PPG Advanced API

PPG Advanced provides blood pressure estimation and vascular health assessment based on ECG + PPG fusion analysis.

Subscription requirement

The PPG Advanced API requires an Advanced subscription. View pricing

Data requirements

PPG Advanced analysis requires you to provide both ECG and PPG data to improve accuracy.

Blood pressure estimation

POST /api/v1/advanced/ppg/blood-pressure

Based on fusion analysis of ECG and PPG signals, estimate blood pressure values (systolic and diastolic).

Important

Blood pressure estimation is for reference only. It cannot replace a medical blood pressure monitor and is not a medical diagnosis.

Request parameters

Parameter	Type	Required	Description
ecgData	array	✅	ECG signal data array
ecgSampleRate	number	✅	ECG sampling rate (Hz)
adcGain	number	❌	Gain coefficient (default: 1.0)
adcZero	number	❌	Zero/baseline voltage (default: 0.0)
ppgData	object	✅	PPG signal data object
ppgSampleRate	number	✅	PPG sampling rate (Hz)

`ppgData` object structure

Field	Type	Required	Description
red	array	✅	Red light PPG data array
green	array	✅	Green light PPG data array
infrared	array	✅	Infrared PPG data array

PPG multi-channel data

To estimate blood pressure accurately, provide red, green, and infrared PPG channels at the same time.

Request example

curl -X POST "https://api.heartvoice.com.cn/api/v1/advanced/ppg/blood-pressure" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "ecgData": [512, 515, 520, 518, 525, ...],
    "ecgSampleRate": 500,
    "adcGain": 1.0,
    "adcZero": 0.0,
    "ppgData": {
      "red": [1024, 1028, 1032, ...],
      "green": [2048, 2052, 2056, ...],
      "infrared": [1536, 1540, 1544, ...]
    },
    "ppgSampleRate": 100
  }'

Response example

{
  "errorCode": "0",
  "msg": "success",
  "data": {
    "sqGrade": "0.95",
    "sbp": 124,
    "dbp": 68
  }
}

Response fields

Field	Type	Description	Unit	Normal range
sqGrade	string	Signal quality grade (details)	-	-
sbp	number	Systolic blood pressure	mmHg	90–120
dbp	number	Diastolic blood pressure	mmHg	60–80

Blood pressure classification standards

Category	Systolic (mmHg)	Diastolic (mmHg)
Normal	< 120	< 80
Elevated	120–129	< 80
Hypertension Stage 1	130–139	80–89
Hypertension Stage 2	≥ 140	≥ 90

Recommendations

Sit quietly during measurement; keep your arm at the same level as your heart
Avoid measuring immediately after exercise, eating, or drinking alcohol
Measure multiple times and take the average value
Calibrate regularly with a standard blood pressure monitor

Vascular health assessment

POST /api/v1/advanced/ppg/vascular-health

Analyze vascular elasticity from ECG and PPG signals to assess vascular age.

Request parameters

Parameter	Type	Required	Description
ecgData	array	✅	ECG signal data array
ecgSampleRate	number	✅	ECG sampling rate (Hz)
adcGain	number	❌	Gain coefficient (default: 1.0)
adcZero	number	❌	Zero/baseline voltage (default: 0.0)
ppgData	object	✅	PPG signal data object
ppgSampleRate	number	✅	PPG sampling rate (Hz)

`ppgData` object structure

Field	Type	Required	Description
red	array	✅	Red light PPG data array
green	array	✅	Green light PPG data array
infrared	array	✅	Infrared PPG data array

Request example

curl -X POST "https://api.heartvoice.com.cn/api/v1/advanced/ppg/vascular-health" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "ecgData": [512, 515, 520, 518, 525, ...],
    "ecgSampleRate": 500,
    "adcGain": 1.0,
    "adcZero": 0.0,
    "ppgData": {
      "red": [1024, 1028, 1032, ...],
      "green": [2048, 2052, 2056, ...],
      "infrared": [1536, 1540, 1544, ...]
    },
    "ppgSampleRate": 100
  }'

Response example

{
  "errorCode": "0",
  "msg": "success",
  "data": {
    "sqGrade": "0.95",
    "vascularAge": 61
  }
}

Response fields

Field	Type	Description	Unit
sqGrade	string	Signal quality grade (details)	-
vascularAge	number	Vascular age	years

How to interpret vascular age

Difference vs. actual age	Assessment	Recommendation
Diff <= -5 years	Excellent	Very good vascular elasticity—keep it up
-5 < Diff <= 0 years	Good	Healthy vascular status
0 < Diff <= 5 years	Fair	Pay attention to vascular care
5 < Diff <= 10 years	Deviation	Improve lifestyle
Diff > 10 years	Poor	Consider medical evaluation

Factors affecting vascular age

Smoking and alcohol consumption
Hypertension and hyperlipidemia
Lack of exercise
Unhealthy diet habits
Long-term late nights and high stress

Recommendations

Quit smoking and limit alcohol
Do moderate aerobic exercise (3–5 times/week, 30 minutes each time)
Eat more fresh fruits/vegetables and reduce high-fat/high-salt foods
Maintain healthy daily routines
Have regular health checkups

Technical principles

Blood pressure estimation principle

Blood pressure estimation is based on the following physiological principles and technical methods:

Pulse Transit Time (PTT)
- Uses the time difference between the ECG R-peak and the PPG pulse peak
- PTT is negatively correlated with blood pressure
- Formula: PTT = PPG peak time - ECG R-peak time
PPG waveform features
- Rising slope (reflects vascular elasticity)
- Peak amplitude (reflects blood flow volume)
- Waveform area (reflects per-beat output)
- Reflected wave characteristics (reflects peripheral resistance)
Multi-channel fusion
- Red light: superficial skin blood flow
- Green light: advantages for heart rate detection
- Infrared: deeper tissue penetration
Deep learning model
- AI models combining multi-dimensional features
- Trained on large-scale clinical data

Vascular age assessment principle

Vascular elasticity is assessed based on:

Pulse Wave Velocity (PWV)
- Uses PTT and the known arterial path length
- Faster PWV indicates stiffer vessels
Augmentation Index (AI)
- Analyzes reflected waves in the PPG waveform
- Reflects large-artery stiffness
Waveform morphology analysis
- Rise time
- Peak time
- Diastolic-phase waveform

Data requirements

Signal duration

Analysis type	Minimum duration	Recommended duration
Blood pressure estimation	10 seconds	30 seconds
Vascular health assessment	10 seconds	30 seconds

Sampling rate requirements

Signal type	Minimum sampling rate	Recommended sampling rate
ECG	250Hz	500Hz
PPG	50Hz	100Hz

Measurement conditions

To ensure accuracy, please note:

✅ Correct measurement posture

Sit and rest for 5 minutes before measuring
Keep your arm relaxed naturally and at the same level as your heart
Avoid talking and moving

✅ Appropriate environment

Suitable room temperature (20–25°C)
Avoid strong direct light shining on the sensor
Keep quiet

❌ Avoid the following

Measure immediately after vigorous exercise
Measure within 30 minutes after eating, drinking alcohol, or smoking
When you are emotionally excited/overwhelmed
Cold fingers or sweaty hands

Frequently asked questions

Q: Why do we need to provide both ECG and PPG data?

A:

Blood pressure and vascular health assessments rely on PTT calculation, which requires the ECG R-peak time and the PPG pulse peak time. PPG alone cannot provide an accurate PTT value.

Q: What is the purpose of three PPG channels?

A:

Red (660nm): Detects superficial skin blood flow for blood pressure estimation
Green (520nm): Most accurate for heart rate detection and used for PTT calculation
Infrared (940nm): Deep penetration for vascular state assessment

Q: Are the estimated blood pressure values accurate?

A:

The accuracy of blood pressure estimation is affected by multiple factors:

Under ideal measurement conditions, the error is typically within ±5–10 mmHg
For first-time use, we recommend calibrating against a standard blood pressure monitor
For reference only; cannot replace a medical blood pressure monitor
Not intended for medical diagnosis

Q: How often is it appropriate to measure?

A:

Daily monitoring: 1–2 times per day (morning and evening)
If blood pressure is abnormal: follow your clinician’s advice; you may need more frequent monitoring
For healthy people: 2–3 times per week is usually sufficient

Next steps

ECG Basic API - ECG basic analysis
ECG Advanced API - ECG advanced features
Authentication - Get API Key
Usage examples - Complete integration example

Blood pressure estimation​

POST /api/v1/advanced/ppg/blood-pressure​

Request parameters​

ppgData object structure​

Request example​

Response example​

Response fields​

Vascular health assessment​

POST /api/v1/advanced/ppg/vascular-health​

Request parameters​

ppgData object structure​

Request example​

Response example​

Response fields​

Technical principles​

Blood pressure estimation principle​

Vascular age assessment principle​

Data requirements​

Signal duration​

Sampling rate requirements​

Measurement conditions​

Frequently asked questions​

Q: Why do we need to provide both ECG and PPG data?​

A:​

Q: What is the purpose of three PPG channels?​

A:​

Q: Are the estimated blood pressure values accurate?​

A:​

Q: How often is it appropriate to measure?​

A:​

Next steps​

Blood pressure estimation

POST /api/v1/advanced/ppg/blood-pressure

Request parameters

`ppgData` object structure

Request example

Response example

Response fields

Vascular health assessment

POST /api/v1/advanced/ppg/vascular-health

Request parameters

`ppgData` object structure

Request example

Response example

Response fields

Technical principles

Blood pressure estimation principle

Vascular age assessment principle

Data requirements

Signal duration

Sampling rate requirements

Measurement conditions

Frequently asked questions

Q: Why do we need to provide both ECG and PPG data?

A:

Q: What is the purpose of three PPG channels?

A:

Q: Are the estimated blood pressure values accurate?

A:

Q: How often is it appropriate to measure?

A:

Next steps