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S Rokas

Publications and source records attributed to S Rokas.

16 recordsLinked to original sources
PubMed2001

Atrioventricular node modification in patients with chronic atrial fibrillation: role of morphology of RR interval variation.

BACKGROUND: This study evaluates the role of RR interval distribution pattern as an outcome predictor of radiofrequency (RF) modification of atrioventricular (AV) node in chronic atrial fibrillation (AF) and attempts to elucidate the likely mechanism of rate control. METHODS AND RESULTS: Sixty-five patients with chronic AF underwent AV node modification. The RR interval distribution pattern was derived from 24-hour ECG recordings obtained before and after the procedure. The preablation pattern was bimodal (B) in 36 patients (55%) and unimodal (U) in 29 patients (45%). After the modification procedure, the B pattern shifted to U (78%) or became modified B (22%). The mean number of RF pulses delivered and the fluoroscopy time were n=8+/-5 and 24+/-11 minutes, respectively, in patients with B pattern versus n=18+/-7 and 45+/-17 minutes in patients with U pattern (P<0.001 for both). The location of successful ablation was posteroseptal and lower midseptal in 26 patients (81%) with B pattern versus 2 (13%) with U pattern (P<0.001). Mean and maximal ventricular rates and heart rate at peak exercise were reduced after the procedure in both groups (P<0.001 for all). Long-term success rate, AV block incidence, and pacemaker implantation rate were 89%, 0%, and 8%, respectively, in patients with B pattern versus 52% (P<0.001), 21% (P=0.006), and 48% (P<0.001) in patients with U pattern. CONCLUSIONS: RF modification of the AV node is expected to be more effective, safe, and expeditious in patients with chronic AF and B RR interval distribution pattern. Posterior atrionodal input ablation may be the prevailing mechanism of rate control in these patients, whereas U-pattern patients may benefit from partial injury to the AV node.

Adult↗
PubMed1999

A noninvasive method for the detection of dual atrioventricular node physiology in chronic atrial fibrillation.

Considering the electrophysiologic study as a reference, the RR interval distribution analysis is a sensitive (88%) and specific (80%) noninvasive method for detecting dual atrioventricular (AV) node physiology. This method may prove useful in selecting patients with atrial fibrillation who are considered appropriate candidates for radiofrequency modification of AV nodal conduction as opposed to AV nodal ablation.

Aged↗
PubMed1997

Aneurysm of the mitral-aortic intervalvular fibrosa as a rare cause of angina pectoris: angiographic demonstration.

Aneurysms of the mitral-aortic interventricular fibrosa (MAIF) are exceptionally rare complications, commonly following aortic valve endocarditis. This report describes the angiographic findings of such an aneurysm, in a patient who developed an uncommon symptomatology of unstable angina pectoris, caused by the aneurysm's expansion against the coronary arteries. Surgical treatment is also discussed.

Aged↗
PubMed1997

Contraction-excitation feedback in human atrial fibrillation.

BACKGROUND: Contraction-excitation feedback, that is, electrophysiologic changes that are caused or preceded by mechanical changes of the myocardium, has been extensively studied in the ventricles. The role of contraction-excitation feedback in the atria, and more particularly in the genesis and maintenance of atrial fibrillation, has been less adequately investigated. HYPOTHESIS: The aim of the present study was to determine whether increased right atrial pressure (RAP) facilitates the induction of atrial fibrillation (AF) in patients with a history of lone AF. METHODS: Sixteen patients with a history of paroxysmal AF but without structural heart disease were included in the study. All patients underwent electrophysiologic study at both a lower (3.1 +/- 2.0 mmHg) and (in 13 cases) a higher (6.4 +/- 2.5 mmHg) RAP. "Higher" was considered the pressure following rapid (in about 30 min) intravenous administration of normal saline or before the administration of a diuretic. RESULTS: Rapid atrial pacing induced AF in 19 of 29 attempts. At a lower pressure, rapid pacing induced brief (3 s to 3 min) AF in 3 of 16 patients, long-lasting (> 3 min) AF in 3 of 16 patients, and no AF in 10 of 16 patients. At a higher pressure, brief AF was induced in 3 of 10 patients in whom no AF could be induced at a lower pressure, and long-lasting AF in 10 patients in whom either brief AF (3 cases) or no AF (7 cases) was induced at a lower pressure. In 11 patients, in whom Wenckebach periodicity was determined at both higher and lower pressure, the critical cycle length at which atrioventricular block appeared was significantly (p < 0.001, paired t-test) longer (349.1 +/- 44.4 ms, i.e., +15.5 +/- 11.3 ms) at higher than at lower atrial pressure (333.6 +/- 41.0 ms). In nine patients, in whom Wenckebach periodicity was determined and two rhythms occurred at different pressures, the critical cycle length was 332.2 +/- 45.8 ms when associated with sinus rhythm, and significantly (p < 0.01) longer (344.4 +/- 48.0 ms, i.e., +12.2 +/- 8.3 ms) when associated with induction of AF. CONCLUSION: In patients with lone atrial fibrillation, modest increases in atrial pressure may facilitate the induction of atrial fibrillation.

Atrial Fibrillation↗
PubMed1996

Electrophysiologic abnormalities of cardiac function in progressive systemic sclerosis.

The heart has been generally recognized as a target organ in progressive systemic sclerosis. Noninvasive studies have assessed the incidence and prognostic importance of cardiac arrhythmias in these patients. However, detailed exploration of the function of impulse formation and the conduction system of the heart in these patients has never been reported. Therefore, invasive electrophysiologic studies were performed in 30 patients with systemic sclerosis, all of whom had neither obvious cardiac involvement nor cardiac arrhythmias, and in 32 subjects with no evidence of heart disease, who served as a control group. Corrected sinus node recovery time in patients with systemic sclerosis was significantly longer (P < .001) than in the control group, as was the HV interval (P < .05). Of the 30 patients with systemic sclerosis, 10 had an HV interval of 60 ms or longer. In four patients with systemic sclerosis, the recorded AH interval exceeded 125 ms. The intra-atrial conduction time tended to increase to a significant degree (P < .05) in patients with systemic sclerosis. The interatrial conduction time was much longer (P < .001), and the maximal conduction delay to the atrioventricular junction and to the distal coronary sinus was much greater in the patients with systemic sclerosis than in the control group (P < .001 for both). Supraventricular tachyarrhythmias were induced in 15 patients with systemic sclerosis versus 3 control group subjects (P < .001). With respect to corrected sinus node recovery time, AH and HV intervals, atrial vulnerability, and ventricular tachycardia, 3 of the 30 patients with systemic sclerosis had abnormal findings in one of these parameters and 14 had abnormalities in more than one. These results suggest that a broad spectrum of electrophysiologic abnormalities is present in patients with systemic sclerosis, which can be revealed only by invasive studies. Furthermore, this study provides additional support for the hypothesis that diffuse myocardial involvement is characteristic of scleroderma patients, since a number of these patients showed more than one electrophysiologic defect.

Adolescent↗
PubMed1992

Proarrhythmic effects of reactive hypoglycemia.

A patient with refractory atrioventricular nodal reentry tachycardia is reported in whom it was possible to document that reactive hypoglycemia was the trigger for aggravation of arrhythmia. Over a period of 6 years, a series of electrophysiological studies revealed that, when the patient was in a hypoglycemic state, initiation of tachycardia was easy and most importantly that tachycardla termination by extra-stimulus pacing always failed. Furthermore, atrial fibrillation was inducible or spontaneously occurred only when the blood glucose level was reduced by IV insulin administration.

Blood Glucose↗
PubMed1991

Chronic atrial fibrillation and incessant ventricular tachycardia treated with a single transcatheter ablation.

We present a unique patient with a 12-year history of chronic atrial fibrillation resistant to external direct current shocks associated with incessant ventricular tachycardia. Both arrhythmias were treated with a single shock delivered through a catheter at the atrioventricular junction. The other unusual feature is that sinus rhythm has been maintained in a follow-up of 6 months after the intervention.

Atrial Fibrillation↗
PubMed1990

Electrophysiologic studies of the heart in patients with rheumatoid arthritis.

We investigated the electrophysiological properties of the heart in patients with definite or classical rheumatoid arthritis using programmed electrical stimulation techniques. Twelve patients with rheumatoid arthritis and without evidence of organic heart disease or arrhythmia detectable with serial electrocardiograms and 24-hour ambulatory electrocardiographic monitoring were compared with 12 control subjects. Stimulation was performed from the high right atrium and right ventricular apex at a drive cycle length of 600 msec and the recording sites included high right atrium, atrioventricular junction and distal coronary sinus. There was no statistically significant difference in the corrected sinus node recovery time between the study and control group of patients. Similarly, no differences from normal were found in the AH and HV intervals or in the atrial and ventricular refractoriness, whereas the atrioventricular nodal effective refractory period was higher in patients with rheumatoid arthritis, compared with the control group (338 +/- 38 vs 286 +/- 29, P less than 0.02). The atrial conduction time during basic cycle length had a tendency to increase from high right atrium to atrioventricular junction in the study group and reached statistical significance from high right atrium to coronary sinus (92 +/- 15 vs 74 +/- 14, P less than 0.05). Electrophysiologic differences between the study and control patients also included a greater increase in maximal intraatrial (40 +/- 13 vs 27 +/- 16, P less than 0.05) and interatrial conduction delay (54 +/- 16 vs 31 +/- 12, P less than 0.01) of early premature stimuli in patients with rheumatoid arthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cardiac involvement in postnatal rubella.

Two cases of rubella myocarditis are reported: a 6-year-old boy who developed a complete, distal to His, atrioventricular block, during the third day of illness; and a 12-year-old boy who developed myocarditis with congestive heart failure 20 days following rubella infection. Although permanent pacing was required in the first patient, six years later he showed a normal growth and maintained normal activity. The second patient has deteriorated markedly and 6 months after the initial illness he had severe heart failure. It should be noted that myocarditis with abnormalities of the conduction system or congestive heart failure may be a complication to postnatal rubella.

Child↗
PubMed1989

Valvuloplasty with large trefoil balloons for the treatment of congenital pulmonary stenosis.

Percutaneous balloon valvuloplasty was performed in 16 children, 1 1/2 to 14 years old, with congenital pulmonary stenosis with teh use or trefoil balloons. These balloons, which consist of 3 identical angioplasty balloons, do not interrupt completely the blood flow during inflation. The size of the trefoil balloons used was 30 to 50% larger than the valve anulus. A obtain an effective pulmonary valvuloplasty in two patients with large valve anulus. The mean prevalvuloplasty systolic gradient fo 78.2 +/- 28.9 mmHg (range 40 to 140 mmHg) was reduced to 20.3 +/- 5.7 (range 10 to 30 mmHg) after valvuloplasty. No patient developed significant hypotension or bradycardia or other complications as a result of the procedure. The findings demonstrate that percutaneous balloon valvuloplasty with oversized trefoil balloons effectively treated congenital pulmonary stenosis without complications in the cases studied. The use of large trefoil instead of single balloons of a similar diameter is advantageous since they cause no significant compromise of the cardiac output during valvuloplasty.

Adolescent↗
PubMed1985

Identification of pacemaker dependent patients by serial decremental rate inhibition.

In a study of the concept of pacemaker dependence, 86 patients who had permanent ventricular demand (VVI) pacemakers implanted for more than six months and were in predominantly paced rhythm underwent repeated interruption of pacing both abruptly and after gradual reduction of paced rate. Non-invasive pace slowing was accomplished by timed inhibiting pulses applied to the chest wall. The results identified a small group (A) of patients, 8% of those tested, who consistently failed to develop an adequate escape rhythm and may thus be considered highly pacing dependent. A second group B, 26%, developed an adequate intrinsic rhythm with serial decremental rate inhibition (SDRI) but suffered symptoms with abrupt complete inhibition (ACI). The remaining 66%, group C, developed no symptoms in any test. Analysis of clinical pre-test data showed that syncope, atrioventricular block and a low rate prior to implant, and a long duration of pacing were associated with a higher degree of pacing dependence, but were not reliably predictive. The clinical significance and value of the results are discussed. We conclude that SDRI is a reliable test for the high degree of pacemaker dependence and can be helpful especially in planning a procedure which may involve interruption of pacing.

Adult↗
PubMed1981

Cefotaxime: clinical and bacteriologic evaluation.

Cefotaxime, a new parenteral beta-lactamase-resistant cephalosporin, was tested against 78 cephalothin-resistant clinical isolates of Enterobacteriaceae and Pseudomonas species. The anti-bacterial activity of the drug was compared with activities of cefazolin and cefuroxime and was found considerably more active. Most of the cephalothin-resistant strains were resistant to cephazin, too. The antipseudomonal activity of cefotaxime was found limited. The drug was found effective against 23 infections in hospitalized patients with only one clinical failure and two colonizations with cefotaxime-resistant bacteria. Cephalosporinases hydrolyzing cefotaxime were detected in two cefotaxime-resistant strains. Also, beta-lactamases hydrolyzing cefoxitin and cefuroxime were produced by the cefotaxime-resistant isolates studied.

Aged↗
PubMedDate not supplied

Cardiac performance in collagen diseases estimated by non-invasive methods.

The myocardial performance was studied in 3 collagen diseases, i.e. rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and progressive systemic sclerosis (PSS). Sixteen patients with SLE, 12 with RA and 11 with PSS were examined, measuring the systolic time intervals from the first derivative of the carotid pulse in all cases. The ejection fraction (EF), was evaluated in 33 patients using radionuclide left ventricular angiography. The systolic time intervals were compared to those of 103 normal persons and the EF to that of 22 normal controls. In the SLE group the pre-ejection period was significantly shorter, while the ejection period was longer than normally expected. In the same group, the EF was significantly higher that the EF of the control group. These differences could not be related to age, blood pressure, disease duration, coronary risk factors, heart rate or blood values. Most findings in the RA group tended to be opposite to those of SLE. It is concluded that in SLE before any direct involvement of the heart the systolic time intervals and the EF present features similar to those of increased cardiac performance.

Adult↗
PubMedDate not supplied

Paget's bone disease, anaemia and vitiligo: a case report.

The coexistence of Paget's bone disease, pernicious anaemia and vitiligo is very rare. The pathogenesis of Paget's bone disease remains still unknown. We report here a patient having these three entities simultaneously and we suggest that some cases of Paget's bone disease be due to autoimmunity.

Anemia, Pernicious↗