Myoglobin levels at 12 hours identify patients at low risk for 30-day mortality after thrombolysis in acute myocardial infarction: a Thrombolysis in Myocardial Infarction 10B substudy

OBJECTIVE

We sought to identify, by use of serum cardiac markers, patients at low risk for 30-day mortality after ST-segment elevation myocardial infarction.

BACKGROUND

Baseline cardiac markers are currently used to identify patients at increased risk for short-term events. We hypothesized that serum markers measured after treatment could identify patients at low risk for 30-day mortality.

METHODS

A total of 839 patients from the Thrombolysis in Myocardial Infarction (TIMI) 10B study had myoglobin, cardiac-specific troponin-I, creatine kinase (CK)-MB measurements at the following time points; baseline, 90 minutes, and 3 and 12 hours after thrombolysis. By use of receiver operating characteristic analysis, thresholds were derived to predict 30-day mortality with at least 95% negative predictive value.

RESULTS

Ninety minutes after thrombolysis myoglobin was superior to troponin-I or CK-MB in identifying patients at low risk for mortality. The 30-day mortality for 12-hour myoglobin < or = 239 ng/mL was 1.4% compared with 9.1% for levels > 239 ng/mL (P < .001). For 12-hour troponin-I (threshold 81.5 ng/mL), mortality was 1.9% versus 6.6% (P = .001) if above threshold; similarly for CK-MB at 12 hours (threshold 191 ng/mL) it was 3.3% versus 7.9% (P = .02). Multivariate analysis of baseline and posttreatment cardiac markers, age, sex, infarct artery location, and 90-minute TIMI flow grade identified only 12-hour myoglobin among the cardiac markers as independently predicting a low 30-day mortality (odds ratio 0.11, 95% confidence interval 0.02-0.50, P < .004).

CONCLUSION

Serum cardiac markers can identify greater than two thirds of patients at low risk for 30-day mortality. A low 12-hour myoglobin level (< or = 239 ng/mL in this substudy) identifies such patients at low risk and could potentially assist in early risk stratification and triage after ST-segment elevation myocardial infarction.

Low-dose enoximone improves exercise capacity in chronic heart failure. Enoximone Study Group

OBJECTIVES

This study was designed to evaluate the effects of low-dose enoximone on exercise capacity.

BACKGROUND

At higher doses the phosphodiesterase inhibitor, enoximone, has been shown to increase exercise capacity and decrease symptoms in heart failure patients but also to increase mortality. The effects of lower doses of enoximone on exercise capacity and adverse events have not been evaluated.

METHODS

This is a prospective, double-blind, placebo-controlled, multicenter trial (nine U.S. centers) conducted in 105 patients with New York Heart Association class II to III, ischemic or nonischemic chronic heart failure (CHF). Patients were randomized to placebo or enoximone at 25 or 50 mg orally three times a day. Treadmill maximal exercise testing was done at baseline and after 4, 8 and 12 weeks of treatment, using a modified Naughton protocol. Patients were also evaluated for changes in quality of life and for increased arrhythmias by Holter monitoring.

RESULTS

By the protocol-specified method of statistical analysis (the last observation carried-forward method), enoximone at 50 mg three times a day improved exercise capacity by 117 s at 12 weeks (p = 0.003). Enoximone at 25 mg three times a day also improved exercise capacity at 12 weeks by 115 s (p = 0.013). No increases in ventricular arrhythmias were noted. There were four deaths in the placebo group and 2 and 0 deaths in the enoximone 25 mg three times a day and enoximone 50 mg three times a day groups, respectively. Effects on degree of dyspnea and patient and physician assessments of clinical status favored the enoximone groups.

CONCLUSIONS

Twelve weeks of treatment with low-dose enoximone improves exercise capacity in patients with CHF, without increasing adverse events.

Cardiac cephalgia: a treatable form of exertional headache

We report two patients with exertional headaches beginning with vigorous exercise and relieved by rest. Neurologic evaluation and neuroimaging were normal in both. During exercise stress testing, the onset of the patients' typical headaches correlated with ECG changes indicative of myocardial ischemia. In both patients coronary angiography revealed three-vessel disease, and myocardial revascularization procedures were followed by complete resolution of headaches. Based on these patients, and a review of prior similar reports, we conclude that myocardial ischemia is a rare and treatable cause of exertional headache. Accurate diagnosis is critical to controlling headaches and preventing myocardial infarction.

Emotional expression and physical health: revising traumatic memories or fostering self-regulation?

Health benefits derived from personal trauma disclosure are well established. This study examined whether disclosing emotions generated by imaginative immersion in a novel traumatic event would similarly enhance health and adjustment. College women, preselected for trauma presence, were randomly assigned to write about real traumas, imaginary traumas, or trivial events. Yoked real-trauma and imaginary-trauma participants wrote about real-trauma participants' experiences. Imaginary-trauma participants were significantly less depressed than real-trauma participants at immediate posttest, but they were similarly angry, fearful, and happy. Compared with control group participants, both trauma groups made significantly fewer illness visits at 1-month follow-up; however, real-trauma participants reported more fatigue and avoidance than did the other groups. Imaginary-trauma group effects could reflect catharsis, emotional regulation, or construction of resilient possible selves.

Emotional expression and physical health: revising traumatic memories or fostering self-regulation?

Health benefits derived from personal trauma disclosure are well established. This study examined whether disclosing emotions generated by imaginative immersion in a novel traumatic event would similarly enhance health and adjustment. College women, preselected for trauma presence, were randomly assigned to write about real traumas, imaginary traumas, or trivial events. Yoked real-trauma and imaginary-trauma participants wrote about real-trauma participants' experiences. Imaginary-trauma participants were significantly less depressed than real-trauma participants at immediate posttest, but they were similarly angry, fearful, and happy. Compared with control group participants, both trauma groups made significantly fewer illness visits at 1-month follow-up; however, real-trauma participants reported more fatigue and avoidance than did the other groups. Imaginary-trauma group effects could reflect catharsis, emotional regulation, or construction of resilient possible selves.

Dobutamine echocardiography and resting-redistribution thallium-201 scintigraphy predicts recovery of hibernating myocardium after coronary revascularization

The value of dobutamine echocardiography and resting thallium-201 scintigraphy to predict reversal of regional left ventricular wall motion dysfunction after revascularization in patients with chronic coronary artery disease was assessed. Improvement in wall motion during dobutamine echocardiography and normal or mildly decreased uptake on thallium-201 scanning are strong predictors of reversible left ventricular dysfunction. Dobutamine echocardiography and resting thallium-201 scanning are simple and safe methods of assessing hibernating myocardium.

Should all patients undergoing cardiac catheterization or percutaneous transluminal coronary angioplasty receive oxygen?

BACKGROUND

Supplemental oxygen is routinely administered to patients with acute coronary syndromes. The risk of significant morbidity during cardiac catheterization or coronary angioplasty has been well described; however, to our knowledge, the need for routine oxygen supplementation in these patients has not been investigated.

METHODS

In phase 1, we prospectively studied 142 patients undergoing diagnostic cardiac catheterization (n = 94) or percutaneous transluminal coronary angioplasty (PTCA) (n = 48) to determine the incidence of procedure-related hypoxemia (pulse oximetry derived oxygen saturation [SpO2] < 90 percent of > 1 min duration) while breathing room air (RA). In phase 2, 134 patients undergoing diagnostic cardiac catheterization (n = 78) or PTCA (n = 56) were randomly allocated to breathe either RA or supplemental oxygen (O2, 6 L/min by nasal cannula) to determine the effect of oxygen administration on procedure-related hypoxemia. Oximetry results were compared with pertinent clinical and procedural data that might predispose patients to develop hypoxemia.

RESULTS

Phase 1--Moderate to severe hypoxemia occurred in 36 percent (34/94) of patients undergoing diagnostic catheterization and in 56 percent (27/48) of patients undergoing PTCA. In the diagnostic catheterization group, there were a total of 25 episodes of moderate hypoxemia (SpO2 85 to 89 percent) lasting 4.0 +/- 4.3 min and 11 episodes of severe hypoxemia (SpO2 < 85 percent) of greater duration, 11.7 +/- 7.5 min (p < 0.008). In the PTCA group, there were 24 episodes of moderate hypoxemia and six episodes of severe hypoxemia lasting 4.8 +/- 4.3 min and 8.2 +/- 3.8 min, respectively. A history of chronic lung disease was associated with hypoxemia (p < 0.05) in the diagnostic group. In addition, 11 patients undergoing diagnostic catheterization who had baseline SpO2 < 95 percent all developed hypoxemia during the procedure. In this subset of patients, there was a higher incidence of cigarette smoking (p = 0.02), chronic lung disease (p = 0.04), higher left ventricular diastolic pressure (p = 0.02), and lower ejection fraction (p = 0.002) when compared with the 83 remaining patients undergoing diagnostic catheterization with a baseline SpO2 > 95 percent. Phase 2--Oxygen therapy was associated with a reduction in the incidence of hypoxemia from 42 percent to 5 percent (RA vs O2, p < 0.001) in the diagnostic catheterization group and 39 percent to 11 percent (RA vs O2, p < 0.03) in the PTCA group.

CONCLUSIONS

Significant hypoxemia is a common finding among patients undergoing cardiac catheterization or angioplasty despite the absence of predictive risk factors. Severe and prolonged hypoxemic episodes occurred in 10 percent (14/142, phase 1) of patients breathing room air. Patients undergoing diagnostic catheterization with history of chronic lung disease or a baseline SpO2 < 95 percent are at high risk to develop moderate-severe hypoxemia. Oxygen therapy significantly reduced the incidence and severity of procedure-induced hypoxemia in both groups. Our data support the use of both pulse oximetry and oxygen supplementation in patients undergoing cardiac catheterization and PTCA.

Potentially misleading bone scan findings in patients with hepatoblastoma

Eleven patients who underwent nuclear medicine bone scanning were reviewed to determine the incidence of bone scan abnormalities associated with hepatoblastoma. Of these, six patients had abnormal bone scan findings--four with focal involvement. Correlating plain radiographs and/or follow-up nuclear bone scans were available for three of these four. All plain films indicated the presence of osteoporosis. Follow-up scans showed improvement or resolution of abnormalities. None of the patients had documented metastatic bone disease. While there has been no prior reported association, the authors attribute the abnormal bone scan findings to a paraneoplastic syndrome of osteoporosis associated with this primary tumor. They conclude that bone scanning is not routinely indicated in the initial diagnostic staging of hepatoblastoma.

Spontaneous coronary dissection treated with directional coronary atherectomy

We report a case of spontaneous coronary dissection occurring in a middle aged male which was treated with thrombolytic therapy and directional coronary atherectomy. This technique provides a new option for treating this entity in the cardiac catheterization laboratory.

Emotional disclosure about traumas and its relation to health: effects of previous disclosure and trauma severity

This study sought to replicate previous findings that disclosing traumas improves physical health and to compare the effects of revealing previously disclosed versus undisclosed traumas. According to inhibition theory, reporting about undisclosed traumas should produce greater health benefits. Sixty healthy undergraduates wrote about undisclosed traumas, previously disclosed traumas, or trivial events. Contrary to expectations, there were no significant between-groups differences on longer term health utilization and physical symptom measures. However, Ss who disclosed more severe traumas reported fewer physical symptoms in the months following the study, compared with low-severity trauma Ss, and tended to report fewer symptoms than control Ss. Results suggest that health benefits occur when severe traumas are disclosed, regardless of whether previous disclosure has occurred.

Magnetic resonance imaging of suspected atrial tumors

Two-dimensional echocardiography has become the standard technique for evaluation of cardiac and paracardiac mass lesions. We have used magnetic resonance imaging (MRI) as an independent assessment of cardiac-associated masses in patients with echocardiograms demonstrating sessile atrial tumors. MRI was performed in seven patients, ages 33 to 84, whose echocardiographic diagnoses included left atrial mass (five), right atrial mass (one), and interatrial mass (one). In four of the patients with a diagnosis of left atrial mass, MRI showed extracardiac compression of the atrium, simulating a tumor (hiatal hernia, tortuous descending aorta, bronchogenic cyst). MRI was entirely normal in one patient with an apparent left atrial mass. MRI elucidated extension of an extracavitary mass into the interatrial septum in two patients. One of these patients with an echocardiographic right atrial mass had extension of a lipoma into the interatrial septum without atrial tumor. MRI confirmed the echocardiographic diagnosis of an interatrial mass in the other patient. We conclude that MRI, because of its ability to define anatomic relationships and tissue characteristics, is a powerful noninvasive tool for evaluating suspected cardiac mass lesions. Although echocardiography remains the primary screening test for the detection of cardiac masses, MRI is a more specific modality for precise diagnosis. Correct MRI interpretation may obviate the need for invasive studies or surgery.

One-year results of the Thrombolysis in Myocardial Infarction investigation (TIMI) Phase II Trial

BACKGROUND

The Thrombolysis in Myocardial Infarction (TIMI) Phase II Trial randomized 3,339 patients to either an invasive (INV, n = 1,681) or a conservative (CON, n = 1,658) strategy after intravenous recombinant tissue-type plasminogen activator (rt-PA) for acute myocardial infarction.

METHODS AND RESULTS

The patients assigned to the INV strategy routinely underwent cardiac catheterization, and when anatomically appropriate, percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting 18-48 hours after infarction. CON patients had these procedures only in response to the occurrence of spontaneous or provoked ischemia. One-year follow-up data are available in 3,316 patients (99.3%). The primary trial end point, death and nonfatal reinfarction, occurred in 14.7% of INV patients and in 15.2% of CON patients (p = NS). When analyzed individually, there was no difference (p = NS) in death (INV, 6.9%; CON, 7.4%) or recurrent infarction (INV, 9.4%; CON, 9.8%) between the two groups. Anginal status at 1 year was also similar. Cardiac catheterization and PTCA were performed more often in INV (98.0% and 61.2%, respectively) compared with CON (45.2% and 20.5%, respectively) patients. At 1 year, the cumulative number of patients who underwent coronary bypass surgery (INV, 17.5%; CON, 17.3%) was similar in the two groups.

CONCLUSIONS

The INV and CON strategies resulted in similar favorable outcomes at 1 year of follow-up. In particular, the rates of mortality and reinfarction were not different and were impressively low in both groups. One possible advantage of the INV strategy was detected in subgroup analyses. In patients with a history of myocardial infarction, the data are suggestive that 1-year mortality was lower in INV patients (10.3%) than in CON patients (17.0%) (p = 0.03).

Coronary angioplasty performed within the thrombolysis in Myocardial Infarction II study

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) of the infarct-related artery was performed within 42 days of recombinant tissue-type plasminogen activator (rt-PA) administration in 1,414 of the 3,534 patients who participated in the Thrombolysis In Myocardial Infarction (TIMI) II study. Primary angiographic success was obtained in 88.7%, with bypass surgery within 24 hours in 3.3% and death within 24 hours in 0.7% of patients. By 1 year, 25.1% of the 1,414 patients had sustained one or more adverse outcomes including death (3.6%), reinfarction (8.4%), or the need for further revascularization (20%).

METHODS AND RESULTS

Despite these generally favorable results, multivariate testing identified several anatomic and clinical subgroups as having an increased risk ratio (RR) for adverse outcome: Unsuccessful PTCA was more common in patients undergoing protocol-assigned PTCA within 2 hours of rt-PA administration (RR, 2.7; p less than 0.001) and in patients over age 70 years (RR, 1.7; p = 0.034). The need for further revascularization within 1 year was increased in the 30.4% of patients with multivessel disease (RR, 2.5; p less than 0.001), patients with prior angina (RR, 1.4; p less than 0.006), or those undergoing ischemia-driven PTCA within 15 hours of rt-PA administration (RR, 1.7; p = 0.022). The risk of death or recurrent infarction within 1 year was increased by the presence of multivessel disease (RR, 1.6; p = 0.007) or prior angina (RR, 1.5; p = 0.014).

CONCLUSIONS

These observations do not necessarily apply to patients undergoing primary PTCA (or PTCA after other thrombolytic agents); however, they do offer a unique yardstick against which to evaluate the results of PTCA in myocardial infarction.

Emotional disclosure about traumas and its relation to health: Effects of previous disclosure and trauma severity

This study sought to replicate previous findings that disclosing traumas improves physical health and to compare the effects of revealing previously disclosed versus undisclosed traumas. According to inhibition theory, reporting about undisclosed traumas should produce greater health benefits. Sixty healthy undergraduates wrote about undisclosed traumas, previously disclosed traumas, or trivial events. Contrary to expectations, there were no significant between-groups differences on longer term health utilization and physical symptom measures. However, Ss who disclosed more severe traumas reported fewer physical symptoms in the months following the study, compared with low-severity trauma Ss, and tended to report fewer symptoms than control Ss. Results suggest that health benefits occur when severe traumas are disclosed, regardless of whether previous disclosure has occurred.

Self-report, situation-specific coping questionnaires: what are they measuring?

Self-report, situation-specific assessments of coping, such as the Ways of Coping Scale (WOC), have been used frequently in recent years. Several potential issues in the development and use of these questionnaires have been identified, including the applicability of coping items to different kinds of stressful events, the definition of the period for which Ss report coping efforts, and the meaning of the "extent" response key that is used for reporting coping items. In this study, 91 college students completed the WOC and were then interviewed about their responses; interview questions were focused on the 3 issues stated above. The hypothesized concerns about the WOC were supported. Many of the coping items were not applicable to certain kinds of stressful events. Also, how the coping report period was defined varied across Ss and the way in which the extent response key was interpreted differed across both Ss and WOC items.

Self-report, situation-specific coping questionnaires: What are they measuring?

Self-report, situation-specific assessments of coping, such as the Ways of Coping Scale (WOC), have been used frequently in recent years. Several potential issues in the development and use of these questionnaires have been identified, including the applicability of coping items to different kinds of stressful events, the definition of the period for which Ss report coping efforts, and the meaning of the "extent" response key that is used for reporting coping items. In this study, 91 college students completed the WOC and were then interviewed about their responses; interview questions were focused on the 3 issues stated above. The hypothesized concerns about the WOC were supported. Many of the coping items were not applicable to certain kinds of stressful events. Also, how the coping report period was defined varied across Ss and the way in which the extent response key was interpreted differed across both Ss and WOC items.

Congenital anomalies of the coronary arteries. Classification and significance

An understanding of the anomalies of the coronary arteries is imperative for physicians dealing with diagnosis and treatment of coronary artery disease. Although not as common as acquired coronary artery disease, congenital coronary anomalies contribute to significant morbidity and mortality. In addition, they may present difficulties for the angiographer at the time of catheterization, as well as a challenge for the radiologist in interpretation. To facilitate a better understanding of these anomalies, a new classification is presented, together with illustrations and discussion of the clinical significance.

Late systemic-allergic reactions to inhalant allergen immunotherapy

Late systemic-allergic reactions (defined as occurring between 30 minutes and 6 hours after injection) to inhalant allergen immunotherapy were prospectively studied in four allergy treatment centers; 35,674 injections were administered to 712 patients. Twenty-nine patients (4% of all patients) experienced 33 late reactions. Fifty-six injections (0.16% of all injections) were associated with the 33 late reactions. The most common clinical manifestation of a late reaction was urticaria. However, objective respiratory airway involvement, as manifested by wheezing and/or stridor, occurred in 10 (27%) of the late reactions. Delayed reactions involving wheezing and/or stridor were only related to injections from maintenance vials, and all these more severe reactions occurred no later than 60 minutes after injection. We conclude that late systemic-allergic reactions account for a significant percent of the total number of systemic-allergic reactions to inhalant allergen immunotherapy. It is our belief that a 60-minute postinjection waiting period for injections administered from maintenance vials of extract would enhance the safety of inhalant allergen immunotherapy.

Cigarette use among Hispanic and non-Hispanic white school children, Albuquerque, New Mexico

We conducted a survey of cigarette usage among Hispanic and non-Hispanic White school children in Albuquerque, New Mexico. The distributions of current, experimental, and never smokers were similar in the two groups. Among smokers, the average weekly cigarette consumption was 19 for Hispanic White males, 14 for non-Hispanic White males, 16 for non-Hispanic White females, and nine for Hispanic White females. Educational programs are needed to maintain the low-risk status of Southwestern Hispanics for cigarette-related diseases.

Impaired coronary vasodilator responsiveness as a cause of lactate production during pacing-induced ischemia in patients with angina pectoris and normal coronary arteries

Subgroups of patients with angina pectoris and normal coronary arteries are known to have pacing-induced lactate production and, therefore, myocardial ischemia. To examine the mechanism of this pacing-induced ischemia, the effect of incremental atrial pacing on coronary blood flow and metabolism was studied in 27 patients with angina and normal coronary arteries. Seventeen patients continued to exhibit normal lactate extraction even at heart rates up to 160 beats/min (Group 1), whereas in 10 patients (Group 2) lactate extraction changed to production at the highest pacing rate. Coronary blood flow increased in Group 1 patients by 18, 41 and 75%, respectively, as heart rate was increased by 20 beat/min increments from 100 to 160 beats/min. In contrast, coronary blood flow increased by only 8, 7 and 14%, at the three respective pacing rates in Group 2. Between the heart rates of 100 and 160 beats/min, coronary vascular resistance decreased 32% in Group 1 patients but was unchanged in Group 2 patients. There was no significant change in the ratio of myocardial O2 consumption/rate-pressure product in Group 1 patients, but this ratio decreased from 0.91 +/- 0.26 ml O2 X min-1 X (mm Hg X beats/min)-1 to 0.53 +/- 0.11 (p less than 0.05) in Group 2 patients as heart rate increased from baseline to 160 beats/min. Thus, patients with angina and normal coronary arteries who develop ischemia with pacing have a decreased coronary vasodilator response that interferes with their ability to increase myocardial oxygen supply to match the higher demand.

Late and immediate systemic-allergic reactions to inhalant allergen immunotherapy

Systemic-allergic reactions to allergen immunotherapy were prospectively studied in four allergy treatment centers to assess frequency and specific attributes of these episodes relative to several variables. A total of 20,588 extract injections were administered to 628 patients. Forty-two patients experienced a systemic reaction (7%). Fifty-two systemic reactions occurred in total. Eight patients accounted for 18 of the reactions. Late systemic reactions, occurring from 35 minutes to 6 hours after injection, accounted for 38% of all reactions. Extracts containing only pollen antigens were more commonly associated with immediate and late systemic reactions relative to other extracts (p less than 0.001 and p less than 0.01, respectively). There were no significant reaction-rate differences whether immunotherapy was at maintenance or increasing doses or if the time of injection was during a pollinating or nonpollinating season. The most common clinical manifestations of the systemic reactions were generalized pruritus and urticaria. We conclude that patients receiving extracts containing only pollen antigens have increased systemic-allergic reaction rates. A subgroup of patients are at risk for recurrent reactions. Finally, late systemic reactions to immunotherapy are not rare events and pose a definite risk to the individual patient.

Platelet hyperactivity in acute myocardial infarction in man--effects of prostacyclin

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore, an understanding of factors which impact on platelet performance is important. The present study was undertaken 1. to characterize during evolving myocardial infarction (MI) platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and 2. to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving MI were studied. 22 patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 minutes. In 15 of these patients, who had an anterior MI, transcardiac platelet function and response to PGI2 were studied. The results are as follows: Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, are elevated three and ten fold. 6-keto-prostaglandin F1 alpha, the stable end product of PGI2, is less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets, circulating during evolving MI ("ischemic platelets") are hyperaggregable in response to adenosine diphosphate and relatively resistent to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic adenosine monophosphate and the cAMP response to PGI2 are diminished. The platelet hyper-reactivity is most intense early during infarct evolution and decreases with time. Transcardiac measurements indicate that thromboxane is produced across the ischemic/infarcting compartment in ten of 15 patients with anterior MI. The antiplatelet effect of PGI2 is greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving MI characterized by a pro-aggregatory environment, heightened platelet re-activity, both in the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequence of the data are that the infarct patient in the acute phase may benefit from platelet function suppression and requires significantly greater doses of prostacyclin than normal subjects. The data also suggest future directions for therapeutic manipulation of platelet hyper-reactivity in the setting of acute myocardial ischemia.

Systemic and transcardiac platelet activity in acute myocardial infarction in man: resistance to prostacyclin

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore an understanding of factors that influence platelet performance is important. This study was undertaken (1) to characterize during evolving myocardial infarction platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and (2) to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving myocardial infarction were studied. Twenty-two patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 min. In 15 patients with anterior myocardial infarction, transcardiac platelet function and response to PGI2 were studied. Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, were elevated three- and 10-fold. 6-Keto-prostaglandin F 1 alpha, the stable end product of PGI2, was less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets circulating during evolving myocardial infarction ("ischemic platelets") were hyperaggregable in response to ADP and relatively resistant to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic AMP and the cyclic AMP response to PGI2 were diminished. The platelet hyperreactivity, expressed by plasma beta-TG, platelet aggregation, and PGI2-induced inhibition of aggregation, was most intense early during infarct evolution and decreased with time. The increased platelet performance resulted in "platelet fatigue," indicated by decreased contents of beta-TG of the ischemic platelet and decreased TxA2 production in response to collagen. However, the ischemic platelet produced twice normal TxA2 in response to arachidonic acid (stimulus and substrate), demonstrating a heightened metabolic capacity. TxA2 was produced across the ischemic/infarcting compartment in 10 of 15 patients with anterior myocardial infarction. The antiplatelet effect of PGI2 was greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving myocardial infarction, characterized by a proaggregatory environment, heightened platelet reactivity in both the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequences of the data are that the patient in the acute phase of myocardial infarction may benefit from suppression of platelet function and requires significantly greater doses of PGI2 than normal subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Cardiac tamponade in dogs with normal coronary arteries. I. Effect of changing intravascular volume on hemodynamics and myocardial blood flow

Intravascular volume expansion has been shown to improve cardiac output in experimental cardiac tamponade. To determine the limitations of intravascular volume manipulation, acute tamponade was created in 20 anesthetized, spontaneously breathing dogs. The intrapericardial volume causing tamponade was determined for each animal, and kept constant. Hemodynamics were recorded with and without tamponade at multiple levels of intravascular volume. During cardiac tamponade, intravascular volume expansion increased cardiac output only in animals which were initially volume-depleted. Volume expansion of normovolemic or hypervolemic animals caused minimal changes in cardiac output, but increased atrial and aortic pressures. Intravascular volume depletion of the normovolemic animal caused a significant decline in cardiac output, in contrast to the trend towards an increased output following phlebotomy of the volume-expanded animals. In general, the benefit of intravascular volume expansion during cardiac tamponade could only be demonstrated when atrial pressures were below 12 mm Hg.

Cardiac tamponade in dogs with normal coronary arteries. II. Myocardial flow and metabolism with moderate and severe hemodynamic impairment

To determine the effects of cardiac tamponade on myocardial blood flow and its distribution, dogs were prepared with indwelling pericardial catheters. Hemodynamic, myocardial blood flow, and myocardial metabolic data were collected in 5 closed-chest, spontaneously breathing animals with normal blood volumes and hemoglobin concentrations and 6 with acute anemia. Instillation of an average of 89.0 +/- 14.9 ml of modified Normosol into the pericardial space in dogs with normal hemoglobin levels produced mild tamponade with a modest decline in aortic pressure (119.5 +/- 14.3 to 96.8 +/- 12.1 mm Hg) and significant rises in left and right atrial and pericardial pressures to 7-8 mm Hg. Increasing the pericardial volume to 124.0 +/- 13.6 ml produced hypotension (mean aortic pressure 86.2 +/- 10.5 mm Hg) and rises in the left and right ventricular filling pressures and pericardial pressure to 10-11 mm Hg. Total myocardial blood flow fell from 1.19 +/- 0.18 to 0.73 +/- 0.17 ml/min/g (p less than 0.02) during mild tamponade, and fell further to 0.56 +/- 0.17 ml/min/g (p less than 0.05) with more severe tamponade. Despite these declines, the left ventricular wall inner/outer flow ratio and left ventricular flow as a proportion of total cardiac output were unchanged. In dogs with anemia more severe tamponade was created, with consequently more marked hemodynamic abnormalities. However, the relative changes in myocardial blood flow and inner/outer flow ratio were similar. Myocardial metabolic parameters could be evaluated only in the dogs with less severe tamponade.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and hemodynamic correlation in patients with pericardial effusion and swinging heart by echocardiography

The clinical and hemodynamic findings in 13 consecutive patients with "swinging heart" on M-mode echocardiography were analyzed. In these patients the anterior right ventricular and posterior left ventricular walls and interventricular septum moved almost parallel to each other throughout the cardiac cycle, often with exaggerated excursion. In 10 of 13 patients right heart catheterization revealed the hemodynamic profile of cardiac tamponade, while one additional patient was found to have evidence of cardiac compression at the time of surgery. In the remaining two patients no acute invasive diagnostic procedures were performed. During the same observation period cardiac tamponade was observed in five patients without echocardiographic evidence of a swinging heart, and four of these had large clots in the pericardial space. Thus, the swinging heart pattern appears to be a reliable marker of cardiac tamponade, except in those patients with intrapericardial lesions which mechanically limit cardiac motion.

Mitral valve closure in atrial flutter

12 patients who had atrial flutter without clinical, echocardiographic or angiographic evidence of aortic insufficiency were studied with simultaneous echo- and phonocardiograms. In patients with high-grade atrioventricular (AV) block, the mitral valve opened and closed with each flutter wave. Of seven patients, two had persistent and five had intermittent early mitral valve closure before QRS inscription. In five patients (three with 2:1 AV block) the mitral valve closed on time. In one patient with a mitral valve prosthesis, echocardiography and cinefluorography demonstrated closure during mid-diastole, with reopening in late diastole after a flutter wave. Final valve closure occurred before the onset of the QRS, and each closure was associated with a click. Simultaneous phonocardiographic analysis in these patients demonstrated that the first heart sound intensity was inversely related to the degree of mitral valve preclosure. This relationship was independent of the length of the RR interval. Thus, atrial flutter independent of any other cause of abnormal hemodynamics may produce early mitral valve closure. The echocardiographic finding of premature mitral arrhythmias, may not have the same diagnostic or prognostic significance previously described in patients with sinus rhythm and normal AV conduction.

Constrictive pericarditis: early and late complication of cardiac surgery

Constrictive pericarditis is not considered a complication of cardiac surgery. However, three cases are presented in which equalization of diastolic pressures and the ventricular pressure pattern of early diastolic dip-late diastolic plateau, characteristic of restrictive disease, appeared after cardiac surgery. In one patients cardiac constriction developed less than 2 weeks after surgery, and loculated clotted and unclotted viscous blood was removed from the pericardial space. In the other two patients the pericardial space was obliterated by dense adhesions. Thus constrictive pericarditis should be considered in postoperative patients who either do not recuperate satisfactorily after surgery or whose condition deteriorates after initial recovery.

The sudden infant death syndrome and epidemic viral disease

A study was done to investigate the relationship between the sudden infant death syndrome (SIDS) and epidemic respiratory viral disease among hospitalized children under 18 months of age. During the 42 month-period of this study, there were 778 sudden infant deaths in Chicago and 3244 hospital admissions of children under 18 months for respiratory disease. Four outbreaks of respiratory syncytial (RS) virus infections, three outbreaks of influenza A virus infections, and several small clusters of parainfluenza virus infections occurred during the course of this study. Influenza A was the only virus infection found to have a statistically significant association with SIDS. Although environmental temperature was also significantly correlated with SIDS, the association with influenza A virus infection was independent of this temperature effect and neither association was strong.