The healing characteristics of autogenous saphenous vein used in the reconstruction of previously implanted arterial saphenous vein grafts

Aortocoronary saphenous vein grafts with early isolated stenoses pose the technical problem of how to deal with these grafts at reoperation. The advisability of using a portion of old graft when reconstructing these grafts was examined. An experimental model was devised in which the anatomical and pathological interfaces between fresh vein and previously inserted vein were studied. Superficial femoral artery from the thigh of 15 dogs was replaced by reversed autogenous saphenous vein. Four months later, the animals were divided into two groups. Group 1 consisted of 8 animals that underwent transection and reimplantation of the middle 4 cm of the vein graft in exactly the same position in which it had been. In Group 2, the 7 animals had the middle 4 cm of the graft replaced with newly harvested reversed saphenous vein. Six months after initial vein graft implantation, the animals were studied. No critical stenoses were seen in the grafts. Pathological study of Group 1 grafts revealed fibrous graft disease of uniform severity throughout the graft, thereby demonstrating that new anastomoses in an old graft do not affect graft disease. Group 2 grafts revealed that the severity of disease in the new interposed segment of the vein graft was less than in the old retained portions of the graft. No untoward reaction causing acceleration of graft disease occurred between old and new vein. Operations using undiseased portions of old vein grafts should be considered a viable option in repeat coronary revascularization for early stenoses.

Fuel-stimulated insulin secretion by clonal hamster beta-cell line HIT T-15

Insulin secretion by monolayer cultures of HIT T-15 cells was measured in response to various fuel molecules (glucose, dihydroxyacetone, lactate, glutamine, alpha-ketoisocaproic acid, alpha-ketoisovaleric acid) and a nonmetabolized glucose analogue (3-O-methylglucose). HIT cells secreted insulin in response to fuel molecules, but 3-O-methylglucose was ineffective. Stimulation of insulin release by fuels was increased by isobutylmethylxanthine and blocked by antimycin A. Iodoacetate selectively inhibited glucose-stimulated insulin release but had little effect on alpha-ketoisocaproic acid-stimulated insulin secretion. These results indicate that HIT cells retain the capacity of normal beta-cells to act as fuel sensors. Thus, HIT cells may provide a well-defined and relatively abundant tissue source in studies of stimulus-secretion coupling in beta-cells stimulated by fuels.

Glucose transport by radiation-induced insulinoma and clonal pancreatic beta-cells

Sugar uptake was measured in dispersed cells prepared from radiation-induced insulinomas transplantable in NEDH rats and in three clonal beta-cell lines maintained in continuous culture (RIN m5F, RIN 1046, HIT). Uptake of D-glucose and 3-O-methyl-D-glucose by insulinoma cells was rapid so that the intracellular concentration of D-hexoses approximated the concentration in the incubation medium by 15-30 s. L-Glucose was taken up only slowly. 3-O-methyl-D-glucose uptake by RIN m5F, RIN 1046, and HIT cells was slow; with 1 mM 3-O-methylglucose in the medium, equilibrium was attained at 20 min, but with 10 mM 3-O-methylglucose, equilibrium was not attained even at 20 min. In HIT cells incubated with D-glucose for 30 min, the intracellular concentration of glucose was less than the medium glucose concentration, indicating glucose transport is a nonequilibrium reaction in this cell line. These data indicate that radiation-induced insulinoma cells retain the capacity of normal beta-cells to transport sugar at high rates. RIN m5F, RIN 1046, and HIT cells transport sugar slowly, however, and thus differ from normal beta-cells. In RIN m5F, RIN 1046, and HIT cells, unlike in normal beta-cells, glucose transport may be the site regulating glucose metabolism.

Acetylcholine stimulates glucose metabolism by pancreatic islets

Acetylcholine stimulates insulin secretion in the presence of physiological concentrations of glucose. Stimulation of insulin secretion by acetylcholine is accompanied by an increase in glucose usage by isolated rat islets. Acetylcholine increased glucose usage by 38%, 28%, and 12% at 3.5 mM, 5.5 mM, and 10 mM glucose, respectively, compared to glucose usage by isolated islets incubated with glucose alone. Data showing increased glucose usage in islets treated with acetylcholine converge with data from an earlier report (J. Biol. Chem. 254 3921-3929 [1979]) showing a crossover point for glycolytic metabolites at phosphofructokinase to indicate that activation of glycolysis by acetylcholine results from increased phosphofructokinase activity and coordinate activation of hexokinase in intact islets.

Identification of glucokinase as an alloxan-sensitive glucose sensor of the pancreatic beta-cell

Alloxan inactivated glucokinase in intact, isolated pancreatic islets incubated in vitro. Inactivation of glucokinase was antagonized by 30 mM glucose present during incubation of islets with alloxan. Glucokinase partially purified from transplantable insulinomas or rat liver was inactivated by alloxan with a half-maximal effect at 2-4 microM alloxan. Inactivation of purified glucokinase was antagonized by glucose, mannose, and 2-deoxyglucose in order of decreasing potency but not by 3-O-methylglucose. Glucose anomers at 6 and 14 mM were discriminated as protecting agents, with the alpha-anomer more effective than the beta-anomer. Glucokinase was not protected from alloxan inactivation by N-acetylglucosamine, indicating that the reactive site for alloxan is not the active site; therefore, glucose may protect glucokinase by inducing a conformational change. Glucokinase is thought to be the glucose sensor of the pancreatic beta-cell. The finding that glucokinase is inactivated by alloxan and protected by glucose with discrimination of its anomers similar to inhibition of glucose-stimulated insulin secretion by alloxan supports this hypothesis and appears to explain the mechanism for inhibition of hexose-stimulated insulin secretion by this agent and the unique role of glucose and mannose as protecting agents.

Regulatory role of fructose-2,6-bisphosphate in pancreatic islet glucose metabolism remains unsettled

Fructose-2,6-P2 was measured in perifused, isolated rat pancreatic islets. Fructose-2,6-P2 was present in pancreatic islets at low levels approximately equal to fructose-2,6-P2 content of liver from fasted rats. In islets perifused with glucose at physiologic concentrations, fructose-2,6-P2 was increased from 0.8 microM in the presence of 5.5 mM glucose to 1.0 microM at 10 mM glucose and 1.3 microM at 16.7 mM glucose, but did not increase further at higher glucose concentration. Therefore, only modest increases in the phosphofructokinase-1 activator, fructose-2,6-P2, occur at glucose concentrations stimulating insulin secretion.

Neurological complications of coronary revascularization

In a series of 3,206 consecutive coronary artery bypass procedures performed between 1976 and 1981, 89 patients died (2.8% mortality) and 32 patients (1%) suffered major neurological syndromes. Among the latter patients, four distinct groups were identified. Group 1 consisted of 10 patients who remained unresponsive after operation. In Group 2 were 10 patients who awakened after operation but had clinical evidence of focal cerebral infarction. Group 3 included 6 patients who were initially intact neurologically but in whom neurological deficits later developed. In Group 4 were 6 patients who had severe mental aberration but no focal neurological deficits. The incidence of coma or focal deficit occurring without a lucid interval (Groups 1 and 2) was 0.62%, and these patients had a 30% mortality. Causative factors were suspected in 70% of the patients in Groups 1 and 2, and included atheromatous embolism, perioperative hypotension, carotid artery occlusive disease and air embolism. The outcome was poor for unresponsive patients, with 70% dying or remaining comatose, but nearly all of the patients with focal deficits or severe mental aberration demonstrated notable improvement.

Coronary revascularization in septuagenarians

Despite a 15 year experience with the aorta-coronary bypass operation, indications for its use remain unsettled, especially in the elderly. Between January, 1974, and June, 1980, 2,667 patients underwent coronary artery revascularization with an overall mortality of 3.8% (101/2,667). During the last 12 months the mortality has decreased to 1%. There were 2,562 patients below the age of 70, with a mortality of 3.5% (90/2,562), in contrast to 105 patients over the age of 70, with a mortality of 10.5% (11/105) (p = 0.002). In patients less than 70 years of age there was a significant difference between the mortality of men, 3.12% (67/2,146), and that of women, 5.53% (23/416) (p = 0.015). This disparity of operative risk was far more pronounced in patients over 70 years of age: men 6% (5/84) and women 28.6% (6/21) (p = 0.002). The overall operative mortality of women, 6.6% (29/437), was significantly different from the overall mortality of men, 3.2% (72/2,230) (p = 0.001). An in depth analysis of past medical history, risk factors, and catheterization data is presented in those patients over the age of 70. The average number of vessels bypassed was 2.40: men 2.47 and women 2.09 (p = NS). The ages varied from 70 to 81 years with a mean of 72.5. Smoking (p = 0.012) and diabetes (p = 0.0078) were significant risk factors for coronary disease. Smoking (p = 0.032) and abnormal pulmonary artery pressures (p = 0.0429) were significant variables affecting mortality. A 97.1% follow-up was obtained up to 78 months. Coronary artery revascularization can be performed in men below the age of 70 with acceptable mortality, but there is a twofold increase above the age of 70. Women can undergo revascularization below the age of 70 with a significantly higher risk than males. Those above the age of 70 are at severe risk and should undergo revascularization only after careful selection.

Chromatographic resolution and kinetic characterization of glucokinase from islets of Langerhans

Glucokinase (ATP:D-glucose 6-phosphotransferase, EC 2.7.1.2) from rat islets of Langerhans was partially purified by chromatography on DEAE-Cibacron blue F3GA agarose. The enzyme eluted in two separate peaks. Sigmoidal rate dependence was found with respect to glucose (Hill coefficient = 1.5) for both enzyme fractions. Km values for glucose were 5.7 mM for the major fraction and 4.5 mM for the minor fraction. Neither fraction phosphorylated GlcNAc. A GlcNAc kinase (ATP:2-acetamido-2-deoxy-D-glucose 6-phosphotransferase, EC 2.7.1.59)-enriched fraction, prepared by affinity chromatography on Sepharose-N-(6-aminohexanoyl)-GlcNAc, had a Km of 25 microM for GlcNAc. Islet tissue also contained hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) eluting in multiple peaks. The results are consistent with the concept that glucokinase serves as the glucose sensor of pancreatic beta cells.

Reflections in a normal eye: the effect of aortic stenosis on oculopneumoplethysmography

The association of aortic stenosis and syncope is well recognized. Oculopneumoplethysmography (OPG) can provide an accurate index of carotid stenosis and indirectly measure cerebral perfusion. The possibility that OPG would be influenced by aortic valve disease was assessed in patients prior to valve replacement. 31 patients were studied. 19 patients had aortic stenosis (AS), 3 had aortic insufficiency (AI), and 10 had mixed lesions. OPG was positive in 15 patients (48%). Considering all forms of aortic valve disease, the likelihood that a positive OPG was indicative of AS with a gradient of greater than 60 mmHg was significant (P = .002). Of 18 patients with AS alone, no patient with a valve gradient greater than 60 mmHg had a negative OPG (P = .0001). OPG became normal in 11 of 12 patients restudied postoperatively. Critical aortic stenosis results in uneven distribution of blood flow into the brachiocephalic vessels. OPG accurately identifies this effect which becomes evident at aortic valve gradients greater than 60 mmHg.

Diaphragmatic left ventricular aneurysm. Clinical features, surgical treatment, and long-term follow-up in 22 patients

Although the formation of a left ventricular aneurysm (LVA) is a common and well-recognized complication of myocardial infarction (MI), diaphragmatic LVA is a rare clinical entity. Of 354 consecutive patients who underwent LVA resection, we describe the clinical features and surgical results of 22 patients (6%) with diaphragmatic LVA. All patients had a history of MI. The principal clinical indication for surgery was heart failure in nine patients, angina pectoris in ten patients, and recurrent ventricular tachycardia unresponsive to medical therapy in three patients. A ventricular septal defect was present in two patients, and moderate to severe mitral regurgitation was present in four patients. Three of the four surgical deaths (operative mortality, 18%) occurred in patients with mitral regurgitation or with ventricular septal defect. Eleven patients are alive at a mean follow-up of 40 months. Six of them are asymptomatic and two have angina at a higher level of physical activity than before surgery. Notable differences exist in the clinical presentation and surgical findings between patients with diaphragmatic and anterior LVA.

Acute ascending aortic dissection: surgical management

The success of total aortic root replacement in conditions such as annuloaortic ectasia and complicated redo surgery has stimulated its use in acute dissection of the ascending aorta. We believe this radical approach is, in most cases, unwarranted, considering the excellent results with valve conservation. From 1970-1978, 20 consecutive patients with acute anterior aortic dissection and aortic insufficiency were operated at Rush-Presbyterian-St. Luke's Medical Center. Only one patient (5%) required reoperation for hemorrhage. The three operative deaths (15%) were associated with right coronary artery disruption, aortic-right atrial fistula and preoperative intrapericardial false lumen rupture. In eight patients, valve resuspension was combined with primary aortic repair and nine with ascending graft interposition, but aortic valve replacement was required in three because of annuloaortic ectasia or tissue friability. One patient treated by primary repair in 1971 underwent successful reoperation for redissection 7 years later (1.4% per patient-year risk of late reoperation), but the remaining 16 patients, followed 2-10 years, remain free of aortic insufficiency or recurrent aneurysm. This experience supports the use of valve reconstruction rather than replacement in most cases of acute anterior dissection of the aorta.

Coarctation of the aorta: four unusual instances

Four unusual instances of coarctation of the aorta are presented. Three coarctations were located proximal to the left subclavian artery, and the other was in the normal location with a patent ductus arteriosus and an anomalous distal right subclavian artery. Unusual coarctations can be identified on physical examination on the basis of variations of blood pressure and pulses in the upper extremities. Unilateral rib notching may be noted on chest roentgenogram, and an aortogram can delineate its exact location. Four separate means of surgical repair are described.

Leg wound complications associated with coronary revascularization

One percent of 2,545 patients undergoing coronary revascularization with the saphenous vein over a 5 year period sustained leg wound complications which necessitated extra care. Fourteen complications were minor and required only drainage, a new antibiotic, and dressing changes. Thirteen major wound complications required wide debridement and, of these, five could be closed only with skin grafts. Eight wounds were infected, two with Staphylococcus aureus and six with mixed gram-negative flora. Ninety-three percent of these wounds were in the thigh. Average weight of patients with leg wound complications was 73.5 +/- 3.5 kg and not different from that of a randomly selected control group (73.8 +/-1.2 kg). However, 40% of the patients were women, a much higher incidence than control (p less than 0.005). Hospital stay increased significantly from 12.1 +/- 0.5 days for the control group to 24 +/- 2.6 days for the group with wound complications (p less than 0.005). Average hospital stay was 33.6 +/- 3.8 days (p less than 0.001) in those patients with major wound complications (estimated hospital cost $9,900). Leg wound complications of saphenous vein harvest are infrequent but serious. Efforts to prevent this complication should include minimal dissection, careful hemostasis, and closure in layers. Development of skin slough, infection, and necrosis necessitating débridement and drainage is a major and expensive complication. Wide excision and direct closure are necessary to minimize hospital stay and reduce the requirement for skin grafting.

Sternal wound complications. Management and results

Of 4,124 patients undergoing median sternotomy for cardiac operations, 1.8% had sternal wound complications. These included wound drainage, skin separation, unstable sternum, and sternal dehiscence with or without infection. Septicemia and mediastinal abscess were found in all 19 patients who died. Incision and drainage of skin and subcutaneous tissue with frequent changes of dressing or irrigation (Method A) is recommended for those patients with (I) serosanguineous drainage only or (2) a stable sternum and superficial infection without systemic reaction. Surgical débridement of the sternum and mediastinum with reclosure followed by mediastinal irrigation via drainage tubes with 0.5% povidone-iodine solution (Method B) is recommended for patients with (1) a draining, unstable sternum, (2) infection involving the retrosternal space, or (3) infection causing a systemic reaction unresponsive to Method A. None of the eight patients in the latter group with more serious infections died when managed by Method B, and only one had recurrent infection. In contrast, of 28 patients of the latter group not treated with Method B, 11 died of infection-related causes and 13 returned with recurrent infection.

Simultaneous aortic and renal artery reconstruction

From 1970 to 1978, 39 patients underwent simultaneous aortic and renal artery reconstruction. Of these, 37 had severe single or bilateral renal lesions in combination with an aortic aneurysm, or symptomatic or asymptomatic aortoiliac disease. Two patients had renal arteries that originated from an abdominal aortic aneurysm. Thirty-two patients were hypertensive, one had chronic renal failure, and three others had asymptomatic renal lesions that were bypassed prophylactically. Operations performed included aortic replacement plus: single renal graft; bilateral renal grafts; renal graft plus contralateral nephrectomy; and renal graft plus mesenteric revascularization. All early postoperative deaths (four) occurred in patients with aneurysmal disease. Twenty-nine patients were available for long-term evaluation. In patients who were hypertensive preoperatively, 64.0% experienced long-term cure or improvement. Cardiac and cerebral disease, lower extremity claudication, and the need for subsequent cardiovascular surgery occurred with substantial frequency during the follow-up period.

Requirements for a method of transvenous inferior vena cava interruption

Six requirements were defined that would characterize a safe and effective technique of transvenous inferior vena cava (IVC) interruption: (1) the instrument should be placed transjugularly under local anesthesia; (2) the instrument should have "built-in" capability for venography; (3) the technique should produce complete occlusion of the IVC; (4) the occluder must adapt to any variable in IVC diameter; (5) the intracaval device must have no sharp edges, pins, or points; and (6) the technique must permit simultaneous heparin therapy. These specifications were met by a catheter-delivered detachable balloon that could be inflated to any needed diameter. This technique was used in 96 patients, with a follow-up period to ten years. Time and experience confirm the validity of the six requirements for a safe and effective technique.