Effects of dimethyl sulfoxide on the globally ischemic heart: Possible general relevance to hypothermic organ preservation

Isolated perfused rabbit hearts were made globally ischemic for 2 hr, then reperfused. For 5 min before and after ischemia hearts were perfused with hypothermic (20 or 27 [deg]C), hypoxic, substrate-free cardioplegic solutions, some of which contained 70 mM dimethyl sulfoxide. Postischemic ventricular pressure development, spontaneous heart rate, coronary flow, lactate dehydrogenase release, tissue Ca2+ content, and in vitro mitochondrial oxidative phosphorylation were used to evaluate the protective effects of the various solutions. Aside from the expected observations that cold cardioplegia lessens ischemic damage, we found that dimethyl sulfoxide gave no indication that it exacerbated ischemic damage or lessened the protection afforded by cardioplegia. We also found that, compared to values measured in comparable drug-free treated hearts, dimethyl sulfoxide significantly improved mitochondrial State 3 respiratory rates, respiratory control, and oxidative phosphorylation rates, and essentially prevented mitochondrial changes due to ischemia and reperfusion. We propose that dimethyl sulfoxide may act as a "scavenger" of cytotoxic free radicals, many of which are known to be generated by mitochondria during reoxygenation. Since hypoxia, ischemia, and reoxygenation are common accompaniments of most organ preservation protocols, we suggest that low concentrations of dimethyl sulfoxide might serve as a useful adjunct to organ preservation in the nonfrozen state, when cryoprotective concentrations are not needed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24063/1/0000315.pd

Hemolysis in the Starr-Edwards aortic prostheses

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33972/1/0000244.pd

Absence of detectable xanthine oxidase in human myocardium

The enzyme xanthine oxidase has been implicated as a generator of toxic oxygen metabolites that contribute to ischemic injury. Because substantial species variability has been demonstrated and because there are minimal human data available, the relevance of xanthine oxidase to human heart damage has been in doubt. We report the absence of xanthine oxidase activity in nine human heart biopsy specimens obtained during cardiac surgery, and in two larger samples obtained during heart transplantation. A sensitive radiochemical assay was used to assess enzyme activity. Our findings imply that oxygen free radicals generated by xanthine oxidase are not relevent in terms of human myocardial injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28034/1/0000473.pd

Perioperative management of the patient undergoing automatic internal cardioverter-defibrillator implantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28646/1/0000461.pd

Cardiogenic shock complicating acute myocardial infarction: The use of coronary angioplasty and the integration of the new support devices into patient management

Conventional therapy for cardiogenic shock complicating acute myocardial infarction continues to be associated with a high in-hospital mortality rate. Hemodynamic support with new mechanical devices and emergency coronary revascularization may alter the long-term prognosis for patients with this complication. Between July 1985 and March 1990, 68 patients presented to the University of Michigan with acute myocardial infarction and cardiogenic shock. Interventions performed included thrombolytic therapy (46%), intraaortic balloon pump counterpulsation (70%), cardiac catheterization (86%), coronary angioplasty (73%), emergency coronary artery bypass grafting/ventricular septal defect repair (15%), Hemopump insertion (11%), percutaneous cardiopulmonary support (4%) and ventricular assist device (3%).The 30-day survival rate was significantly better in patients who had successful angioplasty of the infarct-related artery than in patients with failed angioplasty (61% vs. 7%, p = 0.002) or no attempt at angioplasty (61% vs. 14%, p = 0.003). This difference was maintained over the 1-year follow-up period. The only clinical variable that predicted survival was age <65 years.The early use of the new support devices in 10 patients was associated with death in 8 (80%), but this poor outcome may reflect a selection bias for an especially high risk population. Collectively, these recent data continue to suggest that emergency revascularization with angioplasty may reduce the mortality rate, but further study is required to define optimal utilization and integration of new support devices

Evaluation of left ventricular ejection fraction as a measure of pump performance in patients with chronic mitral regurgitation

Left ventricular (LV) ejection fraction may not adequately detect a reduction in LV systolic performance resulting from chronic mitral regurgitation (MR), due to ventricular unloading into the low-impedance left atrium. To determine whether LV ejection fraction sufficiently gauges myocardial function in MR, nine patients were studied using micromanometer-measured LV pressures and biplane cineventriculography before and 1 year after mitral valve surgery. Six control patients were also studied. LV ejection fraction was normal in MR patients, despite an increase in LV end-systolic volume index. LV end-systolic pressure-volume and stress-volume ratios in MR patients were lower than in controls ( P < 0.05 and P < 0.01), suggesting that LV systolic performance fell. One year after mitral valve surgery, LV ejection fraction decreased ( P < 0.05) even though LV end-systolic volume index ( P < 0.05), pressure-volume ( P < 0.05), and stress-volume ratios ( P < 0.01) all improved. Thus, LV ejection fraction inadequately reflected LV systolic function in MR patients before and after mitral valve surgery. Cathet. Cardiovasc. Intervent. 49:290–296, 2000. © 2000 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35248/1/14_ftp.pd

Hemolysis in patients with the cloth-covered aortic valve prosthesis : Changing severity of hemolysis and prediction of anemia

This paper is addressed to two questions: (1) Is there evidence for Increasing hemolysis in patients with a cloth-covered aortic valve prosthesis? (2) Is it possible to predict from the hematocrit, retriculocyte count, serum hemoglobin and serum lactic dehydrogenase (LDH) levels which patients are at risk of anemia? These screening studies were performed in patients attending the postoperative clinic from 1970 to 1973. Patients were classified into anemic and nonanemic groups. LDH values for the anemic group include all yearly values for that patient including preanemia levels. The median LDH levels showed a yearly increase in the anemic group and no change in the nonanemic group (P &lt; 0.005). A subset of these patients had a mean 1 year increase of 3 LDH units for 15 nonanemic patients and 242 units in 17 anemic patients. The reticulocyte levels did not demonstrate any progressive increase in the anemic group. The LDH level was the most useful predictor of future anemia. A value of 250 units predicted anemia on the next yearly visit with 28 percent false positive and 4 percent false negative readings. The reticulocyte count of more than 2.5 percent also placed the patient at greater risk of anemia. A serum hemoglobin level in excess of 40 mg/100 ml was common in the anemic patients and was present in only 3 of 17 nonanemic patients. It is suggested that the serum LDH level should be monitored in all patients with the aortic totally cloth-covered prosthesis. Values in excess of 250 units (four times the upper limit of normal by other LDH methods) or increasing levels, or both, suggest future anemia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22257/1/0000693.pd

Outcome of endocardial resection in 33 patients with coronary artery disease: Correlation with ventricular tachycardia morphology

The results in 33 patients with ventricular tachycardia (VT) treated by endocardial resection were reviewed, with special emphasis on the presence of single or multiple morphologies preoperatively and intraoperatively. Multiple VT morphologies were induced in 16 patients and a single VT morphology was induced in the remaining 17. Intraoperative programmed stimulation failed to induce VT in eight patients and visually-directed endocardial resection was performed. The remaining patients underwent map-guided resection. The surgical success rate did not correlate with any morphologic characteristics of the VT, such as bundle branch block pattern or axis. In addition, concordance of VT morphologies preoperatively and intraoperatively before resection did not correlate with the surgical success rate. However, patients in whom multiple morphologies of VT were induced intraoperatively had a significantly higher success rate (100%) compared with those patients in whom only a single morphology was induced intraoperatively (50%, p &lt; 0.05). Long-term follow-up was maintained in 26 patients. Ventricular tachycardia recurred in two patients and VF recurred in two others who did not have inducible VT 1 week after endocardial resection. In conclusion, neither the preoperative morphologic characteristics of VT nor discordance between the morphologies of VT induced preoperatively and in the operating room influenced the outcome of endocardial resection. However, the surgical success rate is higher when multiple morphologies of VT are inducible in the operating room than when only one VT morphology is inducible.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29715/1/0000049.pd

Natriuresis associated with elevated plasma atrial natriuretic hormone during supraventricular tachycardia

Elevated plasma levels of atrial natriuretic hormone (ANH) have been found in patients during paroxysmal supraventricular tachycardia (SVT) and other clinical syndromes. However, physiologic effects of this endogenous ANH have not been demonstrated. To determine whether the rise in ANH during SVT is associated with either a natriuresis or kalluresis, urine sodium and potassium levels were measured in five patients at baseline and during SVT simulated by rapid atrioventricular pacing. Plasma ANH levels increased from 149 +/- 35 pmol/L at baseline to 387 +/- 31 pmol/L (p = 0.007) during SVT. Plasma vasopressin and renin levels were unchanged. Urine sodium levels increased 49% from 1.54 +/- 0.66 mEq/hr at baseline to 2.29 +/- 0.89 mEq/hr (p = 0.044) during SVT, and urine potassium levels increased 22% from 4.14 +/- 0.10 mEq/hr to 5.04 +/- 1.25 mEq/hr (p = 0.018). Urine sodium and potassium levels returned to baseline values 1 hour after pacing. Thus elevated plasma levels of ANH during SVT are associated with both a natriuresis and kalluresis, which may represent physiologic effects of the endogenously secreted hormone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28078/1/0000523.pd

Incidence, presentation, diagnosis, and management of malfunctioning implantable cardioverter-defibrillator rate-sensing leads

Recognition of tachyarrhythmia by an implantable cardioverter-defibrillator (ICD) requires an intact rate-sensing lead. We retrospectively examined 266 consecutive patients requiring an ICD to characterize the incidence, clinical presentation, diagnosis, and management of a defective rate-sensing lead. To identify clinical parameters that may contribute to lead complications, we also assessed the effects of age, gender, type of rate-sensing lead, manufacturer of the lead, and surgeon. Over a follow-up period of 30 +/- 22 months (mean +/- standard deviation), a defective lead was found in 9 (3.4%) patients, in 9 (1.7%) of 514 leads over a period of 2 to 39 (mean 17 +/- 15) months after implantation. Except for 1 patient, in whom a lead fracture was incidently found during ICD generator replacement, these patients had multiple inappropriate shocks of recent onset. Clinical parameters were not helpful in identifying patients at risk for lead complication. An abnormal beeping signal obtained while the patients performed various maneuvers was helpful in confirming a defect. All of the defective leads were epicardial. These cases were managed by placement of a transvenous endocardial lead.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31233/1/0000136.pd