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Biomedical subjects

P Rizzon

Publications and source records attributed to P Rizzon.

At least 91 records · Page 5Linked to original sources
PubMed1994

Coronary flow dynamics and reserve assessed by transesophageal echocardiography in obstructive hypertrophic cardiomyopathy.

Myocardial ischemia is frequently associated with left ventricular outflow obstruction. To assess coronary flow impairment in obstructive hypertrophic cardiomyopathy (HC), 10 patients with echo-Doppler-detected obstructive HC and normal coronary arteries underwent transesophageal echo-Doppler examination of both coronary flow velocity (CFV) at rest, recorded in the proximal left anterior descending coronary artery, and coronary flow reserve (CFR) evaluated by means of dipyridamole infusion response. Ten normal patients were similarly studied and served as a control group. Two relevant alterations in coronary flow dynamics were detected in patients with HC: (1) a significantly increased diastolic/systolic CFV ratio, and (2) a significantly reduced dipyridamole/baseline CFV ratio. Compared with normal subjects, the CFV pattern showed a significantly greater diastolic and a significantly lower systolic component at rest (in some patients it was reversed). Diastolic/systolic CFV ratio was significantly higher in patients with HC at baseline (3.1 +/- 1 vs 1.6 +/- 0.5; p < 0.01) and increased further after dipyridamole infusion (4.9 +/- 2 vs 2.2 +/- 0.7; p < 0.01). In addition, CFR was impaired in patients with HC (1.8 +/- 0.3 vs 3.1 +/- 0.5; p < 0.01). Furthermore, a significant correlation between CFR and intraventricular pressure gradient was found. Thus, transesophageal echo-Doppler examination is a useful tool for evaluating CFV dynamics and CFR as demonstrated in patients with obstructive HC.

Aged↗
PubMed1994

Improved Doppler signal intensity in coronary arteries after intravenous peripheral injection of a lung-crossing contrast agent (SHU 508A)

OBJECTIVES: We tested the hypothesis that SHU 508A, a new lung-crossing contrast agent capable of increasing the Doppler signal to noise ratio in the right heart as well as left heart cavities after intravenous injection, could increase Doppler signal intensity in coronary arteries, thus improving the feasibility and quality of transesophageal Doppler echocardiographic evaluation of coronary blood flow velocity. BACKGROUND: Coronary blood flow velocity can be evaluated by transesophageal Doppler echocardiography. However, an adequate Doppler tracing is obtainable in a relatively low percent of patients. METHODS: Transesophageal Doppler echocardiography of coronary arteries was performed in 35 patients before and after SHU 508A injection at four different dosages (200 mg/ml in 5 ml, 200 mg/ml in 10 ml, 300 mg/ml in 5 ml and 300 mg/ml in 10 ml). Color Doppler mapping of coronary flow and pulsed wave Doppler measurement of coronary blood flow velocity were attempted in all patients. RESULTS: Color Doppler flow mapping of 105 evaluated coronary segments (left main, left anterior descending and circumflex in 35 patients) was not detectable or was weak in 88% of patients before and 33% of patients after echo contrast injection (p < 0.0001); it was optimal (that is, well delineated with complete flow mapping of the explored vessel) in only 11% of patients before and 67% after echo contrast injection (p < 0.0001). In addition, pulsed wave Doppler signal quality improved after echo contrast injection: Pulsed wave Doppler recording of coronary blood flow velocity was not obtainable or was weak in 78% of cases before and 34% after echo contrast injection (p < 0.0001); pulsed wave Doppler recording of coronary blood flow velocity was optimal (that is, there was a complete and well defined outline of diastolic coronary blood flow velocity in 23% of cases before and 66% after echo contrast injection [p < 0.0001]. Both length and width of color Doppler mapping in the left anterior descending coronary artery increased after SHU 508A injection (from 5.75 +/- 5.32 and 1.51 +/- 1.17 to 17.04 +/- 8.76 and 4.21 +/- 1.78 mm, respectively, mean +/- SD, p < 0.0001). CONCLUSIONS: The feasibility and quality of recording coronary blood flow velocity by transesophageal Doppler echocardiography are considerably improved by intravenous injection of SHU 508A. The improved feasibility of this new semi-invasive method for evaluating coronary blood flow velocity and flow reserve can considerably increase its research and clinical utilization.

Aged↗
PubMed1994

Detection of coronary artery disease by digital stress echocardiography: comparison of exercise, transesophageal atrial pacing and dipyridamole echocardiography.

OBJECTIVES: This study assessed and compared the diagnostic potential of exercise, transesophageal atrial pacing and dipyridamole stress echocardiography in a clinical setting. BACKGROUND: Although they have been widely studied, no data exist with regard to comparisons of these procedures in a head-to-head study in different clinical settings. METHODS: One hundred four consecutive patients with suspected coronary artery disease undergoing coronary angiography and with no previous myocardial infarction or rest left ventricular wall motion abnormalities underwent digital posttreadmill, transesophageal atrial pacing and dipyridamole echocardiography. RESULTS: Feasibility of digital exercise echocardiography was 84%; 8 of 88 remaining patients had a nondiagnostic exercise echocardiographic test (inadequate exercise or imaging). In 80 patients with feasible and diagnostic digital exercise echocardiography, sensitivity, specificity and accuracy were, respectively, 89%, 91% and 90%. Eighty of the 104 patients underwent transesophageal atrial pacing and dipyridamole echocardiography. Feasibility of the alternative stress procedures was 77% for transesophageal atrial pacing and 96% for dipyridamole. In 60 patients successfully undergoing both alternative stress procedures, sensitivity and specificity were 83% and 76% for atrial pacing and 43% and 92% for dipyridamole echocardiography, respectively. In the group of 24 patients with nondiagnostic exercise echocardiography and consequent indication to alternative stress procedures, accuracy of transesophageal atrial pacing was higher than that of dipyridamole echocardiography (73% vs. 45%, p = 0.06). CONCLUSIONS: Because of its higher diagnostic potential and additional functional information, exercise is the stress of choice when stress echocardiography is used to detect the presence of coronary artery disease. Alternative stresses can be used in patients with nondiagnostic exercise echocardiography. Transesophageal and dipyridamole echocardiography differ in feasibility and diagnostic reliability (higher sensitivity of transesophageal atrial pacing, higher specificity of dipyridamole). These characteristics must be considered when selecting procedures to be used as alternatives to exercise.

Aged↗
PubMed1994

Clinical use of stress echocardiography: factors affecting diagnostic accuracy.

Stress echocardiography is frequently used for the diagnosis of coronary artery disease. Its diagnostic accuracy is strongly influenced by many variables including patient selection, type of stress procedure utilized, stress protocol, echocardiographic imaging modality, digital reviewing technology and expertise in performing and interpreting the examinations. All these must be taken into consideration when evaluating and comparing different studies presented in the literature, as well as in optimal organization (accurate selection of the appropriate stress modality and protocol execution, optimal use of technology, appropriate training of medical and non-medical personnel) of the laboratory involved in stress echocardiography.

Adult↗
PubMed1994

Prediction of mortality in mild to moderately symptomatic patients with left ventricular dysfunction. The role of the New York Heart Association classification, cardiopulmonary exercise testing, two-dimensional echocardiography and Holter monitoring.

In order to investigate the value of peak oxygen consumption (peak VO2) in predicting mortality in mild to moderately symptomatic patients with left ventricular dysfunction, we studied 103 NYHA II/III class patients with a left ventricular ejection fraction (LVEF) < or = 40%. Heart failure was due to coronary artery disease (CAD) in 39 patients, idiopathic dilated cardiomyopathy in 54, hypertension in eight and surgically corrected valvular disease in two. The following variables were analysed: age, cause of heart failure (CAD vs no CAD), NYHA class, peak VO2, LVEF, left ventricular end-systolic volume index (LVESVI), ventricular tachycardia (VT) on Holter monitoring and the use of antiarrhythmic drugs. Statistical analysis was performed by Cox's proportional-hazards regression model. During a mean follow-up period of 20 months, there were 25 deaths. The estimated cumulative probabilities of survival were 88%, 73% and 58% at 1, 2 and 3 years, respectively. Cox's model identified CAD (P = 0.01), NYHA III class (P = 0.04) and LVEF (P = 0.02) as independent, statistically significant predictors of mortality. Peak VO2 had only a marginal statistical significance (P = 0.07). Age, LVESVI, VT on Holter monitoring and use of antiarrhythmic drugs were not related to mortality. These data can be important in patient clinical management and clinical trial design.

Adult↗
PubMed1994

Effects of lacidipine and nifedipine on lower limb veins in nonphlebopathic patients.

The aim of this study was to evaluate the effect of lacidipine and nifedipine on lower limb veins. Forty hypertensive patients, aged 30-50 years, with no deep venous thrombosis, venous insufficiency, or hypothyroidism underwent double-blind treatment with placebo (1 week), lacidipine 4 mg once daily (1 week), and slow-release nifedipine 20 mg twice daily (1 week) in randomized sequence. Echo-color Doppler examination of superficial, deep, communicating, and perforating veins of the legs was performed. The results showed venous insufficiency and hypertension after 1-week administration of lacidipine (5 and 15%, respectively) and nifedipine (10 and 25%, respectively) and only two cases (5%) of venous hypertension during placebo administration. Lower limb edema was observed in two patients (5%) during treatment with nifedipine slow-release (SR). The hemodynamic effects of lacidipine and nifedipine were reversible but may contribute to the mechanism of lower limb edema.

Adult↗
PubMed1994

[Assessment of viable myocardium after infarction with transesophageal echocardiography and myocardial echocontrastography].

Left ventricular recovery of dysfunctioning but viable myocardium can occur only in tissue in which both myocardial contractile reserve and microvascular integrity are preserved. Recent studies have demonstrated that both inotropic stimulating echo tests and myocardial contrast echocardiography can be used to assess myocardial viability in post-myocardial infarction patients. Therefore we performed a transesophageal and myocardial contrast echocardiographic evaluation of post-myocardial infarction patients to assess: the respective accuracy of post-extrasystolic potentiation and low-dose dobutamine (5 and 10 mcg) during transesophageal echocardiography in eliciting contractile reserve, and the potential of myocardial contrast echocardiography in predicting later functional recovery. Results of our studies showed comparable effects of low-dose dobutamine (5 mcg) and post-extrasystolic potentiation in increasing myocardial thickening while low-dose dobutamine (10 mcg) had a greater potential in eliciting residual contractility. Lastly, myocardial contrast echocardiography provided a clear spectrum of intramyocardial perfusion patterns in dysfunctioning areas but did not accurately correlate with later functional recovery as better predicted by low-dose dobutamine in the same segments. In conclusion, these methods represent the preferred choice of studying the perfusion-contraction match in viable myocardium thus playing an important role in prognostic and therapeutic strategies in myocardial infarction patients.

Echocardiography↗
PubMed1994

[Myocardial viability in acute myocardial infarction and verapamil].

Following prolonged ischemia, if not adequately reperfused, myocardium undergoes necrosis, scarring and thinning. The myocardium tends to dilate in the noninfarcted ventricular area, giving rise to ventricular remodelling. If the ischemic myocardium is adequately reperfused it can be saved and its temporarily depressed functions eventually be recuperated (viable myocardium). The extent of recovery of the postinfarction viable myocardium seems to affect ventricular remodelling. The integrity of the microcirculation of the non-contractile myocardium following prolonged ischemia is fundamental in maintaining a contractile reserve adequate enough for a functional recovery (myocardial viability). Protection of the microcirculation during ischemia-reperfusion is therefore of great importance for the role that the microcirculation plays in ensuring myocardial viability. Experimental studies and initial clinical observations showed that calcium-antagonists exert a beneficial effect in this respect. VAMI is a multicentre, randomized double-blind, placebo-controlled study whose aim is to ascertain the potentiality of verapamil in limiting regional functional damage in patients with acute myocardial infarction and undergoing early thrombolysis.

Double-Blind Method↗
PubMed1994

[Assessment of the autonomic nervous system in the acute phase of myocardial infarction].

The aim of this study was to evaluate how heart rate variability changes during acute myocardial infarction (AMI) and whether this change is different in anterior and inferior AMI. For this purpose 10 patients with anterior (mean age 53 +/- 11 years) and 11 patients with inferior (mean age 55 +/- 11 years) AMI underwent 2 consecutive 24-hour Holter recordings (H1, H2) which started, at most, 6 hours after the onset of symptoms and a further two H at the 10th (H3), and 28th day (H4) of AMI. None of the patients suffered from diabetes or was taking beta-blockers. The standard deviation of the RR intervals (SDRR) for a 24-hour period was evaluated for each H in the group of patients with anterior and inferior AMI. In H1, SDRR was statistically lower in anterior compared to inferior AMI (64 +/- 20 versus 106 +/- 27; p < 0.0001). No statistically significant differences were found in H2 between the anterior and inferior AMI (72 +/- 19 versus 76 +/- 14), due to a reduction in SDRR in inferior AMI: from 106 +/- 27 in H1 to 76 +/- 14 in H2; p < 0.002. No statistically significant changes were present in anterior AMI patients between H1 and H2 (64 +/- 20 versus 72 +/- 19). SDRR recovers at H3 increasing in both groups (anterior: 101 +/- 28, p < 0.001; inferior: 108 +/- 29, p < 0.004). No further significant changes in SDRR were present at H4 for either group (anterior 117 +/- 30; inferior: 118 +/- 31).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Prevention of post-infarction remodelling with L-carnitine: multicenter study CEDIM (L-Carnitine digital echocardiography myocardial infarction)].

Prevention of post-infarction ventricular remodeling is an important therapeutic aim since left ventricular dilatation is one of the most important prognostic post-infarction determinants. Early reperfusion and chronic treatment with ACE-inhibitors are able to limit remodeling by means of two distinct mechanisms. Early reperfusion limits the extent of the infarcted area by salvaging a part of the myocardial area at risk of necrosis. ACE-inhibition, on the other hand, by reducing afterload, facilitates cardiac ejection and therefore tends to reduce left ventricular volume. Remodeling could be limited also by drugs which, like L-carnitine, act, as has been demonstrated by experimental studies, on the use of energy substrates both in the area at risk of necrosis and in the area subjected to a greater wall stress because of remodeling and which will progressively dilate over time. The CEDIM study is a double-blind, randomized, placebo-controlled, multicentre trial which has involved 36 Heart Divisions. The CEDIM study aims at evaluating the effects of L-carnitine on left ventricular function, as assessed by echocardiography, in patients with acute anterior myocardial infarction.

Carnitine↗
PubMed1994

[The echocardiographic assessment of the functional variations in the left ventricle induced by isometric stress in subjects with primary cardiomyopathy in the pre-dilated phase].

The aim of this study was to assess whether a sudden increase in left ventricular (LV) afterload in a pre-dilated condition of idiopathic cardiomyopathy, in associated with some non-invasively detectable impairment of LV function. Ten subjects (Group A, 7 males, 3 females, mean age 36.7 +/- 11.4 years), submitted to cardiac catheterization because of severe symptoms related to ventricular arrhythmias, were found to have normal coronary arteries and left ventricular function, but histological features suggestive of congestive cardiomyopathy at endomyocardial biopsy. Echocardiography was performed during handgrip for 5 min at 30% of the maximal effort, in order to obtain a sharp increase in systolic LV pressure of more than 40 mm Hg. Ten healthy subjects were used as controls (Group B). Results in Group A showed a significant decrease in LV ejection fraction (from 62.4 +/- 6.9 to 57 +/- 7; p < 0.005) and LV shortening fraction (from 34.2 +/- 5.1 to 31 +/- 4.3; p < 0.01); a significant increase in LV systolic volume (from 48.2 +/- 9.1 to 60.0 +/- 12.0; p < 0.005) and systolic stress (from 114.6 +/- 33.2 to 178.8 +/- 58.2; p < 0.001). At the first minute of recovery LV function normalized quickly while LV systolic volume remained moderately increased (52.5 +/- 10.2). In conclusion, in pre-congestive dilated cardiomyopathy a latent impairment in LV function can be detected during a sharp increase of LV afterload. Isometric stress is particularly useful in eliciting these transient changes, as the method allows a reliable echocardiographic examination during maximal stress and not only during the recovery phase, as in dynamic stress.

Adult↗
PubMed1994

[Diltiazem helps perfusion of the kidney after transplantation: intraoperative assessment using echo-color Doppler].

Diltiazem is a dihydropyridinic calcium-antagonist which acts an arterial muscle, producing an increase in vascular capacity. We administered it intraoperatively in 2 patients subjected to kidney transplantation, to asses the maximal vascular reserve of the transplanted organ. After 2' and 10' from administration of Diltiazem, Color Doppler Ultrasound showed a 30% increase in mean flow in the renal artery and 13% reduction in the intraparenchymal resistance rates with respect to the basal parameters. Systemic arterious pressure remained unchanged. This result was associated with an improvement in the perfusion of the transplanted organ.

Diltiazem↗
PubMed1993

Tachycardia and coronary blood flow: non-invasive estimation during Valsalva manoeuvre and exercise.

Simultaneous changes in cycle length and coronary blood flow were studied during Valsalva manoeuvre and supine cycloergometer exercise test in 10 male patients (mean age 48 +/- 12 years) who had successfully undergone myocardial revascularization by surgical anastomosis of the left internal mammary artery on the left anterior descending coronary artery. Blood velocity curves in the left internal mammary artery were obtained by a non-invasive continuous-wave Doppler probe at rest, in the last phase of the expiratory effort of the Valsalva manoeuvre and at the maximum load attained during the exercise test. Mean arterial pressure by sphygmomanometer, and cardiac cycle length on the basis of Doppler recording were measured. Mean blood velocity, the length of the blood column entering the coronary bed at each cycle (cardiac cycle times mean velocity), an index of blood cell acceleration (the ratio of mean velocity to cardiac cycle), and an index of coronary resistance (the ratio of mean pressure to mean velocity), were calculated. For approximately the same change in cycle length, coronary resistance decreased in exercise, with an increased mean velocity, but increased in Valsalva, with no changes in mean velocity. The length of the blood column entering the coronary bed at each cycle was unchanged in exercise, with a marked increase in the acceleration index, while it decreased in Valsalva. Therefore, we hypothesize that tachycardia has a limiting effect on sympathetic coronary constriction in Valsalva when cardiac external work is decreased, and an additional vasodilatory effect on coronary bed in exercise when external work is increased.

Adult↗
PubMed1993

Determination of arterial diameters, length and mass of the plaque, and theoretical volume in the internal carotid artery by quantitative vascular echography.

To study the evolution of atherosclerosis, the consensual changes that occur in the arterial wall, lumen, and atheroma must be evaluated. The authors propose a new, noninvasive method of obtaining arterial diameters, length and mass of plaque, and theoretical volume in the internal carotid artery. The study was performed in 37 patients with different degrees of atherosclerosis (from 20% to 50%). All patients underwent echo examination. Long-axis tomographic planes were recorded with the same angle of incidence by placing a goniometer around the neck. Furthermore, the arterial diameters and the plaque length were measured from photorecordings, and theoretical arterial volume (sum of two bitruncated semiellipsoids), residual volume (Simpson's integral rule), and plaque mass (difference between theoretical vascular volume and residual volume) were calculated. Intraobserver and interobserver variability and reproducibility were tested in all the measurements and calculations. Intraobserver/interobserver variability and reproducibility were found to be less than 8% according to all measurements and calculations. These results indicate that the method is reproducible and allows noninvasive, quantitative assessments of vascular geometry in evolving atherosclerosis.

Arteriosclerosis↗