Cardiogenic Shock - Diagnosis and Treatment

158 Part V / Valvular Heart Disease
and associated valvular and myocardial diseases may trigger cardiogenic shock in the
patient with severe AS. When left ventricular systolic dysfunction is caused by
increased afterload (i.e., “afterload mismatch”) with normal myocardial contractility,
systolic function is expected to improve after relief of outflow obstruction. Even with
superimposed myocardial dysfunction, ventricular performance may improve,
although to a lesser extent, after relief of outflow obstruction.
INCIDENCE
The incidence of cardiogenic shock in patients with AS is unknown but is probably
low in the current era because interventions to relieve aortic valvular obstruction
(before severe progressive heart failure or shock develops) are performed at an earlier
stage. In the NHLBI registry of percutaneous balloon aortic valvuloplasty (PBAV) for
aortic valve stenosis, 39 (6%) of 674 patients were in cardiogenic shock (18). A rapid
diagnosis of this situation is very important, because emergency interventions such as
valve replacement or PBAV can be lifesaving and are the only alternatives for these
critical high-risk patients. Most information regarding cardiogenic shock resulting
from critical AS is derived from several reports on the presentation and outcome of
emergency PBAV (19–27).
CLINICAL PRESENTATION
The classic symptoms of severe AS include angina, a gradual decrease in exercise
tolerance as a consequence of exertional dyspnea or fatigue, and syncope. Some
patients present with sudden onset of heart failure, including pulmonary edema and
cardiogenic shock. These manifestations are often related to an acute infection, acute
myocardial ischemia or infarction, anemia, or other causes of hemodynamic stress that
lead to acute decompensation in a previously asymptomatic patient. Other symptoms
such as anasarca, pedal edema, marked fatigability, debilitation, peripheral cyanosis,
and other manifestation of low cardiac output are rare and represent late manifestations
of untreated severe AS.
PHYSICAL EXAMINATION
The classical auscultatory findings of AS are difficult to appreciate in a critically ill
patient with cardiogenic shock. When the left ventricle fails and cardiac output falls,
the murmur becomes softer or disappears altogether. The clinical picture changes to
that of severe left ventricular failure with low cardiac output. Thus, critical AS may be
occult and should be ruled out by echocardiography in every patient presenting with
intractable heart failure or cardiogenic shock.
DIAGNOSIS
Two-dimensional and Doppler echocardiography are the best noninvasive tests for
revealing the various pathological and pathophysiological aspects of aortic stenosis as
well as for assessing the severity of the disease. This is especially true in patients pre-
senting in cardiogenic shock when the classical physical signs and hemodynamic fea-
tures of severe AS are not specific and sometime occult. Two-dimensional
echocardiography provides information about the underlying causes of aortic stenosis
such as bicuspid aortic valve, degenerative calcific stenosis, or changes related to previ-
ous rheumatic fever. Doppler echocardiography provides information regarding trans-
valvular gradients and aortic valve area (using the continuity equation).
Page 1 | Page 2 | Page 3 | Page 4 | Page 5 | Page 6 | Page 7 | Page 8 | Page 9 | Page 10 | Page 11 | Page 12 | Page 13 | Page 14 | Page 15 | Page 16 | Page 17 | Page 18 | Page 19 | Page 20 | Page 21 | Page 22 | Page 23 | Page 24 | Page 25 | Page 26 | Page 27 | Page 28 | Page 29 | Page 30 | Page 31 | Page 32 | Page 33 | Page 34 | Page 35 | Page 36 | Page 37 | Page 38 | Page 39 | Page 40 | Page 41 | Page 42 | Page 43 | Page 44 | Page 45 | Page 46 | Page 47 | Page 48 | Page 49 | Page 50 | Page 51 | Page 52 | Page 53 | Page 54 | Page 55 | Page 56 | Page 57 | Page 58 | Page 59 | Page 60 | Page 61 | Page 62 | Page 63 | Page 64 | Page 65 | Page 66 | Page 67 | Page 68 | Page 69 | Page 70 | Page 71 | Page 72 | Page 73 | Page 74 | Page 75 | Page 76 | Page 77 | Page 78 | Page 79 | Page 80 | Page 81 | Page 82 | Page 83 | Page 84 | Page 85 | Page 86 | Page 87 | Page 88 | Page 89 | Page 90 | Page 91 | Page 92 | Page 93 | Page 94 | Page 95 | Page 96 | Page 97 | Page 98 | Page 99 | Page 100 | Page 101 | Page 102 | Page 103 | Page 104 | Page 105 | Page 106 | Page 107 | Page 108 | Page 109 | Page 110 | Page 111 | Page 112 | Page 113 | Page 114 | Page 115 | Page 116 | Page 117 | Page 118 | Page 119 | Page 120 | Page 121 | Page 122 | Page 123 | Page 124 | Page 125 | Page 126 | Page 127 | Page 128 | Page 129 | Page 130 | Page 131 | Page 132 | Page 133 | Page 134 | Page 135 | Page 136 | Page 137 | Page 138 | Page 139 | Page 140 | Page 141 | Page 142 | Page 143 | Page 144 | Page 145 | Page 146 | Page 147 | Page 148 | Page 149 | Page 150 | Page 151 | Page 152 | Page 153 | Page 154 | Page 155 | Page 156 | Page 157 | Page 158 | Page 159 | Page 160 | Page 161 | Page 162 | Page 163 | Page 164 | Page 165 | Page 166 | Page 167 | Page 168 | Page 169 | Page 170 | Page 171 | Page 172 | Page 173 | Page 174 | Page 175 | Page 176 | Page 177 | Page 178 | Page 179 | Page 180 | Page 181 | Page 182 | Page 183 | Page 184 | Page 185 | Page 186 | Page 187 | Page 188 | Page 189 | Page 190 | Page 191 | Page 192 | Page 193 | Page 194 | Page 195 | Page 196 | Page 197 | Page 198 | Page 199 | Page 200 | Page 201 | Page 202 | Page 203 | Page 204 | Page 205 | Page 206 | Page 207 | Page 208 | Page 209 | Page 210 | Page 211 | Page 212 | Page 213 | Page 214 | Page 215 | Page 216 | Page 217 | Page 218 | Page 219 | Page 220 | Page 221 | Page 222 | Page 223 | Page 224 | Page 225 | Page 226 | Page 227 | Page 228 | Page 229 | Page 230 | Page 231 | Page 232 | Page 233 | Page 234 | Page 235 | Page 236 | Page 237 | Page 238 | Page 239 | Page 240 | Page 241 | Page 242 | Page 243 | Page 244 | Page 245 | Page 246 | Page 247 | Page 248 | Page 249 | Page 250 | Page 251 | Page 252 | Page 253 | Page 254 | Page 255 | Page 256 | Page 257 | Page 258 | Page 259 | Page 260 | Page 261 | Page 262 | Page 263 | Page 264 | Page 265 | Page 266 | Page 267 | Page 268 | Page 269 | Page 270 | Page 271 | Page 272 | Page 273 | Page 274 | Page 275 | Page 276 | Page 277 | Page 278 | Page 279 | Page 280 | Page 281 | Page 282 | Page 283 | Page 284 | Page 285 | Page 286 | Page 287 | Page 288 | Page 289 | Page 290 | Page 291 | Page 292 | Page 293 | Page 294 | Page 295 | Page 296 | Page 297 | Page 298 | Page 299 | Page 300 | Page 301 | Page 302 | Page 303 | Page 304 | Page 305 | Page 306 | Page 307 | Page 308 | Page 309 | Page 310 | Page 311 | Page 312 | Page 313 | Page 314 | Page 315 | Page 316 | Page 317 | Page 318 | Page 319 | Page 320 | Page 321 | Page 322 | Page 323 | Page 324 | Page 325 | Page 326 | Page 327 | Page 328 | Page 329 | Page 330 | Page 331 | Page 332 | Page 333 | Page 334 | Page 335 | Page 336 | Page 337 | Page 338 | Page 339 | Page 340 | Page 341 | Page 342 | Page 343 | Page 344 | Page 345 | Page 346 | Page 347 | Page 348 | Page 349 | Page 350 | Page 351 | Page 352 | Page 353 | Page 354 | Page 355 | Page 356 | Page 357 | Page 358 | Page 359 | Page 360 | Page 361 | Page 362 | Page 363 | Page 364 | Page 365 | Page 366 | Page 367 | Page 368 | Page 369 | Page 370 | Page 371 | Page 372 | Page 373 | Page 374 | Page 375 | Page 376 | Page 377 | Page 378 | Page 379 | Page 380 | Page 381 | Page 382 | Page 383 | Page 384 | Page 385 | Page 386 | Page 387 | Page 388 | Page 389 | Page 390 | Page 391 | Page 392 | Page 393