ABSTRACT
Guidelines that are frequently used to select patients with suspected pulmonary embolus for pulmonary angiography evolved from studies conducted 10 to 15 years ago. To determine if clinical practice in a referral medical center should continue to be based on these guidelines, clinical and angiographic data on 106 patients recently studied were compared with similar data obtained from the same institution in the previous era. The need to perform angiography if a lung scan demonstrated low or high probability for embolus was also examined, along with clinical, laboratory, and hemodynamic findings previously reported to be of diagnostic utility. There has been a marked change in the spectrum of patients studied. Cancer patients and patients who have undergone abdominal and pelvic surgery comprise the preponderance of patients undergoing angiography. Lung scans had a clinically important error rate in that more than one third of these selected patients with either a high- or low-probability scan had discordant results on angiography. Clinical criteria for selecting patients for pulmonary angiography should reflect the contemporary spectrum of patients with pulmonary embolus, as well as the limitations of clinical judgment and of the lung scan.
Subject(s)
Angiography , Lung/diagnostic imaging , Pulmonary Embolism/diagnostic imaging , Angiography/statistics & numerical data , Cardiac Catheterization , Cardiovascular Diseases/complications , Evaluation Studies as Topic , Hemodynamics , Humans , Lung/blood supply , Neoplasms , Postoperative Complications , Pulmonary Circulation , Pulmonary Embolism/diagnosis , Pulmonary Embolism/physiopathology , Radionuclide Imaging , Risk , Ventilation-Perfusion RatioABSTRACT
The increasing role of percutaneous transluminal angioplasty in the therapy of renal artery stenosis has, in turn, emphasized the need to optimize imaging of the entire length of the main renal artery and its major branches. The usual angiographic positioning techniques for anteroposterior and oblique views may not be adequate to define the precise location and extent of a stenosis. The authors combine oblique projections with sagittal angulation of the x-ray tube to augment the standard imaging methods for selective renal arteriography.
Subject(s)
Angiography/methods , Renal Artery Obstruction/diagnostic imaging , Humans , Posture , Renal Artery/diagnostic imagingABSTRACT
Coronary artery bypass graft (CABG) surgery is in widespread use. Bypass graft angiography continues to be an integral part of the evaluation of the post-CABG patient. Future methods may include computed tomography and digital subtraction angiography to assist in this evaluation.
Subject(s)
Coronary Angiography , Coronary Artery Bypass , Graft Survival , Coronary Vessels/pathology , HumansABSTRACT
The effects of acid-base imbalance on ventricular pacing thresholds were studied in anesthetized dogs with complete heart block with the use of an oscilloscope and current probe. Acidosis (base excess-15) and alkalosis (base excess + 15)both resulted in significant increases in threshold voltage and current requirements at all stimulus durations tested. Chronaxie, however, was not significantly affected by shifts in acid-base balance. Abnormalities of acid-base status may adversely affect the accuracy of threshold values obtained during evaluation of different electrode designs and during electrodes implantation for clinical cardiac pacing.
Subject(s)
Acidosis/physiopathology , Alkalosis/physiopathology , Heart Block/therapy , Heart Conduction System/physiopathology , Pacemaker, Artificial , Animals , Bicarbonates , Dogs , Heart Block/physiopathology , Hydrochloric AcidABSTRACT
To determine the effect of stimulation site on cardiac pacing thresholds, identical, small-surface area, cathodal, Elgiloy electrodes were placed intramyocardially on the left and right ventricular apices and transvenously into the right ventricular apex of 20 dogs in complete heart block. At seven stimulus durations, threshold voltage and current were measured directly with an oscilloscope and current probe. Left ventricular intramyocardial pacing required less threshold stimulus energy than right ventricular intramyocardial or right ventricular endocardial pacing. Previous studies that determined lower thresholds with transvenous right ventricular endocardial leads than with directly placed myocardial leads used stimulating electrodes of differing configuration, surface area, and materials at the different sites and/or used epicardial rather than intramyocardial electrodes. These factors biased the results in favor of the endocardial site. When all clinical and electrophysiological facotrs are considered, direct intramyocardial placement of electrodes deserves a much wider acceptance and application than it now enjoys.