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Biomedical subjects

W Gee

Publications and source records attributed to W Gee.

At least 19 recordsLinked to original sources
PubMed2000

Extra-anatomic redo of MIDCAB and OPCAB: an early experience.

BACKGROUND: Eighteen patients with unstable angina underwent repeat myocardial revascularization without cardiopulmonary bypass using saphenous vein grafts from either the left (13) or right (2) axillary arteries or the descending thoracic aorta (3). Patients' ages ranged from 53 to 85 years. Left ventricular ejection fractions ranged from 15% to 60%. METHODS: In 14 patients, the heart was exposed through an anterior thoracotomy, a minimally invasive direct coronary artery bypass (MIDCAB) technique. In 3 patients a left posterolateral thoractomy (lateral MIDCAB) was performed. One patient underwent repeat sternotomy (off-pump coronary artery bypass: OPCAB). In MIDCAB and lateral MIDCAB patients, the "target" vessel was a coronary artery in 8 patients and a previously placed vein graft in the remaining 9 patients. One patient underwent repeat sternotomy, and 3 coronary arteries were bypassed with a complex vein graft attached to the left axillary artery. Two patients died of mesenteric ischemia on the 2nd and 7th postoperative day. The remainder of patients were discharged from the hospital free of angina. Early graft patency was demonstrated by noninvasive vascular laboratory testing and/or angiography in the 13 survivors in whom the axillary artery had been the site of the proximal anastomosis. RESULTS: Follow-up ranged from 1 to 25 months. No other patients have died, and none have undergone additional surgical or catheter-based procedures. Three patients have developed recurrent angina, and in 4 patients the extra-anatomic bypass grafts have apparently become occluded. CONCLUSION: Extra-anatomic, off-pump bypass from the axillary artery or descending thoracic aorta to one or more coronary arteries can be performed safely in seriously ill patients requiring a repeat bypass procedure. The early results, regarding relief of angina, are encouraging.

Aged↗
PubMed1999

Ocular volume change per minute with ocular pneumoplethysmography.

Ocular pneumoplethysmography was performed before and after 1,737 carotid endarterectomies, 82% of which were performed for carotid lesions of hemodynamic consequence. Preoperative ocular hypoperfusion without ischemia was associated with at least transient postoperative ocular hyperemia. A difference in ocular volume change per minute of 14.0%, female greater than male, was explained by sex differences in heart rate, brachial pulse pressure and eye size. These observations may have a direct application in the management of diabetic retinopathy with panretinal photocoagulation.

Blood Pressure↗
PubMed1996

Outcome of severe brain injury: a multimodality neurophysiologic study.

We screened all head-injured trauma patients admitted to Lehigh Valley Hospital during a 2-year period. From 725 screened patients, 69 patients in a coma on the second day after trauma were entered into this study. During the first week, these patients underwent electroencephalography (EEG), evoked potentials, ocular pneumoplethysmography, and transcranial Doppler (TCD) sonography. Clinical examinations were undertaken 2 and 7 days after trauma. Test results were correlated with functional clinical outcome at 6 months. In a multiple regression analysis, EEG was the major independent variable that significantly predicted 6-month outcome based on Glasgow Outcome Scale score. Transcranial Doppler sonography contributed a small additional component. Though EEG was the most significant predictive factor in this neurophysiological battery, it did not add significantly to the predictive power of Glasgow Coma Scale score determined at day 7. These findings suggest that in neurophysiologic testing in this type of patient is not useful in improving predictive outcome data.

Adolescent↗
PubMed1994

Internal carotid artery redundancy is significantly associated with dissection.

BACKGROUND AND PURPOSE: Redundant internal carotid arteries have been considered a risk factor in tonsillectomy, adenoidectomy, and surgical treatment of peritonsillar abscess and also a potentially treatable cause of stroke. However, an association between internal carotid artery redundancy and spontaneous dissection has not yet been clearly demonstrated. METHODS: We reviewed, for spontaneous carotid artery dissection, records of all patients admitted to our institution during the period from 1986 through 1992 with the diagnosis of stroke or transient ischemic attack. We also reviewed 108 percutaneous cerebral arteriograms performed between September 1992 and December 1992 for presence of carotid artery redundancies. RESULTS: Thirteen patients exhibited spontaneous dissection. Of these, 8 of 13 (62%) patients and 13 of 20 (65%) internal carotid arteries, viewed to the siphon, had significant redundancies, kinks, coils, or loops. Of 108 consecutive arteriograms of patients without dissection, in which 187 internal carotid arteries were viewed to the siphon, there were 20 (19%) patients and 22 (12%) of 187 vessels with significant redundancy. Five patients in the dissection group and 2 in the nondissection group had bilateral internal carotid artery redundancy (P = .0019 and P = .0001, respectively). CONCLUSIONS: We found a significant correlation between internal carotid artery redundancy and dissection, particularly if redundancy is present bilaterally.

Adult↗
PubMed1993

Biomechanics of ocular pneumoplethysmography.

A mathematical analysis of ocular pneumoplethysmography is presented, based on the physiological, anatomical, and biomechanical properties of the eye. Ocular pneumoplethysmography is a clinical procedure involving elevation of intraocular pressure, by application of a suction cup to the sclera, to a level that exceeds ophthalmic artery systolic pressure. As decay in intraocular pressure is allowed, return of retinal artery pulsations indicates ophthalmic artery systolic pressure. We obtain a quantitative relationship between increase in intraocular pressure and applied vacuum, and compare the theoretical predictions with experiments on rabbits in which a variable descending vacuum was applied to bilateral scleral eyecups. The bilateral intraocular pressures were simultaneously recorded from cannulae in the respective vitreous bodies, and the pressures at which return of ocular pulsations were observed were correlated with the scleral vacuums. Regression lines were calculated for three serial determinations in each animal, with two groups of animals distinguished by the inner diameter of the eyecups used. The theoretical results indicate that the relationship between intraocular pressure increase and applied vacuum is independent of Young's modulus, and depends primarily on the ratio of the diameter of the vacuum cup to the diameter of the eye.

Animals↗
PubMed1993

Amplitude of the ocular pneumoplethysmography waveform is correlated with cardiac output.

BACKGROUND AND PURPOSE: Ocular pulse amplitude, the amplitude of the ocular pneumoplethysmographic waveform, is altered in several ophthalmologic diseases that disturb ocular blood flow, implying that ocular pulse amplitude may provide an estimate of ocular blood flow. Because ocular blood flow currently cannot be quantified in humans, two experiments were undertaken to evaluate the association of ocular pulse amplitude with total body blood flow. METHODS: In experiment 1, cardiac output was determined by cardiac catheterization in 181 patients who underwent OPG-Gee testing during the same hospitalization. In experiment 2, 110 instances of atrial arrhythmia captured on ocular pneumoplethysmographic tracings were evaluated for transient changes in heart rate (R-R ratio) associated with transient changes in ocular pulse amplitude (ocular pulse amplitude ratio). RESULTS: In experiment 1, average ocular pulse amplitude in the two eyes (OPAAV) was significantly correlated with cardiac output/heart rate (r = 0.53; p < 0.0001) and cardiac index/heart rate (r = 0.43; p < 0.0001). In experiment 2, R-R ratio was significantly correlated with ocular pulse amplitude ratio (r = 0.85; p < 0.001). CONCLUSIONS: These results show that ocular pulse amplitude, a physiological measurement obtained from the globe, is correlated with cardiac output. They imply that ocular pulse amplitude may provide a clinically useful estimate of at least the pulsatile component of ocular blood flow.

Aged↗
PubMed1993

The impact of cardiac index on cerebral hemodynamics.

BACKGROUND AND PURPOSE: Current noninvasive testing allows accurate assessment of cerebrovascular hemodynamics. The cardiovascular influence on the noninvasive assessment of cerebrovascular studies has not been defined. This study was designed to determine the effect of cardiac index (CI) on cerebral blood flow velocities, ocular pulse amplitude, ophthalmic systolic pressure, and ocular blood flow (OBF) as currently estimated by noninvasive laboratories. METHODS: Based on a retrospective study of 181 patients, we prospectively evaluated 45 patients undergoing right heart catheterization for hemodynamic monitoring to correlate the relation between CI, transcranial Doppler sonography, and ocular pneumoplethysmography. Patients with hemodynamic instability, severe carotid stenoses, massive cerebral infarct, or sepsis were ineligible for the study. Simultaneous recordings of systemic blood pressure, ophthalmic systolic pressure, heart rate, ocular pulse amplitude, middle cerebral artery blood flow velocities, and cardiac output were obtained on all patients. OBF was calculated from the heart rate and ocular pulse amplitude. RESULTS: The relation between OBF and CI is expressed by the equation CI = 2.36 + 0.61 x OBF (r = .47, P = .0010). The middle cerebral artery peak systolic velocities and CI had a correlation of .36 (P = .0181). The equation, derived from the linear relation between OBF and CI, was then validated on a sample of 15 patients. With the apparent linear relation between OBF and CI, we used the derived equation to predict CI from OBF. The OBF determination predicted CI within 30% in all patients and within 20% in 53.3% of the patients. CONCLUSIONS: We demonstrated that OBF and middle cerebral artery systolic velocity decrease with diminishing CI. Our findings suggest that CI may be potentially estimated in selected patients by noninvasive assessment of OBF using ocular pneumoplethysmography.

Blood Pressure↗
PubMed1993

The cerebral hyperperfusion syndrome: diagnostic value of ocular pneumoplethysmography.

PURPOSE: There were two purposes to our study. The first was to characterize the ocular hyperperfusion associated with carotid endarterectomy. The second was to relate ocular hyperperfusion to the clinical presentation of cerebral hyperperfusion syndrome. METHODS: This was a retrospective chart review of 2331 patients who underwent carotid endarterectomy at our institution between June 1978 and May 1991. RESULTS: Twelve of these carotid endarterectomies were associated with ocular hyperperfusion on the side of operation. Clinical evidence of cerebral hyperperfusion syndrome was observed in five of these 12 procedures. In these five patients there were two associated fatal intracerebral hemorrhages and one permanent coma. In the latter three patients the contralateral internal carotid arteries were totally occluded. CONCLUSION: Ocular hyperperfusion, as documented with ocular pneumoplethysmography, is useful in alerting the physician to the potential for development of the cerebral hyperperfusion syndrome.

Air↗
PubMed1992

Risk factors for stroke after coronary artery bypass.

To determine the prevalence of stroke after coronary artery bypass grafting and to evaluate risk factors, we reviewed the records of 1000 patients undergoing coronary bypass within a 1-year time period. Demographic and perioperative data were evaluated by chi 2 analysis. A history of diabetes, evidence of mural thrombus, positive oculopneumoplethysmography findings, increased age, aortic calcification, and postoperative arrhythmias all correlated with increased risk of permanent neurologic deficit for the patient undergoing coronary bypass. Risk factors were analyzed with stepwise logistic regression. A history of diabetes, presence of mural thrombi, and aortic calcification carried a higher probability that the patient would have a permanent neurologic deficit.

Aged↗
PubMed1989

Duplex ultrasound and ocular pneumoplethysmography concordance in detecting severe carotid stenosis.

Concordance between two independent tests should serve to increase the accuracy of diagnosis. A combination of ocular pneumoplethysmography and duplex ultrasound, which uses high-resolution B-mode imaging plus spectral analysis, was used to evaluate 289 consecutive patients prior to biplane carotid angiography. Where there was concordance, the noninvasive tests predicted the presence or absence of hemodynamically severe carotid stenosis (75% or greater cross-sectional area reduction) with a sensitivity of 96.8%, a specificity of 95.9%, an accuracy of 96.2%, and positive and negative predictive values of 91.0% and 98.6%, respectively. Of the 538 study arteries, only four (0.74%) angiographically severe lesions escaped detection by both noninvasive tests. Sources of diagnostic error for both tests were defined. We believe that the combination of duplex ultrasound and ocular pneumoplethysmography significantly improves the overall assessment of carotid atherosclerosis.

Carotid Artery Diseases↗
PubMed1989

Abnormal ocular pneumoplethysmographic results in unilateral neovascular glaucoma.

Little is known about the predictive value of ocular pneumoplethysmography in patients with ophthalmic disease. We evaluated eight patients with unilateral increased intraocular pressure due to neovascular glaucoma who did not have evidence of severe extracranial carotid stenosis by duplex scanning and continuous-wave Doppler ultrasound. The ophthalmic systolic pressure measured by ocular pneumoplethysmography was decreased in the affected eye of all eight patients, indicating that neovascular glaucoma may be a cause of abnormal ocular pneumoplethysmographic results. Patients with neovascular glaucoma tended to have larger interocular ophthalmic systolic pressure differences than other patients with false-positive ocular pneumoplethysmographic results by noninvasive criteria.

Aged↗
PubMed1989

Ocular pneumoplethysmography can help in the diagnosis of giant-cell arteritis.

We compared the results of ocular pneumoplethysmography in nine patients who had a temporal artery biopsy (TAB) diagnostic of giant-cell arteritis with results of ocular pneumoplethysmography in nine patients with normal TAB results and 112 patients with anterior ischemic optic neuropathy or central retinal artery occlusion assumed to be nonarteritic. The mean +/- SD ocular pulse amplitude with ocular pneumoplethysmography was 3.9 +/- 1.8 mm in the group with abnormal TAB results and 10.6 +/- 4.0 mm in the group with normal TAB results. Every patient with abnormal TAB results had an average calculated ocular blood flow less than 0.60 mL/min, while only one patient with normal TAB results fell in this range. The average calculated ocular blood flow had a sensitivity of 100% and a specificity of 93.4% in the diagnosis of giant-cell arteritis, with a diagnostic accuracy of 93.9%. These results rival the diagnostic accuracy of the erythrocyte sedimentation rate and TAB results.

Aged↗