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Biomedical subjects

D C Miller

Publications and source records attributed to D C Miller.

At least 325 records · Page 18Linked to original sources
PubMed1985

Determinants of operative mortality for patients undergoing aortic valve replacement. Discriminant analysis of 1,479 operations.

The influence of 35 preoperative and intraoperative characteristics on operative mortality risk after 1,479 isolated aortic valve replacement procedures (1967 to 1981) was investigated utilizing univariate and multivariate logistic regression analyses. Mean age at operation was 58 +/- 13 years; 72% of patients were men. Physiology was classified as aortic stenosis (58%), regurgitation (30%), or both (9%). The overall operative mortality rate was 7% +/- 1%, but there were substantial differences in operative mortality rates among physiological subgroups (aortic regurgitation, 10% +/- 2%; aortic stenosis, 6% +/- 1%; stenosis/regurgitation, 5% +/- 2%). Independent determinants of operative mortality rate in the entire group were advanced New York Heart Association functional class, renal dysfunction, physiological subgroup, atrial fibrillation, and older age. In the aortic regurgitation subgroup, functional class, atrial fibrillation, and operative year were independent predictors. In the aortic stenosis subgroup, the significant determinants were functional class, renal dysfunction, age, prosthetic valve dysfunction, and absence of angina. Concomitant coronary bypass grafting, previous operation, endocarditis, and ascending aortic replacement had no independent predictive effect on operative mortality rate. Thus, the early results of aortic valve replacement can be related to several specific variables describing the functional and physiological status of the patient. Operative mortality rate is not independently related to previous operation or concomitant operative procedures. Specific differences in risk factors exist among the various physiological subgroups, probably reflecting the pathophysiology of the different hemodynamic lesions. This information should provide for a more rational approach to aortic valve replacement, at least in terms of early risk/benefit deliberations.

Adult↗
PubMed1985

Operative risk of mitral valve replacement: discriminant analysis of 1329 procedures.

The influence of 34 variables on the operative mortality rate for isolated mitral valve replacement (MVR) was assessed by univariate and multivariate logistic regression analysis. The physiologic lesions were classified as stenosis (20%, operative mortality rate 8 +/- 1%), regurgitation (44%, operative mortality rate 13 +/- 2%), and mixed (34%, operative mortality rate 8 +/- 1%). Functional class (NYHA), previous myocardial infarction, and hepatic dysfunction were powerful independent clinical determinants of operative mortality (p less than .001), along with age at operation and emergency operation (p = .001, p = .04). Concomitant coronary artery bypass grafting or tricuspid annuloplasty, angina, ischemic etiology, and physiologic lesion were not significant independent determinants of operative risk. Interestingly, year of operation, prosthetic valve dysfunction, and previous cardiac surgery had no important effect on operative mortality. Early operative risk for MVR was related to preoperative cardiac and hepatic function. Prior myocardial infarction substantially increased the risk even if the mitral valve disease was not ischemic in origin. Increased operative mortality rate in the subgroup with mitral regurgitation was related to advanced left ventricular failure and myocardial infarction rather than the etiology of the mitral regurgitation. These clinical factors coupled with more refined measurements of left ventricular systolic pump function (independent of loading conditions) should permit more intelligent decision making regarding the optimal timing of MVR, at least in terms of early operative risk.

Adult↗
PubMed1985

Surgical treatment of constrictive pericarditis: analysis of outcome and diagnostic error.

The records of 81 patients with a diagnosis of constrictive pericarditis who underwent surgical treatment were examined to assess the effectiveness of diagnosis and therapy. A false-positive diagnosis occurred in 10 patients (12%); seven had restrictive cardiomyopathy. Of 51 variables examined, only a low right ventricular end-diastolic pressure (RVEDP) significantly and independently predicted diagnostic error. Seventy-one patients with constrictive pericarditis underwent pericardiectomy. Mean follow-up was 4.7 years (maximum 12), and only two patients were untraceable. The study population was notable: 42 patients had visceral as well as parietal pericardial involvement; 32 had idiopathic disease and 25 had pericarditis related to radiation therapy. Results were favorable in 83% of the population. There were seven in-hospital deaths (10%). Actuarial survival estimates were 74% and 64% at 5 and 10 years, respectively. Compared with a normal population, the survival rate of patients with postradiation constrictive pericarditis was significantly inferior, whereas the survival rate of the remaining patients was not significantly different. Patients with constrictive pericarditis and restrictive cardiomyopathy did no better than those with restrictive cardiomyopathy alone. Additionally, patients in NYHA functional class IV had a significantly worse prognosis. Multivariate analysis of 38 preoperative variables identified high RVEDP as a significant independent predictor of in-hospital death, and renal dysfunction and diuretic use were significant independent predictors of overall poor outcome. Differentiation between the diagnosis of constrictive pericarditis and restrictive cardiomyopathy remains a problem. Radiation therapy, pericarditis with restrictive cardiomyopathy, high RVEDP, NYHA class IV status, renal dysfunction, and diuretic use adversely influenced outcome in patients undergoing pericardiectomy.

Actuarial Analysis↗
PubMed1985

Ten year durability and performance of porcine bioprostheses.

The results presented herein describe the prognosis over the first 10 postoperative years for patients operated upon at Stanford University Medical Center who received a first generation, commercially-manufactured porcine bioprosthetic valve. Extrapolation of these results to 15 and 20 years cannot be justified at this time. Conversely, newer tissue valves are believed to be superior, in terms of both hemodynamic performance and long-term durability. Indeed, the newer pericardial valves (Hancock Laboratories and American-Edwards Laboratories) have hemodynamic characteristics that do not differ markedly from those of the tilting disk and bi-leaflet mechanical valves. This promise of potential superior durability in terms of resistance to fibrocalcification will only be able to be determined after patients with these second and third generation tissue valves have been followed for 10 to 15 years postoperatively. Speculation regarding the comparative performance between a durable mechanical valve and a bioprosthesis in the 10 to 15 year time frame is also probably not prudent at this time. We continue to submit, however, that the balance between lower cumulative complication and death rates and finite durability--which currently favors the tissue valve at 10 years--will continue to predominate beyond ten years. This is due for the most part to the constant rate of serious (and frequently fatal) valve-related complications which occur in patients with mechanical valves over the years; having 20 to 40% of patients with mechanical valves succumb within 10 to 15 years due to the complications of TE, ACH, and valve thrombosis is not acceptable, in our opinion, as the magnitude of the risk associated with porcine valve PTF and resultant REOP is lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Mixed olfactory neuroblastoma and carcinoma. A report of two cases.

Two cases of olfactory neuroblastoma mixed with other neoplastic elements are reported. One tumor contained foci of adenocarcinoma and of ganglioneuroblastoma in addition to an undifferentiated small cell component consistent with neuroblastoma; the other tumor histologically resembled small cell undifferentiated carcinoma with foci of squamous differentiation, but was shown by electron microscopy to be neuroblastoma. The histogenesis and treatment of mixed tumors of this type are discussed.

Adenocarcinoma↗
PubMed1984

Calcification of aortic versus mitral porcine bioprosthetic heart valves: a radiographic study comparing amounts of calcific deposits in valves explanted from the same patient.

Calcium detected by radiography was compared in 10 pairs of aortic and mitral glutaraldehyde-treated porcine bioprosthetic heart valves explanted from 10 patients (7 men and 3 women), aged 19 to 68 years (mean 43). Both valves of 6 pairs of valves had undergone primary tissue failure (revealed by cardiac catheterization and angiography) and 1 valve of the other 4 pairs of valves had undergone primary tissue failure. These porcine valves had been implanted from 2 1/4 to 9 years (mean 5 3/4). All 20 explanted valves contained calcium. The grade of calcium was the same in 4 pairs of valves (grade 2+ or 3+), and 1 grade different in 4 pairs of valves (grade 1+ to 4+), with the greater calcium evenly divided between the 2 valve positions. There was more than 1 grade greater mitral valve calcium in 2 pairs of valves (grade 3+ and 4+ mitral vs 1+ and 2+ aortic, respectively). Thus, calcium is usually present in both aortic and mitral valve positions when bioprosthetic valves of this type in either valve position fail as a result of primary tissue failure, and radiographic calcium in porcine bioprosthetic valves is usually similar in grade in both the aortic and mitral valve positions.

Adult↗
PubMed1984

Surgical implications of low cardiac output syndrome after myocardial infarction.

There is a spectrum of conditions that can occur after severe myocardial infarction which cause inadequate cardiac output. Severe and generalized infarction may result in inadequate perfusion of sufficient myocardium to maintain the cardiac work load. Management is limited to supportive measures, including the use of the intraaortic balloon pump. More localized defects of myocardial blood supply can give rise to myocardial rupture. These ruptures may occur in the free wall, within the septum, or within a papillary muscle. Conservative therapy is only indicated as long as improvement continues. Surgical measures should not be delayed in the face of clinical deterioration. They consist of debridement of dead tissue and repair of the defect (or mitral valve replacement if papillary muscle rupture is present).

Cardiac Output, Low↗
PubMed1984

Aneurysmal degeneration of Blalock-Taussig shunts: identification and surgical treatment options.

Many Blalock-Taussig shunts (subclavian to pulmonary artery anastomoses) have been created and a significant number are still being done. Two cases of aneurysmal degeneration of a Blalock-Taussig shunt and their management are described. Development of this rare complication may be related to large shunt flow and long duration. Large, symptomatic or enlarging aneurysms should be repaired and smaller ones studied by serial computed axial tomography. A simple and safe approach to correct this lesion is division and oversewing of the proximal subclavian artery through an anterior approach, assuming adequate pulmonary blood flow is already present or can be established concomitantly.

Adult↗
PubMed1984

The diuretic properties of dopamine in patients after open-heart operation.

Dopamine and dobutamine were administered to 12 patients who had undergone open cardiac operations. To eliminate the effects of variation in systemic blood flow upon renal function the drug infusion rates were adjusted to achieve equal cardiac outputs. Under conditions of equivalent systemic pressure and flow, dopamine (5.0 +/- 1 micrograms X kg-1 X min-1) and dobutamine (3.5 +/- 1.8 micrograms X kg-1 X min-1) had similar effects upon glomerular filtration rate (90 +/- 29 vs. 83 +/- 27 ml X min-1 X 1.73 m-2) and effective renal plasma flow (375 +/- 119 vs. 357 +/- 126 ml X min-1 X 1.73 m-2). However, dopamine administration resulted in a significantly greater diuresis (2.8 +/- 2.7 vs. 1.0 +/- 0.3 ml/min), natriuresis (0.32 +/- 0.39 vs. 0.07 +/- 0.10 mEq Na+/min), and kaliuresis (0.15 +/- 0.06 vs. 0.10 +/- 0.03 mEq K+/min) (P less than 0.05). In patients with modest depression of cardiac performance and renal vasoconstriction, dopamine's selective renal vasodilator effects were not evident. Furthermore, these data suggest that dopamine inhibits tubular solute reabsorption directly. Thus, the diuresis and natriuresis that frequently accompany dopamine administration may occur independently of any effects of dopamine upon renal blood flow.

Adult↗
PubMed1984

Nature of the renal injury following total renal ischemia in man.

The effects of total renal ischemia (TRI) of 15-87 min duration due to suprarenal clamping of the aorta were studied in 15 mannitol-treated patients undergoing abdominal aortic surgery. 15 patients undergoing similar surgery but requiring only infrarenal clamping served as controls. 1-2 h following TRI, GFR was reduced to only 39% of that in controls, 23 +/- 5 vs. 59 +/- 7 ml/min (P less than 0.001). This could not be ascribed to impaired renal plasma flow (RPF), which was mildly reduced to 331 +/- 71 and was not different from the value in controls, 407 +/- 66 ml/min. However, impaired PAH extraction (43 +/- 7%) and isosthenuria, not present in controls, suggest a primary role for tubular injury in lowering GFR at this time. 24 h following TRI, the GFR remained depressed below controls, 45 +/- 8 vs. 84 +/- 8 ml/min (P less than 0.005), while the transglomerular sieving of neutral dextrans was significantly enhanced (radius interval, 24-40 A). A theoretical analysis of transcapillary solute exchange revealed that these findings could be largely explained by a selective reduction of either RPF (-61%) or of transmembrane hydraulic pressure difference (-18%) below control values. Alternately, a combination of these two factors with changes of smaller magnitude could explain the findings. In contrast, a selective increase in oncotic pressure or decrease of the glomerular ultrafiltration coefficient could be excluded as a cause of hypofiltration 24 h after TRI. These observations lead us to suggest that the transient azotemia observed following TRI is due to a self-limited injury to the nephron that is identical to that seen in overt and sustained forms of acute renal failure.

Aged↗
PubMed1984

Meningeal gliomatosis with "negative" CSF cytology: the value of GFAP staining.

We report a patient with meningeal gliomatosis who had signs of meningitis, hypoglycorrhachia, and an intracranial mass. Despite suspicion of a primary intracranial neoplasm, repeated CSF cytologies were not diagnostic and led to a brain biopsy for diagnosis. Immunoperoxidase staining for glial fibrillary acidic protein stained CSF cells that had been thought inflammatory on routine cytology. This case and other reports demonstrate that multiple cytologic examinations may be negative despite extensive gliomatous infiltration of the meninges. Immunoperoxidase staining is useful in cases of suspected meningeal spread of glioma when suspicious cells are seen on routine CSF cytology.

Adult↗
PubMed1984

Prosthetic valve endocarditis caused by Legionella pneumophila.

Prosthetic valve endocarditis due to Legionella pneumophila occurred in a woman who had aortic and mitral valve replacements with porcine xenografts. During surgery for persistent fever and aortic regurgitation due to presumed endocarditis, she had vegetations involving both the aortic and mitral valve prostheses with a circumferential abscess of the aortic annulus. Cultures, Dieterle stain, and direct fluorescent antibody stain of valve tissue, and subsequent measurements of serum antibody levels confirmed L. pneumophila as the infecting organism. This infection occurred in the absence of pneumonia. Legionella pneumophila must be considered a potential cause of culture-negative prosthetic valve endocarditis and should be sought in appropriate clinical circumstances.

Aortic Valve↗
PubMed1984

Mechanoreceptors in human cruciate ligaments. A histological study.

We obtained human cruciate ligaments at the time of total knee replacement and from autopsy and amputation specimens, and examined histological sections of the ligaments for the presence of mechanoreceptors using the Bodian, Bielschowsky, and Ranvier gold-chloride stains for axons and nerve-endings. The cruciate ligaments obtained at the time of total knee replacement were too distorted by disease processes to be of use. The autopsy and amputation specimens, however, contained fusiform mechanoreceptor structures measuring 200 by seventy-five micrometers, with a single axon exiting from the capsule of the receptor. One to three receptors were found at the surface of each ligament beneath the synovial membrane, and were absent from the joint capsules and menisci. Morphologically the receptors resembled Golgi tendon organs, and it seems likely that they provide proprioceptive information and contribute to reflexes inhibiting injurious movements of the knee. This is the first histological demonstration of mechanoreceptors in human cruciate ligaments.

Aged↗
PubMed1984

Independent determinants of operative mortality for patients with aortic dissections.

A 20 year (1963 to 1982) surgical experience including 175 consecutive patients with aortic dissections was analyzed by logistic discriminant analyses to identify predictors of high operative risk. The patient population had characteristics similar to those in large autopsy series. Sixty-nine percent had type A and 58% had acute dissections. The intimal tear was located in the ascending aorta in 60% of the patients, the descending aorta in 27%, and the transverse arch in 13%. The overall operative mortality rate was 23 +/- 3%. The operative mortality rates were substantially lower between 1977 and 1982: mortality in patients with acute type A dissections, 7 +/- 5%; in those with chronic type A, 11 +/- 7%; in those with acute type B, 13 +/- 12%; and in those with chronic type B, 11 +/- 11%. After preliminary univariate screening, the following factors were determined to be significant independent predictors of operative mortality (in rank order of declining predictive power): type A patients (n = 121), renal dysfunction, tamponade, renal/visceral ischemia, and operative date; type B patients (n = 54), rupture, renal/visceral ischemia, and age; all patients (n = 175), renal dysfunction, renal/visceral ischemia, site of tear (ascending less than descending less than arch), tamponade, operative date, and pulmonary disease. Interestingly, several variables had no important bearing on operative mortality, including type (acute vs chronic) of dissection, age, previous operation, rupture, stroke, paraplegia, Marfan's syndrome, concomitant aortic valve replacement and/or coronary artery bypass grafting, site of tear, and whether or not the tear was resected in type A patients; emergency operation, hypertension, previous cardiac symptoms, paraplegia, site of tear, and resection of tear in type B patients; and, when all patients were considered together, age, sex, cardiac symptoms, prior operation, stroke, paraplegia, acute myocardial infarction, acute aortic regurgitation, Marfan's syndrome, and tear resection. These data allow calculation of any individual patient's operative risk and document that the operative mortality rate today is relatively low for all patients with aortic dissections, irrespective of type or acuity. Earlier surgical referral of patients with acute type A or acute type B dissection before irreversible major end-organ ischemia and/or infarction is probably in part responsible for the substantially improved results since 1977.

Aortic Dissection↗
PubMed1984

Severe superior vena cava syndrome and hydrocephalus after the Mustard procedure: findings and a new surgical approach.

Some degree of obstruction of the superior vena cava is common after the Mustard operation for transposition of the great arteries. This can cause superior vena cava syndrome, which in extreme cases may lead to hydrocephalus in young children. While revision of the intra-atrial baffle can be performed, this procedure is associated with significant morbidity and mortality and may not resolve the problem. We describe an alternative operative approach in a group of patients who had superior vena cava syndrome after the Mustard procedure: anastomosis of the innominate vein to the left atrial appendage. This procedure is not complicated to perform and is safe; symptoms were relieved in all patients.

Acute Disease↗
PubMed1984

Degenerative and atherosclerotic aneurysms of the thoracic aorta. Determinants of early and late surgical outcome.

To identify significant predictors of early and late mortality, multivariate discriminant analyses were applied to the clinical outcome of 175 consecutive patients with thoracic aortic aneurysms operated upon over a 20 year span. Only atherosclerotic and degenerative aneurysms were included; the patients were segregated into two groups according to location of the aneurysm. The ascending aortic aneurysm group consisted of 124 patients, 85% of whom required concomitant aortic valve replacement. There were 51 patients in the descending aortic aneurysm group. Mean follow-up was 4.9 years (maximum of 19 years), with a total of 860 patient-years of follow-up. Multivariate analyses revealed that surgical priority and advanced age were independent determinants of hospital mortality in the ascending group; for the descending group, surgical priority and the presence of congestive heart failure were the strongest predictors of hospital mortality. Late mortality in the ascending group correlated with advanced age. Hypertension and the presence of preoperative congestive heart failure were independent determinants of late mortality in the descending group. Several variables did not have any independent bearing on hospital or late mortality, including etiology and location of the aneurysm, previous myocardial infarction, chronic lung disease, and concomitant aortic valve replacement. High-risk subgroups of patients with thoracic aortic aneurysms can be identified by these variables. Aggressive medical plus surgical management and operation prior to aneurysm rupture is necessary to improve both early and long-term survival rates.

Adult↗
PubMed1984

Dobutamine and dopamine after cardiac surgery: greater augmentation of myocardial blood flow with dobutamine.

Left ventricular hemodynamics, dimensions and coronary sinus blood flows were measured simultaneously after infusions of dobutamine and dopamine. Ten patients were studied 6, 10 to 15, and 24 hr after cardiopulmonary bypass surgery. The dose of each drug was adjusted to increase cardiac output by 25%. Heart rate was held constant with atrial pacing. Dobutamine and dopamine increased peak left ventricular dP/dt from baseline values by 72% vs 58% during the early study, 77% vs 78% in the intermediate study, and 95% vs 79% in the late study (all NS, difference between drugs). Similarly, there were no significant differences in hemodynamic response or in cardiac dimensions after the two drugs in any period. Both drugs increased myocardial oxygen uptake during the intermediate and late studies (32% vs 33% and 34% vs 25%). With dobutamine this increase was matched by a similar increase in coronary blood flow; however, failure of the expected increase in coronary blood flow with dopamine suggested coronary constriction. Although dobutamine and dopamine have similar hemodynamic effects, dobutamine has the advantage of not limiting the increase in coronary blood flow associated with increased oxygen demand.

Catecholamines↗