Long-term amiodarone administration protects against global myocardial ischemia.

Reports on the effects of amiodarone on cardiac function have been variable. This study addresses the effect of long-term amiodarone administration on recovery of cardiac function after a period of global ischemia. Normotensive and spontaneously hypertensive rats were used. Normotensive rats (n = 6) received 240 mg/kg amiodarone for 4 weeks, for a total of 72 +/- 3 mg. Hypertensive rats (n = 6) received 500 mg/kg amiodarone for 4 weeks, for a total of 116 +/- 5 mg. Final myocardial concentrations of amiodarone and desethylamiodarone were 1.85 +/- 1.75 and 0.50 +/- 0.61 micrograms/g wet weight for the normotensive rats and 1.30 +/- 0.58 and 0.31 +/- 0.17 micrograms/g for the hypertensive rats (p = nonsignificant). Equal numbers of controls received sterile saline solution for 4 weeks. The hearts were excised and perfused in a Langendorff apparatus. The results indicate that, after 15 minutes of normothermic ischemia, hearts treated with this relatively low dose of amiodarone recovered a greater percentage of preischemic work (97% +/- 13%) as compared with the controls (76% +/- 17%) (p less than 0.005).

Initial clinical experience with a more efficient hollow fiber oxygenator of unique design.

The first 90 cardiac surgery cases perfused with a new hollow fiber membrane oxygenator in which the gas flows through the fibers and blood flows around the fibers are reported. The fibers are microporous polypropylene with a pore size of 0.03 microns. Membrane surface area is 2.0 M2 and priming volume is 480 ml, including heat exchanger PaO2 is controlled by FIO2 and PaCO2 by gas flow rate. Patients as large as 2.36 M2 were perfused up to 348 min using hemodilution and hypothermia. The mean PaO2 was 200 mmHg and the mean PaCO2 39.5 mmHg. Oxygen transfer was as high as 230 ml/min. This low prime device transfers large volumes of gas, an efficiency which results from a crossed arrangement of the fibers to break up laminar flow of the blood around them. The low priming volume makes it appropriate for use in all but the smallest patients.

Early myocardial revascularization for postinfarction angina: results and long-term follow-up.

Within 30 days of acute myocardial infarction, 108 consecutive patients underwent urgent surgical myocardial revascularization for postinfarction angina between July 1976 and March 1983. There were 84 men and 24 women whose mean age was 59.6 +/- 9.5 years (range 34 to 80). Group I (15 patients, 14%) underwent surgery within 48 hours, Group II (47 patients, 43%) between 3 and 7 days and Group III (46 patients, 43%) within 30 days. Fifty-nine patients (55%) had transmural infarction. The ejection fraction was less than 40% in 21 patients (19%). Left ventricular end-diastolic pressure was 20 mm Hg or greater in 42 patients (39%). The incidence of single, double, triple vessel and 70% or greater left main coronary artery stenosis was 4, 20, 59 and 17%, respectively. There were two deaths (1.8%) within 30 days of operation. The incidence of intraaortic balloon pumping was higher in patients operated on earlier after myocardial infarction (53% of Group I versus 22% of Group III). Statistically, there were no differences in the use of inotropic agents or the occurrence of arrhythmias or postoperative myocardial infarction in the three groups. Late follow-up (mean 35 months, range 18 to 98) is complete for all patients (100%). There were four late myocardial infarctions and eight deaths. Actuarial survival was 87% at 5 years. Seventy-three percent of the 108 patients were free of angina and the condition of 14% improved. These results indicate that myocardial revascularization in the first 30 days after myocardial infarction can be accomplished with morbidity and mortality rates similar to those of an elective operation for chronic angina refractory to medical management.

Follow-up assessment of St. Jude Medical prosthetic valve in the tricuspid position: clinical and hemodynamic results.

Seven patients underwent postoperative right heart catheterization implantation of the St. Jude Medical prosthetic valve in the tricuspid position. Six patients were in atrial fibrillation at catheterization, and 1 was in normal sinus rhythm. At postoperative catheterization, the mean right atrial pressure ranged between 4 and 16 mm Hg (mean, 9.7 mm Hg); right ventricular systolic pressure was normal in 1 patient, mildly elevated (less than 50 mm Hg) in 4 patients, and moderately elevated (65 and 70 mm Hg) in 2. The cardiac output ranged between 3.0 and 7.0 L/min (mean, 4.2 L/min). There was no end-diastolic gradient across the St. Jude Medical prosthesis in 6 patients. The other patient had a gradient of 2 mm Hg across the valve when cardiac output was 7.0 L/min. On fluoroscopy, both discs demonstrated full excursion in all patients. These data demonstrate that a normally functioning St. Jude Medical valve in the tricuspid position does not create obstruction to forward flow, and they support use of this prosthesis in patients with tricuspid valve disease.

Early and late results following repair of partial atrioventricular (AV) canal.

Since 1961, 35 patients have undergone correction of partial AV canal. The mean age was 9.8 years (2 to 56 years). At cardiac catheterization, the ratio of pulmonary to systemic blood flow was greater than 2.5: 1 in 26 patients (74%) while pulmonary artery pressure was greater than 30 mmHg in 18 patients (51%). Mitral regurgitation was mild in 14 patients, moderate in 8 and severe in 3. The defect was closed with a patch in all patients. Mitral valvuloplasty was performed in 23 patients (68%) and no patient required valve replacement. There were no hospital or late deaths. Postoperatively, 22 patients were asymptomatic (NYHA I) while 13 were class II. There was no progression of mitral regurgitation in 8 years mean follow-up.

Initial clinical experience with a low pressure drop membrane oxygenator for cardiopulmonary bypass in adult patients.

The new Travenol oxygenator is composed of 80 parallel blood pathways. Microporous membrane separates the blood and gas compartments. The membrane surface area is 3 m2, with a pore size of 0.01 microns. Venous blood drains directly from the patient through the oxygenator, then through an integral heat exchanger and into a reservoir, from which a single arterial pump returns the blood to the patient. The advantage of this configuration of membrane oxygenator is simplicity of setup and operation. A disadvantage that we have observed is an apparent variation in resistance to blood flow through the oxygenator during clinical perfusion. Construction changes in a later version of the oxygenator have reduced the resistance to flow through the blood pathway. This device has been used for 20 perfusions at moderate hypothermia (mean 31.8 degrees C) in patients up to 2.1 m2 body surface area for up to 313 minutes. Blood flow was 2.1 to 5.6 liters/min, partial arterial oxygen pressure 100 to 394 torr, partial arterial carbon dioxide pressure 19 to 57 torr (mean 37 torr) and, arterial pH 7.29 to 7.56 (mean 7.41). Oxygen transfer was as high as 230 ml/min. This integral oxygenator-heat exchanger-reservoir is operated like a bubble oxygenator, with direct venous drainage through the device and a single pump, but it uses a membrane oxygenator for gas exchange to eliminate the detrimental effects of bubbles.

Consecutive repair of complex congenital heart disease using hypothermic cardioplegic arrest--its results and ultrastructural study of the myocardium.

Cold potassium cardioplegia was used in 78 consecutive patients undergoing correction of complex congenital heart disease between 1977 and 1982. Ages ranged from 4 weeks to 21 years (mean 6.7 years). The anatomical diagnoses were: tetralogy of Fallot (33), common AV canal (12), pulmonary atresia with ventricular septal defect (VSD) with previous shunts (5), transposition of great arteries (5), total anomalous pulmonary venous return (3), complex VSD (4), and complex anomalies (16). There were 3 deaths (4%). Electron microscopy was performed on biopsy specimens taken from the hypertrophied or volume-loaded cardiac chamber (1) before perfusion, (2) after cardioplegia, and (3) 30 minutes after cardioplegia. It showed near normal myocardial ultrastructure after cardioplegic arrest, however there was minimal mitochondrial and intracellular edema after reperfusion. Post-operatively, 80% of the patients had spontaneous defibrillation and only 10% required brief inotropic support. The operative exposure was excellent. No patient developed heart block during repair.

Long-term changes in canine vein graft after infusion of cardioplegic solution.

We have studied the effects of cardioplegic solution (CS) on angiographic and histologic anatomy of bilateral vein grafts interposed into the carotid arteries of 10 dogs for up to 1 year. One vein (exp) was infused with cardioplegic solution (pH 7.7, K + 25 mEq/l, temperature 12 degrees C) every 15 min four times at pressures up to 80 mm and then interposed into the carotid system. The other vein (con) was kept in cold Ringer's lactate (12 degrees C) before interposition. Six weeks and up to 1 year after bypass, angiograms showed 80% graft patency of exp and con grafts. Immediate histologic examination showed no detectable differences among veins before and after perfusion and con veins. Histologic examination at 1 year showed enlargement of the grafts, smooth muscle hyperplasia, and increase in collagen, as well as disorientation of muscle fibers; cytoplasmic vacuolation occurred with equal frequency in both exp and con veins. Perfusion of the vein segment with cardioplegic solution did not appear to be detrimental to vein patency or histologic appearance so that this can be considered a safe method for delivery of cardioplegia in jeopardized ischemic myocardium at the time of bypass surgery.

Clinical evaluation of the interpulse low resistance microporous membrane oxygenator.

The Interpulse microporous membrane oxygenator has been used in 100 patients for cardiac surgery. This oxygenator features transverse furrows in the membrane and a back and forth motion of the blood as it flows between the membranes. This pulsing motion causes secondary flows or vortices to occur in the furrows of the membrane. These secondary flows promote mixing of the blood in the film. This oxygenator has been used in a single pump circuit for perfusions for up to 343 minutes at a flow rate up to 5.9 l/min. Oxygen saturation has always been 98% or greater. The pulser rate of the oxygenator influences oxygen transfer, and the pulser rate has been regulated between 80 and 225 pulses per minute to achieve a mean arterial PaO2 of 207 mmHg. Carbon dioxide transfer is affected by the oxygen flow through the device and has been adjusted to between 0.2 and 7 l/min to obtain a mean PaCO2 of 40 mmHg in this series. This device has proved to be safe and effective in perfusions for cardiac surgery.

Percutaneous vs surgical placement of intra-aortic balloon assist.

Fifty-three patients required IABP over a one-year period. The type of insertion (percutaneous vs surgical) was used randomly. The hemodynamic effect, complication rate, and inability to insert the balloon were similar in both groups. Besides less trauma and cost-effectiveness, the most important advantage of percutaneous over surgical balloon insertion is shorter time interval between decision and insertion which thus allows faster stabilization of ischemic heart patients.

Successful correlation of type C complete atrio-ventricular (A-V) canal in infancy.

Herein, a successful repair of Type C complete A-V canal in infancy is reported. With a better understanding of anatomy as well as improved perioperative care it appears the primary repair is more reasonable approach than the high risk palliative operation (pulmonary artery banding), when surgery is required in such disease.

Computerized discrimination of microemboli in extracorporeal circuits.

A computerized ultrasonic particle detection system is capable of identifying microemboli in the 10 to 350 microgram. Data show that appropriate computer analysis of the reflecting signals allows discrimination of size and type of emboli. All extracorporeal circuits have microemboli with a large variation in size and number, depending upon the apparatus and how it is run.

Respiratory characteristics of a microporous membrane oxygenator.

A microporous membrane oxygenator has been used in 258 clinical perfusions for cardiac surgery. In 132 perfusions the oxygenator was ventilated with 100% O2, and in 126 perfusions 98% O2-2%CO2 was used. Patients' BSA was 0.4-2.3 M2. Bypass duration was up to 563 min. In the group ventilated with 100% O2, average PaCO2 was 30 mmHg, with arterial pH of 7.48. 98% O2-2% ventilation resulted in an average PaCO2 of 36 mmHg, with arterial pH of 7.41. CO2 transfer is influenced by gas flow rate, and data from selected cases demonstrate that increasing gas flow results in decreasing PaCO2, while decreasing gas flow increases PaCO2. The thickness of the blood film is decreased by increasing the "shim" pressure, so that increasing the "shim" presure results in higher PaO2. Oxygen saturation averaged 99% for the entire series. Addition of CO2 to the oxygen and appropriate changes in gas flow and "shim" pressure permit changes to be made in the ventilation of the device during perfusion to achieve desired levels of PaO2 and PaCO2 under widely disparate conditions of temperature and flow.

Total blood washout and exchange. A valuable tool in acute hepatic coma and Reye's syndrome.

Total body washout (TBW) was accomplished thirteen times in twelve patients, with response in five and survival in three. TBW can be done without apparent harm to patients and is less laborious and more rapidly effective than repeated exchange transfusion. Early application of TBW in stage III to stage IV hepatic coma may increase survival and possibly prevent progression of metabolic derangements. Patients with stage III to IV Reye's syndrome probably should have TBW promptly, without time-consuming attempts at exchange transfusion. Based on our experience, further application of TBW is warranted in coma due to acute hepatic failure and stage III to IV Reye's syndrome.