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Biomedical subjects

M Spadafora

Publications and source records attributed to M Spadafora.

16 recordsLinked to original sources
PubMed1991

Diastolic perfusion time at ischemic threshold in patients with stress-induced ischemia.

BACKGROUND: To evaluate the relevance of diastolic perfusion time on the mechanisms underlying stress-induced ischemia, 16 patients with coronary artery disease and seven patients with syndrome X underwent five randomized stress tests (upright and supine exercise with and without therapy, transesophageal atrial pacing). METHODS AND RESULTS: Exercise duration Time to 0.1 mV ST segment depression, heart rate, rate-pressure product, and diastolic perfusion time were evaluated for each patient during stress tests. In both groups, variability coefficients of the above-mentioned parameters were not different at rest. At ischemic threshold (0.1 mV ST segment depression) in patients with coronary artery disease, the variability coefficient of exercise duration (40.1 +/- 22.2) was significantly higher (p less than 0.0001) than those of heart rate (12.8 +/- 2.9), rate-pressure product (14.8 +/- 3.3), and diastolic perfusion time (0.39 +/- 0.1). The variability coefficient of diastolic perfusion time was also significantly (p less than 0.0001) lower than those of heart rate and rate-pressure product. Similarly, the variability coefficient of diastolic perfusion time (0.44 +/- 0.1) in syndrome X patients was significantly lower (p less than 0.0001) than those of exercise duration (28.2 +/- 9.4), heart rate (12 +/- 1.4), and rate-pressure product (14.6 +/- 1.3). CONCLUSIONS: Fixed diastolic perfusion time at ischemic threshold, despite different kinds of stress tests and variability of heart rate and rate-pressure product, indicates the relevant role of diastolic perfusion time in determining myocardial ischemia.

Adult↗
PubMed1991

Diastolic time at ischemic threshold in patients with syndrome X.

The patients with so-called syndrome X experience true myocardial ischaemia in spite of their anatomically normal coronary arteries. The pathogenetic mechanism of the effort-induced ischaemia in these patients should be obviously different from that of patients with atherosclerotic coronary artery lesions. An inadequate coronary dilatory capacity in response to increased oxygen demand has been proposed as mechanism responsible of ischaemic response to effort (Canon et al., 1983; Canon et al., 1985). Since diastolic duration expressed as percentage of the cardiac cycle has implications with the myocardial oxygen demand/supply ratio (Boudoulas et al., 1982; Maseri et al., 1977), the purpose of this study has been to evaluate the behaviour of this parameter at the outcome of the ischaemic electrocardiographic changes during stress testing in the patients with syndrome X.

Adult↗
PubMed1990

Exercise-induced impairment of diastolic time in patients with X syndrome.

Since an abnormal shortening of diastolic duration during exercise in the patients with coronary artery disease was demonstrated, time course of diastolic period (cardiac cycle minus electromechanical systole) calculated from polycardiographic recording has been assessed in patients with X syndrome and in normal age-matched subjects during supine ergometer exercise. All patients with X syndrome had positive exercise stress response (more than 0.1 mV of ST segment depression). Duration of diastole expressed as percent of cardiac cycle was significantly shorter at the intermediate steps and at the peak of exercise in patients with X syndrome compared with normal subjects (p less than 0.05). When the relationship between heart rate and diastolic time was examined, an inverse nonlinear regression was found both in normal subjects and in patients with X syndrome. The exercise values of diastolic time observed in patients with X syndrome were significantly shorter than those predicted as normal diastolic time heart rate relation. Thus the patients with X syndrome demonstrated abnormalities in the decrement of diastolic time with exercise. We hypothesized that this disproportionate shortening, by reducing subendocardial blood flow, might induce a worsening of ischemic response to exercise.

Angina Pectoris↗
PubMed1990

Alinidine in chronic stable angina: the effect on diastolic perfusion time.

The present study has been performed to assess the effects of alinidine on diastolic duration during exercise in chronic coronary artery disease. Twelve male patients with stable effort angina and without previous myocardial infarction were studied. They received alinidine or placebo in a double-blind randomized crossover trial for 3 days after a wash-out period of 4 days. Alinidine was administered at a dosage of 30 mg 3 times a day. At the end of each treatment the patients underwent upright bicycle exercise. Left ventricular time intervals were obtained by means of carotid thermistor plethysmography. Diastolic duration was calculated by subtracting the electromechanical systole from the R-R interval and expressed as a percentage of the cardiac cycle (%D). Alinidine increased both total exercise duration from 246.7 +/- 120.7 to 346.6 +/- 114.1 s (p less than 0.05) and time to 0.1-mV ST segment depression from 98.3 +/- 53 to 187.2 +/- 105 s (p less than 0.05). Similarly the drug induced a reduction of the rate-pressure product and of the extent of ischemic ST segment depression during exercise. %D was increased by alinidine both at rest and during exercise. A direct linear regression between R-R and %D was found after both alinidine and placebo treatments either at rest or during exercise. Nevertheless, no difference was observed between both slopes and intercepts. Therefore, since the relationship between R-R interval and %D was unaffected by alinidine, it was possible to hypothesize that the changes in diastolic duration were due only to the bradycardic action of the drug.

Angina Pectoris↗
PubMed1989

Non-invasive assessment of left ventricular performance in patients with coronary artery disease after chronic diltiazem therapy.

To evaluate the effects of diltiazem (240 mg/day) on the left ventricular function, we studied 13 patients with coronary artery disease (CAD). Comparison with placebo was made in a double-blind randomized crossover study. Both placebo and diltiazem were administered for 5 weeks. We assumed left ventricular systolic time intervals assessed by polycardiography as parameter of ventricular function. Diltiazem induced a significant decrease in pre-ejection period (p less than 0.01) as well as pre-ejection period/left ventricular ejection time ratio (p less than 0.01). Thus, our results suggest that diltiazem improves the contractile state of ischemic myocardium in CAD patients.

Blood Flow Velocity↗
PubMed1988

Electromechanical events during spontaneous angina.

The electromechanical events occurring during acute myocardial ischemia were assessed in 10 patients who developed spontaneous angina during cardiac catheterization. Aortic pressure and electrocardiogram were recorded, and heart rate and systolic and diastolic time intervals were measured under control conditions, at the onset of angina and during the relief of chest pain. In 5 patients spontaneous angina was accompanied by an increase in heart rate and systemic arterial pressure and by ST segment changes in anterior or anterolateral precordial leads. Diastolic time, expressed as percent of cardiac cycle, shortened from 48.8 +/- 3.6% at rest to 33.6 +/- 4.8% (p less than 0.01) at the onset of angina, as a consequence of a significant increase in both electromechanical systole and heart rate, and returned to control values within 10 min after sublingual nitroglycerin. In the remaining 5 patients, spontaneous angina was accompanied by a decrease in heart rate and systemic arterial pressure and by ST segment changes in the inferior or inferolateral leads. The diastolic time increased significantly (p less than 0.05) from 39.4 +/- 6.1% at rest to 47.8 +/- 9% at the onset of angina, as a consequence of a significant decrease in heart rate and a slight decrease in electromechanical systole. Since coronary perfusion takes place mainly during diastole, our results suggest that the reflex increase in adrenergic tone may worsen myocardial ischemia by affecting diastolic perfusion time. In contrast, the increase in vagal tone may contribute to spontaneous relief of angina by prolonging diastolic perfusion time.

Adult↗
PubMed1988

[Influence of posture on exercise-induced electrocardiographic and hemodynamic changes in patients with stable effort angina pectoris].

The present work was performed in order to assess the differences in electrocardiographic and hemodynamic responses to supine and upright dynamic exercise of patients with coronary artery disease. Changes in heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure, rate-pressure product (RPP) and ST segment depression during supine and upright bicycle stress test were compared in twenty patients suffering from stable effort angina and without previous myocardial infarction. In the supine posture lower values of HR were observed at rest, during stress test and during three minutes of the recovery period. Conversely, in all patients both SBP and DBP were higher during the stress test in the supine position decubitus. No significant changes in RPP was observed between the two different postures. Finally, ST segment didn't show differences at rest between the upright and supine position. All the patients had a lower ischemic threshold during exercise in the supine position than in the upright one. In fact an ST segment depression greater than 1 mm was observed during stress test in the supine position at lower work-load levels and at lesser HR values. Consequently for given HR, SBP and DBP ST segment, depression was greater in the supine rather than in the upright position.

Adult↗
PubMed1986

Perceived credibility of a "neutral" abortion-related message and its sponsor.

This study investigated the effect of a high- versus low-credibility sponsor on the perceived credibility of an abortion-related message. Three groups of subjects read a message that had been evaluated as "neutral" by officials of both "pro-life" and "pro-choice" groups. Sponsorship of the message was varied among the three groups (no sponsor; pro-life sponsor; pro-choice sponsor). Subjects rated the credibility of the message and credibility of the sponsor and also indicated their own attitudes toward abortion. Pro-life and pro-choice subjects did not differ in their perception of the nonsponsored message. The signature of a high-credibility sponsor improved the message's perceived credibility; however, the signature of a low-credibility sponsor did not diminish the message's credibility.

Abortion, Induced↗
PubMed1978

Evaluation of cardiac arrests managed by paramedics.

The effectiveness of cardiac resuscitations by Cincinnati paramedics was monitored for one year. The outcome of every arrest was assigned to one of four categories: dead on arrival, died in the emergency department, died in the hospital or discharged alive, and each patient was followed until death or discharge from a hospital. Of the 147 people in the study group, 22 left the hospital alive, a long-term success rate of 15%, and another 26 died during hospitalization, 18% of the study population. This data is comparable to success rates reported by other prehospital care systems. Furthermore, this data indicates approximately 15% of people who have cardiac arrests outside of a hospital can survive through prompt intervention by trained personnel.

Adolescent↗