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Biomedical subjects

J D Garnic

Publications and source records attributed to J D Garnic.

26 records · Page 2Linked to original sources
PubMed1981

Frequency and clinical significance of failure to visualize the conus artery during coronary arteriography.

In patients with occlusion of the left anterior descending coronary artery (LAD) or right coronary artery (RCA), the conus artery, which arises at or near the origin of the RCA, often serves as a principal source of collateral circulation. Coronary arteriograms in 508 adult patients revealed that in 80.5% the conus artery was well visualized on the RCA angiogram, but that in 19.5% it was not adequately visualized due to injection of contrast distal to its origin. In the latter patients, the presence of conus-LAD or conus-RCA collaterals might therefore go undetected. Because the degree of distal filling via collateral circulation affects medical and surgical decisions, it is important to attempt to visualize the conus artery adequately whenever the LAD or RCA is obstructed.

Angiography↗
PubMed1981

Therapeutic embolization of the gastroduodenal artery in hepatic artery infusion chemotherapy.

Transcatheter embolization of the gastroduodenal artery with Gelfoam was performed in 12 patients undergoing percutaneous hepatic artery catheterization for infusion chemotherapy of metastatic liver disease. The purpose of the embolization was to prevent chemotherapeutic drugs from reaching the stomach and duodenum and thereby inducing gastrointestinal toxicity in patients in whom the catheter tip could not be satisfactorily positioned beyond the gastroduodenal origin. Embolization proved safe and effective in eight cases. Three other patients experienced clinical problems that may or may not have been related to embolization. The final patient had a significant complication (necrosis of the pancreatic head and gastric mucosa) that was felt to be directly related to the embolization. Transcatheter gastroduodenal occlusion may help reduce gastrointestinal toxicity of intraarterial infusion chemotherapy. However, it may on occasion be associated with significant complications, particularly in patients who are debilitated due to metastatic disease.

Adult↗
PubMedDate not supplied

Anatomic variations of the coronary arteries supplying the anterolateral aspect of the left ventricle: possible explanation for the "Unexplained" anterior aneurysm.

Coronary arteriograms of 418 adult patients were studied to ascertain the frequency of variations in blood supply of the anterolateral free wall of the left ventricle; 92.6% had from one to three ramus medianus or diagonal branches supplying this area. Complete absence of any ramus medianus or diagonal branches was exceedingly rare (only 0.5% in this series), and when this occurs the angiographer should suspect complete occlusion of one or more such branches immediately at their origins. Failure to detect ostial occlusion of a ramus medianus or diagonal branch may be a cause of significant misinterpretation of coronary arteriograms.

Adult↗
PubMedDate not supplied

Timing and magnitude of the postural effect on the distribution of pulmonary blood flow.

The magnitude and timing of the effects of postural change on pulmonary blood flow distribution were studied in dogs by means of computed tomography (CT) and radioactive microspheres. A change in the mean attenuation values was demonstrated by CT in the anterior and posterior lung zones after change from the supine to the prone position. Similarly, a significant shift in blood flow distribution, as measured by microspheres, occurred rapidly, within 1 minute of the time of change from upright to supine position. These data confirm the importance of gravity in determining blood flow distribution in the lungs and demonstrate that maximum readjustments occur within 1 minute after postural change.

Animals↗
PubMedDate not supplied

Differential large and small vessel responses to serotonin in the dog hindlimb in vivo: role of the 5HT2 receptor.

Serotonin (5HT) constricts large arteries in vitro, an effect which seems contrary to 5HT-induced increases in blood flow observed in vivo. We used angiography to assess large artery responses, and blood flow (Q, electromagnetic flowmeter) to assess arteriolar responses to 5HT, norepinephrine (NE), and antagonists in the femoral circulation of the intact, anesthetized dog. 5HT constricted large arteries at a threshold dose of less than 10 micrograms/min, giving a 45 +/- 3% reduction of popliteal artery diameter at 100 micrograms/min (p less than 0.001). NE failed to constrict large arteries. With 100 micrograms/min 5HT, Q increased (delta Q = 108 +/- 26 ml/min; p = 0.001). NE decreased Q. Ketanserin, a 5HT and alpha 1-adrenergic antagonist, exerted a dose-dependent inhibition of 5HT-induced large artery constriction. Methysergide partially blocked the 5HT-induced large artery constriction. Ketanserin potentiated the Q response to 5HT whereas higher doses of methysergide reduced the Q response to 5HT. Neither indomethacin nor propranolol altered either response. Failure of NE to constrict large arteries in vivo and ketanserin antagonism of constriction produced by 5HT suggest the response to 5HT involves the 5HT2 receptor. No role for the 5HT2 receptor in blood flow responses is suggested. These observations may have implications for therapy of occlusive vascular disease.

Animals↗
PubMedDate not supplied

Prospectively gated cardiac computed tomography.

A fourth-generation scanner has been modified to perform prospectively gated cardiac computed tomography (CT). A computer program monitors the electrocardiogram (ECG) and predicts when to initiate the next scan in a gated series in order to acquire all projection data for a desired phase of the heart cycle. The system has been tested with dogs and has produced cross-sectional images of all phases of the cardiac cycle. Eight to ten scans per series were sufficient to obtain reproducible images of each transverse section in the end-diastolic and end-systolic phases. The radiation dose to the skin was approximately 1.4 cGy per scan. The prospectively gated system is more than twice as efficient as a retrospectively gated system in obtaining complete angular projection data for a 10% heart cycle window. A temporal smoothing technique to suppress reconstruction artifacts due to sorting inconsistent projection data was developed and evaluated. Image noise was reduced by averaging together any overlapping projection data. Prospectively gated cardiac CT has also been used to demonstrate that the error in attenuation measured with a single nongated CT scan through the heart can be as large as 50-60 CT numbers outside the heart in the lung field.

Animals↗
PubMedDate not supplied

Prospectively gated cardiac CT. Preliminary results in normal and postinfarction animal models.

Cardiac motion introduces significant artifacts into standard CT images obtained through the heart. A newly developed prospectively gated CT system produced 87 gated scan sets in ten normal and infarcted dogs. Each cycle can provide up to 24 37-70 msec composite images of one transverse slice, equally spaced in time through the cardiac cycle. Eight to 12 2-second scans, obtained during a constant infusion of contrast, were required to collect the data for each gated set. The left and right ventricular myocardium was clearly seen, regions of myocardial infarction were identified, and atrial and ventricular filling and emptying were visualized. In areas of infarction, wall thickness was unchanged from diastole to systole. In addition to improved resolution, a gated CT series evaluation of wall motion abnormalities may provide a better means of locating myocardial infarction than the ungated CT image.

Animals↗