HCM Flashcards
A 63-year-old woman collapses in her local shopping centre then goes into ventricular fibrillation. A portable defibrillator is used to restore normal heart rhythm by allowing the “pacemaker” of the heart to reset itself. Which channels underlie this intrinsic rhythm?
Delayed rectifier K+ channels High -voltage activated Ca2+ Hyperpolarisation-activated cyclic nucleotide-gated (HCN) channels Low voltage activated Ca2+ channels Voltage=gated Na+ channels
Hyperpolarisation-activated cyclic nucleotide-gated (HCN) channels
You are revising your learning on muscle contraction. Muscle contraction in both skeletal and non-pacemaker regions of the heart depend upon electrical excitatation of myocytes by an action potential. You note that the shape of the action potentials in these two tissues differ in their shape and duration. These differences can be explained by which ionic current?
Inward long-lasting calcium current Inward transient calcium current Inward fast sodium current Inward slow sodium current Outward potassium current
Inward long-lasting calcium current
A potential new diagnostic test for urinary tract infection is found to give positive results in 120 out of 200 patients tested and in 40 out of 120 control individuals. What is the diagnostic sensitivity of this test?
33% 50% 60% 67% 75%
60%
Sensitivity = (True positive(A)/Total Disease) x100
= (120/200) = 60%
A potential new diagnostic test for urinary tract infection is found to give positive results in 120 out of 200 patients tested and in 40 out of 120 control individuals. What is the positive predictive value of this test?
33% 50% 60% 67% 75%
75%
PPV=True positive (A)/Total positives
=(120/(120+40)) x 100
ECG trace
ask Dad
You are recording ECG trace is in clinical trial participants. You are particularly interested in measuring the ST segment each person. What period of time does this represent?
Time between ventricular depolarisation and ventricular repolarisation
Time between atrial depolarisation and ventricular depolarisation
Time between atrial depolarisation and atrial repolarisation
Heart rate of the participant.
Duration of conduction through the atrioventricular node.
Time between ventricular depolarisation and ventricular repolarisation
ST segment =ventricular depolarisation and ventricular repolarisation
Hypertrophic cardiomyopathy is an autosomal dominant inherited condition which leads to left ventricular hypertrophy LVH and risk of sudden cardiac death. The function of which component of the cardiomyocytes is the mainly affected in this condition?
Adherens junctions Desmosomes Sarcomeres Sarcoplasmic reticulum T tubules
Sarcomeres
HCM is predominantly caused by mutations in the genes encoding proteins of the sarcomere e.g. cardiac myosin binding protein C or the beta myosin heavy chain.
You are working as a research assistant and you want to determine whether myeloperoxidase is upregulated in Kupffer cells using sections of liver taken from the mice following induction of experimental hepatitis. Which lab tech will be the most appropriate to use?
ELISA Flow cytometry Immunohistochemistry PCR Western blotting
Immunohistochemistry
Arrthymogenic right ventricular cardiomyopathy is an autosomal dominant inherited condition which leads to dilation, fatty infiltration and fibrosis of the right ventricle..
Adherens junctions Desmosomes Sarcomeres Sarcoplasmic reticulum T tubules
Desmosomes
Cardiomyocytes acts as a functional syncytium (compare to multinucleate and are a syncytium). Which component of the cardiomyocyte intercalated disc facilitates this?
Adherents junction Desmosome Gap junctions Sarcomere Tight junctions
Gap junctions
Many human diseases are caused by non-synonymous genetic mutations that alter the amino acid sequence of the transcribed proteins. Which type of mutation would be most likely to result in a frame shift?
Chromosomal translocation
Deletion of three base pairs
Insertion of one base pair
Substitution of one base pair
Trinucleotide repeat expansion
Insertion of one base pair
A 27-year-old neighbour tells you that his father suffers from mild HCM and his paternal grandfather died from the condition. Regular testing has shown his heart to be healthy but he got married and the couple are trying for a baby and he’s worried his children may be affected. Why is it possible that his offspring HCM despite his healthy heart.
HCM is recessive condition. HCM is caused by an acquired mutation. HCM is not an inherited condition. HCM often skips a generation. HCM shows incomplete penetrance.
HCM shows incomplete penetrance.
Explanation: penetrance is the percentage of individuals that exhibit the phenotype. HCM does not show 100% penetrance and the penetrance his age-dependent. The 27-year-old potential father may still exhibit disease symptoms later in life.
A pregnant woman in the third trimester of her pregnancy visits her GP. She is concerned that a child may suffer from HCM,a condition from which the father of the child recently died. He carried a common sarcomeric mutation mutation and she wants to know what the probability is
that her child will suffer form HCM. What is the probability that her child will have the same mutation as his father?25%
50%
75%
100%
0%
50%
HCM is autosomal dominant and mongenic. The father will be heterozygous. Homozygous individuals do not usually live (embryonic lethal). The child that he will pass his affected (mutant) allele is 50%.
