Twenty-five year experience with Starr-Edwards heart valves: follow-up methods and results

A prospective data registry and follow-up service has been in use for cardiac surgery patients at the St Vincent Hospital Heart Institute, Portland, Oregon, since 1960. It presently contains information on more than 4,000 heart valve operations. The physical system has evolved from a manually updated binder of flowsheets to an integrated multicomputer database. The caged-ball valves used as the predominant replacement device have themselves performed successfully, permitting a remarkable 25-year review. The conclusions from a current review of the valves, which have just entered their third decade of use, remain the same as the conclusions from an earlier review of the same series, performed 10 years ago when the valves had just entered their second decade of use.

Tissue and mechanical valves: mutually advantageous interplay

This report is concerned with the dynamic interplay between glutaraldehyde preserved tissue valves (bioprostheses) and mechanical valves. These two classes of valve replacement devices are not competitive, but provide some nonoverlapping characteristic advantages and disadvantages. By proper selection, it may be possible to tailor the kind of device used for a particular patient, thus improving the overall results of bioprosthetic and mechanical valve replacement. Careful selection of patients according to age and the safety of anticoagulation should achieve a series of patients with mechanical and bioprosthetic valves that would be superior to a series in which all patients received a single device. Thus, these devices should be viewed as complimentary rather than competitive since the value of properly matching a prosthesis to the patient will be reflected in improved overall results with each class of prosthesis.

Brain potentials during mental distance judgments

Visual event-related potentials were recorded from a group of 10 normal subjects while they judged the proximity of two letters of the alphabet. Subjects viewed singly the letters A, D, G, L, N, T, W and Z and indicated by button press whether the letter displayed occurred before or after the comparison letter M. Reaction times to close letters (L and N) were longer than ordinally more distant letters (A, D, G, T, W, Z). A late parietally positive potential of approximately 475 ms covaried in latency and amplitude with these judgments. Late potentials were delayed in latency and reduced in amplitude to close letter (L and N) judgments compared to the other letters. The results suggest that mental processes, such as alphabetic distance judgments, may be usefully studied by examining their associated event-related potentials.

Repair of traumatic aortic transection: a management protocol and review of twenty-one patients

Between 1970 and 1987, 21 patients at St. Vincent Hospital and Medical Center underwent surgery for repair of a transected descending aorta. Nineteen of the transections were a result of trauma secondary to motor vehicle accidents, 1 was secondary to compression injury of the chest, and 1 was the result of a fall. All of the patients had diagnostic chest X-rays and all but one X-ray showed a widened mediastinum. Aortography was carried out in 20 cases. Atrio-femoral bypass was used for all but 2 patients, who had femoro-femoral bypass. The mean cross-clamp time was 53 minutes. Interposition graft was used in 16 patients, an intraluminal graft in 1 patient, and primary repair was performed in 2 patients. Survival was 71%, with 4 of the 21 patients expiring in the operating room (2 before the repair could be undertaken), one patient expiring during a laparotomy 2 days after the aortic repair, and one patient expiring 4 days after the repair. Fifteen patients were discharged alive. Survival and patient care could be improved by careful diagnostic assessment and by following a protocol agreed upon by a team of surgeons.

Enhancement of motor cortical excitability in humans by non-invasive electrical stimulation appears prior to voluntary movement

The time course of facilitation of motor evoked potentials (MEPs) to transcranial electrical stimulation delivered at varying intervals near the onset of a voluntary ballistic movement was studied in 4 normal subjects. MEPs were recorded from the left thenar muscles to unifocal anodal stimulation of the right scalp overlying the hand motor area delivered every 8-10 sec. A click, occasionally associated with the scalp stimulation (P = 0.3-0.6), was the signal for the subject to make a brief thumb press on a piston at short latency. The timing of the scalp stimulus and the click was adjusted so that the former occurred approximately between 100 msec before and 100 msec after the onset of the voluntary movement signaled by the EMG in the thenar muscles. MEPs were not detected when the scalp was stimulated 80 msec or more before onset of voluntary movement and then appeared with increasing probability as the time interval before movement shortened. The amplitudes of MEPs in the 80-40 msec period preceding movement onset were small (less than 20% of maximum) and achieved maximum values 20 msec after movement onset.

Late results of ascending aorta-descending aorta bypass grafts for recurrent coarctation of aorta

Ten patients between the ages of 10 and 17 years underwent ascending aorta-descending aorta bypass grafts for recurrent coarctation at the Oregon Health Sciences University from 1975 to 1984. The combined approach through a left thoracotomy and median sternotomy was used in all the patients. This operation was used when the segment of recoarctation was long, dense adhesions were present, collaterals were inadequate, or when a cardiac operation was necessary for an associated lesion. All the patients survived the operation, and the long-term results to date have been satisfactory.

Heart transplantation for cardiac amyloidosis: successful one-year outcome despite recurrence of the disease

Systemic amyloidosis has been considered a theoretical contraindication for heart transplantation because of the concern that amyloidosis is a systemic disease that could potentially recur in the allograft. To date, no patients have been reported to have undergone heart transplantation. One year ago a patient with amyloidosis had a transplantation at the Oregon Health Sciences University, Portland. Results of kidney, rectal, and bone marrow biopsies were normal; however, endomyocardial and gingival biopsies showed positive results for amyloidosis. Recurrence of amyloidosis was detected by electron microscopy 14 weeks after transplantation; however, light microscopy has not shown any amyloidosis at 1 year. No other organ involvement has been documented. The patient is New York Heart Association functional class I, with normal resting hemodynamic parameters 1 year after transplantation. Amyloid heart disease does not necessarily portend a poor early outcome.

Aortic valve replacement with the Starr-Edwards prosthesis: a comparison of the first and second decades of follow-up

There are few prostheses in current use that allow 20-year follow-up. This report compares the rates of valve-related complications during the first and second decades following aortic valve replacement with the Silastic ball prosthesis. (table; see text) Valve-related complication rates with this prosthesis have been low overall. Performance characteristics of this valve have remained stable through the second decade of follow-up. These results should be used as the standard in the evaluation of long-term results with other more recently introduced mechanical and tissue valves.

Aortico-left ventricular tunnel: a clinical review and new surgical classification

This is a collective review of aortico-left ventricular tunnel (ALVT) in the English-language literature. We include the long-term follow-up of a previously reported patient, and a report on 2 new patients. To date, 37 cases of ALVT have been reported. Controversies regarding the definition, etiology, local anatomy, and treatment are discussed. The ages of the patients ranged from 1 day to 25 years old, and the male to female ratio was 2:1. There were associated anomalies in 27% of the patients, and moderate to severe heart failure in 59% of them. Mortality was 100% in the medically managed group; the surgical mortality was 16%. Previous surgical techniques utilized were simple closure, patch closure of the aortic end, and obliteration of the tunnel on both ends. Progressive aortic incompetence seems to be a common, but not well-documented problem on long-term follow-up. We have classified the lesion into four types (I, II, III, and IV) that have a bearing on the appropriate surgical techniques of repair, and describe a new technique for the repair of type III ALVT in which septal aneurysm is present.

Serial echocardiographic findings early after heart transplantation: evidence for reversible right ventricular dysfunction and myocardial edema

Serial M-mode and two-dimensional echocardiograms were performed on 10 patients at 1 week, 1 month, and 3 months after heart transplantation to determine early structural and functional changes in the allograft. Standard M-mode echocardiographic measurements of at least five cardiac cycles were averaged. Right ventricular size and function were assessed by mid-ventricular diameter and the right ventricular apex to lateral tricuspid anulus shortening fraction, respectively, on the two-dimensional apical four-chamber view. There were no consistent differences in left ventricular end-diastolic dimension or fractional shortening between study periods. Left ventricular posterior wall thickness decreased from 15 +/- 2 to 11 +/- 1 mm (p = 0.001), and septal thickness decreased from 15 +/- 2 to 12 +/- 2 mm (p = 0.0006) between the 1-week and 3-month studies. Right ventricular cross-sectional dimension increased from 34 +/- 6 to 39 +/- 6 mm (p = 0.047), and right ventricular fractional shortening increased from 13% +/- 3% to 21% +/- 5% (p = 0.0051) between the 1-week and 3-month studies. There were no correlations between any of the above changes and rejection episodes. There was a weak correlation (r = 0.53) between ischemic time and change in posterior wall thickness. Right ventricular dysfunction and increased left ventricular wall thickness presumably caused by interstitial edema appear to be normal findings early after heart transplantation.

Temporal relationship between single unit activity in superior olivary complex and scalp-derived auditory brainstem response in guinea pig

Single unit activities in the region of the superior olivary complex were recorded from 8 guinea pigs concurrently with the recording of auditory brainstem potentials from the scalp. At any one anatomical site, be it a fiber tract (e.g. trapezoid body) or a nucleus (e.g. medial nucleus of the trapezoid body), the modal latency of the onset discharge of the units encountered corresponded in time with the latencies of several different waves (waves P2-P5) of the auditory brainstem response (ABR). Moreover, at the time of occurrence of just one of the ABR waves, single units in several diverse anatomical sites in and around the superior olive were found with modal latencies of onset discharge at that same time period. The slopes of the latency/intensity functions for both the peaks of the ABR and the modal latency of the onset discharge for most of the single units studied in the superior olive and its adjacent fiber tracts were remarkably similar. These data support the hypothesis of multiple rather than single generator site(s) for components of the ABR, at least, for waves P2-P5 in the guinea pig. These data do not distinguish whether the ABR are generated in part by travelling nerve action potentials or graded synaptic events.

Disordered auditory short-term memory in man and event-related potentials

Four patients with conduction aphasia and impaired auditory but relatively preserved visual digit spans were tested in a task of short-term memory, a digit probe identification task, in both the visual and auditory modalities. Five age-matched normal subjects served as controls. Behavioural measures of response accuracy and reaction time and scalp derived event-related potentials were determined as a function of the number of items to be remembered. These measures were also recorded in a task requiring the detection of infrequent stimuli ('oddball' paradigm). The patients' performance and event-related potential wave forms for the 'oddball' task were no different from those of the controls. In the digit probe identification tasks the patients showed a reduction in amplitude of a positive component at a latency of approximately 450 ms (P450) of the event-related potential to correctly identified probes in the auditory modality. This component was within normal limits with visual testing. There was an inordinate increase in the patients' reaction time to auditory but not visual stimuli when the number of items to be remembered increased from one to three. Event-related potentials were also analysed as a function of speed of reaction time, position of the matching item in the stimulus presentation set and whether the probe was correctly identified as being in-set or out-of-set. Event-related potentials associated with fast reaction times in the auditory task when a single item was presented were no different between patients and controls, indicating that patients were capable of both performing normally and generating normal potentials on some trials. The data suggest that the deficit in auditory short-term memory in these patients occurs during stimulus classification.

Selectivity of attenuation (i.e., gating) of somatosensory potentials during voluntary movement in humans

Attenuation of somatosensory evoked potentials (SEPS) recorded from the scalp during voluntary movement occurs for specific combinations of the finger moved and the peripheral nerve stimulated. The cerebral potential component occurring at a latency of 27 msec (P27) evoked either by stimulation of median nerve at the wrist or by stimulation of 1st and 2nd digit nerves in the fingers were selectively attenuated during movement of 1st digit but were not altered during movement of 5th digit. By contrast, the cerebral P27 component evoked by stimulation of ulnar nerve at the wrist or by stimulation of 5th digital nerve were attenuated during movement of that digit but were not altered during movement of 1st digit. Gating of somatosensory activity is a selective phenomenon occurring when movement involves the areas being stimulated.

Localization, timing and specificity of gating of somatosensory evoked potentials during active movement in man

Short latency somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded at different times simultaneously and after an order to move the ipsilateral thumb (0, 100, 200, 300, 400 and 780 ms). Brain potentials were derived from surface electrodes over the scalp at contralateral postcentral and precentral sites and muscle potentials were derived from surface electrodes over the thenar eminence. Ipsilateral thumb movement did not affect the early lemniscal P14 or the postcentral cortical N20 but was accompanied by attenuation of the cortical postcentral P27 and cortical precentral P22, N30 and P45. These results suggest that the gating induced by voluntary movement in man occurs at thalamocortical level and that the differential effect on postcentral N20 and precentral P22 may represent the activity of different generators. Gating of SEPs during voluntary movement begins approximately 80-100 ms before EMG onset, is maximal at the time the EMG is maximal, and returns to control values after the EMG is concluded. These results suggest that the gating that precedes the onset of EMG activity is related to premotor events in the cerebral cortex and not to centripetal influences. Gating of SEPs to median nerve stimulation was localized to movements of areas innervated by the median nerve, that is, the ipsilateral thumb, index or middle finger, but not to movements of ipsilateral little finger or contralateral thumb.

A tri-institutional comparison of tissue and mechanical values using a patient-oriented definition of "treatment failure"

Selection of valve type for predominant usage is obscured by limiting the analysis to prosthesis-related rather than patient-oriented failure modes. In this report, "treatment failure" is defined as a valve-related death or permanent patient disability; successful reoperations are excluded, and emboli with permanent residua are included. Results with the Starr-Edwards Silastic ball valve (Oregon) and the Hancock (Stanford) and Carpentier-Edwards (Vancouver) porcine valves are compared using this new definition of treatment failure. Evaluated according to structural failure, the mechanical valve is superior to the tissue valve, and using the Stanford definition of valve failure, it becomes so between 5 and 10 years. Using treatment failure, tissue valves are superior at 5 years; at 10 years in the aortic position, the results are comparable; and in the mitral position at 8 to 10 years, tissue valves show a continued but small advantage.

Electrophysiologic studies in selective dorsal rhizotomy for spasticity in children with cerebral palsy

A group of 20 children with spastic cerebral palsy underwent selective dorsal rhizotomy for alleviation of spasticity. Pre- and postoperatively, cortical somatosensory evoked responses (cSSEP), H reflex and F wave studies were done. Clinically there was dramatic reduction of tone without noticeable sensory loss. The electrophysiologic studies showed several findings: (1) many children have abnormal cSSEP preoperatively; (2) surgery seldom leads to a loss of cSSEP; (3) in many patients, there is a noteworthy improvement in the cSSEP wave form; (4) some children have electrophysiologic evidence of spinal cord dysfunction preoperatively and (5) Hmax/Mmax ratio decreases after surgery confirming decrease in tone.

Aortic valve replacement for acute Takayasu's disease

A patient with aortic insufficiency secondary to Takayasu's disease who was treated by aortic valve replacement during active aortic inflammation is described. The patient remains well 29 months postoperatively with minor additional treatment. A review of aortic insufficiency in Takayasu's disease is presented.

Attenuation of auditory-evoked potentials during voluntary movement in man

Long-latency auditory evoked potential (AEP) amplitudes were reduced during voluntary thumb movement. The cerebral component N100 did not change during the movement. By contrast, the cerebral potential P200 and N100-P200 amplitudes were attenuated during the motor task compared to control. This report cannot clearly distinguish if the attenuation obtained in the AEP during the performance of the movement is related to motor events in the cerebral cortex causing 'gating' or to other factors such as habituation or vigilance changes.

A current appraisal of the Waterston shunt

Recent reports have suggested that the classical Blalock-Taussig shunt and its prosthetic modification have a low patency rate in neonates. This prompted a review of 58 neonates undergoing a Waterston shunt for cyanotic congenital heart disease. The 4 mm anastomosis was constructed using a calibrated clamp. There were 20 (35%) hospital deaths, of which 3 were directly related to shunt failure. Operative mortality was associated with increasing complexity of the cardiac lesion, emergency operation, weight less than 3 kg and age less than 48 hours. There were 5 late deaths resulting in an actuarial survival of 52% at ten years. There was one case of late occlusion corresponding to a patency of 92% at 2 years. Anastomotic kinking with preferential flow to one lung occurred in 2 (7%) of 28 patients undergoing repeat angiography at 3 and 5 years respectively. Nineteen patients underwent corrective surgery a mean of 27 months after shunt construction. Six (32%) required an angioplastic repair of the pulmonary artery. Six (16%) of the 38 operative survivors required diuretic therapy for excessive pulmonary flow. The high patency ensures that the Waterston shunt continues to play an important role in the management of low weight neonates who require an emergency systemic-pulmonary shunt. The use of a calibrated clamp reduces the incidence of excessive pulmonary flow. Early corrective surgery and shunt dismantling may reduce the necessity for angioplastic repair.

Ten year survival after coronary artery bypass surgery for angina in patients aged 65 years and older

We have assessed the long-term results of coronary bypass surgery for angina from 1974 to 1983 in 1304 patients aged 65 years and older (group 1). Using actuarial techniques, we determined that the 5 year and 10 year survival rates for patients 65 years old or older were 81 +/- 2% and 65 +/- 3% (mean +/- SE), respectively. The patients aged 65 years and older were further subdivided into those aged 65 to 74 years (group 1a) and 75 to 84 years (group 1b) and were compared with 1700 patients aged 55 to 64 years (group 2). The operative mortality in the three subgroups was 3%, 3%, and 2%, respectively (p = NS). For coronary bypass surgery, the duration of hospital stay was significantly longer (p less than .0001) by a mean of 1 to 2 days for group 1 patients and the cost of hospitalization was higher by a mean of $ 700 (p = .25). The cost of hospitalization was significantly higher only for group 1b patients (p = .005). The 5 year survival rates for the three subgroups (1a, 1b, and 2) were 83 +/- 2%, 73 +/- 5%, and 91 +/- 1%, respectively, and the 10 year survival rates were 66 +/- 3%, 65 +/- 7% (7 year rate for subgroup 1b), and 77 +/- 2%, respectively. The lower survival rates for subgroups 1a and 1b were significant (p less than .001); however, this lower survival was only seen in men.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral cortical contributions to sensory evoked potentials: hydranencephaly

The contribution of the cerebral cortex to the generation of sensory evoked potentials was studied in an infant with hydranencephaly. On CT scan no tissue above the thalamus was noted. Long-latency potentials to auditory stimuli were absent whereas the short-latency or brain-stem auditory evoked potentials and some of the components of the middle latency auditory evoked potentials (No and Po) were present. To visual stimulation only the electroretinogram was detected. To somatosensory stimulation only the spinal cord potentials could be detected. The absence of long-latency components in each of the sensory modalities supports the concept that these potentials require intact cerebral hemispheres in man.

The thoracic surgical industrial complex

The thoracic surgical industrial complex is an industry worth $2 billion per year and is shaped by six dominant forces, three positive and three negative. The three positive forces are technological innovation, entrepreneurial activity, and the flow of capital and the three opposing forces, government regulation, cost-containment, and the excessive costs of product liability insurance. We are now at a critical time in the evolution of this industry, with growth being enhanced in areas of lesser risk, namely, nonimplantable devices, at the expense of high-risk implantable devices. The future of the artificial heart hinges on the balance between the six forces, and this analysis examines the possibilities for timely development of this ultimate implantable device.

Ten-year survival following aortic valve replacement: A multivariate analysis of coronary bypass as a risk factor

The additional risk of coronary bypass surgery was analysed in 664 patients over 40 years of age undergoing aortic valve replacement between 1969 and 1981. Four hundred sixty-seven patients underwent aortic valve replacement alone, while 197 patients with coronary artery disease underwent combined aortic valve replacement and coronary bypass surgery. There were no significant differences in the preoperative hemodynamic characteristics of the two groups of patients. There were 41 (9%) operative deaths following aortic valve replacement alone and 20 (10%) following aortic valve replacement with coronary bypass surgery. Since 1976, operative mortality has fallen to 5% and perioperative myocardial infarction to 2% following the combined procedure. Ten-year actuarial survival (standard error) was 56 (3%) following aortic valve replacement and 49 (6%) following aortic valve replacement and coronary bypass surgery. A multivariate analysis including both groups of patients revealed that age, functional class and year of operation significantly affected ten-year survival (p less than 0.05). The same analysis showed that coronary artery disease requiring coronary bypass surgery also decreased ten year survival in patients undergoing aortic valve replacement (p = 0.06).

Late right ventricular reconstruction following valvotomy in pulmonary atresia with intact ventricular septum

Experience over two decades in the surgical management of pulmonary atresia with intact ventricular septum demonstrates that eventual right ventricular (RV) reconstruction is possible in the majority of patients surviving valvotomy in infancy. Ten of 17 operative survivors of early valvotomy have eventually received a patch graft to the RV outflow tract, with no reoperative deaths (mean follow-up, 7.4 years). RV systolic pressures, suprasystemic prior to reoperation, are near normal after outflow patch reconstruction. Serial cineangiograms show evidence of RV growth by measurement of tricuspid annulus diameter (TAD), and demonstrate a rate of growth [d(TAD)/d(body length)] greater than a normal rate derived from autopsy data. The mean TAD growth rate is significantly greater than that of patients with less favorable ventricle types treated with a systemic-pulmonary shunt alone. Measurement of TAD is a useful method for following RV growth, and may aid in selecting patients for RV reconstruction.

Late ball variance with the Model 1000 Starr-Edwards aortic valve prosthesis. Risk analysis and strategy of operative management

The first generation of aortic ball-valve prostheses, used until 1965, was associated with poppet damage owing to fatty infiltration of the silicone rubber ball, a phenomenon termed ball variance. For the Model 1000 Starr-Edwards valves, almost all cases were discovered before 8 years. However, a review of our patients still at risk with the original valve and poppet, prompted by other recent reports of late ball variance, has shown that severe variance can exist up to 20 years after implantation. There is a relationship between the year of valve implantation and the timing and severity of ball variance for the overall series of patients surviving operation, but for the subgroup currently at risk the sample sizes are too small to detect any difference, if one still exists. Only three of 12 patients in the current subset were found to have severe variance. Simple ball change has been the operation of choice. Prophylactic reoperation is not indicated in the current subset, but patients require careful follow-up and should be considered for reoperation should symptoms develop.

Effect of initial reperfusion temperature on myocardial preservation

The effect of initial postischemic reperfusion temperature on myocardial preservation was studied in the isolated working rat heart model. After baseline measurement of aortic flow rate, coronary flow rate, and heart rate, 40 hearts were subjected to 60 minutes of ischemic arrest at 15 degrees C induced with a single dose of cold potassium cardioplegic solution. Hearts were then revived with a 10 minute period of nonworking reperfusion at 28 degrees, 31 degrees, 34 degrees, or 37 degrees C (10 hearts each), followed by 5 minutes of nonworking reperfusion at normothermia, followed by 30 minutes of working perfusion. Repeat measurements of function were obtained and postischemic release of creatine kinase into coronary effluent was determined. Recovery of aortic flow was significantly reduced at lower initial reperfusion temperatures (75% at 28 degrees C versus 88% at 37 degrees C) and the effect was approximately linear throughout the range studied (p less than 0.05). Release of creatine kinase into coronary effluent was greater at lower initial reperfusion temperatures (421 ImU/min/gm wet weight at 28 degrees C versus 115 ImU/min/gm wet weight at 37 degrees C), also in a linear manner (p less than 0.05). In this model, initial postischemic hypothermic reperfusion is deleterious to cellular integrity and functional recovery of the preserved myocardium. Studies in higher animals and humans are warranted to further evaluate the effect of initial reperfusion temperature on myocardial preservation.

The entrapped balloon: report of a possibly serious complication

Entrapment of a balloon in the femoral artery at the site of insertion is described. A rupture in the balloon allowed the formation of a clot inside the balloon, which necessitated surgical removal.

Severe mitral regurgitation in a woman with a double orifice mitral valve

A 64 year old woman with partial atrioventricular canal and double orifice mitral valve presented with severe mitral regurgitation secondary to a torn leaflet. The double orifice regurgitant mitral valve is an unusual finding at operation.

Stimulus frequency and masking as determinants of P300 latency in event-related potentials from auditory stimuli

The effects of target tone frequency, presence of a masking stimulus, and subject sex on the auditory ERP were studied with an 'oddball' paradigm. P300 latency became shorter (about 15 msec) as the difference between the standard (1000 Hz) and target tone frequency increased (1500, 2000, 4000 Hz) but became longer (about 10 msec) with the presence of a white noise masking stimulus. Similar results were obtained for both the P3a and P3b subcomponents of the P300 potential. No significant differences between the adult male and female subjects were observed. The role of stimulus parameters in applied testing situations is discussed.

'Gating' of somatosensory evoked potentials begins before the onset of voluntary movement in man

The inflow of somatosensory information to the cerebral cortex is modified before and during active movement in animals. This phenomenon has been termed 'gating' and occurs at several levels of the sensory pathway. We studied somatosensory evoked potentials (SEPs) to stimulation of the median nerve at the wrist during voluntary movement of the ipsilateral thumb in man. Results indicate that SEPs are attenuated shortly after a command to move (approximately 100 ms before the onset of the electromyogram (EMG)), become maximally attenuated with maximum EMG and return to normal size when movement is finished.

Effects of age on the P300 component of the event-related potential from auditory stimuli: peak definition, variation, and measurement

An auditory "oddball" paradigm was used to elicit the P300 component of the event-related brain potential (ERP) from a large sample of young (5 to 15 years) and older (20 to 86 years) persons. Distinct P3a and P3b subcomponents of the P300 were observed within individuals and across trial blocks. Age affected P300 latency in a similar fashion for both subcomponents with latency increasing about 65 msec between 20 and 70 years. P300 latency variability also was found to increase somewhat with advanced age. These results confirmed previous age-related ERP changes and extended them to the P3a and P3b subcomponents.

The Starr-Edwards valve

This report reviews the results obtained with the current models of the Silastic ball valve, classifying the experience with the mitral and aortic models into the periods (formula: see text) before and after 1973. Valve failure is defined according to the Stanford method and includes any valve-related death or complication necessitating valve removal (there have been no mechanical failures). Comparison of the valve model used today with the same model used in the late 1960s shows that the results have improved dramatically, especially with regard to thromboembolism. The results obtained with valves implanted after 1973 compare favorably with those of other contemporary valves introduced in the early 1970s.

Cognitive evoked potentials (P300) in early Huntington's disease

The P3 component of both auditory-event- and visual-event-related potentials of 13 patients with Huntington's disease was studied and compared with the P3 component of normal patients. The latencies of the patients' P3 components were compared with the latency-age regression lines generated by the normal population in both modalities. A P3 latency was considered abnormal if it fell above the 2-SE limit for the latency-age regression line. The incidence of normal or abnormal P3 latencies in the two modalities was compared with the results of computed tomography, electroencephalography, and neuropsychological testing. Nine patients had abnormal P3 latencies and ten patients had abnormal visual P3 latencies, with seven having abnormal latencies on both tests and 12 having abnormal latencies on one of the two tests. An abnormal P3 latency in one modality did not imply an abnormal P3 latency in the other. An abnormality of the P3 latency did not correlate with an abnormality in results from computed tomography, electroencephalography, or neuropsychological testing.

Mitral replacement: clinical experience with a ball-valve prosthesis. Twenty-five years later

The purpose of this report is to review the results of mitral valve replacement since a first report in the Annals of Surgery in 1961, in order to determine the relative importance of new valve designs versus other surgical variables. The continued use of the silastic ball valve in its 1966 configuration (Model 6120), by providing a comparative data base for other new prosthetic valves, allows this analysis. For a valid comparison with the tilting disc (Bjork-Shiley) and the porcine (Hancock and Carpentier-Edwards) valves, only results with the silastic ball valves implanted during comparable time frames should be used. (Formula: see text) Thus, there are no significant differences in the results obtained with the silastic ball valve in time frames comparable to other contemporary valves introduced in the early 1970s. Improved results, therefore, must be non-prosthetic valve related.

Intracranial potentials correlated with an event-related potential, P300, in the cat

Intracranial recordings of long-latency, event-related potentials were obtained from paralyzed, artificially respirated cats. A modified oddball paradigm was employed in which cats were presented with a randomized series of two tones, a 'frequent' 4 kHz stimulus and a 'rare' 1 kHz stimulus. A tail shock was administered 700 ms after onset of the rare tone. Under these circumstances the stimulus elicited a positive component at the vertex similar to the human P300. Intracranial potentials associated with the rare tone usually manifested components of greater amplitude than did potentials associated with the frequent tone. A positive component occurring in latency between 200 and 350 ms only accompanied the presentation of the rare stimulus. The P300 component, which was positive at the dura, appeared as a negative component within a few millimeters of the surface over a wide area of the marginal and suprasylvian gyri. Changing the probability of the rare stimulus resulted in a reduction in the amplitudes of both the intracranial negative component and the P300 recorded at the skull. Components of large amplitude associated with the rare stimulus were obtained from the region of the hippocampus. These components reversed polarity, sometimes more than once, as the electrode was advanced. Substantial latency differences were often observed between the P300 recorded at the skull and P300-like intracranial components associated with the rare stimulus. These results suggest that the cortices of the marginal and suprasylvian gyri and the hippocampal region contribute to the generation of the cat P300.

Vibration and muscle contraction affect somatosensory evoked potentials

We recorded potentials evoked by specific somatosensory stimuli over peripheral nerve, spinal cord, and cerebral cortex. Vibration attenuated spinal and cerebral potentials evoked by mixed nerve and muscle spindle stimulation; in one subject that was tested, there was no effect on cutaneous input. Presynaptic inhibition of Ia input in the spinal cord and muscle spindle receptor occupancy are probably the responsible mechanisms. In contrast, muscle contraction attenuated cerebral potentials to both cutaneous and muscle spindle afferent volleys; central mechanisms modulating neurons in the dorsal columns nuclei, thalamus, or cerebral cortex are probably responsible.

Auditory brain stem potentials recorded at different scalp locations in neonates and adults

The auditory evoked brain stem potential was recorded in 14 normal full-term infants and nine normal-hearing adults. Silver-silver chloride electrodes were placed at nasion, forehead, vertex, each mastoid over the bony prominence, and the seventh cervical vertebra (noncephalic reference) in order to study the scalp distribution of the auditory brain stem response. Large differences in the scalp distribution between the newborn and adult populations were observed. At the ipsilateral mastoid, an x wave occurring at approximately 2 ms and a y wave occurring at approximately 3.3 ms were identified in the adult; this contrasts to a y wave at approximately 3.7 ms in the neonate. It appears that there are either separate generators for some of the components in the adult versus the neonate, and/or as the nervous system matures, myelinization occurs with a concomitant change in the scalp distribution of the auditory brain stem potentials.

Valvotomy for pulmonary atresia with intact ventricular septum. A disciplined approach to achieve a functioning right ventricle

During the past 20 years, a consistent policy in applying early valvotomy has resulted in a unique opportunity to appraise the long-term results of this approach in pulmonary atresia with intact ventricular septum. Since 1964, 27 of 35 patients with pulmonary atresia with intact ventricular septum had type 1 or 2 right ventricle, 25 of these had early valvotomy, seven with and 18 without concomitant shunt. The remaining two patients with type 2 right ventricle and the eight patients with type 3 right ventricle received a shunt alone. Overall operative mortality was 34%; for those patients weighing more than 3 kg and those operated upon since 1977, it was 18% and 16%, respectively. There were 17 survivors of early valvotomy: 11 had valvotomy alone and six had valvotomy with shunt; 12 had type 1 right ventricle and five had type 2 right ventricle. Survival rates (+/- standard error) for these 17 patients were 85% +/- 10% and 68% +/- 17% at 5 and 10 years, respectively. The probability of reoperation was 100% by 6 years of age; outflow patch reconstruction was employed in all patients in whom reoperation has been performed. Aggressive follow-up and early recatheterization were essential features of management. Delayed reconstruction after shunt alone was unsuccessful in three patients. Primary valvotomy without shunt is the operation of choice for patients with pulmonary atresia with intact ventricular septum and type 1 right ventricle. Concomitant shunt may be required for some patients with type 1 and most with type 2 right ventricle, selected preoperatively by angiography or after valvotomy by clinical necessity. Delayed right ventricular reconstruction after shunt alone is not an acceptable approach when an outflow tract is present.

About the origin of cerebral somatosensory potentials evoked by Achilles tendon taps in humans

This study examines the effects of ischemic hypoxia and cooling of the leg, muscle contraction and vibration on cerebral potentials evoked by Achilles tendon taps and posterior tibial nerve stimulation to obtain indirect evidence leading to the identification of receptors activated by tendon taps. Experiments performed during ischemia of the leg showed that these receptors lie between the ankle and the knee. Cooling of the leg showed that they are located deep in muscles or bone. Experiments performed during vibration and muscle contraction suggest that muscle stretch receptors provide the afferent input responsible for Achilles tendon tap evoked potentials. All of these experiments point to primary muscle spindles in the proximal gastrocnemius-soleus muscle belly as the main source of afferent input for evoking cerebral potentials to Achilles tendon taps in humans.

Emergency coronary artery bypass surgery after intracoronary thrombolysis for evolving myocardial infarction

Sixteen patients underwent emergency coronary artery bypass surgery immediately after intracoronary streptokinase infusion for acute evolving myocardial infarction. Of these, 11 patients had 70% residual stenosis in the recanalised vessel, and in five thrombolysis was unsuccessful. There were no hospital deaths. All the patients sustained myocardial necrosis, the peak activity of creatine phosphokinase correlating with the time to reperfusion. Chest tube drainage (mean 960 ml) was significantly higher than for control patients but did not correlate with the total dosage of streptokinase. No patients had further myocardial infarction or developed recurrent angina. Selected patients may benefit from coronary bypass surgery after intracoronary streptokinase infusion. If necessary this may be performed immediately with low mortality and morbidity.

Cerebral somatosensory potentials evoked by muscle stretch, cutaneous taps and electrical stimulation of peripheral nerves in the lower limbs in man

Somatosensory cerebral evoked potentials were recorded in man to natural forms of somatosensory stimulation of the lower extremity including stretching of the muscle tendons, tapping on muscle bellies and tapping on cutaneous surfaces. These potentials were compared with those evoked by electrical stimulation of peripheral nerves measuring the amplitudes and latencies of the evoked potential components and defining the effects of stimulus variables on these parameters. Spinal cord potentials could only be detected to electrical stimuli. Mechanical stimulation of tendons and muscle bellies evoked scalp potentials at latencies earlier than those evoked by electrical stimulation of the peripheral nerve and by cutaneous stimulation at the same level of the leg. Muscle receptors, most probably muscle spindles, are the source of the short latency components obtained by the stretching of tendons and tapping on muscle bellies. The proximal location of these receptors as well as very rapid spinal conduction account for the latency difference. The potentials were larger to electrical stimulation of nerve trunks than to mechanical stimulation of tendons or skin, suggesting the asynchronous activation of a smaller number of fibres by the latter. Individuals with the largest potentials to one form of stimulation usually had the largest potentials to the other modes of stimulation. The use of physiological stimuli such as muscle stretch to test the transmission in specific neural pathways might be useful in investigating the processing of relatively selective afferent volleys using noninvasive evoked potential recordings.

Influence of age at operation on late results with subclavian flap aortoplasty

Despite the popularity of subclavian flap aortoplasty for repair of aortic coarctation, reported experience and follow-up in neonates is surprisingly limited. This paucity of reports prompted this review of age-related late recurrence rates. Of 83 patients having subclavian flap aortoplasty from 1976 to 1983, 60 were less than 8 weeks of age at operation (mean 2.6 weeks). Operative and late mortality were 18% and 14%, respectively. After a mean follow-up of 26 months, 10 patients have experienced recurrent coarctation (a mean of 10 months elapsed between operations). For 23 patients older than 8 weeks of age at operation (mean 20 months), operative and late mortality were 13% and 10%, mean follow-up is 16 months, and no patient has yet experienced recurrence. Thus, 75% of infants less than 8 weeks of age at operation are free of recoarctation at 2 years, and 100% of older children are free of recoarctation at 2 years (p = 0.06). Review of the literature corroborates our findings. The difference in recurrence rates may be due to age-dependent involution of residual coarctation tissue unavoidably left in place during subclavian flap aortoplasty. We conclude that subclavian flap aortoplasty is effective for correction of coarctation in infants, but patients less than 8 weeks old have a significant risk of early recurrence. Based on this review and our recently reviewed experience with end-to-end anastomosis, our preference is to use the latter in this age group when technically feasible.

Late results of combined mitral valve replacement and coronary bypass surgery

The incremental risk of coronary bypass surgery was analyzed in 718 patients undergoing mitral valve replacement between 1971 and 1983. Ninety-eight patients (14%) had significant coronary artery disease requiring coronary bypass surgery. In 70 of these patients, the origin of the mitral valve disease was nonischemic, whereas 28 patients had ischemic mitral regurgitation unsuitable for conservative valve surgery. There were six operative deaths (9%) and four perioperative myocardial infarctions (6%) after mitral valve replacement and coronary bypass surgery for nonischemic mitral valve disease. Operative mortality was related to low output cardiac failure before operation or perioperative myocardial infarction. Actuarial curves predict survival (+/- standard error) of 55 +/- 7% at 5 years and 43 +/- 8% at 10 years. Preoperative functional class was the only significant predictor of long-term survival in this group (p less than 0.05). The actuarial survival of the 620 patients without coronary artery disease who underwent mitral valve replacement alone was 63 +/- 3% at 10 years. This was significantly better than that of the 70 patients who underwent mitral valve replacement and coronary bypass surgery for nonischemic mitral valve disease (p less than 0.001). Conversely, 5 year survival of the 28 patients with ischemic mitral regurgitation was 43 +/- 10%. This confirms the negative detrimental effect of an ischemic origin of mitral valve disease on survival after mitral valve replacement and coronary bypass surgery (p less than 0.0001).

Coarctation of the aorta in patients younger than three months. A critique of the subclavian flap operation

Unexpected and disappointing late results with the subclavian flap operation prompted this analysis of repair of coarctation in infants under 3 months of age. A total of 134 such patients underwent surgical repair since 1960 with 55 end-to-end anastomoses performed earlier in our experience (mean follow-up 5.0 years) and 67 subclavian flap angioplasty operations performed more recently (mean follow-up 2.0 years). The operative mortality was not significantly different (p = 0.3) between end-to-end anastomosis (29%) and subclavian flap angioplasty (19%), but it was significantly higher (p less than 0.01) in the first week of life (56%). Recurrent coarctation occurred in 16 cases, necessitating reoperation. The reoperation-free rates (with standard error) at 5 years for end-to-end anastomosis and subclavian flap angioplasty were 92% +/- 5% and 75% +/- 7%, respectively (p = 0.01). Eight of 10 patients who had reoperation after angioplasty had early recurrence with continued involution of the periductal tissues and growth of the posterior aortic ridge. Six patients who had recurrence after anastomosis demonstrated late anastomotic growth failure. The most common reoperation technique was patch aortoplasty (10 patients). The high incidence of early recurrence with subclavian flap angioplasty in infants under 3 months of age suggests end-to-end anastomosis as the procedure of choice when applicable.

Late surgical results for ischemic mitral regurgitation. Role of wall motion score and severity of regurgitation

The indication for concomitant valve operations for ischemic mitral regurgitation is examined in 120 consecutive patients with regurgitation who had coronary bypass. Ischemic mitral regurgitation was mild in 56%, moderate in 18%, and severe in 27%. Compared with patients without mitral regurgitation who underwent coronary bypass, significantly more patients with regurgitation had cardiomegaly (31% versus 5%), left heart failure (42% versus 6%), and abnormal wall motion scores (71% versus 42%). Eighty-three patients (69%) with ischemic mitral regurgitation had coronary bypass alone and 37 (31%) also had a valve operation. All patients with mild ischemic mitral regurgitation were treated by coronary bypass alone, as compared to 67% with moderate and 6% with severe regurgitation. Operative mortalities for mild, moderate, and severe ischemic mitral regurgitation were 4%, 10%, and 38%, respectively; 5 year survival rates were 82%, 60%, and 48%, respectively. Other significant determinants of survival were wall motion score, shock, cardiomegaly, left heart failure, and acute and multiple myocardial infarctions. Patients with mild ischemic mitral regurgitation and a low wall motion score (n = 40) had a 5 year survival rate of 94%. For patients with either moderate/severe regurgitation (n = 27) or a high wall motion score (n = 25), but not both, the 5 year survival rate was 70%. In 20 patients with both a high wall motion score and moderate/severe regurgitation, it was 33%. An additive detrimental effect is apparent. The change from mild to moderate/severe ischemic mitral regurgitation was equivalent to an increase of about 8 wall motion score units in terms of effect on survival. Ischemic mitral regurgitation is a powerful additive risk factor to wall motion score in coronary bypass. Mild regurgitation is best managed by coronary bypass alone. If regurgitation is moderate, it may still be possible to avoid a valve operation and have acceptable results. Severe ischemic mitral regurgitation usually necessitates coronary bypass and a mitral valve operation.

Thrombotic and embolic complications with silastic ball prosthetic valves

Eighteen years of continuous clinical use with the Starr-Edwards ball-valve prosthesis provides an extensive data base for comparison with more recently introduced cardiac prostheses, and establishes the credentials of this valve for current clinical use. Since 1965, 558 aortic (model 1260) and 285 mitral (model 6120) ball-valve prostheses have been inserted at the University of Oregon. Thromboembolic rates for the entire series (1965-1983) and our more recent experience (1973-1983) were 3.8% per year and 2.8% per year for the aortic valve; and 5.1% per year and 2.6% per year for the mitral valve. Patients who had experienced one embolic episode were substantially more likely to experience a subsequent event. Thrombotic stenosis was seen at rates of 0.1% per patient year and 0.4% per patient year for the aortic and mitral valves, respectively. These results are compared with other current series using a variety of mechanical and tissue prostheses. The Starr-Edwards valve remains a durable mechanical cardiac prosthesis with thromboembolic complications similar to most other current prostheses. Thrombotic stenosis tends to be rare, gradual, and electively managed as opposed to the sudden, unpredictable, and catastrophic thrombosis seen with tilting disc valves.