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Could Pathophysiology Failure Be Ruled Out?

      To the Editor:
      I read with great interest the article by von Arx et al
      • Von Arx R.
      • Rexhaj E.
      • Allemann Y.
      • et al.
      Lack of blood pressure lowering effect of renal denervation in a drug-naive patient with pronounced arterial stiffening.
      published in the The American Journal of Medicine. Arx et al presented a case showing that renal denervation did not lower blood pressure in a drug-naïve patient and provided evidence that the nonresponsiveness of blood pressure to renal denervation may be due to arterial stiffness.
      One of the possible reasons for the nonresponsiveness of blood pressure to renal denervation is pathophysiology failure. Pathophysiology failure means that renal sympathetic activity does not increase in a hypertensive patient. Arx et al
      • Von Arx R.
      • Rexhaj E.
      • Allemann Y.
      • et al.
      Lack of blood pressure lowering effect of renal denervation in a drug-naive patient with pronounced arterial stiffening.
      stated that they ruled out this possibility because systolic blood pressure variability of this patient was decreased from 18.0 mm Hg at baseline to 12.6 mm Hg at 3 months after renal denervation. The decrease in systolic blood pressure variability may indicate that the renal denervation procedure was successful in this patient; however, it did not provide information on whether the baseline blood pressure variability was elevated compared with that in the age-matched normotensive population. Therefore, it is still possible that renal sympathetic activity did not increase in this patient and that pathophysiology failure may, in part, contribute to the nonresponsiveness of blood pressure to renal denervation in this patient.
      Systolic blood pressure variability, as von Arx et al
      • Von Arx R.
      • Rexhaj E.
      • Allemann Y.
      • et al.
      Lack of blood pressure lowering effect of renal denervation in a drug-naive patient with pronounced arterial stiffening.
      pointed out, has been reported to be correlated with muscle sympathetic nerve activity.
      • Narkiewicz K.
      • Winnicki M.
      • Schroeder K.
      • et al.
      Relationship between muscle sympathetic nerve activity and diurnal blood pressure profile.
      However, this correlation was observed in young normotensive subjects with a mean age of 31 years.
      • Narkiewicz K.
      • Winnicki M.
      • Schroeder K.
      • et al.
      Relationship between muscle sympathetic nerve activity and diurnal blood pressure profile.
      This young age is different from the mean age of patients undergoing renal denervation, which is approximately 60 years.
      • Krum H.
      • Schlaich M.
      • Whitbourn R.
      • et al.
      Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-principle cohort study.
      • Esler M.D.
      • Krum H.
      • Sobotka P.A.
      • et al.
      Renal sympathetic denervation in patients with treatment-resistant hypertension (The Symplicity HTN- 2 Trial): a randomised controlled trial.
      Therefore, the usefulness of systolic blood pressure variability as a proxy of sympathetic activity in the elderly population is still to be established.
      Therefore, it is possible that pathophysiology failure may, in part, contribute to the nonresponsiveness of blood pressure to renal denervation in this patient.

      References

        • Von Arx R.
        • Rexhaj E.
        • Allemann Y.
        • et al.
        Lack of blood pressure lowering effect of renal denervation in a drug-naive patient with pronounced arterial stiffening.
        Am J Med. 2014; 127: e3-e4
        • Narkiewicz K.
        • Winnicki M.
        • Schroeder K.
        • et al.
        Relationship between muscle sympathetic nerve activity and diurnal blood pressure profile.
        Hypertension. 2002; 39: 168-172
        • Krum H.
        • Schlaich M.
        • Whitbourn R.
        • et al.
        Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-principle cohort study.
        Lancet. 2009; 373: 1275-1281
        • Esler M.D.
        • Krum H.
        • Sobotka P.A.
        • et al.
        Renal sympathetic denervation in patients with treatment-resistant hypertension (The Symplicity HTN- 2 Trial): a randomised controlled trial.
        Lancet. 2010; 376: 1903-1909

      Linked Article

      • Lack of Blood Pressure-lowering Effect of Renal Denervation in a Drug-naïve Patient with Pronounced Arterial Stiffening
        The American Journal of MedicineVol. 127Issue 9
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          A 59-year-old man with the diagnosis of severe arterial hypertension was admitted to our clinic for hypertension treatment failure due to drug-related intolerable side effects (ie, nausea, dizziness, erectile dysfunction, and peripheral edemas). Additional cardiovascular risk factors were overweight, hypercholesterolemia, and a history of smoking. The medical history was otherwise unremarkable. Secondary causes of hypertension had been excluded by appropriate work-up.1 The patient had persistent, severe hypertension (average blood pressure of 177/102 mm Hg on 24-hour ambulatory blood pressure monitoring).
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      • The Reply
        The American Journal of MedicineVol. 127Issue 12
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          We thank Wang for his interesting comments1 on our case report.2 He suggests that a potential contributor for failure of renal denervation to lower blood pressure in our patient could be pathophysiologic failure (ie, renal sympathetic overactivity was not a major mechanism involved in hypertension).
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