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Biomedical subjects

H B Barner

Publications and source records attributed to H B Barner.

At least 163 records · Page 9Linked to original sources
PubMed1977

Pulmonary and left atrial hemodynamics in mital stenosis.

A laboratory model has been utilized to evaluate left atrial and pulmoanry hemodynamics while comparing atria of three different compliances, five valve orifices, four pulmonary complicances, two venous pressures, and a predetermined pulmonary vascular resistance. The data demonstrate significant relationships between these variables and cardiac output, pulmonary artery pressure, and left atrial pressure and between the variables themselves. The complexity of these interrelationships is consistent with the lack of simple linear relations between current clinical measurements and emphasizes the need for measurements of compliance if the hemodynamic consequences of mitral stenosis are to be better understood.

Blood Pressure↗
PubMed1977

Topical cardiac hypothermia and phrenic nerve injury.

The relationship between ice-chip cardioplegia and impaired left diaphragmatic function was evaluated in dogs. Direct or indirect contact of the phrenic nerve with crushed ice for 30 or 60 minutes resulted in phrenic paralysis for 6 to 28 days, with responsiveness returning from 7 to 62 days later. Microscopical examination of injured nerves revealed injury to the myelin sheath and preservation of axons. Paralysis of the left diaphragm after topical cardiac hypothermia may be secondary to cold injury of the phrenic nerve, which is reversible.

Animals↗
PubMed1977

Coronary venous arterialization: acute hemodynamic, metabolic, and chronic anatomical observations.

Nine dogs that had anastomosis of the internal mammary artery (IMA) to the left anterior descending coronary vein (LADV) were studied acutely on right-heart bypass. Occlusion of the left anterior descending coronary artery (LADA) and LADV without venous arterialization resulted in a significant decline in stroke work, total coronary flow, and myocardial oxygen uptake; with reactive hyperemia an increase in lactate and pyruvate consumption resulted. Occlusion of the LADA and LADV with VA did not change these variables greatly, except for a marked increase in total coronary flow with reactive hyperemia. Chronic venous arterialization in 14 dogs was associated with a 14% mortality, while 10 controls had a 40% mortality. Dogs were killed at six weeks, and prior angiography in 9 showed patency of the IMA to the heart without filling of cardiac veins. All dogs had infarcts in the distribution of the LADA; these infarcts were smaller in dogs with venous arterialization. The anastomoses were obliterated by mature or maturing fibrous tissue, with alteration of the vein so that it was frequently not discernible, while the IMA was well preserved. Distal veins had foci of intimal proliferation, subintimal fibrosis, and medial hypertrophy. Although venous arterialzaiton provides protection for the acutely ischemic myocardium, this effect does not persist, perhaps because of anastomotic occlusion due to fibrous proliferation.

Animals↗
PubMed1977

Aortic venting. Comparison of vent effectiveness.

Three commercially available aortic vents have been evaluated as to effectiveness in removing small volumes of air introduced into a mock circulatory circuit. Without aspiration, Vent 2 was the most effective and removed 58 per cent of 0.1 ml., 90 per cent of 0.5 ml., and 74 per cent of 1.0 ml. boluses at a cardiac output of 2 L. At a cardiac output of 4 L., Vent 2 removed 42, 76, and 49 per cent, respectively. With aspiration (Vent 2 not designed for aspiration) and a 2 L. cardiac output, Vents 1 and 3 removed 84 to 98 per cent of 0.1 ml., 68 to 92 per cent of 0.5 ml., and 74 to 86 per cent of 1.0 ml. boluses. With aspiration and a 4 L. cardiac output, Vent 3 was significantly more effective than Vent 1 and removed 92 to 94 per cent of 0.1 ml., 82 to 86 per cent of 0.5 ml., and 77 to 80 per cent of 1.0 ml. boluses. One liter of canine blood was aspirated through Vents 1 and 3 and a flow rate of 250 ml. per minute. For Vent 1, serum hemoglobin levels increased from 40 to 249 mg. per 100 ml. and for Vent 3 from 49 to 212 mg. per 100 ml. There are significant differences in the ability of commercially available aortic vents to remove small air bubbles trapped in the heart after initial direct cardiac venting. Vents having the capability of aspiration are more effective and result in acceptable hemolysis.

Aorta↗
PubMed1977

Topical cardiac hypothermia for myocardial preservation.

We compared moderate (29 degrees C.) and profound (5 degrees C.) (ice chips) cardiac hypothermia for myocardial preservation during aortic cross-clamping for 30 or 60 minutes in a canine right heart bypass preparation. Ventricular function deteriorated significantly at 29 degrees C. but not at 5 degrees C. Maximum dp/dt declined only after 60 minutes of ischemia at 29 degrees C., and Vmax decreased after one hour at either temperature. Lactate and pyruvate washout were greater after 29 degrees C., and pyruvate production persisted after 60 minutes of ischemia at 29 degrees C. Reactive hyperemia was greater after 30 minutes of ischemia at 29 degrees C. Reactive hyperemia was greater after 30 minutes of ischemia at 29 degrees C., and total coronary flow remained elevated after 60 minutes of ischemia at 29 degrees C. Coronary flow distribution was not altered by hypothermia. Ultrastructural changes were primarily time dependent and not temperature dependent. Ice-induced subepicardial injury was not evident in the ultrastructure or by flow distribution. Sixty minutes of profound topical cardiac hypothermia is moderately well tolerated by the canine heart, but functional and structural alterations are evident.

Animals↗
PubMed1977

Myocardial injury following myocardial revascularization. Detection by isoenzyme analysis.

To clarify the value of isoenzymes in the detection of acute myocardial injury (AMI) associated with coronary artery bypass grafting, 350 consecutive patients (804 grafts) were evaluated with serial electrocardiograms (ECG) and serum levels of serum glutamic oxaloacetic transaminase (SGOT), total creatinine phosphokinase (CPK), and lactic dehydrogenase (LDH) on Days 0, 1,2,3,4,5, and 7. Graft patency 1 to 6 months postoperatively was 92%. Sixty patients (18%) had ECG evidence of AMI. Four patients died (1.1%) Of the 185 patients with serial LDH isoenzyme analysis, 46 had elevated cardiac fraction (LDH-1). Only 35 of these had AMI by ECG. The others had nonspecific ECG changes, but associated enzymatic andhemodynamic evidence of AMI. The CPK-MB band was elevated in all patients in the immediate postoperative period, but did not correlate with ECG, hemodynamic, or enzymatic evidence of AMI. The diagnosis of AMI following coronary artery bypass could not be substantiated by evaluation of total LDH, CPK, or CPK-MB. LDH-1 is specific in detecting AMI after a coronary artery bypass graft.

Adult↗
PubMed1976

Evaluation of choledochoduodenostomy in the treatment of malignant obstruction of the biliary tree.

The results of direct decompression of the common duct for malignant obstruction of the distal biliary tree by side-to-side choledochoduodenostomy are presented. Thirty-three patients were treated with twenty-four (73 per cent) having carcinoma of the pancreas. Seventy-two per cent of the patients had had previous cholecystectomy or cholelithiasis whereas the common duct was utilized in preference to cholecystojejunostomy in six patients. The operative mortality was 12 per cent and six patients had complications. No deaths could be attributed to the choledochoduodenostomy, and complications did not significantly affect palliation. Mean postoperative survival was 10 +/- 0.9 months. Two patients had obstruction of the anastomosis as a terminal event. This study suggests that appropriately applied choledochoduodenostomy is a simple, effective means to decompress the common duct obstructed by tumor.

Aged↗
PubMed1976

Intraaortic balloon assistance.

Intraaortic balloon (IAB) assistance in 64 patients over 2 1/2 years has resulted in a survival rate of 11% (1 patient) when used alone but 47% when utilized in patients treated surgically (long-term survival, 38% [21 patients]). Patients undergoing coronary artery bypass grafting or aortic valve replacement have a long-term survival of 50% (8 and 9 patients, respectively). The required duration of IAB support has a bearing on the clinical result. Complications have been minimal. Though it was originally developed to assist in the nonoperative management of complications of ischemic heart disease, IAB assistance offers significant promise as an adjuvant to operative therapy for both ischemic and valvular heart disease.

Aortic Valve↗
PubMed1976

In favor of the Y-graft for aortocoronary bypass.

The technique of multiple coronary artery bypass grafting has included separate conduits, snake grafts, and Y-grafts. Against the Y-graft have been reports of lesser patency and several theoretical objections. The theory is discussed and a laboratory model presented which demonstrates a flow difference of 2 ml/5 sec or less between Y-grafts and single grafts. In conjunction with this, 171 patients having aortocoronary bypass were analyzed and showed a combined one-year graft patency of 77% with no significant difference between single grafts and Y-grafts. It is concluded that the technical simplicity of Y-grafts is advantageous and that, if the operation is performed within the guidelines set forth, revascularization with Y-grafts is an acceptable method.

Animals↗
PubMed1976

Aortic aneurysm in childhood: report of six instances.

Six instances of aortic aneurysm in children have been observed in the past 15 years. Four children with aortic stenosis and coarctation of the aorta had aneurysmal dilatation of the ascending aorta, and two children with coarctation of the aorta had ruptured post-stenotic dilatation of the descending aorta. Our observations suggest that aortic aneurysm can be the result of hemodynamic stress, although developmental anomaly of the aorta associated with aortic stenosis or coarctation could be responsible for the development of the aneurysm.

Adolescent↗
PubMed1976

Operative flow measurements and coronary bypass graft patency.

Early (one week) and late (one year) postoperative angiography was performed in 142 patients having 310 grafts (117 right coronary artery [RCA], 134 left anterior descending [LAD], and 59 circumflex coronary artery [CCA]) to assess the factors responsible for failure of aorta-coronary artery saphenous vein grafts. Early catheterization revealed an 85.5 per cent patency rate with similar rates for each artery (RCA 88 per cent, LAD 85 per cent, and CCA 81 per cent). At one year 238 grafts remained patent, for a cumulative patency rate of 76.8 per cent with a similar distribution for each vessel (RCA 75 per cent, LAD 78 per cent, and CCA 76 per cent). Intraoperative flow measurements were correlated with early and late patency. Grafts with a basal flow less than 20 ml. per minute have a 42 per cent early closure rate and a 21 per cent late closure rate (cumulative 63 per cent). A basal flow of less than 40 ml. per minute was associated with a 25 per cent early failure and an 11 per cent late failure rate (cumulative 36 per cent). Basal flow at levels greater than 40 ml. per minute was not associated with an increased probability of graft closure. Absence of reactive hyperemia (30 second graft occlusion) was associated with a 19 per cent probability of early closure and a 31 per cent probability of cumulative thrombosis. A papaverine-induced flow increase (15 mg. given into the graft) of less than 100 per cent over basal flow gave a 20 per cent probability of early failure and 30 per cent probability of cumulative closure. Thus intraoperative basal flow measurements are of predictive value in determining the fate of aorta-coronary artery vein bypass grafts, and vasodilatory maneuvers provide little additional information.

Coronary Artery Bypass↗
PubMed1976

Patency of internal mammary-coronary grafts.

Patency of internal mammary artery (IMA) coronary grafts was evaluated in 150 patients having an early (20 days) and late (13 months) postoperative angiogram. Early and late failure for 76 right IMA grafts was 3 and 5 respectively and for 139 left IMA grafts 7 and 7 an overall IMA patency of 95% and 90%. The IMA and coronary internal diameter did not relate to graft closure. Right IMA free flow did not correlate with graft closure. Free flow for thrombosed left IMA grafts (91 ml/min) was significantly (P less than 0.05) lower than for patent grafts (118 ml/min). Right IMA anastomotic flow of 55 ml/min was significantly (P less than 0.001) higher than occluded graft flow of 26 ml/min as was true for patent left IMA grafts (55 ml/min) and occluded grafts (43 ml/min) (P less than 0.025). Five of 215 IMA grafts had diffuse stenosis (greater than 50%). Saphenous vein coronary bypass was performed in 88 instances with an early patency of 89% (79/88) and a late patency of 88% (78/88). Only one of 38 vein grafts to the right coronary artery failed whereas eight of 44 grafts to the circumflex artery occluded. Experience was associated with increased late IMA patency from 81% (57/70), to 89% (;8/76), to 99% (68/69) in each successive group of 50 patients. Currently, the left IMA is routinely used for the left anterior descending artery and the right IMA is rarely used.

Adult↗
PubMed1976

Use of automated, on-line pyruvate analysis.

Normothermic blood perfusions of isolated canine liver were undertaken to determine the most sensitive and reliable indicators of viability. Perfusate flow rates and arterial and portal venous pressures were monitored. Arterial and venous concentrations of potassium, pyruvate, serum glutamic oxaloacetic transaminase, and oxygen were monitored and the values stored on magnetic tape for computerized calculation of outputs. Continuous evaluation of taurocholate concentration in the perfusate allowed adjustment of infusion rate to provide a constant flow of bile across the hapatocytes. Pyruvate output, portal venous resistance, serum glutamic oxaloacetic transaminase output and potassium output provided the earliest indices of deterioration. Bile flow and oxygen consumption remained constant until irreversible outflow block had occured. The earliest and most constant parameter signaling deteoration of the ex vivo liver was pyruvate output. The deteriorating liver released pyruvate into the perfusate, while the functioning organ consumed or maintained the available substrate. Since pyruvate output occurs before the onset of irreversible damage, measures can be enacted to reverse the deterioration. Restoration of the preparation can be evaluated through the cessation of pyruvate output.

Animals↗