Obstruction to blood flow through the internal carotid artery invokes collateral blood supply from the Circle of Willis and from reversal of flow in the ophthalmic artery. These collateral pathways serve to ameliorate the effects of the restricted carotid blood flow. In addition they provide a simple means by which the diagnosis of carotid obstruction may be suspected. Using a Doppler ultrasonic velocity detector, flow in these vessels may be examined and the presence or absence of functioning collateral pathways may be determined. The technique for this examination has been developed over a period of years and has proved to be a reliable method of screening for significant carotid obstruction.

A new Doppler ultrasonic imaging technique for mapping the course of arterial channels has been applied to the carotid bifurcation in over 800 patients. The technique has proven its ability to detect stroke producing wall disease including calcified plaques and flow disturbances. (Stroke 5:145, 1974) Comparisons with x-ray angiography demonstrates agreement in 89

In patients with occlusion of the common carotid artery, the external carotid artery is often kept open by collateral flow through the superior thyroid and lingual branches. If there is no surgically correctable lesion in the opposite carotid vessels, revascularization of the external carotid artery can provide a sufficient increase in collateral blood flow to relieve symptoms of cerebrovascular insufficiency. In three patients with occlusion of the common carotid artery, subclavian-external carotid artery bypass grafts were inserted. Each patient exhibited clinical improvement during follow-up periods ranging from twenty to forty-two months.

Experiences with 450 transseptal left heart catheterizations are reviewed. There were no mortalities in this series, and the only significant complication was accidental puncture of the aorta in three patients. The equipment and technic employed in the current method, by which a radiopaque catheter of large caliber is introduced into the left ventricle, are described in detail. The advantages of this modification are outlined.

A technic for performing selective left atrial and left ventricular angiocardiography by means of percutaneous transseptal left heart catheterization is described and the results of such studies performed in sixty patients are presented. The clinical applications of this technic in the study of patients with various forms of obstruction to left ventricular outflow, various types of mitral valve lesions, defects of the ventricular septum and anomalies of the aortic arch are discussed in detail.

Experiences with left heart pressure measurements in 111 infants and children are reviewed. These studies were performed by means of transseptal left heart catheterization or anterior percutaneous left ventricular puncture. The only significant complication was the development of left pneumothorax in two patients following the latter procedure. The techniques are briefly described, and the importance of left heart catheterization in the clinical management of infants and children with heart disease is illustrated by means of selected clinical examples.

Patients with persistent partial atrioventricular canal and only small interatrial communications may present the clinical features of pure mitral regurgitation. Two such individuals, who on clinical examination were mistakenly considered to have rheumatic mitral regurgitation, are described. The roentgenographic findings supported this diagnosis, and the electrocardiograms did not exhibit the vector loop characteristic of an endocardial cushion defect. Cardiac catheterization made possible the correct diagnosis, however, and at operation each patient was found to have a cleft anterior mitral leaflet and an unusually small interatrial defect of the ostium primum type. Problems which relate to the diagnosis and surgical management of this unusual variant of persistent A-V canal are discussed.

The acute hemodynamic effects of 0.50 to 0.75 mg. ouabain were studied in six patients with valvular aortic stenosis and in four patients with idiopathic hypertrophic subaortic stenosis. Left atrial and left ventricular pressures were determined by means of transseptal left heart catheterization and cardiac output was measured by the indicator-dilution technic. In the patients with valvular aortic stenosis, ouabain either improved left ventricular function or had no discernible effect on it, but in no patient was left ventricular function depressed. Left ventricular end-diastolic pressure fell slightly or remained unchanged, while cardiac output rose in two of four patients. In the patients with hypertrophic subaortic stenosis, the left ventricular end-diastolic pressure and mean left atrial pressure rose significantly following ouabain administration; cardiac output either fell or remained unchanged and the systolic pressure gradient between the left ventricle and the brachial artery rose. These actions of ouabain in hypertrophic subaortic stenosis are considered to result from a sustained increase in left ventricular contractile force that increased the obstruction produced by the muscular outflow tract.

When krypton85 in saline solution is injected into the left side of the heart and sampled from a systemic artery, or is injected into a peripheral vein and sampled from the pulmonary artery, only the primary time-concentration curve is obtained. Recirculation is eliminated by the diffusion of this indicator into the extravascular space and its loss from the pulmonary capillary bed. Determination of the radioactivity in a single blood sample, withdrawn at a constant rate throughout the period during which the Kr85 passes across. the sampling site, permits calculation of the average concentration of Kr85 during the inscription of the primary curve. The validity of this technique was tested in a circulatory model against actual flow determined by timed collection. One standard deviation of the differences in 27 trials equaled 5.1 per cent. In 26 comparisons of cardiac output determined simultaneously in dogs by a rotameter and the Kr85 technique, one standard deviation of the differences equaled 8.4 per cent. In 19 comparisons of cardiac output in patients, determined by dye-dilution and Kr85 techniques, one standard deviation of the differences equaled 11 per cent. The Kr85 technique is simpler technically and requires less blood, instrumentation, and calculation than the standard dye techniques.

Left heart catheterization has become an increasingly important method for the pre-operative assessment of patients with congenital or acquired heart disease, and in recent years a variety of techniques have been introduced for gaining access to the left atrium and left ventricle (Morrow et al., 1960).When the usual clinical examinations indicate the need for such study the physician must select the method of left heart catheterization that will provide the information, in a particular patient, with a minimum of risk and discomfort.One of the techniques most commonly employed for access to the left ventricle is anterior percutaneous puncture.Although this method has been widely used since it was described and popularized by Brock and co-workers in 1956, relatively little information is available concerning experiences with this technique (Fleming et al., 1958; and Raynaud et al., 1959).At the National Heart Institute left ventricular puncture has been employed in the course of 226 haemodynamic studies.The present report constitutes a description of the techniques and a summary of the experience with the procedure in this clinic.TECHNIQUE Left ventricular puncture is performed only in the operating room or cardiac catheterization laboratory.Systemic arterial pressure and the electrocardiogram are continuously monitored throughout the study.Equipment for internal and external cardiac defibrillation is immediately available and a surgeon experienced in the techniques of resuscitation is present.Adult patients are given pentobarbital 100 mg., orally, one hour before the procedure.Children usually receive a combination of meperidine, phenergan, and promazine, which is supplemented during the catheteri- zation, if necessary, with light general anesthesia.With the patient in the supine position the proposed site of puncture is selected.In most patients the apical approach is preferred.The skin and chest wall over the apical impulse are liberally infiltrated with a local anxsthetic agent down to the pleura.A 20 gauge needle, 10 cm. in length, is attached to the three-way stopcock on the end of a Statham P23D pressure transducer.The side arm of the stopcock permits the injection of saline and indicator solutions during the pro- cedure.The baseline or zero point for the pressure recording is determined with the needle and gauge held in the position in which the puncture will be made.As the electrocardiogram and the pressure at the needle tip are continuously observed on a cathode-ray oscilloscope, the needle is advanced through the chest wall and directed toward the second right intercostal space in a 643 on August 21,

Transseptal left heart catheterizations were carried out in 18 patients without apparent evidence of organic cardiovascular disease. These studies have permitted delineation of the pressures that exist in the left side of the heart in normal subjects studied in a basal physiologic state.

In the presence of valvular aortic stenosis or of discrete subvalvular stenosis, the narrowed orifice is constant and its size is not altered by changes in the force of ventricular contraction. In hypertrophic subaortic stenosis the orifice narrows during systolic contraction of the hypertrophied muscle in the left ventricular outflow tract and the orifice size therefore is a function of the force of left ventricular contraction. In 75 patients, proved to have the discrete, "fixed" type of aortic or subaortic stenosis the beats following the compensatory pause after a premature contraction were always characterized by higher left ventricular systolic pressures and larger systemic arterial pulse pressures than the normal beats, i.e., arterial pulse pressure varied directly with left ventricular systolic pressure and with the duration of diastole. In 12 patients proved to have hypertrophic subaortic stenosis, the beats following premature contractions always exhibited lower arterial pulse pressures than did the normal beats, i.e., arterial pulse pressure varied inversely with left ventricular systolic pressure and with the duration of diastole. The distinction between these two types of obstruction to left ventricular outflow may be established with confidence by this analysis of the effects of premature ventricular contractions on either the simultaneously recorded left ventricular and arterial pressure pulses, or on the arterial pressure pulses alone. The recognition of hypertrophic subaortic stenosis is essential in formulating a rational plan of treatment for all patients with obstruction to left ventricular outflow, and the hemodynamic technic described affords a simple but reliable diagnostic approach.

A technic is described for introducing a radiopaque catheter into the left heart through the interatrial septum. The chief advantages of the method are that selective left atrial and ventricular angiocardiography may be conveniently performed in conjunction with transseptal left heart catheterization and that surgical exposure of the saphenous vein is not necessary.