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Biomedical subjects

N L Mills

Publications and source records attributed to N L Mills.

At least 19 recordsLinked to original sources
PubMed1992

Comparative effects of endothelin (ET-1) and U46619 on human saphenous vein and gastroepiploic artery, sources of human autologous grafts.

The effects of endothelin (ET-1) on smooth muscle contractile activity were investigated and compared in human saphenous vein and gastroepiploic artery, vessels frequently used in revascularization procedures. ET-1 contracted saphenous vein and gastroepiploic artery in a concentration-dependent manner. The peptide produced a greater maximal effect in the vein than in the artery and, in both preparations, ET-1 was less efficacious than U46619, an agent which mimics the actions of thromboxane A2 at the thromboxane A2/prostaglandin H2 receptor. The contractile response to ET-1 declined spontaneously at a more rapid rate in the artery than in the vein. The present data indicate that ET-1 has significant contractile activity in both vessels which are used for coronary arterial bypass surgery and suggest that although, a weaker vasoconstrictor than U46619, the peptide could induce vasospasm in both graft vessels.

Arteries↗
PubMed1991

Technique for use of the inferior epigastric artery as a coronary bypass graft.

A search for a coronary bypass conduit with increased longevity has resulted in harvest of the inferior epigastric artery. The artery is dissected through a paramedian incision with retraction of the rectus muscle to the lateral side. As the inferior epigastric artery courses superiorly, it may lie in one of three positions in relation to the rectus muscle. Distal coronary anastomoses using this conduit are conventional, and the proximal anastomosis may be made to the aorta or end-to-side to an internal mammary artery or venous conduit. After preparation with dilute papaverine-Plasmalyte solution proximal sizes have ranged from 2.5 to 3.25 mm (internal diameter), and distal inferior epigastric artery sizes measured 1.5 to 2.5 mm (internal diameter). The lengths of the conduit ranged from 11.5 to 17.0 cm. Eighteen patients aged 41 to 74 years had inferior epigastric artery grafts to 19 coronary arteries. The indications for use were absent or poor-quality vein, young age with an attempt to limit vein graft, and avoidance of use of bilateral internal mammary artery grafts in insulin-dependent diabetic patients. There was one sterile wound hematoma and one late wound infection. There were no other infections and no deaths. Three patients studied postoperatively revealed widely patent inferior epigastric artery grafts.

Adult↗
PubMed1991

Preparation of the internal mammary artery graft with intraluminal papaverine.

Harvest of arterial grafts causes varying degrees of vascular spasm. Preparation of the internal mammary graft by intraluminal injection of diluted papaverine solution (60 mg of papaverine in 40 mL of normal saline) allows graft dilation to occur while pericardiotomy, cannulation, etc., is performed. Advantages are an increased mammary graft size with less chance of technical error, elimination of spasm with improved flow rates, and the identification of unclipped or uncauterized branches that may require reexploration. Newer vasodilating agents may prove even more effective in the future.

Coronary Artery Bypass↗
PubMed1991

Technical considerations for myocardial protection during the course of coronary artery bypass reoperation: the impact of functioning saphenous vein and internal mammary artery grafts.

New technical challenges involving the delivery of cardioplegia during the course of coronary artery bypass operation continue to be presented to the surgeon. Functioning saphenous grafts at reoperation that are at risk for distal embolization, are managed by altering the standard cardioplegia delivery techniques. Management of patent internal mammary artery (IMA) grafts depends upon the status of the native circulation and coronary collateral. The reoperation may be performed with a fibrillating heart, standard cardioplegia with a clamped mammary graft, or cardioplegia delivered during simultaneous circulatory arrest. Myocardial temperature measurements, during the course of more complex operations, are useful in choosing the appropriate technique for myocardial protection.

Collateral Circulation↗
PubMed1991

Atherosclerosis of the ascending aorta and coronary artery bypass. Pathology, clinical correlates, and operative management.

Analysis of 1735 patients who underwent coronary artery bypass grafting from January 1981 through December 1988 revealed 152 (8.8%) patients with mild (4.5%), moderate (2.2%), or severe (2.0%) atherosclerosis of the ascending aorta. Three distinct pathologic patterns were found. The prevalence of stroke in patients with the severe type of aortic disease prompted development of a new operative technique that has been used in 16 patients. It involves a "no-touch" technique of the ascending aorta whereupon the proximal saphenous vein anastomoses are performed end to side to internal mammary artery grafts. Ages ranged from 49 to 80 years (mean 68.9). The 16 patients had 62 distal artery and vein anastomoses and 26 proximal saphenous vein-internal mammary end-to-side anastomoses. Internal mammary artery free flows ranged from 130 to 420 ml/min. Two hospital deaths were unrelated to the technique. There have been no strokes or recurrences of angina. An inordinately high incidence of main left coronary disease (50%), significant carotid disease (79%), and abdominal aortic occlusive or aneurysm disease (93%) was discovered. Ascending aortic atherosclerosis must be suspected in all coronary bypass patients with associated significant carotid, abdominal aortic, and main left coronary artery disease, aortic wall irregularity on ascending aortic angiography, adhesions between the ascending aorta and its adventitia, pale appearance of the ascending aorta, and minimal bleeding of an aortic cannulation stab wound. A "no-touch" technique that avoids any manipulation of the ascending aorta and that uses the internal mammary arteries as the sole source of blood supply for coronary bypass is an effective method to prevent aortic clamp injury, "trash heart," or stroke from severe ascending aortic disease. Preoperative angiographic visualization of the ascending aorta of all patients undergoing coronary artery bypass is mandatory.

Aged↗
PubMed1990

Newer surgical techniques in myocardial revascularization.

Recent trends in the patient population coming for surgical treatment of coronary artery disease have prompted alterations in the type of coronary artery bypass surgery performed. Emphasis is placed on the more widespread use of arterial grafts and revascularization of vessels with extensive distal disease, utilizing endarterectomy techniques, in an attempt to provide a more complete and long-lasting revascularization.

Coronary Artery Bypass↗
PubMed1989

Technical considerations for use of the gastroepiploic artery for coronary artery surgery.

Disappointing long-term results with saphenous vein graft (SVG) for coronary bypass and excellent long-term results with internal mammary artery (IMA) to coronary bypass have prompted a search and research for other alternative coronary bypass conduits. Experience with the radial artery was disappointing due to early failure of those grafts. Likewise, conduits of artificial materials and homograft veins have not produced acceptable long-term results.

Arteries↗
PubMed1989

Preparation of the internal mammary artery graft. Which is the best method?

Early reports questioned the adequacy of flow of the internal mammary artery when used routinely as a bypass graft. "Adequate" mammary artery flow is now contested only in certain situations, that is, left ventricular hypertrophy, acute myocardial infarction, and reoperations. To compare the methods of mammary pedicle graft preparations with free mammary artery flow, we studied 31 patients who had the left internal mammary artery harvested for elective coronary artery bypass grafting. Group I comprised 14 patients whose mean body surface area was 1.91 m2. Systolic, diastolic, and mean arterial blood pressures, left atrial pressure, and heart rate were recorded and stabilized during flow measurements. Free flow of the internal mammary artery was measured before any pharmacologic manipulation and ranged from 5 to 44 ml/min (mean 18 ml/min). The grafts were sprayed and wrapped in sponges soaked in diluted papaverine solution (60 mg in 40 ml normal saline) for an average of 21 minutes. Free flow ranged from 10 to 108 ml/min (mean 51 ml/min). Intraluminal papaverine of the same dilution was then injected with hydrostatic dilatation. Immediate internal mammary artery flows rose from 150 to 333 ml/min (mean 229 ml/min). Group II comprised 17 patients who had internal mammary artery takedown under the exact conditions used in group I. Mean body surface area was 1.89 m2. Mammary artery pedicles were injected with diluted papaverine throughout their lengths with size 25 needles. After an average of 19.5 minutes, free flow ranged from 28 to 132 ml/min (mean 69 ml/min). Intraluminal diluted papaverine was then administered as in group I, and flows increased from 144 to 280 ml/min (mean 198 ml/min). The distal internal mammary arteries in both groups were 1.75 to 2.5 mm in internal diameter at the site of arteriotomy for flow measurement. This study shows that all mammary arteries are in spasm immediately after harvest and that flow is inadequate before any pharmacologic intervention. Although extraluminal vasodilators will increase free mammary artery flow, intraluminal papaverine followed by hydrostatic dilatation raises free flow to maximal capacity. Subsequent graft spasm has not been observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1978

Measurement of atrial septal defect during cardiac catheterization. Experimental and clinical results.

The size of experimental and clinical secundum atrial septal defects may be accurately measured during cardiac catheterization. The position of the defects in the septum and their distance from the aortic and mitral valves may also be ascertained. A balloon catheter inflated with radiopaque dye is used for the measurement. The volume of dye in the balloon has been correlated with its maximal diameter. Thus, a no. 8-10 French catheter filled with 10 ml of diatrizoate (50 percent) has a diameter of approximately 25 mm and a no. 8-22 French catheter filled with 40 ml of diatrizoate a diameter of approximately 43 mm. Persistent arrhythmias or other adverse effects of the procedure were not observed. There was a high correlation between balloon-measured atrial septal defects and those measured at necropsy in the animals or at operation in the patients. These measurements aid in determining whether an ostium secundum defect is of proper size and location to be closed transvenously and may also prove valuable in physiologic studies of atrial septal defects or other cardiac anomalies.

Adolescent↗
PubMed1978

The internal mammary bypass graft: a superior second coronary artery.

In a study of the initial 1,004 consecutive patients who had direct coronary artery bypass at Ochsner Medical Institutions, computer methods of data processing were used to compare the clinical results between patients who had saphenous vein (SV) grafts and those who had internal mammary artery (IMA) grafts. The factors compared were the long-term mortality rates, nonfatal myocardial infarction rates, relief or persistence of angina, and the percentage of patients who acquired congestive heart failure. A simple comparison showed the patients with IMA grafts did better in all four categories; however, in a subsequent analysis in which maldistributed factors were removed, the rates of anginal relief and congestive heart failure were not significantly improved. The major benefit appears to be an increase in longevity among patients who had IMA bypasses.

Aged↗
PubMed1978

Renal artery stenosis and polycystic kidney disease.

A patient had unilateral renal artery stenosis and, at the same time, bilateral polycystic kidney disease. The renal venous renin ratio of 151:40, together with a high peripheral plasma renin activity, indicated that the hypertension was partially caused by renopressor mechanism. Correction of the obstructive lesion permitted a better control of hypertension with antihypertensive drugs, and the peripheral and renal venous renin activity returned to normal. The success in detecting one pathogenic mechanism responsible for arterial hypertension should not deter further diagnostic efforts.

Adult↗
PubMed1977

Combined procedure of coronary artery bypass grafting and valve repair.

The safety of combined operative procedures for valvular and coronary artery disease was reviewed in 27 patients. Twelve patients had aortic valve disease and 15 had mitral valve disease. Forty-seven coronary artery reconstructions were performed, and average of 1.7 per patient. Twenty-two patients underwent valve replacement and 5 had valvuloplasty. Congestive heart failure was the major symptom in 20 patients, and angina was the major symptom in 7. Eight of the patients with congestive heart failure had no angina, but significant coronary stenoses were demonstrated at routine coronary angiography. Coronary reconstruction was performed before valve repair. Two patients died postoperatively (a hospital mortality of 7.4%), and there were 4 late deaths from 2 to 28 months postoperatively. There were no postoperative myocardial infarctions. Contrary to previous reports, coronary artery reconstruction and valve repair need not be associated with an increased risk. Protection of the myocardium by coronary perfusion through reconstructed coronary arteries enables valve repair to be done without greater risk than valve repair alone. All patients considered for valve repair should have coronary angiography.

Adult↗