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Article Buffering blood pressure fluctuations by respiratory sinus a...

Regards,

Joachim

A.G. Ramakrishnan

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Hello Ramakrishnan,

this phenomenon of continued heart rate oscillations at roughly the respiratory rate, even at breath hold, has been observer earlier (of course, almost nothing new in Physiology if you search well). I have read the papers involved, but cannot find them in my collection, I must have lost them

The author is Jan Penaz (the later inventor of the Finapres), working at the time (around 1960) in Leiden, The Netherlands. The papers appeared in the J. Physiol (Paris) in French.

I hope this helps.

Regards,

John M. Karemaker

1)

J Physiol (Paris) Jan-Mar 1957;49(1):346-9.

[Oscillations of the cardiac frequency and of the vasomotor tonus during slowed and accelerated respiration]

J Penaz

[Article in French]

PMID: 13449839

2)

J Physiol (Paris) 1958 Mar;50(2):443-6.

[Chronological relations in circulatory oscillations of the third order in man]

J Penaz

[Article in French]

PMID: 13550198

3)

J Physiol (Paris) Sep-Oct 1965;57(5):673.

[The oscillatory nature of vascular resistance reactions]

J Penaz, P Burianek, B Semrad

[Article in French]

PMID: 5847146

Thanks a lot, Prof. John Karemaker. I shall look into these papers. I love your statement, "There is almost nothing new in physiology if you search well." Hope these papers answer all my questions.

Dear Prof. Karemaker,

may these oscillations be related with a mechanical modulation of the heart?

Is the amplitude of these oscillations comparable to normal respiratory sinus arrhythmia patterns?

Bernardi and colleagues found heart rate fluctuations synchronous with respiration in denervated hearts.

https://pubmed.ncbi.nlm.nih.gov/2097063/

Article Respiratory sinus arrhythmia in the denervated heart

As well, our group observed that during atrial flutter a respiratory modulation in both atrial and ventricular beat intervals is present, which is due to a periodic variation of atrial volume/pressure related to respiration mechanics.

https://pubmed.ncbi.nlm.nih.gov/19023018/

Article Mechanical modulation of atrial flutter cycle length

Hoping that this information can be of any interest for you, I send my best regards,

Michela

Dear Michela,

Thank you for your reply. About RSA in the absence of respiratory movements, one should consult the beautiful experiments from Robin McAllens’ lab (e.g. Brainstem sources of cardiac vagal tone and respiratory sinus arrhythmia in J Physiol 594.24 (2016) pp 7249–7265, DOI: 10.1113/JP273164). They show RSA without any movement (of course not, in their rat working heart-brainstem preparation). So, a central component of RSA at the normal rate during breath hold is quite understandable. On the other hand: the mechanical effects of cardiac filling with respiration can modulate the sinus node (stretch, in the denervated heart) or via the baroreflex, in the not-denervated heart.

This is my simplistic view on the phenomena that you describe,

Regards,

John M. Karemaker

Hi A.G. Ramakrishnan I think your data is very interesting and worth publishing. Do you have beat to beat BP or just ECG and respiration? and what do you have for respiration, belt (chest movement) or air flow? what about ETCO2? Can you tell us more about the study design? how long was the breath hold and at which phase (end inspiration, end expiration)? was the breath hold like Valsalva manoeuvre or without force? was the breath hold always after slow breathing? was it slow breathing or slow AND deep breathing? You maybe interested to read our study on the effect of load during slow and deep breathing

Article Influence of inspiratory threshold load on cardiovascular re...

Dear Prof. Ali Gholamrezaei,

Thanks for your reply. Our earlier conference papers on this observation are: Conference Paper R-wave Amplitude Changes and Atypical Heart Rate Changes Acc...

and Conference Paper Anomaly in respiratory sinus arrhythmia - multiple heart rat...

Subsequently, we have recorded on many more subjects. All of them are symmetric, slow and deep breathing, once without any hold and once again with hold after both inhalation and exhalation - for 2 minutes at each breathing rate - 10, 6, 4 and 2 per minute. In the recent recordings, we have recorded ECG, EEG, belt-based respiration. No BP or CO2. No Valsalva; It is just hold without any force, with the durations synchronized to a visual metronome.

A.G. Ramakrishnan thanks for the details. Difficult to understand the mechanisms just by having ECG. We need beat to beat BP (can estimate SV too) and even better cardiac imaging (doppler ultrasound or MRI) to understand the mechanical modulations. Note that the mechanical modulation from respiration on BP and heart (and blood return) has some immediate effects but also some effects with delay as it takes few heartbeats for the returned blood to the right heart chamber to go to the left heart chamber. So what you see during breath-hold right after a deep inspiration or expiration can still be due to, at least in part, the previous breathing cycle. In order to see what happens during breath holding not as a result of respiration I think you need much longer breath holds, like for example 1 minute just holding the breath, so there is enough time to get rid of the effects of the previous breathing cycle, although then PCO2 increases and stimulates chemoreceptors and ... so difficult to isolate these mechanisms in human studies. If you can visualize some of your data (respiration + HR) I can better comment.

Hi, I just located a good reference to the work of Jan Penaz, togethet with Burianek. This paper is simply accessible on the Net:

Peňáz, J., Buriánek, P., 1963. Zeitverlauf und Dynamik der durch Atmung ausgelösten Kreislaufänderungen beim Menschen. Pflüger's Archiv für die gesamte Physiologie des Menschen und der Tiere 276, 618-635. DOI: 10.1007/BF00363567

Yes, in German this one, but that is Pflúgers for you.

They did experiments with breath hold and non-invasive blood pressure recording (remember that Jan Penaz later invented and he and Karel Wesseling together developed what has become famous as the Finapres). The pictures are very clear, even if you don't understand German.

They convincingly show that there are underlying strong blood pressure oscillations at a rate of about 0.1 Hz during breath hold.

This should answer a lot of questions,

John M. Karemaker

I would guess this is related to resonance phenomena in the baroreflex. Take a look at Evgeny and Bronya Vaschillo’s work. For a good review: G. Vaschillo E., Vaschillo B., F. Buckman J., E. Bates M. and J. Pandina R. (2010).

RESONANCES IN THE CARDIOVASCULAR SYSTEM - Investigation and Clinical Applications.

In Proceedings of the Third International Conference on Bio-inspired Systems and Signal Processing, pages 21-28

DOI: 10.5220/0002691200210028

I wonder (1) at what frequency are these oscillations occurring and (2) whether they are related to individual differences in respiratory frequency among the research participants, or (3) whether they either are more uniformly occurring at a single frequency within the respiratory range across all subjects or (4) just below it (the well documented 0.10-Hz component ( roughly. 6 cycles/minute). (5) Also I wonder how large the oscillations are and whether they really are similar in magnitude to what occurs at these frequencies during spontaneous breathing.

The voluntary breath holding does not prevent respiratory centers to work and their activity continues to gate vagal cardiac motoneurone responsiveness and, in turn, heart rate (DL Eckberg, J Physiol, 548.2, 339-352, 2003)