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Biomedical subjects

L Wetstein

Publications and source records attributed to L Wetstein.

At least 19 recordsLinked to original sources
PubMed1990

Management of unresectable malignant esophageal obstruction.

Malignant esophageal obstruction (MEO), especially with esophago-respiratory fistula (ERF), requires efforts to achieve a meaningful degree of palliation. Laser vaporization (LV) of the esophageal tumor and placement of an endoesophageal prosthesis (EEP) represents a new combination for palliation of MEO. The purpose of the present study was to evaluate the neodymium-yttrium-aluminum-garnet (Nd:Yag) laser in reopening the esophageal channel to permit both swallowing and insertion of an EEP. Twenty-three consecutive patients with MEO were evaluated, and ERF was documented by preoperative contrast study in eight patients. All 23 patients underwent laser vaporization, dilation, and surgical placement of EEP. Adequate swallowing was attained in 21 patients; one patient with an ERF experienced recurrent aspiration from failure of the EEP to occlude the fistulous tract. Operative morbidity was 17% (4/23), which included: wound infection, 2; persistence of ERF, 1; esophageal perforation, 1; and food impaction, 1. Thirty-day operative mortality was 9% (2/23). Palliation was excellent in 87% (20/23), with discharge from the hospital by the seventh postoperative day. Mean survival was 3.3 months. We conclude that laser vaporization followed by placement of an EEP represents a major advance in the palliation of MEO.

Aged↗
PubMed1988

Effect of transmural versus nontransmural myocardial infarction on inducibility of ventricular arrhythmias during sympathetic stimulation in dogs.

Transmural myocardial infarction interrupts sympathetic nerves and denervates viable muscle distal to myocardial infarction. The effect of sympathetic stimulation on responses to programmed ventricular stimulation was studied in dogs without myocardial infarction (Group I: n = 5), with transmural anterior wall myocardial infarction (Group II: n = 6) and with nontransmural anterior wall myocardial infarction (Group III: n = 9). Ventricular effective refractory period during sympathetic stimulation decreased by 16 +/- 18, 1 +/- 2 and 12 +/- 8 ms (mean +/- SD) in viable muscle of the inferoapical left ventricle in Groups I, II and III, respectively, suggesting efferent sympathetic denervation by transmural myocardial infarction only. Sustained ventricular tachycardia or fibrillation was induced more easily during sympathetic stimulation in six of the six dogs with transmural infarction, but in only two of the nine dogs with nontransmural infarction (p less than 0.01). It is concluded that the partial sympathetic denervation produced by transmural myocardial infarction enhances the ease of induction of ventricular tachycardia and fibrillation during sympathetic stimulation. A similar mechanism may lead to increased risk for lethal arrhythmias during periods of high sympathetic tone in patients with transmural myocardial infarction.

Animals↗
PubMed1988

Unilateral high-frequency jet ventilation during one-lung ventilation for thoracotomy.

One-lung ventilation is indicated during thoracic operations for bronchopleural fistula, pulmonary abscess, and pulmonary hemorrhage in spite of the possibility of the development of severe hypoxemia. To evaluate methods for improving oxygen transport during one-lung ventilation, we applied high-frequency jet ventilation (HFJV) and continuous positive airway pressure (CPAP) to the nondependent lung following deflation to atmospheric pressure in each procedure, and measured the effects on cardiac output and arterial oxygenation. In each case, the dependent lung was ventilated with conventional intermittent positive pressure ventilation (IPPV). Eight patients were studied during posterolateral thoracotomy using double-lumen endobronchial tubes. HFJV or CPAP to the nondependent lung improved arterial oxygenation significantly during both closed and open stages of the surgical procedures (p less than 0.008). When the chest was open, HFJV maintained satisfactory cardiac output, whereas CPAP usually decreased cardiac output (p less than 0.008). There were no significant differences in mean partial pressure of arterial carbon dioxide between HFJV, CPAP, and deflation to atmospheric pressure. In conclusion, HFJV to the nondependent lung provides not only satisfactory oxygenation but also good cardiac output, thereby maintaining better oxygen transport than CPAP or deflation to atmospheric pressure, while the dependent lung is ventilated with IPPV during one-lung ventilation for thoracotomy.

Aged↗
PubMed1988

Effective separation of normal, acutely ischemic, and reperfused myocardium with P-31 MR spectroscopy.

The ability of phosphorus-31 magnetic resonance (MR) spectroscopy to accurately characterize myocardium as normal, ischemic, or reperfused but viable was examined in the canine model of acute coronary artery occlusion. P-31 MR measurements of in vivo myocardial pH, phosphocreatine, adenosine triphosphate, and inorganic phosphate levels were made at baseline and for 6 hours after sustained coronary occlusion (ten animals) or coronary occlusion reperfused after 60 minutes (12 animals). Ten control animals were studied in parallel fashion, without coronary occlusion. Myocardial tissue characterization derived from the P-31 MR spectroscopy data by logistic regression analysis had an overall accuracy of 89%. Overall accuracy was unaffected by duration between coronary occlusion and P-31 MR study. Thus, metabolic data obtained with P-31 MR spectroscopy effectively separate normal, acutely ischemic, and reperfused but viable myocardium.

Adenosine Triphosphate↗
PubMed1987

Technique for implantation of phrenic nerve electrodes.

Permanent ventilatory support is necessary in patients with upper motor neuron respiratory muscle paralysis and central alveolar hypoventilation. Weaning these patients from chronic ventilation is extremely advantageous. Diaphragm pacing accomplishes this goal. In the past implantation of phrenic nerve electrodes has been undesirable either because the procedure is too extensive or because of the high failure rates. This report describes a simple, expeditious, and uniformly successful technique for bilateral phrenic nerve electrode placement.

Diaphragm↗
PubMed1987

Assessment of exercise oxygen consumption as preoperative criterion for lung resection.

Determination of preoperative pulmonary function is crucial in avoiding complications from pulmonary resection. Many have employed static pulmonary function testing in an attempt to decrease morbidity and mortality from lung resections. The purpose of the present study was to correlate preoperative static pulmonary function, one-second forced expiratory volume (FEV1), and exercise O2 consumption (MVO2) with postoperative morbidity and mortality. Fifty consecutive patients underwent preoperative FEV1 and MVO2 determinations. A criterion for surgical resection included an FEV1 greater than 1.7 liters for pneumonectomy, greater than 1.2 liters for lobectomy, and greater than 0.9 liters for wedge resection. The surgeon was blinded as to the results of MVO2 studies. Mean age was 63.8 years (range, 47 to 76 years). There were 10 pneumonectomies, 28 lobectomies, and 12 wedge resections. Among the 50 surgical candidates selected solely on the standard FEV1 values, mortality was 4% (2/50) and morbidity, 12% (6/50). Stratification on the basis of exercise performance showed a 29% mortality (2/7) and a 43% morbidity (3/7) in patients with an MVO2 less than 10 ml/kg/min. Patients with an MVO2 less than 20 but greater than 10 ml/kg/min had a 10.7% morbidity (3/28), and there were no deaths. No patients with an MVO2 greater than 20 ml/kg/min sustained any morbidity or died (p less than 0.001). We conclude that exercise is an important criterion in the preoperative evaluation of patients for pulmonary surgery. An MVO2 less than 10 ml/kg/min is associated with significant morbidity and mortality.

Aged↗
PubMed1987

Intracellular myocardial pH measured in vivo with sustained and reperfused coronary occlusion.

Intracellular pH provides an important measure of the adequacy of local tissue perfusion. The purpose of this study was to measure regional intracellular myocardial pH (impH) in the ischemic zone in vivo during experimental canine coronary occlusion, with and without coronary reperfusion. Twenty adult dogs were studied. Ten dogs underwent permanent ligation of the proximal anterior left descending coronary artery (group L), five dogs had coronary reperfusion after 1 hour of total coronary occlusion (group R), and five dogs did not undergo ligation and served as controls (group C). Intracellular myocardial pH was measured by 31phosphorus nuclear magnetic resonance spectroscopy at baseline and then at 15-minute intervals for 6 hours after coronary occlusion (or after sham occlusion in group C). Baseline impH did not differ among groups (group C, 7.22 +/- 0.12 mean +/- standard error of mean; group L, 7.17 +/- 0.07; group R, 7.22 +/- 0.09). During hour 1 of total occlusion, the impH of both groups L (6.58 +/- 0.05) and R (6.55 +/- 0.08) was significantly reduced as compared with the impH of group C (7.3 +/- 0.12; p less than 0.05). At 0 to 1, 1 to 3, and 3 to 5 hours of reperfusion, the impH of group R (7.34 +/- 0.08, 7.27 +/- 0.07, and 7.29 +/- 0.06, respectively for these times) did not differ from group C (7.26 +/- 0.11, 7.21 +/- 0.07, and 7.25 +/- 0.10). At these same times, the impH of group L (6.47 +/- 0.05, 6.57 +/- 0.04, and 6.75 +/- 0.04) was significantly reduced as compared with both groups R and C (p less than 0.05). Thus a severe, persistent regional intracellular myocardial acidosis occurs in the ischemic zone with coronary occlusion but is rapidly corrected by reperfusion within 1 hour.

Acidosis↗
PubMed1986

Effect of thromboxane synthetase inhibition on vulnerability to ventricular arrhythmia following coronary occlusion.

Release of thromboxane (TXA2) during acute myocardial infarction may be an important contributing factor in the genesis of ventricular fibrillation (VF). We assessed the effect of selective TXA2 inhibition on vulnerability to VF after total occlusion of the anterior descending coronary artery in chloralose-anesthetized cats. Animals were pretreated with vehicle or with CGS-13080, a TXA2 synthetase inhibitor, 3.0 or 9.0 mg/kg intravenously. There was an apparent dose-dependent protective effect following CGS-13080 administration, in which the decrease in VF threshold following coronary occlusion was attenuated. Also, the incidence of spontaneous ventricular arrhythmia in the first 30 minutes after occlusion was reduced by two thirds in the 9.0 mg/kg CGS-13080 group compared to the vehicle-treated animals. This protective effect does not appear to be due to a change in hemodynamics, effective refractory periods, or extent of ischemia. TXA2 released during coronary occlusion appears to be arrhythmogenic, and inhibiting its synthesis may be protective.

Animals↗
PubMed1986

Histopathologic correlates of inducible ventricular tachycardia in two experimental canine models of myocardial infarction.

Ventricular tachyarrhythmias are the leading cause of sudden cardiac death. Determination of the substrates conducive to the initiation of ventricular tachyarrhythmias remains an important clinical goal. The purpose of this study was to correlate electrophysiologic and histopathologic parameters conducive to the initiation of sustained ventricular tachycardia using programmed electrical stimulation in two canine models of myocardial infarction. Histopathologic correlates included: infarct pattern (heterogeneous vs. homogeneous morphology), distribution (viable epicardial or endocardial rim), and size. Twenty-one adult dogs were randomly divided into two groups: (1) 12 dogs underwent two-stage, 2-hour occlusion of the proximal left anterior descending coronary artery (LAD); and (2) nine animals had permanent, complete occlusion of the LAD with latex embolization. Using programmed ventricular pacing with two premature ventricular extrastimuli, initiation of ventricular tachycardia was attempted at both 1 and 2 weeks after infarction with the chest closed and opened each time. Electrophysiologic evaluation of the infarct type correlated significantly with the histologic morphology of the infarction (p less than 0.001), the presence of a viable epicardial rim was an extremely important discriminating variable for ability to induce sustained ventricular tachycardia (p = 0.04). The presence of an endocardial rim was not significant (p = 1.0). Infarct size alone was only marginally related to ventricular tachycardia inducibility (p = 0.08). Non-uniform infarcts were more conducive to the initiation of sustained ventricular tachycardia than homogeneous infarcts (p = 0.025). The presence of a large, non-uniform infarct was the best overall discrimination variable for inducibility (p = 0.0002). Thus, in these experimental models, specific infarct morphologies correlate significantly with susceptibility to inducible sustained ventricular tachyarrhythmias.

Animals↗
PubMed1986

Sensitivity and specificity of lingular segmental biopsies of the lung.

Open lung biopsy is frequently performed as an emergency procedure in patients with undiagnosed bilateral diffuse pulmonary disease. In many situations, this procedure is undertaken in hemodynamically compromised or septic patients. An expeditious and simple technique to make an accurate diagnosis would be extremely advantageous. Biopsy of the lingular segment addresses most of these issues. Lingular biopsies, however, have been thought to be unreliable. The purpose of the present study was to evaluate the accuracy of lingular open lung biopsies in patients with bilateral diffuse pulmonary disease. Twenty consecutive patients with bilateral diffuse pulmonary disease underwent exploratory left thoracotomy when all noninvasive measures failed to arrive at a definitive etiology. Patients ranged in age from 24 to 79 with a mean of 52.6 years. There were five women and 15 men. Biopsy of the lingula was taken, as well as another area of similar lung involvement. Histopathologic results of the lingular biopsies correlated 100 percent with those from the other segments of the lung. The entire procedure, including rigid bronchoscopic examination, was routinely performed in less than one hour. In conclusion, lingular biopsies, relatively minor surgical procedures, are extremely accurate (100 percent) in making definitive diagnoses.

Adult↗