The cardiologist may use venogram to diagnose
VARICOSE VEINS, VENOUS INSUFFICIENCY, or DEEP VEIN
THROMBOSIS (DVT). For venogram, the radiologist
injects a small amount of contrast dye into the
affected VEINnetwork and then takes X-rays or
fluoroscopy images as the dye moves with the
blood through the veins. The venogram shows
any structural abnormalities and occlusions.
Venogram requires no preparation or recovery.
Some people experience a minor burning sensa-
tion with injection of the contrast dye. People
who are allergic to iodine may have an allergic
reaction to the dye.
See also ULTRASOUND; X-RAY.
ventricular assist devices (VADs) Implanted
mechanical pumps that aid the native HEART, tak-
ing over some of the workload of the ventricles.
Several types of VADs are available, each with
somewhat different features and functions. A VAD
may assist the right or left ventricle, and in some
cases both ventricles, as a bridge device while
awaiting a donor heart for HEART TRANSPLANTATION
or as a permanent device to treat end-stage HEART
FAILURE, a therapeutic application sometimes called
destination therapy. The VAD sometimes allows
the heart to recover sufficiently that the VAD
becomes unnecessary and the surgeon can remove
it. The OPEN HEART SURGERYto implant the VAD
takes between three and eight hours, depending
on the person’s cardiovascular status and the type
of VAD the surgeon is implanting.
Though VADs offer hope of extended survival
and improved QUALITY OF LIFEfor many people
whose heart failure would otherwise be fatal, liv-
ing with an implanted device requires conscien-
tious and consistent attentiveness. Recipients must
take anticoagulant medications and may require
other medications, depending on their underlying
CARDIOVASCULAR DISEASE (CVD). Ongoing risks
include INFECTION, mechanical failure of the VAD,
damage to blood cells, bleeding at the implant site,
clot formation resulting in STROKEor PULMONARY
EMBOLISM, and worsening of cardiovascular status
that may require additional therapeutic interven-
tion including surgery. Because the VAD became
an approved treatment in the United States only
in 2004, doctors do not yet know the long-term
benefits and risks of VAD implantation.
See also LIVING WITH CARDIOVASCULAR DISEASE;
MEDICATIONS TO TREAT CARDIOVASCULAR DISEASE;
ORGAN TRANSPLANTATION.ventricular fibrillation Rapid, irregular, ineffec-
tive contractions of the heart’s ventricles. Ventric-
ular fibrillation quickly becomes fatal without
treatment. The HEARTcannot pump blood to the
LUNGSor to the body when it is in ventricular fib-
rillation.Ventricular fibrillation is a life-threat-
ening event that requires emergency
medical treatment.The ELECTROCARDIOGRAM(ECG) provides a defini-
tive diagnosis. Treatment may consist of DEFIBRIL-
LATION(an electrical shock to the heart) or of
medications to restore normal rhythm. Ventricular
fibrillation typically follows a cardiac crisis such as
HEART ATTACK, and despite its lethal potential pres-
ents an opportunity for successful resuscitation
because the heart still has electrical activity. Ven-
tricular fibrillation may also exist as the deteriora-
tion of an ARRHYTHMIAdisorder such as ventricular
tachycardia (rapid, regular contractions of the
ventricles) or WOLFF-PARKINSON-WHITE SYNDROME.
See also ATRIAL FIBRILLATION; CARDIOPULMONARY
RESUSCITATION (CPR); PREMATURE VENTRICULAR CON-
TRACTION(PVC).Wolff-Parkinson-White syndrome An inherited
ARRHYTHMIAdisorder in which an extra conduction
pathway, called an accessory pathway, exists
between the heart’s atria and ventricles. The
accessory pathway allows the heart’s electrical
pacing impulse to bypass the normal conductive
route, reaching the ventricles before the atria have
completed their contraction cycle. While many
people who have Wolff-Parkinson-White syn-
drome never experience any symptoms, some
people have episodes of ventricular tachycardia, in
which the ventricles contract regularly though
very rapidly. Ventricular tachycardia is not very
effective in moving BLOODto the LUNGSand espe-
cially through body, resulting in feelings of light-
headedness or episodes of SYNCOPE(brief loss of
CONSCIOUSNESS) as the blood supply to the BRAIN
becomes diminished.116 The Cardiovascular System