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P Pedroni

Publications and source records attributed to P Pedroni.

At least 37 records · Page 2Linked to original sources
PubMed1989

Reliability of transesophageal pacing in the assessment of sinus node function in patients with sick sinus syndrome.

The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node function in patients with sick sinus syndrome (SSS). In 17 patients with SSS (study group) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and, 24 hours later, by transesophageal pacing. In another group of 17 patients with SSS (control group), we compared the results obtained by two endocavitary studies. In "study group", sinus cycle length (SCL) and corrected sinus node recovery time (CSRT) did not show significant differences between the two studies both in the basal state and after autonomic blockade, whereas sinoatrial conduction time (SACT) was more prolonged during esophageal pacing (P less than 0.01). In "control group", sinus node measures did not show significant differences between the two studies. In the "study group," the following coefficients of correlation were obtained in the basal state; SCL, r = 0.65, CSRT, r = 0.57, SACT, r = 0.52 and after autonomic blockade: SCL, r = 0.95, CSRT, r = 0.62 and SACT, r = 0.53. In the basal state, the correlation for SCL and CSRT between the two studies was lower in the "study group" than in the "control group" (P less than 0.05), whereas after autonomic blockade the correlation for sinus node measures did not show significant differences between the two groups of patients. These data suggest that transesophageal study influences the autonomic tone regulating the sinus node; however, it is not responsible for important variations in sinus node measures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Cloning of a novel pilin-like gene from Bordetella pertussis: homology to the fim2 gene.

A search for pilin genes in a Bordetella pertussis (Bp) genomic library has led to the identification of several clones which hybridize to synthetic oligonucleotides with sequences derived from amino acid sequences of Bp fimbrial subunits. One of these clones (corresponding to a gene we have named fimX) contains an open reading frame encoding a protein with a molecular weight of about 20 kD and a sequence similar but not identical to the fimbrial subunit fim2 and to other fimbrial protein sequences. In this communication we present the cloning and nucleotide sequence of the fimX gene and its homology to the fim2 gene. A genomic analysis on the positional relationship between the two genes is also presented.

Amino Acid Sequence↗
PubMed1988

Bordetella pertussis pilin and pilin-like genes.

Bordetella pertussis fimbriae, which mediate the adherence of the microorganism to the epithelium of the respiratory tract, elicit a protective immunogenic response which could be taken advantage of for the creation of an acellular vaccine against pertussis. A few of the fimbrial proteins have been partially characterized by immunological means which recently the cloning and characterization of pilin and pilin-like genes are allowing us to study their structure, regulation of expression during the infectious cycle of Bordetella pertussis, and the basis for antigenic variation. In this communication we will review recent data on Bordetella pertussis pilin and pilin-like genes and their products, with particular emphasis on data most relevant to the design of an acellular vaccine.

Amino Acid Sequence↗
PubMed1988

[Usefulness of transesophageal stimulation in the evaluation of sinus node function in patients with sick sinus syndrome].

The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node function, besides Wenckebach point, in patients with sick sinus syndrome. In 17 patients with sino-atrial disease (group I) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and 24 hours later, by transesophageal pacing. In another group of 17 patients with sino-atrial disease (control group) we compared the results obtained from two endocavitary studies. In group I, sinus cycle length and corrected sinus recovery time did not show significant differences between the two studies either the basal state or after autonomic blockade, whereas sino-atrial conduction time was more prolonged during esophageal pacing (P less than 0.01). In the control group, sinus node measures did not show significant differences between the two studies. In group I, the following coefficients of correlation were obtained: A) in the basal state sinus cycle length, r = 0.65, corrected sinus recovery time, r = 0.57, sinoatrial conduction time, r = 0.52; B) after autonomic blockade sinus cycle length, r = 0.95, corrected sinus recovery time, r = 0.62 and sino-atrial conduction time, r = 0.53. In the basal state, the correlation for sinus cycle length and corrected sinus recovery time between the two studies was lower in the "study group" than in the "control group" (P less than 0.05). However, after autonomic blockade the correlation for sinus node measures did not show any significant differences between the two groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Effect of alpha 1 adrenergic stimulation on myocardial relaxation].

The aim of the present study was to elucidate which was the effect of alpha 1 adrenergic stimulation on myocardial relaxation. Experiments were performed in cat papillary muscles contracting isometrically at 12 beats/min. The effect of phenylephrine (P) in the presence of propranolol (10(-6)M) on myocardial relaxation was compared with that produced by a similar increase in myocardial contractility (+T) elicited by increasing extracellular calcium (Ca2+). An increase of 40% in maximal velocity of contraction (+T) produced by P and Ca2+ elicited in both cases a proportional increase in maximal velocity of relaxation (-T). Therefore the +T/-T ratio remained unchanged. At this contractility level relaxation time (Rt) and time to half relaxation (t1/2) were slight by significantly prolonged by P and not changed by Ca2+. When contractility was increased by approximately 200%, both, P and Ca2+ increased by a less extent -T. Consequently +T/-T augmented from 1.21 +/- 0.04 to 1.73 +/- 0.09 (48.3 +/- 9.5%) with P, and from 1.37 +/- 0.04 to 1.77 +/- 0.15 (31 +/- 12%) with Ca2+. Rt was also significantly increased by both interventions: 21.5 +/- 8.8% (Ca2+) and 24.2 +/- 2.68% (P), whereas t1/2 was significantly increased by P from 215 +/- 11 msec to 282 +/- 12 msec (33 +/- 5.8%) but did not change with Ca2+. Prazosin (10(-6)M) antagonized the effects on contractility and relaxation produced by P. The present results thus indicate that the positive inotropic effect of alpha 1 adrenergic stimulation may be characterized by a prolongation of the early relaxation phase, that was not mimicked by a similar increase in myocardial contractility elicited by increasing extracellular calcium.

Animals↗
PubMed1987

[Inhibitory effect of propranolol on myocardial relaxation not mediated by beta blockade].

The effect of d- and d,l-propranolol (10(-5)M) on myocardial relaxation was studied in the isolated cat heart beating at constant rate and perfused at constant coronary flow. Infusion of d,l-propranolol 10(-5)M produced a significant decrease in maximal velocity of contraction (+T) of 48 +/- 1.5%, P less than 0.05, and a proportionally greater decrease in maximal velocity of relaxation (-T) of 58 +/- 2%, with a significant increase in the ratio between both maximal velocities (+T/-T) of 28.4 +/- 6.2% (from 1.35 +/- 0.03 to 1.74 0.09). The time constant of tension decline computed from the time of -T (Tau) was significantly prolonged by 64 +/- 17.5% (from 38 +/- 1.4 to 61 +/- 6 msec) (P less than 0.05). Similar results were obtained with d-propranolol (10(-5)M). A decrease in +T of 52.2 +/- 4.1% elicited by perfusion with low calcium (0.05 mM) also produced a slight increase in +T/-T and Tau by 11 +/- 4.5% and 27 +/- 6% respectively, P less than 0.05). These increases were, however, lower than those produced by both d,l- and d-propranolol (P less than 0.05). The effect of low calcium on +T, +T/-T and Tau were fully reversible, whereas the complete reversal by calcium of the negative inotropic effect of d- and d,l-propranolol did not reverse the significant decrease in -T and increase in +T/-T, and Tau elicited by the drug. Similar results were obtained in catecholamine depleted hearts. d-propranolol (10(-5)M) did not affect the calcium sensitivity of the chemically skinned cat right ventricular trabeculae. The calcium uptake of cat cardiac sarcoplasmic reticulum was significantly inhibited by d-propranolol from a concentration of 3 X 10(-4) M. The results suggest that propranolol 10(-5)M has an antirelaxant effect, not mediated by its negative inotropic action and independent of its beta blocking action. This antirelaxant effect might be mediated by the SR calcium uptake inhibition produced by the drug and might be a possible mechanism by which high concentrations of these agents negatively affect myocardial contractility.

Animals↗
PubMed1985

Renal hypertension impairs inotropic isoproterenol effect without beta-receptor changes.

Experiments were performed in male Wistar rats with renovascular hypertension (167 +/- 4.2 mmHg) produced by clipping the renal artery for a 3-wk period (2-kidney, 1-clip Goldblatt). The results were compared with those obtained in age-matched normotensive controls. Hypertension of 3-wk duration elicited a significant increase in ventricular weight (1.01 +/- 0.02 g) with respect to the controls (0.82 +/- 0.01 g) but had no significant effect on body weight. The inotropic responsiveness to beta-adrenergic stimulation was diminished in papillary muscles from renal hypertensive rats: the maximum increase in the maximal rate of rise of tension produced by isoproterenol was 27.39 +/- 5.4 and 11.77 +/- 2.91 g X mm-2 X s-1 (P less than 0.05) in control and hypertensive animals, respectively. Similar results were obtained when the estimated maximal velocity of shortening of the contractile element (Vmax) was used to assess myocardial contractility. The inotropic response to CaCl2 was also significantly depressed in the 2-kidney, 1-clip rats. However, the relaxant and the chronotropic responses to isoproterenol were not significantly modified in the Goldblatt rats. Assays of beta-adrenergic receptors to l-[3H]dihydroalprenolol binding, showed no significant changes in the number (expressed per mg of membrane protein) or in the affinity of the beta-receptors. These results suggest that at an early stage of the renal hypertensive model the impaired inotropic response to isoproterenol is not mediated by an alteration of the beta-receptors and should be searched at a postreceptor adenyl cyclase level.

Animals↗
PubMed1981

Double atrial tachycardia with functional atrial dissociation.

A 57-year-old man with hypertensive and coronary heart disease and bradycardia-tachycardia syndrome suffered from paroxysmal palpitations, during which ECG showed a low atrial tachycardia at a rate of 150-200 beats/min with Wenckebach A-V block. During electrophysiological study an episode of atrial tachycardia appeared, characterized by: - atrial potentials in the high atrial electrocardiogram with regular cycle length (500-530 msec); - atrial potentials in the His bundle electrocardiogram with cycle length (570-580 msec), interrupted by premature atrial beats with coupling interval of 420-480 msec and with an atriogram of identical morphology. A-V conduction showed Wenckebach A-V block. After the cycles of 570-580 msec the low atrial potentials were simultaneous or preceded or followed the high atrial potentials by 10-20 msec. After the cycles of 420-480 msec the low atrial potentials preceded the high ones by 40-70 msec. Then, high atrial tachycardia abruptly stopped and the low atrial tachycardia only persisted with the same cycle length (570-580 msec); the high atrium was captured by the low atrial impulses with a low atrium - high atrium interval of 70 msec. These findings suggest that during the first part of tachycardia a conduction neither from high to low atrium, nor from low to high atrium can be possible. It is therefore a particular case of double atrial tachycardia - to our knowledge never before described in literature - sustained a few seconds because of functional atrial dissociation, induced by refractoriness related to the impulses delivered by the two tachycardia foci. The double atrial tachycardia was not diagnosed in the surface ECG leads. The two foci both appear to be localized at atrial level. The electrophysiological mechanism and the differential diagnosis with tachycardias at different sites are discussed.

Bradycardia↗
PubMed1981

[Paroxysmal supraventricular tachycardias due to re-entry via concealed retrograde atrio-His bypass (author's transl)].

Recently there have been proposed electrophysiologic criteria for the diagnosis of a concealed atrio-His bypass tract in patients with paroxysmal supraventricular tachycardia (PST). In order to verify the reliability of the proposed criteria--among the patients we studied for PST without ventricular preexcitation and in whom retrograde His bundle activation was recorded--we have chosen those with normal anterograde A-V conduction, with constant (or minimal increases) V-A interval during ventricular pacing and with short (less than 50 msec) and constant H2-A2 interval during ventricular premature stimulation. We encountered 15 patients with these electrophysiologic characteristics (37-73 years). H2-A2 interval (measured from the end of the His bundle deflection to the earliest atrial activity) ranged 20-45 msec (mean: 33 msec). The prolongation of S2-A2 interval observed in all patients was always within the S2-H2 tract. The retrograde effective refractory period of the A-V nodal region was always short, but not evaluable in any of the patients since it was shorter than that of ventricular myocardium (14 cases) or of His-Purkinje system (1 case). The S1-H2 interval was measured to evaluate whether during ventricular premature stimulation the retrograde His bundle activation was in fact anticipated. In 14 out of 15 patients this interval varied within a very narrow range: 0-20 msec. For this reason we believe that the differential diagnosis between a concealed atrio-His bypass and an accelerated retrograde A-V conduction can only be made if during electrophysiologic study a tachycardia is induced; in such case the detection of an H-Ae interval identical to H2A2, together with a normal retrograde atrial activation, is indicative of a bypass of the A-V node. A concealed atrio-His bypass tract must be differentiated also by a concealed septal Kent bundle; also in this case we believe that the detection of an H-Ae interval identical to H2-A2 indicates the former type of bypass. We conclude that a concealed atrio-His bypass can be diagnosed only if, besides the electrophysiologic criteria proposed by other authors, there is an H-Ae interval the same as H2A2.

Adult↗
PubMed1981

[Serum lipids in acute myocardial infarction].

The following lipidic fractions were determined in a population of patients with acute myocardial infarction (AMI) and in a control group: total cholesterol, triglycerides, total phospholipids, HDL-cholesterol and HDL-phospholipids. The assays were repeated four times during the hospitalization of the patients admitted for AMI. With respect to total cholesterol, triglycerides and HDL-cholesterol, our findings correlated well with the results published in literature, inasmuch as they confirmed positive interrelation for total cholesterol/AMI and triglycerides/AMI ratios and a negative interrelation for HDL-cholesterol/AMI ratio. During the 20 days following infarction, these three parameters decreased to significantly lower values. The relationship linking total phospholipids and HDL-phospholipids to myocardial infarction has not yet been sufficiently investigated and the few available seem rather contradictory. The results which we have obtained seem to indicate a connection between increased total phospholipids and AMI, whereas HDL-phospholipids do not seem to provide any discriminant indication.

Adult↗
PubMed1980

[The bundle branch block anatomically located in HIS bundle (author's transl)].

Bundle branch block (BBB) patterns are commonly considered to represent conduction block in the corresponding bundle branch. However, several histological and experimental studies demonstrated the possibility of a BBB related to an anatomical lesion within the His bundle. Recently there has been demonstrated, also in clinical setting, the possibility of evaluation whether a left bundle branch block (LBBB) is related to an anatomical within such bundle. For this purpose the selective stimulation of the His bundle has been utilized. A distal simulation of such bundle (which can be evaluated by a stimulus-QRS interval shorter than HV interval) normalizing the QRS complexes compresses an anatomical lesion within the proximal His bundle. Such normalization cannot be attributed to a right septum stimulation since the LBBB pattern should be increased instead of disappearing. The Authors think that an anatomical localization within the His bundle can be evaluated only in LBBB. In fact it is possible that a right bundle branch block pattern, if a septal calcification or fibrosis is present, could be normalized also in the presence of an isoelectric line placed between the artificial stimulus and the QRS complex. There is criticized the concept supported by other Authors that normalization of the QRS complex may be related to a summation effect between the sinusal impulse and that artificially induced. In fact such effect can be easy excluded by analizing the temporal relationship between the ventriculograms registered during His bundle stimulation and the atriograms. The clinical implications of the LBBBs in relation with an anatomical lesion within the His bundle are discussed.

Bundle of His↗
PubMed1978

[Alpha-lipoproteins and viral hepatitis (author's transl)].

The plasma levels of alpha-lipoproteins, triglycerides, cholesterol, bilirubin, ALT and AST were followed serially in a group of 10 patients with acute viral hepatitis. Hypertrygliceridaemia, low level of cholesterol and very low level of alpha band of the lipoproteins were found at the onset of the disease. Alpha-lipoprotein reappeared gradually during the course of the disease and was sensitive indices of improvement of liver function. A negative linear correlation was found between alpha-lipoprotein and total bilirubin and between alpha-lipoprotein and ALT.

Adolescent↗
PubMed1978

[Electrophysiological effects of ajmaline on the human conduction system (author's transl)].

The electrophysiological effects of ajmaline have been investigated using the intracardiac electrograms and the extrastimulus method. The drug was infused intravenously into 21 patients at the dose of 1 mg/Kg. Ajmaline induces:--variable effect on the sinusal cycle length--variable effect on the corrected sinus node recovery time--increase of the atrial effective refractory period (P less than 0.001)--in AV node slowing of conduction (P less than 0.001), a slight prolongation of PRE (P less 0.01) and more marked one of the FRP (P less than 0.001). The His-Purkinje (HV interval) and intraventicular (QRS interval) conduction times are prolonged (P less than 0.001), as well as the RRF of His-Purkinje system. The maxium increase of AH,HV and QRS intervals appears 3 minutes after drug administration; at the 5th minute these intervals have already slightly decreased, then they decrease almost quickly till the 15th minute and more slowly till the 30th minute. The absolute prolongation of the HV and QRS intervals is more marked in the patients in which these intervals are more prolonged during the control study, while the percentage increase is almost equal in the patients with normal HV and QRS interval and in those with prolonged HV and QRS intervals. The electrophysiological properties of the drug are discussed on the basis of the obtained results.

Adult↗
PubMedDate not supplied

[Use of Gated-SPECT with with 99mTC-MIBI in the evaluation of the prognostic significance of ventricular arrhythmias during a stress test].

UNLABELLED: The presence of ventricular complex cardiac arrhythmias in coronary patients, both at rest or during physical exercise, is considered a risk factor for future coronary events or sudden death during long time follow up. The meaning of ventricular complex arrhythmias (VCA) in patients with normal ventricular function and without myocardium ischemia has still not been explained. This study aimed to evaluate if patients with normal ventricular function and no evidence of cardiac ischemia (determined by means of Gated SPECT) who developed VCA during stress test show an increase in cardiac events on later monitoring. PATIENTS AND METHODS: All patients were studied by means of an ergometric exercise test using a standard Bruce protocol and Gated SPECT with Methoxyisobutyl Isonitrile-99mTechnetium (99mTC-MIBI). Sixty-seven (67) patients with normal ventricular function and no evidence of cardiac ischemia were included. RESULTS: 13 patients had VCA and 54 had no ventricular arrhythmias during stress test. During the follow up of 681.3 +/- 469 days, none of the 13 patients had sudden death, angina pectoris or myocardium infarction. CONCLUSIONS: In our sample, the appearance of VCA during stress test in patients without myocardium ischemia and normal ventricular function was not associated with an increase of cardiac events during the monitoring which was carried out.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Left main coronary artery disease. Clinical and angiographic features. A retrospective study regarding two groups of patients with left main coronary artery disease and three-vessel disease.

BACKGROUND: The aim of this study was to assess the ability of clinical and instrumental features to identify patients with left main coronary artery disease (LMCD) compared with a three-vessel coronary artery disease group. METHODS: A cohort of 70 patients with LMCD was matched with another one of 66 patients with three-vessel disease. A history of angina before angiography was similar in both groups; the higher degrees of stable angina and the forms of unstable angina were moderately prevalent in the group with LMCD. RESULTS: In the last subgroup a significantly reduced incidence of previous acute myocardial infarction (AMI) was observed (p < 0.05). The resting electrocardiogram (ECG) showed higher incidence of atrial fibrillation (fa) and left bundle branch block (BBS) in the subjects with LMCD, with a statistic value (p < 0.05). The exercise test performed by a lot of patients appeared equally positive for inducible ischemia in the 2 groups. Significantly higher exercise peak load was achieved by the patients with three-vessel disease (p < 0.05). The coronary angiography showed a prevalence of right dominant circulation in the 2 groups; significantly the collateral circulation was more represented in the subjects with three-vessel disease (p < 0.05). Most patients with LMCD underwent a bypass coronary artery graft surgery (CABG surgery) more frequently than the ones with three-vessel disease (p < 0.01). In the former group the cardiovascular mortality within an average 2-year follow-up proved higher as to the latter group even if without statistic significance. CONCLUSIONS: Nevertheless this retrospective study showed some limitations. Particularly the incidence of clinical and instrumental variables and their capacity to differentiate LMCD patients from those with three-vessel disease were not demonstrated.

Acute Disease↗