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Biomedical subjects

M Papouchado

Publications and source records attributed to M Papouchado.

At least 37 records · Page 2Linked to original sources
PubMed1988

Direct Fick cardiac output: are assumed values of oxygen consumption acceptable?

The use of assumed values of oxygen consumption has become an accepted practice in the calculation of direct Fick cardiac output. A survey showed that the assumed values in common use were derived from basal metabolic rate studies on normal subjects, a use which may not be valid. We have compared previous assumed values based on basal metabolic rate or cardiac catheterization studies with those obtained by direct measurement in 80 patients (age range 38-78 years) with various cardiac disorders. Comparison of the assumed and directly measured values of indexed oxygen consumption and the cardiac index showed large discrepancies, with over half the values differing by more than +/- 10% and many by more than +/- 25% from the measured value. Assumed values of oxygen consumption should be used with caution when calculating cardiac output during cardiac catheterization procedures, because large errors can result. The equations of LaFarge and Miettinen gave the closest approximation to the measured data and their use is recommended in preference to values predicted from basal metabolic rate studies.

Adult↗
PubMed1987

Assessment of percutaneous transluminal coronary angioplasty with 123IODO-heptadecanoic acid.

Ten patients underwent myocardial scintigraphy with 123I-iodo-heptadecanoic acid (HDA), which was injected in the last minute of maximal exercise testing. Six of the patients were rescanned following percutaneous transluminal coronary angioplasty. All ten patients underwent full coronary angiography. There were visible perfusion defects on the static images in 74% of the myocardial areas which were supplied by an artery with a stenosis greater than 75%. The mean half life recorded from areas distal to an arterial stenosis of at least 90% (35.69 min +/- 41.25 min), was longer than the expected normal mean (18.85 min +/- 3.35 min). However, the difference was not statistically significant. The static images changed in some patients following angioplasty, however there was no consistent alteration in the half lives. It was concluded that HDA is a suitable agent for investigating myocardial perfusion, but that the half life cannot be measured adequately for clinical purposes with a planar imaging system.

Angioplasty, Balloon↗
PubMed1987

Prognostic value of 123-IODO-heptadecanoic acid imaging in patients with acute myocardial infarction.

This trial aimed to test if the half life of radioiodinated heptadecanoic acid (HDA) in acutely infarcted myocardium is of prognostic value. Twenty patients had an HDA scan and a MUGA scan within 6 days of acute myocardial infarction, eighteen of these had a visible defect on the HDA images. The mean half life of the areas of acute infarction (15.50 min +/- 7.82 min) was significantly shorter than that of normal myocardium (20.77 min +/- 4.00 min). The MUGA scan was repeated after 6 months in 15 patients. The mean acute infarct half life was longer in patients with an LVEF improvement of at least 5% at 6 months (16.92 min +/- 10.56 min), compared to those with a deterioration of more than 5% (11.75 min +/- 4.03 min), although the difference is not statistically significant. While the results in a few individuals suggested that the half life may be of prognostic significance, the variable response of the group reduced the ability of the half life to act as a prognostic indicator. Improvements in imaging and background subtraction techniques may be necessary before the half life is of practical value.

Clinical Trials as Topic↗
PubMed1987

Fundamental differences between the standard 12-lead electrocardiograph and the modified (Mason-Likar) exercise lead system.

A comparison of the standard 12-lead electrocardiograph with the Mason-Likar lead system widely used for exercise stress testing shows that the two are not 'essentially identical' as was originally claimed. Placement of the limb electrodes onto the torso distorts the electrocardiograph causing a rightward shift of the mean QRS axis, a significant reduction in R-wave amplitude in leads I and aVL, and a significant increase in R-wave amplitude in leads II, III and aVF; the R-wave amplitude of the chest leads is also altered. The so-called 'inferior' leads on the exercise electrocardiography are probably modified anterior/inferior leads, since their R-wave amplitudes correlate closely with those of antero-lateral chest leads. The inferior surface of the heart is not represented in isolation on the exercise electrocardiograph, thus explaining the reported inability of the exercise test to predict the location of coronary artery disease and high incidence of false negative tests in patients with ischaemia limited to the inferior cardiac surface.

Coronary Disease↗
PubMed1987

Towards improved control of atrial fibrillation.

Patients with atrial fibrillation frequently show a wide variation in heart rate with digoxin therapy. We have compared the effect on heart rate variability, of doubling the digoxin dosage or adding verapamil 120 mg daily in a randomized cross-over study in 14 patients. Twenty-four hour ambulatory electrocardiographic recordings, six minute walking tests and palpitation and breathlessness scores were obtained on each regime. All patients exhibited a diurnal pattern in heart rate variability. Both treatments significantly lowered heart rate but high dose digoxin lowered minimum heart rate significantly more than digoxin and verapamil, causing more night time bradycardia. Overall, digoxin with verapamil produced significantly less heart rate variability than digoxin alone. Day time but not night time pauses were prolonged by digoxin and verapamil but were prolonged more by high dose digoxin. Five (36%) patients had serum digoxin levels in the toxic range when taking high dose digoxin. Palpitations were significantly reduced by both treatments but most improvement occurred with digoxin and verapamil. No significant effect was found on six minute walking distances or breathlessness scores. In conclusion, the addition of verapamil to digoxin was superior to increasing the dose of digoxin alone, producing significantly better control of heart rate variability with less night time bradycardia.

Aged↗
PubMed1987

Simple anatomical basis for surface electrocardiographic changes during selective coronary arteriography.

The relationship between surface electrocardiographic changes during selective coronary arteriography and coronary artery anatomy was examined in 185 consecutive patients. When both major arteries were patent, two distinct patterns of electrocardiographic changes occurred. Electrocardiogram leads reflecting the areas supplied by the injected vessels showed a change we have termed the 'perfusion response', while electrocardiogram leads reflecting regions not supplied by the injected vessel simultaneously showed a pattern we have termed the 'reciprocal response'. These changes were reproducible on serial injections, and occurred whether or not coronary artery or valvular heart disease was present. A third type of electrocardiographic change--termed a 'biphasic response' and comprising a reciprocal followed by a perfusion response--was observed in leads reflecting a collateral-dependent region of viable myocardium. This response was seen in the inferior surface leads with left coronary artery injection when the right coronary artery was occluded, but not in leads I and aVL with right coronary artery injection when a branch of the left coronary artery was occluded, where chest leads may be needed for its detection. The biphasic response was also seen in the inferior leads with left coronary artery injection in patients in whom this artery was dominant. Thus, the distribution of electrocardiographic changes during arteriography is dependent on native coronary artery anatomy, collateral vessels and myocardial viability. Changes relate to the site of coronary lesions only where vessels are occluded, but may be of practical value when the viability of (and thus suitability for bypass grafting to) a myocardial region is in doubt.

Contrast Media↗
PubMed1987

Failure of a negative exercise test to reassure patients with chest pain.

Seventy-two patients with chest pain and negative exercise tests were observed. Twenty-one (29 per cent) became pain free but 51 (71 per cent) continued to complain of chest pain. Patients with persistent pain were significantly more anxious and depressed at presentation and later compared with those who had become pain free. Anxiety and particularly depression, at presentation and later, were significantly associated with severe symptoms. Patients with chest pain associated with neurosis and depression are not reassured by physiological stress testing because their physical symptoms are a feature of underlying psychiatric disease.

Adult↗
PubMed1986

Combined therapy with disopyramide and amiodarone: a report of 11 cases.

Combined amiodarone and disopyramide therapy is generally believed to be potentially harmful. We report 11 patients who have received this combination, none of whom have experienced any serious adverse reactions. In addition, 9 of the 11 patients derived marked clinical benefit. This combination deserves further evaluation as an anti-arrhythmia therapy.

Adult↗
PubMed1986

Ventricular pacing improves exercise tolerance in patients with chronic heart block.

Exercise capacity was assessed by means of a simple six minute walking test in a group of 18 patients with heart block whose only presenting symptom was breathlessness. None was in overt cardiac failure. Patients were studied before and after implantation of a transvenous, ventricular, demand pacing system (study group). Eight patients with an implanted pacemaker admitted for elective generator replacement were assessed in the same manner (control group). Exercise capacity in the study group was significantly increased within 48 hours of pacing, and this improvement was maintained in most patients during the follow up period of up to 30 months. In contrast, exercise capacity was unaffected by generator replacement in the control group. Simple ventricular pacing produces symptomatic benefit in patients with heart block accompanied by breathlessness. This benefit is apparent within 48 hours of pacing and is maintained; it can be assessed objectively by a six minute walking test.

Aged↗
PubMed1985

Anxiety and depression in patients with chest pain referred for exercise testing.

Anxiety and depression were measured in 87 consecutive patients (65 males, 22 females) with chest pain before diagnostic exercise treadmill testing. Chest pain was assessed as typical or atypical of angina by an independent observer. Fifty exercise tests were positive; thirty-seven were negative (including nineteen submaximal). Patients with negative tests had significantly higher scores for anxiety and higher depression scores than those with positive tests. 12% of patients with positive tests were women compared with 43% with negative tests. 27 patients (73%) with negative tests had atypical pain compared with 6 (12%) with positive tests. Depressed patients walked for a significantly shorter time. The probability of a negative test in patients without anxiety or depression who had typical pain was 8% in males and 32% in females; the probability of a negative test in patients who were both anxious and depressed and had atypical pain was 97% in males and 99% in females. Diagnostic exercise testing in patients with both affective symptoms and atypical chest pain may be unhelpful, misleading, and uneconomical.

Adult↗