George I. Thomas

Relation between middle cerebral artery blood flow velocity and stump pressure during carotid endarterectomy.

Background and Purpose: Many patient monitoring techniques have been used for detecting cerebral hypoperfusion during carotid endarterectomy. We compared middle cerebral artery blood flow velocities with carotid artery stump pressures to evaluate the indications for common carotid artery cross‐clamp shunting and the probable hemodynamic causes of cerebrovascular complications. Methods: Blood flow velocities were monitored with transcranial Doppler ultrasound and carotid stump pressures were measured at the time of common carotid artery cross‐clamping during 97 carotid endarterectomy procedures. Stump pressures measured with the gauge zero reference at the common carotid artery level were correlated with the percentage change of velocities. Results: Middle cerebral artery blood flow velocities usually decreased upon common carotid artery cross‐clamping, depending on collateral availability and the autoregulation response. The best fit of the data was to an exponential function concave to the pressure axis, with velocity as a percentage of the pre‐cross‐clamp value reaching zero at 15 mm Hg stump pressure (r=0.85 and p<0.001). Conclusions: There is a less critical margin of error with percentage middle cerebral artery blood flow velocity decreases than with stump pressure measurements. This relation establishes changes in middle cerebral artery blood flow velocities as a reliable parameter for judging the effects of carotid cross‐clamping on cerebral blood flow and providing an excellent indicator as to the necessity for shunting. (Stroke 1992;23:1439‐1445)

Large vessel appliqué arteriovenous shunt for hemodialysis. A new concept.

Summary A high-flow arteriovenous shunt has been developed which is attached to the common femoral artery and vein. This large vessel “applique” shunt resulted from the vexations of repeated cannulations in aging patients receiving dialysis using the standard peripheral arm or leg arteriovenous shunt. Thirty-nine patients have been operated on for a total of forty shunts and these patients have been followed up for from four to eighteen and a half months, with satisfactory results to date. Complications other than infection have been negligible and readily handled without rehospitalization and reoperation. Forty per cent of the patients are receiving anticoagulation therapy for repetitive minor shunt thromboses and heavy fibrin formation on the artificial kidney. Infection remains a serious problem and has caused the death of two patients. Further follow-up studies will ultimately make it possible to ascertain whether or not this concept, with continuing changes in the prosthesis, will be adequate for all patients. As it stands currently, it is a readily satisfactory back-up and support shunt when all other available shunt sites have been used. Acceptance by the patient of this femoral shunt, with its position, high-flow characteristics and ease of handling, is high.

The middle scalene muscle and its contribution to the thoracic outlet syndrome

The predisposing anatomic alterations or features of thoracic outlet syndrome have been tallied to better define this difficult and inchoate issue. In the last 34 supraclavicular operations involving 33 patients (for a total operative experience of 128 procedures), we have found the anterior insertion of the middle scalene muscle to be present in 48 percent of our patients. This insertion, forward on the first rib, closes an already small interscalene triangle, so that the posteriorly placed brachial plexus is entrapped or irritated by the anterior edge of this muscle, which may be very sharp and firm. In addition, 10 percent of our patients had a middle scalene band intimately associated with the middle scalene muscle, often-times inseparable, for a 58 percent incidence of middle scalene involvement in the thoracic outlet syndrome. With data such as those presented herein, a more simplified operation than the heretofore popular all-out attack on the first rib may well be in the offering.

Noninvasive carotid bifurcation mapping: Its relation to carotid surgery

Abstract The carotid bifurcation can be studied accurately by a noninvasive Doppler mapping procedure. Areas of plaquing and stenosis can be located and flow patterns and alterations in velocity can be assessed equally. The technic described is valuable in many clinical settings to aid in the detection and prevention of potential stroke. It is not designed to subordinate standard cerebral angiography but to complement it. The Doppler carotid survey is easy to perform, reliable in its reproducibility, and designed to detect not only morphologic changes but also functional abnormalities of blood flow.

The St. Jude experience

This paper covers our experience with the use of the St. Jude prosthetic heart valve from November 1979 through August 1983 in 91 patients operated on for aortic and mitral valve replacement. Nonfatal complications included hemorrhagic sequela due to anticoagulation, with an annual rate of 1 percent (1.4 percent per 100 patient years), thromboembolism with an annual rate of 0.8 percent (0.87 percent per 100 patient years), sternal infection 1 percent, operative cardiovascular accident 1 percent, and pericardial tamponade 1 percent. Operative mortality was 1 percent, early mortality (within 30 days) was 3 percent, and late mortality was 3 percent, with a total overall mortality of 7 percent. Excluding two patients who died from noncardiac causes, the overall mortality was 5 percent. The mortality rate per year was 2 percent. The survival rate 3.8 years postoperatively was 89 percent for mitral valve replacement patients and 93 percent for aortic valve replacement patients, for an overall 38 year survival rate of 92 percent. All patients were anticoagulated with warfarin. There were no instances of valve failure, replacement, or serious hemolysis. Eighty-three percent were active or working with a New York heart functional class I. In our experience, the complication rate with the St. Jude valve is as low or lower than that for any other mechanical prosthetic cardiac valve available in the world today.

Coincident bilateral chylothorax and chylous ascites

T HE problems of chylothorax and chyIous ascites, whether of traumatic or nontraumatic origin, are unusual in the lives of most physicians. Apparently, however, these conditions are increasing in frequency due to automobiIe injuries, on the one hand, and to new surgica1 operations in the region of the thoracic duct, on the other hand. In recent decades various investigators have been abIe to describe and cIassify various types and etiologies of these manifestations of disease. Others have made significant contributions in the therapy of these diffrcuIt probIems. Some cases, however, remain df obscure origin and are resistant to modern methods of treatment. The foIlowing is a report of such a case. It was referred to by Loe in his discussion of Brewer’s paper, but has not been reported in detai1 before [I]. The onIy other remarkabIe item in the history was the presence of an edematous Ieft hand and forearm since birth which was otherwise normal in deveIopment and function. He was admitted to the King County HospitaI on December 14, 1954. Physical examination reveaIed that the bIood pressure was 125/85 mm. Hg; puIse, 80; respirations, 20: and temperature, 98.6%. The head, eyes, ears, nose and throat were negative for abnormaIities. The thyroid was norma in size and consistency and there were no masses or nodes. The chest was barreI-shaped. There was duIIness to percussion posteriorIy on the right and to the IeveI of the fifth rib, and less high on the Ieft. Breath sounds in these areas were very distant. Examination of the heart reveaIed no abnormalities. The abdomen was markedIy protuberant, with diastasis recti and fluid wave present. No organs or masses were noted, and there was no tenderness. Recta1 examination was negative and the genitalia were normal.

Obstructive Lesions Diagnosed by Doppler Ultrasound

Doppler ultrasound examinations occupy a needed position between simple office screening techniques and more costly and invasive procedure of x-ray arteriography. Doppler supplements arteriography by providing functional information not provided by x-ray and serving as a screening procedure to clarify the need for arteriography and surgery. This chapter is intended as a catalogue of obstructive lesions which are surgically correctable or when present with other’ surgical’ obstructions can be assessed with Doppler to plan the surgical approach.