Biomedical subjects

G D Davis

Publications and source records attributed to G D Davis.

At least 55 records · Page 3Linked to original sources

PubMed1975

Regional left ventricular wall dynamics before and after sublingual administration of nitroglycerin.

Regional wall dynamics of the left ventricle before and after sublingual administration of 0.6 mg of nitroglycerin were determined from left ventricular angiograms in 27 patients undergoing coronary arteriography. Regional wall dynamics were quantitatively measured from 60/sec determinations of wall thickness and derived peak rate of systolic wall thickening (peak dTw/dt) in selected sites of the left ventricle. A total of 70 regions were studied. Analysis of the same segment before and after administration of nitroglycerin revealed that the mean change in peak dTw/dt was +1.97 cm/sec in segments with an initial peak dTw/dt of less than 5 cm/sec, in contrast to a change of +0.66 cm/sec in segments with an initial control value of 5 cm/sec or greater. Akinetic or dyskinetic areas did not show improvements after nitroglycerin. In 11 left ventriculograms, an area that was initially hypokinetic manifested an increase in rate of wall thickening after nitroglycerin. The mean increase in peak dTw/dt in anterior segments with electrocardiographic evidence of myocardial infarction was 0.18 cm/sec (P less than 0.05) after nitroglycerin, compared with a mean change of 1.33 cm/sec in anterior segments without such evidence. This study presents evidence for a regional myocardial response to nitroglycerin with differing responses within the same ventricle apparently depending upon the functional state of the underlying myocardium.

Aged↗

PubMed1975

Relation of intraoperative or early postoperative transmural myocardial infarction to patency of aortocoronary bypass grafts and to diseased ungrafted coronary arteries.

Serial preoperative and postoperative electrocardiograms and vectorcardiograms were obtained in 500 patients undergoing saphenous vein aortocoronary artery bypass graft surgery. Evidence of transmural myocardial infarction was found early postoperatively in 67 patients (13 percent). Age and sex distributions, number of vessels diseased or vessels grafted, and preoperative and postoperative New York Heart Association functional classification (mean follow-up, 26 months) did not differ in the groups with and without infarction. Increased duration of cardiopulmonary bypass time (more than 120 minutes) was slightly greater in the group with infarction (P smaller than 0.05). Multivariate analysis revealed that 60 percent of patients in the group with infarction were identified by a 1st day serum glutamic oxaloacetic transaminase value greater than 100 U/liter; however, for each such patient identified, there was approximately one false positive result. Use of other values (creatine phosphokinase, cardiopulmonary bypass time and total anoxic rest time) did not improve discrimination. Twenty-five percent of all transmural infarctions occurred within the zone of myocardium supplied by a diseased ungrafted artery. In 32 patients with early evidence of transmural mycardial infarction in a zone of myocardium supplied by a grafted artery, postoperative angiography showed as many with patent as with occluded grafts. Of 154 patients in the group without infarction who had early postoperative graft angiograms, 30 (19 percent) had one graft occluded and yet no evidence of transmural infarction by our criteria. Therefore, early postoperative evidence of transmural myocardial infarction as defined in this study is an unreliable indicator of the status of the graft supplying the zone of infarction.

Adult↗

PubMed1975

Surgical management of large bronchial collateral arteries with pulmonary stenosis or atresia.

Single or multiple large bronchial collateral arteries may provide all or some of the pulmonary arterial blood flow in patients with proximal atresia of the pulmonary artery, and even in patients with only pulmonary stenosis. At the time of corrective surgery such arteries must be ligated in order to provide favorable operating conditions, to avoid cardiac overdistention during repair, and to prevent left-to-right intrapulmonary shunting postoperatively. Their ligation and control require precise preoperative definition of their number, origin, and course, and special intraoperative methods for their exposure. Associated hypoplasia of the pulmonary arteries may be severe enough to preclude corrective operation, but these hypoplastic arteries may enlarge in response to increase of blood flow through them resulting from a surgically created shunt. Experience with 14 surgically managed cases of this type forms the basis for the report.

Adolescent↗

PubMed1975

Double-outlet right ventricle associated with persistent common atriventricular canal.

A variant of double-outlet right ventricle (DORV) associated with common atrioventricular (A-V) canal was identified. As yet, this syndrome has not been successfully repaired. Of 16 patients with this diagnosis, 14 had the diagnosis confirmed at postmortem examination and two had the diagnosis confirmed by exploratory cardiotomy. The 16 patients were divided into two groups according to the position of the cardiac apex: group 1, ten patients with levocardia, and group 2, six patients with dextrocardia and ventricular inverson. When pulmonary stenosis was present, the clinical presentation was similar to that in tetralogy of Fallot, and when such stenosis was not, the presentation was similar to that in ventricular septal defect with bidirectional shunting. The electrocardiogram had the typical feature of common A-V canal. The right ventricular angiocardiogram had features typical of DORV. The left ventricular angiocardiogram revealed left ventricular outflow deformity typical of A-V canal in patients with levocardia but not in those with dextrocardia. Splenic anomalies were commonly seen (nine of the 16 patients). Asplenia was present in seven, and polysplenia in two. Ten patients had persistent left superior vena cava, seven had common atricum, six had anomalous pulmonary venous connection, and three had subaortic stenosis. Twelve of the 16 patients had pulmonary stenosis. Of the 16, 14 had common A-V canal (Rastelli type C) and two had a ventricular septal defect of the persistent common A-V type.

Adolescent↗

PubMed1975

Aorta-coronary artery saphenous vein bypass surgery: clinical and angiographic results.

In a series of 500 consecutive patients undergoing aorta-coronary artery saphenous vein bypass surgery, operative mortality was 2.5% (1% with one-vessel disease, 2% with two-vessel disease, and 3% with three-vessel disease). Transmural myocardial infarction occurred within 30 days after operation in 67 cases (13%) and caused 10 of the 16 deaths in that period. Among 484 patients followed 1 to 58 months (median, 26 months), there have been 20 deaths. Of the 464 survivors, 65% had complete relief of angina, 24% were improved, and 11% were unimproved. In 162 patients who underwent postoperative graft angiography between 1 and 42 months after surgery, a strong positive relationship existed between clinical response and completeness of myocardial revascularization as defined by the presence of a patent graft to all major coronary arteries with greater than 50% stenosis. A similar relationship was found between postoperative multistage treadmill exercise response and completeness of myocardial revascularization. Thus, 82% of patients completely revascularized were asymptomatic at the time of postoperative graft visualization, and 91% had a negative treadmill exercise response.

Adult↗

PubMed1975