**4. In vitro methodology**

*Cardiac Diseases - Novel Aspects of Cardiac Risk, Cardiorenal Pathology and Cardiac Interventions*

thermo-fluid dynamics properties of biofluid/blood along with the vessel blockage in terms of the hydraulic diameter. Note that nanoscale fluid flow system with apparently high-risk blockage (**Figure 1(a)**) must always maintain the flow Mach number less than one as dictated by Eqs (2) and (3) for negating the undesirable internal flow choking causing shock wave generation and pressure-overshoot in the CVS leading to acute myocardial infarction. In such cases the flow Mach number can be retained always less than one by keeping BPR always less than the lower critical hemorrhage index (LCHI), which can be achieved by increasing the BHCR through drugs or otherwise. Analytical model (Eq. (2)) proves that the stents could reduce the risk of the heart attack but no better than drugs for increasing the BHCR owing to the fact that the Sanal flow choking could occur with and without stent. The impeccable analytical models presented herein as Eqs (2), (3) reveal that the usage of blood-thinners without increasing the BHCR create high risk of bleeding and stroke. The fact is that the blood-thinner decreases the viscosity and increases the *Reynolds number*, which augments the turbulence level causing an enhanced boundary layer blockage, which predisposes for an early flow choking. The flow turbulence enhances the deficit of energy in the type of friction, which increases the boundary layer blockage in the vessels and generates heat and augment the internal energy affecting a reduction in BHCR. Additionally, turbulence enhances the perfusion pressure essential to push the blood flow, which creates an early

In order to avoid internal flow choking in CVS an unchoked–fluid-flow condition must be maintained throughout the circulatory system. It could be achieved by maintaining the BPR always lower than the lower-critical-hemorrhage-index (LCHI), which is dictated by the lowest value of the BHCR (Eq. (4)) of the evolved gases from blood or foreign gases entered in the CVS. Air can enter in veins and arteries during surgical procedures. It has been reported that non meticulous brain surgeries result in an air embolism. Significant venous air embolism may develop acutely during the perioperative period due to a number of causes such as during head and neck surgery, spinal surgery, improper central venous and hemodialysis catheter handling, etc. The trend of using self-collapsible intravenous (IV) infusion bags instead of the conventional glass or plastic bottles has several advantages, one

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( ) ( ) /( ) <sup>1</sup> 1

2

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Note that BHCR of CO2 is lower than air, which creates an early internal flow choking. For instance, if CO2 is the dominant gas in the CVS it is mandatory to maintain BPR lower than 1.82, within the pathophysiological range of human temperature, for creating an unchoked flow condition for prohibiting the shock wave generation [1] causing asymptomatic cardiovascular diseases due to transient pressure-overshoot. Note that BHCR of CO2 decreases from 1.31 @ 0 °C to 1.281 @ 100 °C. Eq. (4) shows

æ ö +

*evolved gases with the lowest BHCR BHCR*

< = ç ÷

2

*blood BHCR*

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*blood blood BHCR BHCR*

*lowest lowest BHCR BHCR*



(4)

(5)

undesirable Sanal flow choking in the circulatory system.

of them being protection against air embolism [31].

*UCHI*

*BPR LCHI*

**3.1 Lower critical hemorrhage index**

**328**

In vitro data [6] shows that nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) gases are predominant in fresh blood samples of the human being/*Guineapig* at a temperature range of 37–40 °C (98.6–104 °F), which increases the risk of internal flow choking leading to the asymptomatic cardiovascular risk. It is evident from the reported results (**Figure 4**), exceeding the thermal tolerance level, that the possibilities of internal flow choking in the human being is higher than the animal (*Guinea pig*) under the same thermal loading condition as the BHCR of the dominant gas evolved in the animal is found consistently higher than the human being. As a result, the LCHI is higher for the healthy male *Guinea pig* as dictated by the Eq. (4). The mass spectrum of N2 is reported higher in animal whereas in human being CO2 is found higher [1, 6]. The BHCR of N2 is 1.4 and that of CO2 is 1.289 at a temperature of 300 K (80.33 F). At this thermal loading condition, an early internal flow choking occurs in the human artery at a BPR of 1.82 compared to an animal (*Guinea pig*) artery at a BPR of 1.89. It proves that the thermal tolerance level of the healthy *Guinea pig* is higher and the cardiovascular risk is lower than the human being under identical conditions. Therefore, increasing the thermal tolerance level in terms of BHCR of the human being is an important factor for reducing the risk of asymptomatic cardiovascular diseases caused by the shock waves as a result of internal flow choking. **Figure 5** is demonstrating the percentage variations of evolved gases (viz., N2 -m/z = 28, O2 -m/z = 32, CO2 -m/z = 44, Ar -m/z = 40, an unknown composite gas -m/z = 28.5), from blood samples of four different healthy human beings and one healthy male *Guinea pig* of four weeks old, during the hyphenated technique at a blood temperature of 40 °C (104<sup>o</sup> F). The estimated UCHI of healthy human being of age 23–56 with different blood group is presented in **Table 1**.

**Figure 4.**

*The mass spectrum of CO2 and N2 evolved as a function of both time and temperature in the blood samples of healthy subjects [1].*

#### **Figure 5.**

*Demonstrating the percentage variations of evolved gases (viz., N2-m/z = 28, O2 m/z = 32, CO2-m/z = 44, Ar-m/z = 40, an unknown composite gas - m/z = 28.5) from the blood samples of four different healthy human beings and one Guinea pig during the hyphenated technique at a blood temperature of 40 °C (104o F) [2].*


**Table 1.**

*Prediction of the UCHI from the heat capacity ratio of fresh blood samples of healthy human being of age 23–56 [2].*
