Intravenous thrombolysis

However, several important studies have shown that intravenous thrombolysis may be beneficial more than 3 hours after stroke onset, provided that only patients with a significant diffusion-perfusion mismatch are treated. In one such smdy, Ribo et al. found that patients with a significant diffusion-perfusion mismatch could be treated safely and effectively in the 3-6-hour time period. In phase II of the desmo-teplase in acute stroke (DIAS) trial, patients with diffusion-perfusion mismatch were treated with desmoteplase up to 9 hours after stroke onset, and showed better outcomes than patients given placebo, with only a minimal incidence of symptomatic hemorrhage. Similar success was achieved in the same time window by the dose escalation study of desmoteplase in acute ischemic stroke (DEDAS). ... 

These studies raise the possibility that, one day, imaging-based treatment protocols may allow for intravenous thrombolysis in patients well outside of the now-accepted 3-hour window, provided they demonstrate substantial diffusion-perfusion mismatch. Such protocols could allow for treatment of a vastly larger number of patients than are currently treated. It has been estimated that only 1-7% of acute stroke patients currently receive thrombolytic medication, and that, in up to 95% of cases, they are ineligible because they present outside of the 3-hour time window. As many as 80% of patients who present 6 hours after stroke onset may demonstrate a significant diffusion-perfusion mismatch. "... 

Hacke W, Kaste M, Fieschi C, Toni D, Lesaffre E, von Kummer R, Boy sen G, Bluhmki E, Hoxter G, Mahagne MH. Intravenous thrombolysis with recombinant tissue plasminogen activator for acute hemispheric stroke. The European Cooperative Acute Stroke Study (ECASS). JAMA 1995 274 1017-1025. 

TABLE 3.1 Large Randomized Controlled Trials of Intravenous Thrombolysis for Acute Ischemic Stroke. 

Kent DM, Selker HP, Ruthazer R, Bluhmki E, Hacke W. The Stroke-Thrombol3dic Predictive Instrument. A predictive instrument for intravenous thrombolysis in acute ischemic stroke. Stroke. 2006 37 2957-2962. 

The efficacy of IV thrombolysis in patients with moderate-to-severe strokes due to proximal arterial occlusions is restricted by several factors, including the relatively short therapeutic window, poor recanalization rates as the clot burden increases, restrictive eligibility criteria, and the risk of intracerebral hemorrhage. Endovascular techniques improve the rates of recanalization in this patient population, and appear to increase the likelihood of a good functional outcome. Intravenous thrombolysis... 

Lindsberg PJ, Mattie HP. Therapy of basilar artery occlusion a systematic analysis comparing intra-arterial and intravenous thrombolysis. Stroke 2006 37 922-928. 

Keris V, Rudnicka S, Vorona V, Enina G, Tilgale B, Fricbergs J. Combined intraarterial/ intravenous thrombolysis for acute ischemic stroke. Am JNeuroradiol 2001 22 352-358. 

If a stroke patient receives intravenous (IV) thrombolysis, care often continues in the ED until the patient arrives in the ICU. Close monitoring must continue during this time, with special attention to the blood pressure. The blood pressure is most commonly checked via an arm cuff, since the placement of invasive lines (e.g., arterial catheterization) is relatively contraindicated once the patient has received intravenous thrombolysis (unless the situation is emergent and mandates such treatment). The systolic pressure must not exceed 185 mm Hg, and the diastolic pressure limit should be 110 mm Hg. Should the blood pressure exceed these limits, IV antihypertensive agents should be administered. IV pushes of labetolol (10-20 mg over 1-2 minutes) may be effective, but if patients are refractory to these initial measures then a continuous infusion of labetolol (0.5-2.0 mg/minute), nicardipine (5-15 mg/hour), or nitro-prusside (0.25-10 mg/kg/minute) may be necessary to keep the patient s blood pressure within the range. There will be a more detailed discussion of these antihypertensive agents, including their side effect profiles, later in this chapter. 

Comparisons between the different intra-arterial thrombolysis trials and between intraarterial thrombolysis and intravenous thrombolysis is hampered by differences in methodology and type of thrombolytic therapy. In addition, within the intra-arterial thrombolysis trials, thrombolytic deUvery has varied between regional into a parent vessel of the thrombosed vessel, local into the affected artery and into the thrombus itself, or combinations of these methods. In addition, the infusion process has been variable, ranging from continuous to pulsed infusion. Some studies have allowed physical clot dispersion using the tip of the microcatheter while this was prohibited in others, for instance in the PROACT trials. 

Jorgensen HS, Nakayama H, Kammersgaard LP et al. (1999). Predicted impact of intravenous thrombolysis on prognosis of general population of stroke patients simulation model. British Medical Journal 319 288-289... 

Lindsberg PJ, Mattie HP (2006). Therapy of basilar artery occlusion a systematic analysis comparing intra-arterial and intravenous thrombolysis. Stroke 37 922-928 Lindsberg PJ, Soinne L, Tatlisumak T et al. (2004). Long-term outcome after intravenous thrombolysis of basilar artery occlusion. Journal of the American Medical Association 292 1862-1866... 

Jolliet P, Magnin C, Unger PF. Pulmonary embolectomy after intravenous thrombolysis with alteplase. Lancet 1990 335(8684) 290-1. 

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