An 81-year-old man comes to the office due to dizziness and near falls. The patient's daughter reports that, over the past 2 weeks, the patient has stated that he experiences intermittent lightheadedness and he sometimes "appears wobbly" and almost falls, most notably in the morning after getting out of bed. Medical history is significant for hypertension and Alzheimer dementia. He takes amlodipine and was recently started on quetiapine for aggressive behavior toward caregivers and delusions that his daughter has been cloned. Temperature is 37 C (98.6 F), blood pressure is 105/66 mm Hg, and pulse is 95/min. Pulse oximetry is 96% on room air. The patient is awake, alert, and oriented to person and place. Heart sounds are regular and without murmurs. The lungs are clear to auscultation bilaterally. Strength is 5/5 in the upper and lower extremities. Reflexes are normal. ECG shows normal sinus rhythm. Which of the following is the most likely cause of this patient's symptoms?

Question

An 81-year-old man comes to the office due to dizziness and near falls.  The patient's daughter reports that, over the past 2 weeks, the patient has stated that he experiences intermittent lightheadedness and he sometimes "appears wobbly" and almost falls, most notably in the morning after getting out of bed.  Medical history is significant for hypertension and Alzheimer dementia.  He takes amlodipine and was recently started on quetiapine for aggressive behavior toward caregivers and delusions that his daughter has been cloned.  Temperature is 37 C (98.6 F), blood pressure is 105/66 mm Hg, and pulse is 95/min.  Pulse oximetry is 96% on room air.  The patient is awake, alert, and oriented to person and place.  Heart sounds are regular and without murmurs.  The lungs are clear to auscultation bilaterally.  Strength is 5/5 in the upper and lower extremities.  Reflexes are normal.  ECG shows normal sinus rhythm.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d193_bd92_bc81_ebe7fc8980c2_MD0003_00 This patient with near falls and dizziness after getting up from bed most likely experienced orthostatic syncope, which usually results from disruption of one or more components of the baroreceptor response. Standing from a seated or supine position normally causes a rapid drop in blood pressure that triggers an increase in sympathetic drive, causing vasoconstriction to increase peripheral resistance and increased heart rate and contractility to aid cardiac output. These changes facilitate a corrective increase in blood pressure to prevent a drop in cerebral perfusion and its associated symptoms (eg, lightheadedness, syncope). drop in blood pressure Certain medications can interfere with the normal baroreceptor response. This patient was recently given quetiapine for aggressive behavior and delusions; many antipsychotics, both first generation (eg, haloperidol) and second generation (eg, risperidone, quetiapine), have alpha-1 blocking properties that can cause or contribute to orthostatic syncope. With smooth muscle alpha-1 receptors blocked (on both capacitance veins and peripheral arterioles), vasoconstrictive sympathetic output is disrupted; therefore, on standing, blood cannot be mobilized from capacitance veins to increase venous return and systemic vascular resistance cannot be increased to help maintain blood pressure. Consequently, cardiac output and cerebral perfusion drop, and syncope can occur. Although this mechanism alone can result in orthostatic hypotension, patients taking other exacerbating medications (eg, other vasodilators such as amlodipine) are at even greater risk. (Choice A) Vasodilators increase (rather than decrease) venous capacitance (eg, pooling of blood), which impairs mobilization of blood back to the heart and can contribute to orthostatic hypotension and syncope. (Choices C and D) Medications that impair atrioventricular node conduction and/or myocardial contractility (eg, beta blockers) can disrupt the normal baroreceptor response and cause or contribute to orthostatic syncope. However, both amlodipine and quetiapine have no effect on atrioventricular node conduction or myocardial contractility. (Choice E) Neuroleptic malignant syndrome is a rare adverse effect of antipsychotics that involves fever, muscle rigidity, and autonomic dysfunction with blood pressure instability. It is unlikely to explain this patient's intermittent symptoms that are orthostatic in nature (ie, most prominent after getting out of bed in the morning). Educational objective: Certain medications can disrupt the normal baroreceptor response and cause or contribute to orthostatic syncope. Medications with alpha-1 receptor blocking properties (eg, quetiapine) are particularly common precipitants of orthostatic symptoms, and patients taking concomitant exacerbating medications (eg, other vasodilators) are at greater risk of experiencing symptoms. References: Minimizing cardiovascular adverse effects of atypical antipsychotic drugs in patients with schizophrenia. (http://www.ncbi.nlm.nih.gov/pubmed/24649390)

An 81-Year-Old Man Comes to the Office Due to Dizziness