Valsalva Maneuver

Anatomy and Physiology

Based on the characteristic hemodynamic changes, the Valsalva maneuver divides into four phases.

Phase I, which corresponds to the onset of strain, is associated with a transient rise in blood pressure because of the emptying of some blood from the large veins and pulmonary circulation.

Phase II follows this when positive intrathoracic pressure leads to a reduced venous return to the heart. Because of reduced venous return and thus reduced preload, stroke volume falls; this leads to a fall in blood pressure activating the baroreceptors in the carotid sinus and aortic arch. The vagal withdrawal followed by increased sympathetic discharge ensues, leading to marked tachycardia, increased cardiac output, and vasoconstriction, which leads to the recovery of blood pressure to normal values in healthy individuals.

Phase III is the transient phase involving the release of strain which leads to a sudden dip in blood pressure. The release of positive pressure leads to expansion of the pulmonary vascular bed and reduces the left ventricular cross-sectional area resulting in a transient fall in blood pressure.[6]

Phase IV is the overshoot of the blood pressure above the baseline, which is because of the resumption of normal venous return to the heart stimulated by the sympathetic nervous system during Phase II. The overshoot of blood pressure leads to stimulation of baroreflex, leading to bradycardia and the return of blood pressure to the baseline.[4][7]

Indications

Valsalva maneuver is used for assessment of autonomic function status, as a marker for heart failure, for termination of arrhythmias, murmur differentiation, and various other indications.

Contraindications

Valsalva maneuver is relatively safe and can be performed in all patients. Side effects reported are rare. However, since there is a rise in intraocular and intra-abdominal pressure, therefore the test must be avoided in patients with retinopathy and intraocular lens implantation. Valsalva retinopathy may result in susceptible patients.[8][9] Also, there are reports of syncope, chest pain, and arrhythmias due to the performance of VM. Therefore, caution is necessary for patients with pre-existing coronary artery disease, valvular disease, or congenital heart disease.[1][2]

Equipment

A modification of this maneuver can be performed in the cardiovascular laboratory or at the bedside using a disposable syringe/mouthpiece connected to a manometer. A small leak is created in the syringe/mouthpiece to ensure sustained effort throughout the period of forced exhalation.[10] Adequacy of the expiratory effort can be gauged by subjective signs such as visible strain, flushing, and engorgement of the neck veins.[1] Simultaneous acquisition of the electrocardiogram (ECG) signal can help us to assess autonomic indices, such as the Valsalva ratio. Measurement of continuous beat-to-beat blood pressure can help in testing baroreflex sensitivity.

Technique or Treatment

The patient can perform the maneuver in the sitting, supine, or recumbent position. Some reports advocate a recumbent position,[10] while others report an increased incidence of abnormal blood pressure responses in the supine position.[11] While different combinations of pressure and duration have been tried, an optimal combination for autonomic function assessment is 40 mm Hg for 15 seconds. Lower pressures may not be sufficient, while higher pressures suffer from poor reproducibility.[10]

Modified VM

In order to increase the relaxation phase venous return and vagal stimulation, a modification to the standard VM has been described in the REVERT trial, which includes supine positioning with leg elevation immediately after the Valsalva strain. This is used for the emergency treatment of supraventricular tachycardias.[12]

Reverse VM

The patient in a sitting position is asked to inhale against resistance for ten seconds while keeping the nose pinched and having the mouth closed tightly. This leads to increased vagal tone and decreased sympathetic activity, which in turn leads to bradycardia and arterial hypotension (the Bezold–Jarich reflex), causing supraventricular tachycardia to resolve in the next 15 seconds if effective.[13]

Clinical Significance

Autonomic function assessment: Valsalva maneuver is an integral part of the Ewing battery of tests used for the evaluation of cardiac autonomic neuropathy.[8] Valsalva ratio, the ratio of the longest inter-beat (RR) interval after the expiratory strain and the shortest inter-beat interval during the strain, is an index of parasympathetic function. Also, determination of baroreflex sensitivity (BRS) can be performed using the Valsalva maneuver to assess the integrity of the baroreflex by estimating the slope of a regression plot between RR intervals and systolic blood pressure values during phases II and IV of the maneuver.[9][10][11][14]

Assessment of heart failure: VM is useful for the assessment of heart failure. Patients with heart failure show an abnormal blood pressure overshoot in response to the Valsalva maneuver due to impaired ventricular function.[15]

Termination of Arrhythmias: VM is also useful for the termination of paroxysmal supraventricular tachycardia (PSVT) with variable success. Increased vagal activity, leading to increased refractoriness of atrioventricular (AV) nodal tissue interrupting re-entry, has been proposed as the mechanism for the termination of PSVT.[16]

Diagnosis of murmurs: VM may be used to differentiate between different murmurs. Since the maneuver reduces preload and thus end-diastolic volume, it can help accentuate some murmurs while diminishing others. The murmur of aortic stenosis (AS) is reduced in intensity on the administration of VM because reduced end-diastolic volume (EDV) diminishes the blood available for ejection through the stenosed aortic orifice.[17] Contrary to AS, the murmur of hypertrophic obstructive cardiomyopathy (HOCM) accentuates in response to VM because reduced EDV during VM leads to the worsening of the obstruction in hypertrophic obstructive cardiomyopathy.[17][18][19]

To detect bleeding points towards the end of thyroid surgery and for the diagnosis of varicocele.

To assist in the radiological diagnosis of liver hemangiomas,[14] venous disease,[15] and foramen ovale.[16]

To confirm hemostasis and absence of cerebrospinal fluid leak after neurosurgical procedures.

To reduce venipuncture pain in pregnant women.[20]

Enhancing Healthcare Team Outcomes

Valsalva maneuver (VM) is a simple, non-invasive test that can be easily performed using a mouthpiece and a manometer. While the maneuver is relatively safe, it is prudent to rule out any pre-existing disease of the retina before performing the maneuver. Therefore, one should consult an ophthalmologist and seek a thorough examination of the fundus in patients with suspected retinopathy. Similarly, the opinion of a cardiologist may assist in patients with pre-existing ischemic or valvular heart disease before the performance of VM.

It can assist the neurologist to identify patients suffering from autonomic neuropathy. Dysautonomia usually manifests as an absence of blood pressure overshoot and reflex bradycardia after the maneuver.[10] Valsalva ratio, assessed using inter-beat intervals during and post the maneuver, is a marker of parasympathetic reactivity. A value of less than 1.21 is considered abnormal,[17] but recently proposed age-specific cutoffs may be more relevant.[18][19] Also, beat-to-beat blood pressure and heart rate can be used to evaluate the integrity of the baroreflex arc by computation of baroreflex sensitivity. The maneuver may be useful to the cardiologist as it may help diagnose heart diseases based on the accentuation or diminution of murmur intensity. To sum up, this simple maneuver may give insight into underlying physiological functions as well as serve as a diagnostic and therapeutic modality in the laboratory and clinics.