John H. Kalbfleisch

Myocardial ischemia during cardiovascular surgery as detected by an ST segment trend monitoring system

The incidence of intraoperative myocardial ischemia was determined in 312 patients undergoing cardiovascular surgery using ECG recordings obtained from a prototype system that trends ST segment changes. Prior to cardiopulmonary bypass, ischemic ECG changes were observed in 11.9% of patients, the incidence being lower during coronary artery bypass grafting (CABG) procedures (8.1%) than in patients undergoing repeated CABG (23.5%), valve replacement (25.9%), or concomitant valve replacement and CABG (35.3%). The occurrence of intraoperative myocardial ischemia was statistically greater in patients with a history of hypertension, two or more previous myocardial infarctions, or kidney disease. The incidence of ischemia was also significantly greater in patients with left ventricular end-diastolic pressures of 15 mm Hg or higher at cardiac catheterization. The incidence during induction was significantly reduced by the addition of hypnotics to narcotics, and, during maintenance, by the addition of an inhalational agent. The majority of ischemic events were temporally related to some hemodynamic disturbance, and many coincided with surgical manipulation. The incidence of intraoperative myocardial ischemia was substantially less than that reported in comparable studies. Since the incidence decreased significantly following clinical acceptance of the prototype system, the authors conclude that such capability increases sensitivity to small ST segment changes. This heightened awareness and prompt remedial action reduced the incidence of ischemia during CABG to 6% during the final 2 years of the study.

Response of patients after myocardial infarction to carrying a graded series of weight loads

Cardiovascular responses to carrying graded weight loads of 20 to 50 pounds were determined in 52 patients after myocardial infarction (MI) (greater than or equal to 2 months). Sixty percent of the patients were stopped before completing the heaviest weight load (50 pounds for 2 minutes) because of an increase in diastolic blood pressure (BP) to 120 mm Hg (end point) or arm fatigue. Compared with symptom-limited graded dynamic exercise, peak systolic and diastolic BP were significantly greater (p less than 0.05 and p less than 0.01, respectively) with weight carrying, while peak heart rate, pressure-rate product, ventilation and oxygen consumption were significantly lower (p less than 0.01). Ischemic responses were less frequent with weight carrying. Patients with severely reduced resting left ventricular ejection fraction (LVEF) (less than 35%) tolerated the weight carrying test as well as patients with normal resting LVEFs (greater than 50%). We conclude that (1) ischemic responses occur less frequently while carrying up to 50 pounds for 2 minutes than with symptom-limited dynamic exercise, (2) a significant number of patients have an increase in diastolic BP greater than or equal to 120 mm Hg while carrying objects that weigh 30 to 50 pounds for 2 minutes, and (3) a poor correlation exists between resting LVEF and tolerance for weight carrying.

Circulating basophils in normal subjects and in subjects with hay fever

The relationship of hay fever symptoms and changes in the number of circulating basophils was studied in 12 subjects clinically sensitive only to ragweed and in 10 nonatopic subjects before, during, and after the ragweed season. Total white blood counts, absolute basophil counts, and symptom scores were recorded twice weekly from mid-June through October, 1974, and compared with the ragweed pollen count. The results indicated that the absolute and relative number of basophils were significantly elevated (p less than 0.001) in the hay fever group when symptoms occurred. As the symptom score of the allergic group increased during the ragweed season, the number of basophils also increased, only to decrease to control values when symptoms subsided. The basophil counts of the atopic group were significantly higher than those of the nonatopic group during the control periods. The nonatopic group also showed a significant elevation of basophils during the ragweed season, but to a much lesser extent than the atopic group. It is concluded that: (1) subjects with symptomatic hay fever have a significantly elevated absolute and relative basophil count which correlates with the exacerbation and remission of symptoms; (2) nonatopic subjects also have a small but significant elevation of basophils during the ragweed season; and (3) the elevation of basophils in the atopic group during symptoms is significantly greater than in the nonatopic group during the ragweed season.

Diagnostic precision of echocardiography in mitral valve prolapse

In order to determine the precision with which currently used echocardiographic criteria can be applied for the diagnosis of mitral valve prolapse, three independent observers (A, B, and C) blindly analyzed the separate M-mode and two-dimensional echocardiograms of 50 patients, 27 of whom had previously been identified clinically as having echocardiographic evidence of prolapse. Observer As intraobserver repeatability for M-mode echocardiography was 92%, Observer Bs was 84%, and Observer Cs was 90%. For two-dimensional echocardiography, Observer As intraobserver repeatability was 98%, Observer Bs was 80%, and Observer Cs was 82%. We believe that the variability in intraobserver repeatability is related to the frequency with which individual observers diagnosed prolapse. The interobserver repeatability for M-mode echocardiography for Observer A versus B was 64%, for Observer A versus C it was 80%, and for Observer B versus C it was 66%. The interobserver repeatability for two-dimensional echocardiography for Observer A versus B was 54%, for Observer A versus C it was 70%, and for Observer B versus C it was 52%. There was no significant difference between the inter- and intraobserver variability of M-mode versus two-dimensional echocardiography. Review of cases in which readings were discrepant revealed that these cases usually had relatively mild changes. Clinicians should be aware of the inherent variability of echocardiographic interpretation when they make a diagnosis of mitral valve prolapse.

Effect of central air conditioning and meteorologic factors on indoor spore counts

We have studied the effect of residential central air conditioning on indoor spore counts. The air of 6 pairs of homes (air-conditioned and non-air-conditioned) was sampled volumetrically 4 times daily for 3 consecutive days at 2-hr intervals in the kitchens, bedrooms, and basements with an Anderson sampler. Nearly simultaneous samples were taken outdoors at the same intervals. The total spore count was significantly lower (p less than 0.05) in the kitchens and bedrooms of air-conditined as compared to non-air-conditioned homes. Logarithmic conversion of the total spore count showed significant reduction in all indoor locations of air-conditioned homes. Multiple regression analysis revealed the lower relative humidity of air-conditioned homes to be associated with the lower spore counts. There was no difference in the percent concentration of the major genera within both types of homes. Since reducing the influx of outdoor spores decreases the total spore count without altering the relative concentration of the genera whereas filtration preferentially removes the larger spores, we conclude that the major mechanism in reducing spore counts in air-conditioned homes is the closed windows, although the lower relative humidity and perhaps filtration are also associated with lower spore counts.

Lipid peroxidation caused by hyperthermic perfusion of rat liver

The data presented support the premise that hyperthermia-induced hepatocellular injury is the end result of lipid peroxidation. Evidence for lipid peroxidation is the formation of diene conjugates and the decrease in microsomal P450 and glucose-6-phosphatase activity during hyperthermic liver perfusion.

Evaluation of a prolonged infusion of recombinant tissue-type plasminogen activator (Duteplase) in preventing reocclusion following successful thrombolysis in acute myocardial infarction☆

The hypothesis that an infusion of recombinant tissue-type plasminogen activator (rt-PA) maintained for up to 24 hours could prevent reocclusion after early coronary patency had been established was evaluated in patients with acute myocardial infarction. The rt-PA studied was an investigational double chain rt-PA (Duteplase, Burroughs Wellcome Co.), administered according to body weight. Coronary patency was documented in 139 of 213 patients who had 90-minute angiograms recorded after an initial lytic dose of rt-PA. In these responders a further 90-minute infusion at one third the initial lytic dose was given before assignment to 1 of 4 maintenance dose rates (0.012, 0.024, 0.036, 0.048 MIU/kg/hour) which were continued for the subsequent 9 to 21 hours. The principal end point was the status of the infarct-related coronary artery 12 to 24 hours after the start of therapy, and before termination of rt-PA, in patients with initially patent vessels at 90 minutes. Of the 103 responders with repeat angiograms after a 9 to 21 hour maintenance infusion of rt-PA, a total of 17 (16.5%) patients reoccluded across all doses administered. There was no significant relationship between the maintenance dose rate and the incidence of reocclusion. However, there was strong association between total dose of rt-PA administered and the incidence (16%) of serious or life-threatening bleeding exclusive of surgery. Other factors associated with serious bleeding included low body weight, female gender, and total duration of rt-PA infusion. Reocclusion was independent of the 90-minute Thrombolysis in Myocardial Infarction trial perfusion grade and diameter of infarct vessel. Rethrombosis after establishment of early patency after rt-PA remains a significant problem that is unaffected by sustained rt-PA infusion in doses that can be tolerated.

Existence of basophil chemotaxis in subjects with hay fever

From an earlier study we proposed that the relative peripheral basophilia of subjects with symptomatic hay fever might be associated with a basophil chemotactic factor in the serum. Six subjects with symptomatic hay fever and six nonallergic subjects were tested for basophil chemotaxis (BC) weekly during and after the hay fever season. Cells of the allergic subjects with autologous serum showed significantly more BC than with control serum during the symptomatic weeks. After they hay fever season there was no difference in BC between the allergic and nonallergic groups. We conclude that there is a BC factor(s) in the serum of symptomatic subjects with hay fever which requires basophils from symptomatic subjects to be demonstrable.

Progression of changes in gastric emptying of hypertonic liquids after proximal gastric vagotomy. An experimental study.

Gastric emptying rates of hypertonic (10%) dextrose liquid meals were studied in five dogs before, and 3, 6, and 12 months after proximal gastric vagotomy (PGV) without drainage. The purpose of this study was to determine if operation-related changes in emptying rates normalized or became more disparate during the year after PGV. An increased rate of emptying during the first 5 min after ingestion was seen at 3 months after PGV, which significantly increased (P<0.025) after 6 and 12 months. The remainder of the meal after PGV emptied at a regulated exponential rate unchanged throughout the postoperative year from its preoperative rate. Total volumes of gastric aspirate at four intervals after meal ingestion did not significantly change across the four test periods in respect to endogenous secretion or pH acidity.

Concomitant Therapy With Labetalol and Hydrochlorothiazide in Moderate to Moderately Severe Essential Hypertension

Labetalol is a competitive, nonselective antagonist of both beta1 and beta2 adrenoceptors. It has been suggested that labetalol reduces blood pressure (BP) predominately by decreasing peripheral vascular resistance while maintaining cardiac output. We conducted a double‐blind, randomized study to assess the antihypertensive effect of labetalol in patients with a standing diastolic blood pressure (SDBP) between 105 and 119 mm Hg. The study consisted of three separate phases in succession. Phase I was a single‐blind, placebo washout phase, two to four weeks in length. Those patients with a SDBP 105 mm Hg at the end of phase I entered phase II, in which they were administered labetalol in a forced titration of 100 mg bid to 400 mg bid. Those with a SDBP 90 mm Hg on the 400 mg bid regimen for two weeks were maintained on labetalol alone (N = 8). Those patients whose BP was not controlled (SDBP 90 mm Hg, N = 15) were randomized in a double‐blind fashion to receive either hydrochlorothiazide (HCTZ) or placebo in addition to labetalol for the next five weeks. Eight of the 15 patients received HCTZ and seven received placebo. The BPs at baseline and at the end of phase II were similar in the two groups. With the addition of HCTZ, the standing BP decreased (P < .01) from 146/102 ± (7/4) mm Hg to 125/89 ± (3/3) mm Hg and supine BP decreased (P < .01) from 151/101 ± (5/5) mm Hg to 136/90 ± (3/3) mm Hg (X̄ ± SEM). Placebo had no significant effect on BP. The SDBP was normalized (< 90 mm Hg) in four of the eight patients who received HCTZ as compared with one of seven who received placebo. Heart rate decreased significantly (P < .05) with labetalol and the addition of HCTZ had no effect on heart rate. We conclude that labetalol alone can normalize BP in approximately one third of hypertensive patients and that the addition of a diuretic can normalize it in another one third without significant side effects.