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Biomedical subjects

P Rizzon

Publications and source records attributed to P Rizzon.

At least 145 records · Page 8Linked to original sources
PubMed1990

The nature and evolution of ventricular arrhythmias in acute myocardial infarction.

The natural evolution of ventricular arrhythmias complicating a first episode of acute myocardial infarction has been studied in a group of 56 consecutive patients, who were admitted to the Coronary Care Unit within three hours of the onset of symptoms, and in whom drug administration (digitalis, antiarrhythmics, diuretics and heparin) was limited. Ventricular arrhythmias have been evaluated by means of Holter monitoring performed during the first 24 hours, the second 24 hours, the eighth day, the 18th day and two years after discharge when antiarrhythmic drugs has been discontinued for at least five half-lives. The overall incidence and prevalence of ventricular arrhythmias showed a steady and statistically significant reduction from the first to the eighth day, and a not statistically significant increase from the eighth to the 18th day. The latter increase was still present at the two-year follow-up. The one-by-one behaviour analysis of discharged patients delineated three different patterns: patients who presented a steady reduction in ventricular arrhythmias from the first to the 18th day (44%); patients who showed an almost constant incidence of ventricular arrhythmias during all phases of acute myocardial infarction (24%); and patients who presented both a decrease and an increase in their ventricular arrhythmias (31%). The follow-up at two years showed that the majority of patients, especially those discharged in a high Lown class, had the same arrhythmias as at their follow-up on the 18th day. Correlation of ventricular arrhythmias with the extent of the infarcted area demonstrated that only the peak and mean values of lactic dehydrogenase correlated with the severity of ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1990

Clinical use of transoesophageal atrial stimulation in terminating ventricular tachycardia.

This study was performed to evaluate whether transoesophageal atrial pacing could also stop ventricular tachycardias with low rates and no haemodynamic impairment. Prior to resorting to ventricular endocardial pacing, seven male patients, aged between 15 and 73 years, were treated by transoesophageal atrial pacing for 10 spontaneous episodes of sustained ventricular tachycardia at rates between 105 and 160 beats per minute, without haemodynamic impairment. When atrial pacing did not allow ventricular capture, atropine sulphate was administered. Transoesophageal atrial pacing led to ventricular capture in seven episodes, which made overdriving possible, and blocked six episodes of ventricular tachycardia. In no case did transoesophageal atrial pacing lead to an acceleration of ventricular tachycardia or to degeneration into ventricular fibrillation. Transoesophageal atrial pacing can block low-rate sustained ventricular tachycardias (less than or equal to 150 beats per minute). For low-rate sustained ventricular tachycardias without haemodynamic impairment, transoesophageal atrial pacing can thus be used as the method of choice thanks to its good ratio of risk to efficiency.

Adolescent↗
PubMed1990

Errors in measurements of stroke volume for invasive and echo-Doppler evaluations of valvular regurgitant fractions. Clinical evaluation and computer simulation.

The aim of this study was to compare cardiac catheterization (CATH) with 2D echo-Doppler (ED) in clinically evaluating the stroke volumes (SV) needed to calculate aortic and mitral regurgitant fractions (aortic and mitral SV for the ED method, thermodilution and angiographic SV for the CATH). As there is no 'gold standard' for this kind of measurement, only subjects without valvular regurgitation were considered. In these subjects, though the two SV measurements needed to calculate the regurgitant volume should have been identical, there was, in fact a difference due to the systematic and random errors of the methods. We calculated the mean value and the standard deviation of this difference in a series of patients without valvular regurgitation in order to obtain an estimate of both systematic and random errors. In 20 patients studied by ED a difference of 11.9 +/- 16.7 ml was found. In 36 patients studied by cardiac catheterization the difference was 19.6 +/- 20.1 ml. A significant systematic error was found for both ED and the invasive method; The transmitral SV tended to be larger than the aortic and the angiographic SV larger than that obtained by thermodilution. To try to determine the extent to which the random errors could be attributed to the reproducibility of the measurements, we carried out computer simulations. The SVs of 50 000 hypothetical patients were randomly generated and then attributed a random error calculated on the basis of the variability of the CATH (thermodilution 4%, angiography 10%) and the ED measurements (aortic annulus 6%, mitral annulus 18%, mitral time velocity integral 10%, aortic time velocity integral 8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Antiplatelet treatment with ticlopidine in unstable angina. A controlled multicenter clinical trial. The Studio della Ticlopidina nell'Angina Instabile Group.

We conducted a controlled multicenter trial with central randomization and evaluation of events under blind conditions involving 652 patients with unstable angina. Patients were treated either with conventional therapy alone (group C) (n = 338) or with conventional therapy combined with an inhibitor of platelet aggregation, ticlopidine 250 mg b.i.d. (group C + T) (n = 314). Patients were assigned randomly within 48 hours of admission and followed up for 6 months. With the "intention-to-treat" approach, the primary end points, vascular death and nonfatal myocardial infarction, were observed in 13.6% of the patients in group C and in 7.3% of the patients in group C + T, which is a reduction in risk of 46.3% (p = 0.009). Vascular mortality was 4.7% in patients in group C and 2.5% in patients in group C + T, which is a reduction in risk of 46.8% (p = 0.139). The risk of nonfatal myocardial infarction was reduced by 46.1% (p = 0.039), with a frequency of 8.9% in patients in group C and 4.8% in patients in group C + T. New Q wave myocardial infarction occurred with a frequency of 6.8% in patients in group C and 3.8% in patients in group C + T, which is a reduction in risk of 44.1% (p = 0.091). Fatal and nonfatal myocardial infarction was 10.9% in patients in group C and 5.1% in patients in group C + T, which is a reduction in risk of 53.2% (p = 0.006). These findings confirm the importance of platelets in the pathogenesis of unstable angina and the usefulness of antiplatelet treatment for the prevention of cardiovascular events.

Angina Pectoris↗
PubMed1990

[Effects of gallopamil on coronary blood flow and vasomotility].

Using quantitative coronary arteriography, the luminal area was measured in the proximal, middle and distal third of a normal coronary vessel in basal condition and 15 min after 0.005 mg/Kg ic gallopamil (Group 1); 15 min after ic placebo (Group 2); 15 and 30 min after iv gallopamil at a dose of 0.03 mg/Kg (Group 3A) and 0.05 mg/Kg (Group 3B). A significant (p less than 0.001) vasodilation was observed in all segments in Group 1 and only in distal segment (p less than 0.05) in Group 3B. Neither did the heart rate, systolic blood pressure nor the coronary driving pressure show any changes. In the second section of this study, we analyzed the effects of the drug on coronary blood flow and resistance in 8 patients without clinical and/or objective evidence of coronary artery disease. Using thermodilution technique, the coronary sinus blood flow (CSBF) and coronary resistance (CR) were measured in basal condition and 5, 10, 15 and 30 min after 0.05 mg/Kg iv gallopamil. We observed a significant (p less than 0.001) increase of CSBF after 10 min and a significant decrease of CR after 10 min (p less than 0.001) and 15 min (p less than 0.05). In conclusion, our results suggest that the anti-ischemic effect of gallopamil can be related not only to the reduction of myocardial oxygen requirement, but also to an improvement of coronary blood flow with a decrease in coronary resistance.

Adult↗
PubMed1990

Evaluation of the effects of gallopamil in patients with effort angina by transesophageal atrial pacing two-dimensional echocardiography.

Transesophageal atrial pacing (TAP) 2D echocardiography was performed after placebo (P) and gallopamil (G) (0.03 mg/kg iv) in 12 patients with stable, reproducible, effort angina. If compared to P study, during G the following changes were observed: 3 out of the 12 patients did not experience angina, time to ST-1mm increased from 5.3 +/- 1.3 to 6.6 +/- 1.6 min (p less than 0.05), wall motion score was improved both at 130 b/min (15.3 +/- 4.1 drug P, 17 +/- 4.8 drug G, p less than 0.01) and at 150 b/min (10.9 +/- 5.7 drug P, 12.8 +/- 6.3 drug G, p = 0.07). In conclusion, gallopamil has a beneficial effect on atrial pacing induced ischemia: it increases pacing time to ischemic threshold and reduces during ischemia the extent of dysfunctional myocardium.

Aged↗
PubMed1990

[Evaluation of coronary anatomy and coronary circulation by transesophageal echocardiography].

UNLABELLED: Nowadays the anatomy and coronary flow can be evaluated by means of various methods requiring cardiac catheterization. Transesophageal echocardiography is a new diagnostic method with great potential (excellent technical quality, stable positioning of the transducer, no lung interposition). Because of its potential we have used transesophageal echocardiography on a number of patients undergoing coronary angiography in order to investigate its reliability in estimating the anatomy and coronary flow. From the anatomical point of view 3 aspects were identified: absence of alterations affecting the vessel being explored (Criterion A); presence of non-stenotic calcific wall plaques (Criterion B); presence of stenotic calcific plaques (Criterion C). The percentage of visualization of the left main artery, the left anterior descending and the circumflex was 87%, 78% and 76% respectively. The criteria described showed varying reliability depending on the coronary portion being considered. Using the pulsed Doppler, during the transesophageal study, we obtained an adequate recording of the velocity profile of the left anterior descending in 28/37 patients. After dipyridamole infusion all velocity parameters (diastolic and systolic mean and maximum velocities) increased significantly in those patients with left anterior descending without stenosis, while remaining practically constant in those patients with significant stenosis of the left anterior descending artery. In particular the ratio between the maximum diastolic velocity recorded after dipyridamole and the velocity recorded immediately before infusion was significantly greater in those subjects with normal left anterior descending than in those with significant stenosis of the left anterior descending artery. CONCLUSIONS: transesophageal echocardiography offers new prospects in studying anatomic alterations and flow patterns of the proximal part of the left coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Electrophysiologic evaluation of intravenous nicardipine in man.

The acute electrophysiological effects of intravenous nicardipine (0.014 mg/kg per min for 5 minutes) were studied in 12 subjects with estimated normal sinus node functions and atrioventricular conduction parameters. The most important effects were sinus cycle length shortening, increase of corrected sinus node recovery time and reduction of effective and functional refractory period of the atrioventricular node. Sinuatrial conduction time, atrial refractory periods, intranodal conduction, bundle branch refractoriness and ventricular refractoriness were unchanged. Systolic and diastolic blood pressure was reduced. The clinical implications of these properties of the drug are discussed and compared with those of verapamil, diltiazem and nifedipine.

Blood Pressure↗
PubMed1989

Usefulness of transesophageal atrial pacing in hyperkalemia-induced impulse formation and conduction disturbances.

This report describes the usefulness of transesophageal atrial pacing in the treatment of five patients with hyperkalemia-induced bradycardias. Three patients had marked sinus bradycardia while the other two had a regular rhythm with QRS of left bundle branch block morphology, with no P waves visible on the surface electrocardiogram. Four patients were in chronic hemodialysis three times a week, and one had severe post-traumatic hemorrhage. In three patients, hyperkalemia had been precipitated by food intoxication. In one case the cause was unknown while, in the last case, hyperkalemia was due to rapid infusion of stored blood and solutions containing high concentrations of potassium. Transesophageal atrial pacing was performed in all cases utilizing a bipolar catheter introduced into the esophagus and a constant current generator delivering square wave pulses of 10 msec duration and 19-28 mA intensity. Atrial capture, followed by impulse conduction to the ventricles, was constant in all cases, being performed for between 15 and 35 minutes until a normal sinus rhythm was restored. The procedure was well tolerated. The advantages of this procedure as opposed to invasive ventricular pacing are discussed.

Aged↗
PubMed1989

Functional and structural abnormalities in patients with dilated cardiomyopathy.

Passive diastolic properties of the left ventricle were determined in 10 control subjects and 12 patients with dilated cardiomyopathy. Simultaneous left ventricular angiography and high fidelity pressure measurements were performed in all patients. Left ventricular chamber stiffness was calculated from left ventricular pressure-volume and myocardial stiffness from left ventricular stress-strain relations with use of a viscoelastic model. Patients with dilated cardiomyopathy were classified into two groups according to the diastolic constant of myocardial stiffness (beta). Group 1 consisted of seven patients with a normal constant of myocardial stiffness less than or equal to 9.6 (normal range 2.2 to 9.6) and group 2 of 5 patients with a beta greater than 9.6. Structural abnormalities (percent interstitial fibrosis, fibrous content) in patients with dilated cardiomyopathy were assessed by morphometry from right ventricular endomyocardial biopsies. Heart rate was similar in the three groups. Left ventricular end-diastolic pressure was significantly greater in patients with cardiomyopathy (18 mm Hg in group 1 and 22 mm Hg in group 2) than in the control patients (10 mm Hg). Left ventricular ejection fraction was significantly lower in groups 1 (37%) and 2 (36%) than in the control patients (66%). Left ventricular muscle mass index was significantly increased in both groups with cardiomyopathy. The constant of chamber stiffness (beta*) was slightly although not significantly greater in groups 1 and 2 (0.58 and 0.58, respectively) than in the control group (0.35). The constant of myocardial stiffness beta was normal in group 1 (7.0; control group 6.9, p = NS) but was significantly increased in group 2 (23.5). Interstitial fibrosis was 19% in group 1 and 43% (p less than 0.001) in group 2 (normal less than or equal to 10%). There was an exponential relation between both diastolic constant of myocardial stiffness (beta) and interstitial fibrosis (IF) (r = 0.95; p less than 0.001) and beta and fibrous content divided by end-diastolic volume index (r = 0.93; p less than 0.001). It is concluded that myocardial stiffness can be normal in patients with dilated cardiomyopathy despite severely depressed systolic function. Structural alterations of the myocardium with increased amounts of fibrous tissues are probably responsible for the observed changes in passive elastic properties of the myocardium in patients with dilated cardiomyopathy. The constant of myocardial stiffness (beta) helps to identify patients with severe structural alterations (group 2), representing possibly a more advanced stage of the disease.

Adult↗
PubMed1989

Polymorphism of the clinical picture.

There is increasing evidence that a cardiomyopathy with preferential, mild to moderate (at least in the early phase) RV involvement, characterized by some peculiar segmental wall motion abnormalities and by adipose or fibro-adipose tissue infiltration, is the underlying anomaly in a wide spectrum of clinical conditions. At one end of this spectrum stand malignant ventricular tachyarrhythmias which are infrequent and generally symptomatic. Common features in the majority of cases are frequent and sometimes complex PVBs, mostly, though not exclusively, originating in the RV, which may be asymptomatic, exercise-related only in some cases, and are often associated with T-wave abnormalities. Then, at the other end of this spectrum we may find patients without arrhythmias complaining of precordial pain. Physical examination in the minor form subgroups is generally negative as, in most cases, are non-invasive investigations. Diagnosis in these minor form subgroups is thus mainly based on right ventriculography and RV biopsy, although the diagnostic criteria are not yet completely defined. So, we are now often faced with the dilemma of whether or not to submit these patients to invasive investigations which, at the moment, seem the most appropriate diagnostic approach.

Adult↗
PubMed1989

Echo Doppler evaluation of right ventricular dysplasia.

Two-dimensional echocardiography (2D echo) and Doppler were performed in a group of patients who had a high probability of having right ventricular (RV) dysplasia (left bundle branch block arrhythmias, no signs of cardiopulmonary diseases) and in a group of age-matched normals. 2D echo showed RV morphofunctional abnormalities (free wall and apical irregularities, wall motion abnormalities) in 25% of patients with suspected RV dysplasia but in none of the normals. Concordance with angiography was good (75% of cases with positive 2D echo study had a positive angiography, while only 33% of the patients with suspected RV dysplasia and negative 2D echo had a positive angiography). In patients with high probability of RV dysplasia (positive 2D echo and angiography) left ventricular filling was similar to that of normal subjects whereas RV filling was markedly rearranged, as demonstrated by the significant decrease in RV early-to-atrial peak flow velocities.

Adolescent↗
PubMed1989

Right ventricular dysplasia: angiographic study.

At the moment, the most reliable method for diagnosing right ventricular dysplasia is considered to be angiography. Morphological alterations such as the presence of akinetic/dyskinetic areas, aneurysmatic dilatations and deep anteroapical fissuring, not necessarily associated with an increase in ventricular volume, are understood to be angiographic criteria indicating dysplasia. To verify their diagnostic value, these abnormalities have been evaluated in: (1) 33 patients suspected of having dysplasia because of PVBs with LBBB morphology and with 'borderline' involvement of the right ventricle or without instrumental evidence of cardiac disease (Group A); (2) 16 subjects with no arrhythmia and normal left ventricular angiography, coronary and bioptic findings (Group B); (3) 36 patients with a clinical, angiographic and bioptic diagnosis of dilated idiopathic cardiomyopathy (Group C). In 48.5% of the patients in Group A, angiography showed localized akinesia/dyskinesia (12 patients), small conical outpouchings persisting during systole (10 patients) and apical deep fissuring (two patients). In 81% of these patients, endomyocardial biopsy showed the presence of fibrous and/or adipose tissue in at least 20% of the examined sample. Angiographic abnormalities suggesting dysplasia were found in none of the normal subjects and only in two of the 36 patients with dilated cardiomyopathy (5.5%).

Adolescent↗
PubMed1989

Programmed stimulation in patients with minor forms of right ventricular dysplasia.

Programmed electrical stimulation (PES) was performed in 17 patients, mean age 31 +/- 8 years, with minor forms of right ventricular dysplasia diagnosed because of (1) premature ventricular beats (PVBs) of left bundle branch block (LBBB) morphology; (2) no clinical or non-invasive evidence of cardiac abnormalities; (3) angiographic evidence of right ventricular wall motion abnormalities and bioptic findings of fibro-adipose infiltration. Fifteen patients had frequent and complex PVBs while two had sustained ventricular tachycardia (VT). During PES, sustained VT was induced in 2/2 patients with spontaneous sustained VT; ventricular repetitive responses were induced in 2/15 cases (13%) with complex and frequent PVBs. In conclusion, in minor forms of right ventricular dysplasia, PES induces VT only in patients with clinical VT; on the contrary, in patients with PVBs it is only possible to induce repetitive ventricular responses in a small proportion of cases; it is therefore not possible to select patients at high risk of developing severe ventricular arrhythmias.

Adult↗
PubMed1989

Objective evaluation of gallopamil in patients with chronic stable angina. Exercise testing, Holter monitoring, cross-sectional echocardiography and plasma levels.

In this double-blind, randomized placebo-controlled study the effects of two dosages of gallopamil on exercise tolerance were evaluated in 12 patients with stable effort angina. After a pre-study screening aimed at assessing the reproducibility of the exercise response, the patients entered the study which consisted of three 7-day consecutive periods during which placebo or gallopamil 50 mg t.i.d. or gallopamil 75 mg t.i.d. were administered according to a randomized sequence. 24-hour Holter monitoring and cross-sectional echocardiography were performed on the 6th and 7th day of each treatment period, respectively. On the 7th day of each treatment period, patients underwent an exercise test 2 and 8 h after the last administration of gallopamil or placebo. Blood samples for plasma gallopamil concentrations were taken just before each exercise test. The results were analysed using a three-way analysis of variance; intergroup differences were evaluated by the Newman-Keuls test. At 2 h, 11 patients with placebo and three with gallopamil experienced angina; both dosages of gallopamil significantly prolonged exercise time and -1 mm time and also reduced ST segment depression and the rate-pressure product at submaximal workload. No significant change in the rate-pressure product was observed either on the appearance of 1 mm ST depression or at peak exercise. At 8 h, 11 patients with placebo and gallopamil 50 mg t.i.d. and 10 with gallopamil 75 mg t.i.d. experienced angina; although exercise time was significantly prolonged by both dosages of gallopamil, the increase in -1 mm time and reduction of ST segment depression at submaximal workload did not reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗