 \200 NSAIDs are the mainstay. Ibuprofen is well tolerated and may be used if the pain does not decrease within 48 hours There is evidence to support that either used as \200 should be given only if bacterial infection is suspected. CARDIAC TAMPONADE: PRESENTATION 51 Cardiac tamponade: presentation Cardiac tamponade occurs when a pericardial effusion causes hemo- dynamically signi \201 cant cardiac compression. The presentation depends on the sp eed with which \202 uid accumulates within the pericardium. Acute tamponade may occur with 100 \200\223200 mL in a relatively restricted pericardial sac. Chronic pericardial collections may contain up to 1000 mL of \202 uid with- out clinical tamponade. Causes Acute tamponade \200 Cardiac trauma \200 Iatrogenic \200 \200 \200 Aortic dissection Spontaneous bleed \200 Anticoagulation \200 Uremia \200 Thrombocytopenia C ardiac rupture post-MI Subacute tamponade \200 Malignant disease \200 Idiopathic pericarditis \200 Uremia \200 Infections \200 Bacterial \200 Radiation Hypothyroidism Postpericardiotomy SLE Ot her autoimmune disease Post-cardiac surgery Post-cardiac catheterization Post-pacing/EP study \200 Tuberculosis \200 \200 \200 \200 Presentation Patients commonly present with either cardiac arrest (commonly electrical mech anical dissociation) or hypotension, confusion, stupor, and shock. Patients who develop cardiac tamponade slowly are usually acutely unwell, but not in extremis. Their main symptoms include the following: \200 \200 \200 Shortness of breath, leading to air hunger at rest. There may be a preceding history of che st discomfort. Symptoms resulting from compression of adjacent structures by a large effusi on (i.e., dysphagia, cough, hoarseness, or hiccough). There may be symptoms due to the unde rlying cause. Insidious development may present with complications of tamponade, including renal failure, liver and/or mesenteric ischemia, and abdominal plethora. \200 Important physical signs Most physical \201 ndings are nonspeci \201 c and include the f ollowing: \200 \200 \200 Tachycardia (except in hypothyroidism and uremia). Hypotension ( shock) with postural hyp otension. Raised JVP (often >10 cm) with a prominent systolic absent diastolic y descent (s ee Box 1.10). If the JVP is visible and either remains static or rises with inspiration, it indicates concomitant pericardial constriction (Kussmaul \200\231s sign). Auscultation may reveal diminished heart sounds. Pericardial rub may be present and suggests a small perica rdial collection. x descent and CHAPTER 1 Cardiovascular emergencies 52 Look for pulsus paradoxus (a decrease in the palpable pulse and SBP of >10 mmHg on inspirat ion). This may be so marked that the pulse and Korotkoff sounds may be completely lost duri ng inspiration. This can be measured using a BP cuff 1 or arterial catheter if in situ alre ady. Other conditions that can cause a pulsus paradoxus include acute hypotension, obstruct ive airways disease, and pulmonary embolus. Other physical signs include cool extremities (ears, nose), tachypnea, hep- atomegaly, and signs of underlying cause of the pericardial effusion. Box 1.10 Causes of hypotension with a raised JVP \200 \200 \200 \200 \200 \200 \200 \200 \200 Cardiac tamponade Constrictive pericarditis Restrictive cardiomyopathy Severe biventricular failure Right ventricular infarction Pulmonary embolism Tension pneumothorax Acute severe asthma Malignant superior vena cava (SVC) obstruction and sepsis (e.g., lymphoma) 1 Teaching point: To establish presence of pulsus paradoxus noninvasively, in \202 ate BP cuff to 15 mmHg above highest systolic pressure. De \202 ate cuff gradually until \201 r st beats are heard and hold pressure at that level concentrating on disappearance and reapp earance of sounds with respiration (bump-bump, silence-silence, bump-bump, where noise re \202 ects expiration). Continue to de \202 ate slowly, paying attention to the same patter n until all beats are audible. The difference between the initial and \201 nal pressure s hould be >10 mmHg when paradox is present. CARDIAC TAMPONADE: MANAGEMENT 53 Cardiac tamponade: management Tamponade should be suspected in patients with hypotension, e levated venous pressure, falling BP, iHR and iRR (with clear chest), and pulsus paradoxus, especially if predisposing factors are present. Investigations \200 CXR: the heart size may be normal (e.g., in acute hemopericardium following cardiac trauma) . With slower accumulation of pericardial \202 uid (>250 mL) the cardiac silhouette will enlarge with a globular appearance. The size of the effusion is unrelated to its hemodynami c signi \201 cance. Look for signs of pulmonary edema. ECG and variable ST-segment changes . With large effusions, electrical alternans may be present with beat-to-beat variation in the QRS morphology possibly resulting form the movement of the heart within the pericardial effusion. Echocardiography diagnosis of tamponade is a clinical one. ECHO signs highly sug gestive of tamponade include 1) chamber collapse during diastole (RA, RV, RV out \202 ow t ract), 2) marked variation in transvalvular \202 ow, and 3) dilated IVC with little or no diameter change on respiration. usually shows a sinus tachycardia, with low-voltage complexes con \201 rms presence of a pericardial effusion. The If available, examine the central venous pressure trace for the characteris- tic exaggerate d x descent and absent y descent. Management Following con \201 rmation of the diagnosis: \200 While preparing for drainage of the pericardial \202 uid, the patient \200\231s circulati on may temporarily be supported by loading with IV colloid (500 \200\2231000 mL stat) and s tarting inotropes (i.e., adrenaline). The effusion should be urgently drained (see p. 75 fo r pericardio- centesis), guided by ECHO or \202 uoroscopy. In the event of circulatory co llapse, drainage must happen immediately without imaging. Surgical drainage is indicated if the effusion is secondary to trauma. Avoid intubation and positive pressure ventilation as this reduces CO. In patients with cardiac arrest, chest compression has little or no value , as there is no room for additional \201 lling. Uremic patients will also need dialysis. The cause of the effusion should be established (see p. 309). Pericardial \202 uid shoul d be sent for cytology, microbiology including TB, virology, and, if appropriate, Hb, gluco se, and amylase. \200 \200 \200 Further management is of the underlying cause. CHAPTER 1 Cardiovascular emergencies 54 Special cases Recurrent pericardial effusion In some cases, pericardial effusion recurs. Th is requires either a change in the treatment of the underlying cause or a formal surgical d rainage pro- cedure such as a surgical pericardial window or pericardiectomy. Low-pressure tamponade This is seen in the setting of dehydration. The JVP is not raised, r ight atrial pressure is normal, and tamponade occurs even with small volumes of pericardial \202 uid. \200 \200 The patient may respond well to IV \202 uids. If there is a signi \201 cant pericardial collection, this should be drained. CENTRAL LINE INSERTION 55 Practical procedures Central line insertion Check list of required materials \200 Sterile dressing pack and gloves \200 10 mL and 5 mL syringe (21G) and (25G) needles \200 Loca l anesthetic (e.g., 2% lidocaine) \200 Central line (e.g., 16G long Abbocath \200 Salin e \202 ush \200 Silk suture and needle \200 No 11 scalpel blade \200 Sterile occlus ive dressing (e.g., Tegaderm or Seldinger catheter) ) Risks \200 \200 \200 \200 \200 \200 Arterial puncture (remove and apply local pressure) Pneumothorax (insert chest drain or asp irate if required) Hemothorax Chylothorax (mainly left subclavian lines) Infection (local, septicemia, bacterial endocarditis) Brachial plexus or cervical root damage (over in \201 ltration with local anesthetic) Arrhythmias General procedure The basic technique is the same regardless of the type of vein being can- nulated (see Fig. 1.6). \200 \200 \200 Lay the patient supine ( head-down tilt). Turn the patient \200\231s head away from the s ide you wish to cannulate. Clean the skin with chlorhexidine \200\224from the angle of the jaw to the clavicle for internal jugular vein (IJV) cannulation and from the midline to axi lla for the subclavian approach. Use the full drapes to isolate the sterile \201 eld. Flu sh the lumen of the central line with saline. Identify your landmarks. In \201 ltrate skin and subcutaneous tissue with local anesthetic. Have the introducer needle and Seldinger gu ide wire within easy reach so that you can reach them with one hand without having to relea se your other hand. Your \201 ngers may be distorting the anatomy slightly, making access to the vein easier, and if released it may prove dif \201 cult to relocate the vein. With the introducer needle in the vein, check that you can aspirate blood freely. Use the hand that was marking the landmarks to immobilize the needle relative to the skin and mandible o r clavicle. Remove the syringe and pass the guide wire into the vein; it should pass freely . If there is resistance, remove the wire, check that the needle is still within the lumen, and try again. Remove the needle, leaving the wire within the vein, and observe for any ar rhythmia from the wire \200\234tickling \200\235 the atrium or ventricle. \200 \200 \200 \200 CHAPTER 1 Cardiovascular emergencies 56 With a No.11 blade, make a nick in the skin where the wire enters to facilitate dilatation of the subcutaneous tissues. Pass the dilator over the wire and remove, leaving the wire in situ. Pass the central line over the wire into the vein. Remove the guide wire, \202 ush the lumen with fresh saline, and close off to air. Suture the line in place and cover the skin penetration site with a sterile occlusive dressing. Box 1.11 Measuring the CVP \200\224tips and pitfalls \200 When asked to see a patient at night with an abnormal CVP reading, it is good to always rec heck the zero and the reading yourself. Always do measurements with the mid-axillary point as the zero reference. Sitting the patient up will drop the central \201 lling pressure ( pooling in the veins). Look at the rate and character of the venous pressure tracing. It sh ould fall to its value quickly and swing with respiration. If it fails to fall quickly, con sider whether the line is open (i.e., saline running in), blocked with blood clot, position al (up against vessel wall; ask patient to take some deep breaths), arterial blood (blood t racks back up the line). Raise the whole dripstand (if you are strong), and make sure that the level falls. If it falls when the whole stand is elevated, it may be that the CVP is ve ry high. It is easier, and safer, to cannulate a central vein with the patient supine or he ad down. There is an increased risk of air embolus if the patient is semi-recumbent. Sternal notch Subclavian vein and artery Clavicle Common carotid artery (under muscle) Internal jugular vein Sternocleidomastoid muscle Syringe Figure 1.6 Technique for catheterization at the internal jugular and subclavian sites. Repr oduced with permission from McGee DC, Gould MK (2003). N Engl J Med 348(12):1123 \200\22311 33. Copyright 2003 Massachusetts Medical Society. All rights reserved. INTERNAL JUGULAR VEIN CANNULATION 57 Internal jugular vein cannulation The IJV runs just posterolateral to the carotid artery wi thin the carotid sheath and lies medial to the sternocleidomastoid (SCM) in the upper part of the neck, between the two heads of SCM in its medial portion, and enters the subclavian vein near the medial border of the anterior scalene muscle (see Fig. 1.7). There are three basic approaches to IJV cannulation: medial to (SCM), between the two heads of SCM, or lateral to SCM. The approach used var- ies and depends on the experience of the operator and the institution. \200 Locate the carotid artery between the sternal and clavicular heads of the SCM at the level of the thyroid cartilage; the IJV lies just lateral and parallel to it. Keeping the \201 ngers of one hand on the carotid pulsation, in \201 ltrate the skin with LA thoroughly, ai ming just lateral to this and ensuring that you are not in a vein. Ideally, \201 rst loca te the vein with a 21G needle. Advance the needle at 45 to the skin, with gentle negative suction on the syringe, aiming for the ipsilateral nipple, lateral to the pulse. If you fa il to \201 nd the vein, withdraw the needle slowly, maintaining negative suction on the s yringe (you may have inadvertently have trans \201 xed the vein). Aim slightly more medial ly and try again. Once you have identi \201 ed the position of the vein, change to the syr inge with the introducer needle, cannulate the vein, and pass the guide wire into the vein. Tips and pitfalls Venous blood is dark, and arterial blood is pulsatile and bright red! Once you locate the vein, change to the syringe with the introducer needle, taking care not to release your \201 ngers from the pulse; they may be distorting the anatomy slightly, making access to the vein easier, and if released it may prove dif \201 cult to relocate t he vein. The guide wire should pass freely down the needle and into the vein. With the left IJV appr oach, there are several acute bends that need to be negotiated. If the guide wire keeps pas sing down the wrong route, ask your assistant to hold the patient \200\231s arms out at 90 to the bed, or even above the patient \200\231s head, to coax the guide wire down the cor rect path. For patients who are intubated or require respiratory support, it may be dif \201 cult to access the head of the bed. The anterior approach may be easier (see Fig. 1.7) and may be d one from the side of the bed (the left side of the bed for right-handed operators, using th e left hand to locate the pulse and the right to cannulate the vein). The IJV may also be readily cannulated with a long Abbocath . No guide wire is necessary, but as a result, misplacement is more common than with the Seldinger technique. When using an Abbocath , on cannulating the vein, remember to advance the sheath and needl e a few millimeters to allow the tip of the CHAPTER 1 Cardiovascular emergencies 58 plastic sheath ( 1 mm behind the tip of the beveled needle) to enter the vein. Holding the needle stationary, advance the sheath over it into the vein. Arrange for a CXR to con \201 rm the position of the line and rule out pneumothorax. Sternal head Sternal head Sternocleidomastoid muscle Clavicular head External jugular vein (a) Surface anatomy of external and internal jugular veins (b) Anterior approach: the chin is in the midline and the skin puncture is over the sternal head of SCM muscle (c) Central approach: the chin is turned away and the skin puncture is between the two head s of SCM muscle Figure 1.7 Internal jugular vein cannulation. SUBCLAVIAN VEIN CANNULATION 59 Subclavian vein cannulation The axillary vein becomes the subclavian vein (SCV) at the late ral bor- der of the \201 rst rib and extends for 3 \200\2234 cm just deep to the clavicle . It is joined by the ipsilateral IJV to become the brachiocephalic vein behind the sternoc lavicular joint. The subclavian artery and brachial plexus lie posteriorly separated from the vein by the sc alenus anterior muscle (see Fig. 1.8). The phrenic nerve and the internal mammary artery li e behind the medial portion of the SCV, and on the left lies the thoracic duct. Checklist \200 The patient should be in the Trendelenberg position. Select the point 1 cm below the juncti on of the medial third and middle third of the clavicle. If possible, place a bag of saline between the scapulae to extend the spine. Clean the skin with iodine or chlorhexidine. In \201 ltrate skin and subcutaneous tissue and periosteum of the inferior border of the clav icle with local anesthetic up to the hilt of the green (21G) needle, ensuring that it is no t in a vein. Insert the introducer needle with a 10 mL syringe, guiding gently under the cl avicle. It is safest to initially hit the clavicle and \200\234walk \200\235 the needle un der it until the inferior border is just cleared. In this way you keep the needle as super \201 cial to the dome of the pleura as possible. Once it has just skimmed underneath the c lavicle, advance it slowly toward the contralateral sternoclavicular joint, aspirating as y ou advance. Using this technique, the risk of pneumothorax is small, and success is high. O nce the venous blood is obtained, rotate the bevel of the needle toward the heart. This enc ourages the guide wire to pass down the brachiocephalic rather than up the IJV. The wire sh ould pass easily into the vein. If there is dif \201 culty, try advancing during the inspi ratory and expiratory phases of the respiratory cycle; do not force the wire. Observe for a rrhythmia. Once the guide wire is in place, nick the skin with a blade, remove the introduc er needle, and pass the dilator over the wire. When removing the dilator, note the directio n that it faces; it should be slightly curved downward. If it is slightly curved upward, th en it is likely that the wire has passed up into the IJV. The wire may be manipulated into the brachiocephalic vein under \202 uoroscopic control. If this is not available it is sa fer to remove the wire and start again. After removing the dilator, pass the central venous catheter over the guide wire, remove the guide wire, and secure as above. A CXR is mandato ry after subclavian-line insertion to exclude a pneumothorax and to con \201 rm satisfacto ry placement of the line, especially if \202 uoroscopy was not employed. \200 CHAPTER 1 Cardiovascular emergencies 60 Scalenus anterior muscle Subclavian artery Clavicle Phrenic nerve Subclavian vein 1st rib 2nd rib 3rd rib Figure 1.8 The subclavian vein and surrounding structures. PULMONARY ARTERY CATHETERIZATION 61 Pulmonary artery catheterization Indications Pulmonary artery (PA) catheters (Swan \200\223 Ganz catheters) allow direct measurement of a number of hemodynamic parameters that aid cli nical decision-making in critically ill patients (evaluate right and left ventricular funct ion, guide treatment, and provide prognostic information). Consider inserting a PA catheter in any critically ill patient, after discussion with an experienced physician, if the meas urements will in \202 uence decisions on therapy (and not just to reassure yourself). Careful and frequent clinical assessment of the patient should always accompany measurement s, and PA catheterization should not delay treat- ment of the patient. General indications (not a comprehensive list) include the following: Management of complic ated myocardial infarction Assessment and management of shock Assessment and management of respiratory distress (cardiogenic vs. noncardiogenic pulmonary edema) Evaluating effects of treatment in unstable patients (e.g., inotropes, vasodilators, mechanical ventilation, etc .) Delivering therapy (e.g., thrombolysis for pulmonary embolism, prostacyclin for pulmonar y hypertension, etc.) Assessment of \202 uid requirements in critically ill patients \200 \200 Equipment required Full resuscitation facilities should be available and the patient \200 \231s ECG should be continuously monitored. \200 Bag of saline for \202 ushing the catheter and transducer set for pressure monitoring. (C heck that your assistant is experienced in setting up the transducer system BEFORE you star t.) 8F introducer kit (prepackaged kits contain the introducer sheath and all the equipment required for central venous cannulation) PA catheter: commonly a triple lumen catheter, wh ich allows simultanous measurement of RA pressure (proximal port) and PA pressure (distal p ort) and incorporates a thermistor for measurement of cardiac output by thermodilution; and a balloon to facilitate \202 otation of the catheter. Check your catheter before you sta rt. Fluoroscopy is preferable, though not essential. General technique Do not attempt this without supervision if you are inexperienced. \200 \200 Observe strict aseptic technique using sterile drapes, etc. Insert the introducer sheath (a t least 8F in size) into either the internal jugular or subclavian vein in the standard way . Flush the sheath with saline and secure to the skin with sutures (see Fig. 1.9). Do not a ttach the plastic sterile expandable sheath to the introducer yet, but keep it sterile for use later once the catheter is in position (the catheter is easier to manipulate without th e plastic covering). CHAPTER 1 Cardiovascular emergencies 62 (a) (b) (c) Figure 1.9 Pulmonary artery catheterization. (a) The sheath and dilator are advanced into t he vein over the guide wire. A twisting motion makes insertion easier. (b) The guide wire a nd dilator are then removed. The sheath has a hemostatic valve at the end preventing leakag e of blood. (c) The PA catheter is then inserted through the introducer sheath into the vei n. Thread it onto the catheter and have it ready for use when the catheter is positioned. Flus h all the lumens of the PA catheter and attach the distal lumen to the pressure transducer. Check that the transducer is zeroed (conventionally to the mid-axillary point). Check the integrity of the balloon by in \202 ating it with the syringe provided (1 \200\2232 mL air ) and then de \202 ate the balloon. Insertion technique \200 Flush all the lumens of the PA catheter and attach the distal lumen to the pressure transdu cer. Check that the transducer is zeroed (conventionally to the mid-axillary point). Check the integrity of the balloon by in \202 ating it with the syringe provided and then de \202 ate the balloon. Lock the valve. PULMONARY ARTERY CATHETERIZATION 63 Pass the tip of the PA catheter through the plastic sheath, keeping the sheath compressed. The catheter is easier to manipulate without the sheath over it; once in position, extend t he sheath over the catheter to keep it sterile and lock in place. With the balloon de \202 ated, advance the tip of the catheter to approximately 10 \200\22315 cm from the right IJV or SCV, 15 \200\22320 cm from the left (the markings on the side of the catheter are at 10 cm intervals: 2 lines = 20 cm). Check that the pressure tracing is typical of the RA press ure (see Table 1.7 and Fig. 1.10). In \202 ate the balloon and advance the catheter gently . The \202 ow of blood will carry the balloon (and catheter) across the tricuspid valve, through the right ventricle and into the pulmonary artery (see Fig. 1.10). Watch the ECG tr acing closely while the catheter is advanced. The catheter commonly triggers runs of VT whe n crossing the tricuspid valve and through the RV. The VT is usually self-limiting but shou ld not be ignored. De \202 ate the balloon, pull back, and try again. If more than 15 cm o f catheter is advanced into the RV without the tip entering the PA, this suggests the cathe ter is coiling in the RV. De \202 ate the balloon, withdraw the catheter into the RA, rein \202 ate the balloon, and try again using clockwise torque while advancing in the ventric le, or \202 ushing the catheter with cold saline to stiffen the plastic. If this fails re peatedly, try under \202 uoroscopic guidance. As the tip passes into a distal branch of t he PA, the balloon will impact and not pass further \200\224the wedge position \200\224and the pressure tracing will change (see Fig. 1.10). De \202 ate the balloon and check that a typical PA tracing is obtained. If not, try \202 ushing the catheter lumen, and if that fails, withdraw the catheter until the tip is within the PA and begin again. Rein \202 ate the balloon slowly. If the pulmonary capillary wedge (PCW) pressure is seen before the bal loon is fully in \202 ated, it suggests that the tip has migrated further into the artery. De \202 ate the balloon, withdraw the catheter 1 \200\2232 cm, and try again. If the pres sure tracing \202 attens and then continues to rise, you have \200\234overwedged. \200 \235 Immediately de \202 ate the balloon, pull back the catheter 1 \200\2232 cm, and start again. When a stable position has been achieved, extend the plastic sheath over the cathet er and secure it to the introducer sheath. Clean any blood from the skin insertion site wit h antiseptic and secure a coil of the PA catheter to the patient \200\231s chest to avoid i nadvertent removal. Dress the catheter sterilely. Obtain a CXR to check the position of the catheter and rule out pneumothorax. The tip of the catheter should ideally be no more than 3 \200\2235 cm from the midline. Tips and pitfalls \200 \200 \200 \200 Never withdraw the catheter with the balloon in \202 ated. Never advance the catheter with the balloon de \202 ated. Never inject liquid into the balloon. Never leave the catheter with the balloon in \202 ated, as pulmonary infarction may occur. CHAPTER 1 Cardiovascular emergencies 64 Table 1.7 Normal values of right heart pressures and \202 ows Right atrial pressure 0 \200\2238 mmHg Right ventricle Systolic 15 \200\22330 mmHg 0 \200\2238 mmHg End diastolic Pulmonary artery Systolic/diastolic 15 \200\22330/4 \200\22312 mmHg 9 \200\22316 mmHg Mean Pulmonary capillary wedge pressure 2 \200\22310 mmHg 2.8 \200\2234.2 L/min/m2 Cardiac index 60 50 40 30 20 10 0 ) g H m m ( Right atrium Right ventricle Pulmonary artery Wedge position (PCWP) Figure 1.10 Pressure tracings during pulmonary artery catheterization. The plastic of the catheter softens with time at body temperature and the tip of the cathet er may migrate further into the PA branch. If the pressure tracing with the balloon de \202 ated is \200\234partially wedged \200\235 (and \202 ushing the catheter does not im prove this), withdraw the catheter 1 \200\2232 cm and reposition. Sometimes it is impossibl e to obtain a wedged trace. In this situation one has to use the PA diastolic pressure as a guide. In health there is 2 \200\2234 mmHg difference between PA diastolic pressure and P CWP. Any condition that causes pulmonary hypertension (e.g., severe lung disease, ARDS, lon g-standing valvular disease) will alter this relationship. Valvular lesions, VSDs, prosthet ic valves, and pacemakers present seek advice from a cardiologist. The risk of subacute bac terial endocarditis (SBE) may be suf \201 ciently great that the placement of a PA cathete r may be more detrimental than bene \201 cial. Positive end-expiratory pressure (PEEP): Me asurement and interpretation if PCWP in patients on PEEP depends on the position of the cat heter. Ensure that the catheter is below the level of the left atrium on lateral CXR. Remov ing PEEP during measurement causes marked \202 uctuations in hemodynamics and oxygenation , and the pressures do not re \202 ect the state once back on the ventilator. : If these are PULMONARY ARTERY CATHETERIZATION 65 Complications Arrhythmias Watch the ECG tracing closely while the catheter is advanced. The cath- eter commonly triggers runs of VT when crossing the tricuspid valve and through the RV. If this happens, de \202 ate the balloon, pull back, and try again. The VT is usually self-limiting, but should not be ignored. Pulmonary artery rupture Occurrence of PA rupture was 0.2% in one series. Damage may occur if the balloon is overin \202 ated in a small branch. Risk factors include mitral valve disease (large v wave confused with poor wedging), pulmon ary hypertension, and multiple in \202 ations or hyper- in \202 ations of balloon. Hemopt ysis is an early sign. It is safer to follow PA diastolic pressures if these correlate with the PCWP. Pulmonary infarction Knots These usually occur at the time of initial placement in patients where there has been dif \201 culty in traversing the RV. Signs include loss of pressure tra- cing, persistent ectopy, and resistance to catheter manipulation. If this is suspected , stop manipulation and seek expert help. Infection Risks increase with length of time the catheter is left in situ. Pressure trans- ducer may occasionally be a source of infection, so keep in place for the shortest possible time. Remove the catheter and introducer and replace only if necessary. Other complications Other complications are those associated with central line insertion, t hrombosis and embolism, balloon rupture, and intracardiac damage. CHAPTER 1 Cardiovascular emergencies 66 Indications for temporary pacing 1. Following acute myocardial infarction \200 \200 \200 \200 Asystole Symptomatic complete heart block (CHB) (any territory) Symptomatic secondary heart block (any territory) Trifascicular block (currently often managed with Zoll de \201 bril lator) \200 \200 \200 \200 After anterior MI \200 \200 Symptomatic sinus bradyc ardia unresponsive to atropine Recurrent VT for atrial or ventricular overdrive pacing Alternating LBBB and RBBB First-degree AV block + RBBB + LAD New RBBB and left posterior he miblock LBBB and long PR interval Asymptomatic CHB Asymptomatic second-degree (Mobitz II) block \200 2. Unrelated to myocardial infarction \200 Symptomatic sinus or junctional bradycardia unresponsive to atropine (e.g., carotid sinus h ypersensitivity) Symptomatic second-degree heart block or sinus arrest Symptomatic CHB Tors ades de pointes tachycardia due to bradycardia Recurrent VT for atrial or ventricular overd rive pacing Bradycardia-dependent tachycardia Drug overdose (e.g., verapamil, Permanent pac emaker box change in a pacing-dependent patient (not usually done) \200 \200 \200 \200 \200 \200 B-blockers, digoxin) 3. Before general anesthesia \200 \200 Use the same principles as for acute MI Sinus node disease and second-degree (Wenckebach) h eart block need prophylactic pacing only if there are symptoms of syncope or presyncope. CH B. Transvenous temporary pacing The technique of temporary wire insertion is described on p. 6 8. The most commonly used pacing mode and the mode of choice for life-threatening bradyarrhyth mias is ventricular demand pacing (VVI) with a single bipolar wire positioned in the right ventricle. In critically ill patients with impaired cardiac pump function and symp- tomatic bradycardi a (especially with right ventricular infarction), cardiac output may be increased by up to 20% by maintaining atrioventricular (AV) synchrony. This requires two pacing leads, one atr ial and one ventricular, and a dual pacing box. Indications for temporary transvenous cardiac pacing are listed in Table 1.8. INDICATIONS FOR TEMPORARY PACING 67 Epicardial temporary pacing Following cardiac surgery, patients may have epicardial wires ( attached to the pericardial surface of the heart) left in for up to 1 week in case of posto perative bradyarrhythmia. These are used in the same way as trans- venous pacing wires, but the threshold may be higher. They are removed prior to discharge. Table 1.8 Indications for temporary transvenous cardiac pacing Emergency/acute Acute myocardial infarction (class I: ACC/AHA)* \200 \200 Asystole Symptomatic bradycardia (sinus bradycardia with hypotension and type I second-degr ee AV block with hypotension not responsive to atropine) Bilateral bundle branch block (alt ernating BBB or RBBB with alternating LAHB/LPHB) New or indeterminate age bifascicular bloc k with \201 rst-degree AV block Mobitz type II second-degree AV block \200 Bradycardia not associated with acute myocardial infarction \200 \200 Asystole Second- or third-degree AV block with hemodynamic compromise or syncope at rest Ve ntricular tachyarrhythmias secondary to bradycardia Elective \200 \200 Support for procedures that may promote bradycardia General anesthesia with: \200 \200 \200 \200 Second- or third-degree AV block Intermittent AV block First degree AV block with bifascicu lar block First degree AV block and LBBB Cardiac surgery (not usual) \200 \200 Aortic surgery Tricuspid surgery Ventricular septal defect closure Ostium primum repair \200 Rarely considered for coronary angioplasty (usually to right coronary artery) Overdrive suppression of tachyarrhythmias Ryan TJ, et al. (1996). ACC/AHA guidelines for the management of patients with acute myocar dial infarction. J Am Coll Cardiol 28:1328 \200\2231428. Reproduced with permission from Ga mmage MD (2000). Temporary cardiac pacing. Heart 83:715 \200\223720. CHAPTER 1 Cardiovascular emergencies 68 Temporary ventricular pacing For a checklist for inserting a pacing wire, see Box 1.12. \200 Cannulate a central vein: right interior jugular (RIJ) approach but is more comfortable for the patient via the right subclavian (SC) vein. The LIJ approach is best avoided as there are many acute bends to negotiate and a stable position is dif \201 cult to achieve. Avoid the left subclavicular area as this is the preferred area for permanent pacemaker insertio n and should be kept \200\234virgin \200\235 if possible. The femoral vein may be used (in cidence of DVT and infection is high). Insert a sheath (similar to that for PA catheterizat ion) through which the pacing wire can be fed. Pacing wires are commonly 5F or 6F and a she ath at least one size larger is necessary. Most commercially available pacing wires are pre packed with an introducer needle and plastic cannula similar to an Abbocath , which may be used to position the pacing wire. However, the cannula does not have a hemostatic seal. Th e plastic cannula may be removed from the vein, leaving the bare wire entering the skin, on ce a stable position has been achieved. This reduces the risk of wire displacement but also makes repositioning of the wire more dif \201 cult should this be necessary, and infectio n risk is higher. Pass the wire the introducer sheath and advance into the upper right atri um (see Fig. 1.11) but do not unfurl the cover yet. The wire is much easier to manipulate w ith gloved hands without the hindrance of the plastic cover. Advance the wire may cross the tricuspid valve easily. If it fails to cross, point the tip to the lateral wall of the atr ium and form a loop. Rotate the wire and the loop should fall across the tricuspid valve in to the ventricle. The wire is easiest to manipulate via the through the sterile plastic cover that accompanies with the tip pointing toward the right ventricle; it Advance and rotate the wire so that the tip points inferiorly as close to the apex of the r ight ventricle (laterally) as possible. Box 1.12 Checklist for pacing wire insertion \200 Check that the \202 uoroscopy and monitoring equipment and de \201 brillator are working . Check the type of pacing wire: atrial wires have a preformed \200\234J \200\235 that all ows easy placement in the atrium or appendage and are very dif \201 cult to manipulate int o a satisfactory position in the ventricle. Ventricular pacing wires have a more open, gent le \200\234J. \200\235 Check the pacing box (single vs. dual or sequential pacing box) and leads to attach to the wire(s). Familiarize yourself with the controls on the box; you may need to connect up in a hurry if the patient \200\231s intrinsic rhythm slows further. Rem ember to put on the lead apron before wearing the sterile gown, mask, and gloves. TEMPORARY VENTRICULAR PACING 69 SVC Pulmonary artery RV Tricuspid valve IVC Figure 1.11 Insertion of a ventricular pacing wire (see text for details). Reproduced with permission from Ramrakha P, Moore K (2004). Oxford Handbook of Acute Medicine, 2nd ed. Oxfo rd, UK: Oxford University Press. If the wire does not rotate down to the apex easily, it may be because you are in the coron ary sinus rather than in the right ventricle. (The tip of the wire points to the left shoul der). \200 Withdraw the wire in the wire; the \201 nal appearance should be like the outline of a so ck with the \200\234heel \200\235 in the right atrium, the \200\234arch \200\235 over the tricuspid valve and the \200\234big toe \200\235 at the tip of the right ventricle. Conne ct the wire Ventricular pacing thresholds should be <1.0 V, but threshold up to 1.5 V is ac ceptable if another stable position cannot be achieved. Check for positional stability. tha n the intrinsic heart rate, ask the patient to take some deep breaths, cough forcefully, an d sniff. Watch for failure of capture; if this happens, reposition the wire. and re-cross the tricuspid valve. Leave some slack to the pacing box and check the threshold. With the box pacing at a rate higher CHAPTER 1 Cardiovascular emergencies 70 to 5 V and the box on \200\234demand. \200\235 If the patient is in Set the output sinus r hythm and has an adequate blood pressure, set the box rate to just below the patient \200 \231s rate. If there is complete heart block or bradycardia, set the rate at 70 \200\22380/ min. Dress sterilely. sheath and wire securely to the skin. Loop the rest of the wire and \201 x to the patient \200\231s skin with adhesive dressing. When the patient returns to t he ward, obtain a CXR to con \201 rm satisfactory positioning of the wire and to exclude a pneumothorax. Cover the wire with the plastic sheath and suture Temporary pacemaker placement can be done with ECG guidance (clip lead V1 to end of pacing wire) but \202 uoroscopy guidance is preferred. If it is anticipated that a temporary pacer will be needed for more than a short period of time (infected or hemodynamically unstable patient), a permanent screw-in pacemaker lead ma y be placed, externalized, and connected to a nonsterile permanent pacemaker generator whic h is then secured to the patient \200\231s skin. This is especially useful if \200\234temp orary \200\235 atrial or dual chamber pacing is needed. TEMPORARY ATRIAL PACING 71 Temporary atrial pacing The technique of inserting an atrial temporary wire is similar to t hat of ventricular pacing. \200 \200 Advance the atrial wire until the \200\234J \200\235 is re-formed in the right atrium. Rot ate the wire and withdraw slightly to position the tip in the right atrial appendage. Aim f or a threshold of <1.5 V. If atrial wires are not available, a ventricular pacing wire may be manipu- lated into a si milar position or passed into the coronary sinus for left atrial pacing. Alternatively, a s crew-in permanent lead may be used as described on p. 398. CHAPTER 1 Cardiovascular emergencies 72 AV sequential pacing In critically ill patients with impaired cardiac pump function and sym p- tomatic bradycardia (especially with right ventricular infarction), cardiac output may b e increased by up to 20% by maintaining atrioventricular syn- chrony. This requires two pac ing leads, one atrial and one ventricular, and a dual pacing box. Patients most likely to bene \201 t from AV sequential pacing \200 \200 Acute MI (especially RV infarction) \200\234Stiff \200\235 left ventricle: aortic stenosis , hypertrophic cardiomyopathy (HCM), hypertensive heart disease, amyloidosis Low cardiac ou tput states (cardiomyopathy) Recurrent atrial arrhythmias \200 TEMPORARY PACING: COMPLICATIONS 73 Temporary pacing: complications 1. Ventricular ectopy or tachycardia Nonsustained ventricular tachycardia (VT) is common as the guide or pacing wire crosses the tricuspid valve (especially in patients receiving a c atecholamine infusion) and does not require treatment.