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Effective end-organ peripheral vascular resistance responses are critical to blood pressure control while upright, and prevention of syncope (fainting). The Valsalva maneuver (VM) induces blood pressure decreases that evoke baroreflex-mediated vasoconstriction. We characterized beat-to-beat forearm vascular resistance (FVR) responses to the VM in healthy adults, evaluated the impact of age and sex on these responses, and investigated their association with orthostatic tolerance (OT; susceptibility to syncope). We hypothesized that individuals with smaller FVR responses would be more susceptible to syncope. Healthy young (N = 36; 19 women; age 25.4 ± 4.6 years) and older (N = 21; 12 women; age 62.4 ± 9.6 years) adults performed a supine 40 mmHg, 20 s VM. Graded 60° head-up-tilt with combined lower body negative pressure continued to presyncope was used to determine OT. Non-invasive beat-to-beat blood pressure and heart rate (finger plethysmography) were recorded continuously. FVR was calculated as mean arterial pressure (MAP) divided by brachial blood flow velocity (Doppler ultrasound) relative to baseline. The VM produces a distinctive FVR pattern that peaks (+137.1 ± 11.6%) in phase 2B (17.5 ± 0.3 s) as the baroreflex responds to low-pressure perturbations. This response increased with age overall (p

A critical step in the clinical evaluation of postural tachycardia syndrome (PoTS) is the assessment of orthostatic tachycardia. Active stand testing (AST) and head up tilt table testing (HUT) can both be used to evaluate the presence of this tachycardia. Drugs that affect heart rate (HR), sympathetic nervous system activity, or blood volume should be withheld prior to the orthostatic test. There are several important methodological and physiological differences with HUT versus AST. Orthostatic heart rate is typically higher during HUT than with AST, and requires specialized equipment that is not available to all clinicians. Conversely, AST is convenient, cost-effective and can be performed in the primary care physician office. Reflex tachycardia specific to initial orthostatic hypotension may be greater in the initial minutes of AST, compared to HUT, and this should be considered in the evaluation of early AST HR responses. The AST has similar sensitivity and greater specificity than HUT. Overall, AST should be used as the first line diagnostic tool during assessment of orthostatic tachycardia in PoTS.

A diagnosis of Postural Tachycardia Syndrome (PoTS) requires a sustained increase in heart rate of 30 beats per minute or more (40 beats per minute if age 12–19 years) within 10 minutes of assuming upright posture, and in the absence of orthostatic hypotension (

Background Cardiovascular autonomic dysfunction is an early marker for cardiovascular disease. Anthracycline chemotherapy and left-sided radiation for breast cancer are associated with negative autonomic function changes. This study's objectives were to characterize changes in, and the association of exercise training with, clinical indices of cardiovascular autonomic function across the trajectory of breast cancer therapy. Subjects, Materials, and Methods Seventy-three patients receiving adjuvant chemotherapy participated to varying degrees in supervised aerobic and resistance exercise during chemotherapy ± radiation and for 20 weeks after. Resting heart rate (HRrest) and blood pressure were measured weekly during chemotherapy. HRrest, exercise heart rate recovery (HRrecovery), and aerobic fitness were measured at enrollment, end of chemotherapy ± radiation, and 10 and 20 weeks after treatment. Results During chemotherapy, HRrest increased in a parabolic manner within a single treatment and with increasing treatment dose, whereas systolic and diastolic blood pressure decreased linearly across treatments. Tachycardia and hypotension were present in 32%–51% of participants. Factors associated with weekly changes during chemotherapy included receiving anthracyclines or trastuzumab, days since last treatment, hematocrit, and exercise attendance. Receipt of anthracyclines, trastuzumab, and left-sided radiation individually predicted impairments of HRrest and HRrecovery during chemotherapy ± radiation; however, aerobic fitness change and at least twice-weekly exercise attendance predicted improvement. By 10 weeks after treatment, HRrest and blood pressure were not different from prechemotherapy. Conclusion In this study, chemotherapy resulted in increased HRrest and tachycardia, as well as decreased blood pressure and hypotension. Anthracyclines, trastuzumab, and left-sided radiation were associated with HRrest elevations and impairments of HRrecovery, but exercise training at least twice a week appeared to mitigate these changes. Implications for Practice This study characterized changes in clinically accessible measures with well-established prognostic value for cardiovascular disease, and investigated associations with cardiotoxic treatments and the positive influence of exercise. The chemotherapy-related incremental increase in resting heart rate, with tachycardia occurring in one third of patients, and decrease in blood pressure, with hypotension occurring in one half of the patients, is relevant to oncology practitioners for clinical examination or patient report of related symptoms (i.e., dizziness). The weekly dose of two 60-minute sessions of moderate-intensity aerobic and resistance exercise that was identified as protective of cardiovascular autonomic impairments can easily be prescribed to patients by oncologists.

We read with interest the paper by Thibodeau et al. [(1)][1] describing the role of the clinical examination in patients with heart failure. Zema [(2)][2] should also be commended for his letter emphasizing the role of the Valsalva maneuver in the diagnosis of heart failure. We regularly perform

The arterial baroreflex is crucial for short‐term blood pressure control – abnormal baroreflex function predisposes to syncope and falling. Hypersensitive responses to carotid baroreflex stimulation using carotid sinus massage (CSM) are common in older adults and may be associated with syncope. The pathophysiology of this hypersensitivity is unknown, but chronic denervation of the sternocleidomastoid muscles is common in elderly patients with carotid sinus hypersensitivity (CSH), and is proposed to interfere with normal integration of afferent firing from the carotid baroreceptors with proprioceptive feedback from the sternocleidomastoids, producing large responses to CSM. We hypothesized that simulation of sternocleidomastoid “denervation” using pharmacological blockade would increase cardiovascular responses to CSM. Thirteen participants received supine and tilted CSM prior to intramuscular injections (6–8 mL distributed over four sites) of 2% lidocaine hydrochloride, and 0.9% saline (placebo) in contralateral sternocleidomastoid muscles. Muscle activation was recorded with electromyography (EMG) during maximal unilateral sternocleidomastoid contraction both pre‐ and postinjection. Supine and tilted CSM were repeated following injections and responses compared to preinjection. Following lidocaine injection, the muscle activation fell to 23 ± 0.04% of the preinjection value (P 0.05). Neural block of the sternocleidomastoid muscles does not increase cardiovascular responses to CSM. The pathophysiology of CSH remains unknown.