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Biomedical subjects

K W McNicholas

Publications and source records attributed to K W McNicholas.

At least 19 recordsLinked to original sources
PubMed2002

Clipping of cerebral aneurysm under hypothermic cardiac arrest and simultaneous coronary artery bypass grafting: case report.

This report describes a case where joint neurological and cardiac surgery teams cooperated to perform simultaneous procedures of clipping a complex internal carotid artery under hypothermic cardiac arrest and coronary artery bypass grafting. A 69 year old man was evaluated for complaints of double vision, pain behind his right eye, and progressively worsening headaches. Examination showed bilateral upgoing toes and difficulty performing a tandem gait. The patient had a history of myocardial infarction. Brain MRI showed a 1.6 cm diameter, partially thrombosed aneurysm of the right internal carotid artery and posterior communicating artery. Cardiac catheterisation showed critical coronary artery disease of the distal segment of the right coronary artery with 90% stenosis of the midcircumflex artery and an ejection fraction of 40%. After initial exposure of the aneurysm, the cardiac team instituted hypothermic cardiac arrest (21 degree C). The aneurysmal sac was collapsed and dissected from the surrounding perforators. An encircling fenestrated clip was applied and a small part of the neck of the aneurysm was further clipped with straight clips. The cardiac surgery team performed the coronary artery bypass grafting procedure. The patient recovered fully, returned to his normal activities, and is functioning independently.

Aged↗
PubMed1998

Mediastinal lipoblastoma involving the left innominate vein and the left phrenic nerve.

Lipoblastoma, a rare tumor of childhood, was first described by Vellois and associates in 1958. The extremities are the most common location for this tumor. Mediastinal lipoblastoma is exceedingly rare, with only four cases reported in the English-language literature. The authors report a case of mediastinal lipoblastoma in a 6-year-old girl, which, in contrast to previously reported cases, presented late in childhood and included sacrifice of the left innominate vein and phrenic nerve for successful resection.

Brachiocephalic Veins↗
PubMed1998

Intravenous insulin infusion therapies for postoperative coronary artery bypass graft patients.

BACKGROUND: Hyperglycemia is very common in postoperative coronary artery bypass graft patients. Although sliding scale insulin therapy is often used, there is no standard of care for the management of hyperglycemia. METHODS: Different intravenous insulin therapies were used in three consecutive sets of hyperglycemic postoperative coronary artery bypass graft patients. The first method was a sliding scale intravenous insulin regimen beginning with four units/hr, and increasing by four units/hr each hourly bedside arterial whole blood glucose measurement greater than 250 mg/dL (13.9 mmol/L) (n = 58). The second and third methods were constant insulin infusions at a rate of eight units (n = 60) and 20 units/hr (n = 51) respectively. Insulin infusions were reduced to two units/hr when the glucose concentration decreased to 150-250 mg/dL (8.3-13.9 mmol/L), and was stopped when it fell below 150 mg/dL (8.3 mmol/L). RESULTS: Thirty percent of patients undergoing coronary artery bypass grafting had a diagnosis of diabetes mellitus. Forty-eight percent of all patients had a glucose value greater than 250 mg/dL (13.9 mmol/L) within the first 24 hours postoperatively. The three intravenous insulin infusion regimens produced similar control of arterial whole blood glucose concentrations. Patients with high initial glucose concentrations (greater than 400 mg/dL) (22.2 mmol/L) required intravenous insulin therapy for ten or more hours before attaining the target range of 151-250 mg/dL (8.3-13.9 mmol/L). CONCLUSIONS: Constant-rate intravenous insulin therapy is effective in lowering arterial whole blood glucose concentrations in postoperative coronary artery bypass graft patients. Initiation of intravenous insulin therapy at lower glucose values reduces the time necessary for the infusion.

Coronary Artery Bypass↗
PubMed1996

Atrial blood cyst: a rare finding.

Blood cysts of the heart, benign cardiovascular tumors, are extremely rare in adults. Our literature search found fewer than 20 such cases that have been reported in the past 30 years, all of which involved either the cardiac valves or the left ventricle. This case report describes a 72-year-old man with a right atrial tumor that was found to be a simple blood cyst.

Aged↗
PubMed1994

Lunular hypertrophy and aortic valve disease.

Cuspid malcoaptation secondary to abnormal hypertrophy in combination with stiffening involving the line of apposition (lunular hypertrophy) has not been recognized as a cause of aortic valve dysfunction. This entity was found in 50 adults (mean age, 62 years). Thirty-three had pure aortic valve insufficiency (> or = 3+, n = 13; < 3+, n = 20), 13 had mixed aortic valve insufficiency and stenosis (> or = 3+, n = 2; < 3+, n = 11), and 4 had pure aortic valve stenosis. Forty-one had a history of rheumatic heart disease and advanced mitral valve disease, and 7 had coronary artery disease. All underwent shaving of the hypertrophic protuberances, which in 26 patients constituted the entire aortic valve repair. In the remaining 24 patients, aortic valve repair included one or more additional procedures; there were 15 commissurotomies, 12 debridements of calcium deposits from the base of the cusps, and 5 cusp resuspensions. Concomitant mitral valve repair was performed in 26 patients, mitral valve replacement in 15, tricuspid valve repair in 11, coronary artery bypass grafting in 7, and repair of an ascending aortic aneurysm in 2. In 2 patients, the attempt to repair the aortic valve was unsuccessful, necessitating valve replacement. There were 5 operative deaths (10%), but none were related to aortic valve repair. Forty-three patients entered follow-up (mean, 56 +/- 57 months). Three patients (7%) suffered late recurrent aortic valve insufficiency (at 6, 48, and 72 months). The remaining 40 patients (93%) had trivial or no recurrent aortic valve dysfunction. The 6-year actuarial freedom from aortic valve-related problems was 92%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Innominate artery compression of the trachea: relationship to cervical herniation of the normal thymus.

PURPOSE: To document the possible association of segmental tracheomalacia in the thoracic inlet with the combination of a large thymus and normal innominate artery. MATERIALS AND METHODS: Eight infants with symptoms of innominate artery compression of the trachea were studied. The diagnostic approach included observation of posterior tracheal displacement and focal tracheal collapse at fluoroscopy, ablation of the right radial pulse by rigid endoscopic pressure, and compression of the anterior tracheal wall by the innominate artery at magnetic resonance imaging. RESULTS: Six patients had relief of symptoms with either thymectomy and innominate artery reimplantation (n = 4) or subtotal thymectomy and innominate artery suspension (n = 2). The ratio of the sagittal diameter of the thymus to the sagittal diameter of the thoracic inlet was significantly (P < .0009) higher in the symptomatic patients (0.58 +/- 0.03) than in age-matched control subjects (0.35 +/- 0.08). CONCLUSION: Crowding of the thoracic inlet by cervical herniation of an enlarged but normal thymus may contribute to the development of tracheomalacia and the symptoms of innominate artery compression.

Brachiocephalic Trunk↗
PubMed1993

Cervical trachea: dynamics in response to herniation of the normal thymus.

Nineteen infants aged 2 months to 2.5 years, first seen predominantly with stridor, were noted to have intermittent soft-tissue mass effect in the upper airway during routine evaluation with fluoroscopic or radiographic methods. The cervicothoracic trachea was always buckled posteriorly and, in almost all instances, to the right during forced exhalation (crying). Real-time ultrasound examination with the neck extended was used in these patients to define the cause of the tracheal dynamics. The intermittent cephalic movement of the homogeneous echotextured thymus from the anterior mediastinum into the neck was determined to be the probable cause of the mass effect in these infants. Magnetic resonance imaging in three infants confirmed this finding. The intermittent, physiologic suprasternal movement of the thymus in these infants did not by itself cause any luminal compromise of the trachea and did not result in any respiratory difficulty in these infants.

Child, Preschool↗
PubMed1992

Repair of traumatic rupture of the aortic valve.

Traumatic aortic valve rupture is a rare complication of nonpenetrating cardiac injury and can be caused by a tear or avulsion of the valve. The most common method of treatment has been valve replacement, although valve repair has been successful in a few cases of cusp tear or detachment. We report a case of aortic valve commissural avulsion in which a reparative technique was applied and the natural valve was preserved.

Aortic Valve↗
PubMed1991

Hypertrophy of nodules of Arantius and aortic insufficiency: pathophysiology and repair.

Aortic insufficiency (AI) due to fibrosis and thickening of the nodules of Arantius in the otherwise normal aortic valve was found in 11 adults (age range, 41 to 65 years) between 1976 and 1988. Nine had concomitant mitral stenosis; 2 had coronary artery disease. In 6 patients AI was graded 3+ or greater; in 5 it was less than 3+. Correction of AI and restoration of cuspid flexibility and apposition by shaving the hypertrophied nodules was accomplished in all, with postrepair AI graded as 1+ or less. There was one hospital death, a patient who had prior mitral operation. Mean follow-up was 68 +/- 56 months. Only 1 patient had late (6 years) recurrent serious (3+) AI. Nine continued to have 1+ or less AI, based on echocardiography or catheterization (n = 6) or on physical examination performed at a mean of 74 months. We conclude that thickening of the nodules of Arantius may cause AI. Long-term correction can be accomplished by sculpturing of the involved cusps.

Adult↗
PubMed1991

Comparative efficacy of cimetidine, famotidine, ranitidine, and mylanta in postoperative stress ulcers. Gastric pH control and ulcer prevention in patients undergoing coronary artery bypass graft surgery.

To determine the comparative efficacy of several histamine (H2)-receptor antagonists (cimetidine, famotidine, and ranitidine) and the antacid Mylanta-II (Stuart Pharmaceuticals, Wilmington, DE) in gastric pH control and the prevention of postoperative stress ulceration, a prospective, randomized study was performed in a homogeneous population of patients with elective coronary artery bypass. None of the 57 patients in the study population had a documented history of ulcer disease. There were four treatment groups, each with similar demographics (age and sex). Cimetidine-treated group consisted of 15, famotidine-treated group of 18, ranitidine-treated group of 19, and antacid-treated group of 5 patients. There was no hemodynamically significant postoperative gastrointestinal bleeding in any of the patients. When the agents were compared for efficacy of gastric pH control, statistically better pH control was found in the famotidine- and ranitidine-treated groups (P less than 0.003) than in the cimetidine-treated group (pH less than or equal to 4.0) during the 20-hour observation period. Side effects (hematologic and neurological) were noted only in the cimetidine-treated group. The results of this study indicate that in patients in postoperative intensive care, better gastric pH control, and thus prevention of gastric stress ulcers, is achieved with either famotidine or ranitidine rather than cimetidine or antacid.

Aged↗
PubMed1990

Sutureless ring graft replacement of ascending aorta and aortic arch.

Complications after aortic replacement that result from prolonged graft insertion time and technical difficulties with suturing through friable, diseased aortic tissue can be addressed with use of the sutureless intraluminal ring graft. Between 1978 and 1989, we replaced the ascending aorta or aortic arch with this device in 49 patients. At no time were we unable to use a sutureless graft during a procedure. Twenty-eight cases of aneurysmal disease and 21 cases of acute or chronic dissection were treated. Twenty-six patients required replacement of the aortic valve, with annuloartic ectasia being the most common indication (71%). Ten patients underwent concomitant coronary artery bypass grafting. The operative mortality rate for ascending aortic aneurysm repairs was 4%, and that for dissections was 18%. Five of 8 patients requiring aortic arch replacement survived. Most patients were studied angiographically before discharge. No complications were related to anastomotic hemorrhage, pseudoaneurysm formation, graft migration, or thromboemboli. Individual cases of phrenic nerve palsy, acute tubular necrosis, and transient ischemic attack, all of which resolved completely, were identified. The actuarial 5-year survival rate is 64%. We conclude that modification of the sutureless intraluminal ring graft to suit the pathology encountered at operation allows the quickest repair with the least chance of anastomotic complication.

Adolescent↗
PubMed1989

Replacement of the descending thoracic aorta with intraluminal ring graft.

Renal failure and paraplegia are major complications of operations on the descending thoracic aorta. To minimize cross-clamp time and reduce the incidence of such complications, we have used an intraluminal ring graft to reestablish aortic continuity in patients with descending thoracic aortic lesions. From March 1978 to December 1986, we used this technique alone in 28 patients. There were 4 patients with traumatic aortic disruptions, 4 with dissections, 4 with expanding aneurysms, 2 with ruptured aneurysms, 1 with Marfan's syndrome, and 13 with atherosclerotic aneurysms that were repaired electively. The cross-clamp times ranged from 4 to 28 minutes. There were three early postoperative deaths (within 30 days) and one late postoperative death in the follow-up period (mean, 28.2 months). Ring dislodgement occurred only once, in the first patient in this series. There were no instances of postoperative renal failure or paraplegia. We conclude that the use of an intraluminal ring graft greatly reduces the aortic cross-clamp time and is a safe and effective technique.

Adolescent↗
PubMed1989

A ten-year experience with bacterial aortitis.

Twenty-one patients with bacterial aortitis were treated in four institutions over a 10-year period. Clues to the diagnosis were a pulsatile mass; fever; positive blood culture; CT scan revealing aortic nodularity, an aneurysm of irregular configuration, or air in the aortic wall; and angiography revealing a lobulated aneurysm. The most commonly identified organisms were Salmonella and Staphylococcus. Excision with in situ repair was performed in nine patients; 11 patients underwent extraanatomic bypass grafting with aortic ligation. In situ graft repair was performed when the infected aorta could be removed entirely or when the thoracic or suprarenal aorta was involved. Axillofemoral bypass grafting was used when infection was extensive. There were eight disease-related deaths. No graft infections were encountered in patients who survived.

Aged↗
PubMed1989

Ebstein's anomaly: unusual presentation and surgical repair.

Ebstein's anomaly is the most significant congenital anomaly involving the tricuspid valve. This lesion may present in a simple form or may be complicated by other lesions. Patients with this anomaly may vary from mildly symptomatic to severely debilitated. The role of surgical treatment is not uniformly agreed upon, and the optimal procedure for correction or palliation is not clearly defined. Because of the wide spectrum of morphologic abnormalities which may be present in Ebstein's anomaly, no one particular operation may always be satisfactory. We and other groups continue to search for optimal procedures and feel strongly that individualization must be carried out to optimize the result in each patient. We encountered a patient with Ebstein's anomaly in an almost atretic tricuspid valve. In addition, there was severe right ventricular outflow tract obstruction and pulmonary valve stenosis. In this patient the "Fontan Principle" was successfully applied in his management.

Child↗
PubMed1988

High frequency, high volume ventilation for right ventricular assist.

During ventilation, the lungs may serve as accessory pumps for forward blood flow. We have noted significant hemodynamic improvement in several patients during short periods of vigorous hand ventilation with the Ambu bag and tried to reproduce the hemodynamic improvement in the management of four patients with profound low cardiac output syndrome secondary to right ventricular (RV) failure following open heart surgery. High frequency, high volume (HFHV) ventilation resulted in improved hemodynamics in these patients, as evidenced by pulsatile pulmonary blood flow and increased cardiac output. Right-sided stroke work was present and there was a fall in mean central venous pressure (CVP) and rise in mean pulmonary artery pressure (PAP).

Assisted Circulation↗