Coronary ArteriesThe Basics and Beyond

Function of coronary arteries: delivery of oxygenated blood to the heart muscle (myocardium)

The VERY Basics

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Left coronary artery: arises from the left coronary sinus/cusp of the Aortic valve◦ Left main artery branches into:

LAD- Left Anterior Descending CX- Circumflex

Right coronary artery: arises from the right coronary sinus/cusp of the Aortic valve

Main Branches

Coronary arteries lie on top of the myocardium (epicardial) and follow the Atrioventricular (AV) groove and the Interventricular (IV) groove

CX courses along AV groove

LAD and distal RCA follow IV groove

Basics, cont

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LAD: diagonals and septals

CX: obtuse marginals, occasionally Posterior descending artery (PDA)

RCA: acute marginals, Posterior lateral artery (PLA), and PDA

Ramus intermedius: arises between LAD and CX in 5%-10% of population

Major Branches

A person can be “right dominant”, “left dominant”, or “co-dominant”.

This depends on which artery (or arteries) give rise to the PDA and PLA, which run along the posterior side of the heart.

Coronary Dominance

Right Dominant

The PDA branch arises from the RCA (60%-70% of population)

Left Dominant

The PDA arises from the LCA (10%-15% of population)

RCA gives rise to the PDA and then ends, while the CX supplies the PLA branches

CX may also supply a left PDA that runs parallel to the right PDA

Co-Dominant

As with all structures in the human body, WEIRD stuff can happen! A few examples:

CX originates with RCA from right sinus LM from right sinus RCA from left sinus Separate originations (ostia) for all three All three arteries from one ostia

Variations and Anomalies

Coronary aneurysms

Fistulas- abnormal communication with venous system

Anomalous origin of LCA from Pulmonary Artery (defect that can have a mortality rate of 90% in first year of life, due to MI or MR leading to CHF)

Anomalies

Adventitia- outermost, connective tissue covering the vessel

Media- smooth muscle cells◦ Spasm- contraction of cells causing disturbance of

blood flow (caused by numerous factors: caffeine or stimulant induced, catheter induced)

Intima- innermost, single layer of cells

Anatomy of an Artery

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LAD supplies: most of septum, anterior/lateral/apical LV, anterolateral pap muscle

CX supplies: LA, posterior/lateral LV, anterolateral pap muscle, SA node (45%), AV node (10%), septum, His bundle, posterior pap muscle, inferoposterior LV

RCA supplies: SA node (55%), RA, AV node (90%), septum, His bundle, posterior pap muscle, inferoposterior LV

Myocardial Blood Supply

Myocardial Blood Supply

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Coronary Arteries perfuse in diastole (this is part of the theory behind the IABP)

Coronary sinus collects used blood from the mycardium to send to lungs for re-oxygenation

Coronary bridging = compression of a coronary artery by the myocardium during systole◦ Usually benign, but can occasionally result in MI or

even death (most common with LAD)

Hemodynamics

Several medications are injected to elicit vasodilation in the arteries during catheterization, such as diltiazem, verapamil, adenosine, nitroglycerine, and nipride

IIbIIIa Inhibitors (abciximab, eptifibitide) are also directly injected in coronary arteries with apparent thrombus

Pharmacology

CAD and Atherosclerosis: What does this mean, exactly?

Build-up of fatty substances, cholesterol, cellular waste products, and calcium within the intima of an artery

With or without symptoms

Coronary Artery Disease

Pathophysiology of CAD

Rupture of fibrous cap

Platelets rush in to fix the vessel

Clot forms

Blood flow obstructed

Damage/death of myocardium

Pathophysiology of Acute MI

Many tests and screening tools are available to help detect CAD

Can be invasive or non-invasive

Can be performed in MD’s office or hospital, depending on type of test

Diagnostic Testing Methods

Treadmill- assesses coronary blood flow by ECG, blood pressure, and signs/symptoms during exercise

Stress Tests

Stress Echocardiogram-compares LV wall motion at rest and under stress◦ Used for low-moderate risk patients and younger patients

where there may be structural/valvular/congenital causes of symptoms

Stress Tests

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Perfusion scan- compares blood flow at rest and under stress by imaging the myocardium after a radioactive tracer is injected

Stress Tests

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Echocardiogram- assesses structural, valvular, and congenital causes of heart disease

Diagnostic Testing

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Cardiac MRI- useful for diagnosis of structural disease (cardiomyopathy, masses) with or without contrast◦ Gold standard for congenital heart disease

Diagnostic Testing

Cardiac Computed Tomography (CT)- evaluates coronary arteries as well as LV function, anatomy, and calcification (calcium score)

Diagnostic Testing

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Cardiac CT Images

64ctscan.comCsmc.edu

Coronary Angiography- used for positive and indeterminate stress tests, assessment of bypass grafts◦ Also for patients with known history of CAD◦ Gold standard for coronary evaluation

Diagnostic Testing

Circulation.or.kr

IVUS- small ultrasound catheter is inserted in the coronary artery to image the vessel and assess plaque◦ Can differentiate between fibrous and calcified plaque◦ Virtual histology

Diagnostic TestingIntravascular Ultrasound

Ptca.org

Technically: the ratio of blood flow in a stenotic artery to normal flow

Essentially: a stress test on a specific artery◦ Flow is measured by a special guidewire, using flow

measurements beyond the lesion and comparing them with flow before the lesion

◦ IV infusion of Adenosine is used to increase HR ◦ Ratio is calculated from a 2-3 minute period◦ Normal value = 1.0◦ Abnormal value = <0.75

Diagnostic TestingFractional Flow Reserve (FFR)

Treatment of CAD

Medical treatment- managing the patient’s medications to help alleviate symptoms

Percutaneous Coronary Intervention (PCI)- used in various situations, from single lesions to complex, high-risk multi vessel disease

Nhlbi.nih.gov

Treatment of CAD Coronary Artery Bypass Grafting- most

often used for severe multi vessel disease and diabetic patients

Beaumonthospitals.com

We’ve come a long way from the first accidental coronary angiogram in 1958…

Diagnosis and treatments continue to evolve

Coronary Arteries Summary

Peripheral Arterial Disease (PAD)

◦ Same arterial anatomy and disease process, but most patients (with exception of CVA) tend to wait much longer to seek treatment

May mimic arthritis, neuropathy Symptoms attributed to “old age”

What about Peripheral Vascular Disease?

Claudication- leg pain with walking that resolves at rest

Decreased temperature of extremity

Non-healing wounds

Symptoms of LE PAD

Sudden numbness or weakness, especially on one side

Sudden confusion, trouble speaking

Sudden trouble seeing in one or both eyes

Sudden dizziness, loss of balance and coordination

Sudden severe headache

Symptoms of CVA

Ultrasound/Doppler studies

MRI/MRA

CT/CTA

Angiography

Diagnostic Testing for PAD

Medications

Percutaneous Transluminal Angioplasty (PTA) with or without stent placement

Atherectomy

Bypass surgery

Treatment of PAD

Interventions done for high-risk, asymptomatic or symptomatic patients (depends on clinical study enrollment)

All patients must be enrolled in a research study to receive a stent

◦ Typical criteria: asymptomatic with >80% stenosis by ultrasound, or symptomatic with >50% stenosis and at least one high-risk factor, such as age>80 years, CHF, severe COPD, previous CEA with restenosis, previous radiation therapy or neck surgery, lesion location

Carotids

Cleveland Clinic Heart and Vascular Institute

Code Stroke

An Interdisciplinary effort to get treatment started for stroke victims ASAP

◦ Emcompasses: ED assessment, activation of Code Stroke protocol, Neurology consults, CT scans, Interventional Cardiology consults, thrombolytic treatment if indicated, invasive intervention if indicated

Renals Interventions performed for poorly controlled

hypertension or poor renal function

Rivascularinstitute.com

Interventions performed for claudication, critical limb ischemia (non healing wounds), and limb salvage

Lower Extremity

Radiologyrsnajnls.org

PAD

Basically, if we can get a catheter to an artery, we can take a picture and potentially intervene!

◦ Mesenterics◦ Subclavians◦ ETC…

Fast growing segment of cardiac cath lab procedures

Percutaneous treatments are constantly being developed

PAD Summary

Cvphysiology.com Heartsite.com NEJM, Vol. 360 No.3 Ncbi.nlm.nih.gov Encyclopedia Brittanica Med.yale.edu Johnson.com Bocacardiology.com Brighamandwomens.org Nature Publishing Group Emedicine.medscape.com

Sources

64ctscan.com Csmc.edu Circulation.or.kr Ptca.org Beaumonthospitals.com Nhlbi.nih.gov Cleveland Clinic Heart and Vascular Institute Rivascularinstitute.com Radiologyrsnajnls.org Imagingeconomics.com How-to-draw-cartoons-online.com

Sources