Biomedical subjects
Publications and source records attributed to A Starr.
We report 2 cases of extensive atherosclerosis of the ascending aorta, arch of the aorta, innominate artery, and bilateral carotid arteries treated surgically at St. Vincent and Veterans Administration Medical Centers of Portland, Oregon.
BACKGROUND: Subclavian angioplasty and resection and end-to-end anastomosis for coarctation repair carry a substantial risk of recurrence of coarctation. The combined technique using both these methods has shown good results but requires a longer period of continuous cross-clamping of the aorta. METHODS: A modified technique using intermittent cross-clamping with a period of reperfusion between cross-clamping periods was used. After the end-to-end anastomosis the clamps are released for 10 minutes and reapplied to do the subclavian angioplasty. Between 1991 and 1996 this was done in 26 infants (mean age, 5 weeks; range, 1 day to 6 months; median, 3 weeks). Mean weight was 3.85 kg (range, 1.5 to 8.4 kg). Mean length of follow-up was 23 months. Twenty-two patients (85%) had associated anomalies, excluding patent ductus arteriosus, and 5 patients (19%) had another procedure performed at the same time. RESULTS: There was no mortality. The mean echocardiographic gradient was 4 mm Hg in the immediate postoperative period and 2.9 mm Hg during follow-up. Residual or recurrent coarctation as detected by significant echocardiography or blood pressure gradient did not develop in any infant. CONCLUSIONS: This modified technique of anastomosis is an effective way of relieving coarctation with excellent intermediate-term results.
We report a case of traumatic tricuspid valve regurgitation and late presentation with transient ischemic attacks caused by the presence of a right-to-left shunt through a small atrial septal defect.
H-reflexes in normals were elicited by percutaneous electrical and magnetic stimulation of proximal nerve roots at the cauda equina. H-M interval to S1 nerve root stimulation at the level of the S1 foramen was 6.8 +/- 0.33 ms, with side to side difference of 0.16 +/- 0.13 ms. Compression/ischemia of the sciatic nerve in the mid-thigh abolished the H-reflex to stimulation of the tibial nerve at the popliteal fossa when the H-reflex to S1 nerve root stimulation was preserved. The length of the S1 nerve root in human cadavers was measured to be 17.5 +/- 03 cm, providing an estimated dorsal root conduction velocity of 67.3 m/s and a ventral root conduction velocity of 54 m/s. We conclude that the H-M interval to S1 root stimulation can provide reliable measures of conduction within the spinal canal including proximal afferents, anterior horn cells and ventral roots.
OBJECTIVE: To define mechanisms accounting for transient deafness in three children (two siblings, ages 3 and 6, and an unrelated child, age 15) when they become febrile. DESIGN: Audiometric tests (pure-tone audiometry, speech and sentence comprehension), tympanometry, middle ear muscle reflex thresholds, otoacoustic emissions (OAEs), and electrophysiological methods (auditory brain stem responses [ABRs], sensory evoked potentials, peripheral nerve conduction velocities) were used to test the children when they were afebrile and febrile. RESULTS: ABRs, when afebrile, were abnormal with a profound delay of the IV-V and absence of waves I-III. The ABR in one of the children, tested when febrile, showed no ABR components. Measures of cochlear receptor function using OAEs were normal in both febrile and afebrile states. Cochlear microphonic potentials were present in the three children, and a summating potential was likely present in two. When afebrile, there was a mild threshold elevation for all frequencies in the 15-yr-old and a mild elevation of thresholds for just low frequencies in the two siblings. Speech comprehension in quiet was normal but impaired in noise. One of the siblings tested when febrile had a profound elevation (>80 dB) of pure-tone thresholds and speech comprehension was absent. Acoustic reflexes subserving middle ear muscles and olivocochlear bundle were absent when febrile and when afebrile. No other peripheral or cranial nerve abnormalities were found in any of the children. Sensory nerve action potentials from median nerve in one of the children showed no abnormalities on warming of the hand to 39 degrees C. CONCLUSION: These children have an auditory neuropathy manifested by a disorder of auditory nerve function in the presence of normal cochlear outer hair cell functions. They develop a conduction block of the auditory nerves when their core body temperature rises due, most likely, to a demyelinating disorder of the auditory nerve. The auditory neuropathy in the two affected siblings is likely to be inherited as a recessive disorder.
OBJECTIVES: Auditory neuropathy is a recently described disorder in which patients demonstrate hearing loss for pure tones, impaired word discrimination out of proportion to pure tone loss, absent or abnormal auditory brainstem responses, and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We have identified eight pediatric patients having hearing deficits that are most likely due to a neuropathy of the eighth nerve. In this study, the results of audiologic testing performed with these eight children are described. STUDY DESIGN: Retrospective review of audiologic findings in eight children with auditory neuropathy. METHODS: Each subject was tested with pure tone and speech audiologic testing, auditory brainstem response, and click-evoked otoacoustic emissions. Results of these tests were tabulated and summarized. RESULTS: Pure tone audiologic testing revealed five children with upsloping sensorineural hearing loss, two with high frequency loss, and one with a mild, flat configuration. Six children demonstrated poor word discrimination scores, and the other two had fair to good word discrimination. All eight subjects had normal distortion product and transient otoacoustic emissions. All eight children demonstrated absent or marked abnormalities of brainstem auditory evoked potentials. These findings suggest that while cochlear outer hair cell function is normal, the lesion is located at the eighth nerve. CONCLUSIONS: Recent advances in otoacoustic emissions testing permit differentiation of neural deafness from sensory deafness. This paper describes the clinical presentation and audiologic findings in pediatric auditory neuropathy, as well as the recommended management of these patients. Otolaryngologists should be aware of this disorder and implications for its management, which differs from treatment of sensorineural hearing loss.
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BACKGROUND: The cumulative incidence of a postoperative event is the percentage of patients who experience the event by postoperative time T. Its complete determination requires all patients to be followed until T. In ongoing series, the Kaplan-Meier method is employed because not all patients have been observed until T. When applied to nonfatal events, however, the Kaplan-Meier estimates probabilities as if the patients who die before they sustain an event continue to be at risk thereafter. It thus estimates risk in the unrealistic situation where death does not occur. METHODS AND RESULTS: Cumulative incidence can be estimated directly, to provide the probability of actually experiencing an event before death, that is, when death properly eliminates patients from further risk of the event. We compare cumulative incidence and Kaplan-Meier estimates in two series of mitral valve replacement patients: thromboembolism in a completed series of ball valves implanted in relatively young patients and valve explant in an ongoing series of porcine valves in older patients. Kaplan-Meier estimated a higher event percentage than the cumulative incidence, and the difference was greater in the older patients, who had a higher death rate. CONCLUSIONS: Cumulative incidence, unlike Kaplan-Meier, provides estimates of the percentage of patients who will actually sustain an event. Cumulative incidence is more meaningful for individual patient counseling and more useful for estimating resource utilization in a managed population.
OBJECTIVE: To test the hypothesis that use of aprotinin at hall dose would be more cost-effective or as efficacious as full-dose aprotinin or no aprotinin during open heart surgery. DESIGN: Cost-effective analysis, unmasked prospective comparison. SETTING: Community hospital. PATIENTS: One hundred thirty-three patients undergoing open heart surgery. INTERVENTIONS: Patients in 3 consecutive groups undergoing open heart surgery were allocated to receive no aprotinin, full-dose aprotinin, or half-dose aprotinin. MAIN OUTCOME MEASURES: Total cost (in dollars) of blood products administered plus cost of aprotinin at various dosages, comparison of total blood products administered during hospitalization, and closure time required in the operating room. RESULTS: Full-dose and half-dose aprotinin significantly (P < .05) reduced the total blood products administered during hospitalization and the operating room closure time. However, use of half-dose aprotinin resulted in a significant cost savings (P < .05) when compared with either the cost of blood products required in the nodose aprotinin group or the cost of blood products plus aprotinin in the full-dose aprotinin group. CONCLUSION: Use of aprotinin at half dose in a community hospital resulted in a significant reduction in costs, blood product use, and operating room closure time in patients undergoing open heart surgery.
We describe a valve reconstruction technique for congenital bicuspid aortic valve stenosis employing a commissurotomy, resection of raphe between conjoint leaflets, and bileaflet augmentation-resuspension using a triangular strip of glutaraldehyde-preserved autologous pericardium. This maneuver relieves aortic valve stenosis, preserves the native valve leaflets, reproduces the natural trileaflet scalloping of the aortic valve annulus, and improves cusp coaptation.
BACKGROUND: Elevated blood glucose levels in the postoperative period are associated with an increased risk of deep wound infection in diabetic individuals undergoing open heart operations at Providence St. Vincent Hospital. METHODS: Of 8,910 patients who underwent cardiac operations between 1987 and 1993, 1,585 (18%) were diabetic. The rate of deep sternal wound infections in diabetic patients was 1.7%, versus 0.4% for nondiabetics. Nine hundred ninety patients had their operation before implementation of the protocol and 595 after implementation. Charts of all diabetic patients were reviewed. Mean blood glucose levels were calculated from documented results of finger-stick glucometer testing. RESULTS: Thirty-three diabetic patients suffered 35 deep wound infections: 27 sternal (1.7%) and eight at the donor site (0.5%). Infected diabetic patients had a higher mean blood glucose level through the first 2 postoperative days than noninfected patients (208 +/- 7.1 versus 190 +/- 0.8 mg/dL; p < 0.003) and had a greater body mass index (31.5 +/- 1.4 versus 28.6 +/- 0.1 kg/m2; p < 0.05). Multivariable logistic regression showed that mean blood glucose level for the first 2 days (p = 0.002), obesity (p < 0.002), and use of the internal mammary artery (p < 0.02) were all independent predictors of deep wound infection. Institution of a protocol of postoperative continuous intravenous insulin to maintain blood glucose level less than 200 mg/dL was begun in September 1991. This protocol resulted in a decrease in blood glucose levels for the first 2 postoperative days and a concomitant decrease in the proportion of patients with deep wound infections, from 2.4% (24/990) to 1.5% (9/595) (p < 0.02). CONCLUSIONS: The incidence of deep wound infection in diabetic patients was reduced after implementation of a protocol to maintain mean blood glucose level less than 200 mg/dL in the immediate postoperative period.
We report the successful repair of pulmonary incompetence in an adult due to the congenital absence of the posterior leaflet of the pulmonary valve. The repair consisted of bicuspidization of the pulmonary valve, which achieved competence and eliminated the symptoms and echocardiographic manifestations of right ventricular overload while preserving the native valve.
Brain potentials evoked to non-targets in an auditory target detection task changed in amplitude, duration, polarity, and scalp topography as a function of position in the stimulus sequence relative to the target. (1) A negative prestimulus readiness like-potential, or RP, the poststimulus N100, and a late slow wave to non-targets immediately after the target were reduced in amplitude compared to non-targets immediately before the target. The amplitudes of these potentials after the target then increased in size as a linear function of the number of non-targets in the sequence. (2) The amplitudes of the positive components, P50 and P200, were larger to non-targets immediately after the target than to non-targets immediately before the targets. P50 amplitude then decreased to subsequent non-targets in the sequence in a linear manner; P200 amplitude was reduced equivalently to all subsequent non-targets. (3) The duration of the P200 component could extend into the time domain when the P300 to targets would occur. The P200 component to non-targets was therefore designated 'P200/300'. The duration of the P200/300 component was shorter to non-targets immediately after the target than to non-targets immediately before the targets. P200/300 duration then extended in a linear manner to subsequent non-targets in the sequence and approached the peak latency of the P300 evoked by targets. (4) The anterior/posterior scalp distribution of P50 and the polarity of the late slow wave to non-targets changed as a function of non-target position in the sequence. The subject's response to the targets (button press or mental count) influenced these sequential effects. Linear trends for sequence were present in the press but not the count conditions for the amplitude of the RP, N100, and P300; linear trends for P50, P200/300 duration, and the late slow wave were found in both the press and count conditions. Reaction time was speeded as a function of the number of preceding targets. These dynamic changes in the processing of auditory signals were attributed to an interaction of attention and the subjective expectancies for both the appearance of a target stimulus and the requirement to make a motor response.
OBJECTIVE: Valve repair for aortic insufficiency may provide an alternative to aortic valve replacement in selected patients. This repair could be an attempt at permanent correction or palliation to allow the aortic annulus to grow and avoid the use of anticoagulation. Based upon a five-year experience, we proposed a classification according to valvular anatomy which could be a guide to patient and procedure selection. METHODS: Between September 1989 and February 1995, 44 consecutive patients underwent aortic valvuloplasty for aortic incompetence at our institution. Patients' ages ranged from 19 months to 76 years with a mean of 33 years. The etiology of aortic incompetence was congenital in 30 patients, degenerative in 7 patients, rheumatic in 5 patients, and infective endocarditis in 2. Aortic valve lesions were classified into three different types: type I, aortic annular dilation (8 patients); type II, excessive aortic leaflet tissue (12 patients); and type III, restricted leaflet motion with or without deficient leaflet tissue (24 patients). Type I needed commissural plication in 7 patients; and aortic annuloplasty, which was simple in 6 patients, and pericardial-augmented in 2. Type II necessitated midleaflet excision in 11 patients and leaflet plication in 7. Type III required leaflet extension in 19 patients, leaflet replacement in 1 patient, aortic valve commissurotomy in 13 patients augmentation commissurorrhaphy in 2, leaflet shaving in 4, and repair of leaflet perforation in 2. RESULTS: Postoperative echocardiography revealed a significant decrease in the degree of aortic incompetence. Mean follow-up was 2.6 +/- 1.4 years. There was no mortality. Patients improved as is evident by NYHA functional class postoperatively. Eight of the first 13 patients (18%) needed reoperation. Three of these reoperations were bail-out procedures, and 3 patients (7%) who underwent the leaflet extension technique were reoperated upon 19 months to 3 years later. Presently, 23 patients are without anticoagulation, 11 take aspirin and 2 receive coumadin for combined mitral procedures. CONCLUSIONS: Aortic valve repair provides a low risk option with satisfactory intermediate-term results for the treatment of aortic insufficiency in appropriately selected patients. Patient and procedure selection may be based upon the echocardiographic anatomy of the aortic valve, and a comparative risk benefit appraisal with valve replacement.
INTRODUCTION: The objective of this study was to describe facial myokymia in experimental animals accompanying kainic acid affects on facial motor neurons. MATERIAL & METHODS: Anesthetized cats were injected with kainic acid into the pons adjacent to the facial nucleus. Facial movements appeared shortly after the injections and facial electromyographic potentials were recorded. Cats were killed up to 4 weeks later, the brainstems were processed histologically, and the number of neurons in the facial nucleus counted. RESULTS: Cats receiving injection of kainic acid adjacent to facial nucleus all developed spontaneous writhing movements of the face ipsilateral to the injection site, clinically resembling facial myokymia in humans. Transient facial paresis, lasting several weeks, appeared in some of the cats. Facial myokymia occurred independent of histological evidence of neuronal loss in facial nucleus, whereas facial paresis occurred in all but one of the animals with significant neuronal loss in the facial nucleus. Placing a needle into the superior olive without injecting kainic acid or injections of kainic acid into cochlear nucleus was not accompanied by facial myokymia or subsequent facial paresis. CONCLUSION: Facial movements in cats similar to myokymia in humans accompanies kainic acid injections adjacent to the nucleus of the facial nerve.
Prosthetic valve endocarditis (PVE) emerged approximately 37 years ago when the first human heart valve replacements were performed. PVE can be classified as 'early' or 'late' with the pathophysiology and etiologic organisms varying between the two subgroups. The incidence of PVE ranges up to 0.5% per patient-year for mechanical mitral valves and up to 1.0% per patient-year for other valves. The clinical presentation is similar to that of native valve endocarditis, with fever being the most prevalent sign. Diagnosis is based on a constellation of clinical signs and symptoms as well as echocardiographic evaluation of the valve and perivalvular tissues. An algorithm is set forth for diagnosis and management of patients with suspected PVE based on our personal experience and the published literature. Indications for surgery, the surgical approach and methods of PVE prophylaxis and prevention are discussed.
We tested the hypothesis that magnetic stimulation of muscle evokes cerebral potentials by causing a muscle contraction that then activates muscle receptors. We measured cerebral evoked potentials accompanying magnetic stimulation of muscle in 3 patients during surgery both before and after muscle paralysis with succinylcholine, a depolarizing agent. The magnetic stimulation was at low intensity (30%) and at a 2/s rate. The administration of succinylcholine sufficient to produce muscle paralysis did not alter cerebral potentials evoked by either low-intensity magnetic stimulation of muscle (gastrocnemius/soleus) or electrical stimulation of peripheral nerve (tibial nerve). In 1 normal subject, the S1 nerve root action potentials conducting at rapid velocity (> 60 m/s) were detected at the S1 foramen with a needle electrode using electrical stimulation of the tibial nerve. However, no S1 nerve root potentials could be identified to magnetic stimulation of muscle that evoked a cerebral potential. We conclude that magnetic stimulation of muscle activates terminal afferents in the muscle to provide the afferent drive for the cerebral potentials independent of muscle contraction. The failure to detect the afferent volley in S1 nerve root to magnetic stimulation suggests that only a few afferents are activated or that the activation of afferents is temporally dispersed.
We describe a method for performing the distal anastomosis in replacement of the ascending and the proximal arch of the aorta with specific attention to obtaining accurate length and orientation of the graft. This method reduces the incidence of both anastomotic dehiscence due to tension and obstruction caused by redundant graft.