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Biomedical subjects

F Rengo

Publications and source records attributed to F Rengo.

At least 145 records · Page 8Linked to original sources
PubMed1986

[Beneficial effects of diltiazem in exertion stable angina. Evaluation of coronary hemodynamics during cardiac pacing].

We evaluated the protective effect of Diltiazem from pacing-induced myocardial ischemia in 9 patients (pts) with coronary heart disease (CAD) and stable effort angina by studying the changes in systemic and coronary hemodynamics during pacing. Hemodynamic parameters were evaluated at baseline and at peak pacing before and after Diltiazem, 25 mg i.v. Diltiazem prevented angina in 6 of 7 pts who presented angina in the control pacing. This beneficial effect was accompanied at peak pacing rate by a significant fall in ST depression, arterial pressure, rate-pressure product and left ventricular (LV) end-diastolic pressure, while no significant changes were observed in LV dp/dt max, coronary blood flow and coronary vascular resistance. Therefore, Diltiazem exerts a protective effect from pacing-induced myocardial ischemia in pts with CAD and stable effort angina, without impairing LV function. This beneficial effect is due to a reduction in myocardial metabolic requirements, rather than to an improvement of blood supply to the ischemic myocardium.

Aged↗
PubMed1986

Effect of mexiletine on reperfusion-induced ventricular arrhythmias: comparison with lidocaine.

Thirty mongrel dogs underwent proximal occlusion of the left anterior descending coronary artery to evaluate the comparative action of mexiletine and lidocaine on ventricular arrhythmias during myocardial reperfusion. Heart rate, arterial blood pressure, left ventricular end-diastolic pressure and dp/dt max were evaluated before and at the 20th and 25th min after coronary occlusion; at the 25th min coronary occlusion was removed. Dogs were randomly assigned to one of the following groups of 10: 1) control group; 2) dogs given i.v. mexiletine; 3) dogs given i.v. lidocaine. As expected, during ischemia, myocardial contractility decreased after mexiletine or lidocaine administration more than in the control group. Ventricular arrhythmias during myocardial reperfusion occurred in 9 dogs of the control group (ventricular tachycardia in 2 cases and ventricular fibrillation in 7 cases). Among dogs given mexiletine only 1 had ventricular fibrillation (p less than 0.001 vs control). Six of the 10 dogs given lidocaine had ventricular arrhythmias (ventricular tachycardia in 5 cases and ventricular fibrillation in 1 case) (p = ns vs control group; p less than 0.05 vs mexiletine group). Thus mexiletine and lidocaine had similar effects on cardiac function during myocardial ischemia and only mexiletine showed a protective effect against reperfusion ventricular arrhythmias.

Animals↗
PubMed1985

[Effect of beta-receptor block on QT/QS2 behavior during isometric and dynamic exercise].

Our study is aimed to evaluate the change of QT/QS2 ratio in normal subjects during both isometric and dynamic exercise before and after propranolol administration. We studied 10 young volunteers healthy subjects who performed an isometric exercise by squeezing a grip dynamometer at 70% of their maximal voluntary contraction as long as possible. They also performed a dynamic exercise undergoing a submaximal bicycle stress test. Both tests were performed before and after administration of propranolol (0.15 mg/Kg e.v.) QT and QS2 intervals were measured at rest, during exercise and in the recovery period. Heart rate and blood pressure were also determined. Isometric exercise induces a significant shortening of both intervals although minor for QT so that the ratio significantly increases in comparison to baseline (p less than .001). At rest propranolol induces a significant decrease of heart rate and only a slight lengthening of QT and QS2 so that the ratio is unchanged. During exercise propranolol does not influence the increase of heart rate and blood pressure and the shortening of QT interval but prevent exercise-induced QS2 shortening so that the ratio after beta-blockade is significantly reduced at the peak of exercise (p less than .005). During dynamic exercise QT and QS2 behaviour is similar to that of isometric exercise; in fact both intervals are shortened and QS2 decrease is major than QT so that the ratio increases (p less than .001). These results confirm that QT/QS2 ratio can monitor the effects of adrenergic stimulation on the heart during physiological manoeuvres enhancing sympathetic discharge like occurs during both isometric and dynamic exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Influence of heart rate on exercise-induced R-wave amplitude changes in coronary patients and normal subjects.

In order to study whether different heart rates achieved at peak exercise by normal subjects and patients with coronary artery disease (CAD) affect the results of analysis of R-wave amplitude changes (delta R), we evaluated delta R at progressively increasing heart rate (HR) steps in 60 normal subjects with negative exercise tests (ET), in 130 patients with CAD, in 88 patients with true positive and 42 with false negative ET, and in 43 patients with no CAD and false positive ET. We found that the sensitivity and specificity of delta R were HR dependent, the former decreasing and the latter increasing with progressively increasing HR steps. Mean values of delta R did not discriminate among the four groups for HRs up to 150 bpm; significant differences were found between normal subjects and CAD patients, both with true positive and false negative stress tests, at HR greater than 150 bpm. False positive patients had mean delta R similar to those found in normal subjects. We hypothesize that quantitative delta R analysis could be useful in ECG diagnosis of false negative and false positive patients at HR greater than 150 bpm.

Coronary Disease↗
PubMed1984

Quantitative and qualitative analysis of the relationship between exercise-induced R wave amplitude changes and severity of coronary artery disease.

The correlation between R wave voltage variations (delta R) and the angiographic severity of coronary artery disease (CAD) at progressively increasing heart rate (HR) steps was evaluated in 51 patients (pts) without CAD (OV), in 42 pts with single (SVD), in 43 with double (DVD) and in 59 pts with triple vessel disease (TVD). At the end of stress the sensitivity of delta R was higher in DVD and TVD pts than in SVD pts. There was no clear correlation between exercise-induced R wave changes and the angiographic severity of CAD, since the qualitative and quantitative delta R evaluation during effort showed similar changes in delta R for a wide range of HR's in the entire study population. Since different degrees of exercise tolerance were found in pts with SVD, DVD and TVD, we hypothesize that the correlation between delta R and the severity of CAD at the end of stress testing may be artifactual.

Analysis of Variance↗
PubMed1984

[Relation between the QT interval and the severity of ventricular arrhythmias in the early phases of myocardial infarct].

The purpose of our research was to evaluate the relationship between the severity of ventricular arrhythmias in the first hours of myocardial infarction and the duration of electrical systole (QT). Twelve-lead resting electrocardiograms (ECGs) of 66 non-consecutive patients admitted to our Coronary Care Unit for myocardial infarction were retrospectively evaluated. Criteria for retrospective selection of patients were the following: 1) admission to the coronary care unit within 12 hours from the onset of myocardial infarction symptoms; 2) appropriate ECG changes suggesting acute transmural infarction (pathologic Q waves, envolving ST changes) and diagnostic elevation of serum enzymes activity; 3) good-quality ECG recordings with sinus rhythm and no conduction defects, recorded before the beginning of therapy and within the first hours after the onset of symptoms. After this first selection, the following criteria of exclusion were applied: 1) abnormal values of serum Ca++ and K+; 2) historical and/or electrocardiographic findings of a previous myocardial infarction; 3) chronic treatment with antiarrhythmic or beta-blocking drugs, digitalis or other drugs affecting the QT interval; 4) administration of drugs affecting the QT interval before admission; 5) clinical signs of left ventricular failure or cardiogenic shock at admission or during the hospitalization; 6) development of severe ventricular arrhythmias after 24 hours from the onset of symptoms. Three subgroups were individuated : group A: 39 patients with non life-threatening ventricular arrhythmias; group B: 12 patients with episodes of ventricular tachycardia within the first 12 hours of myocardial infarction; group C: 15 patients with episodes of ventricular fibrillation within the first 12 hours of myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1983

Exercise induced ventricular arrhythmias. Angiographic correlation with the severity of coronary artery disease.

We correlated the incidence and degree of exercise induced ventricular arrhythmias (EIVA) with the angiographic severity of coronary artery disease (CAD) in 162 patients with a history of stable effort angina, all showing a positive exercise stress test for myocardial ischemia and a greater than or equal to 70% stenosis of a major coronary artery. Patients were grouped according to the following criteria: presence of electrocardiographic evidence of old transmural myocardial infarction (MI), number of significant coronary stenoses and number of left ventricular (LV) areas showing abnormal segmental wall motion (ASWM). The incidence of EIVA in patients with multivessel CAD was higher than in patients with single vessel CAD, but this difference was not statistically significant. The number of LV areas with ASWM was better correlated with the frequency of EIVA, which was 20.0% in patients with normal LV wall motion, 31.2% in patients with 1 area of ASWM, 54.0% in patients with 2 areas of ASWM (p less than 0.005 vs normal LV wall motion), 74.1% in patients with 3 or more areas of ASWM (p less than 0.001 vs normal LV wall motion and 1 area of ASWM), and 81.8% in patients with LV aneurysm (p less than 0.001 vs normal LV wall motion and 1 area of ASWM, p less than 0.005 vs 2 areas of ASWM). Patients with old MI showed a significantly higher incidence of EIVA than those without MI (p less than 0.001), but this difference was due to the more severe LV asynergy in the MI group. In conclusion, our results show that, in a selected population of patients with CAD, the incidence of EIVA correlates better with the extent of LV segmental wall motion abnormalities than with the number of diseased coronary arteries or the presence of an old transmural MI.

Adult↗
PubMed1983

Hemodynamics of the splanchnic and systemic circulation after hypotonic water load-comparison between normal subjects and patients with congestive heart failure.

The authors investigated the changes in cardiovascular and splanchnic hemodynamic, diuresis and urinary and hepatic veins osmolarity induced by hypotonic water load in five normal subjects and in five patients with congestive heart failure (CHF). Pulmonary wedge pressure increased significantly only in CHF patients while cardiac index, total pulmonary resistances and peripheral vascular resistances remained unchanged in both groups. Hepatic blood flow increased significantly in control group while in CHF showed a significant reduction 15 and 30 minutes after water load. Hepatic veins osmolarity decreased significantly in control group only at the 45th minute. Diuresis was significantly higher in normals which eliminated water load with a lower urinary osmolarity. The authors conclude that: water loading is particularly interesting in so much it resembles the physiological conditions of the absorption of the alimentary hypotonic bolus; the failing heart responds to the water load on a depressed function curve; the hepatic blood flow is reduced in CHF patients and is probably responsible for some humoral abnormalities found in these subjects; CHF patients eliminate a water load slower than a normal subject and with a higher osmolarity.

Aged↗
PubMed1983

[Effectiveness of the aorto-coronary by-pass procedure in elderly patients].

This study was undertaken to evaluate the efficacy of coronary artery by-pass grafting (CABG) in elderly patients with coronary artery disease. A consecutive series of 79 patients, 65 years of age and older, who underwent CABG from 1975 to 1981 was analysed and their follow up status ascertained. This group was compared with a consecutive series of 397 patients under the age of 65 who underwent CABG during the same period. The patients aged 65 years or greater had a higher incidence of unstable angina pectoris (p less than 0.05). Coronary angiographic and left ventriculographic features were comparable in both age groups; also comparable were the number of saphenous veins graft utilized and the number of left ventricular aneurysmectomies and mitral valve replacements performed. The hospital mortality rate for patients aged 65 years and older was 12.6%, for those aged less than 65, it was 8.3%; if the other cardiac procedures are excluded mortality rates become 12.5% and 6.0% respectively (n.s.). Survival at 6 years was 92% for patients in both age groups. However, the symptomatic status was less favourable in older patients, compared with that obtained in younger patients (p less than 0.05).

Aged↗
PubMed1982

The autonomic nervous tone abnormalities in the genesis of the impaired baroreflex responsiveness in borderline hypertensive subjects.

1. The effects of intravenous administration of neostigmine and propranolol, individually or in combination, on baroreflex responsiveness have been evaluated in 18 borderline hypertensive subjects and in 14 age-matched control subjects. 2. Baroreceptor sensitivity was tested by evaluating both heart rate response to phenylephrine-induced increase in arterial pressure, and heart rate and blood pressure changes induced by increasing neck-tissue pressure by means of a neck-chamber. 3. In borderline hypertensive subjects a reduced baroreflex responsiveness was demonstrated with both stimuli as compared with normal subjects. Neostigmine administration improved consistently both reflex responses. Similarly, after propranolol treatment, borderline hypertensive subjects showed a significant enhancement of the baroreflex sensitivity. Finally, the combined administration of neostigmine and propranolol restored the baroreflex responses. In fact, both the mean slopes of the regression lines between blood pressure and R-R interval after phenylephrine and the increase in mean arterial pressure and heart rate induced by the reduction in carotid transmural pressure in borderline hypertensive subjects were similar to those observed in normals. 4. These findings indicate that in borderline hypertensive subjects the impairment of baroreflex responsiveness is mainly due to abnormalities of autonomic regulation.

Adult↗
PubMed1982

Effects of oral salt loading on beta-adrenergic receptor responsiveness in normal and hypertensive subjects.

The effect of oral salt loading (400 mmol per day of NaCl for 7 days) on cardiac and pancreatic beta-receptor responsiveness has been evaluated in 12 patients with established essential hypertension and in seven age-matched control subjects. Cardiac beta-receptor responsiveness was evaluated by assessing the dose of isoprenaline which increased a stable heart rate by 25% (chronotropic dose 25%, CD 25%). Pancreatic beta-receptor responsiveness was measured by the incremental areas of insulin secretion induced by iv infusion of increasing amounts of isoprenaline. Before salt load, CD 25% was significantly higher in hypertensives compared with controls (7.84 +/- 1.34 micrograms vs 3.9 +/- 0.48 micrograms, P less than 0.05) while there was no difference in the isoprenaline-induced insulin secretion between the two groups of subjects. After salt loading, CD 25% was significantly reduced in hypertensive patients but was not modified in normal subjects. Therefore, the difference in CD 25% was no longer detectable between the two groups (5.5 +/- 1.42 micrograms vs 3.2 +/- 0.48 micrograms in normal subjects and in hypertensives, respectively, NS). Furthermore, salt loading failed to induce any change in isoprenaline-induced insulin secretion in either groups. These results support the existence of a relationship between sodium intake and adrenergic beta-receptor responsiveness in human hypertension.

Adolescent↗
PubMed1982

Renal function in borderline hypertensive first-degree relatives of essential hypertensives. Effects of sodium load.

Renal function in the basal state and after sodium load has been investigated in 21 borderline, hypertensive, first-degree relatives of established hypertensives and in 21 age- and sex-matched, normal subjects with no family history of hypertension. During intravenous infusion of inulin and p-aminohippurate in saline, both groups showed a decrease in plasma aldosterone levels (p less than 0.05) but renal plasma flow (595 +/- 48 vs. 750 +/- 59 ml/min, p less than 0.05), diuresis (1.4 +/- 0.2 vs. 2.2 +/- 0.5 ml/min, p less than 0.05), natriuresis (0.21 +/- 0.02 vs. 0.3 +/- 0.02 mEq/min, p less than 0.05) and sodium clearance (1.05 +/- 0.1 vs. 2.4 +/- 0.4 ml/min, p less than 0.05) in borderline hypertensives were higher than in the control group. After the salt load (NaCl, 1.35% i.v., 5 ml/min for 2 h) there was an increase in blood pressure and a decrease in plasma aldosterone and potassium levels in both groups. However, borderline hypertensives showed higher diuresis, natriuresis, sodium clearance and also kaliuresis compared to normotensives. These results suggest that borderline hypertensives already present the changes in renal function which are characteristics of established hypertensives.

Adolescent↗