Refractory systemic hypertension following type B aortic dissection.

C management of acute type B aortic dissection (AD) consists of an initial course of aggressive medical therapy with intravenous b blockers and vasodilators, reserving surgery or endovascular therapies for patients with significant complications of the ADs. Severe, refractory hypertension (rHTN) frequently occurs as a consequence of acute type B AD, even among patients without a history of previous hypertension. Some have considered rHTN to be a high-risk complication because of the concern that it might increase the risk for AD extension or aortic rupture, and have therefore proposed that rHTN is an indication for early surgical intervention. Despite such concerns, however, the phenomenon of rHTN after AD remains poorly described, and the incidence of and risk associated with rHTN are unknown. • • • We used the Massachusetts General Hospital Thoracic Aortic Center database to identify the clinical data for all patients with type B acute AD or intramural hematoma admitted between January 1995 and December 1998. For the present study, patients presenting with an immediate indication for surgical repair (e.g., acute organ or limb ischemia, rupture), chronic AD (symptoms $2 weeks duration), or those with an AD of iatrogenic etiology were excluded from analysis. The baseline clinical variables collected included gender, age, type of aortic syndrome, and history of any of the following: hypertension, atherosclerotic disease, diabetes mellitus, and chronic renal failure (defined as baseline serum creatinine $1.5 mg/dl). The patient records were reviewed for the in-hospital occurrence of rHTN, which we defined for the purpose of the study as a need for $4 adequately dosed antihypertensive agents used simultaneously to achieve a systemic arterial pressure #140/80 mm Hg. In addition, we recorded the maximal number of antihypertensive agents required during hospitalization, as well as the number at discharge. The hospital course was reviewed for adverse events, defined as vascular surgery for any reason, extension of dissection (defined as a change in dissection length as estimated via imaging studies), branch vessel compromise, aneurysm expansion, aortic rupture, and death. The above-mentioned variables were assessed for the group as a whole as well as with respect to the presence of rHTN. All analyses were performed using SPSS software (SPSS, Inc., Chicago, Illinois). When applicable, continuous variables are expressed as mean 6 SD. Univariate analyses were used to compare the frequency, proportion, or distribution of variables between groups. Differences between the groups were assessed using the chi-square or Fisher’s exact test for categorical variables, whereas continuous variables were measured using Student’s unpaired t test. All p values are 2-sided, with values ,0.05 considered significant. The results of our study are detailed in Table 1. Of 62 patients admitted with type B AD during the study period, 53 met inclusion criteria and were analyzed. Of these patients, 34 (64%) developed rHTN. The stratification of patients based on the presence or absence of rHTN demonstrated no differences at baseline with respect to gender, age, or previous medical history. Based on the results of diagnostic imaging studies, among the group as a whole, the mean number of dissected or compromised aortic side branches was 0.6 6 0.6 vessels per patient. This included 10 patients (19%) who had either unilateral (n 5 9) or bilateral (n 5 1) renal artery obstruction of a significant degree. Five patients had an adverse outcome in the hospital: 3 patients required surgery (1 developed visceral ischemia and 2 had evidence of impending aortic rupture) and 2 died suddenly, presumably due to aortic rupture. • • • Despite the fact that rHTN has been considered to be an indication for surgical intervention, its prevalence and clinical significance has not, in fact, been well defined. We demonstrated that among a clinically heterogenous population of patients with type B acute aortic syndromes, rHTN occurs often (64% of patients), presents early in the hospital course, and typically improves by the time of discharge. Although a trend suggested that rHTN was associated with more numerous side branch dissections, it was not associated with a higher likelihood for renal artery compromise. Importantly, rHTN was not associated with a greater maximal aortic diameter than that of those without rHTN. We did note an association between rHTN and recurrent pain; however, we have previously shown that recurrent pain does not predict the need for vascular surgery and is not associated with an increased risk of adverse outcomes after type B AD. Finally, and most important, the presence of rHTN was not associated with an increase in adverse outcomes in this study. From the Thoracic Aortic Center and Cardiology Division, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. Dr. Isselbacher’s address is: Thoracic Aortic Center, Massachusetts General Hospital, 15 Parkman Street, WAC-469, Boston, Massachusetts 02114. E-mail: Eisselbacher@partners.org. Manuscript received January 26, 2001; revised manuscript received and accepted May 2, 2001.