Heart and Pulmonary Vasculature

Techniques and Applications

Echocardiography

Includes M-mode, real-time 2D, colour Doppler. Transthoracic or transoesophageal (LA closest to probe).

  • IV septum thickens and moves towards contracting posterior wall of LV during systole. Paradoxic septal motion in pericardial effusion with tamponade, COPD, asthma, ASD, PAH, LBBB and septal ischaemia. Normally <10-11mm at end-diastole.
  • Aortic root lies between RV and LA. 20-40mm (8-12mm in neonates), walls move anteriorly with systole. Dilated in AS, AI, TOF, aneurysm. Cusps should be widely open at systole, should not reverberate.
  • LA is posterior to aortic root. </= 40mm during diastole, should be free of internal echoes.
  • LV is inferolateral to LA. Echo-free apart from thin chordae tendinae and papillary muscles. Transverse diameter </= 57mm at diastole. Posterior wall thickens and moves anteriorly with systole. Wall thickness should be symmetrical and similar to IV septum (10-11mm).
  • Mitral valve has saw-toothed/M-shaped pattern on M-mode, most dominant echo is anterior leaflet with posterior leaflet being W-shaped.
    • A point (second peak) – Atrial contraction
    • B point – notch Between A and C points from LV end-diastolic pressure
    • C point (start of baseline) – Closure of mitral valve with LV contraction
    • D point (end of baseline) – Early Diastole when mitral valve starts to open
    • E point (first peak) – Maximal Excursion of valve opening
    • F point (drop between peaks) – transient drop of valve during early diastolic Filling prior to atrial contraction. The E-F slope is a function of LA emptying rate, should be steep. Is thickened, flattened and squared with mitral stenosis.
  • Tricuspid valve – M-shaped pattern similar to mitral valve.
  • Pulmonary valve – Difficult to image. Diameter similar to aortic root.

Hypokinesia is reduced contractility/systolic motion than normal. Akinesia is no systolic wall motion. Dyskinesia is paradoxical wall motion in systole. Tardikinesia is delayed contraction. Asynchrony is cardiac motion out of phase with rest of myocardium.

Stress echocardiogrpahy after exercise or pharmacologic stress compared with rest to detect new segmental wall motion abnormality or worsening of resting abnormality. Failure of ejection fraction to increased by at least 5% indicates myocardial dysfunction.

Cardiac CT

CT coronary angiography requires slow heart rate of max 60-70bpm, using oral or IV beta blockers. Arms up, single breath-hold, prospective or retrospective ECG gating. Timing performed off a test bolus injection, with optimal imaging at peak opacification of LV and coronary arteries; less opacification of RV and pulmonary aa. Images can be post-processed for 3D reconstructions, MIPS, multiplanar views, MIPS, coronary straightening views.

Cardiovascular MRI (CMR)

Indications CHD, aortic/pulmonary artery diseae, pericardial disease, ventricular function, valvular function, cardiomyopathies, cardiac masses. Best anatomy from T1WI with black blood. ECG gating to provide cine MRI with accurate measurements at points of the cycle, usually done with steady-state free precession (SSFP) or GRE where there is white blood (flow-independent). Planes to match cardiac axis (eg long axis 4-chamber, short axis) or vascular anatomy. Tissue characteristics (for neoplastic, infiltrative of inflammatory myocardial disease) with T1WI, T2WI, enhancement and spectroscopy. Turbulent flow through stenoses or regurgitant valves cause wedge-shaped puff of low signal on GRE; grading of stenosis/incompetence can evaluate the distance, areas or volume of this jet. Velocity-encoded phase-contrast cine-MR can evaluate flow velocities, flow volumes and regurgitant volumes. Area ejection fractions calculated from end diastolic and end systolic areas of the LV. Wall thickening with systole should be at least 2mm.

Techniques include:

  • Ventricular measurements done using stacked short axis SSFP with automated border detection software; more difficult with the RV due to more complex structure and trabeculations. Stroke volume (SV) = EDV-ESV. Ejection fraction (EF) = SV/EDV.
  • Myocardial tagging uses the magnetic field to mark the myocardium; for analysis of normal rotational and translational deformation, and detect areas of abnormallly reduced deformation. A grid of orthoganal saturation pulses applied during end-diastole, ’embedding’ into the tissue. This strain analysis is more accurate than planar wall thickening for dysfunction. May be used with stress imaging to predict functional improvement of reperfusion.
  • Stress imaging usually performed with dobutamine (DCMR), increasing myocardial oxygen demand (chronotropic and ionotropic). Dobutamine is more accurate than adenosine for functional stress testing. Areas of poor reserve develop ischaemia with segmental wall motion abnormality (eg less myocardial thickening). This can be reviewed over differing doses of dobutamine infusions. Suboptimal image quality may be improved with contrast causing LV cavity opacification (LVO). DCMR is more reproducable than dobutamine stress echo (DSE).
  • Myocardial perfusion utilises gadolinium T1WI. First pass imaging (MRFP) done with breath-hold ECG gating during contrast injection with short-axis imaging of transit through the heart from R heart -> L heart -> myocardium (when contrast reaches ascending aorta, peak enhancement at ~10 heartbeats). Time-intensity curves can be generated. Contrast rapidly distributes into extracellular space, hence can only analyse initial upslope. Dobutamine or adenosine given, with upslope used to calculate myocardial perfusion reserve index. Perfusion across layers of the myocardium can be discriminated and subendocardial abnormality can be detected (cf lower resolution PET, SPECT).
  • Myocardial viability means potential benefit (improved contractile function) with revascularisation, whereas nonviability suggests irreversible cell death and worsened outcomes with treatment.
    • Contractile reserve – Low dose DCMR with wall thickening between systole and end-diastole used as a marker of viability. This is able to predict improvement with revascularistion with 90% accuracy. However, areas of myocardial dysfunction consist of reversible (hibernating or stunned myocardium) and irreversible (infarcted) injured myocardium.
    • Infarct imaging – Late contrast enhanced CMR (ce-CMR) at ~10min using Gd-DTPA (Magnevist, extracellular/intersitital contrast agent). Infarct/scarring retains contrast due to increased volume of distribution and delayed washout. This does not occur in areas of reversible injury (hibernating or stunned myocardium). ce-MRI is more sensitive for scar tissue than SPECT or PET due to resolution, being able to detect areas of subendocardial infarction. Extent of transmural hyperenhancement inversely correlates with improvement following revascularisation, even in regions of akinesis/dyskinesis. However, in presence of 1-74% transmural hyperenhancement, DCMR is more accurate in detecting improvement. Areas of hypoenhancement within the hyperenhanced zones represent microvascular obstruction and truly nonviable tissue, increases with infarct size and is a more accurate predictor of prognosis than EF or infarct size.
  • Coronary MRA (CMRA) – Compensation for motion from short acquisition times and ECG gating to middiastole (least cardiac motion). Breath-hold techniques have less signal-to-noise; longer techniques include use of diaphragmatic navigators tracking the lung-diaphragm interface with acquisition of images in a certain position. Best done with a high-fied 3T scanner. Currently CMRA used for anomalous coronary arteries, Kawasaki disease, aneurysms and graft patency. Black-blood imaging allows assessment of the coronary wall.
  • Atherosclerotic plaque imaging – High T2 corresponds to fibre (collagen, elastin, proteoglycans); dark T2 to lipid-rich regions. Fibrous caps are uniform increased T2 with enhancement. Fibrous cap thickness may correlate with stability with thinner caps more prone to rupture. May be used for aortic or carotid atherosclerosis.

Cardiac Nuclear Imaging

See Cardiovascular Scintigraphy

Coronary Angiography

Indications include unstable angina or angina refractory to Rx, high-risk lesions, abnormal exercise tolerance test or stress perfusion tests, occupational risk (eg pilot), preop evaluation, evaluation of bypass grafts or interventional therapy. RAO profiles the interventricular loop (LAD, PDA) with the atrioventricular grooves (LCA, circumflex, RCA) superimposed. The LAO projection profiles the atrioventricular circle, superimposing the interventricular loop. The L anterior craniad view elongades the LCA, LAD and ramus intermedius. Complications include puncture site (haematoma, pseudoaneurysm, fistula), arrythmia (including premature beats), heart block, asystole, MI, stroke, emboli. Catheter spasms most common in RCA as smooth transient narrowing 1-2mm distal to the catheter tip, usually asymptomatic.

Cardiac Silhouette

Cardiothoracic ratio </=0.5 PA or </=0.6 on AP or portable.

Cardiac shape:

  • ‘Water bottle’ shape – Pericardial effusion or general cardiomyopathy
  • LV or ‘Shmoo’ heart – Lengthening and rounding of L border with downward apex from LV enlargement.
  • LV hypertrophy – Increased convexity of L border and apex.
  • RV hypertrophy – Causes lifting of apex, boot-shaped heart.
  • Straightening of the L border – Rheumatic heart disease and mitral stenosis.
  • ‘Skiing moguls’ of the left border – Aortic knob (prominent in ectasia, aneurysm, HTN; notching/’figure-3′ in coarctation), main PA (increased covexity in poststenotic dilatation, COPD, PAH, L>R shunt, pericardial defect; concavity in R>L shunt) and left atrial appendage (90% from previous rheumatic heart disease), just above cardiophrenic angle (indicating infarction or ventricular aneurysm), and at the cardiophrenic angle (indicates pericardial cyst, prominent fat pads or adenopathy).

Chamber enlargement:

  • LA – Distance from mid inferior L main bronchus to R lateral border LA >70mm with double heart border, splaying of carina >90deg, L main bronchus displaced superior and posterior (walking man sign on lateral XR), prominent LA appendage, displacement of descending aorta to L, ‘atrial escape’ (massive enlargement with LA forming R heart border). On CT any dimension >40mm.
  • RA – Atrial bulge >55mm from midline, elongation of RA convexity >50% of border. On CT axial long axis >54mm.
  • LV – Elongated L border with apex pointing down, prominent rounding of inferior L border, LV extending posterior to oesopahgus (on lat), (Hoffman-)Rigler sign (LV >18mm posterior to posterior border IVC at level 20mm superior to intersection of LV and IVC; requires true lat).
  • RV – Cardiomegaly with negative Hoffman-Rigler sign, filling of retrosternal clear space or ascends >1/3 of sternal length.
  • IVC >22mm

Ascending aortic dilatation DDx – Poststenotic dilatation from aortic valve stenosis, systemic HTN (associated with tortuosity of entire aorta), aneurysm (syphilis causes calcification, Marfan no calcification).

Azygos vein dilation (>6mm erect, >10mm supine) – Volume overload, elevated venous pressure, RH failure, Valsalva maneuver, pregnancy, renal failure, vena cava obstruction, azygos continuation of the IVC.

Calcifications:

  • Coronary artery – In CAC triangle.
  • Valves
  • Sinus of Valsalva aneurysm
  • Ligamentum arteriosum – In AP window from LPA to floor of arch.
  • LA wall – Associated with mitral stenosis, LA enlargement, AF, LA thrombus.
  • Pericardium – Usually anterior and inferior, single or double-layered. From virus, haemorrhage, TB, postsurgical scarring. High risk of contstrictive pericarditis.
  • Infarct – Dystrophic calcification in myocardial wall from MI.
  • Ventricular aneursym – Anterolateral near apex in true aneuryms, posterior in pseudoaneurysm.
  • Thrombus – In LA, less common in LV.
  • PAs – Thin, egg-shell from chronic PAH.
  • Tumour – Rounded, stippled in atrial myxoma.

Paediatric Heart Disease

See Paediatric Heart Disease

Ischaemic Heart Disease (IHD)

90% from coronary obstructive atherosclerosis. Other causes include emboli, occlusion of small myocardial vessels, shock. Aggrevated by increased energy demand (hypertrophy, tachycardia), hypoxaemia, anaemia, shock.

Coronary Artery Disease (CAD)

Most common cause of mortality. Coronary arteries are narrowed/occluded by atherosclerosis, thrombus, intraluminal ulceration and haemorrhage, vasoconstriction or coronary actesia and aneurysm. Increased risk with high cholesterol and CRP, smoking, diabetes, HTN, sedentary lifestyle, obesity, age, male, chronic inflammation, FHx. Clinical syndromes include:

  • Angina pectoris (chest pain) – Ischaemia insufficient to cause infarction.
    • Stable/typical angina – Precipitated by exercise, releived by rest or GTN. Requires >75% luminal obstruction, when compensatory vasodilatation is no longer sufficient, usually not associated with plaque disruption.
    • Prinzmetal angina – Prolonged spasm, usually unrelated to activity, HR or BP. Provocative test using IV ergonovine to incite spasm and Sx. Tx medical.
    • Unstable/crescendo/preinfarction angina – Lower levels of activity or at rest. Requires >90% luminal obstruction, usually associated with plaque disruption and partial occlusion. Imminent acute MI.
  • Myocardial infarctiom (MI) – Death of heart muscle from complete occlusion.
  • Sudden cardiac death (SCD) – Unexpected death from cardiac cause with preceding symptoms <1hr. 90% from ischaemia (not MI) inducing myocardia irritability and fatal ventricular arrthmia. Other causes include congenital abnormalities, AS, MI, myocarditis, dilated/hypertrophic cardiomyopathy, PAH, cardiac arrhythmias, hypertrophy, systemic metabolic/haemodynamic alteration, catecholamines, drugs (cocaine, methamphetamine).
  • Chronic IHD with heart failure

Plaque formed by lipoprotein deposition into vessel walls with overlying fibrous cap. Mechanical stress may cause plaque disruption/change (rupture, superficial erosion, ulceration, fissuring or deep haemorrhage), usually leading to occlusive thrombus, acute coronary syndrome (unstable angina, acute MI, sudden death).

Calcification occurs in the intima. Coronary artery calcification (CAC) triangle is 30mm along upper L heart border. CAC + chest pain has 95% chance of occlusive coronary disease, esp <60yo. Coronary artery calcium scoring using Agatston method defines calcifcation as >130HU over >2mm2. In asymptomatic patients CAC has predictive accuracy of 86%. Score 1 for 130-200HU; 2 for 201-299HU; 3 for 300-399HU; 4 for >/= 400HU. Score is multiplied against area of the lesion for each coronary artery territories (LM, LAD, LCx, RCA). Total Agatston score of 0-10 low risk; 11-100 moderate risk; 101-400 moderate risk; >400 high risk for underlying stenosis and future cardiac events. The specific calcified area or artery may not correlate with the actual stenosis. Absence of calcification essentially excludes significant underlying stenosis.

75% reduction in cross-sectional area (50% stenosis/reduction in diameter) is required to cause significant reduction in blood flow. 75% stenosis is high grade. Collateral flow develops after 85% stenosis. Grading of stenosis using CT is difficult when heavy calcification or stents are present. Degree of disease asessesed by percent stenosis of each coronary arteries or number of 5mm segments of arteries involved (RCA is 100mm, LM 10mm, LAD 100mm, LCx 60mm for total of 270mm). Scoring of degree into 0-25%, 25-50%, 50-75% or 75-100%. Stenoses usually within 1st several cm. Atherosclerosis of the intramural/penetrating branches is rare. Ischaemia reduces intraluminal pressure, stimulating enlargement of collateral vessels including epicardial, intramyocardial, atrioventricular, intercoronary or intracoronary (bridging collateral) vessels.

Treatment:

  • Percutaneous transluminal angioplasty (PTCA) – 85-90% initial success, but restenosis in up to 50% within 1st 6/12. Multivessel PCTA similar reduction of death/MI as bypass, but requires more repeat follo-up procedures.
  • Coronary bypass – Saphenous vein grafts or native IMA. Shown to prolong life in LCA or 3-vessel disease. Usually reserved for more complex or longer segment disease.

Other coronary artery diseases:

  • Kawasaki syndrome – ?Previous viral infection causing inflammation, stenosis and aneurysms of coronary arteries. Occasional persistence into adulthood.
  • Myocardial bridging – Normal variant. Coronary a penetrates then emerges from the myocardium causing constrictions during systole.

Myocardial Infarction (MI)

Most infarcts are thought to be due rupture of the fibrous cap of atheromas inducing thrombosis or haemorrhage into the plaque; thus occluding the lumen. Most of these plaques are initially only causing mild or moderate stenoses, hence previously asymptomatic. LAD in 40-50% (anterior LV, anterior 2/3 septum, apex), RCA in 30-40% (inferoposterior LV, posterior septum, inferior and posterior RV free wall), LCx in 15-20% (lateral wall LV except apex). 10% have no typical coronary pathology; may be reduced coronary flow from vasospasm (platelet aggregation, cocaine), emboli (from LA in AF, mural thrombus, infective endocarditis, prosthetic material, paradoxical), vasculitis, sickle cell disease, amyloid deposition, dissection, shock, inadequate myocardial protection during cardiac surgery. Early reversible changes (seconds-minutes) include cessation of aerobic metabolism, accumulation of lactic acid, loss of contractility (within 2min, may cause acute heart failure), reduction in ATP. Irreversible damage (necrosis) of myocytes occurs after 20-30min of severe ischaemia, with leak of intracellular macromolecules, then injury to microvasculature. In most cases permanent damage occurs after 2-4hours. The nonperfused area is the ‘at risk’ myocardium. <12hrs there is no gross abnormality, 12-24hrs dark mottling (trapped blood), then yellow-tan, 10-14/7 hyperaemic border (vascularised granulation tissue), over weeks depressed with evolving white scar. Larger infarcts heal slower due to lack of inflammatory cells reaching reaching the region.

Most infarcts are transmural, result in STEMI. Subendocardial (nontrasmural infarct) is limited to the inner 1/3-1/2 of ventricular wall (least perfused and most vulerable), from coronary occlusion that becomes lysed before transmural infarct, or shock superimposed on chronic coronary stenoses; usually circumferential (rather than single vessel distribution), results in NSTEMI. A narrow rim (~0.1mm) of subendocardial myocardium is always preserved due to diffusion from the ventricular lumen.

Image in cases of late presentation, equivocal enzymes/ECG, recent cardiac surgery/trauma or suspected RV infarct.

  • See Cardiovascular Scintigraphy
  • Cardiac CT – Poor enhancement of infarcted segment with delayed (10-15min) peripheral enhancement.
  • Cardiac MR – Myocardial oedema with high T2 low T1 within 1hr of infarct, may be associated with some haemorrhage. Surrounding oedema overestimates the size of the infarct. Gad shows nonenhancement. Regional wall thinning, lack of systolic thickening. Cannot be distinguisehd from hibernating myocardium.
  • Echocardiography – Hypokinesis, akinesis or dyskinesis, unable to be distinguished from stunned or hibernating myocardium. Thin hyperechoic walls with motion abnormality suggets transmural scar. Microbubble contrast will show non-enhancement.

Poorer prognosis with age, females, diabetes, previous MI (cumulative loss of functional myocardium). Complications include:

  • Contractile dysfunction causing cardiogenic shock – Systolic pressure <90mmHg.
  • Arrhythmia – Myocardial irritability and/or conduction defects. Atrioventricular block – esp inferior infarcts with ischaemia/injury to AV nodal branch of RCA.
  • RV infarction – In 33% of inferior wall infarcts (rare isolated). Acute RVF.
  • Myocardial rupture – 3-10 days posterior MI with mortality approaching 100%. Weakening of the necrotic inflammed myocardium.
    • Myocardial free wall (most) – Esp anterolateral wall at the midventricular level. Acute cardiac enlargement with haemopericardium. Higher risk with >60yo, females, pre-existing HTN. If there is a pericardial adhesion may be contained in a false aneurysm.
    • Rupture of the IV septum – Usually from anterior/LAD infarct. Acute VSD with L>R shunt and acute increase in RV pressure, pulmonary vascular engorgement, RH enlargement, usually no pulmonary oedema. Mortality 25% at 24hrs, 90% at 1yr.
    • Papillary muscle rupture – Abrupt mitral regurgitation with acute pulmonary oedema, enlarged LA. Usually inferior infarcts, less commonly anterior. Mortality 70% at 24hrs, 90% at 1yr. Papillary muscle dysfunction may also occur from ischaemic dysfunction, fibrosis and shortening or ventricular dilatation.
  • Dressler syndrome (postmyocardial infarction syndrome) – Fibrinous or fibrohaemorrhagic pericarditis after a transmural infarct, from myocardial inflammation. Probably autoimmune several weeks after MI with fever, CP, pericarditis, pericardial effusion, pleuritis with pleural effusion L>R.
  • Infarct extension – From retrograde propagation of the thrombus, proximal vasospasm, progressively impaired contractility (reducing flow through stenoses), microemboli or arrhythmias.
  • Infarct expansion – Weakened necrotic muscle causes disproportionate stretching, thinning and dilatation, ± mural thrombus. Esp anteroseptal infarcts.
  • True ventricular aneurysm – Bulge in ventricular wall moving paradoxically. Lined my thinned scarred myocardium (delayed enhancement), usually at apex or anterolateral wall (LAD disease), broad-based. Late complication of large transmural infarcts that have early expansion. Commonly calcifies. May also be from Chagas disesae, trauma, rarely congenital. Increased risk of mural thrombus (50%), arrhythmias, HF. Rupture does not occur due to tough fibrotic wall.
  • Mural thrombus – Localised noncontractile myocardium (stasis), endocardial damage (thrombogenic surface).
  • Chronic IHD (ischaemic cardiomyopathy) – Progressive heart failure, most have had prior MI. Functional decompensation of hypertrophied noninfarcted myocardium. Develops in 60-70% of those with MI, esp anterior wall infarct, multivessel, LV aneurysm.

Reperfusion performed by thrombolysis, angioplasty ± stent or coronary artery bypass graft (CABG). The earlier the better the results (esp <3-4hrs), after 20min areas of permanent necrosis progress from subendocardium to subepicardium over time (‘time is muscle’). Infarct usually becomes haemorrhagic, may induce arrhythmias, microvascular injury. Contraction bands occur in dead myocardial cells exposed to plasma calcium (intracellular eosinophilic stripes from exaggerated myofibril contraction). Reperfusion injury – irreversible cell damage superimposed on ischaemic injury, from oxidative stress, calcium overload and/or inflammation.

  • Stunned myocardium – Reversible biochemical abnormality of myocytes rescued from ischaemia by reperfusion. Abnormal wall motion that tends to normalise with inotropes, normal perfusion and metabolism. Usually recovers after several days.
  • Hibernating myocardium – Chronic sublethal ischaemia induces lower state of metabolism and function. Abnormal wall motion which normalises after nitrates, inotropes, PTCA or CABG. Adequate perfusion and metabolism to survive.

Cardiomyopathy

8:100,000, M>F, blacks > whites. From failure to maintain structure, electrical activity or cardiac output. Cardiomegaly, CHF, raised end-diastolic pressures, reduced contractility, reduced EF. Hyperenhancement on ce-MRI from ischaemia, active myocarditis (esp lateral free wall) or chronic/healed myocarditis (only mid-wall hyperenhancement). Lack of hyperenhancement means non-ischaemic aetiology. Primary cardiomyopathies predominantly affect mycoardium; secondary are part of a systemic/multiorgan disorder.

Dilated Cardiomyopathy (DCM, 90%)

From ischaemia (most common), myocarditis (esp Coxsackie virus, enteroviruses), toxins (alcohol, doxorubicin), childbirth (peripartum cardiomyopathy), genetic (20-50% including MPS, glycogen storage diseases, haemochromatosis). Congestive cardiomyopathy when aetiology is unknown. Impaired contractility (systolic dysfunction) with LVEF <40% (normal 50-65%). May be R-dominant, L-dominant or biventricular. Dilated LV and LA, global hypokinesia, thinning of ventricular walls. Mural thrombi common.

Arrhthmogenic RV dysplasia/cardiomyopathy (ARVD/ARVC) – Similar/?same as Uhl anomaly. Form of DCM. Inherited AD, M>F, young. Loss of RV myocytes with extensive fatty infiltration and fibrosis. Dilated or aneurysm of RV with marked thining of free wall and fatty infiltration on MR (also seen in other RV arrhythmias), occasionally also of LV. Naxos syndrome is ARVD, woolly hair and hyperkeratosis of plantar and palmar skin surfaces.

Hypertrophic Cardiomyopathy (HCM)

Familial AD in 60%, associated with NF, Noonan syndrome. Unkown aetiology. Impairment of compliance (diastolic dysfunction) within muscular outflow causing intermittent obstruction during systole. Usually asymmetrical septal hypertrophy esp basal septum (ASH, HOCM, idiopathic hypertrophic subaortic stenosis IHSS); rarely concentric hypertrophy (diffuse, midventricular or apical). Systemic HTN may cause LV hypertrophy then dilatation. Sudden death in 50%. 50% have normal CXR, 30% LA enlargement due to mitral regurgitation. Hypertrophy of IV septum (>12-13mm), more than posterior wall (>1.3:1), anterior motion of mitral valve causing regurgitation, narrowed LVOT during systole with high velocity and delayed systolic peak, midsystolic closure of aortic valve, normal or hyperkinetic LV, increased LVEF. LV size is normal to small. Patchy fibrous/scar tissue within thickened myocardium, with enhancement on late ce-MRI. Progressive disease -> wall thinning, cavitation. Heterogeneous intramural function on tagged MRI from fibrosis and myofibrillar disarray. DDx sigmoid septum (age-related bulging of the basal IV septum into the LVOT).

Restrictive Cardiomyopathy

Impairment of ventricular compliance (diastolic dysfunction). No cardiomegaly or ventricular hypertrophy. Low voltate ECG. Impaired diastolic function with reduced compliance, poor filling. Systolic function near normal. May have increased pulmonary venous pressure with enlarged RA. Hot spots on Tc-99m-PYP scan. Normal to small EF. Mild LV wall hypertrophy with granular/snowstorm appearance to myocardium (esp amyloidosis) and high T2. From infiltrative disease including:

  • Idiopathic
  • Endomyocardial fibrosis – Children and young adults in Africa and tropics. Fibrosis of ventricular endocardium and subendocaridum extending from apex. Unknown aetiology.
  • Loffler endocardial fibrosis – Associated with eosinophilia. Typically associated with large mural thrombi.
  • Amyloid – Concentric hypertrophy (incl RV free wall), biatrial dilatation and hypertrophy, valvular thickening, reduced systolic function. Diffuse subendocardial late enhancement is characteristic.
  • Cardiac sarcoidosis – Common with systemic disease, but uncommonly symptomatic. Causes oedema, granuloma then fibrosis. Patchy myocardial enhancement, may regress after high-dose steroids.
  • Glycogen storage disease
  • MPS
  • Haemochromatosis
  • Tumour or metastases

Congestive Heart Failure (CHF)

Heart is unable to pump at a rate sufficient to meet metabolic demands, or can only do so at elevated filling pressures. End-stage of chronic heart disease, or acute haemodynamic stress (volume overload, acute valve dysfunction, large MI). There is dilatation (enhancing contractility), ventricular remodelling (myocardial hypertrophy), activation of neurohumoral systems (norepinephrine, renin-angiotensin-aldosderone system RAAS, atrial natriuretic peptide ANP) to maintain cardiac output. Ventricular hypertrophy increases oxygen demand and hence vunerable to decompensation. Causes include:

  • Myocardial – Cardiomyopathy, myocarditis, postpartum cardiomyopathy
  • Coronary – Transient ischaemia, chronic ischaemia, previous infarct, anuerysm
  • Endocardial – Fibrosis, Loffler syndrome
  • Valvular – Stenosis, regurtitation
  • Pericardial – Effusion, constrictive
  • Vascular – HTN, PE, AVF, vasculitis
  • Extracradiac – Endocrinopathy, toxic, anaemic, metabolic

High-outut states include volume overload, pregnancy, peripheral AV shunts, hyperthyroidism, anaemia, leukemia.

Left heart failure is caused usually from ischaemic heart disease, HTN, aortic/mitral valve disease or myocardial disease.

Right heart failure is mostly caused by left heart failure with PAH; pure RVF usually from chronic lung disease (cor pulmonale eg COPD, primary PAH). RV hypertrophy and dilatation, systemic venous dilatation (azygos vein, SVC, jugular veins, IVC, hepatic veins), tricuspid incompetence. Passive congestion of the liver causing congestive hepatomegaly, most prominent around central veins (red-brown, nutmeg liver), may lead to centrilobular necrosis, cardiac sclerosis and cardiac cirrhosis with portal hypertention. Pleural, pericardial and peritoneal effusions. Protects the lungs by accumulating fluid outside the lungs.

Cor pulmonale is secondary to pulmonary parenchymal/vascular disaese. From pulmonary destruction (ILD, COPD), hypoxic vasoconstriction (chronic bronchitis, asthma, CNS hypoxia, upper airways obstruction), PE (acute or chronic), idiopathic PAH, poor chest wall compliance (chest deformities, morbid obesity = pickwikian syndrome, neuromuscular diseases). Acute cor pulmonale causes dilatation without hypertrophy. Chronic cor pulmonary causes RV hypertrophy then dilatation, failure. Normal/mild cardiomegaly, RV/RA enlargement, oligemic lungs, interlobar artery >16mm, reduced RVEF.

Valvular Heart Disease

Velocity-encoded/phase-contrast cine MR utilises phase shifts of protons as they move, with degree of phase shift used to calculate velocity. Velocity maps used in any direction by changing the direction of flow encoding. Bernoulli equation: ΔP = 4V2 to calculate pressure differences across a stenotic orifice. Flow volumes can be calculated with velocities integrated over an area.

Abnormal flow can cause dephasing of spins with signal voids on GRE cine white-blood CMR to grade the regurgitant jet. This effect is less with SSFP cine, and is dependent on other hardware/sequence characteristics. Alternatively a saturation band can be applied above the aorta, with retrograte movement in the ascending or descending aorta to detect severe AR. Regurgitant fraction dependent on stroke volumes (SV) of RV and LV which are normally equal = (RVSV – LVSV)/RVSV; as determined on gated blood pool scintigraphy or velocity-encoded CMR; but inaccurate when there is more than 1 regurgitant valve.

Aortic valve

  • Stenosis – Increased risk in bicuspid valves (1-2% of population, M>F) of which most develop calcification. Calcific/degenerative aortic sclerosis -> stenosis in older patients with HTN, associated with coronary calcification. Heaped-up calcified masses within the cusps, protruding through outflow surfaces into sinuses of Valsalva prevents opening; free edges usually spared. Noncalcific stenosis usually rheumatic heart disease. Normal valve 2.5-3.5cm2, symptomatic when orifice <0.7cm2 (or <1.5cm2 if concomitant insufficiency). Pressure gradient >25mmHg mild, 40-50mmHg moderate, >80mmHg severe. LV hypertrophy with turbulent flow, reduced LVEF. 80% associated with poststenotic dilatation of the ascending aorta. Grade of stenosis correlates with length of signal loss of jet distal to the aortic valve, narrower jets, and acceleration signal void proximal to the valve
  • Insufficiency/regurgitation – Primary (valve disease eg rheumatic heart disease, infective endocarditits) or secondary (aortic root disease eg Marfan syndrome, aneurysm). Water-hammer pulse, decrescendo diastolic murmur. Dilated calcified aortic root (ascending aorta should not be seen on PA CXR <40yo), enlarged LV ± LA. Diastolic flutter of the IV septum or anterior mitral leaflet (Austin Flint phenomenon), increased LVEF. Graded by regurgitant flow width to aortic root width.
  • Supravalvular stenosis – Hourglass narrowing (<20mm) above the valve from fibrous membrane, or hypoplastic ascending aorta. Associated with peripheral pulmonary stenosis, valvular or subvalvular aortic stenosis in Marfan or Williams syndrome. Dilated coronary aa.
  • Subvalvular/subaortic stenosis – Fixed stenosis associated with congenital heart dsiaese (VSD in 50%), may be membrane or fibromuascular. Functional/dynamic stenosis from hypertrophic obstructive cardiomyopathy.

Mitral valve

  • Annular calcification – Deposits in peripheral fibrous ring/annulus, usually not affecting valvular function. Uncommonly may lead to regurgitation, stenosis or arrhythmias. Esp women >60yo with mitral valve prolapse or elevated LV pressure.
  • Stenosis – Usually postinflammatory scarring (rhuematic heart disease) with 50% having history of rhematic fever. F:M 8:1. Orifice normally 4-6cm2. Mild <1.5cm2 with CXR normal. Moderate <1.0cm2 with enlarged LA (straightened LH border), pulmonary veins, SOBOE. Severe <0.5cm2 with markedly enlarged LA, RV, cephalisation, septal lines, oedema, occasionally LA wall calcification, SOBAR. Reduced E-F slope on M-mode echo with thickened valve and reduced excursion. Grading can also be performed by sizing the signal loss of the jet extending into the LV during diastole. Calcification seen on XR in 40%. Risk of AF when LA >50mm, atrial thrombi. Chronic PV HTN -> PAH. Lutembacher syndrome – MS and pre-existing ASD causing marked right heart enlargement.
  • Insufficiency/regurgitation – From mitral valve prolapse (infarct and rupture of the papillary muscle), rheumatic heart disease, congenital heart disease, ruptured chordae tendinae, infectious endocarditis, mitral annulus calcification. Enlarged LA (more than just MS), LV, pulmonary venous HTN (less than MS). Elevated LVEF due to hyperdynamic state. Regurgitant LV -> LA jet on MR, graded mild/mod/severe depending on distance extending to back wall.
  • Prolapse (myxomatous degeneration of the mitral valve, floppy mitral valve, Barlow syndrome) – 2-6% of population esp young women, AD, associated with straight backs, pectus excavatum, narrow chest AP diameter. Honking-type murmur or midsystolic click. Bulging/hooding (hammock type bowing) of anterior/posterior leaflets at mid-systole when they should be closed. Leaflets may become myxomatously thickened. Increased risk of infective endocarditis, MR, stroke, arrythmias.

Pulmonary valve

  • Stenosis – 95% from partial commisural fusion, presenting in childhood/young adult. Pressure gradient >10mmHg, significant if RV pressure >70mmHg (N 25). RV hypertrophy, jet of contrast extending into LPA with poststenotic dilatation. Dysplastic pulmonary stenosis (5%) has immobile, thick and redundant cusps with no poststenotic dilatation.
  • Infundibular/subvalvular stenosis – In ToF or ventricular septal defects. Preferential flow into right lung.
  • Peripheral/supravalvular stenosis – Most associated with valvular stenosis. Narrowing in MPA, bifurcation, lobar or segmental branches. May be associated with Williams syndrome, TOF, Ehlers-Danlos, postrubella syndrome.
  • Insufficiency – Uncommon, usually after bacterial endocarditis.

Infective Endocarditis (IE)

Increased risk with rheumatic heart disease, mitral valve prolapse, AS, AR, bicuspid aortic valves, MS, MR, congenital heart disease (esp VSD, TOF), prosthetic valves, IVDUs (esp tricuspid valve associated with septic pulmonary emboli). From S.aureus, Strep.viridans, Serratia, Pseudomonas, Candida, Aspergillus. Acute IE from necrotizing ulcerative infection, death in days-weeks. Subacute bacterial endocarditis (SBE) organisms are less virulent with insidious infection. Colonization or invasion of heart valves with formation of vegetations. Most commonly aortic and mitral valves; right heart valves in IVDU. Vegetations cause excessive vibration of valves, appear thickened/fuzzy, may cause incompetence of acute valve destruction. Vegetations may remain after treatment.

Noninfected/Sterile Vegetations

  • Nonbacterial thrombotic endocarditis (NBTE, marantic endocarditis) – Deposition of small sterile thrombi along the line of closure. Usually debilitated patients with cancer (esp mucinous adenocarcinoma, Trousseau syndrome) or sepsis, associated with DVT, PE with hypercoagulable state.
  • Libman-Sacks disease (endocarditis of SLE) – Small vegetations of mitral and tricuspid valves, may be on undersurfaces, chords or endocardium of atria or ventricles.
  • Carcinoid heart disease – Systemic carcinoid syndrome involving endocardium and valves or right heart in 1/2. Plaquelike endocardial fibrous thickenings of chambers and tricuspid and pulmoanry valves. May cause TR, pulmonary insufficiency.

Rhematic Heart Disease (RHD)

Rheumatic fever (RF) is acute multisystem inflammation a few weeks after 3% of group A streptococcal pharyngitis esp 5-15yo (rare after other infections), with migratory polyarthritis of large joints, pancarditis, subcutaneous nodules, erythema marginatum and Sydenham chorea. Lesions on valves (Aschoff bodies) may cause pericarditis, myocarditis or endocarditis (pancarditis). Vegetations (verrucae) along lines of closure on the cusps. There is leaflet thickening, commusural fusion, shortening, thickening and fusion of tendinous cords. Chronic almost always affects the mitral valve (alone in 65-70%), also with aortic valve in 25%; uncommonly tricuspid valve, pulmonary valve. Fibrous bridging -> fish mouth or buttonhole stenoses. May progress to chronic RHD. Fibrotic valvular disease esp MS

Cardiac Masses

Transthoracic echocardiogarphy has difficulty evaluating apical, pericardial or paracardiac masses. DDx moderator bands, papillary muscles. Most masses don’t deform the outer cardiac borders.

Mural thrombi (most common) – usually LA (AF, rheumatic heart disease) or LV (recent MI, ventricular aneurysm, dilated cardiomyopathy). Low MR signal cf tumour (except calcified myxoma), doesn’t enhance (best differentiated on late ce-CMR).

Benign tumours

  • Myxoma (50%) – Benign. 30-60yo, fever, anaemia, weight loss, emboli, syncope. Any chamber but 90% in atria (atrial myxoma) with L:R 4:1, esp attached to fossa ovalis of atrial septum. Causes chamber enlargement, pulmonary venous HTN, ossific pulmonary nodules. May prolapse into LV during diastole. May be pedunculated, smooth or lobulated/villous. Reduced E-F slope. Calcification in 50%. MRI low T1, high T2, tends to be low on GRE, enhances. 10% have familial syndrome of Carney complex (AD, multiple cardiac and extracardiac myxomas, pigmented skin lesions, endocrine overactivity).
  • Lipoma – Subendocardium, subepicardium or myocardium. Asymptomatic, ball-valve obstructions or arrhythmias. Most LV, RA or atrial septum. DDx lipomatous hypertrophy of the atrial septum (non-neoplastic brown fat deposition ithat may be FDG avid).
  • Rhabdomyoma – Most common in infants and children causing obstrucdtion. ?Harmartoma rather than true neoplasm. Often regresses spontaneously. May be associated with tuberous sclerois.
  • Papillary fibroelastoma – Usually incidental, sea-anemone-like with hairlike projections. May embolise, but usually benign. Usually on valves on the inflow aspect. Calcify in 12%.
  • Teratoma (rare)

Malignant tumours – Primary tend to involve myocardium and endocardium; secondary tend to involve pericardium or epicardium.

  • Metastases – 10-20x more common than primary malignant tumours. From lung (most common), leukaemia, lymphoma (NHL), melanoma, RCC (via IVC), breast. RA and RV more common. Focal or diffusely infiltrating mass.
  • Angiosarcoma
  • Rhabdosarcoma
  • Liposarcoma

Pericardium

Pericardial Effusion

Norrmal pericardial fluid is 20mL, effusion when >50mL, detected on echo at <50mL, XR at ~200mL. Pericardial stripe (between mediastinal and epicardial fat) >4mm, but only seen in ~15% on lat. Differential density sign – lucency along L heart border on PA or posterior border on lat. Globular/sac/water-bottle-shape to heart on PA. Causes include:

  • Idiopathic
  • Infectious – Viral (Coxsackie, echovirus, adenovirus), bactearial (Staph, Strep, H.influenza), fungal (candida, aspergillus, nocardia), mycobacterial
  • Autoimmune – SLE, RA, scleroderma, Dressler syndrome
  • Neoplastic – Lymphoma, lung, breast mets
  • Drugs – Procainamide, hydralazine, phenytoin
  • Metabolic – Uremia, myxoedema, cholesterol
  • Miscellaneous – CHF, aortic dissection, sarcoid, pancreatitis, trauma, radiotherapy

Cardiac tamponade – Chamber compression from pericardium under tension. Pulsus paradoxus with paradoxical septal motion during RV filling, marked jugular vein distension. Rapid enlargement of the heart.

Pneumopericardium causes lucency around the heart with lateral thin line of pericardium. Gas may extend along PAs, under heart. Limited by proximal aorta and MPA superiorly, usually air-fluid level (mediastinal gas not mobile). From trauma, infection, pneumomediastinum.

Acute Pericarditis

  • Serous pericarditis – Non-infectious eg RA, SLE, scleroderma, tumours, uraemia, adjacent infection (eg pleuritis).
  • Fibrinous and serofibrinous pericarditis (most) – Acute MI, Dressler syndrome, uraemia, radiotherapy, rheumatic fever, rheumatological disorders (SLE, RA, scleroderma, AS, psoriasis), trauma, cardiac surgery. Fine granular roughening with turbid fluid. Loud friction rub.
  • Purulent/suppurative pericarditis – May extend into mediastinum (mediastinopericarditis). Organisation by scarring with later constrictive pericarditis. Marked fever.
  • Haemorrhagic pericarditis – Blood with fibrinous or suppurative effusion. Most from malignancy, others bacterial infections, bleeding diathesis, TB, cardiac surgery.
  • Caseous pericarditits – Rare, from TB or less likely fungal infection. Direct spread from tracheobronchial nodes.

Most organise producing plaque-like fibrous thickening or delicate adhesions (adhesive pericarditis), usually with no effect on cardiac function. Some may cause constrictive pericarditis.

Constrictive Pericarditis

Dense fibrous or fibrocalcific scar of the pericardium 5-10mm, reducing ventricular filling. 30-50yo, M>F. From postpericardiotomy, viruses (Coxsackie B), TB, CRF, RA, neoplasm or radiation pericarditis. Common in the setting of previous sternotomy. Calcification in 50%, pleural effusions, ascites. Dilated atria (RA>54mm, LA>40mm) and systemic veins (IVC>22mm), normal/small ventricles. Ventricles may have concave borders, flat RH border. Increased LVEF with small EDV, thickened pericardium ± calcification, abnormal septal motion. Effusive constrictive pericarditis associated with effusion. Tagged CMR may show absent slippage of the pericardium along the epicardium. Tx pericardiectomy.

Pericardial Cysts

Most common cardiophrenic angles, R>L. Usually asymptomatic, M>F. Cysts attached to parietal pericardium, lined by epithelial or mesothelial cells, 30-80mm, occasionally communicates with pericardial space, 20-40HU, don’t enhance, low T1, high T2. DDx fat pad, lipoma, LN, hernia, aneurysm.

Congenital Absence of the Pericardium

M>F, detected at any age. Complete left-sided absence, foraminal defects or total absence. May be associated with bronchogenic cyts, VSD, hernias, sequestration. Heart may be shifted to left, prominent bulge/herniations at RVOT, MPA and LA appendage. Lung insinuates into AP window and beneath heart. Widely swinging heart on decubitus views. Partial absence has the risk of strangulation and sudden death.

Pulmonary Vascular

Enlarged pulmonary outflow tract – From L->R shunt, poststenotic dilatation (pulmonary stenosis), PAH, Marfan syndrome, Takayasu arteritis or idiopathic.

  • Idiopathic dilatation of the pulmonary artery – F>M, mild systolic ejection murmor, dilated MPA but normal peripheral arteries and no pulmonary stenosis.

Pulmonary Embolism

Mortality of untreated PE 30% cf 10-16% treated. Almost always embolic, 95% originate from leg/pelvis DVT. Risk factors include prolonged immobilisation, surgery (esp pelvic/hip), prior PE, pre-existing cardiac disease, oestrogen, smoking, hypercoagulable states (cancer, genetic thrombophilia). 75% occur in the lower lobes, multiple in >50%. Classic triad of dyspnoea, haemoptysis, pleuritic chest pain in <20%. 10% of PEs cause infarction, higher in underlying HF due to limited bronchial a flow. Low suspicion -> D-Dimer; intermediate -> CTPA; high and normal CXR -> V/Q. In patients with an underlying predisposing condition, recurrent embolus in 30%.

Wells score for PE probability: >4 PE likely (consider imaging), <4 unlikely (consider D-dimer to rule out)

  • Clinically suspected DVT – 3.0 points
  • Alternative diagnosis is less likely than PE – 3.0 points
  • Tachycardia – 1.5 points
  • Immobilization/surgery in previous four weeks – 1.5 points
  • History of DVT or PE – 1.5 points
  • Hemoptysis – 1.0 points
  • Malignancy (treatment for within 6 months, palliative) – 1.0 points

CXR normal in 40%, may show localized peripheral oligaemia (Westermark sign, rarely seen), adhesive atelectasis & volume loss (ischaemia to type 2 pneumocytes, surfactant deficiency), wedge-shaped pleurally based homogeneous opacity without air bronchograms (Hampton hump, infarct/haemorrhage, usually posterior or lateral costophrenic sulcus), pleural effusion, enlarged PAs, R heart enlargement.

V/Q Scan

MDCT CTPA sensitivity 73-97%, specificity 87-97%, neg predictive value >95%. Acute PE is a a well-defined central intraluminal filling defect (unless saddle) with convex margins, increased calibre of an occluded vessel. Chornic PE (>3/12) is eccentric, concave margin, reduced calibre of an occluded vessel, webs, bands. Rarely high attenuation thrombus on unenhanced CT. Density of thrombus always <100 HU (cf artifact). Since MDCT CTPA has been used there has been increased diagnosis of PE without any corresponding reduction in mortality (hence be wary of overcalling PE), 5% of non-selected patients have incidental isolated segmental/subsegmental PE. False positives include:

  • Motion artifact – esp adjacent to heart, lung bases. Look at lung windows.
  • Streak artifact – beam hardening from contrast-filled SVC, PICC/pacemaker. Linear.
  • Partial voluming from prominent hilar LN
  • Mixing/slow flow – ill-defined ‘smoke’ (cf well-defined PE).
    • Transient interruption of  contrast column (TICC) from inspiration resulting in unopacified blood from IVC.
    • Bronchial inflow of nonopacified blood; anastomoses with PA at segmental level.
    • Areas of increased PA resistance from consolidation or atelectasis.
  • Pulmonary vein, mucous filled bronchi.
  • PA sarcoma – very large expanding vessel, out of proportion of patient’s clinical status.

Pulmonary angiography sensitivity 98-99%, but for subsegmental PE ~66%. PE when intraluminal filling defect or trailing end of occluding thrombus is outlined by contrast. Secondary signs include prolonged arterial phase, reduced/abnormal parenchymal stain, presence of collateral vessels, delayed venous phase. Allows visualisation of pelvic veins and IVC, pulmonary and RH pressures, IVC filter insertion, thrombolysis.

Pulmonary infarcts are wedge-shaped, peripheral, consisting of haemorrhage. Peripheral higher density more confluent consolidation with central lower density GGO. Absent air bronchograms, non-enhancing lung. Pleural effusion in 1/3. Hampton’s hump is peripheral consolidation/infarct.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

5% of patients with acute PE develop CTEPH; may have no known episode of PE. Suggested from CT/MR, confirmed with pulmonary angiography. Webs, luminal irregularities, abrupt vessel narrowing/obstruction, PAH. Mosaic attenuation with hypodense lung being hypoperfused, small vessels. Peripheral scarring. Usually bilateral. V/Q scan useful. Rx pulmonary endarterectomy.

Nonthrombotic Pulmonary Embolism

May be endogenous or exogenous, macroscopic or microscopic. Aspiration cytology can be obtained from wedged PA occlusion (Swan-Ganz) catheter. Causes include:

  • Air – venous catheter
  • Fat embolism – microsopic emoboli from 10% of long bone fracture. Symptoms 24-72hrs after fracture including respiratory failure, petechiae, retinal haemorrhages (sensitive), neurological signs. Chemical pneumonitis with lipids broken down into fatty acids in the lung. Oedema/ARDs pattern, patchy ground glass opacities, peripheral centrilobular ground glass nodules. Very rarely may seen a macroscopic fat embolus within a vessel. Resolves within one week.
  • Amniotic fluid embolism – microscopic emboli, inciting inflammatory response in PAs causing vasoconstriction, right heart strain. Abrupt SOB, shock, 50% mortality within 1hr. Oedema/ARDS pattern.
  • Silicone embolism – microsopic chemical pneumonitis similar to amniotic fluid.
  • Excipient lung (‘drug-abuser’s lung’) – inert binder from pills crushed and intravenously injected. RH failure, centrilobular nodules, tree-in-bud, diffuse GGO, confluent masses.
  • Methylmethacrylate – post vetebroplasty, may see tract of the methylmethacrylate in the paravertebral venous plexus.
  • Radioactive seed implant – post prostate brahcytherapy. Usually of no clinical significance.
  • Tumour emboli from lung, breast cancer, hepatoma, GI malignancy
    • Intravascular metastases. Vascular tree-in-bud with beaded branching opacities that enlarge.
    • Tumour thrombotic microangiopathy – intimal proliferation and inflammation causing occlusion of aterioles, elevated pulmonary pressures. Tiny centrilobular nodules, pulmonary hypertension.
  • Septic emboli – peripheral nodules 1-3cm, thick cavities with ground glass opacity, air-fluid levels.

Pulmonary Hypertension

PA pressure >25mmHg. RV enlargement (RV:LV > 1:1, bowing of IV septum) caused by acute pressure overload (right heart strain) or volume overload (acute or chronic). Enlarged central PAs, tapering rapidly with diminutive peripheral vessels (pruning), RV enlargement (prominent ant-sup margin on lateral obliterating retrosternal space; hypertrophy -> dilatation -> failure/cor pulmonale), PA atherosclerosis and calcification (severe, rare, pathognomonic), interlobar PA > bronchus intermedius (>15-16mm), MPA >29mm (DDx CO, thyrotoxicosis), segmental PA:bronchus ration >1:1 in all 3 lobes, corkscrew peripheral arteries, centrilobular GGN, mosaic attenuation, enlarged azygos vein. RV hypertrophy with wall >4mm suggest chronic hypertension. MRI gold standard fro quantifying right heart function. Pulmonary arterial hypertension is a subtype of pulmonary hypertension. 2013 Nice classification:

  1. Pulmonary arterial hypertension – Medial hypertrophy, intimal proliferation and fibrosis of muscular and elastic arteries, PA atheromas
    • Idiopathic PAH
    • Heritable PAH
    • Drugs, toxins
    • Associated with connective tissue disease, shunts (ASD, VSD, PDA, PAPVR), HIV, portal hypertension, schistosomiasis.
      • Eisenmenger’s syndrome – L->R shunt -> PAH (enlarged central and peripheral PA, plethora) -> scarring of capillary beds, media hyperplasia and intimal fibrosis (tapering of vessels) -> increased resistance -> R->L shunt. Increased viscosity (polycythaemia and immature RBC) and damaged capillary beds -> haemorrhage and thrombi.
    • Category 1′
      • Pulmonary veno-occlusive disease (PVOD) – Obliterated venules -> interstitial oedema.
      • Pulmonary capillary haemangiomatosis (PCH) – Proliferation of capillaries -> venular obstruction with centrilobular GGO, septal thickening.
  2. Left heart disease – LV systolic/diastolic dysfunction, valvular disease (mitral stenosis), congenital heart dsiease (acquired inflow/outflow obstruction, congenital cardiomyopathy). Treatment aimed at managing underlying left heart disease.
  3. Hypoxaemic lung disease – COPD, ILD, CF, obesity, sleep apnoea, chronic high altitude
  4. Chronic thromboembolic disease – Potentially curable cause of PH. Focal stenoses, bandlike/weblike filling defects, eccentric wall thickening, mosaic attenuation (hyperlucent oligaemia). V/Q scan
  5. Multifactorial, unclear mechanism – haematological, systemic (sarcoid, LCH, LAM), metabolic, others (tumour obstruction, fibrosing mediastinitis, CRF).

Pulmonary Venous Hypertension

Causes include:

  • LVF
  • Mitral stenosis or regurgitation
  • Aortic stenosis or regurgitation
  • Pulmonary veno-occlusive disaese
  • Congenital heart disease

Pulmonary Arteriovenous Malformations (PAVMs)

Direct low-pressure artery-vein fistulas in lung. Associated with HHT in 60-90%, trauma, aneurysm, infection, tumour or spontaneous. Multiple in 35%. Lesions <20mm usually no Sx, greater in multiple PAVMs, including epistaxis (from HHT), dyspnoea, paradoxical emboli to CNS (strokes, abscess, TIA, migraines), haemoptysis. Classified as simple (1 artery-1 vein) or complex (multiple a/v). Tx transcatheter embolotherapy success >98%, Cx paradoxical embolisation of the coil, self-limiting pleurisy.

Pulmonary Vein Mapping

Pulmonary venous anatomy and sizing performed before and after radiofrequency ablation for atrial fibrillation. RF ablation may cause pulmonary vein stenosis as an uncommon complication.

Sinus of Valsalva Aneurysm

Curvilinear calcification anterolateral to ascending aorta.