Upon arrival at the
Medizinische Hotschule, Jessica, Carlos, and myself made our way toward ward fifteen
where we were supposed to meet Dr. Hanke and Dr. Schmitto who were our mentors
for the day. I asked a receptionist where
we could find either doctor, and she said Dr. Schmitto should be arriving
within the next fifteen minutes. We must have stood out like a sore thumb,
because just a couple minutes later Dr. Schmitto was able to identify us from
the other end of the wing before we even saw him. After a very brief introduction, Schmitto
escorted us to his office where he told us to store our belongings. He then doled out three white lab coats
bearing his title, Pd Dr. Schmitto, on
the lapel. We briskly donned the garbs
and left the room at Schmitto’s lead. In
the hallway, we were introduced to Dr. Hanke.
Introductions were once again quick as we appeared to in a hurry. The rationale behind the rushing around
became apparent as we were led into a lecture room filled with doctors bearing
the same white coats we were, except theirs bore their own respective titles. There
could only be four Dr. Schmitto’s of course.
At the front of the room, there were two projector screens cycling
through CT and MRI images at the command of a doctor who appeared to be in
charge. As the images would cycle
through, the doctor in charge would say the patients name and another doctor in
the audience would start rattling away in a seemingly intelligent fashion in
German. It was later explained to us
each doctor was stating their case and then the other doctors would consult as
to various potential options. After the
consultation was over, Dr. Hanke took us under her wing and led us back to ward
fifteen. She then took out a piece of
scratch paper and gave us a brief review of the functions of the heart and how
VADS functioned and why they were a solution.
Left
heart failure can be caused by many problems. The most common being myocardial infarction
and dilated cardiomyopathy. A myocardial
infarction, or heart attack, occurs when there is a blockage in a coronary
artery and the resulting ischemia causes death in the myocardiocytes who are no
longer being supplied with oxygen. Once
these cells die, they are replaced with scar tissue which lacks the functions
of myocardiocytes and, as a result, the contractility of the heart is generally
decreased depending on how severe the infarction was. In dilated cardiomyopathy, a non-ischemic cardiomyopathy,
the heart grows, vessels thicken and its pumping functionality is altered. Dilated cardiomyopathy is related to
hypertrophy, or growth, that is either eccentric or concentric. Concentric hypertrophy
is common in athletes whose hearts grow as a result of chronic demand for oxygenation
of active muscle groups. Eccentric
hypertrophy can be caused by genetic mutation, or by toxic, metabolic, and
infectious agents which can all cause the heart to disproportionately grow in
size. Both the death of myocardiocytes
and dilated cardiomyopathies lead to a decompensated heart, a heart that is heterogeneous
in its ability to contract and pump blood.
In patients with left or right heart failure, the patient’s respective
ventricle can no longer pump enough blood to sufficiently oxygenate the tissues
of the body. The VAD, or ventricular
assist device, assumes the job of a ventricle by pulling blood from the ventricle
and pushing it directly to the aorta or pulmonary artery by means of a rotor
and an outflow line. In the particular
model of LVAD, left ventricular assist device, and its procedure Dr. Hanke
explained, a ring is sutured to the left ventricle and then that ring serves as
an attachment site for a block-shaped rotor mechanism whose job is to push
blood. An artificial tubing is then attached
to the LVAD at one end and sutured to the aorta at the other. Finally, a hole must be made in the patient
for a wire, called the drive line, which connects the control system located outside
the body to the VAD inside the body. The
drive line hole is made either on the left or right side of the patient’s lower
abdomen. The patient may select the side
of incision and typically chooses the same side as their dominant hand. The power sources, which are connected to the
control mechanism, consist of two batteries, which can function for six hours
before needing to be recharged. The control
system only uses one battery at a time, so while one battery is being used, the
other can be charged. This serves to
protect the patient in the rare case one of the batteries fail. At night, or whenever the patient chooses, he
or she is able to utilize wall outlets instead of the batteries, to avoid being
alerted by a loud alarm which will sound if the batteries are running too
low. Patients can also use a car converter
to power the device with a cigarette lighter if the patient is going for a long
car ride. The batteries along with the
control system, weigh a grand total 2.2 kilograms.
In patients with right heart failure the same process is used however an
RVAD will be sutured to the right ventricle.
Some patients who have both left and right heart failure will be
eligible for a bivad. A bivad
implantation involves the insertion of both an LVAD and an RVAD. A bivad implantation is preferable to a total
heart transplantation as the procedure is less dangerous for the patient. Patients with a bivad will have two
drivelines instead of one, and a control apparatus for each driveline.
The VAD can serve in three major ways, as a bridge to
recovery, as a bridge to transplant, or as a terminal solution. In the case of the VAD being a bridge to
recovery, in small number of cases, the heart is able to repair itself to a
point where it is once again capable of oxygenating the tissues of the
body. Once a physician has evaluated the
condition of the heart and deemed it acceptable, the VAD will be removed. For many patients the VAD is a temporary
solution as they wait for a donor heart.
Once the patient is at the top of the donor list, and a heart has been selected
for transplantation, the heart, along with the VAD, will be removed and the new
heart will be transplanted. Sometimes a VAD
patient is determined to be too weak to survive a heart transplant. In these cases the VADs will be left in their
bodies for the remainder of their lifetime.
No comments:
Post a Comment