**4. Animal heart experiments**

*Noise and Vibration Control - From Theory to Practice*

group [1]. We explain mDFA in the later section.

**2. Physiology of animal heart**

fluctuating.

the study, we use an analytical method, mDFA, which is recently developed by our

Circulation failure is absolutely a life-threatening event. Unpredictable cessation of blood flow is the worst-case scenario. For studying the problems, we need physiology, and it is necessary to record heartbeat data from freely moving animals. **Figure 1** shows how to record electrocardiogram (EKG) from invertebrate animals. Two permanently implanted metallic electrodes (+ and −), touching the surface of the heart with extreme caution, were used to record EKG. We used DAM50 C-R coupled AC amplifier (World Precision Instruments, USA) and Power

Nervous regulation of the crustacean heart is well documented by great scholars [1]: Carlson (1904), Alexandrowicz (1932), Maynard (1961), and so forth. The heart receives two kinds of nerve fibers. One is acceleratory nerve (CA) and the other is inhibitory nerve (CI) [3]. The nerves are always active and discharge frequency is ever-changing. Moreover, the brain releases slowly functioning cardio-active substances (peptide) via the nonneuronal hormonal method [6]. As a result, the heart never beats at a steady pace. Heart rate exhibits a dynamic change all through life. Heartbeat interval time is never stable, never regular, and is always

Mechanisms of cessation of heartbeat could be studied by mathematical methods. We believed that the method might be the frequency analysis because heartbeat is a cyclic behavior. The other candidate method is heartbeat-interval time series analysis. Whichever, we need natural data, EKG. We prepared two specimens,

*Diagrammatic representation for EKG recording from insect (A), lobster (B), and isopod crustacean Ligia (C).*

Lab (ADIntrument, Australia) for digital EKG data sampling at 1 kHz.

**34**

**Figure 1.**

**3. Analysis of heartbeat**

At a very early stage of the study, we learned that mDFA well distinguishes between intact and isolated hearts as aforementioned. We got an idea: mDFA can be a helpful tool in pathophysiology, because cardiac disease is one of the major causes of death worldwide.

We began to record long-term EKGs from model animals. The recordings were started from fresh healthy specimens and were kept continued to the end of their life. Sometimes, the recording period length exceeded 2 years, which is extremely long and painstaking (**Figure 1B**, lobster). In turn, it was, at one time, only 2 h (**Figure 1C**, isopod Crustacea).

**Figures 2** and **3** show example EKGs at terminal conditions.

**Figure 2** shows coconut crab EKG. This specimen was captured in March at a Japanese tropical island, south-west Okinawa. We transfer it to Tokyo in a handcarried baggage. Long-term EKG was recorded in Tokyo instead of the south, tropical zone. The animal eats apples and dry fish meat and lived longer than we expected. Climate in Tokyo got colder in autumn and the tropical crab ended its life in October: non-air-conditioned environment at natural room temperature. SI values in March were ~1.0 (data not shown). The SI values (around 0.9) continued to September.

In **Figure 2**, one can see that SI values decrease when dying. It is of interest that after the cessation of pumping heartbeat, fibrillation remained (**Figure 2**), which indicates that heart muscles still try to contract.

Many other specimens tested, including crayfish, crabs, insects, and clams, show a SI-decrease-phenomenon when dying (data not shown). We found it typical that when dying, animals show diminished movements and decremental SI-shift toward 0.5.

At the terminal condition, the brain is not likely to regulate the heart any longer, although the heart is still pumping like the isolated heart. We consider that the terminal condition accompanied by a low SI is a state of brain death.

If we look at dying crab specimens, our intuition tells that relevant specimen is likely to pass away soon. We define this as "natural death."

In the meantime, we encountered an unforgettable specimen that died unpredictably (**Figure 3**). At time zero in **Figure 3**, EKG trace looks normal. After checking EKG on PC screen, an author (TY) left Tokyo, setting out on a journey to see a hospitalized family. Two days later, TY returned and looked at PC and discovered that the crab

#### **Figure 2.**

*A long-term EKG from coconut crab (Birgus latro) with state space representation. Recording for 18 h. Inset: SI values for the corresponding period from (A) to (F). Note: fibrillation after beating stops. State space representation of cardiac action potentials shows a normal action potential shape in (A), gradually changing to distorted pattern (B, E, F), and finally becomes erratic and unstable at the end (Fz). Modified from Yazawa [10], Chapter 2.*

#### **Figure 3.**

*A long-term EKG from "Mokuzu" crab (Eriocheir japonica). Recording for 11 h. Inset: SI values for the corresponding period from (A) to (D). Note: No fibrillation remained after beating stops: cf.* **Figure 2***. Inset: spike configuration not distorted. Modified from Yazawa [10], Chapter 2.*

heart stopped its beating 11 h after TY left (**Figure 3**). We define this "unpredictable death." Unpredictable death is a rare event among ~1000 specimens. We always check and dissect all specimens' body after the death. In case of **Figure 3** animal, dissection revealed that the myocardium of relevant crab partially got slightly injured by an EKG electrode (see the electrode in **Figure 1B**). It is the fault of researchers. We are very sorry that the innocent specimen suffered from the human-caused heart injury for 2

**37**

observation.

*mDFA Detects Abnormality: From Heartbeat to Material Vibration*

weeks, although we did not know that. From this rare case, we learned that little injury of myocardium causes sudden death. Only partial damage of the heart is life-threatening. It is comparable to a human health problem, well known ischemic heart disease.

Results of **Figure 3** surprised us, the suffering crab's SI values "always" exceeded 1.0 (see **Figure 3**, SI = 1.5, 1.4, 1.4, 1.2). We have never seen before. A hypothesis came into my head: "injured heart has a very high SI." This hypothesis is unproven as far as we know. We have seen many dying specimens that showed reduction of

The results suggest that "the scaling exponent methods" distinguish damaged heart from unhurt heart. We biologists consider that medical profession should test mDFA on human hearts. We sent a short abstract to a medical congress in Europe, but the application was rejected immediately. We ourselves began to study human

In 1982, Kobayashi and Musha reported that healthy hearts exhibit 1/f spectrum [8]. Mathematically, 1/f slope is almost equal to SI = 1.0, while not 100% equivalent. This metric analysis based on SI is not fully proven as far as we know. The criterion-based strategy is better than qualitative research for

For the quantitative expression for the CS state, we need computation. However, in the 1980s, we did not have a PC to calculate SI. Poor biologists found difficulty to use a computer that was installed in a building of a top university. It took until 2001 to prove the idea of mDFA by ourselves. The Windows XP machine was introduced in the year 2001. XP-PC helped us calculate mDFA on the second

What we liked was Kobayashi-Musha's concept that one (SI = 1.0) is "healthy" [8]. There is a fixed baseline for diagnosing the heart system, that is,

In the 1990s, Peng and Goldberger and others demonstrated that healthy hearts exhibit the scaling exponent ONE (1.0) by detrended fluctuation analysis (DFA) [9] [DFA is not mDFA (see below)]. These results add critical evidence to the issue

Moreover, Peng and Goldberger's group reported that sick hearts exhibit a higher SI, which is SI = ~1.2. It sounds like providing evidence that a sick heart was consistently higher in the scaling exponent. But they only suggested. The truth was unclear. At least we were excited about our crab's high-SI discovery (**Figure 3**)

Most of the data in [8] and [9] were obtained from in-hospital patients. Peng and Goldberger's group did not extend their detailed experiments to general popu-

One is a baseline number for the health. This is testable hypothesis. We began to examine EKGs on general population and model animals. Currently we have ~500 individuals' EKG and ~1000 animal data. Some EKGs are collected from long-term follow up. Some subjects have passed away. We take medical record with all data including animal data. We never use website data. Physiological interpretation of data is impossible without medical record based on our own physiological

*DOI: http://dx.doi.org/10.5772/intechopen.85798*

We found it crab's "unpredictable death."

SI-value as shown in **Figure 2**.

hearts.

**5. Biophysics**

**5.1 Quantitative analysis**

diagnosing the CS.

time scale.

healthy or not.

of Kobayashi-Musha's concept.

because it coincides with it.

lation as far as we know.

*mDFA Detects Abnormality: From Heartbeat to Material Vibration DOI: http://dx.doi.org/10.5772/intechopen.85798*

weeks, although we did not know that. From this rare case, we learned that little injury of myocardium causes sudden death. Only partial damage of the heart is life-threatening. It is comparable to a human health problem, well known ischemic heart disease. We found it crab's "unpredictable death."

Results of **Figure 3** surprised us, the suffering crab's SI values "always" exceeded 1.0 (see **Figure 3**, SI = 1.5, 1.4, 1.4, 1.2). We have never seen before. A hypothesis came into my head: "injured heart has a very high SI." This hypothesis is unproven as far as we know. We have seen many dying specimens that showed reduction of SI-value as shown in **Figure 2**.

The results suggest that "the scaling exponent methods" distinguish damaged heart from unhurt heart. We biologists consider that medical profession should test mDFA on human hearts. We sent a short abstract to a medical congress in Europe, but the application was rejected immediately. We ourselves began to study human hearts.
