“God contracts and expands.” (2:245)

The heart is a fairly small muscle that beats 100,000 times a day and produces roughly 115,000 Joules of energy, enough to boil a cup of water for some tea. Like a flowing river, deoxygenated blood travels from the right side of our body to the right side of our heart via valves and chambers until passing through our lungs, where each breath we take facilitates the oxygenation of every individual blood cell with 4 molecules of oxygen. The now oxygenated blood, continues to progress, never stopping, now through the left side of the heart, again passing through valves and chambers, eventually being pushed out to the rest of our body with the help of the left ventricle. The left ventricle is the thickest, largest, strongest, and most muscular part of the heart because it has the responsibility of pumping oxygenated blood through the aortic valve and aorta to the rest of our body. If this continual circulation is ever interrupted, it can lead to catastrophic outcomes.

There are several ways this flow can be interrupted, many of which happen before birth and require immediate surgery after delivery. Congenital heart defects (CHD) are some of the most common types of birth defects, but as medical care and treatment have advanced many of the babies that suffer from them usually end up living long and healthy lives. Treatment isn’t required while babies are in their mother’s womb, because the circulation of the heart is different before the baby takes its first breaths, and there is normally a mixing of oxygenated and deoxygenated blood. CHD can be mild, like a hole in the heart between two chambers that allows the mixing of oxygenated and deoxygenated blood. Ventricular septal defects and atrial septal defects (holes in the heart) are some of the most common forms of CHD. Sometimes these defects can be resolved on their own or may not be realized until much later in life, or they may require a “patch” repair if they are larger. VSDs and ASDs are associated with Down’s Syndrome, and maternal risk factors including diabetes, obesity, and smoking. Patent foramen ovale (a hole in the heart that fails to close) is found in up to 30% of the general population. It usually requires no treatment and isn’t discovered unless complications like a stroke occur later in life by having a blood clot form, requiring the blood to then travel through the hole, and then be shot up through the aorta into the brain. All babies are born with patent (open) ductus arteriosus – the ductus arteriosus is a fetal blood vessel that allows flow from the right heart to the aorta, necessary when the baby is in their mother’s womb, but incompatible for life after the baby is born. Within the first few days of life, this blood vessel should close and eventually transform into a ligament that helps tether the pulmonary artery and aorta to each other. If closure fails and the ductus arteriosus remains patent, a continuous machine-like murmur can be heard with a stethoscope, and treatment with indomethacin is started. Untreated, a PDA would result in cyanosis (blue/gray skin) and Eisenmenger Syndrome due to decreased oxygen delivery [1].

The heart’s responsibility is not only to provide oxygenated blood to the rest of the body but to also somehow feed itself. The heart’s muscles exhaust 11.6% of the body’s total oxygen consumption in order to maintain its own contractile activity, coming in 3rd after the liver (20.4%) and the brain (18.4%). During contraction or systole, the heart pumps at 120 mm Hg to provide blood through the aorta and arteries. During relaxation, or diastole, the heart expands and allows for blood to fill into its chambers and also flow through the coronary arteries. These coronary arteries are the arteries that will feed the heart itself. Thus, in order to feed itself the heart must relax and therefore allow its coronary arteries to expand and provide blood to itself. When the heart is contracting and providing blood to the rest of the organs it is too constricted to provide blood to itself. Since these branches are located within grooves of the heart, when the heart is systole the arteries are too constricted for blood flow due to increased tension. This is especially true regarding the arteries supplying the left ventricle since it is larger and more muscular – remember this is where the aorta will branch off, providing oxygenated blood to the rest of our body.

This balance between contraction and expansion may remind some readers of the concepts of Qabd (contraction) and Bast (expansion) in Sufism or Tzimtzum in Jewish mysticism, and how one truly feeds the other thus allowing for growth through this cycle of contraction and relaxation. Tzimtzum is used to explain the process of creation, a contraction of infinity happening to give birth to a finite universe [2]. The Sufi tradition is a personal journey described as “contraction and openness are mysterious ‘bargains’ that have been made without the will or intention of the traveler. The first one blocks his or her way; the second one gives him or her wings to fly to new heights [3].” What is perhaps most interesting is that our physical heart performs this contraction and expansion perfectly so long as we take care of it, whereas our spiritual heart can have lapses in this critical exercise. Maybe, if we understand how to take care of our physical heart, we will also find the answer to keeping our spiritual heart healthy. Prophet Muhammad, peace be upon him, emphasizes this connection as follows: “Verily, in the body is a piece of flesh which, if sound, the entire body is sound, and if corrupt, the entire body is corrupt. Truly, it is the heart.”

Some ways to take care of our physical hearts include incorporating more physical activity into our daily lives, eating less and healthy, and controlling our stress. Perhaps our spiritual health would also benefit from these and similar activities, including regular acts of worship, fasting, controlling our temper, and being kind to others. When we don’t take care of our physical heart, it begins to fail since oxygen ceases to be delivered to our heart and the electrical currents can no longer travel effectively, thus resulting in a heart attack.

Coronary artery disease is the leading cause of death worldwide, and especially in developed countries. The deadliest heart attack occurs if there is a blockage of the left anterior descending coronary artery, which is why it is tragically termed the “widow maker.” Beginning from adolescence, arteries begin to accumulate fatty streaks and progress to an atherosclerotic plaque. This plaque can lead to several disastrous complications such as follows:

• a narrowing or complete obstruction of an artery, impairing blood flow and leaving the heart thirsty for oxygen
• a stroke due to a blood clot caused by decreased movement, breaking off and flowing to the brain
• a weakening of the vessel wall leading to an aneurysm, the vessel bursting

For some patients, a heart attack becomes a wakeup call in order to make the many necessary lifestyle changes that are necessary in order to live a long and healthy life. However, 20% of patients will experience a second heart attack. As the heart gets weaker and weaker it can eventually develop cardiorenal syndrome, a complication that results from the heart being unable to pump effectively resulting in it getting backed up in the heart and the right side of the body. This increase in volume in the body is further exacerbated by the kidneys, which continue to retain fluids and thus cause the body to become overloaded. This leads to edema, or swelling, in the legs that can eventually progress to the lungs and cause congestive heart failure. As the kidneys try to ameliorate the fact that the heart is not pumping effectively, they ultimately worsen the situation leading to end-stage renal disease and stage D heart failure.

Of course, as with almost all medical conditions, these fatal results can be prevented much earlier with lifestyle changes, even before introducing medical intervention with prescription drugs or other procedures. These lifestyle modifications include moderate aerobic exercise at least 3 times a week, a diet rich in vegetables and low in fats, sugars, and carbohydrates, smoking and alcohol cessation, and weight reduction (which would come as a result of these modifications). It is also important for patients that are already dealing with hypertension, diabetes, and hyperlipidemia should keep them well-managed and controlled.

Maybe similarly, some simple lifestyle changes, such as putting aside a few minutes every day to reflect, can be the secret to keeping our spiritual heart healthy. Our heart must remain healthy to keep the rest of our body healthy. Considering the close relationship between our physical and spiritual heart, our spiritual heart must be kept healthy to keep the rest of our spiritual body healthy. Spiritually healthy individuals will further reinforce the health of our community, for Prophet Muhammad, peace be upon him, says, “The believers in their mutual kindness, compassion and sympathy are just like one body. When one of the limbs suffers, the whole body responds to it with wakefulness and fever.”

“As the whole of existence is in His grasp and at His free disposal, it is He Who directs and disposes of all things, from the heavens to the human heart… When God wills, He contracts a heart so tightly for what only He can provide that only He can satisfy it. By contrast, He expands and exhilarates it to such an extent that it needs nothing. Contraction is caused by God’s Majesty; openness is caused by His Grace. (Fethullah Gülen, Emerald Hills of the Heart).”

References

• https://www.heart.org/en/health-topics/congenital-heart-defects
• https://www.britannica.com/biography/Isaac-ben-Solomon-Luria#ref163236
• http://fgulen.com/en/fethullah-gulens-works/key-concepts-in-the-practice-of-sufism-1/qabd-and-bast-contraction-and-openness

By examining the heart of a crocodile, researchers have discovered how it is that an air-breathing land animal can manage to glide through murky waters for several hours without the need to surface.

There is that one scene in documentaries that we often come across on television: Crocodiles gliding gracefully inside the water, waiting for hours for the perfect time to pounce and snatch their prey from their necks and into the water. But how do these animals manage to stay underwater for almost two hours without surfacing for air even though they, just like human beings and other land animals, live on pulmonary respiration and are in need of the free oxygen in the air?

A member of the reptiles class, crocodiles do not have gill nor can they have skin respiration since their skin is covered with a thick and airtight keratin armor. Just as every living organism are provided with a suitable anatomic and physiological character for their survival, crocodiles are also granted with a system that facilitates their long stay in the water.

Crocodiles are bestowed with a special heart anatomy different to other reptiles like lizards, tortoises, and snakes. The hearts of other reptiles are designed to contain three sections including two atriums and one ventricle. The right atrium, which collects the returned oxygen-deprived (deoxygenated) blood and the left atrium which collects the oxygen-rich (oxygenated) blood retrieved from pulmonary arteries of the lung, transports the blood to one common ventricle. Because there is only one ventricle to receive and combine oxygenated and deoxygenated blood, a mixture of less oxygenated blood is pumped to their body. Depending on outside temperature, the body temperature of a reptile increases or decreases. Their metabolism slows down, almost to a halt, while their body temperature decreases when outside temperature drops near or beyond freezing conditions. Hibernation begins as a result. Frogs and reptiles stop hibernating as soon as their body temperature increases depending on the outside temperature when the weather gets warm. These organisms are called cold blooded animals (with variable body temperatures) because of this feature.

The heart of a crocodile is different to other reptiles in that it has four chambers just like birds and mammals. Blood is sent to the lungs for gas exchange from the right, and from the left ventricle it is pumped to the body. Thus the two types of blood do not mix in the heart. However, what is interesting is that blood is mixed as soon as it leaves the heart via a valve (foramen of panizza) placed in between the right and left aorta.

What could be the purpose of blood, which does not normally mix in the heart, mixing through the medium of a hole? Does this opening in between two aortas indicate a flaw? It is understood after some research that this hole in fact is not a flaw or an anomaly; on the contrary, it is a necessity for a metabolism suited perfectly to the lifestyle of the crocodile.

Warm blooded vertebrates like birds and mammals with a four chamber heart have faster metabolic speeds and higher blood pressures. For these organisms can only supply the energy they consume during their daily activities via such a fast metabolism and a high level of oxygen provided with oxygenated blood.

If the metabolism of a crocodile was fast like mammals all throughout the year, it would have to continuously be nourished and use oxygen. Furthermore, because crocodiles do not have much predators, they could have also lead to the extinctions of some species by overpopulating if they featured a faster metabolism. The low ratio of heart-body mass in crocodiles (0.15%) compared to mammals and birds (0.40%-0.50%) cause the movements of crocodiles to be relatively slower. The Almighty, who creates everything with his wisdom, lowers the blood oxygen ratio and the metabolic speed of crocodiles by creating a valve that combines the two aortas. Thus eliminating the possibility of crocodile overpopulation.

Crocodiles have two aortic arches whereas mammals only have a left, and birds have one right aortic arch. The left aortic arch, despite some contact with the returned blood via foramen of panizza, delivers the oxygenated blood towards intestines, stomach, spleen and the liver after receiving it from the left ventricle of the heart. This is because the digestive system of a crocodile requires oxygen-rich blood. Deoxygenated blood while exiting the right ventricle goes towards the pulmonary arteries of the lung for exchange and mixes with oxygenated blood coming from the right aorta, feeding other organs that are instrumental for its slow metabolism.

Under the water, separated oxygen-rich and oxygen-poor blood mixes when exiting the heart and switches route, thus making oxygenated blood vessels start to carry oxygen poor blood. So what is the reason behind this switch in the direction of the bloodstream under the water? See at this point, the extraordinary features of the crocodile blood circulation system kick in. The two anatomical features belonging only to only crocodile hearts is what enables them to stay under water without breathing. Because of little or no lung use under the water, a big portion of the blood stream is diverted away from lungs; therefore oxygen poor blood is pumped back to the body. As one feature of the two, foramen of panizza restricts (does not close) upon signals coming from nostril sensors under the water but expands and remains open on land. The two aortic arches connects with each other via foramen of panizza as soon as they leave the heart but merge completely in the lower parts of the body away from the heart (anastomosis).

The second feature stems from a serrated valve. Refilling of pumped blood is stopped via a passive, thin leaf-shaped valve which is located at the tip of the pulmonary artery exiting the right ventricle. Thus, one-way direction of blood flow in the heart is maintained. These valves, which carry nodules made of connective tissue, constrict during the dive and blood flow to the lungs is reduced greatly. Therefore blood rejoins the systemic circulation from the right aortic arch.

The blood circulation of crocodiles is similar to birds, mammals, and humans while they are active on land. Oxygen-deprived blood is sent to lungs for gas exchange. The only difference is the turning of the right aorta to the left and the left aorta to the right. Oxygen rich blood not only flows through the left aorta but also through the right aorta via foramen of the panizza as well causing distribution via two channels into the body. However, the foramen of the panizza being open is not sufficient for these two channels to be used. At the same time, the pressure of the blood within the left ventricle needs to be higher as well. This way, high pressure oxygenated blood flows into the right aorta through the opening of the panizza, applying pressure to the valve at the tip of the right aorta to close it in order to prevent the mixing of the oxygen-poor blood into this route. As a result, oxygenated blood gets distributed quickly by each aortic arch without mixing with the used blood. Thus, oxygen-poor and oxygen-rich blood follows the following route on land

* Deoxygenated blood: Body – superior and inferior pulmonary veins – right atrium – right ventricle – lung pulmonary artery – lungs.

* Oxygenated blood: Lung pulmonary vein – left atrium – left ventricle – right aorta and left aorta via panizza valve (both aortas are active) and body.

The opening of the panizza narrows with the help of signals coming from the nostrils when crocodiles submerge. At the same time serrated valves at the tip of pulmonary artery that transports the blood to the lungs also constrict. While this serrated valve is at work, a majority of the blood returning from the body is not sent to the lungs because they are not functioning at the time. This serrated valve also increases the pressure of the right ventricle. This pressure, along with elevated resistance in pulmonary circulation and lowered pressure of systemic circulation, leads to the opening of normal valves at the tip of the left aorta. In the end, the left aorta which normally carries oxygenated blood on land starts carrying oxygen deprived blood, and there is a route switch.

The most beneficial part of this switch is to re-route the deprived blood back to the body via a different route, that is, the left aorta. This by-passes the lungs and prevents time loss. Despite the fact that blood of the left aorta mixes with the oxygenated blood of the right aorta to some degree via the panizza valve, the main function of this opening while submerged is to supply blood flow to the arteries feeding the heart and brain through the transfer of some poor blood from the left aorta into the right aorta; this way vital organs are not left without blood.

Blood returning from the body is not sent to the lungs for gas exchange when crocodiles are under the water. However, existing oxygen in the blood can be delivered to the tissues quickly by a route switch. The amount of bicarbonate ions that is important in the transport of CO2 in the blood increases when oxygen pressure in the tissues drop. Anaerobic respiration of tissues increases. This leads to an increase in lactic acid levels and reduces pH. Eventually, it facilitates the release of oxygen carried by hemoglobin. In the end, oxygen that is bonded with hemoglobin is used more efficiently. In the meantime, the body temperature of a crocodile submerged under water decreases and slows down its metabolism, reducing the need for oxygen. Oxygen stored in the blood can be sufficient up to two hours under the water. However when these reserves are consumed, crocodiles have to resurface to breathe even though it may cost a prey to escape.

Crocodiles can live on land and in the water and adapt to their environments with ease and efficiency thanks to the ponderous working of their mechanisms under water, the change in blood circulation, slow blood flow, reduced body temperature and metabolic speed bestowed upon them. Just like humans in sleep, crocodiles can remain submerged for long periods (4-6 minutes in usual dives; up to 2 hours when pressed) with this perfect system granted to them. Crocodiles use these mechanisms not only when under water, but also while resting or for periods after heavy feeding.