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Thrombolytic therapy of massive pulmonary embolism during prolonged cardiac arrest using recombinant tissue-type plasminogen activator
CASE REPORT tissue Dlasminogen activator, pulmonary embolism
Thrombolytic Therapy of Massive Pulmonary Embolism During Prolonged Cardiac Arrest Using Recombinant Tissue-Type Plasminogen Activator Cardiac arrest caused by massive pulmonary embolism is highly refractory to conventional resuscitation. Emergency surgical embolectomy has been considered the only effective intervention. We present the case of a 33-year-old woman who suffered a massive pulmonary embolism with circulatory arrest refractory to one half hour of aggressive CPR. A lO-mg bolus of recombinant tissue-type plasrninogen activator was administered through a central line followed by a further 90-mg IV infusion over two hours. Rapid hemodynarnic and clinical improvement followed the bolus dose. The patient was discharged later without neurological or other sequelae. This is the first reported case of successful thrornbolytic therapy of massive pulmonary embolism during prolonged CPR. [Langdon RW,, Swicegood WR, Schwartz DA: Thrombolytic therapy of massive pulmonary embolism during prolonged cardiac arrest using recombinant tissuetype plasminogen activator. Ann Emerg Med June 1989;18:67&680.] INTRODUCTION Cardiac arrest caused by massive pulmonary embolism is highly lethal, often characterized by nonperfusing cardiac rhythms refractory to conventional resuscitation. The most effective intervention has been rapid surgical embolectomy, but the mortality is high. 1-3 In very rare instances, vigorous external chest massage with cardiopulmonary bypass has produced fragmentation and distal migration of the obstructing clot. 4,5 Thrornbolytic therapy has been considered ineffective, 3 and transvenous catheter em~ bolectomy cannot be performed in the setting of cardiac arrest. 6 Recent studies have demonstrated accelerated lysis of pulmonary emboli by IV recombinant tissue-type phisminogen activator (rtPA). 7-9 We present the first reported case of successful thrombolytic therapy of a massive pulmonary embolism during prolonged cardiac arrest using IV rtPA.
Robert W Langdon, MD, FACEP William R Swicegood, MD David A Schwartz, MD, FACC Dallas, Texas From the Emergency Department, Hospital Corporation of America Medical Center of Plane, Piano, Texas. Received for publication February 20, 1989. Accepted for publication March 21, 1989. Address f(~r reprints: Robert W Langdon, MD, 6764 Winterwood, Dallas, Texas 75248.
CASE REPORT A 33-year-old woman presented to the emergency department in cardiac arrest. One week earlier she had had an abdominal hysterectomy. On the day of admission she experienced a brief syncopal episode and sudden extreme dyspnea. The paramedics found her awake but hypotensive, and she deteriorated during transport to the hospital. On presentation to the ED the patient was unconscious, apneic, and pulseless. The cardiac monitor showed a slow idioventricular rhythm. CPR was initiated with closed-chest compression and endotracheal intubation and ventilation. Epinephrine, atropine, dopamine, bicarbonate, and fluids were administered intravenously. Arterial blood gases following intubation were pH, 6.86; pCO~, 27 m m Hg; pO2, 28 m m Hg; and O~ saturation, 24%. Despite aggressive resuscitation for 30 minutes, the patient remained in a pulseless idioventricular rhythm with rates between 20 and 90. Considering the grave nature of her condition in the face of what appeared to be a massive pulmonary embolism, the decision to administer rtPA was made. A 10-mg bolus of rtPA was administered through a central venous catheter, followed by a constant infusion of rtPA for a total dose of 100 mg over two hours. Within moments of administration of the bolus dose, t h e patient developed a palpable pulse and a sinus rhythm. Although she remained unresponsive, she soon had a tachycardia and a systolic blood pressure of 121 18:6 June 1989
Annals of Emergency Medicine
678/117
rtPA Langdon, Swicegood & SchwaRz
m m Hg. She was transported to the cardiac catheterization laboratory, where a Swan-Ganz catheter was placed, d e m o n s t r a t i n g a m e a n pulm o n a r y artery pressure of 61 m m Hg. A p p r o x i m a t e l y 30 m i n u t e s later (90 m i n u t e s after rtPA was begun), pulm o n a r y artery pressure was 38 m m Hg. Further evidence of massive pulm o n a r y e m b o l i s m was d e m o n s t r a t e d by p u l m o n a r y a r t e r i o g r a p h y that revealed a large left m a i n p u l m o n a r y embolus with poor flow distally. M u l t i p l e proximal and distal emboli were n o t e d in the right p u l m o n a r y artery system, but the right main p u l m o n a r y artery was free of significant clot. By the end of the procedure, while still receiving rtPA infusion, p u l m o nary artery pressure c o n t i n u e d to fall, u r i n e o u t p u t b e c a m e brisk, and the p a t i e n t b e g a n to r e g a i n c o n s c i o u s ness. She was transported to the int e n s i v e care u n i t w h e r e blood pressure was "118/80 m m Hg and heparin infusion was begun. Later in t h e day, a Greenfield filter was placed in the inferior vena cava w i t h o u t i n c i d e n t . T h e p a t i e n t rem a i n e d h o s p i t a l i z e d for eight days. W h o l e blood fibrinogen levels were 3.06 g/L and 3.94 g / L on the second and t h i r d h o s p i t a l i z e d days, respectively. T h e r e was bleeding into the pelvis at the recent h y s t e r e c t o m y site that required surgical evacuation. This procedure was tolerated well. T h e p a t i e n t w a s d i s c h a r g e d on low-dose warfarin and has subseq u e n t l y r e t u r n e d to w o r k w i t h o u t further problems. DISCUSSION One patient's d r a m a t i c response to r t P A suggests t h a t r a p i d l y s i s of a massive p u l m o n a r y e m b o l i s m can be accomplished during prolonged CPR. We d o u b t t h a t c h e s t c o m p r e s s i o n s alone caused fragmentation and distal m i g r a t i o n of the clot. This phen o m e n o n is e x c e e d i n g l y rare, w i t h only one reported case in the literature. F u r t h e r m o r e , w h i l e v i g o r o u s m a s s a g e p r o d u c e d no p u l s e for 30 minutes, a d m i n i s t r a t i o n of rtPA was followed a l m o s t i m m e d i a t e l y by hemodynamic improvement. P r o l o n g e d CPR has b e e n c o n s i d ered a contraindication to thrombol y t i c t h e r a p y , lo 1~ E x t e r n a l c a r d i a c m a s s a g e can i n j u r e a b d o m i n a l and t h o r a c i c s t r u c t u r e s t h a t m a y be the source of life-threatening hemorrhage 118/679
if t h r o m b o l y t i c agents are a d m i n i s tered. But here a d i s t i n c t i o n m u s t be made. Whereas cardiac arrest in myocardial infarction m a y be successfully t r e a t e d w i t h o u t l y s i s of t h e occ l u d i n g c o r o n a r y t h r o m b u s , circulatory arrest due to massive p u l m o n a r y e m b o l i s m will be fatal unless the obs t r u c t i o n to c i r c u l a t i o n is r e m o v e d . In this situation, the risk of bleeding is justified, and t h r o m b o l y t i c therapy is not contraindicated. A n o t h e r long-standing view is that surgical e m b o l e c t o m y offers the only hope for p a t i e n t s dying of m a s s i v e p u l m o n a r y e m b o l i s m . 1-3 Successful e m b o l e c t o m y has followed periods of external massage as long as 90 minutes. 1-3 T h i s p r o c e d u r e is m o s t successful w h e n performed w i t h cardiop u l m o n a r y bypass. In one series of t e n p a t i e n t s w i t h c a r d i a c a r r e s t at t i m e of surgery w i t h bypass, five surv i v e d , l In c o n t r a s t , a s e r i e s of 16 pulseless patients undergoing embolectomy without bypass produced only one survivor. 2 T h r o l ~ b o l y t i c t h e r a p y offers several p o t e n t i a l a d v a n t a g e s o v e r surgery. It m a y be a d m i n i s t e r e d rapidly w i t h o u t the expertise and resources r e q u i r e d of surgery. It is effective therapy for acute m y o c a r d i a l infarction, t h e m i s d i a g n o s i s m o s t o f t e n found at surgery. T h r o m b o l y t i c therapy does n o t p r e c l u d e s u r g e r y a n d m a y lyse smaller emboli in the distal pulmonary vasculature inaccessible to the surgeon. Unfortunately, diagnosing pulmonary e m b o l i s m during cardiac arrest m a y be impossible because diagnost i c procedures cannot be performed. If t h r o m b o l y t i c agents are given during arrest due to bleeding events such as aortic dissection, pericardial tamponade, or hemorrhage of the gastroi n t e s t i n a l or nervous system, the res u l t s m a y be d i s a s t r o u s . A r e c e n t series of s u d d e n d e a t h in 83 y o u n g adults included 11 cases secondary to bleeding but only two cases of pulm o n a r y e m b o l i s m . 14 O t h e r s t u d i e s bear o u t t h e r e l a t i v e f r e q u e n c y of bleeding events in arrested a d u l t s . I S , 16 I n d i s c r i m i n a t e u s e of t h r o m b o l y t i c agents in such patients w o u l d m o r e l i k e l y than not be deleterious. Yet there are patients, such as ours, in w h o m the c l i n i c a l p i c t u r e overw h e l m i n g l y suggests p u l m o n a r y embolism. If cardiac arrest is refractory to aggressive r e s u s c i t a t i o n and volAnnals of Emergency Medicine
u m e loading, the p a t i e n t will die unless the o b s t r u c t i o n to circulation is removed. Rapid e m b o l e c t o m y w i t h c a r d i o p u l m o n a r y bypass is often not feasible. In such c i r c u m s t a n c e s we believe t h a t c e n t r a l l y a d m i n i s t e r e d rtPA is a desperat4 b u t p o t e n t i a l l y life-saving a l t e r n a t i v e and warrants further study. SUMMARY We present the first reported case of successful t h r o m b o l y t i c therapy of a massive p u l m o n a r y e m b o l i s m during prolonged CPR. There are significant hazards associated w i t h this app r o a c h ; h o w e v e r , p r o l o n g e d CPR alone is rarely successful in massive p u l m o n a r y e m b o l i s m . Surgical emb o l e c t o m y in t h e a r r e s t e d p a t i e n t m a y not be feasible and the m o r t a l i t y is high. Therefore, centrally administered IV rtPA m a y be an alternative approach, b u t w i l l r e q u i r e f u r t h e r study. REFERENCES 1. Glassford DM Jr, Alford WC Jr, Burrus CR, et al: Pulmonary embolectomy. Ann Thorac Surg 1981;32:28-32. 2. Clarke DB: Pulmonary embolectomy reevaluated. Ann R Coll Surg Engl 1981;63:18-24. 3. Weatherford SC, Lawrie GM: Trendelenburg embolectomy for cardiac arrest secondary to massive pulmonary embolism. Can ] Surg 1986;29:383-384. 4: Heimbecker RO, Keon WJ, Richards KU: Massive pulmonary embolism: A new look at surgichl management. Arch Surg 1973;107: 740-746. 5. Oakley CM: Conservative management of pulmonary embolism. Br J Surg 1968;55: 801-805. 6. Greenfield LJ, Zocco JJ: Intraluminal man h agement of acute massive pulmonary thromboembolism. J Thorac C a r d i o v a s c Surg 1979;77:402-410. 7. Come PC, Duchsook K, Parker AJ, et al: Early reversal of right ventricular dysfunction in patients with acute puhnonary embolism after treatment with intravenous tissue plasminogen activator. J A m Coll Cardiol 1987;10:971-978. 8. Goldhaber SZ, Mqyerovitz MF, Markis JE, et al: Thrombolytic therapy of acute pulmonary embolism: Current status and future potential. J A m Col] Cardiol 1987f10:96B-104B. 9. Verstraete M, Miller GAH, Bounameaux H, et al: Intravenous and intrapulmonary recombinant tissue-type plasminogen activator in the treatment of acute massive pulmonary embolism. Circulation 1988;77:353-360. 10. Kennedy JW, Atkins JM, Goldstein 8, et al: Recent changes in management of acute myocardial infarction: Implications for emergency care physicians. [ A m Coll Cardiol 1988;11: 446-449. 11. Ansari A: Acute and chronic pulmonary thromboembolism: Current perspectives, Part 18:6 June 1989
V: Management. Clin Cardiol 1986;9:614-620. 12. T h r o m b o l y t i c Therapy in Thrombosis: A NationaI Institutes of Health Consensus Develo p m e n t Conference. Ann Intern Med 1980; 93:141-144. 13. Wester HA, Orellano L, Fenyes-Belhnan J, et
18:6June 1989
al: Successful treatment of massive pulmonary embolism after 90-minute external cardiac mass a g e . D t s c h M e d W o c h e n s c h r 1986;111: 1151-1154.
15. Clinton JE, McGill J, Irwin G, et ah Cardiac arrest under age 40: Etiology and prognosis. Ann Emerg Med 1984;13:1011-1015.
14. Raymond JR, Egerton KB, Knapp MJ: Nont r a u m a t i c prehospital sudden death in young aduIts. Arch Intern Med 1988;148:303-308.
16. Luke JL, H e l p e m M: Sudden u n e x p e c t e d death from natural causes in young adults. Arch Pathol 1968;85:10-17. '
Annals of Emergency Medicine
680/119
Thrombolytic Therapy of Massive Pulmonary Embolism During Prolonged Cardiac Arrest Using Recombinant Tissue-Type Plasminogen Activator Cardiac arrest caused by massive pulmonary embolism is highly refractory to conventional resuscitation. Emergency surgical embolectomy has been considered the only effective intervention. We present the case of a 33-year-old woman who suffered a massive pulmonary embolism with circulatory arrest refractory to one half hour of aggressive CPR. A lO-mg bolus of recombinant tissue-type plasrninogen activator was administered through a central line followed by a further 90-mg IV infusion over two hours. Rapid hemodynarnic and clinical improvement followed the bolus dose. The patient was discharged later without neurological or other sequelae. This is the first reported case of successful thrornbolytic therapy of massive pulmonary embolism during prolonged CPR. [Langdon RW,, Swicegood WR, Schwartz DA: Thrombolytic therapy of massive pulmonary embolism during prolonged cardiac arrest using recombinant tissuetype plasminogen activator. Ann Emerg Med June 1989;18:67&680.] INTRODUCTION Cardiac arrest caused by massive pulmonary embolism is highly lethal, often characterized by nonperfusing cardiac rhythms refractory to conventional resuscitation. The most effective intervention has been rapid surgical embolectomy, but the mortality is high. 1-3 In very rare instances, vigorous external chest massage with cardiopulmonary bypass has produced fragmentation and distal migration of the obstructing clot. 4,5 Thrornbolytic therapy has been considered ineffective, 3 and transvenous catheter em~ bolectomy cannot be performed in the setting of cardiac arrest. 6 Recent studies have demonstrated accelerated lysis of pulmonary emboli by IV recombinant tissue-type phisminogen activator (rtPA). 7-9 We present the first reported case of successful thrombolytic therapy of a massive pulmonary embolism during prolonged cardiac arrest using IV rtPA.
Robert W Langdon, MD, FACEP William R Swicegood, MD David A Schwartz, MD, FACC Dallas, Texas From the Emergency Department, Hospital Corporation of America Medical Center of Plane, Piano, Texas. Received for publication February 20, 1989. Accepted for publication March 21, 1989. Address f(~r reprints: Robert W Langdon, MD, 6764 Winterwood, Dallas, Texas 75248.
CASE REPORT A 33-year-old woman presented to the emergency department in cardiac arrest. One week earlier she had had an abdominal hysterectomy. On the day of admission she experienced a brief syncopal episode and sudden extreme dyspnea. The paramedics found her awake but hypotensive, and she deteriorated during transport to the hospital. On presentation to the ED the patient was unconscious, apneic, and pulseless. The cardiac monitor showed a slow idioventricular rhythm. CPR was initiated with closed-chest compression and endotracheal intubation and ventilation. Epinephrine, atropine, dopamine, bicarbonate, and fluids were administered intravenously. Arterial blood gases following intubation were pH, 6.86; pCO~, 27 m m Hg; pO2, 28 m m Hg; and O~ saturation, 24%. Despite aggressive resuscitation for 30 minutes, the patient remained in a pulseless idioventricular rhythm with rates between 20 and 90. Considering the grave nature of her condition in the face of what appeared to be a massive pulmonary embolism, the decision to administer rtPA was made. A 10-mg bolus of rtPA was administered through a central venous catheter, followed by a constant infusion of rtPA for a total dose of 100 mg over two hours. Within moments of administration of the bolus dose, t h e patient developed a palpable pulse and a sinus rhythm. Although she remained unresponsive, she soon had a tachycardia and a systolic blood pressure of 121 18:6 June 1989
Annals of Emergency Medicine
678/117
rtPA Langdon, Swicegood & SchwaRz
m m Hg. She was transported to the cardiac catheterization laboratory, where a Swan-Ganz catheter was placed, d e m o n s t r a t i n g a m e a n pulm o n a r y artery pressure of 61 m m Hg. A p p r o x i m a t e l y 30 m i n u t e s later (90 m i n u t e s after rtPA was begun), pulm o n a r y artery pressure was 38 m m Hg. Further evidence of massive pulm o n a r y e m b o l i s m was d e m o n s t r a t e d by p u l m o n a r y a r t e r i o g r a p h y that revealed a large left m a i n p u l m o n a r y embolus with poor flow distally. M u l t i p l e proximal and distal emboli were n o t e d in the right p u l m o n a r y artery system, but the right main p u l m o n a r y artery was free of significant clot. By the end of the procedure, while still receiving rtPA infusion, p u l m o nary artery pressure c o n t i n u e d to fall, u r i n e o u t p u t b e c a m e brisk, and the p a t i e n t b e g a n to r e g a i n c o n s c i o u s ness. She was transported to the int e n s i v e care u n i t w h e r e blood pressure was "118/80 m m Hg and heparin infusion was begun. Later in t h e day, a Greenfield filter was placed in the inferior vena cava w i t h o u t i n c i d e n t . T h e p a t i e n t rem a i n e d h o s p i t a l i z e d for eight days. W h o l e blood fibrinogen levels were 3.06 g/L and 3.94 g / L on the second and t h i r d h o s p i t a l i z e d days, respectively. T h e r e was bleeding into the pelvis at the recent h y s t e r e c t o m y site that required surgical evacuation. This procedure was tolerated well. T h e p a t i e n t w a s d i s c h a r g e d on low-dose warfarin and has subseq u e n t l y r e t u r n e d to w o r k w i t h o u t further problems. DISCUSSION One patient's d r a m a t i c response to r t P A suggests t h a t r a p i d l y s i s of a massive p u l m o n a r y e m b o l i s m can be accomplished during prolonged CPR. We d o u b t t h a t c h e s t c o m p r e s s i o n s alone caused fragmentation and distal m i g r a t i o n of the clot. This phen o m e n o n is e x c e e d i n g l y rare, w i t h only one reported case in the literature. F u r t h e r m o r e , w h i l e v i g o r o u s m a s s a g e p r o d u c e d no p u l s e for 30 minutes, a d m i n i s t r a t i o n of rtPA was followed a l m o s t i m m e d i a t e l y by hemodynamic improvement. P r o l o n g e d CPR has b e e n c o n s i d ered a contraindication to thrombol y t i c t h e r a p y , lo 1~ E x t e r n a l c a r d i a c m a s s a g e can i n j u r e a b d o m i n a l and t h o r a c i c s t r u c t u r e s t h a t m a y be the source of life-threatening hemorrhage 118/679
if t h r o m b o l y t i c agents are a d m i n i s tered. But here a d i s t i n c t i o n m u s t be made. Whereas cardiac arrest in myocardial infarction m a y be successfully t r e a t e d w i t h o u t l y s i s of t h e occ l u d i n g c o r o n a r y t h r o m b u s , circulatory arrest due to massive p u l m o n a r y e m b o l i s m will be fatal unless the obs t r u c t i o n to c i r c u l a t i o n is r e m o v e d . In this situation, the risk of bleeding is justified, and t h r o m b o l y t i c therapy is not contraindicated. A n o t h e r long-standing view is that surgical e m b o l e c t o m y offers the only hope for p a t i e n t s dying of m a s s i v e p u l m o n a r y e m b o l i s m . 1-3 Successful e m b o l e c t o m y has followed periods of external massage as long as 90 minutes. 1-3 T h i s p r o c e d u r e is m o s t successful w h e n performed w i t h cardiop u l m o n a r y bypass. In one series of t e n p a t i e n t s w i t h c a r d i a c a r r e s t at t i m e of surgery w i t h bypass, five surv i v e d , l In c o n t r a s t , a s e r i e s of 16 pulseless patients undergoing embolectomy without bypass produced only one survivor. 2 T h r o l ~ b o l y t i c t h e r a p y offers several p o t e n t i a l a d v a n t a g e s o v e r surgery. It m a y be a d m i n i s t e r e d rapidly w i t h o u t the expertise and resources r e q u i r e d of surgery. It is effective therapy for acute m y o c a r d i a l infarction, t h e m i s d i a g n o s i s m o s t o f t e n found at surgery. T h r o m b o l y t i c therapy does n o t p r e c l u d e s u r g e r y a n d m a y lyse smaller emboli in the distal pulmonary vasculature inaccessible to the surgeon. Unfortunately, diagnosing pulmonary e m b o l i s m during cardiac arrest m a y be impossible because diagnost i c procedures cannot be performed. If t h r o m b o l y t i c agents are given during arrest due to bleeding events such as aortic dissection, pericardial tamponade, or hemorrhage of the gastroi n t e s t i n a l or nervous system, the res u l t s m a y be d i s a s t r o u s . A r e c e n t series of s u d d e n d e a t h in 83 y o u n g adults included 11 cases secondary to bleeding but only two cases of pulm o n a r y e m b o l i s m . 14 O t h e r s t u d i e s bear o u t t h e r e l a t i v e f r e q u e n c y of bleeding events in arrested a d u l t s . I S , 16 I n d i s c r i m i n a t e u s e of t h r o m b o l y t i c agents in such patients w o u l d m o r e l i k e l y than not be deleterious. Yet there are patients, such as ours, in w h o m the c l i n i c a l p i c t u r e overw h e l m i n g l y suggests p u l m o n a r y embolism. If cardiac arrest is refractory to aggressive r e s u s c i t a t i o n and volAnnals of Emergency Medicine
u m e loading, the p a t i e n t will die unless the o b s t r u c t i o n to circulation is removed. Rapid e m b o l e c t o m y w i t h c a r d i o p u l m o n a r y bypass is often not feasible. In such c i r c u m s t a n c e s we believe t h a t c e n t r a l l y a d m i n i s t e r e d rtPA is a desperat4 b u t p o t e n t i a l l y life-saving a l t e r n a t i v e and warrants further study. SUMMARY We present the first reported case of successful t h r o m b o l y t i c therapy of a massive p u l m o n a r y e m b o l i s m during prolonged CPR. There are significant hazards associated w i t h this app r o a c h ; h o w e v e r , p r o l o n g e d CPR alone is rarely successful in massive p u l m o n a r y e m b o l i s m . Surgical emb o l e c t o m y in t h e a r r e s t e d p a t i e n t m a y not be feasible and the m o r t a l i t y is high. Therefore, centrally administered IV rtPA m a y be an alternative approach, b u t w i l l r e q u i r e f u r t h e r study. REFERENCES 1. Glassford DM Jr, Alford WC Jr, Burrus CR, et al: Pulmonary embolectomy. Ann Thorac Surg 1981;32:28-32. 2. Clarke DB: Pulmonary embolectomy reevaluated. Ann R Coll Surg Engl 1981;63:18-24. 3. Weatherford SC, Lawrie GM: Trendelenburg embolectomy for cardiac arrest secondary to massive pulmonary embolism. Can ] Surg 1986;29:383-384. 4: Heimbecker RO, Keon WJ, Richards KU: Massive pulmonary embolism: A new look at surgichl management. Arch Surg 1973;107: 740-746. 5. Oakley CM: Conservative management of pulmonary embolism. Br J Surg 1968;55: 801-805. 6. Greenfield LJ, Zocco JJ: Intraluminal man h agement of acute massive pulmonary thromboembolism. J Thorac C a r d i o v a s c Surg 1979;77:402-410. 7. Come PC, Duchsook K, Parker AJ, et al: Early reversal of right ventricular dysfunction in patients with acute puhnonary embolism after treatment with intravenous tissue plasminogen activator. J A m Coll Cardiol 1987;10:971-978. 8. Goldhaber SZ, Mqyerovitz MF, Markis JE, et al: Thrombolytic therapy of acute pulmonary embolism: Current status and future potential. J A m Col] Cardiol 1987f10:96B-104B. 9. Verstraete M, Miller GAH, Bounameaux H, et al: Intravenous and intrapulmonary recombinant tissue-type plasminogen activator in the treatment of acute massive pulmonary embolism. Circulation 1988;77:353-360. 10. Kennedy JW, Atkins JM, Goldstein 8, et al: Recent changes in management of acute myocardial infarction: Implications for emergency care physicians. [ A m Coll Cardiol 1988;11: 446-449. 11. Ansari A: Acute and chronic pulmonary thromboembolism: Current perspectives, Part 18:6 June 1989
V: Management. Clin Cardiol 1986;9:614-620. 12. T h r o m b o l y t i c Therapy in Thrombosis: A NationaI Institutes of Health Consensus Develo p m e n t Conference. Ann Intern Med 1980; 93:141-144. 13. Wester HA, Orellano L, Fenyes-Belhnan J, et
18:6June 1989
al: Successful treatment of massive pulmonary embolism after 90-minute external cardiac mass a g e . D t s c h M e d W o c h e n s c h r 1986;111: 1151-1154.
15. Clinton JE, McGill J, Irwin G, et ah Cardiac arrest under age 40: Etiology and prognosis. Ann Emerg Med 1984;13:1011-1015.
14. Raymond JR, Egerton KB, Knapp MJ: Nont r a u m a t i c prehospital sudden death in young aduIts. Arch Intern Med 1988;148:303-308.
16. Luke JL, H e l p e m M: Sudden u n e x p e c t e d death from natural causes in young adults. Arch Pathol 1968;85:10-17. '
Annals of Emergency Medicine
680/119