A sensor for needle puncture force measurement during interventional radiological procedures

Computer-based simulation for interventional radiology training has attracted increasing attention in recent years because of its potential to train remotely from patients and to provide objective assessment of proficiency. Yet developing a high fidelity simulator with realistic tactile feedback requires accurate knowledge of forces exerted on medical devices during interventional radiology procedures. This paper presents the development and validation of a force sensor for the measurement of axial forces generated during needle, and combined cannula/trocar, puncture procedures in patients. In order to assess the performance of this sensor, in vitro measurements were obtained using needle penetration of porcine liver, kidney and muscle. The results were compared with forces measured by means of a tensile tester.Calibration results showed that the force sensor has high sensitivity and linearity. Comparison of the force profiles obtained from the sensor and the tensile tester shows that good agreement was achieved in the in vitro studies for all the tissues tested.Preliminary clinical force measurements during arterial puncture and liver biopsy procedures have been performed in patients. An example of force recording for each procedure type is presented.     

Prognosis of left anterior hemiblock in acute myocardial infarction

Four of 32 patients with left anterior hemiblock and an acute anterior wall myocardial infarction died. Left anterior hemiblock was present on admission in 24 patients, and subsequently appeared in 8. Of the 28 survivors, 21 are still alive an average of 2.8 years after the acute myocardial infarction.     

Noninvasive assessment of coronary stenoses by myocardial imaging during pharmacologic coronary vasodilatation. III. Clinical trial

Thallium-201 myocardial imaging was performed at rest, after maximal treadmill exercise and during coronary vasodilatation induced by the intravenous administration of dipyridamole in 62 patients undergoing coronary angiography. Myocardial images after dipyridamole infusion were compared with rest and exercise thallium-201 images to determine the utility of pharmacologic stress for detecting coronary artery disease. Dipyridamole, 0.142 mg/min, was infused for 4 minutes with electrocardiographic and blood pressure monitoring, and thallium-201 was injected intravenously 4 minutes after infusion.Myocardial/background count ratios of 2.3 ± 0.5 (mean ± 1 standard deviation) after the administration of dipyridamole were higher than similar ratios for exercise images (2.1 ± 0.5; P < 0.001). The sensitivity of thallium-201 imaging for detecting significant coronary artery disease was equal for dipyridamole and exercise stress. In 51 patients with a 50 percent or greater stenosis of one or more coronary arteries, image defects were identified in 34 of 51 (67 percent) exercise and dipyridamole images. Twenty of 51 patients (39 percent) had abnormal rest images; in 17 of 20 patients, new or increased image defects were present after exercise and the infusion of dipyridamole. One of 11 patients (9 percent) with no stenosis of 50 percent or greater had a defect on exercise and dipyridamole images. Six of seven patients with new or enlarged image defects after the intravenous administration of dipyridamole also had new or enlarged defects after the oral administration of dipyridamole.After the infusion of dipyridamole, the heart rate increased from 64 ±10 beats/min supine to 88 ± 13 beats/min standing (P < 0.001), and blood pressure decreased from $\text{129 ±}\text{16}\text{80}\text{± 9}\text{to}\text{120 ±}\text{17}\text{75}\text{± 9}\text{mm Hg}\text{(P < 0.001)}$. Angina and S-T depression occurred more frequently with exercise than with dipyridamole. S-T depression occurred in only two patients (3 percent) with dipyridamole, suggesting that diagnostic images were often obtained without significant ischemia. This study demonstrates that pharmacologic coronary vasodilatation is as effective as maximal treadmill exercise in creating myocardial perfusion abnormalities detectable with thallium-201 imaging in man.     

Growth hormone causes rapid induction of lactogenic receptor activity in the Snell dwarf mouse liver.

The Snell dwarf mouse (dw/dw) has no detectable PRL-binding sites in the microsomal fractions of its liver. Both bGH and bPRL, purified by preparative gel electrophoresis, induce PRL-binding sites when injected into dw/dw. Intraperitoneal injection of 100 micrograms bGH every 8 h results in the appearance of a high affinity PRL receptor 8--16 h after initiation of treatment. This induced binding capacity plateaus after 32 h of treatment and subsequently decreases to nondetectable levels 48 h after the last injection. [125I]Iodo-ovine PRL is displaced from the induced receptor equally well by similar concentrations of ovine PRL, human GH, and bovine PRL, but is displaced by bovine GH (bGH) only at approximately 100-fold higher concentrations. While untreated dw/dw livers do possess high affinity bGH-binding sites, treatment with bGH did not alter the bGH-binding activity. Treatment of dw/dw with cycloheximide does not prevent induction of PRL receptors by bGH injections. These observations indicate that bGH induces the PRL receptor by interacting with the cell at some point distal to the induced receptor site and does not require the synthesis of new proteins.