Search PubMed⌕ Search

Biomedical subjects

W G Daniel

Publications and source records attributed to W G Daniel.

190 records · Page 11Linked to original sources
PubMed1978

The application of thermography in the study of coronary blood flow.

The technique presented in this paper is based on the authors' previous observations in which they found that artificial decrease of blood flow to a portion of the heart muscle leads to an immediate and proportional drop in the regional myocardial temperature. It appeared to the authors as a logical next step to apply the thermographic camera to a monitor and to record such changes in the human patient during coronary surgery and to use the data to draw conclusions applicable to regional blood supply and to blood flow through surgically inserted vein grafts. They found that, on the normothermic heart, there were well-identifiable "cold" patches corresponding with areas of impaired coronary circulation. By infusion of blood to the ischemic myocardium through individual release of the bypass grafts, the thermogram responded by immediate appearance of "warm" spots corresponding with the areas supplied by the grafts. Even more dramatic demonstration of graft patency and outline of the area supplied by the graft could be performed by injecting cold saline solution into the grafted saphenous veins. In the author's experience this most interesting new method proved to be a useful tool in coronary surgery both as an adjunct in delineating ischemic areas and in proving the patency and efficiency of the grafts inserted.

Blood Flow Velocity↗
PubMedDate not supplied

Value of transesophageal color Doppler echocardiography for detection of different types of atrial septal defect in adults.

In 121 adults, the value of transthoracic and transesophageal color Doppler echocardiography for detection of different types of atrial septal defect (ASD) or of partial anomalous pulmonary venous return was analyzed. The 121 patients had a total of 129 defects with left-to-right atrial shunting (including eight patients with two types of defects). All of six cases with primum-type ASD were diagnosed correctly by both echocardiographic methods. Ninety-seven patients showed a secundum-type ASD during transesophageal echocardiography: by transthoracic echocardiography, only eight (20%) of the 40 small defects (diameter < 5 mm) were detected as compared with 15 (83%) of the 18 defects with a diameter of 5 to 10 mm and all 39 defects with a diameter > 10 mm. A sinus venosus--type ASD was evident by transesophageal echocardiography in 11 patients, of which only one (9%) was demonstrated by the transthoracic approach. Partial anomalous pulmonary venous return was seen by transesophageal echocardiography in 13 patients but missed in two other patients in whom anomalous pulmonary venous return was subsequently identified by surgery (both with anomalous return of the upper right pulmonary vein into the superior vena cava). By use of the transthoracic technique, partial anomalous venous return was detected in only two cases, both of which had "scimitar syndrome." Compared with transthoracic echocardiography, the transesophageal approach is clearly superior in the detection of small secundum-type ASD, sinus venosus--type ASD, and partial anomalous pulmonary venous return.

Adolescent↗
PubMedDate not supplied

Echocardiographic and hemodynamic characteristics of atrial septal defects created by percutaneous valvuloplasty.

Twenty-nine patients were studied by pulsed, continuous wave, and color Doppler before and after percutaneous transseptal valvuloplasty. New atrial septal defects were detected in 14 patients, and the patients were monitored for up to 320 days after the procedure. The diameter of the defect, best evaluated by the transesophageal approach, was 3 to 15 mm. A narrow, high velocity (1.4 to 3.1 meters per second) left-to-right shunt jet was detected in 13 of 14 patients. The shunt jet was continuous in nine of 14 patients, late systolic-holodiastolic in four patients, and bidirectional in one patient. Cardiac catheterization in nine patients confirmed the Doppler findings and demonstrated a peak pressure gradient of 10 to 32 mm Hg between the left and right atria. Oximetry revealed a calculated pulmonary to systemic flow ratio ranging from 2.3:1 in the patient with the largest atrial septal defect by echocardiography to 1:1 (no oxygen saturation step-up) in the patient with the smallest atrial septal defect. In the three patients who underwent cardiac surgery, the operative findings confirmed those of echocardiography. We concluded that atrial septal defects are common after transseptal valvuloplasty. Usually, their relatively small size and the underlying valvular disease that produces high left atrial pressure are responsible for the high pressure gradient between the left and right atria. This results in the high velocity and continuous shunt jet detected by Doppler echocardiography.

Adult↗
PubMedDate not supplied

Echocardiographic evaluation of the five-chamber heart: a rare congenital coronary anomaly.

Coronary artery fistulas are rare congenital anomalies that usually drain into one of the cardiac chambers or veins. The current patient was found to have a distinctly unusual anatomic picture, with a fifth cardiac chamber appearing at the cardiac apex. This proved to be the drainage site for a large coronary artery fistula originating in the left anterior descending coronary artery. The anatomic relations and blood flow patterns were demonstrated with transthoracic and transesophageal echocardiography.

Adult↗
PubMedDate not supplied

Risk of bacteremia induced by transesophageal echocardiography: analysis of 100 consecutive procedures.

The incidence of bacteremia induced by transesophageal echocardiography (TEE) and, consequently, the need for an antibiotic prophylaxis before TEE is still controversial. Therefore, we studied the incidence of bacteremia associated with TEE prospectively in 100 consecutive patients without clinical or laboratory signs of bacterial infection. Blood samples were drawn immediately before and at 0, 5, and 15 minutes after TEE. In addition, swabs were taken from the pharyngeal region before TEE and from the distal part of the TEE-probe before and after TEE. All blood cultures taken before TEE remained sterile. After TEE, three positive blood cultures were found in two patients: the first patient had two different species of coagulase-negative staphylococci in cultures taken at 0 minutes (Staphylococcus capitis) and 15 minutes (Staphylococcus cohnii) after TEE, whereas the sample taken after 5 minutes remained sterile. In the second patient, Propionibacterium species appeared after 7 days of processing in a culture taken immediately after TEE, but not in the samples taken after 5 and 15 minutes. None of the three microorganisms found in the blood were simultaneously isolated in pharyngeal specimens or TEE-probe specimens of the same patient. Thus positive blood cultures in both patients were considered contaminated. This study demonstrates that TEE, when performed by an experienced investigator, is not associated with an increased risk of bacteremia. Accordingly, it is justified to perform TEE examinations (also in high-risk patients) without antibiotic prophylaxis.

Adult↗
PubMedDate not supplied

A patient with right and left atrial membranes: the role of transesophageal echocardiography and magnetic resonance imaging in diagnosis.

A patient who had right and left atrial membranes was examined. The diagnosis and the hemodynamic significance of both membranes were detailed by transesophageal echocardiography and were confirmed by magnetic resonance imaging. Transesophageal imaging was found to be superior to routine echocardiography in visualization of these atrial structures.

Adult↗
PubMedDate not supplied

Overlapping cross-sections significantly improve the reproducibility of coronary calcium measurements by electron beam tomography: a phantom study.

PURPOSE: We conducted phantom studies to investigate whether overlapping cross-sections and volumetric scoring would significantly improve interscan reproducibility of electron beam tomography (EBT) for coronary artery calcium quantification. METHOD: Fifteen phantoms simulating various amounts of coronary calcification were scanned in five different positions with a slice thickness of 3.0 mm and a table feed of 3.0, 2.5, and 2.0 mm. For the conventional "Agatston score" and a "volume score" (total volume of calcified lesions), interscan variabilities were compared between the three image acquisition protocols. RESULTS: Agatston score variability was significantly lower for the 2.0 mm table feed than for the 3.0 or 2.5 mm table feed (3.0 mm: 22.9 +/- 10.3%; 2.5 mm: 13.6 +/- 8.2%; 2.0 mm: 8.9 +/- 5.5%). Volume score variability was significantly lower for 2.5 and 2.0 mm table feed than for 3.0 mm table feed (3.0 mm: 21.7 +/- 11.0%; 2.5 mm: 10.9 +/- 5.9%; 2.0 mm: 9.8 +/- 5.9%). CONCLUSION: Overlapping cross-sections, especially in combination with volumetric scoring, significantly improved interscan reproducibility of EBT calcium quantification in a phantom study.

Aged↗