Exercise Testing in Patients with Aortic Stenosis: Discussion
In this patient, inadequate attention had been paid to warning signs. The initial heavy workload of the Bruce protocol (5 METs), infrequent blood pressure monitoring, continuation of the test despite a blunted blood pressure response, and physician inexperience may all have contributed to this catastrophe. Fortunately, the patient survived and underwent successful valve replacement Recent studies have improved our understanding of the patient with AS, and this knowledge will help prevent such events. www.canadian-familypharmacy.com
Lombard and Selzer have discussed the changing character of aortic stenosis. The previously taught classic findings may be missing in the elderly patient; a soft systolic murmur may be present in 10 percent of this population, and the result of carotid examination may be misleading. Coronary artery disease was observed in 60 pecent of patients with AS, and two important categories of symptoms have been profiled: angina/syncope or prefailure symptoms, and dyspnea/ congestive heart failure, indicating various degrees of left ventricular dysfunction.
Since Gallavardin first described syncope in AS, with physical findings during syncope including reduced systolic pressure, an absence of pulses and apical impulse, and disappearance of murmurs with return to baseline upon recovery, several authors have hypothesized various mechanisms for effort syncope in AS. Marvin and Sullivan proposed carotid artery hyperreactivity and inadequate cardiac output leading to “cerebral anemia” and syncope. Flamm et al felt that in 29 patients with near syncope, an inadequate ability to increase cardiac output during exercise because of left ventricular failure was the cause. Schwartz et al reviewed nine cases free of neurologic disease who had syncopal events over a six-year period. Because of the numerous atrial and ventricular arrhythmias observed, they suggested that arrhythmias were the source for syncopal attacks.