Neal W. Salomon

DIURESIS WITH CONTINUOUS INFUSION OF FUROSEMIDE AFTER CARDIAC SURGERY

We prospectively evaluated the diuretic effect of furosemide administered by bolus injection and by continuous infusion in 18 cardiac surgery patients. Nine patients were randomly assigned to receive 0.3 mg/kg of furosemide as a bolus injection at time 0 and again 6 hours later (nine patients) or 0.05 mg/kg per hour of furosemide as a constant infusion for 12 hours (nine patients). There were no significant differences between groups with respect to age, weight, creatinine clearance, changes in serum sodium and potassium levels, total urinary concentrations of sodium and potassium, or total urine volume for 12 hours. Diuresis during continuous infusion of furosemide was less variable from hour to hour than after bolus injection of furosemide and was sustained throughout the infusion period. Although the continuous infusion of furosemide will not provide the rapid and vigorous diuresis that is necessary in some clinical situations, it may be useful whenever a gentle, sustained diuresis is desired.

The Carpentier-Edwards pericardial aortic valve: Intermediate results☆

The Edwards pericardial aortic valve has unique design features that minimize cusp stress and reduce abrasion wear. Wear tests and in vivo fluid dynamic tests have shown superior performance compared with other bioprostheses. Between August 1981 and July 1985, 719 isolated aortic valves were implanted in 10 US centers. Patients were aged 18 to 90 years (mean, 64 years). Men were 63.3% of the patients. Aortic stenosis was present preoperatively in 63.4% of patients. New York Heart Association functional classes III and IV were assigned to 62% of the patients. Valve sizes were 21 mm or less in 49% of patients. Concomitant procedures (most often coronary artery bypass grafting) were performed in 48% of patients. Hospital mortality was 4.7%. There was one valve-related death due to anticoagulant hemorrhage. Late mortality yielded 23 valve-related deaths: endocarditis (13), anticoagulant hemorrhage (4), thromboembolism (3), structural (2), and pannus overgrowth (1). Freedom from valve-related death at 7 years was 95.5%. Regarding valve survival, cusp tears were not seen. There were 11 calcified valves and eight explants (57 to 107 months). Seven-year freedom from all valve reoperation was 95.5%, with 11% of the patients receiving warfarin sodium, freedom of the total series from hemorrhage at 7 years was 93.3%, and from major thromboembolism, 95.8%. Echocardiographic follow-up of hemodynamics at 7 years yielded the following calculated effective orifice areas: 19 mm, 1 cm2; 21 mm, 1.3 cm2; and 23 mm, 1.4 cm2. Average mean gradient for 19-mm valves was 15 mm Hg. New York Heart Association class improved in 78% of the patients. The Carpentier-Edwards pericardial valve, carefully studied by the Food and Drug Administration guidelines, is easy to use and has excellent hemodynamics.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Dopamine and Dobutamine Following Coronary Artery Bypass Grafting

A prospective, randomized comparison of the hemodynamic effects of dopamine and dobutamine was performed in 20 patients following coronary artery bypass grafting. Approximately 6 hours postoperatively, when patients were hemodynamically stable, either dopamine or dobutamine was administered at 2.5, 5.0, and 7.5 micrograms per kilogram of body weight per minute. At 5.0 micrograms/kg, both drugs increased cardiac index without changing heart rate, mean arterial pressure, pulmonary capillary wedge pressure, or peripheral vascular resistance. At 7.5 microgram/kg, dobutamine caused a further increase in cardiac index without changing the other variables. In contrast, increasing dopamine from 5.0 to 7.5 micrograms/kg/min caused significant increases in mean arterial pressure, pulmonary capillary wedge pressure, and pulmonary vascular resistance but no further increase in cardiac index. We conclude that dobutamine is preferable to dopamine in patients following coronary artery bypass grafting, since it produces consistent, dose-related increases in cardiac index without increases in heart rate, mean arterial pressure, pulmonary capillary wedge pressure, or pulmonary vascular resistance.

Plasma propranolol before, during, and after cardiopulmonary bypass

We evaluated changes in propranolol plasma levels before, during, and after cardiopulmonary bypass (CPB). Two groups of patients were studied, all of whom had been on long‐term propranolol and had received their last oral dose 10 to 15 hr before surgery. Approximately 100 min before CPB began group 1 patients (n = 7) received 0.1 mglkg propranolol intravenously while group 11 patients (n = 7) received a placebo. Before CPB the plasma propranolol levels fell in accordance with published descriptions for nonsurgical patients receiving oral and intravenous propranolol. Thereafter, the changes in the plasma levels were much the same in both groups. With the onset of CPB, the plasma levels decreased by approximately 50%. There was an insignificant fall in plasma levels during CPB, but the most interesting observation was made after: in each patient, the plasma levels obtained 5, 60, 120, and 240 min after CPB were higher than the last level during CPB. Mean plasma levels did not decline in either group during the 4‐hr period. Although the reason for the sustained rise in the propranolol levels after CPB is not known, we suggest that it is due to the redistribution of propranolol from the lungs to the plasma coupled with reduction in hepatic elimination.

Operative treatment of congenital aortic stenosis.

The operative treatment of 131 patients with congenital aortic stenosis is reviewed. Of the 131 patients, 77% had left ventricular outflow tract (LVOT) obstruction at a single level and 23%, major obstruction at more than one level. There were 3 operative deaths (2.3%) and 10 late deaths (7.8%). Twenty of the 128 discharged patients have undergone a second procedure and 6 a third procedure for recurrent or residual LVOT obstruction. The 26 reoperations included 7 aortic valve replacements, 4 left ventricular apical-abdominal aortic (LV-AA) valved conduits, and 15 extensive aortic valvotomies with or without supravalvular aortoplasty. Five of the 20 patients undergoing reoperation died; 4 of these deaths occurred in patients who had valve replacement at reoperation. The 4 who received LV-AA conduits have sustained excellent hemodynamic and clinical results with no complications. Highly satisfactory clinical results can be obtained with minimal operative risk, regardless of the level of LVOT obstruction. Reoperation for recurrent or residual LVOT obstruction, however, is comparatively more hazardous, and alternative surgical approaches (LV-AA conduits) should be considered.

Platelet loss during experimental cardiopulmonary bypass and its prevention with prostacyclin.

Prostacyclin (PGI2), a newly discovered short-acting prostaglandin that inhibits platelet aggregation, was evaluated as an agent for prevention of cardiopulmonary bypass-induced thrombocytopenia. Ten adult, splenectomized greyhounds were divided into three treatment groups prior to beginning 120 minutes of partial cardiopulmonary bypass. Group 1 animals received 300 units of heparin per kilogram of body weight, Group 2 animals received 300 units of heparin per kilogram plus PGI2, 1.5 micrograms per minute, and Group 3 animals received 300 units of heparin per kilogram plus PGI2 3.0 micrograms per minute. Bypass and PGI2 infusion were started simultaneously. Mean platelet counts of each group at 5 minutes were approximately 40% of prebypass levels. Additional platelet loss was seen in Groups 1 and 2 at 30, 60, and 120 minutes. However in Group 3, platelet counts at 30 and 60 minutes were essentially unchanged from prebypass levels. At 30, 60, and 120 minutes of cardiopulmonary bypass, the differences between Groups 1 and 3, and 2 and 3 are highly significant (p less than 0.01). We conclude that PGI2 is an effective agent for preserving platelet levels during experimental cardiopulmonary bypass. Furthermore, it is possible that platelet loss during cardiopulmonary bypass may be caused, in part, by an imbalance between PGI2 and thromboxane A2, which results in excessive platelet adhesion and aggregation.

Early experience with the intraluminal graft prosthesis

Surgical therapy for dissection of the thoracic aorta has been associated with a high mortality rate due in part to intraoperative bleeding at the suture lines and through the prosthesis. A technique has been devised to obviate some of these problems which utilizes a sutureless prosthesis that can be placed within the aorta. This device is now commercially available. Because of the infrequent use and the need to maintain a wide variety of lengths and diameters of these grafts, several Portland area hospitals jointly purchased grafts to reduce inventory and cost. From November 1981 through September 1982, four patients in two Portland area hospitals were treated with intraluminal grafts for descending thoracic dissections. All patients survived the surgical treatment and were discharged without complications. Based on a review of the literature and our initial experience, the intraluminal prosthesis appears to represent a significant improvement over conventional graft placement for treatment of both acute and chronic aortic dissection.

Two Dimensional Doppler Echocardiographic/M Mode Echocardiographic and Phonocardiographic Method for Study of Extracardiac Heterograft Valved Conduits in the Right Ventricular Outflow Tract Position

Significant concern exists over the long-term results of right ventricular outflow tract repair using heterograft valved conduits. Because these conduits and valves are difficult to image using ultrasound, a serially applicable two dimensional Doppler echocardiographic, M mode echocardiographic and phonocardiographic method for noninvasive investigation was developed and applied in 15 children. The method provides two dimensional echocardiographic imaging of valve contour and motion, as well as M mode and phonocardiographic analysis and quantitative range-gated Doppler information about the timing of flow through the conduit. Conduit diameter in two dimensional echocardiographic images correlated well with known conduit size (r = +0.96). A thickened and stenosed heterograft valve was predicted in two patients before hemodynamic investigation. This new method provides serially obtainable information to aid in the management of children and infants with a valved conduit placed for repair of congenital heart malformations and aids in planning the timing of hemodynamic follow-up studies.

Single Catheter Technique for Cardioplegia and Venting during Coronary Artery Bypass Grafting

Two areas of current controversy concerning coronary artery bypass operations involve the use of cardioplegia and the need for left ventricular venting. We wish to describe a very simple, safe, and effective method of accomplishing both cardioplegic arrest and venting using a single 14-gauge catheter inserted into the aortic root.

Comparison of two closed systems for thermodilution cardiac outputs.

The authors used an in vitro flow system to evaluate the sources of error in a previously described closed system thermodilution method for cardiac output determinations. Cardiac outputs were overestimated by as much as 49% because the injectate warmed as it was drawn through the connecting tubing. Submerging the tubing in the ice bath prevented this problem. The authors also evaluated a new closed system thermodilution cardiac output method. The method employed a bypass line and a spring loaded autosyringe which enables the user to flush the system with cold fluid, thereby ensuring accurate injectate temperatures. Cardiac output determinations with this method were as accurate as those obtained with a CO2 powered injector. Additionally, this method is easy to use, accommodates injection volumes of 1-10 ml, and is inexpensive.