Pollutant transport during a regional O3-episode in the mid-Atlantic states

Ozone (O3) concentrations in the Baltimore-Washington (B-W) metropolitan area frequently exceed the National Ambient Air Quality Standard (NAAQS) in the summer months. The most extreme O3 events occur in multi-day high O3 episodes. These events can be regional in scale, with O3 concentrations exceeding the NAAQS at numerous locations along the eastern U.S. seaboard, and are typically associated with slow-moving or stagnant high pressure systems. In the B-W region, the most extreme events typically occur with surface high pressure overhead or just west of the region and an upper air high-pressure area (ridge) to the west or northwest. Besides providing conditions conductive to local O3 production (subsidence and strong low-level inversions, weak horizontal winds, little cloud cover), this weather pattern may also result in transport of O3 and its precursors from heavily industrialized areas west and north of the B-W region. In this paper, observations and back trajectories made during the severe regional O3 event of July 12-15, 1995, are used to confirm the hypothesis that significant regional-scale transport of O3 and its precursors occur during extreme O3 events of the standard type in the B-W area.

Routine coronary angiography for effort angina

OBJECTIVE

To compare the value of exercise testing and coronary angiography in the management of patients with effort angina.

DESIGN

A retrospective follow-up study.

SETTING

A university teaching hospital.

PATIENTS

Four hundred and thirty-four patients with a history of angina, who developed pain or ST segment changes during an exercise test and who were followed-up at up to nine years after their exercise test.

INTERVENTIONS

Coronary angiography was offered to patients for disabling angina only. Bypass surgery was generally offered to patients with multiple vessel coronary artery obstruction.

MAIN OUTCOME MEASURE

Patient survival.

RESULTS

Stepwise regression analysis based on the Cox proportional hazards model indicated that the decision to perform coronary angiography (P less than 0.001) and the amount of ST segment depression on exercise testing (P less than 0.01) were predictors of survival. With ST segment depression set at 1 mm and age set at 53.5 years (both sample median values) the probability of survival at five years was 86% in patients who did not undergo coronary angiography compared with 96% in patients who did undergo angiography. There were eight deaths in 59 patients who did not show any ST segment depression during the exercise test and who were treated medically without coronary angiography.

CONCLUSIONS

Coronary angiography is a superior technique to exercise testing for detecting patients with effort angina who are at high risk of premature mortality. Coronary bypass surgery makes a big improvement in the chance of five-year survival in such patients.

Assessment of cardiac risk 10 days after uncomplicated myocardial infarction

A total of 188 patients with uncomplicated acute myocardial infarction (long-term Norris prognostic index 3.2) were rapidly mobilised, underwent a symptom-limited exercise test around the day of discharge from hospital (day 10), and returned to work at a median of six weeks after the acute event. The incidence of cardiac death six months, one year, and three years after infarction was 2.7%, 4.5%, and 7.3% respectively, and the corresponding figures for recurrent heart attacks were 3.4%, 8.2%, and 18.5% respectively. The risk of recurrence of heart attack was predicted by three variables assessed at discharge--namely, a history of classical effort angina (p less than 0.01), radiological heart failure (p less than 0.05), and angina induced by the exercise test (p less than 0.05). The presence of any of these risk factors defined a group of patients with a sevenfold risk of recurrent heart attacks within six months of the initial acute infarct. It is concluded that these risk factors identify a group of patients with a high risk of recurrence early after infarction, in whom vigorous secondary prophylaxis is desirable.

Effects of morphine on left ventricular dimensions and function in patients with previous myocardial infarction

To assess the effects of morphine sulfate on left ventricular function and dimensions we administered 15 mg of this agent to 11 stable patients with previous transmural myocardial infarction. All studies were carried out in the supine position. Before morphine administration an echocardiogram was obtained, and this procedure was repeated at 15, 30, 60, 120, and 240 min after morphine. Heart rate decreased from a control value of 69 +/- 4 to 62 +/- 5 beats/min 2 h after morphine (p less than 0.01, analysis of variance); this slower heart rate persisted for 4 h after morphine. Serial measurements of blood pressure, echocardiographic ejection fraction, percent of fractional shortening, and mean normalized velocity of circumferential fiber shortening also showed no significant alterations after morphine. We conclude that in stable patients with chronic ischemic heart disease studied in the supine position, 1) morphine exerts no effect on left ventricular dimensions, an observation which does not support the concept that this agent acts in humans by producing a 'pharmacologic phlebotomy'; and 2) morphine does not alter left ventricular function at rest. Whether different results will be found in patients with increased sympathetic activity, such as occurs in the setting of an acute myocardial infarction or during an episode of acute pulmonary edema, remains to be investigated.

Effects of tocainide on left ventricular performance at rest and during acute alterations in heart rate and systemic arterial pressure. An echocardiographic study

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Severe mycoplasma pneumonia

A patient who developed who developed a protracted illness following severe mycoplasma pneumonia is described. The acute phase of the infection was complicated by myocarditis and haemolytic anaemia. The respiratory symptoms abated and lung function tests improved with the administration of systemic and inhaled corticosteroids.