Large-bore, long biliary endoprostheses (biliary stents) for improved drainage.

Seventy-one large-bore, long biliary stents were placed in 62 patients. The 12-Fr Teflon stents with multiple side holes were made to extend from the entrance point of the biliary tree to the wall of the duodenum opposite the ampulla of Vater. The entire procedure takes one week. The techniques for placement and proper fashioning of the stents are described in detail. In one patient, the biliary tree was re-entered 15 months after the initial placement of a stent. The stent was removed percutaneously and replaced by a longer stent. The technique for removal is also described. The problems of migration and obstruction have been overcome with this technique, making this the preferred method of nonsurgical drainage of malignant obstructive jaundice.

Radionuclide analysis of ejection time, peak ejection rate, and time to peak ejection rate: response to supine bicycle exercise in normal subjects and in patients with coronary heart disease.

Using equilibrium radionuclide angiography, we evaluated the ejection time (ET), peak ejection rate (PER), and time to peak ejection rate (TTp) at test and during supine bicycle exercise in 39 subjects, divided into three groups: group 1 = 13 normal subjects; group 2 = 10 patients with a previous infarction (MI); and group 3 = 16 patients with coronary disease without a previous MI. Normal subjects had greater ejection fractions and PERs than the other two groups at rest or peak exercise (p less than 0.05). PER was no more useful than ejection fraction in identifying cardiac dysfunction at either rest or exercise. The time of its occurrence varied with the group studied, and was slightly but significantly later in systole in groups 2 and 3 when compared to normals (p less than 0.05), though substantial overlap between groups occurred. During exercise, absolute ET shortened in all groups, but actually increased as a function of the R-R interval. The time to peak ejection rate (normalized for the R-R interval) was greater in the noninfarct group (group 3) patients (p less than 0.05) when compared to the group 1 or group 2 individuals at peak exercise. In conclusion, equilibrium radionuclide angiography is a useful technique for the quantification and characterization of events during systole, and is capable of providing information on the timing of events during ejection. Tardokinesis, or the delay of ventricular ejection, is not seen in the response of global indices of left ventricular function to exercise stress. While global early systolic indexes may not detect regional dyssynchrony, their timing during stress may occasionally aid in discerning the presence of cardiac dysfunction.

Effects of acute incremental volume overload on cardiac chamber size, function, and the pulmonary circulation: analysis by digital intravenous angiography.

To assess the effects of acute incremental volume overload on cardiac size, function, and the pulmonary circulation, we studied six anesthetized dogs using intravenous digital angiography. Aortocaval (AC) fistulas were placed in four dogs, and fistulas in both a carotid and iliac artery were placed in two dogs. Data were obtained at four points: (1) control stage; (2) partial shunt (PS, where either AC partially open or iliac fistula was open and carotid fistula was closed); (3) full shunt (FS, AC shunt open or both iliac and carotid shunts open); and (4) control stage 2. Little change in heart rate (HR) or arterial pressure occurred. With FS, both mean pulmonary artery and wedge pressures increased (p less than 0.05); however, systemic and pulmonary vascular resistances declined. Cardiac output rose (1.54 +/- 0.42 L/min at control) to 2.44 +/- 0.84 L/min at PC (P less than 0.05 vs control) and to 3.13 +/- 0.89 L/min at full shunt (p less than 0.01 vs control). Both left (0.40 +/- 0.09 to 0.55 +/- 0.10 to 0.66 +/- 0.10, p less than 0.05 and p less than 0.01 vs control, respectively) and right (0.34 +/- 0.10 to 0.40 +/- 0.10 to 0.51 +/- 0.09, the latter p less than 0.01 vs control) ventricular ejection fractions rose, as did left (30.7 +/- 13 ml to 35.1 +/- 13 ml to 37.8 +/- 13 ml, the latter p less than 0.05 vs control) and right (37.4 +/- 6.1 ml to 44.2 +/- 16.6 ml to 51.4 +/- 17 ml, the latter p less than 0.01 vs control) ventricular end-diastolic volumes. Atrial volume (determined at ventricular end-systole) also increased (9.4 +/- 3.6 ml to 11 +/- 3.5 ml to 12.9 +/- 4.3 ml, the latter p less than 0.05 vs control). These increases in cardiac function and size occurred in association with a shortening of pulmonary transit time (5.4 +/- 0.8 to 3.5 +/- 0.7 seconds to 2.9 +/- 0.5 seconds, the latter two p less than 0.05 and p less than 0.01 vs control, respectively), with no significant change in pulmonary blood volume. We conclude that acute volume overload produces cardiac chamber dilatation, along with increases in systolic function. Both pulmonary and systemic vascular resistance declined, and the transit time in the pulmonary circulation shortened. Digital intravenous ventriculography is a useful technique for the analysis of the central circulation during acute hemodynamic manipulations.

A comparison of peak-to-peak pulmonary transit time determined by digital intravenous angiography with standard dye-dilution techniques in anesthetized dogs.

To evaluate the relationship between mean pulmonary transit time and peak-to-peak transit time by digital intravenous angiography six dogs were assessed during either isoproterenol or phenylephrine infusion. Acutely anesthetized dogs were instrumented with catheters in the pulmonary artery, left atrium, and carotid artery. An injection catheter was placed in the inferior vena cava, and contrast injections were made with a power injector (30 cc/second for 1 second of Renografin 76). Peak-to-peak transit times (pulmonary artery-left atrial time) were derived from videodensitometric time-absorption curves. Mean transit time was calculated from the usual optical densitometric analyses of green dye injected first in the pulmonary artery and then in the left atrium (sampled in a carotid artery). Peak-to-peak times averaged 3.6% greater than mean transit time (4.39 +/- 1.76 seconds vs. 4.24 +/- 1.82 seconds, P less than .05), though they correlated well with green dye values (r = .97; y = .97 x +.44). It was concluded that peak-to-peak transit times are excellent approximates of standard dye-dilution mean transit times and may simplify calculations of the pulmonary circulation when videodensitometric or radionuclide techniques are utilized.

Validation of cardiac output estimates by digital video subtraction angiography in dogs. Correlation with thermodilution values.

To determine the validity of cardiac output estimates obtained by digital video subtraction angiography (DVSA), they were compared with thermodilution values in 6 anesthetized dogs. Multiple levels of cardiac output were produced in each dog by graded openings of peripheral arteriovenous fistulas. Both direct contrast and mask-mode images were evaluated. There was good correlation between thermodilution and direct contrast values (r = 0.88) as well as between thermodilution and mask-mode values (r = 0.89), though the mask-mode outputs were 12 +/- 1.1% less than the direct contrast values (p less than 0.05). Direct contrast and mask-mode values correlated well (n = 6; r greater than or equal to 0.95). Digital outputs exhibited little variation, indicating excellent reproducibility. These results demonstrate the validity of area-length estimates of cardiac output by DVSA.

Experience with metrizamide in patients with previous severe anaphylactoid reactions to ionic contrast agents.

Metrizamide was employed in six patients who, during angiography, had had severe anaphylactoid reactions to conventional ionic contrast media. Five of these patients had received corticoid premedication before injection of both conventional contrast medium and metrizamide; anaphylaxis occurred only after administration of conventional contrast media. Four patients had no detectable reaction whatsoever after metrizamide; a fifth had only transient tachycardia. In the sixth patient, delayed edema developed in the region of his cerebral arteriovenous malformation. These observations suggest a marked decrease in the incidence and severity of anaphylactoid reactions when metrizamide is substituted in patients who have reacted to ionic contrast media. Metrizamide, or a comparable nonionic contrast agent, should be strongly considered in patients who have had a severe reaction to conventional contrast medium.

The role of pararenal collaterals in assessing renal artery stenosis before and after percutaneous transluminal angioplasty.

For the past several years, observation of flow direction in non-parenchymal renal artery branches, particularly during pharmacoangiography, has proved to be extremely reliable in the preoperative evaluation of the hemodynamic significance of renal artery stenoses. The advent of percutaneous transluminal angioplasty (PTA) has expanded the applications for these methods. Their value in PTA is demonstrated through five illustrative cases. In four stenoses shown to be significant before PTA, clinical responses were favorable. In one case undergoing PTA of an anatomically severe, but hemodynamically insignificant stenosis, blood pressure was unchanged after PTA. After PTA, observation of orthograde flow in the pararenal arteries confirms the adequacy of the procedure, and predicates a favorable clinical response.