Assessment of ventricular function with first-pass radionuclide angiography using technetium 99m hexakis-2-methoxyisobutylisonitrile: a European multicentre study.

In the context of a multicentre study on the use of technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-Sestamibi), we evaluated the accuracy of the ventricular function assessed at rest by means of first-pass radionuclide angiocardiography acquired during the injection of the tracer for myocardial perfusion scintigraphy. The results were compared with first-pass studies performed using reference tracers sodium pertechnetate Tc 99m or technetium 99m diethylene triamine penta-acetic acid or with gated radionuclide angiocardiography. A total of 66 patients of the 105 enrolled in the study could be evaluated. The comparison of the first-pass studies was possible in 33 subjects with regard to the left ventricular ejection fraction, yielding r = 0.909 (P less than 10(-6)), and in 22 cases with regard to the right ventricular ejection fraction, yielding r = 0.712 (P less than 0.001). The comparison between the first-pass study using 99mTc-Sestamibi and the equilibrium gated radionuclide angiocardiography was possible for the left ventricular ejection fraction in 26 cases, with r = 0.937 (P less than 10(-6)), and for the right ventricular ejection fraction in 15 subjects, with r = 0.783 (P less than 0.001). In conclusion, the assessment of ventricular function performed by acquiring a first-pass radionuclide angiocardiograph during the injection of 99mTc-Sestamibi for perfusion myocardial scintigraphy can be considered reliable and accurate, when compared with the usually employed techniques. This result confirms the feasibility of a combined evaluation of perfusion and function at rest and during stress testing, which represents one of the most interesting advantages offered by the use of 99mTc-Sestamibi.

Pathophysiologic assessment of left ventricular hypertrophy and strain in asymptomatic patients with essential hypertension.

To investigate the significance of the electrocardiographic (ECG) pattern of left ventricular hypertrophy and strain, two groups of asymptomatic patients with essential hypertension were compared. The patients were similar in terms of age, smoking habit, serum cholesterol and blood pressure levels, but differed in the presence (Group I, n = 23) or absence (Group II, n = 23) of the ECG pattern of left ventricular hypertrophy and strain. Group I patients had significantly more episodes of exercise-induced ST segment depression (14 versus 4, p less than 0.05) and reversible thallium perfusion abnormalities (11 of 23 versus 3 of 23, p less than 0.05) despite similar exercise capacity and absence of chest pain. Nonsustained ventricular tachycardia was detected on 24 h ambulatory ECG monitoring in two patients in Group I, but no patient in Group II. Coronary arteriography performed in 20 Group I patients demonstrated significant coronary artery disease in 8 patients. This study has shown that there is a subgroup of hypertensive patients with ECG left ventricular hypertrophy and strain who have covert coronary artery disease. This can be detected by thallium perfusion scintigraphy, and may contribute to the increased risk known to be associated with this ECG abnormality.

Arteriovenous shunting of microspheres in patients with colorectal liver metastases: errors in assessment due to free pertechnetate, and the effect of angiotensin II.

In patients receiving locoregional therapy for liver metastases degradable microspheres are being increasingly used in an attempt to improve cytotoxic delivery to the tumour. However, counterproductive arteriovenous shunting through the liver following intrahepatic arterial injection can occur, leading to deposition in the lung. Measurement of the degree of shunting is important in the monitoring of this kind of therapy. In this study we describe the use of technetium-labelled microspheres of serum albumin (99Tcm MSA) to measure baseline shunting during hepatic arterial perfusion scintigraphy in five patients with liver metastases of colorectal origin, and assess the significance of the values obtained for relative lung uptake (RLU) which we define as: RLU = Activity in lung field/Activity in liver + lung fields X 100%. We found that shunting was less than 5% in all cases, zero shunting occurring in 14 of the 16 patients studied. The sources of error in this technique have been assessed, the most important being the presence of free pertechnetate in the injectate. The use of Boots 10 ml vials and glass syringes respectively to dispense and administer this radiopharmaceutical reduces this error to a small predictable level. In our small group of patients, we found no evidence to suggest that use of the vasoactive agent angiotensin II significantly increases baseline shunting in patients with colorectal liver tumour.