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Biomedical subjects

L L Michaelis

Publications and source records attributed to L L Michaelis.

At least 37 records · Page 2Linked to original sources
PubMed1985

Interhospital transport of patients with ongoing intraaortic balloon pumping.

During a 5-year period (1979 to 1983), 50 consecutive patients undergoing continuous intraaortic balloon (IAB) pumping were transferred from Evanston Hospital to Northwestern Memorial Hospital (16 miles), where they underwent cardiac operation. All patients had cardiac catheterization before transfer. Indications for IAB were cardiogenic shock (9 patients), postinfarction angina (18 patients), unstable angina (9 patients), evolving myocardial infarction (3 patients), accelerating angina or hemodynamic instability during cardiac catheterization (9 patients) and prophylactic insertion for high-grade left main stenosis (2 patients). Transportation after stabilization was uneventful in all patients. All patients underwent operative coronary revascularization. There was concomitant mitral valve replacement in 3 patients, acute ventricular septal defect repair in 1 patient, aortic valve replacement in 1, and ventricular aneurysmectomy in 1. Three patients (5%) died postoperatively. Nine patients (20%) had complications directly related to IAB insertion. One patient required femoral-femoral arterial bypass preoperatively, 4 patients had postoperative lower limb ischemia treated by IAB removal or thrombectomy and 1 patient had thrombocytopenia (less than 60,000/mm3), 1 false aneurysm, 1 anterior compartment syndrome and 1 prolonged bleeding at the insertion site. Interhospital transfer with IAB pumping in progress should not be restricted to patients with cardiogenic shock, but can be effectively used for all patients who require preoperative IAB insertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Assisted Circulation↗
PubMed1985

Endocardial activation mapping and endocardial pace-mapping using a balloon apparatus.

The relation between endocardial activation mapping and endocardial pace-mapping was evaluated in 8 dogs while they were on cardiopulmonary bypass. Pacing or recording was accomplished by using a balloon apparatus (with 32 bipolar electrodes) inserted through a left apical ventriculotomy. Ventricular tachycardia (VT) was produced by occlusion followed by reperfusion of the left anterior descending coronary artery. During each VT, activation mapping was performed and early sites determined. Pace-map correlates (sites at which endocardial pacing produced a similar QRS morphology to that of the VT) were also determined. Isochronous maps were constructed for activation mapping and pace-mapping. There was a total of 29 morphologically distinct VTs. Groups were delineated according to correlations between activation mapping and pace-mapping. In 14 episodes of VT (group 1), pace-mapping confirmed the findings of activation mapping with all early sites being pace-map correlates (total number of early sites (tES) = 19; total number of pace-map correlates (tPMC) = 88; tES same as tPMC = 19). In 9 episodes of VT (group 2), there was a partial correlation between pace-mapping and activation mapping, such that pace-mapping when used with activation mapping appeared to further delineate the region of arrhythmogenesis (tES = 31; tPMC = 59; tES same as tPMC = 14). In 6 episodes of VT (group 3), there was no correlation between pace-mapping and activation mapping (tES = 15; tPMC = 0). With the balloon apparatus, endocardial activation mapping can be performed without the need for sustained monomorphic VT, and endocardial pace-maps may be generated easily.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Evaluation of the carbon dioxide laser for performance of gastrointestinal myotomies.

Using a conventional carbon dioxide laser set at 8-W continuous-wave energy, a technique was developed in the animal laboratory to incise only the muscularis of the pylorus leaving the mucosa and submucosa intact. Similar esophageal myotomies were performed with less success, due to the rich submucosal venous plexus causing obscuring hemorrhage and to the reapproximation of the longitudinal esophageal muscle over a 3-week period. The technique for esophageal myotomy requires further refinement, but pyloromyotomy appears applicable for controlled human trials.

Animals↗
PubMed1985

New applications of the laser in pulmonary surgery: hemostasis and sealing of air leaks.

In thoracic surgery, the laser has been used primarily as a destructive instrument (e.g., for extirpation of endobronchial lesions and for skin incisions). Previously, the carbon dioxide laser was used for its scalpel-like action but not for sealing. The neodymium:yttrium aluminum garnet (Nd:YAG) laser not only cuts but also seals blood vessels and bronchi. We have modified the CO2 laser technique to seal vessels and bronchi up to 3 mm on a cut surface by using low power in a defocused mode, and have evaluated the method in 12 dogs. Matched lesions in the lingula were sealed with each type of laser and compared with lesions closed by suture technique. These lesions were then evaluated at biweekly intervals up to 6 weeks following operation. All lesions demonstrated substantial air leak and bleeding prior to sealing. There was no bleeding or air leak (40 cm H2O of pressure) at any time after sealing (laser or suture). The CO2 laser sealing consistently produced the least damage both macroscopically and microscopically. However, this technique requires a relatively bloodless field. The Nd:YAG laser produced the deepest tissue destruction but functioned well under conditions of poor hemostasis. Suture closure produced large early injuries, which subsided gradually to approach the amount of damage seen with the CO2 laser. These studies demonstrate that the laser may be a useful adjunct to maximally preserve normal lung tissue and to seal bleeding, leaking, raw lung surfaces. Results of early clinical trials are also detailed.

Aged↗
PubMed1985

Management of chronic sternal osteomyelitis.

The management of 2 patients in whom chronic sternal osteomyelitis developed after apparently uncomplicated coronary artery bypass operations is described. Each patient had become totally disabled because of chronic, draining sinus tracts. Eradication of the infection required total sternectomy and excision of all infected costal cartilage. Subsequent reconstruction was accomplished by using bilateral pectoralis major myocutaneous advancement flaps without any maneuvers to stabilize the anterior chest wall. Both patients have resumed full activity and have returned to work with only minimal residual compromise of pulmonary function.

Aged↗
PubMed1985

Experimental air leaks in lung sealed by low-energy carbon dioxide laser irradiation.

When a focused carbon dioxide laser beam strikes a surface of tissue, the light energy is converted instantly into thermal energy, causing cells directly in the laser's path to vaporize. Because the carbon dioxide laser's energy is well absorbed by water, this thermal effect is attenuated at a distance of 100 mu. If the laser beam is "defocused," the same thermal energy is dissipated over a larger area, causing only desiccation and melting of tissue without vaporization; however, the depth of injury remains shallow. This modified technique has been used to seal artificially created air leaks in the canine lung. Twelve mongrel dogs were anesthetized, intubated, and ventilated. The lingula was exposed sterilely through a left thoracotomy. A 1 X 3-mm hole was made in the lung at 1 cm from the edge. The created air and blood leaks were sealed with a defocused carbon dioxide laser beam set at 8 W (32 W/sq cm). Each tissue "weld" withstood 40 cm H2O of peak ventilation pressure without leak. At the time of reoperation three weeks later, there was apparent complete healing of the pulmonary surface. No air leaks were present. Histologic examination showed a small zone of amorphous coagulated pleura and lung overlying a zone of minimal atelectasis. Normal lung was present within 150 mu of the laser seal. This new technique was performed safely and easily with currently available carbon dioxide lasers in the laboratory. It is presently undergoing intraoperative trials in a controlled clinical setting.

Animals↗
PubMed1985

Metastatic squamous cell carcinoma to the heart. Unusual cause of angina decubitus and cardiac murmur.

A 61-year-old woman was admitted to the hospital with the new onset of angina at rest and an ECG consistent with anterior wall ischemia. She was also noted to have a new cardiac murmur. Eighteen months earlier, she had been treated for squamous cell carcinoma of the base of the tongue. Thirteen months ago, she had local recurrence treated with radiotherapy, but had no evidence of recurrent or metastatic disease at the time of present admission. Echocardiography revealed intracardiac and extracardiac masses; surgical biopsy confirmed metastatic carcinoma to the heart which was responsible for her symptoms and the new murmur. Symptomatic cardiac metastases from squamous cell carcinoma is an unusual situation which, in this case, was easily diagnosed with echocardiography.

Angina Pectoris↗
PubMed1985

Complete surgical revascularization: the treatment of choice in young patients with multivessel coronary disease.

Since the advent of coronary angioplasty, nonoperative techniques to manage coronary artery disease have become attractive alternatives to coronary artery bypass grafting (CABG). To provide a standard against which new procedures could be judged, 123 consecutive patients less than 45 years of age who have had CABG since 1978 were systematically followed. The indications for operation were unstable angina or postinfarction angina (60%), life-threatening coronary anatomy with stable angine (36%), and sudden death or uncontrolled ventricular tachycardia (4%). Seventy-five patients had documented preoperative myocardial infarction, 55% within 30 days of CABG. An average of 3.2 vessels were grafted per patient; only 10 had single CABG. Complete revascularization was accomplished in 91% of patients. Five patients (4%) had myocardial infarction within 30 days of operation. No operative deaths or strokes occurred. The 6-year follow-up was 94.4% (the 5-year actuarial survival rate, 87.4%). There were four late deaths; two were due to myocardial infarction, one to prosthetic valve failure, and one to sudden death. At 2.7 years, 88.1% of the patients were NYHA Functional Class I; 85.4% continued full-time employment, and 98% considered their quality of life the same or better than before CABG. Five patients suffered myocardial infarctions during the follow-up period. Nine patients required reoperation: eight for graft occlusion (three less than 1 year, five greater than 3 years), and one for disease progression. These data confirm that complete operative revascularization remains the standard of therapy for young patients with multivessel coronary artery disease as evidenced by the absence of early mortality, the low incidence of morbidity, the excellent functional recovery, and the high return to gainful employment.

Journal Article↗
PubMed1985

Dose-related prolongation of the bleeding time by intravenous nitroglycerin.

The effects of intravenous nitroglycerin (NTG) upon the bleeding time, platelet aggregation response, and plasma 6-keto-PGF1 alpha concentration were measured in 17 patients about to undergo coronary bypass grafting. NTG produced a dose-related prolongation of the bleeding time that correlated with the accompanying decrease in systolic blood pressure. Platelet aggregation was not affected and measurements of 6-keto-PGF1 alpha failed to reveal detectable levels (less than 10 pg/ml) either before or after NTG infusion. This suggests that the prolonged bleeding time associated with NTG infusion may be due to vasodilation and increased venous capacitance, rather than altered vascular-platelet interaction.

Adult↗
PubMed1984

Pulmonary artery balloon counterpulsation for right ventricular failure: I. Experimental results.

The effects of pulmonary artery balloon counterpulsation (PABC) as a circulatory assist for the failing right ventricle were investigated. Sixteen anesthetized dogs underwent instrumentation to measure cardiac output and to record pressures in both ventricles, the pulmonary artery, and the aorta. Autonomic control of the heart was surgically and pharmacologically ablated. A specially designed counterpulsation balloon was inserted through the right ventricular (RV) outflow tract into the pulmonary artery. Pulmonary hypertension, induced acutely by the microembolization of the pulmonary circulation with glass beads combined with infusion of serotonin, served as a model for development of acute RV failure. Immediate effects of PABC were investigated in 10 dogs during normal function and failure of the right ventricle at different levels of preload. After further embolization which caused progressive cardiogenic shock, the effects of 10 minutes of PABC, and of its withdrawal, were examined. In all cases, PABC immediately decreased RV preload and afterload. In the failing right ventricle, counterpulsation also significantly increased cardiac output. Progressive cardiogenic shock was successfully reversed by PABC; after 10 minutes of counterpulsation, increases in cardiac output (+53%), arterial pressure (+55%), and RV minute work (+62%) were observed, paralleled by a fall in RV preload (-22%). After PABC was discontinued, the circulatory status again began to deteriorate. We conclude that PABC effectively improves function of the failing right ventricle caused by acute pulmonary hypertension.

Animals↗
PubMed1984

Pulmonary artery balloon counterpulsation for right ventricular failure: II. Clinical experience.

The use of pulmonary artery balloon counterpulsation (PABC) provided immediate salvage following cardiac surgical procedures in 2 patients with biventricular failure in whom inotropic drugs and intraaortic balloon counterpulsation did not provide sufficient support to allow weaning from cardiopulmonary bypass. Although both patients eventually died, the hemodynamic effectiveness of PABC was documented. The various clinical settings for right ventricular as well as biventricular failure are reviewed, the currently available options for treatment are summarized, and the directions for future laboratory investigation and possible clinical applications are presented.

Aged↗
PubMed1983

Changes in left ventricular performance related to perioperative myocardial infarction in coronary artery bypass graft surgery.

Strict electrocardiographic, enzymatic, scintigraphic, and hemodynamic criteria for perioperative myocardial infarction (MI) were defined and related to serial assessments of left ventricular performance during rest and exercise in patients seen early and late after coronary artery bypass graft operation. Global left ventricular performance was determined by radionuclide ventriculography from which changes in the pattern of serial postoperative ejection fractions (EF) were obtained. Patients were divided into two groups based on the presence or absence of perioperative MI, and were matched in pairs on the basis of preoperative EF and extent as well as location of coronary artery obstructions. The results indicate that neither short- nor long-term depression in resting EF occurred subsequent to perioperative MI. However, an exercise-related increase in EF eight months postoperatively was depressed in patients who had perioperative MI compared with those who did not. Patients with new Q waves and abnormal postoperative elevation in serum levels of the myocardial isoenzyme of creatine kinase (CK-MB) had a greater early decrease in EF compared with patients without evidence of perioperative MI. However, seven days after operation, the EF in both groups returned to preoperative levels. Patients with abnormal technetium 99m-pyrophosphate scintigrams had changes in perioperative EF similar to those in patients without MI. The presence of low cardiac output syndrome immediately after operation was associated with immediate and short-term decreases in EF, which were not seen in any of the other patient subgroups.

Cardiac Output, Low↗
PubMed1983

Operative therapy of malignant ventricular rhythm disturbances.

Pre- and postoperative electrophysiologic study (EPS), intraoperative cardiac mapping, and extended endocardial resection of scar (EER) has enabled us to identify subgroups among 94 patients who have had operation to control or prevent malignant ventricular arrhythmia. Operative mortality was 8.5% and cure or prevention of ventricular arrhythmia was accomplished in 92% of survivors. Group 1: 13 patients were resuscitated from "sudden death" due to ventricular fibrillation (VF). All had exercise-induced VF and/or ventricular tachycardia (VT). Preoperative EPS revealed no inducible VT/VF. All had coronary artery disease, without evidence of myocardial infarction (MI) or ventricular wall motion abnormality; all were cured with conventional myocardial revascularization. Group 2: 65 patients had MI with residual left ventricular wall motion abnormality, usually aneurysm. The malignant arrhythmia, either sustained VT (38 patients) or VF (27 patients), was inducible by EPS but not usually by exercise, and all were refractory to medical therapy. Treatment was operative mapping, aneurysmectomy, EER, and coronary revascularization. Operative mortality was 11.9%; 90% of survivors are arrhythmia free, off drugs; 10% are now drug responsive. Group 3: 3 patients without coronary disease had VT or VF caused by endocardial sarcoidosis or operative scar from a previous congenital heart operation. Treatment was EPS, operative mapping, and excision of abnormal endocardial scar with no operative mortality. Group 4: 13 patients underwent aneurysmectomy for indication other than arrhythmia, but had preoperative ventricular irritability which was not life-threatening. Operation was aneurysmectomy, prophylactic EER, and revascularization with no mortality and no postoperative arrhythmic events. After many years of unpredictable and unsatisfactory results from various empirical surgical approaches, the operative treatment of malignant ventricular arrhythmia is now based on sound electrophysiologic principles.

Arrhythmias, Cardiac↗
PubMed1983

The efficacy of medical stabilization prior to myocardial revascularization in early refractory postinfarction angina.

The timing of coronary artery bypass graft (CABG) surgery in patients with persistent, severe myocardial ischemia after an acute myocardial infarction is controversial. Based on the previous disappointing clinical experience with urgent surgery, a period of medical stabilization (mean ten days, range two to 28) prior to surgery was employed in a prospective nonrandomized clinical trial. The frequent use of intravenous nitroglycerin and intra-aortic balloon pumping was important in allowing preoperative clinical stabilization in these patients who were refractory to conventional medical therapy. The combined medical-surgical treatment protocol was associated with no early or late mortality in 20 patients who suffered preoperative myocardial infarction and demonstrated refractory post-infarction angina. Although these patients were considered to be high-risk surgical candidates, the incidence of perioperative myocardial damage in this selected group was comparable with that observed in patients undergoing elective CABG surgery at this institution without recent preoperative myocardial infarction. In order to determine the hemodynamic effectiveness of this selected patient management process, perioperative changes in left ventricular performance were determined by multigated cardiac blood pool imaging. Computer-based analysis of this radionuclide-related data allowed the accurate determination of ejection fraction (EF). Those patients with preoperative subendocardial infarction (N = 12) had no decrease in global EF 24 hours after operation and significant increases in EF seven days and eight months after operation. This pattern is analogous to that observed in patients without preoperative myocardial necrosis undergoing elective CABG surgery at this institution. Those patients with recent preoperative transmural myocardial infarction (N = 8) showed a decrease in EF 24 hours after operation, but recovered to preoperative levels seven days and eight months after operation. There was, however, no increase in EF in this subgroup of patients. On the basis of this study, the authors tentatively recommend a concerted effort at preoperative medical stabilization prior to CABG surgery in patients with persistent refractory myocardial ischemia soon after acute myocardial necrosis. A prospective, randomized study comparing urgent and delayed surgery, as well as nonsurgical treatment, will be necessary to define more precisely optimal management of this subgroup of cardiac patients.

Angina Pectoris↗
PubMed1983

Cardiac and renal responses to cross-clamping of the descending thoracic aorta.

The present study was performed to document the relative efficacy of commonly applied techniques used adjunctively during 1 hour of descending thoracic aortic cross-clamping. Renal and cardiac responses were determined by standard laboratory methods. There were four experimental groups: (1) heparin-bonded shunt; (2) partial femoral-femoral bypass; (3) sodium nitroprusside; (4) control. Each of the experimental groups showed abnormal hemodynamic responses during cross-clamping. Elevations in left ventricular end-diastolic pressure (LVEDP) and systolic blood pressure were common events during clamping, and cardiac output often decreased. Nevertheless, left ventricular performance curves after cross-clamping showed similar increases in left ventricular stroke work (LVSW) with increasing preload. In addition, left ventricular biopsy specimens showed preservation of myocardial high-energy phosphate stores and essentially normal ultrastructural integrity. Radioactive microspheres generally showed increased myocardial blood flow during and after cross-clamping, but no evidence of preferential subendocardial ischemia. Examination of renal function showed a marked decrease in urine output, glomerular filtration rate, and renal plasma flow during cross-clamping. Following the release of the cross-clamp, renal function returned to 50% to 85% of baseline status. Since we could find no major advantage of any of the techniques employed under the present experimental conditions, we suggest that all of the techniques should be part of the surgical armamentarium and the particular preoperative and/or intraoperative findings in a specific case should determine which technique is most appropriate for a given patient.

Adenosine Triphosphate↗
PubMed1982

Clinical evaluation of the relative effectiveness of multidose crystalloid and cold blood potassium cardioplegia in coronary artery bypass graft surgery: a nonrandomized matched-pair analysis.

Controversy exists concerning the most effective method of myocardial protection during coronary artery bypass graft operations. Accordingly, we performed a matched-pair analysis between 25 patients receiving multidose hypothermic potassium crystalloid cardioplegia and 25 other patients receiving cold blood potassium cardioplegia. Patients were matched on the basis of preoperative ejection fraction (EF) and the number of anatomically similar stenotic coronary arteries. The adequacy of myocardial protection was assessed by serial perioperative determinations of radionuclide ventriculography, hemodynamic measurements, analyses of electrocardiograms and serum levels of MB-CK. We found that the level of myocardial protection was similar between unstratified groups. However, when subgroups were selected on the basis of prolonged aortic cross-clamp time (greater than ninety minutes) or impaired preoperative left ventricular function (EF less than 40%), there was a suggestion that cold blood cardioplegia may be advantageous.

Adult↗