Clinical images: Libman-Sacks endocarditis.
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Adult↗
Biomedical subjects
J B Riebman
Publications and source records attributed to J B Riebman.
Upper extremity vascular access for continuous arteriovenous hemofiltration and dialysis after cardiac operations.
BACKGROUND: There is increasing interest in the use of continuous arteriovenous hemofiltration/dialysis for treatment of profound renal failure after cardiovascular operations. Vascular access for this is usually accomplished by percutaneous cannulation of the femoral artery and vein, with the inherent risks of vascular trauma, patient immobilization, hemorrhage, or infectious complications. METHODS: Fifteen (0.36%) of 4,166 patients receiving cardiovascular surgical procedures sustained postoperative renal failure requiring treatment with continuous arteriovenous hemofiltration/dialysis. Each patient had creation of acute arteriovenous forearm access using a modified Allen-Brown shunt. Shunts were monitored continuously for hemorrhage, malfunction, infection, and thrombus, and were explanted when no longer required. RESULTS: Sixteen shunts were implanted in 15 patients over the 41-month period. All shunts functioned satisfactorily, with the duration of implantation ranging from 1 to 64 days. There were no infectious or hemorrhagic complications. CONCLUSIONS: The acute creation of a simple forearm shunt for postoperative continuous arteriovenous hemo-filtration/dialysis is preferred over femoral arterial and venous cannulation because it can be constructed rapidly and easily in the operating room or at the bedside, has a low complication rate, is available for immediate use, may be left in place indefinitely, does not interfere with patient mobilization or ambulation, and is easily removed.
Acute Kidney Injury↗
The impact of aprotinin on coronary artery bypass graft patency.
STUDY DESIGN: Aprotinin has recently been shown to reduce postoperative bleeding and transfusion requirements associated with coronary artery bypass grafting. One concern with its use, however, is that it may have a deleterious effect on graft patency because it promotes hemostasis. Forty-seven patients undergoing coronary artery bypass. Forty-seven patients undergoing coronary artery bypass grafting were enrolled in a prospective, randomized double-blind trial of aprotinin to determine the effect of this agent on postoperative bleeding, transfusion requirements, renal function, and graft patency. The study group was comprised of the 32 patients who underwent technically adequate ultrafast CT scans 6 to 8 weeks postoperatively to determine graft patency. Sixteen patients received aprotinin (aprotinin group) and 16 received placebo (control group). RESULTS: Demographic and operative descriptors were comparable between groups. Postoperative mediastinal and chest tube drainage in the aprotinin group was significantly less than that in the control group (722 vs 1,540 mL; p = 0.0006) and the mean blood transfusion requirements were less, but this did not reach significance (125 vs 297 mL; p = 0.42). Analysis of graft patency by patients revealed that 5 patients in the aprotinin group (31%) had at least one occluded graft, while none of the patients in the control group had an occluded graft (p = 0.04). Analysis by graft revealed that 38 of 43 grafts placed in the aprotinin group were patent, while all 38 grafts placed in the placebo group were patent (88.4 vs 100%; p = 0.057). There was no difference in the incidence of myocardial infarction, renal dysfunction or hematologic indexes at discharge between the groups, or evidence of other thrombotic complications. CONCLUSION: We conclude that high-dose aprotinin is effective in reducing hemorrhage after coronary artery bypass grafting. However, its routine use should be approached cautiously due to its possible adverse effects on graft patency.
Aged↗
Improved technique for pleural drain insertion during cardiovascular surgery.
We describe an improved technique for pleural drain insertion during cardiovascular procedures performed through a median sternotomy. Benefits of this technique include less patient discomfort, optimal drain geometry, and reduced risk of pneumothorax on drain removal.
Chest Tubes↗
Prophylactic procainamide for prevention of atrial fibrillation after coronary artery bypass grafting: a prospective, double-blind, randomized, placebo-controlled pilot study.
OBJECTIVE: To evaluate the effect of prophylactic procainamide on the frequency of postoperative atrial fibrillation in patients undergoing myocardial revascularization. DESIGN: Prospective, randomized, double-blind, placebo-controlled pilot study. SETTING: Surgical intensive care unit and wards at a university hospital affiliate. PATIENTS: A total of 46 patients undergoing myocardial revascularization. INTERVENTIONS: Twenty-two patients received procainamide (procainamide group) and 24 patients received placebo (control group). Procainamide was administered to the procainamide group within 1 hr of the patient's arrival in the intensive care unit and consisted of an intravenous loading dose (12 mg/kg) followed by a maintenance dose (2 mg/min) of procainamide. The control group received a similar volume of placebo. When the patient was able to take oral medication, the study drug was administered orally in a weight-adjusted dosage. MEASUREMENTS: Electrocardiograms (EKGs) were continuously monitored. Procainamide and N-acetyl procainamide serum concentrations were measured, and the dosages in the procainamide group were adjusted by an independent observer. The study drug was continued for 5 days or until an event occurred that resulted in dismissal from the study. MAIN RESULTS: The procainamide group and control group had similar preoperative demographic descriptors and operative variables, except for the mean left ventricular ejection fraction, which was lower in the control group than in the procainamide group (60% vs. 68%, p = .03 [Wilcoxon rank-sum test]). There were no hospital deaths. The number of episodes of postoperative atrial fibrillation was significantly reduced in the procainamide group (5 episodes in 129 patient days at risk [3.9%/day at risk]) compared with the control group (17 episodes in 161 patient days at risk [10.6%/day at risk], p = .04 [Fisher's exact test]). Complication rates were similar in both groups. CONCLUSIONS: In a pilot trial, prophylactic procainamide reduced the number of episodes of atrial fibrillation in patients after coronary artery bypass grafting. Procainamide also decreased the number of patients who experienced postoperative atrial fibrillation. However, due to the small sample size, this latter difference was not statistically significant. Further studies are needed to confirm this encouraging trend.
Aged↗
The impact of intraoperative autotransfusion on cardiac surgery. A prospective randomized double-blind study.
The effect of intraoperative autotransfusion during coronary artery bypass grafting was studied in a randomized double-blind trial involving 38 patients. Nineteen patients had the collected RBCs washed and autotransfused (autotransfusion group), while the remaining patients had their washed cells discarded (control group). Postoperative hemoglobin and hematocrit values were similar. Exposure to banked blood was markedly decreased in the autotransfusion group compared with the control group. In addition, the mean volume of banked packed RBCs transfused per patient was significantly less in the autotransfusion group compared with the control group. Platelet utilization also was markedly decreased in the autotransfusion group. Cryoprecipitate and fresh frozen plasma utilization also was less in the autotransfusion group than in the control group, but this did not reach statistical significance. We conclude that the intraoperative use of autotransfusion decreases the volume of homologous blood products transfused, which results in reduced exposure of the patients to banked blood products.
Adult↗
Mechanical left ventricular assist: progress and new horizons.
This review traces both the progress and the scope of mechanical devices developed to assist or substitute the functions of a failing heart. The present states of art, particularly the clinical results of their application, are briefly summarized. Physiological and engineering issues confronting us today and a number of newer concepts in mechanical cardiac assist are then discussed in perspective.
Heart-Assist Devices↗
Volume homeostasis in calves with artificial atria and ventricles.
We examined whether replacement of cardiac atria and ventricles with total artificial hearts (TAH), a procedure that removes cardiac nerves and all sources of atrial natriuretic factor (ANF), would cause alterations in volume homeostasis in awake calves. Preoperatively, extracted plasma immunoreactive (ir)ANF levels were 13.3 +/- 0.6 and remained postoperatively at 10.5 +/- 0.4 pg/ml (P less than 0.01). TAH implantation caused systemic and pulmonary hypertension (P less than 0.01), salt retention, edema, and significant elevations of plasma renin, aldosterone, and arginine vasopressin. In intact calves rapid infusion of 6 liters of normal saline raised irANF levels to 73.7 +/- 6.5 pg/ml (P less than 0.01) and elicited a large natriuresis and diuresis. No such response to 6 liters of normal saline was obtained after calves had recovered from TAH implantation. Reduction of cardiac output (CO) by 50% caused further salt retention and no change in irANF levels. Elevation of CO back to and 33% above base line produced only a diuresis, whereas salt retention persisted and irANF levels remained unchanged. The same maneuvers elicited in surgical control calves (artificial ventricles only, largely intact atria) a significant increase in irANF levels and a diuresis and natriuresis. In conclusion, alterations in volume homeostasis observed after TAH implantation seem to be the consequence of at least two pathophysiological mechanisms: 1) functional ANF "deficiency," characterized by apparently unregulated ANF secretion from noncardiac sites, and 2) cardiac denervation.
Animals↗
Preclinical evaluation of the abdominal aortic counterpulsation device.
A valveless, single-orifice abdominal aortic counterpulsation device (AACD) was implanted retroperitoneally on the abdominal aorta and was pumped continuously, providing aortic diastolic augmentation for 45 +/- 4.9 days in four calves (group A). The hematocrit, lactate dehydrogenase (LDH), bilirubin, blood urea nitrogen, and creatinine were obtained before implantation and weekly thereafter. Biocompatibility data were compared to those obtained from 11 calves (group B) that received a total artificial heart (TAH) and were electively terminated 50.0 +/- 19.5 days after implantation. The hematocrit values in the first week were 20.9 +/- 11.5% and 39.8 +/- 11.5% below control values for group A and group B, respectively (p less than 0.02); in the sixth week they were 5.1 +/- 14.6% above control values (group A) and 22.6 +/- 9.0% below control values (group B) (p less than 0.05). LDH did not change in group A, while in group B it was constantly about 100% above control values. Autopsy revealed one to three infarcts 1 to 3 mm in diameter in 63% of the kidneys in group A, while in all of group B kidneys there were multiple infarcts of more than 10 mm. After the induction of left ventricular (LV) failure, the AACD decreased the LV end-diastolic pressure (EDP) by 21.2% (p less than 0.005) and the aortic (AO) EDP by 18% (p less than 0.005). It increased the endocardial viability ratio by 300% (p less than 0.0005), and the cardiac index by 66.9% (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Regulation of pneumatic total artificial heart function: a review.
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Cardiac Output↗
Development of smaller artificial ventricles and valves made by vacuum forming.
Implantable prosthetic ventricles and trileaflet valves made by vacuum forming have been developed and implant tested. All components are made from Pellethane. Recognizing the need for smaller as well as larger ventricles, designs with effective stroke volumes of 50, 85, 100 and 130 cc have been tested with several valve types. The pneumatically driven Utah ventricular assist device (UVAD) can be used as a total artificial heart (TAH) or ventricular assist device (VAD) by using the appropriate inflow and outflow adapters. In vitro durability testing has demonstrated ventricular lifetime beyond two years and valve lifetime to nearly one and one half years. The polymer valves have lower regurgitation than mechanical valves. Animal implantation experience includes 21 TAH implants and 16 left ventricular assist device (LVAD) implantations. TAH survival ranges from 2 to 210 days. LVAD animals have lived up to 116 days before elective termination. The animal were healthy and grew normally. The devices exhibit a "Starling's Law" response. One TAH animal survived 72 days before successful explantation followed by transplantation. At autopsy, this animal had no renal infarcts. Hematology data has demonstrated the existance of little or no intravascular hemolysis (PF Hb less than 5 mg%). The "Philadelphia" version of the UVAD vacuum formed ventricles are small enough to be implanted without thrombus provoking connectors. Eight animals have received this TAH and survived up to 120 days. Vacuum forming offers a rapid and inexpensive way to produce reliable and effective total artificial hearts and valves for widespread, temporary clinical application in any size adult human.
Animals↗
Hemodynamic and energetic assessment of calves implanted with a left ventricular assist device (LVAD).
Hemodynamic and ventricular energetic parameters were measured in calves implanted with the air driven Utah Ventricular Assist Device (UVAD). Uptake site was varied to determine the effect of control mode and vacuum augmentation of filing. Uptake was drawn solely from the left atrium or combined with a left ventricular apical vent. LVAD outflow returned to the descending, thoracic aorta. Control modes examined included asynchronous pumping as well as 1:1 and 1:2 synchronous diastolic counterpulsation. The 85cc LVAD, vacuum formed from PELLETHANE, was implanted acutely in four animals and chronically in six (7, 49 and 116 days paracorporeally, 1, 28 and 32 days intrathoracically). Instantaneous blood pressures, intramyocardial pressure, aortic outflow, oxygen consumption, LVAD output and drive parameters were recorded. LVAD output was independent of control mode when the natural heart rate was greater than or equal to 80 beats per minute. Intrathoracically positioned LVADs pumped a mean flow of approximately equal to 5 liters/min without vacuum augmentation of filling. Paracorporeally positioned LVADs pumped approximately equal to 3 liters/min mean flow without vacuum augmentation and up to approximately equal to 6 liters/min with 38 mm Hg of vacuum augmentation of filling. Instantaneous ascending aortic pressure and flow showed distinct beat-to-beat variation depending on LVAD control mode. Lower average ventricular afterload was observed when pumping the LVAD asynchronously or 1:2 synchronously. In one acute preparation, left ventricular myocardial oxygen consumption was reduced from the unassisted average control level by 37% for the asynchronous and 1:1 synchronous control modes with left atrial uptake.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The total artificial heart: indications and preliminary results.
The development of the total artificial heart (TAH) has reached a level where it is now available for clinical applications. The TAH has demonstrated distinct advantages over other forms of mechanical circulatory assistance. As of December 1, 50 TAHs have been implanted: 5 as permanent devices, and 45 as a temporary mechanical bridge to cardiac transplantation. The use of the TAH has increased in the last several months, leading to a growing interest in defining the indications and contraindications to its use. End-stage cardiomyopathy (either idiopathic, ischemic, viral, or postpartum) has been the underlying disease in 80% of the TAH procedures to date. The TAH has also been applied in 5 cases of acute cardiac graft rejection, 2 cases of congenital heart diseases, and in one case after acute myocardial infarction. The indications for the use of the TAH in these and other potential patient groups is discussed in light of the current clinical results.
Cardiomyopathies↗
The artificial heart in human subjects.
In preparation for clinical implantation of the Utah J-7 pneumatic artificial heart as a permanent cardiac substitute, the device was implanted into five brain-dead human subjects. This report presents our results and details our two most successful trials. Three different surgical implant techniques were utilized in the five subjects. Because of the unique "no risk" situation of the subjects, the function of the artificial heart could be tested in a manner not advisable in patients, but necessary for clinical preparation. The implantable total artificial heart was able to maintain physiological hemodynamics in two subjects for 41 and 72 hours at which time the trials were electively terminated.
Blood Pressure↗
Regulation of pineal rhythms in chickens: N-acetyltransferase activity in homogenates.
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Acetyltransferases↗
The pineal gland: a biological clock in vitro.
Circadian rhythmicity was studied by following the course of N-acetyl-transferase activity in the pineal glands of chickens in vitro. The results indicate (i) a daily change during day 1 of organ culture in constant dark that was dependent on the time the chickens were killed, (ii) equivocal persistence of the daily change in constant dark during 6 to 7 days of organ culture, (iii) an effect of light, (iv) inhibition by adrenergic agents and cycloheximide, and (v) stimulation by dibutyryl adenosine 3',5'-monophosphate and related compounds.
Acetyltransferases↗
Regulation of pineal rhythms in chickens: inhibition of dark-time N-acetyltransferase activity.
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Acetyltransferases↗