Biomedical subjects
Publications and source records attributed to D M Rose.
This case report discusses one method of dealing with the extensively calcified aorta in patients undergoing open heart surgery. Profound hypothermia and circulatory arrest was used in a patient undergoing aortic valve replacement with severe calcification of the ascending aorta and transverse arch. This patient recovered from surgery and was discharged from the hospital with no neurologic deficits.
Paraplegia following insertion of an intra-aortic balloon is an extremely rare and unusual complication with only one previous report in the literature. We recently encountered this problem in a man with severe coronary disease and unstable angina. The etiology of this complication, although never established in our patient, was most likely a critical occlusion of a spinal cord artery as a result of either a small dissection or an arterial embolus.
Short-term experimental studies have indicated that initial reperfusion with blood cardioplegia may decrease ischemic injury after aortic occlusion; however, no long-term studies have been performed. We evaluated cardioplegic reperfusion in fifteen dogs, divided into three groups of five each. Group I underwent 2 hours of cardiopulmonary bypass at 37 degrees C. Group II underwent 2 hours of cardiopulmonary bypass, including 1 hour of ischemic arrest, at 25 degrees C. Group III was identical to Group II, but the hearts of the animals were initially reperfused with 500 ml of blood cardioplegia at 25 degrees C (K+ = 30 mEq/L). Stroke work index (SWI), left ventricular end-diastolic pressure (LVEDP), dp/dt max and maximal contractile element velocity (Vpm) were measured preoperatively, immediately after operation, 21 days postoperatively, immediately after operation, 21 days postoperatively and 120 days postoperatively. Compliance curves were evaluated using an intraventricular balloon at 120 days. Groups II and III had significant (p less than 0.05) elevations of LVEDP at all three postoperative measurements. The hearts of the Group III animals (cardioplegic reperfusion group) demonstrated significantly (p less than 0.05 to 0.01) better recovery of SWI immediately after operation (62% versus 39%), at 21 days (85% versus 69%), and at 120 days (81% versus 66%) than did those in Group II. However, groups II and III had decreased compliance at 120 days, compared with that of Group I, and also showed both gross and microscopic evidence of subendocardial necrosis and fibrosis. It is concluded that while initial reperfusion with blood cardioplegia appears to provide better preservation of ventricular function early after ischemic cardiac arrest, this technique does not prevent later deterioration of ventricular compliance. Moreover, it produces myocardial fibrosis.
Since July, 1978, we have inserted a roller pump type of left heart assist device between the left atrium and ascending aorta in 35 patients. There were no significant complications related to use of the device. Seventeen patients recovered sufficiently to have the device removed. There were four early deaths, 60 to 120 days following removal of the device. Three of these patients died of septic complications and one patient died as a result of a cardiac arrest. Of the 13 long-term survivors, seven are working and six are retired. Five patients have mild to moderate cardiac symptoms, whereas eight others are completely asymptomatic. In three patients the ejection fraction was significantly lower than preoperatively; however, in all other patients the ejection fraction either stayed the same or improved postoperatively. We conclude that this type of left heart assist device can provide adequate cardiac support in patients with profound left ventricular dysfunction following cardiac operations. Furthermore, surviving patients generally have satisfactory long-term cardiac function and are leading productive lives.
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Only four instances of isolated chylopericardium following cardiac operation have been reported previously. We encountered this complication in a young patient who was operated on for infundibular pulmonary stenosis. The etiology appears to be related to a combination of intraoperative lymphatic injury and catheter-related subclavian vein thrombosis, the latter potentially elevating pressure within the thoracic duct and thereby resulting in an accumulation of chyle within the pericardial space. Therapy for this problem usually includes partial pericardiectomy with or without ligation of the thoracic duct.
The effect of reduced hemoglobin (Hb) on in vitro human polymorphonuclear leukocyte (PMNL) bactericidal activity was investigated. Addition of Hb at physiologic concentrations and oxygen partial pressures (150 mg/ml, 35 torr) to PMNL bactericidal assays significantly inhibited the killing of blood culture isolates of Escherichia and Staphylococcus aureus. Raising the oxygen partial pressure above 35 torr greatly decreased this inhibition. Carboxy hemoglobin, produced by equilibrium of Hg with carbon monoxide, is unable to bind oxygen and did not inhibit PMNL bactericidal killing. We postulate that reduced Hb may scavenge oxygen near the surface of the PMNL therapy preventing utilization of oxygen by PMNL for maximal bactericidal activity.
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During the period from July 1, 1978 to Dec. 31, 1980, we employed a partial left heart bypass (left atrium to ascending aorta) in 16 patients who could not be weaned from cardiopulmonary bypass with inotropic agents and the intra-aortic balloon pump. Flow rates up to 3,500 ml/min could be obtained with this device. Eight of the 16 patients survived and left the hospital. One patient died of a cardiac arrest 4 months postoperatively and one has recurrent angina and moderate congestive heart failure 24 months postoperatively. Six patients are well 5 to 17 months after discharge. Seven of the eight deaths were characterized by progressive myocardial failure. One patient died of ventricular fibrillation 18 hours after discontinuation of the left heart bypass. All survivors had significant improvement in ventricular function 12 to 24 hours afer institution of the left heart bypass, which was continued for 16 to 68 hours. These results indicate that early institution of left heart bypass in seriously ill patients can provide satisfactory long-term results.
We compared the clinical, hemodynamic, and morphological findings in 18 young sheep in which porcine valvular bioprosthesis (eight animals) and bovine pericardial bioprostheses (10 animals) were implanted in the tricuspid position. At the time of terminal elective studies (mean of 5.2 +/- 0.2 months after implantation), six animals had ascites, 16 had hepatic congestion, and four had bioprosthetic valvular infection. Hemodynamic studies (n = 10) showed that the tricuspid transvalvular mean diastolic gradients were not different at implantation and at termination of the study (4.7 +/- 0.8 versus 4.9 +/- 0.9 mm Hg); however, tricuspid valve end-diastolic gradients increased from 1.2 +/- 0.6 to 3.9 +/- 0.5 mm Hg (p less than 0.01). Each of the 18 valves had calcific deposits. Quantitative studies revealed that implanted porcine valvular bioprosthesis (n = 7) contained a mean of 323 +/- 165 mg of calcium/gm of dry weight of cuspal tissue, in contrast to 0.2 mg/gm in unimplanted porcine valvular prostheses. Similarly, implanted bovine pericardial bioprostheses (n = 6) contained a mean of 421 +/- 115 mg of calcium/gm of dry weight of cuspal tissue, in contrast to 0.3 mg/gm im unimplanted bovine pericardial bioprostheses. Morphological findings in both types of bioprostheses included calcific deposits, collagen degeneration, leaflet immobilization and retraction, and fibrous sheaths. The latter were more extensive in bovine pericardial bioprostheses than in porcine valvular bioprostheses. We conclude: (1) that the pathological alterations which develop in bovine pericardial bioprostheses are generally similar to those in porcine valvular bioprostheses, but may be more severe; (2) that these alterations lead to physiological and clinical sequelae similar to those of bioprosthetic valvular failure in human subjects; and (3) that young sheep constitute an excellent experimental model for in vivo testing of bioprosthetic cardiac valves.
Seventeen porcine aortic and 10 bovine pericardial bioprosthetic valves were implanted in the tricuspid position in 27 young sheep. Clinical, hemodynamic and morphologic evaluations were performed after a mean of 4.7 +/- 0.3 months (range 3-7 months) after implantation. Eight sheep developed ascites (five with porcine aortic and three with bovine pericardial bioprosthetic valves); all 27 sheep had microscopic evidence of hepatic congestion. Three porcine and three bovine valves became infected. Hemodynamic studies (n = 15) performed immediately after implantation and at the time of terminal elective studies showed that tricuspid valve end-diastolic gradients increased from 0.7 +/- 0.4 mm Hg to 4.5 +/- 0.5 mm Hg (p less than 0.01). All 27 valves had calcific deposits. By quantitative analyses, unimplanted cuspal tissue (n = 9) had 0.6 +/- 0.1 mg/g of calcium/g tissue dry weight; explanted porcine aortic valves (n = 16) had 182 +/- 74 and bovine pericardial valves (n = 6) 421 +/- 115 mg/g of calcium/g of tissue dry weight (NS for porcine aortic vs bovine pericardial valves). Morphologic findings were similar in both porcine aortic and bovine pericardial valves, and consisted of calcific deposits, collagen degeneration, microthrombi and fibrous sheaths. These findings are almost identical to those associated with bioprosthetic valvular failure in humans. In our experimental study, we found no significant differences in the development of calcification in porcine aortic and bovine pericardial bioprosthetic valves.
Myocardial beta-adrenoceptor binding was investigated, with (-)3H dihydroalprenolol as radioligand, in microsomes derived from anterior (ALV) and inferior (ILV) myocardial wall sections of the canine left ventricle. Characterisation of specific binding sites revealed a hierarchy of myocardial beta-adrenoceptor binding with greater binding occurring to the anterior than the inferior wall of the left ventricle, under identical experimental conditions. Equilibrium analysis by Scatchard plots suggested a significant (P less than 0.01) difference in the number of receptors (Bmax ALV = 70 fmol . mg-1 protein vs Bmax ILV = 37 fmol . mg-1 protein) with no alteration in the binding affinity of the receptors (KDALV = 10.1 nmol . litre-1 vs KDILV = 6.7 nmol . litre-1). Such differences in the extent of binding of beta-adrenoreceptors in cardiac muscle may be of physiological and pathological significance and may account for the heterogeneity of regional autonomic responses in the heart.
PEEP is widely accepted as a therapy for some forms of acute respiratory failure (ARF). PEEP increases functional residual capacity (FRC), decreases intrapulmonary shunt fraction, and improves arterial oxygenation. The time required for FRC and arterial oxygen tension (PaO2) to stabilize after an adjustment in the level of PEEP is not clearly established. Therefore, to determine the temporal relationship between PEEP, FRC, and PaO2 after adjusting the level of PEEP, aspiration pneumonitis was produced in swine. The FRC and the PaO2 decreased within seconds after intratracheal instillation of 0.1 N HCl; FRC of all animals was restored to its control value after the application of PEEP, 5 cm H2O, but PaO2 remained low. It was necessary to increase PEEP to 20 cm H2O and FRC to twice the control value to return arterial oxygenation to control levels. After PEEP was applied, an average of 15 sec was required to increase FRC; the less compliant the lung, the more rapid the change. After PEEP was removed, FRC stabilized within an average of 22 sec. When PEEP, 25 cm H2O, was removed, arterial oxygenation decreased suddenly and substantially which suggests that PEEP, especially at higher levels, should not be discontinued, even momentarily, for nonessential maneuvers.
It has been shown experimentally that irreversible brain injury and death may follow after 5-7 min of cerebral ischemia and that even brief periods, 2 min or less, can produce focal damage to the nervous system. All published studies demonstrating a protective effect of barbiturates have been performed in animals. A patient is presented who recovered full neurological function after 13 min of hypovolemic hypotension. This remarkable outcome may have been due to the rapid institution of high-dose barbiturate therapy. The extent to which such therapy affected his outcome is unclear, but does add to the growing body of evidence suggesting a favorable effect from this type of barbiturate therapy.
Significant resistance was encountered when an attempt was made to withdraw a persistently wedged pulmonary artery catheter. A small amount of air was injected into the balloon lumen with great difficulty. This injection freed the catheter which was removed, but produced significant sudden hemoptysis and a pneumothorax. The etiology of this complication and guidelines to avoid it are presented.
Using a specific radioimmunoassay for enzymically inactive creatine kinase (EC 2.7.3.2) B protein (CK-Bi), we studied 139 patients with various malignancies. We found it to be increased in certain adenocarcinomas, including colorectal, lung, and prostate, as has also been reported for enzymically active CK-BB. Of 15 patients with leukemia or lymphomas with active disease, 12 also had increased values for CK-Bi in plasma. In these patients, concentrations of CK-Bi in plasma tended to correlate with disease activity, increasing with aggressive malignancy and decreasing on successful treatment. Thus, measurement of CK-Bi may constitute a sensitive means for detecting malignancy and, in certain subsets of patients, for monitoring therapeutic response.
(25)Mg NMR spectroscopy is applied to a study of magnesium ion interactions with DNA, which is considered as a model for a linear polyelectrolyte. It is demonstrated that the magnesium ion spectrum is complicated by a non-Lorent-zian line shape and is dominated by the effects of chemical exchange with macromolecule binding sites. A distinction is made between specific-site interactions in which the magnesium ion loses a water molecule from the first coordination sphere on binding and those interactions, referred to as territorial binding, in which the ion maintains its first coordination sphere complement of solvent. The first type of site-binding interactions are shown to dominate the magnesium ion NMR spectrum, based on a consideration of the magnitudes of the observed (25)Mg relaxation rates compared with (23)Na relaxation rates, the clear contributions of chemical exchange-limited relaxation, and an ion displacement experiment employing sodium.