Biomedical subjects

C Perrakis

Publications and source records attributed to C Perrakis.

4 recordsLinked to original sources

PubMed1987

The efficacy of propafenone on exercise-induced ventricular arrhythmias.

We studied the efficacy of propafenone in 16 patients (pts) with exercise-induced ventricular arrhythmias (VA). Propafenone was given in doses of 450 mg (13 pts) to 900 mg (3 pts) per day and was compared with placebo. An arrhythmic index was calculated by dividing the frequency and severity of VA by the duration of exercise test (in min). Propafenone reduced that VA index from 17.05 +/- 16.32 to 3.75 +/- 7.47 (P less than 0.005). In 8 pts the VA were completely abolished, and in 8/10 grade greater than or equal to 3 VA, while no significant change was seen with placebo. In 8 pts in whom exercise had been prematurely terminated because of significant VA, a longer duration was achieved with propafenone (from 4.19 +/- 2.74 to 9.39 +/- 1.63, P less than 0.02). In those with the same pre-planned duration, a smaller peak heart rate was seen with propafenone. Resting P-R was significantly prolonged.

Adult↗

PubMed1987

The influence of R-wave amplitude on the degree of ST-segment depression in exercise electrocardiography in the individual patient.

Many factors have been found to influence the magnitude of ST-segment depression in the exercise electrocardiogram. We investigated whether R-wave amplitude is a significant factor. We studied the exercise electrocardiogram of 20 patients with angiographically documented coronary artery disease, including greater than or equal to 70% stenosis of the left anterior descending artery, who had an ischemic response to exercise but no previous anterior myocardial infarction. Precordial leads V1-6 were taken into account. When all 120 leads were measured, those with ST-segment depression greater than or equal to 2.0mm at peak exercise had a mean resting R-wave amplitude of 19.03 +/- 5.81mm; those with ST-segment depression 2.0-1.0mm, R 11.42 +/- 5.99mm; and those with ST-segment depression less than 1.0mm, R 5.9 +/- 5.21mm (p less than 0.001 between groups). When the R-wave amplitude was correlated with the ST-segment depression in each precordial lead, the correlation was 1.0. In leads V1-6, when 67 tracings with ST-segment depression greater than 0.5mm were measured, the correlation was 0.537 (p less than 0.001). In each precordial lead the t values of R-wave differences correlated very strongly (r less than 0.883) with the differences in ST-segment depression. We conclude that precordial R-wave amplitude significantly influences the magnitude of ST-segment depression.

Coronary Disease↗

PubMed1986

The QS2/QT ratio as an index of appropriate left ventricular response to autonomic and inotropic stimuli.

Dissociation between duration of electrical and mechanical systole has been seen with increase of myocardial shortening velocity or adrenergic activity. We found a decrease of the QS2/QT ratio after exercise in 10 pts with semisitting bicycle maximal exercise test and a normal radionuclide angiogram. No change was seen in 9 patients with a normal study with beta blockade, and in pts with a abnormal radionuclide test, without beta blockade (11 pts). In 19 normal active individuals, a significant QS2/QT decrease (p less than 0.001) was seen after a submaximal exercise treadmill test, which was inhibited by beta blockade. We believe that QS2/QT diminution is suggestive of an increase of the inotropic state of the left ventricle with exercise, produced through adrenergic stimulation. It is not seen either when an ischemic left ventricle cannot adequately respond to exercise or after beta blockade.

Adult↗

PubMed1984

Cardiac function at treadmill exercise in various age groups.

We compared the response to a modified Bruce treadmill exercise (EX) protocol lasting 7 min in 5 groups of male individuals free of clinical heart disease: I (age less than 35 years, N = 12), II (age 35-44 years, N = 10), III (age 45-54 years, N = 13), IV (age 55-64 years, N = 13) and V (age greater than 65, mean 70.35 +/- 4.67 years, N = 20). The following data were compared: (a) Heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP); resting (R) and their % changes at pre-EX standing and at 3, 6, 7 min, immediately and 2 and 4 min after EX (where EX is a relatively low grade of exercise). (b) The R QS2/QT and PEP/LVET ratios and their % change immediately and 4 min after EX. Resting and peak SBP was higher in groups IV and V. The various groups responded in a similar way to EX. The only significant difference was that the older age group (V) showed on the whole an increase in DBP with EX while groups I-III showed a decrease and group IV no change. This finding may reflect a lesser diminution in vascular resistance with EX in old age. However, inotropic and chronotropic reserves appear similar to those of younger individuals.

Adult↗