Thallium-201 myocardial imaging during pharmacologic coronary vasodilation: comparison of oral and intravenous administration of dipyridamole.

Although the diagnostic utility of thallium-201 myocardial imaging after dipyridamole infusion is well established, the intravenous form of the drug is not yet commercially available in North America. Fifty patients referred for coronary angiography were prospectively studied. Within a 2 week period, each patient underwent cardiac catheterization and thallium-201 myocardial imaging after both oral and intravenous dipyridamole administration. For the oral protocol, patients were randomly assigned to treatment with either 200 or 400 mg of dipyridamole in tablet form. Coronary artery stenoses of 70% or greater were considered significant. For the 25 patients who received a 200 mg oral dose of dipyridamole, the scintigraphic study showed perfusion defects in 65% of patients with significant coronary artery disease after the oral dose and in 85% of patients after the intravenous dose. For the 25 patients who received a 400 mg oral dose, the sensitivity of the scintigram was 84% after the oral dose and 79% after the intravenous dose. Except for headache and nausea, side effects were less severe and less frequent with oral (either 200 or 400 mg) than with intravenous dipyridamole. Because of the delayed and variable absorption of dipyridamole tablets, the oral studies required a longer period of medical supervision (45 to 60 minutes), and aminophylline was empirically administered after completion of the first set of thallium-201 images. It is concluded from this study that thallium-201 myocardial imaging after coronary vasodilation with a 400 mg oral dose of dipyridamole is a safe, widely available and reliable alternative for the evaluation of coronary artery disease in patients unable to achieve an adequate exercise level on stress testing.

Unusual echocardiographic findings in a patient with left atrial myxoma.

A 53-year-old patient is presented who had left atrial myxoma with unusual echocardiographic findings. The patient had been regarded for 10 years as having mitral stenosis. This error in diagnosis was due in part to misinterpretation of his echocardiograms. This report is presented to emphasize not only the unusual echocardiographic findings but also the subtle findings on the phonocardiogram and apexcardiogram which should have led to the correct diagnosis.

Further echocardiographic observations in pericardial effusion.

Although the presence of fluid behind the left atrium, on echocardiography, has been used to differentiate pleural from pericardial effusions, five cases are reported showing that pericardial fluid can and does accumulate behind the left atrium. Abnormal valvular motion, as a result of free swinging of the heart in the pericardial sac, was also demonstrated in these patients.

Control of cancer-related pain with MS Contin: a comparison between 12-hourly and 8-hourly administration.

Nineteen cancer patients with chronic pain of moderate to severe intensity were randomized in a double-blind manner to 5 days of either 8-hourly or 12-hourly administration of controlled-release morphine (MS Contin, MSC), followed by the alternate schedule for 5 days. The control of pain, using an average dose of 303.4 +/- 254.4 mg/day of MSC, was good during both the 8-hourly and 12-hourly phases, and the mean daily pain intensity measured by visual analogue scale (VAS), pain relief (VAS), and global efficacy scores did not differ when compared by treatment schedule. The need for supplemental "rescue" morphine was infrequent and did not differ between treatment phases (8-hourly, 0.7 +/- 0.7 and 12-hourly, 0.6 +/- 0.6 doses per day, p = 0.6232). The overall frequency and severity of adverse events did not differ between the two dosing schedules. A majority of patients (67%) reported that they believed that 12-hourly dosing was a moderate or great advantage over 8-hourly dosing.

Change in amplitude distributions of Doppler spectrograms recorded below the aortic valve in patients with a valvular aortic stenosis.

Amplitude distributions of Doppler spectrograms were characterized in a group of 22 patients having no aortic pressure gradient and another group of 26 patients having a stenotic aortic valve. Specifically, for each patient, the ratios of the mean amplitude in three normalized frequency bands (low, middle and high) to the mean amplitude of the Doppler spectrogram computed in selected portions of the systolic period were considered. Pulsed-wave Doppler spectrograms were recorded by positioning the sample volume in the left ventricular outflow tract, approximately 1 cm below the aortic valve. Statistically significant differences were found between the middle (p = 0.041) and high (p = 0.028) frequency bands of Doppler signals recorded from the two groups of patients. The differences observed are believed to be attributed to blood flow eddies generated below the stenotic aortic heart valve and to changes in blood flow orientation.

Computer evaluation of Doppler spectral envelope area in patients having a valvular aortic stenosis.

The reliability of three algorithms to estimate the maximal and minimal frequency contours of Doppler spectrograms was evaluated in a group of 48 patients. Two algorithms had previously been used in the literature. These are the Modified Threshold Crossing Method and the Hybrid method. The third algorithm is new and is the Maximal Background Noise Threshold Crossing Method. A new approach was also proposed in the present study to estimate the background noise level of Doppler spectrograms. This level was used as a threshold in the computation of the spectral envelopes. Two diagnostic spectral parameters (the spectral envelope area and the systolic velocity integral) extracted from Doppler spectrograms recorded in the left ventricular outflow tract were also evaluated and tested to discriminate between 23 patients having no aortic pressure gradient and 25 patients with a stenotic aortic valve. Results describe the influence of the threshold level used in the Modified Threshold Crossing Method and the Hybrid method on the variability of the spectral contours. It is clearly demonstrated that the variability of minimal frequency contours is higher than that of maximal frequency contours. All three algorithms provided similar diagnostic performances with the spectral envelope area (71% to 73% of correct classifications) while the Maximal Background Noise Threshold Crossing Method and the Hybrid method provided the best results for the systolic velocity integral (69% of correct classifications). Because the systolic velocity integral combined with the continuity equation is used in the literature to evaluate noninvasively the aortic valve area, these results suggest the use of the spectral envelope area instead of the systolic velocity integral.

Echocardiographic measurements and plasma levels of atrial natriuretic factor.

Atrial distension and pressure have been reported to be important for the release of atrial natriuretic factor (ANF) into the circulation. However, in mild essential hypertension, we have been unable to demonstrate an increase in plasma levels of ANF. To evaluate more precisely the lack of increase of ANF, we measured echocardiographically the diameters of the cardiac chambers and correlated these measurements with ANF values in normal subjects (n = 25), in patients with untreated essential hypertension (n = 20), and in patients with treated essential hypertension (n x 27). The plasma values of ANF were 21.9 +/- 2.8 pg/ml in the normal controls, 20.4 +/- 2.2 pg/ml in patients with untreated mild essential hypertension, and 32.6 +/- 2.8 pg/ml in patients with treated but uncontrolled essential hypertension (p less than 0.05). The plasma values of cGMP were 4.53 +/- 0.56 pmol/ml in the normal, 5.41 +/- 0.57 pmol/min in the patients with untreated essential hypertension, and 6.76 +/- 0.58 pmol/ml in treated essential hypertension (p less than 0.05). There were no significant differences in the size of the cardiac chambers between the three groups, except for the size of the right atrium, but there was a correlation between the ANF values and the size of the left atria (r = 0.29, p = 0.01, n = 72), as well as with the size of the intraventricular septum (IVS) in systole (r = 0.36, p = 0.002, n = 72). Since ANF levels are similar in mild untreated essential hypertension and normal volunteers, the ANF plasma levels could be a better reflection of the impact of the blood pressure on the myocardium than the level of blood pressure itself and indicate in patients the degree of cardiac impairment. On the other hand, there seems to be definitely an effect of treatment on the levels of ANF.

Mitral stenosis obscuring the diagnosis of plexogenic pulmonary arteriopathy and familial pulmonary hypertension.

A patient who died after surgery for critical mitral stenosis was found to have underlying unrecognised plexogenic pulmonary arteriopathy and familial pulmonary hypertension. The importance of recognising familial pulmonary hypertension is discussed, together with the contribution of genetic and other risk factors to plexogenic pulmonary arteriopathy.