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Mechanism of anterior ST segment depression during acute inferior myocardial infarction: Observations during coronary thrombolysis
560
?A ?NTIANGINAL EFFECTS OF CORWIN, A NEW BETA-ADRENOCEPTOR PARTIAL AGONIST. Detry JR, Decoster PM, Buy J, et al. Am J Cardiol 1984; 53:439-443. The hemodynamic effects of corwin, a cardioselective 0, partial agonist, were studied in nine patients with coronary artery disease, without evidence of heart failure at rest, during submaximal exercise and during exercise-induced angina. With corwin therapy, resting heart rate and pressure rate product were slightly increased. During submaximal exercise, however, heart rate, pressure-rate product, and ST-segment depression were decreased. Angina pectoris was prevented in all patients at the control workload and was accompanied by lower heart rate, pressure-rate product, and decreased ST depression. At rest and during exercise, cardiac output was unchanged with corwin. The authors conclude that corwin is an effective antianginal agent that does not depress left ventricular function as do other P-blocking agents. Its antianginal effects appear to be due to decreases in pressure-rate product and myocardial oxygen requirements during exercise. [Tom Drake, MD]
?? MAGNESIUM THERAPY FOR TORSADES DE POINTES. Tzivoni D, Keren A, Cohen AM, et al. Am J Cardioll984; 53:528530. The authors report on the first successful use of magnesium sulfate (MgSO,) in the treatment of Torsades de Pointes (TdP) in three consecutive patients. In the first patient, TdP was induced by a combination of amiodarone and quinidine, in the second by procainamide, and in the third by an overdose of imiprimine. All patients had prolonged QT intervals. Magnesium sulfate 25% was used in 1.O- to 2.0-g boluses, and a continuous drip was used in one patient. Two of the patients had received isoproterenol without success. Magnesium therapy was successful in all three patients in terminating TdP but.did not alter QT interval or heart rate. It is postulated that MgS04 prevented the reentry circuits responsible for TdP by equalization of myocardial repolarization through its action on membrane electrolyte transport. The authors conclude that magnesium may be a safe and effective mode of therapy in conditions in which isoproterenol is contraindicated, such as acute
The Journal of Emergency Medicine
myocardial infarction or angina. Future clinical trials seem warranted. [Tom Drake, MD]
RESUSCI0 POSTCARDIOPULMONARY TATION PULMONARY EDEMA. Dohi S. Crit Care Med 1983; 11:434-437. Severe pulmonary edema (PE) is occasionally encountered in patients undergoing cardiopulmonary resuscitation (CPR). The author relates his experience in 71 patients who suffered sudden, unexpected cardiac arrest and were resuscitated. Twenty of these patients subsequently developed pulmonary edema. The onset of pulmonary edema ranged from several minutes to 45 minutes postresuscitation. The time required to resumption of pulse in each patient ranged from a few minutes to 120 minutes and was not related to the development of pulmonary edema. In comparing patients with and without PE, the patients with PE had a significantly higher P(A - a)O,, 562 f 55 torr compared with 368 &20 torr at FIO, of 1.0 (P
?M ? ECHANISM OF ANTERIOR ST SEGMENT DEPRESSION DURING ACUTE INFERIOR MYOCARDIAL INFARCTION: OBSERVATIONS DURING CORONARY THROMBOLYSIS. Little WC, Rogers EW, Sodums MT. Ann Int Med 1984; 100:226-229. Acute inferior myocardial infarctions usually arise from a sudden occlusion of the right coronary artery (RCA). Classic ST segment elevation in the inferior leads is often associated with anterior ST segment depression. This ST segment depression has been considered to be a result of concomitant anterior wall ischemia in the area perfused by the left anterior descending
561
Abstracts
coronary artery (LAD). Disrupted collateral flow, a coronary “steal” syndrome, and increased regional myocardial oxygen demand have all been proposed as mechanisms for this anterior ischemia. Seventeen consecutive patients with acute inferior myocardial infarctions undergoing coronary angiography and intracoronary infusion of streptokinase were studied; 14 were found to have anterior segment ST depression. Angiographic examination revealed significant left anterior descending coronary artery disease in 9 of these 14 patients. Intracoronary streptokinase successfully reopened the right coronary artery in 12 patients (7 with LAD disease and 5 without). After reperfusion the anterior ST segment depression and anterior Twave inversion resolved in all patients. Failure of the streptokinase infusion to reopen the artery produced no change in anterior ST segments. There was no angiographic evidence of significant disruption of collateral flow or coronary steal postreperfusion; determinants of anterior myocardial oxygen demand were not altered by reperfusion. The authors conclude that anterior ST segment depression during acute inferior myocardial infarction is a reciprocal reflection of the ischemic injury in the region supplied by the occluded RCA and is not due to anterior ischemia. Anterior ST segment depression may be associated with larger infarctions. [Brian McGowan, MD]
?? LIFE EVENTS AND MYOCARDIAL INFARCTION. Magni G, Corfini A, Berto F, et al. Aust NZ J Med 1983; 13:257-259. A retrospective study was conducted to investigate a previously suggested correlation between the occurrence of significant life events and the onset of myocardial infarction (MI). Fifty-five consecutive patients admitted to the hospital for their first myocardial infarction were interviewed within one month of admission concerning life events that had occurred during the previous 12 months. The investigators used the Paykel revised interview for Recent Life Events, which covers both quantitative and qualitative aspects of 64 life events. Matched controls for acute abdomen, trauma, or multiple trauma were also interviewed. Compared with controls, MI patients reported a significantly greater number of recent life events, with greater objective negative impact of each event,
and their events were more often felt to be undesirable and uncontrolled. Based on the positive association found in this study, the authors suggest that recent life events be considered as possible risk factors in the development of acute myocardial infarction. [Kathryn A. Collins, MD]
?B ?RONCHOGENIC CARCINOMA IN PATIENTS YOUNGER THAN 40 YEARS. Pemberton JH, Nagorney DM, Gilmore JC, et al. Ann Thorac Surg 1983; 36:509-515.
Less than 6% of all patients with bronchogenie carcinoma are less than 40 years of age. Reports have suggested that bronchogenic carcinoma in this group of patients is more rapidly fatal and virulent than that occurring in more elderly persons. To determine if these reports are true, the authors of the present study retrospectively reviewed all patients less than 40 years of age who presented over a 20-year period with a diagnosis of bronchogenic carcinoma. Of the 113 patients studied, 87% smoked regularly, with a mean of 27 pack years; 104 were symptomatic at the time of diagnosis, with a mean duration of symptoms of 4.2 months. The most frequently reported symptoms were persistent cough and thoracic pain, occurring in 78% and 48% of the patients, respectively. Hemoptysis was present in 35%, dyspnea on exertion in 32%, and fever and wheezing in 30%. Anorexia, malaise, or weight loss were present in 86%. Thirty five percent had palpable supraclavicular or axillary adenopathy. Chest x-rays were abnormal in 94% of patients. Stage I disease was found in 8% of patients, Stage II in 5%, and Stage III in 87%. One-year survival in patients with Stage I disease was 82%) 40% with Stage II, and 26% with Stage III. Stage III disease was associated with significantly poorer survival (P= 0.006). The authors conclude that advanced stage rather than a more virulent form of the disease is responsible for the poorer long-term prognosis in patients less than 40 years old. A low index of suspicion with resulting delay in diagnosis may account for this advanced stage of disease. [Deborah Blanton, MD] Editor’s Note: Although it is often easy to dismiss frequent and persistent respiratory complaints in the emergency department as upper respiratory infections, a search for lung carcinoma should be instituted in patients of any
?A ?NTIANGINAL EFFECTS OF CORWIN, A NEW BETA-ADRENOCEPTOR PARTIAL AGONIST. Detry JR, Decoster PM, Buy J, et al. Am J Cardiol 1984; 53:439-443. The hemodynamic effects of corwin, a cardioselective 0, partial agonist, were studied in nine patients with coronary artery disease, without evidence of heart failure at rest, during submaximal exercise and during exercise-induced angina. With corwin therapy, resting heart rate and pressure rate product were slightly increased. During submaximal exercise, however, heart rate, pressure-rate product, and ST-segment depression were decreased. Angina pectoris was prevented in all patients at the control workload and was accompanied by lower heart rate, pressure-rate product, and decreased ST depression. At rest and during exercise, cardiac output was unchanged with corwin. The authors conclude that corwin is an effective antianginal agent that does not depress left ventricular function as do other P-blocking agents. Its antianginal effects appear to be due to decreases in pressure-rate product and myocardial oxygen requirements during exercise. [Tom Drake, MD]
?? MAGNESIUM THERAPY FOR TORSADES DE POINTES. Tzivoni D, Keren A, Cohen AM, et al. Am J Cardioll984; 53:528530. The authors report on the first successful use of magnesium sulfate (MgSO,) in the treatment of Torsades de Pointes (TdP) in three consecutive patients. In the first patient, TdP was induced by a combination of amiodarone and quinidine, in the second by procainamide, and in the third by an overdose of imiprimine. All patients had prolonged QT intervals. Magnesium sulfate 25% was used in 1.O- to 2.0-g boluses, and a continuous drip was used in one patient. Two of the patients had received isoproterenol without success. Magnesium therapy was successful in all three patients in terminating TdP but.did not alter QT interval or heart rate. It is postulated that MgS04 prevented the reentry circuits responsible for TdP by equalization of myocardial repolarization through its action on membrane electrolyte transport. The authors conclude that magnesium may be a safe and effective mode of therapy in conditions in which isoproterenol is contraindicated, such as acute
The Journal of Emergency Medicine
myocardial infarction or angina. Future clinical trials seem warranted. [Tom Drake, MD]
RESUSCI0 POSTCARDIOPULMONARY TATION PULMONARY EDEMA. Dohi S. Crit Care Med 1983; 11:434-437. Severe pulmonary edema (PE) is occasionally encountered in patients undergoing cardiopulmonary resuscitation (CPR). The author relates his experience in 71 patients who suffered sudden, unexpected cardiac arrest and were resuscitated. Twenty of these patients subsequently developed pulmonary edema. The onset of pulmonary edema ranged from several minutes to 45 minutes postresuscitation. The time required to resumption of pulse in each patient ranged from a few minutes to 120 minutes and was not related to the development of pulmonary edema. In comparing patients with and without PE, the patients with PE had a significantly higher P(A - a)O,, 562 f 55 torr compared with 368 &20 torr at FIO, of 1.0 (P
?M ? ECHANISM OF ANTERIOR ST SEGMENT DEPRESSION DURING ACUTE INFERIOR MYOCARDIAL INFARCTION: OBSERVATIONS DURING CORONARY THROMBOLYSIS. Little WC, Rogers EW, Sodums MT. Ann Int Med 1984; 100:226-229. Acute inferior myocardial infarctions usually arise from a sudden occlusion of the right coronary artery (RCA). Classic ST segment elevation in the inferior leads is often associated with anterior ST segment depression. This ST segment depression has been considered to be a result of concomitant anterior wall ischemia in the area perfused by the left anterior descending
561
Abstracts
coronary artery (LAD). Disrupted collateral flow, a coronary “steal” syndrome, and increased regional myocardial oxygen demand have all been proposed as mechanisms for this anterior ischemia. Seventeen consecutive patients with acute inferior myocardial infarctions undergoing coronary angiography and intracoronary infusion of streptokinase were studied; 14 were found to have anterior segment ST depression. Angiographic examination revealed significant left anterior descending coronary artery disease in 9 of these 14 patients. Intracoronary streptokinase successfully reopened the right coronary artery in 12 patients (7 with LAD disease and 5 without). After reperfusion the anterior ST segment depression and anterior Twave inversion resolved in all patients. Failure of the streptokinase infusion to reopen the artery produced no change in anterior ST segments. There was no angiographic evidence of significant disruption of collateral flow or coronary steal postreperfusion; determinants of anterior myocardial oxygen demand were not altered by reperfusion. The authors conclude that anterior ST segment depression during acute inferior myocardial infarction is a reciprocal reflection of the ischemic injury in the region supplied by the occluded RCA and is not due to anterior ischemia. Anterior ST segment depression may be associated with larger infarctions. [Brian McGowan, MD]
?? LIFE EVENTS AND MYOCARDIAL INFARCTION. Magni G, Corfini A, Berto F, et al. Aust NZ J Med 1983; 13:257-259. A retrospective study was conducted to investigate a previously suggested correlation between the occurrence of significant life events and the onset of myocardial infarction (MI). Fifty-five consecutive patients admitted to the hospital for their first myocardial infarction were interviewed within one month of admission concerning life events that had occurred during the previous 12 months. The investigators used the Paykel revised interview for Recent Life Events, which covers both quantitative and qualitative aspects of 64 life events. Matched controls for acute abdomen, trauma, or multiple trauma were also interviewed. Compared with controls, MI patients reported a significantly greater number of recent life events, with greater objective negative impact of each event,
and their events were more often felt to be undesirable and uncontrolled. Based on the positive association found in this study, the authors suggest that recent life events be considered as possible risk factors in the development of acute myocardial infarction. [Kathryn A. Collins, MD]
?B ?RONCHOGENIC CARCINOMA IN PATIENTS YOUNGER THAN 40 YEARS. Pemberton JH, Nagorney DM, Gilmore JC, et al. Ann Thorac Surg 1983; 36:509-515.
Less than 6% of all patients with bronchogenie carcinoma are less than 40 years of age. Reports have suggested that bronchogenic carcinoma in this group of patients is more rapidly fatal and virulent than that occurring in more elderly persons. To determine if these reports are true, the authors of the present study retrospectively reviewed all patients less than 40 years of age who presented over a 20-year period with a diagnosis of bronchogenic carcinoma. Of the 113 patients studied, 87% smoked regularly, with a mean of 27 pack years; 104 were symptomatic at the time of diagnosis, with a mean duration of symptoms of 4.2 months. The most frequently reported symptoms were persistent cough and thoracic pain, occurring in 78% and 48% of the patients, respectively. Hemoptysis was present in 35%, dyspnea on exertion in 32%, and fever and wheezing in 30%. Anorexia, malaise, or weight loss were present in 86%. Thirty five percent had palpable supraclavicular or axillary adenopathy. Chest x-rays were abnormal in 94% of patients. Stage I disease was found in 8% of patients, Stage II in 5%, and Stage III in 87%. One-year survival in patients with Stage I disease was 82%) 40% with Stage II, and 26% with Stage III. Stage III disease was associated with significantly poorer survival (P= 0.006). The authors conclude that advanced stage rather than a more virulent form of the disease is responsible for the poorer long-term prognosis in patients less than 40 years old. A low index of suspicion with resulting delay in diagnosis may account for this advanced stage of disease. [Deborah Blanton, MD] Editor’s Note: Although it is often easy to dismiss frequent and persistent respiratory complaints in the emergency department as upper respiratory infections, a search for lung carcinoma should be instituted in patients of any