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Biomedical subjects

F Rengo

Publications and source records attributed to F Rengo.

At least 19 recordsLinked to original sources
PubMed1992

Effect of beta-adrenoceptor blockade on dipyridamole-induced myocardial asynergies in coronary artery disease.

Twenty-one patients with angiographic evidence of significant coronary artery disease, and positive dipyridamole echocardiographic test results at basal condition and after 7 days of placebo treatment were prospectively studied to see whether beta blockade modifies the effects of dipyridamole echocardiographic testing on regional myocardial contractility. Patients were randomized to propranolol (120 mg/day) or placebo treatment in 3 divided doses for 7 days, after which each patient crossed over to the alternate regimen. Dipyridamole-echocardiographic testing was repeated at the end of each treatment. Propranolol abolished new mechanical signs of transient dipyridamole-induced ischemia (new wall motion abnormalities or an increase in degree of basal asynergies, or both) in 13 of 21 patients. The remaining 8 patients had positive results on dipyridamole echocardiographic testing after the propranolol treatment period. At basal conditions both heart rate and rate-pressure product were significantly reduced with propranolol; there was also a significant decrease in these parameters at peak dipyridamole infusion. At peak dipyridamole infusion heart rate and rate-pressure product were significantly lower in patients with negative than in those with positive echocardiographic test results after propranolol. Our data show that administration of beta blockade significantly reduces the development of transient dipyridamole-induced myocardial asynergies, the earliest markers of acute myocardial ischemia, detected with 2-dimensional echocardiography.

Adrenergic beta-Antagonists↗
PubMed1992

Age-related effects of ischemia, lidocaine and verapamil on overdrive-induced suppression of ventricular pacemakers in isolated rat heart.

The effect of age on ventricular automaticity in the isolated perfused rat heart was determined under different conditions. When the ventricle is electrically stimulated at a faster rate, drive cessation is followed by a temporary suppression of ventricular automaticity (overdrive suppression). The effects of ischemia, lidocaine and verapamil on overdrive suppression were studied in isolated perfused adult and senescent rat hearts with complete atrio-ventricular block, by monitoring ventricular escape rate and escape rhythm recovery time after 1 minute of overdrive at a constant multiple (x3) of the spontaneous rate. The results demonstrated that: 1) lidocaine decreases ventricular automaticity especially in senescent hearts; 2) verapamil does not modify ventricular automaticity in basal conditions in either adult or senescent hearts; 3) myocardial ischemia causes a reduction in ventricular automaticity and more markedly in senescent hearts; and 4) lidocaine exaggerates the effect of ischemia, while verapamil seems to antagonize its depressant effect more in adult than in senescent hearts.

Aging↗
PubMed1992

Age-related effects of platelet activating factor (PAF) in the isolated perfused rat heart.

Platelet Activating Factor (PAF) is a phospholipid that has been implicated as an important mediator of anaphylactic cardiac dysfunction and involved in the toxic effects of the ischaemia-reperfusion process. In the elderly, these phenomena are thought to be exaggerated by the age-related changes in response to several chemical factors and myocardial ischaemia. We evaluated the effects of PAF (acetyl-o-alkyl-l-phosphatidylcholine) on left ventricular systolic (LVSP) and diastolic (LVDP) pressure, coronary flow rate (CFR) and heart rate (HR) in adult (6 months, AH) and senescent (24 months, SH) rat hearts. The perfusion of PAF (10(-8), 10(-7) and 10(-6) M) induced a concentration-related reduction of LVSP, CFR and HR and a linear increase in LVDP. Contractile modifications were more pronounced in senescent hearts: LVSP decreased (P < 0.01) and LVDP increased with respect to younger animals (P < 0.01 vs. AH). This negative inotropic effect was also present in electrically paced hearts. PAF produced conduction arrhythmias ranging from second-degree atrio-ventricular conduction block to cardiac standstill both in adult and senescent hearts; at a higher dose (10(-6) M), cardiac standstill appeared after 96.5 +/- 15.3 s in adult hearts and after 45.5 +/- 17.6 s in senescent hearts (P < 0.01). Lyso-PAF did not modify while specific PAF antagonist compounds CV-3988 inhibited all electromechanical responses both in adult and senescent hearts. These data suggest that age influences the effect of PAF on contractile parameters, coronary flow and conduction arrhythmias by acting on receptors, whose function is unaffected by age.

Aging↗
PubMed1992

Early manifestations of dementing illness: treatment with glycosaminoglycan polysulfate.

1. In a multicenter, placebo-controlled, double-blind clinical trial in 156 elderly patients with psychopathologic symptoms, glycosaminoglycan polysulfate was found to be a therapeutically effective agent in the treatment of the earliest manifestations of a dementing process. 2. Treatment with glycosaminoglycan polysulfate in the daily dosage of 600 LRU, administered on the basis of a divided dosage schedule for 24 weeks, was significantly superior to an inactive placebo on several outcome measures including the SCAG Total and factor scores (i.e., Cognitive Dysfunction, Withdrawal, Agitation/Irritability and Depression), the NOWLIS Total and Fatiguability factor scores, the MMSE, the HAM-D Total and Vegetative Symptoms factor score and the CGI Severity of Illness and Global Improvement. 3. The drug was well tolerated; vital signs and laboratory measures did not show clinically significant changes within the experimental period.

Affect↗
PubMed1992

Controlled study on the therapeutic efficacy of propionyl-L-carnitine in patients with congestive heart failure.

A double-blind phase II study of propionyl-L-carnitine (CAS 17298-37-2) versus placebo was carried out on a group of 60 patients with mild to moderate (II and III NYHA class) congestive heart failure. The group was made up of men and women aged between 48 and 73 years in chronic treatment with digitalis and diuretics for at least 3 months and who still displayed symptoms. Thirty of these patients were chosen randomly and for 180 days, 500 mg of propionyl-L-carnitine was orally administered, 3 times a day in addition to their usual treatment. At basal conditions and after 30, 90 and 180 days the maximum exercise time was evaluated using an exercise tolerance test performed on an ergometer bicycle and the left ventricular ejection fraction was tested by means of bidimensional echocardiography. After one month of treatment, the patients treated with propionyl-L-carnitine, compared to the control group, showed significant increases in the values of both tests, increases which became even more evident after 90 and 180 days. At the stated times the increases in the maximum exercise time were 16.4%, 22.9%, and 25.9%, respectively. The ventricular ejection fraction increased by 8.4%, 11.6% and 13.6%, respectively. On the basis of these results, having studied the particular mechanism of action of propionyl-L-carnitine the authors conclude that it represents a drug of undoubted therapeutic interest in patients with congestive heart failure, in whom it could be efficaciously administered along with a standard pharmacological therapy.

Aged↗
PubMed1992

Evaluation of the therapeutic efficacy and tolerability of levocarnitine propionyl in the treatment of chronic obstructive arteriopathies of the lower extremities: a multicentre controlled study vs. placebo.

The treatment of symptomatic chronic obstructive peripheral arteriopathies is a difficult task since it requires the prolonged administration of drugs which are often unable to correct the various pathogenetic factors reponsible for the disability. The authors, on the basis of recent studies demonstrating the rheological and vasoactive as well as metabolic activities of levocarnitine propionyl, have decided to use this substance in the treatment of arteriopathics affected by intermittent claudication. Levocarnitine propionyl administered orally to 142 arteriopathics affected by intermittent claudication was responsible for a marked increase in initial as well as absolute walking distances. It is particularly important to note that these clinical results were obtained primarily due to the metabolic activities of levocarnitine propionyl.

Administration, Oral↗
PubMed1991

Exercise induced increase in diastolic blood pressure. Is it an indicator of coronary artery disease?

It has been previously reported that an increase in diastolic blood pressure greater than 15 mmHg comparing values at rest with those on treadmill exercise, with or without ST changes, enhances the probability of coronary artery disease. To investigate whether the diastolic blood pressure variation keeps its diagnostic value during upright bicycle exercise, we evaluated the diastolic blood pressure variations in 111 patients with angiographically documented coronary artery disease without previous myocardial infarction and in 53 patients with normal coronary arteries undergoing maximal stress testing on a bicycle ergometer. The sensitivity of diastolic blood pressure (DBP) variations to detect coronary artery disease was 66%, the specificity 32%, the positive predictive value 67%, the negative predictive value 31% and the predictive accuracy 55%. The respective values for ST depression were 83% (P less than 0.001 vs DBP variations), 53% (P less than 0.05 vs DBP variations), 64% (P less than 0.05 vs DBP variations) and 75% (P less than 0.001 vs DBP variations). Forty-nine of the 75 patients with multivessel coronary artery disease and 60 of the 89 patients without coronary artery disease or with single vessel disease had abnormal DBP variations (sensitivity 65; specificity 33%). The sensitivity of ST segment depression in predicting multivessel disease was 91% (P less than 0.001 vs DBP variations), and the specificity 42%. Thus, for bicycle ergometer exercise testing, ST segment depression seems to be more accurate than DBP variations in the diagnosis of coronary artery disease.

Adult↗
PubMed1991

Effects of intracoronary gallopamil on coronary hemodynamics and myocardial oxygen consumption in humans.

The response of coronary hemodynamics to the intracoronary (i.c.) bolus administration of gallopamil, 1.5 and 3.0 micrograms/kg, was evaluated in 14 patients with normal coronary arteries. Gallopamil, 3.0 micrograms/kg, induced a small and transient decrease in systolic and mean arterial pressure and a small increase in the preejection period. Coronary sinus blood flow increased significantly at 30 s (p less than 0.01) and returned to baseline 10 min after gallopamil administration. Coronary vascular resistance was still reduced at 10 min and returned to baseline at 15 min. Myocardial O2 consumption and extraction decreased significantly (p less than 0.01) at 30 s. While myocardial O2 consumption returned to baseline 15 min after gallopamil administration, myocardial O2 extraction was still significantly reduced at this time. Milder and more transient changes were observed after i.c. administration of the lower dose (1.5 micrograms/kg), and no significant changes were found after i.c. administration of saline. These data show that i.c. gallopamil, in patients with normal coronary arteries, induces direct, transient, and dose-related peripheral coronary vasodilation. The reduction of myocardial O2 consumption and extraction suggests a direct negative inotropic and metabolic effect of gallopamil.

Adult↗
PubMed1991

Mechanisms of lidocaine actions on normal and abnormal rhythms in canine cardiac tissues in vivo and in vitro.

1. The actions of lidocaine on cardiac pacemaker rhythms were studied in anaesthetized dogs and in Purkinje fibres from hearts of the same animals. 2. In vivo, lidocaine (1 mg/kg, intravenously) slowed the sino-atrial (SA) node rhythm (-5.0%), and (during vagal stimulation) prolonged ventricular standstill by +25.1% and slowed the idioventricular rhythm (-16.7%). A higher dose (4 mg/kg) had more pronounced effects. 3. Propranolol also slowed sinus (-26.2%) and idioventricular (-27.2%) rhythms, and prolonged ventricular standstill (+36.8%). In the presence of propranolol, the effects of lidocaine on idioventricular rhythm were exaggerated. 4. In Purkinje fibres driven in vitro, lidocaine (10 mumol/L) decreased contractile force (-47.9%) and (during the interruption of drive) prolonged the suppression of (+53.2%) and slowed the escape rhythm (-67.0%). 5. In the presence of lidocaine the threshold potential was shifted to less negative values and diastolic depolarization slope was decreased (-23.6%). 6. Lidocaine slowed spontaneously active Purkinje fibres, abolished early afterdepolarizations in low [K]o and slow responses in high [K]o (by shifting the threshold to less negative values), and antagonized strophanthidin arrhythmias. 7. TTX reduced the hyperpolarization by lidocaine in low [K]o and vice versa. 8. We conclude that lidocaine enhances vagally-induced ventricular standstill by depressing the idioventricular rhythm far more than the sinus rhythm, an action enhanced by beta-blockade. Furthermore, lidocaine depresses normal and different types of abnormal automaticity through direct and indirect effects of the blockade of the fast sodium channel.

Animals↗
PubMed1991

Dipyridamole echocardiography as a useful and safe test in the assessment of coronary artery disease in the elderly.

We prospectively studied the sensitivity, specificity, feasibility, and safety of high-dose dipyridamole echocardiography, compared to exercise electrocardiography in 130 subjects (67 younger and 63 elderly patients) referred for angiographic evaluation of suspected or proven coronary artery disease. Sensitivity, specificity, and feasibility of dipyridamole echocardiography were respectively 75.5%, 100%, and 88.0% in younger patients and 82.9%, 100%, and 79.4% in elderly patients (P = NS). The sensitivity of exercise electrocardiography was 72.7% in young and 66.6% in elderly patients (P = NS); specificity 66.0% vs 60.0% (P = NS); feasibility 83.6 vs 63.5 (P = 0.05). Forty-nine younger and 38 elderly patients performed both tests. Sensitivity of dipyridamole echocardiography compared to exercise electrocardiography was 76.2% vs 73.8% in young patients and 83.3% vs 70% in the older group (P = NS). The feasibility of the two tests was significantly different in the elderly group only (dipyridamole echocardiography 79.4% vs exercise electrocardiography 63.5%; P less than 0.01). The incidence of side effects during dipyridamole echocardiography was similar in the two groups, except for dyspnea which was observed in 20% of older and 5% of younger patients (P less than 0.05). Our data demonstrate that the dipyridamole test combined with echocardiographic monitoring of regional myocardial contractility may be considered a valid non-invasive method for evaluating coronary artery disease in the elderly and that this test is a satisfactory alternative to the exercise stress test.

Aged↗
PubMed1991

The hypothetical role of potassium conductance on the genesis of R-wave amplitude increase during ischemia in the isolated rat heart.

The effect of increased potassium conductance on the genesis of R-wave amplitude increase during acute myocardial ischemia has been studied in the isolated perfused rat heart by simultaneously recording the R-wave amplitude of epicardial electrograms (VEE), heart rate (HR), coronary flow rate (CFR), left ventricular diastolic pressure (LVDP), and left ventricular systolic pressure (LVSP). The experiments were performed during basal and partial or total ischemic conditions at spontaneous or fixed HR. In some experiments, potassium conductance was increased by means of high-calcium (8 mM) or acetylcholine chloride (10(-6) M) perfusion. In the control experiments, partial ischemic perfusion produced an increase in VEE and LVDP and a decrease in HR, CFR, and LVSP; total ischemic perfusion exaggerated these variations. High-calcium perfusion provoked an increase in VEE and LVDP and a decrease in HR, CFR, and LVSP during basal conditions (p less than 0.01 vs. control experiment); these modifications increased progressively during partial ischemic perfusion (p less than 0.01 vs. control experiment) and during total ischemic perfusion (p less than 0.01 vs. control experiment). Perfusion with acetylcholine chloride produced variations similar to those observed in high-calcium solution except that LVDP under basal conditions remained unchanged from control. When the HR was maintained at a constant value by means of atrial pacing the results were similar to those observed in the unpaced hearts. In conclusion, in the isolated perfused rat heart, increasing potassium conductance may influence the genesis of R-wave amplitude increasing during acute myocardial ischemia.

Acetylcholine↗
PubMed1991

[Aging and left ventricular diastolic function].

Several studies have demonstrated that physiological aging significantly affects cardiovascular function. Experimental researches, conducted on cardiac muscle of senescent animals, have shown a prolongation of both contraction and relaxation times. This phenomenon was explained by a reduced Ca(++)-stimulated ATPase pump activity, responsible for the reduced sarcoplasmic reticulum Ca++ uptake rate. The myofilament response to Ca++ in the aging heart is normal as are peak contractile force production and post-extrasystolic twitch potentiation during continual paired stimulation. On the other hand, the inotropic response to cardiac glycosides and beta-adrenoceptor stimulation is diminished in senescent compared to adult myocardium. This decreased contractility could result mainly from mechanisms controlling Ca++ reuptake from sarcoplasmic reticulum and relaxation time (diastolic phase) rather than those determining force generation and contraction time (systolic phase). Age-related physiologic structural changes are not associated with significant variations in left ventricular diastolic and systolic sizes, but they seem a direct consequence of the rising systolic blood pressure observed in these age decades. Myocardial hypertrophy should not be considered a specific marker of the senescent heart, but rather an adaptive response to increased afterload conditions. As regard the relationship between age and diastole, it is important to underline that the alterations in aging cardiac muscle function primarily involve the isovolumic relaxation time and diastolic phase. With age, the early diastolic phase declines while the contribution of atrial contraction to ventricular diastolic filling increases as well as the isovolumic relaxation time.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

[The clinico-instrumental evaluation of the efficacy of picotamide in treating chronic obstructive arteriopathies of the lower extremities].

In 25 patients (19 males and 6 females) suffering from chronic arteriopathy of lower extremities at Fontaine stage II, the clinical efficacy of picotamide was investigated in double blind, cross over placebo-controlled study. Patients were assigned randomly to the treatment with placebo or picotamide (900 mg/die) for three months and, after 15 days of wash-out, to the treatment with picotamide or placebo for the same period. Painfree walking distance and ankle/arm systolic pressure ratio improved significantly only during picotamide treatment. Laboratory monitoring revealed a significant decrease in platelet aggregation and an increase of fibrinogen degradation products only during picotamide treatment. Three patients during picotamide treatment referred transient gastrointestinal discomfort (nausea, vomiting and diarrhoea); however in no case the treatment was suspended because of the appearance of these symptoms. These results indicate that picotamide is an effective drug in the management of chronic arteriopathy of lower extremities.

Aged↗
PubMed1990

Acute effects of nisoldipine, propranolol, and their combination in patients with chronic stable angina: a double-blind, randomized, cross-over, placebo-controlled study.

We studied the short-term effects of oral administration of nisoldipine (10 mg) and propranolol (80 mg) alone and in combination in 14 patients with chronic exertional angina pectoris in a double-blind, randomized, cross-over study. The 14 patients (13 men and 1 woman, mean age 56 +/- 7 years) performed symptoms-limited bicycle exercise stress test 3 h after placebo or active substance administration. Maximal work load, exercise duration, and time to 1-mm ST segment depression were significantly increased and ST depression at peak exercise was significantly decreased by drugs alone and in combination. Propranolol and nisoldipine alone improved exercise duration similarly and as well as the combination; however, a different response to the three pharmacologic interventions was found in patients treated with single drugs. The improvement in exercise tolerance was associated with rate-pressure product values at peak exercise, unchanged after nisoldipine and significantly reduced after both propranolol alone and in combination. After placebo, all patients had exercise-induced angina, in 9, 8, and 4 patients after nisoldipine, propranolol, and the combination of the two drugs, respectively. Nisoldipine is effective in the treatment of effort angina and its combination with propranolol may be useful and superior in patients who show poor response to monotherapy.

Aged↗
PubMed1990

[The effects of slow-release verapamil in relation to plasma concentration in aged hypertensives. A study with continuous monitoring of arterial pressure and electrocardiogram].

Twenty-four hour ambulatory blood pressure and electrocardiographic monitoring (Oxford method) was carried out in baseline conditions and after 15 days of therapy with a once a day administration of 240 mg verapamil slow-release in 11 elderly hypertensive patients. The 24 hour electrocardiographic monitoring (but not the blood pressure monitoring) was also carried out after 30 days of therapy. High-pressure liquid chromatography plasma concentrations of verapamil and its metabolite norverapamil were compared with the blood pressure and electrocardiographic responses. Systolic and diastolic blood pressure were significantly reduced after 15 days of therapy without circadian rhythm modification; mean heart rate was reduced after 15 and 30 days and the P-Q interval prolonged. Peak verapamil and norverapamil plasma concentrations were observed 8 hours after administration; at the 25th hour, the concentrations were respectively 60.9% and 68.3% of peak value (139.5 +/- 95.4 ng/ml and 126.4 +/- 60.9 ng/ml). Plasma levels of verapamil and norverapamil significantly correlated with heart-rate decrease. No correlation was observed between drug concentrations and systolic and diastolic blood pressure. A first-degree atrioventricular block was observed in 3 patients during therapy. Supraventricular premature contractions showed a decrease after 15 and 30 days of therapy. Thus, once a day administration of verapamil slow release is an effective anti-hypertensive medication in elderly hypertensive patients. Caution should be exercised in patients with P-Q interval prolongation and sinus bradycardia.

Aged↗