Cardiology: Cardiac Catheterization

Cardiac catheterization Notes

This is not necessarily the same as coronary angiography, although the two terms are sometimes used interchangeably.

Cardiac catheterisation is the process by which you gain catheter access to the veins or arteries of the heart. Thus, in the procedures of coronary angiography, and angioplasty, you perform cardiac catheterisation as part of the procedure.

Reasons for catheterisation

-          Injection of dye in angiography

-          Measurement of intracardiac pressures and oxygen saturations

-          Passage of electrophysiological instruments

-          Passage of angioplasty and valvuloplasty balloons

During catheterisation, the patient is usually awake throughout, and the catheter is guided by fluoroscopy.

Left heart catheterisation

This is performed via an arterial route. The catheter is usually inserted into the femoral artery (again, brachial artery is sometimes used), and then passed up the artery, and into the aorta. Eventually it reaches the aortic arch, and can be passed directly into the left ventricle.

-          The radial artery is gaining favour as a preferred site – as some studies report fewere complications. it is also useful when there is femoral artery stenosis, or obesity obscures natural landmarks used to identify the femoral artery.

Uses

Assessment of:

-           left ventricular function

-          Severity of mitral and aortic valve disease

-          Outflow tract obstruction

-          Extent of coronary artery disease

-          Allows biopsies to be taken – e.g. in cardiomyopathies

-          Allows electrophysical provocation studies – e.g. for VT

-          Allow placement of stents (PCI)

-          Allows balloon valvotomy

Right sided catheterisation

-          This is performed via the venous route. The catheter is inserted via the femoral, internal jugular, subclavian or forearm veins.

Uses

Allows:

-          Measurement of cardiac output

-          Measurement of left ventricular filling pressure

-          Measurement of pulmonary artery wedge pressure (PWP) – this is the pressure in the pulmonary artery distal to an occlusion of the artery. This is useful because it provides an estimation of the left atrial pressure. It is useful in determining the cause of acute pulmonary oedema. This is likely to be present if there is a PWP >20mmHg. Normal physiological pressure is 6-12mmHg.

-          Direct thrombolysis of the pulmonary artery for massive pulmonary embolism

-          Insertion of electrodes for cardiac pacemaker devices

Measurement of the PWP can involve the insertion of a Swan-Ganz catheter (pulmonary artery catheter). This catheter is purely diagnostic and is used to monitor left and right ventricular function. This catheter is usually inserted via the internal jugular or subclavian vein.

Indications for Swan-Ganz:

-          Shock (cardiogenic vs non-cardiogenic)

-          Respiratory distresses

-          Complicated MI

-          Monitoring effects of drugs (e.g. ionotropes)

-          Assesing fluid requirements

-          Thrombolysis for PE

The procedure

-          Not normally painful. Patient may feel a warm flushing sensation when the dye is used

-          Patients may be given some sedation if they feel anxious – normally this is diazepam (did you know this is Valium?!)

-          Patients with renal impairment (creatinine of over 200) will require 1L of IV saline at least 1 hour before the treatment to reduce the risk of x-ray contrast nephropathy

Contraindications

There are no absolute contraindications. However, you still have to consider the relative risks for each patient. If they have a large number of relative risks you might want to reconsider giving the catheter. These include:

-          Severe hypertension

-          Shock

-          Severe anaemia

-          Acute renal failure

-          Severe congestive cardiac failure

-          Allergy to contrast

-          Active infection or PUO

Also remember that catheterisation is part of other procedures (e.g. PCI) and thus not always just done on its own.

Complications

-          Haemorrhage from entry site

-          False aneurysm – this would need to be confirmed by ultrasound

-          Dye reaction

-          Infection

-          Angina and MI

-          Arrhythmias

-          Pericardial tamponade

-          Stroke

Notes by Tom Leach

Cardiology: Bypass Surgery (CABG)

By-pass surgery - CABG

Along with angioplasty this is the other coronary revascularisation technique used for the treatment of IHD (ischaemic heart disease).

Indications

-          Various studies have shown that high and medium risk patients can benefit from CABG, but there is no benefit to low risk patients.

o   The greatest degree of benefit is for those with LAD disease and 1/3 artery disease. Those with only one artery involved (and it is not the LAD) have less benefit

o   The benefits are reduced the longer you leave it between identifying those who would benefit, and carrying out the surgery.

PCI or CABG?

Not that – (according to the oxford handbook) – PCI has no effect on mortality, but CABG does!

-          Single lesions in nice straight vessels – PCI

-          Calcified lesion is tortuous vessels – CABG

-          LAD – CABG

-          Other single or double vessel involvement – PCI

-          Strongly positive ETT – CABG

Single, double triple?

This refers to the number of coronary arteries bypassed by the procedure. This however, does not necessarily reflect the severity of the disease. For example somebody may have very severe disease in one artery, whilst somebody else may have less severe disease, but spread over 3 arteries.

Procedure

-          Normally performed through a mid sternal inscision (medial sternotomy)

-          Veins are usually harvested from the saphenous vein of the legs – however, arteries may also be used, and arteries tend to give better results. This often occurs after the thorax has been opened and the surgeon has examined the arteries.

o   Arteries that can be used include; internal thoracic arteries (internal mammary), gastro-epiploic, inferior epigastric, radial artery.

o   Over 75% of patients have 3 grafts or more – at least one of these grafts is usually an artery

o   After 10 years, 83% of internal thoracic grafts are still patent, but only 41% of saphenous grafts.

-          The arteries to be by-passed are reviewed an angiography by the surgeon before the procedure.

-          Most surgeons prefer to perform the operation with cardioplegia. This is where the heart is manually stopped during an operation. It usually involves cooling the heart to around 34’C (mild hypothermia), before injecting cold crystalloid cardioplegic solution into the coronary circulation. This induces asystole but it also protects the myocardium from damage.

o   Antegrade cardioplegia – this is where the solution is introduced via the aortic root

o   Retrograde cardioplegia – this is where the solution is introduced via the coronary sinus

o   During cardioplegia, blood is diverted from the SVC and IVC via venous cannulae to a heart lung machine. This device both oxygenates and pumps the blood, as well as removing CO2.

o   Many surgeons also use an aortic cross clamp. This is a device that goes across the aorta and limits the systemic circulation.

o   During the operation the heart may be cooled to 15-20’. This slows down the metabolism of the heart and thus reduces the risk of damage to the myocardium.

o   Blood may be injected into the coronary arteries in a bid to reduce myocardium damage if the surgery last longer than ½ hour.

Operating without a pump – off pump coronary artery bypass grafting (OFCAB)

Developed in the 1990’s, this is being increasingly used. it has shorter procedure times and fewer complications.

Prognosis

-          A successful graft lasts about 10-15 years.

-          The surgery decreases the risk of death from CVD. However, 5 years after the surgery, the risk is about the same as somebody who has always been managed on drug treatments

-          The age of the patients affects the prognosis – generally, the younger the patient the better the prognosis, and longer the graft will be viable for.

-          The surgery significantly increases the quality of life, reduces symptoms, and increases exercise tolerance, as well as reducing the need for anti-anginal medications.

-          75% of patients are free of ischaemic events at 5 years. This is around 50% at 10 years

-          At 10 years:

o   Those who had a saphenous graft have no benefit over those on medical therapy

o   Those who had an arterial graft do still have benefit

-          The greatest benefit is to those with left main stem disease.

-          Women, on average, have worse outcomes than men. This is thought to be the result of a combination of factors, including; smaller coronary arteries, higher age at operation.

Complications

-          Death – (1-3%) – the risk of this is increased in those that are:

o   Smokers

o   Overweight

o   Obese

o   Diabetic

o   Female

o   Older

o   Short (height)

o   Having an emergence operation for an acute coronary syndrome

-          MI – 2%

-          Ventricular arrhythmias – such as broad complex tachycardia

-          Stroke – 2%. Reducing the amount of handling of the aorta can reduce the risk of embolism. The risk of stroke is also higher in those that have carotid artery stenosis.

-          Bleeding – clopidogrel and aspirin should be stopped 7 days before surgery. Note that in PCI, they are often actually used during and after surgery!

o   CABG seems to increase the resistance of patients to aspirin. Thus the drug is not as effective in these patients due to increased cell turnover.

-          Cognitive decline – has been reported in many patients but is difficult to measure. It is often mild and will reverse several months after treatment.

Long-term management

-          Cessation of smoking

-          Aspirin

-          ACE inhibitor

-          Beta-blocker

-          Statin

-          Control of BP

-          Control of diabetes

-         Weight and exercise management

Notes by Tom Leach

Cardiology: Angioplasty (PCI)

Angioplasty (percutaneous coronary intervention - PCI) Notes

This is also sometimes called PTCA - Percutaneous Transluminal Coronary Angioplasty

This procedure is able to open partially closed vessels before they become totally occluded. The patient is awake during the procedure. They may experience short periods of pain (explained below), but generally should not feel too uncomfortable. They may be given a sedative if they feel anxious.

 

***ANGIOPLASTY DOES NOT IMPROVE LONG TERM OUTCOME – it does not prolong life*** - it is purely for symptom relief. On the other hand, CABG does reduce MI related mortality, and can prolong life.

 

It is a coronary revascularisation technique – the other one of these being CABG.

 

Indications

-          STEMI (ST elevation MI) acute coronary syndrome – PCI is the preferred treatment – it is preferred over THROMBOLYSIS – however, many centres don’t offer PCI, thus thrombolysis may be used instead. It can also be used in STEMI when thrombolysis is contra-indicated.

-          Stable angina – should only be used in:

o   Single or double vessel disease – i.e. disease only involving 1 or 2 of the coronary arteries

o   Triple vessel disease who are not suitable for CABG

 

 

Procedure

This does not involve major surgery.

-          A balloon tipped catheter is entered into the body. This commonly enters via the femoral artery, or radial artery (in the past, the brachial artery was also used, but this is now rare). the artery is opened with an introducer needle, and this part of the procedure is called percutaneous access. Normally, the patient has had some local anaesthetic, so that they cannot feel this process.

-          Open access to this artery is gained, and a ‘sheath introducer’ essentially holds the artery open. Then a guiding catheter is placed in the artery, and passed all the way up to the opening of the coronary artery.

o   This guiding catheter also sometimes allows for radiopaque dies to be passed through the coronary arteries to see where the larges section of narrowing is. Usually the dye used is iodine-based.

-          There is then an x-ray to see the opaque dye. The cardiologist will then select an appropriately sized balloon tipped catheter for this particular patient. Heparin is given before the catheter is inserted.

-          The balloon tipped catheter is then inserted and guided into place using x-ray, to the optimum position of the most occlusion of the artery. The balloon is inflated, and often a stent is placed in the artery.

o   It can take 30-60 seconds to inflate the balloon. This process may occlude the coronary artery, and so for a short time, the patient may feel an angina type pain. They may be given opiates for this pain

o   The stent is often on the outside of the balloon, and the stent is expanded by the pressure of the inflating balloon.

o   The procedure may be repeated in several locations within the artery.

o   A sedative may be given before the procedure if the patient feels anxious.

 

 

Factors to consider on an individual basis:

-          Patients on warfarin or heparin may have to stop therapy 2-3 days before the treatment to prevent excessive bleeding from the femoral artery / site of catheter insertion. Obviously this does not apply to patients having this done as an emergency procedure!

-          Patients may be asked not to eat for several hours before the procedure

-          Insulin dependent diabetics may have to alter their insulin regimen on the day of treatment

 

The procedure lasts about 30 minutes. This is longer if more than one part of the artery is to be widened

Patients may need to stay in hospital overnight for observation following the procedure

 

 

Efficacy

-          The treatment is 90% successful in reducing the severity of angina. However – it cannot be used for all people with angina – it is not suitable for those with lots of narrowed sections of artery.

-          Over ¾ of patients have no ischaemic heart disease symptoms for several years afterwards (although the symptoms often return again later – in which case CABG may be required)

-          Bloodflow through the affected artery is often increased 3-4x

 

Afterwards

-          Patients should avoid any heavy activities (e.g. lifting or heavy exercise) for 1 week

-          There will be a small wound at the site of entry of the catheter

-          You should not drive for 1 week after the procedure

-          Patients with an HGV liscence – will need to consult the DVLA about driving a bus or a lorry after having an angioplasty.

o   Angina normally disqualifies drivers from driving HGV’s – however, 6 weeks after a PCI, the patient may take an ETT, and if they pass, then they may be allowed their licence back.

-          Patient are often able to go home the same day, although they may be kept in for observation overnight

-          Patients should take antiplatelet therapy:

o   PCI in STEMI - Long term aspirin, and clopidogrel 75mg daily for 1 month

o   PCI in stable angina – long term aspirin

 

Complications

-          Bruising at the entry site

-          Infection at the entry site (consult GP if the entry site becomes red and painful – they will probably get antibiotics)

-          Failure to stretch the artery (1 in 20 cases) – these patients may instead be suitable for a coronary artery bypass graft. However, this is more serious, and thus it is probably best to try angioplasty first.

-          Hypersensitivity to the dye

-          Serious complications:

o   Blockage of the coronary artery (1 in 100). These patients will be taken for emergency bypass surgery.

o   MI – (less than 1%) – will require emergency CABG

o   Damage to coronary artery by the catheter – less than 0.5%. treated surgically

o   Stroke – 0.5%

o   Death – 0.2%

o   Regrowth of the atheroma over the stent – this occurs in 25-60% of cases. The chance of restenosis depends on other risk factors, such as diabetes. Newer stents are being developed that are coated with products that prevent the growth of atheroma. These are called drug eluting stents (DES). However, these are controversial, as although they halve the rate of plaque formation, they have a higher rate of stent failure, and they do not improve long term survival. The drugs they give off are basically anti-inflammatory. This also reduces normal healing after placing the stent, hence the reason why these patients need to be on clopidogrel for longer.  

§    They are also more expensive, both in manufacture, and due to the longer dose of clopidogrel that they require.

o   Cardiac tamponade – 0.5%

o   Systemic bleeding – 0.5%

 

Compared to CABG – for stable angina

-          PCI is less invasive and less costly

o   However – in the long term these benefits are outweighed by the fact the treatment needs to be re-done.

-          Recent evidence suggests that overall, PCI is less cost effective than CABG, although obviously, it needs to be assessed on a case by case basis

 

Compared to thrombolysis for acute coronary artery syndrome

-          PCI has lower death rates, lower recurrent ischaemia, and fewer major complications in STEMI

-          The evidence suggests it is generally more effective than thrombolysis

 

 

Finally – there is a variation of the procedure using an argon laser beam - and the laser is able to dissolve the plaque.

 

 

Notes by Tom Leach

 

 

Cardiology: Angiography

Angiography Notes

This is a technique used to visualise the inside of vessels, in this case, those of the heart. 

It is basically used to assess the extent of angina. It involves cardiac catheterisation. Once the catheter is in place, an iodine based dye is injected into the coronary vessels, and the extent of narrowing (atheroma) can be asses by –xray.

-          The angiogram is actually recorded as a moving picture as many low-dose x-rays are taken in quick succession.

Procedure

-          The patient will lie flat on a couch, with the x-ray machine above them. The catheter will be passed to the opening of the cardiac vessels from the aorta.

o   Patients may feel an occasional missed or extra heart beat during the procedure – this is normal.

-          Basically – its exactly the same as catheterisation! – except that a bit of dye is quirted in and x-rays taken.

-          The test normally lasts about 30 minutes.

Complications

-          Mortality is about 1%

-          May be some bruising at the entry site

-          Some patients may have stitches at the entry site to seal it up

-          May have a false aneurysm at the femoral artery if this was used as the entry site

-          May get angina-type pain during the procedure

-          May get an infection at the site of entry

-          May have a warm flushing feeling when the dye is injected

-          Stroke and MI are possible but rare

-          Also rarely, the coronary artery may be damaged and emergency bypass may need to be performed 

Notes by Tom Leach

Cardiology: Management of the Acutely Ill Patient

Cardiology: Management of the Acutely Ill Patient NOTES

Ok, so here’s the scenario. You are an FY1. It’s your first on call shift. It’s the middle of the night. A nurse bleeps you and says… ‘My patient’s ‘going off’ get here quick!’. What do you do?!

-          This kind of situation results in loads of cardiac arrests, and deaths – but many of these are avoidable, with early detection of disordered physiology

o   when a patient goes off its often the case that for the past few hours there have been signs… e.g. their BP has dropped, respiratory rate has increased, and as a result their EWS has increased. The EWS is an attempt to address these patients as soon as possible, to avoid arrests and deaths.

DON’T PANIC! Just got back to your ABC’s….

When you first get to the patient (or even better, over the phone when the nurse calls) find out a bit about the patient: name, age, why are they in hospital, what has happened?

-          If the patient is conscious, ask them how they are feeling, if they have any pain, and where is the pain. If they respond, it’s fairly safe to assume they have a patent airway…

-          A – Airway

o   Check it is patent – to head tilt + chin lift or if this is not possible, jaw thrust

§ In an obstructed airway, there is often a characteristic method breathing, whereby on attempted inspiration, the abdomen expands, and the chest is drawn inwards.

-          B – Breathing

o   Look

§ Check the O2 sats

§ Check the respiratory rate

§ Look for chest expansion

·         If you can’t see any, consider feeling for breaths- could do this simultaneously to listening

§ Look for any signs of cyanosis

o   Listen

§ Listen to the chest

·         You might want to listen to the heart as well, just to speed things up

o   Feel       

§ Chest Expansion

§ Percuss

-          Circulation

o   Look

§ Temperature / colour of extremities

§ Check capillary return

o   Listen

§ BP – likely this will e done by nurse / automated machine

§ Heart sounds – you probably listened when listening for breath sounds

o   Feel

§ Pulse

·         Rate and character – probably already know the rate from the sats monitor

·         Check that radial is present – if systolic BP <70, this will likely be absent

·         If absent, feel for brachial, then carotid

-          D – Disability

o   Basically, check their conscious level. There isn’t time for a GCS, so instead, use AVPU:

§ A – Alert

§ V – Voice

§ P – Pain

§ U – Unresponsive

·         If the patient scores a ‘U’, this is equivalent to <8 on GCS – and the patient requires intubation!

o   Check the pupils

§ Indicate level of consciousness and head injury

§ In cases of head injury, avoid morphine for pain relief – it is contraindicated as it can alter papillary response

o   Check the glucose in any patient with impaired consciousness – its really easy, and if hypoglycaemia is the cause, it is easily corrected

-          E – Exposure

o   Expose the whole patient to look for any obvious signs –e.g. melaena, wound, rashes etc

o   Everything else

§ Full examination plus as much Hx as you can get from the patient, nurse and notes

§ Get an ECG

§ Check BP (if not already)

§ Give O2

§ Give fluids

§ Get bloods – including blood group for possible future transfusion

·         Taking blood from the acutely unwell patient – you should not ever use a cannula that has had fluid going through it – as the fluid will dilute the blood and give useless results. Use the arm that has no cannula. If both arms have cannulas, stop the fluid in one arm, wait ten minutes, then take blood from a separate site on that arm. If it is not sensible to stop the fluids, then take a femoral vein sample.

§ Consider catheter to monitor output

§ Consider ABG

·         Most useful for getting the pH. Hypovolaemia commonly causes a metabolic acidosis resulting from peripheral anaerobic metabolism – producing lactic acid.

-          R – Reassess

o   This is really important. keep going through your ABC’s to see if your interventions are having any effect!

-          P – Plan

o   Consider further investigations, e.g. CXR

o   Call for assistance. First port of call will likely be the surgical / medical SHO on call, but you might want to call the reg

o   When sending off your bloods, you should call ahead and state that they are urgent, to get the results back sooner.

Making a diagnosis is not critically important – you are just trying to stabilise and keep the patient alive at the moment. Obviously having an idea of the diagnosis helps direct what blood / investigations you will order, and who to call for help.

Giving fluids to the acutely ill patient

-          Get two wide bore (grey, or as big as you can manage) cannulas in ASAP

-          The actual fluid given is not that important. There is controversy over whether colloid or crystalloid is best, but it probably doesn’t make much difference. Avoid Potassium until you have blood results back! e.g. 0.9% saline or gelofusine will be fine

-          Consider how much to give. If your patient is in shock, then you should give a fluid challenge

-          FLUID CHALLENGE

o   Give your patient 500ml of 0.9% saline, as quickly as possible (e.g. over 5-10 minutes)

§ If the fluid doesn’t go in quick enough, then you can use a pressure bag to squeeze the fluid bag!

o   Recheck the BP / pulse / AVPU

§ If these have improved – GREAT! – your patient is in a non-cardiogenic shock, and you should continue to give more fluids. You can use both cannulas at the same time if you think it is necessary, and give the fluids as fast as possible (just leave the valve open in the giving set, and possibly use a pressure bag).

·         You can give up to 2-3L like this. If your patient is still in shock (aim for systolic >90), then you might now have to consider blood transfusion (hopefully your HB and blood group results are back from the lab!).

o   Remember! – when checking the Hb before transfusion, Hb is a measure of concentration. So if you have not given any luids, but your patient has lost blood, their Hb concentration will still be the same as if they had lost no blood! But if you have given fluids to replace lost blood, you have diluted their blood, and as a result, has lowered their Hb

§ If these have no improved – your patient is likely to be in cardiogenic shock – don’t give any more fluids – as this will likely only fluid overload the patient.               

·         If BP is high, then heart failure is likely, and give frusemide 20mg and wait for response – make sure you have catheterised to measure urine output first

  

Notes by Tom Leach