Renee S. Hartz

Impact of gender on coronary bypass operative mortality

BACKGROUND In spite of many reports investigating the influence of gender on coronary artery operations, it is still uncertain whether gender is an independent risk factor for operative mortality. A major problem of previous reports has centered around the fact that men and women constitute quite different populations, thereby making direct comparisons difficult. METHODS The Society of Thoracic Surgeons National Cardiac Surgery Database was used to retrospectively examine 344,913 patients undergoing coronary artery bypass graft operations from 1994 through the most recent data harvest. The operative mortality of male and female patients was compared for a variety of single risk factors and combinations of risk factors. A logistic risk model was used to account for all important patient parameters so that individuals could be stratified into comparable categories allowing for direct comparisons of risk-matched male and female patients. RESULTS The univariate analysis showed that the 97,153 women carried a significantly higher mortality for each of the risk factors examined. The multivariate analysis and the risk model stratification showed that women had significantly higher mortality as compared to equally matched men in the low- and medium-risk part of the spectrum, but in high-risk patients, there was no difference between male and female mortality. CONCLUSIONS Gender is an independent predictor of operative mortality except for patients in very high-risk categories.

Prophylaxis of Supraventricular Tachyarrhythmia after Coronary Bypass Surgery with Oral Verapamil: A Randomized, Double-Blind Trial

This study investigated the efficacy of oral administration of verapamil, started 24 hours after coronary artery bypass grafting (CABG), in reducing the incidence of postoperative supraventricular tachyarrhythmia (SVT). Two hundred patients were randomly assigned in a double-blind fashion to receive a one-week course of either a placebo or 80 mg of verapamil every 6 hours. Overall, SVT developed in 23 control and 14 verapamil-treated patients, a 39% reduction in incidence (p less than 0.10). Of the patients who received at least four doses and continued to receive the study drug, 17 in the control and 7 in the verapamil group experienced SVT, a 53% decrease in incidence (p less than 0.06). Atrial fibrillation constituted 34 of the 37 SVT episodes and was associated with a slower ventricular response in the group given verapamil (115 +/- 8 versus 156 +/- 4 beats per minute; p less than 0.001). No evidence was found linking postoperative SVT with the withdrawal of beta-blocking drugs. Adverse effects required that 20 patients in the verapamil and 6 in the placebo group be removed from the study. Hypotension or pulmonary edema or both developed in 13 of the patients receiving verapamil, but in only 1 of the control patients (p less than 0.001). We conclude that although verapamil has potential merit for the prophylaxis of SVT after CABG, its use in this setting is associated with a high incidence of unacceptable hemodynamic side effects.

Fiber Size and Energy Metabolites in Five Separate Muscles from Patients with Chronic Obstructive Lung Disease

The purpose of this study was to examine whether morphologic abnormalities in human respiratory muscles are related to increased airway obstruction. 43 patients who were undergoing thoracotomy for suspected neoplasm had biopsies taken from one or more of the following muscles: external intercostal (EXT), internal intercostal (INT), diaphragm (DIA), latissimus dorsi (LAT), and quadriceps femoris (LEG). Mean FEV1/FVC was 65% of predicted (range 43–90%). 21 of the 43 patients had a malignancy. Atrophy of type I fibers was found in 27% of respiratory and 11 % of nonrespiratory muscles. Type II fiber atrophy was more common, being found in 58% of all muscles studied. The degree of type II fiber atrophy correlated significantly with the amount of weight loss, but not with age or the presence of malignancy. A unique and significant relationship was found between type II fiber atrophy in the INT (an expiratory muscle) and all measured indices of airway obstruction. This relationship did not exist in the DIA, EXT, or LAT, ordinarily considered muscles of inspiration. The percentage of type I and type II fibers bore no relationship to indices of airway obstruction. Depletion of muscle metabolites was common to all muscles and could not be related to airway obstruction or fiber atrophy. These data suggest that fiber atrophy and metabolite depletion occur commonly in both respiratory and nonrespiratory muscles in patients with stable obstructive lung disease. These changes probably reflect a generalized disease process and may predispose to muscle fatigue. Whether or not airway obstruction produces fiber atrophy in expiratory muscles requires further investigation.

Clinical experience with portable cardiopulmonary bypass in cardiac arrest patients

To evaluate the use of portable cardiopulmonary bypass as a resuscitative tool and its impact on long-term survival of patients in cardiac arrest, we reviewed the results of 32 consecutive patients resuscitated by cardiopulmonary bypass for cardiac arrest or severe hemodynamic compromise at Northwestern Memorial Hospital over a 2-year period. Overall survival was 12.5%. Only 1 (3.4%) of the 29 patients who had cardiac arrest survived and left the hospital. All 3 patients who had severe hemodynamic compromise but not cardiac arrest were long-term survivors. Our study suggests that portable cardiopulmonary support systems used as a resuscitative tool do not prolong the survival of most cardiac arrest patients but may be useful for patients with shock due to mechanical causes and for those with profound hemodynamic compromise due to ischemia or myocardial infarction. Portable heart-lung machines can provide patients with excellent hemodynamic support; however, neurological or cardiac recovery is unlikely once cardiac arrest occurs.

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.

Vascular anastomoses with laser energy

Laser-assisted arterial and venous anastomoses are now feasible. A microscope-guided CO2 laser was used to deliver 60 to 100 mW to anastomose end to end 44 rabbit carotid arteries (1.5 to 2.0 mm) and 27 rabbit vena cavae (4 to 6 mm). These were compared with control arteries repaired with interrupted suture technique. Anastomoses were examined from between 24 hours and 19 weeks. Laser carotid anastomoses yielded 93% patency (41 of 44) and 9% aneurysms (4 of 44), whereas hand-sewn carotid anastomoses produced 91% patency (40 of 44) and no aneurysms. In the vena cava, 26 of 27 laser anastomoses were patent (96%) compared with 19 of 20 (95%) sutured controls. Venous aneurysmal dilatation was seen in 2 of 27 laser (7%) and in 3 of 20 (15%) hand-sewn anastomoses. Histologic examination of laser-assisted anastomoses showed local full-thickness thermal injury. Repair was by fibroblast and myofibroblast proliferation, and luminal cell coverage was complete by 14 days in both laser and sutured repairs. Laser arterial and venous anastomoses are attractive because of their simplicity and rapidity of performance. Their patency is comparable to sutured anastomoses, but arterial aneurysms remain a hazard despite use of extremely low laser energy.

Comparison of transesophageal and transthoracic echocardiography for diagnosis of right-sided cardiac lesions

Abstract Two-dimensional transthoracic echocardiography (TTE) is an established method for the evaluation of cardiac or paracardiac structural abnormalities such as tumors, vegetations and thrombi. 1–4 Cardiac structural resolution can be limited with TTE owing to anatomic interference. With transesophageal echocardiography (TEE), regions of the heart previously difficult to visualize are now readily studied. These regions include the vena cavae, right ventricular outflow tract, pulmonic valve and pulmonary trunk. The usefulness of TEE as compared with TTE in assessing right-sided cardiac pathology has not been clearly determined. We compared both techniques with the objectives of studying their diagnostic ability for the evaluation of right-sided cardiac lesions, and comparing data obtained with those from other confirmatory techniques.

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)

Arterial aneurysm model using laser energy

Abstract Continuous wavelength laser energy can be used to perform arterial anastomoses, but all experimental series report an incidence of anastomotic aneurysm formation. To elucidate the mechanism of aneurysm production, controlled injuries of the arterial wall were created with a pulsed CO2 laser beam (40–50 mW). One carotid and one femoral artery of 10 New Zealand rabbits were injured with laser and the contralateral vessel was exposed surgically as a sham operation. At reoperation 8 to 11 weeks later, all 40 arteries were patent. None of the carotid shams, one carotid laser, two femoral shams, and eight femoral laser vessels (80%) were aneurysmal. Histologic examination revealed extensive medial necrosis with fragmentation of the internal elastic lamina in the area of these aneurysms. Femoral vessels were significantly smaller than carotids (P

New uses of the laser in thoracic and cardiovascular surgery.

Lasers have been accepted in general thoracic surgery as resectional tools which allow precise hemostasis and maximal salvage of normal lung tissue. Used endoscopically, with or without associated photodynamic therapy, we have provided acceptable palliation in some patients with obstructing tumors of the tracheobronchial tree and esophagus. Cardiovascular uses of the laser have been under extensive investigation at our medical center for many years. We have demonstrated that laser-assisted anastomosis of small vessels is possible, that early tensile strength and patency are excellent, but that long-term aneurysm formation is excessive. In addition, CO2 laser injury of the arterial intima leads to a marked increase in atheromata formation in animal models of atherosclerosis; this may be eliminated with the excimer laser. We have begun using the excimer laser to open obstructed peripheral and coronary arteries. New technology is emerging which allows dual fiber catheters which allow identification of tissue in an artery,ie calcium, atheromata, clot, media, etc. and instantaneous computer sensing/integration which initiates “fire” or “no fire” signals in the enclosed laser system, thus decreasing the chance of vessel perforation. These technologies, in association with balloon angioplasty, intravascular stents, and atherectomy devices are offering exciting alternate therapy for patients with obstructing atherosclerosis.