From the Guidelines
Diastolic hypotension can be caused by several factors, including severe volume depletion, baroreflex dysfunction, autonomic insufficiency, and certain venodilator antihypertensive drugs, such as β-blockers and α-blockers 1. Other potential causes include diuretics and nitrates, which may further aggravate orthostatic hypotension 1. Additionally, decreased cardiac output secondary to myocardial ischemia or cardiac arrhythmias can also contribute to diastolic hypotension 1.
- Some key factors to consider when evaluating diastolic hypotension include:
- Volume depletion, which can be caused by various factors such as dehydration, blood loss, or certain medications 1
- Cardiac dysfunction, which can lead to decreased cardiac output and subsequent diastolic hypotension 1
- Vascular disease, which can affect blood flow and pressure regulation 1
- Medications, such as diuretics, β-blockers, and α-blockers, which can contribute to diastolic hypotension 1 It is essential to evaluate the underlying cause of diastolic hypotension and adjust treatment accordingly. In cases of symptomatic hypotension, consideration may be given to reducing or suspending antihypertensive medications, and in some cases, administering intravenous fluids or using medications like phenylephrine to increase blood pressure 1. Close monitoring of blood pressure and patient symptoms is crucial to determine the best course of action.
From the FDA Drug Label
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action Phenylephrine hydrochloride is an α-1 adrenergic receptor agonist. 12. 2 Pharmacodynamics Phenylephrine is the active moiety. Metabolites are inactive at both the α-1and α-2 adrenergic receptors. Following parenteral administration of phenylephrine hydrochloride, increases in systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and total peripheral vascular resistance are observed The onset of blood pressure increase following an intravenous bolus phenylephrine hydrochloride administration is rapid and the effect may persist for up to 20 minutes. As mean arterial pressure increases following parenteral doses, vagal activity also increases, resulting in reflex bradycardia. Most vascular beds are constricted, including renal, splanchnic, and hepatic.
The FDA drug label does not answer the question.
From the Research
Causes of Diastolic Hypotension
There are no direct causes of diastolic hypotension mentioned in the provided studies. However, the studies discuss the definition, diagnosis, and management of hypertension, which can be related to diastolic blood pressure.
Definition and Diagnosis of Hypertension
- Hypertension is defined as a persistent elevation in office systolic blood pressure ≥ 140 and/or diastolic blood pressure ≥ 90 mmHg 2
- The American College of Cardiology (ACC) and the American Heart Association (AHA) define hypertension as a blood pressure ≥ 130/80 mmHg 3
- Diastolic dysfunction is a predictor of heart failure, being involved in the association between hypertension and heart failure with preserved ejection fraction 4
Relationship Between Diastolic Blood Pressure and Hypertension
- Diastolic dysfunction is highly prevalent in hypertensive patients and is associated with increased cardiovascular morbidity and mortality 5
- Patients with prehypertension already show impaired cardiac relaxation before the onset of hypertension, as evidenced by a progressive decrease in e' velocity 4
- Isolated diastolic hypertension is underdiagnosed in clinical practice, and several patient-centered factors also strongly influence whether a diagnosis is made 6