Neuromodulation

Question 1

Types of Neuromodulation for HTN

Answer 1

Carotid Sinus Stimulation (CSS)
Carotid Body Ablation 
Renal Sympathetic Nerve Ablation
DBS
Microvascular rVLM Decompression

Question 2

CSS in HTN- studies

Answer 2

Rabbits (Douglas)
- Reduction in BP

HTNive Dogs (Schwartz)

• Greater reduction in BP for HTNive vs normal dogs
• Bilateral > unilateral

Humans

• Rheos device
• Reduction in BP

Question 3

Carotid Body Ablation (HTN)

Answer 3

CIH Rats (Rodrigo):
- Normalisation of BP, HR and Autonomic function

McBryde:

• Reduced T cell infiltration to carotid body (Angiotensin II)
• Reduced RSNA
• Reduction in inflammatory markers
• Synergistic effects when combined with Renal sympathetic ablation

Question 4

Renal Sympathetic Nerve Ablation (HTN)

Answer 4

Renal SNA in HTN:
Increased RAAS activation, noradrenergic excess

SYMPLICITY HTN-2: Radiofemoral catheter, reduced BP across 1,3, and 6 months

SYMPLICITY HTN-3: failed to meet primary outcome demonstrating benefit- no change in BP- could be different ablations, medication changes

Brandt: May also be a treatment for LVH
-LV thickness reduced after RSNA, increased LVEF and end-systolic volume

Question 5

Deep Brain Stimulation (HTN)

Answer 5

O’Callaghan: Anecdotal HTNive patient on DBS for chronic pain relief

Ventral PAG stimulation reduced BP and TPR (increased brachial blood flow)

Connections from ventral PAG to NTS and rVLM may mediate this

Question 6

Microvascular rVLM decompression (HTN)

Answer 6

Morimoto:
Treatment used for depression
Found to reduce BP, MSNA, plasma noradrenaline and renin

Question 7

Neuromodulation for Heart Failure

Answer 7

Carotid Sinus Stimulation
Vagus Nerve Stimulation (VNS)
Transcutaneous VNS

Question 8

Autonomic basis of Heart failure

Answer 8

Sympathetic upregulation

Parasympathetic withdrawal

Question 9

Carotid Sinus Stimulation (CHF)

Answer 9

Dogs (Sabbah)
-Improved LVEF, reduced myocyte fibrosis, improved haemodynamic stability

Human Trials: Barostim Neo
QoL and exercise capacity improvements
-Reduction in MSNA

Bisognano:Reversal of myocyte remodelling (reduced LV mass)

Question 10

VNS (CHF)

Answer 10

Li: MI induced rats

• Reduced LV mass
• Reduced NA and BNP
• No change in size of infarct

Lerner: MI-induced dogs
-Preservation of Cx43 gap junction protein, known to be decreased in ischaemia/CHF

Fast ventricular-paced dogs (Zhang)
- Reduction in NA, CRP, BNP, improved BRS, reduced RAAS activation

Humans: DeFerrari-
Improved heart-rate variability, Reduction in NYHA classification in some patients, exercise tolerance

ANTHEM-HF: improved QoL in patients

INOVATE-HF/NECTAR-HF: no proven benefit

Question 11

tVNS (CHF):

Answer 11

Dogs: improvement of ventricular function (reduced infarct size, LV dilatation)

Humans: improved MSNA, QoL, exercise tolerance, HR Variability
Reduced acute heart failure in CABG patients
Reduced angina attacks