic incisions. Ventricular response was studied in two phases: In the immediate postoperative period (up to 7 days), using continuous electrocardiographic (ECG) monitoring, and 2 months postoperatively, using 24 h Holter monitoring with the results compared to a preoperative 24 h recording. Postoperative AF occurred in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1991

Surgical management of extracranial carotid artery aneurysms.

Between 1982 and 1991 we performed eight operations on seven patients with carotid artery aneurysms. Their mean age was 52.8 years (range: 20-67 years). Five aneurysms were atherosclerotic, one was associated with Marfan's syndrome, and two were pseudoaneurysms, one occurring after Dacron patch angioplasty and the other due to tuberculosis. Seven aneurysms were treated electively; one patient underwent an emergency surgical procedure. In one case, the internal carotid artery was ligated. Seven operations were reconstructive. No intraluminal shunt was used. No perioperative deaths occurred. Regressive hemiparesis and ipsilateral Horner's syndrome developed in one patient. The follow-up period ranged from six months to nine and a half years. One patient died of myocardial infarction three months after surgery.

Adult↗
PubMed1990

Comparative tumorigenicity of picene and dibenz[a,h]anthracene in the mouse.

The carcinogenic activity of the two polycyclic aromatic hydrocarbons (PAHs), picene (benzo[a]chrysene) and dibenz[a,h]anthracene (DBA), was determined in NMRI mice by five different experimental protocols in order to find out if picene is a carcinogen as predicted by recent quantum mechanical calculations in contrast to earlier observations which could not confirm any carcinogenic activity of picene. Single s.c. treatment of adult mice with picene or DBA (308 nmol/animal, each) led to the formation of fibrosarcomas in 63.3% of treated animals regardless of the PAH used. Chronic epicutaneous application of both PAHs (total dose 1.36 mumol) to the back of mice resulted in the development of papillomas with a tumor rate of 22% in the case of picene and of 32% in the case of DBA. When newborn mice were s.c. treated once on day 2 of their life with each of the two PAHs (400 nmol/animal), 27.8% of treated animals developed lung adenomas after 40 weeks in the case of picene compared to 92.1% in the case of DBA. Histopathological examination of the tumors in the three experimental models revealed no difference in the type of tumor between picene and DBA. Epicutaneous application of both PAHs (600 nmol/animal) followed by chronic treatment with 12-O-tetradecanoyl-phorbol-13-acetate for 24 weeks led to the formation of papillomas in 93% of animals treated with DBA while picene showed no tumorigenic activity at all. Initiation of tumorigenesis in the two-stage tumor model with 7,12-dimethylbenz[a]anthracene (1 mumol/animal) and chronic treatment with picene (total dose 4.8 mumol) for 24 weeks was equally ineffective in producing tumors in NMRI mice. This rare biological property of picene, which is a complete carcinogen, yet at most a very weak tumor initiator, is explained in terms of its inefficient biotransformation to mutagenic and carcinogenic metabolites as compared to the strong tumor initiator DBA.

Animals↗
PubMed1988

Microsomal metabolism of picene.

Picene, a polycyclic aromatic hydrocarbon (PAH) of environmental relevance has recently been predicted to be carcinogenic, based on quantum mechanical calculation, although in several animal studies no carcinogenicity could be detected. In order to find out if the metabolism of this PAH can provide an explanation for its lack of carcinogenicity, picene was incubated with the hepatic microsomal fraction of Sprague-Dawley rats, which had been pretreated with Aroclor 1254. Sixteen ethyl acetate-extractable metabolites could be separated by reversed-phase high-performance liquid chromatography. Comparison of the chromatographic behavior and the UV and mass spectral properties of the metabolites with those of synthetic derivatives of picene allowed the identification of trans-1,2-, -3,4-, -5,6-dihydrodiol as well as 2- and 4-phenol as microsomal metabolites of picene. At a substrate concentration of 2.7 microM and an amount of 68 micrograms microsomal protein per ml incubation volume, 4-picenol was the main microsomal metabolite with 32.2% of total metabolic conversion, followed by the 1,2-(bay-region)dihydrodiol with 16.7%, the 3,4-(M-region)dihydrodiol with 15.9%, 2-picenol with 9.1% and the 5,6-(K-region)dihydrodiol with 1.6%. In this respect the metabolism of picene is not significantly different from that of the carcinogenic PAH benzo[a]pyrene and dibenz[a,h]anthracene. The M-region dihydrodiols, potential precursors of electrophilically reactive dihydrodiol bay-region epoxides, are formed from all three PAHs at 11-16% of total metabolic conversion. From the 2.8- to 4.4-fold lower amounts of polar and water-soluble metabolites of picene as compared to dibenz[a,h]anthracene and benzo[a]pyrene it is deduced that dihydrodiol epoxides are generated from picene to a much smaller extent than from the two carcinogenic PAHs. The lacking carcinogenicity of picene could therefore result from the inability of microsomal enzymes to transform its M-region dihydrodiol to dihydrodiol bay-region epoxides in amounts necessary to initiate carcinogenesis.

Animals↗
PubMedDate not supplied

Fractures of the clavicle and injuries of the sub-clavian artery. Report of 10 cases.

During four years, the authors have observed ten lesions of the sub-clavian artery associated with a fracture of the clavicle. The clinical picture in one case out of two was that of an acute ischemia of the upper limb. The surgical repair has been performed in 8 cases. The thoracic approach was necessary three times. The clavicle was resected in most cases. The prognosis of these lesions depends on the rapidity of their recognition, and of their treatment, and on the fact whether the brachial plexus is involved or not

Accidents, Traffic↗
PubMedDate not supplied

Clinical and functional evaluation of the Carbomedics Prosthetic Heart Valve in the mitral position. Preliminary results.

The Carbomedics Prosthetic Heart Valve is a new bileaflet pyrolite carbon prosthesis. This paper reports the preliminary results in 40 patients who underwent mitral valve replacement (MVR) using the Carbomedics Valve in 1988. The operative mortality rate was 5% and the early results have been encouraging, with no valve related complications observed in the first post-operative year.

Adult↗
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↗