In ACS patients with hemodynamic instability, their hemodynamic condition may get worse and develop profound cardiogenic shock prior to or during PCI [27]. In this situation, not only the IABP support is required (Fig. 25.2), but the extra-corporeal membrane oxygenator (ECMO) (Fig. 25.2) [28, 29] or other left ventricular assistant devices (LVADs) [30] may be required to promptly stabilize the patient’s blood pressure. In this way, the both femoral arterial routes will be utilized for these circulatory mechanical supports and PCI must be performed from TRA. In case the radial artery diameter is too small, it may mean that the ulnar artery may be the dominant artery of the forearm and ulnar arterial access should be considered. Finally, if the ulnar artery approach is difficult, then brachial arterial approach should be considered.

Correct needle puncture into the right position of the radial artery is no doubt the first step of the successful procedure. However, even if the puncture needle is already inside the radial artery, the guide wire that comes with the sheath system may not be able to be advanced into the true lumen of the artery. In this way, the operator can try to use 0.014″ PCI wire (Fig. 25.3a), followed by utilization of the 6 French (Fig. 25.3b) (but not the 7 French) Terumo arterial sheath (TERUMO Interventional systems).

In some cases, the communication between the proximal end of right radial artery and the distal end of the right brachial artery is very tortuosity or even forms a loop. In this situation, operator can utilize a suitable fluoroscopic view, followed by contrast injection to identify the anatomy of the vessels. The 0.035″ hydrophilic Terumo wire (TERUMO Interventional systems) should be used first to attempt crossing the anatomical difficulty. If fails, a PCI 0.014″ coronary guide wire can be used to solve the problem. After the guide wire crossed the anatomical difficulty, a smaller and soft guiding catheter should be used along the guide wire and advance gently with a twisting action to cross the anatomical difficulty. The 0.014″ guide wire are then be replaced by the 0.035″ wire to support the advancement of the guiding catheter to the ascending aorta for engagement of left and right coronary arteries.

In some cases, especially in those very thin and obese patients with history of hypertension, tortuosity at the proximal end of innominate artery often occurs. In this situation, the using the 0.035″ hydrophilic Terumo wire and taking a deep breath by patient is usually an effective method for the wire to cross the tortuosity and entrances into the ascending aorta, followed by advancing the guiding catheter along the wire into the destination. Sometimes, a big angulation may appear at the aortic root when left TRA is utilized. This situation will increase the difficulty in engaging the coronary arteries. A soft guiding catheter along a hard guide wire is recommended in this situation.

Whether the PCI procedure can be successfully achieved, the first key step is that the guiding catheter is able to offer a good support. Therefore, how to select a suitable guiding catheter is extremely important. Currently, many new guiding catheters with different purposes have been developed. Thus how to choose a good guiding catheter for the PCI procedure is mainly dependent on the operators’ experience and the available instruments in their catheterization laboratories. Some centers would like to use the Kimny (Boston Scientific), Ikari (Boston Scientific), Amplatz (Medtronic, INC.) guiding catheters for right coronary artery intervention and Kimny (Boston Scientific), Ikari (Boston Scientific), Amplatz (Medtronic, INC.) and Launcher (EBU 3.5, 3.75 or 4.0) (Medtronic INC.) guiding catheters for left-side coronary artery intervention since these guiding catheters often offer good support interventional tools.

In the setting of unstable hemodynamic condition, femoral arterial approach of circulatory mechanical support is usually required [28–31]. These mechanical circulatory supports, for example: simultaneous IABP and ECMO have already occupied both femoral arterial routes [28–31]. Furthermore, both radial artery pulses may be too weak that are difficult to be found due to hypoperfusion or had severe atherosclerotic stenosis in some patients. In this circumstances, the brachial arterial approach (i.e., at the level of elbow area) would be the last resort for arterial access. Furthermore, in our clinical practice, it is not rare to find that patients would have both common iliac or femoral artery occlusion as well as unstable hemodynamic condition. In this situation, the right brachial artery approach for implantation of IABP is also the only arterial access for the patients [32].

Anatomically the brachial area is surrounded by abundant soft tissue. Thus, if the method of homeostasis is not appropriate, the puncture site will develop vascular complication with extremely swelling and even haematoma formation [33]. Several methods could be used to avoid these complications. Firstly, try to avoid the puncture needle passing through the posterior wall of the artery. Secondly, the physician should check the ACT and administer an appropriate dosage of protamine for reversing the heparin effect prior to remove the arterial sheath. Thirdly, the puncture site should be compressed manually (i.e., compressed by applying a firm finger pressure) until the bleeding is completely stopped. Fourthly, utilization of new artificial accessory instrument, for example, Hemostatic Bandage (QuickClot^R Interventional^TM, Z-Medica LLC), could be useful.

Mechanically-supported PCI is widely accepted for those ACS patients with unstable hemodynamic condition or cardiogenic shock upon presentation [27–31, 34–36]. In addition, prophylactic IABP support (i.e., as a bridge) for left main or multiple-vessel coronary intervention has recently been shown to offer an additional benefit for those patients who have left ventricular systolic dysfunction (i.e., ejection fraction ≤35 %) with or without congestive heart failure [31]. The results of these observational studies have provided good experience as the reference for our clinical practice [27–31, 34–36].

In order to get the maximal arterial pulse augmentation by IABP, the tip of balloon should be placed at the end of the aortic arch (i.e., at the beginning of the thoracic descending aorta). Also, the arterial waveform should be checked after implantation of IABP and optimized by adjusting the deflation and inflation button. If the waveform is not clear, then normal saline flushing is required. The electrocardiogram leads must be firmed attached in the appropriate positions to provide good synchronization of the balloon timing.

Some particular complications that may occur during the implantation of IABP must be detected early. Firstly, perforation of femoral, external iliac or common iliac arteries will more likely to occur in those patients with very tortuous arterial access route over the inguinal region or lower abdominal aorta. Such complication will cause acute blood loss, retroperitoneal hematoma and deterioration of blood pressure. Thus, careful and gentle approach for arterial puncture and IABP sheath implantation should always be exercised even at the emergent procedure to avoid these complications. Secondly, arterial venous fistula is not infrequent to occur, especially in some patients who’s anatomical distribution of femoral artery and femoral vein may overlap (i.e., the femoral vein goes above the femoral artery) or very close of each other. Quick vascular ultrasound assessment will be helpful if there is any doubt in the location of the femoral vein in relation to the femoral artery. Thirdly, venous sheath or IABP sheath may pass through both femoral vein and artery simultaneously. This is the result of a rare complication that the puncture needle goes through the vein and artery that could be discovered under the fluoroscopy guidance. Lastly, it is not uncommon to find critical ischemia of the lower limb after IABP implantation. This is almost always due to the result of severe iliofemoral atherosclerosis and/or obstruction of IABP sheath implantation site. All of these complications should be promptly identified and dealt with by the active input of vascular surgeons.

Patients put on IABP support should be taken care according to the guidelines and protocols of the coronary care units. These include regular follow up of the vital signs, urine output, the biochemistry (renal and liver function, electrolytes), complete blood count with differential count, chest X-ray, 12-lead electrocardiogram, cardiac enzymes, transthoracic echocardiography, oxygen saturation, and pulmonary capillary wedge pressure measurement by the Swan-Ganz catheter, as well as paying attention to bleeding complications. Furthermore, wound care, early identification and treatment of infection, as well as regular assessment of the perfusion of the lower extremities are particular important.

In those patients undergoing PCI with prophylactic IABP supported, the IABP should be removed a few hours or at least within 24 h after PCI. In this situation, early removal of IABP is safe to the patients. In those patients who have ACS with unstable hemodynamics or cardiogenic shock undergoing early or primary PCI, timing for IABP weaning/removal should be individualized and is mainly dependent on the clinical condition of the patient. Serial assessment of left ventricular function by echocardiograph, pulmonary capillary wedge pressure, cardiac output/cardiac index, urine output and chest X-ray are the important parameters that guide the optimal timing of weaning of IABP. In general, 3–5 days after PCI may be a suitable time line for weaning of IABP as this is the critical time interval of recovery from myocardial stunning. Of various parameters, the clinical information is the utmost important guide for weaning of IABP.

Some patients may promptly develop congestive heart failure (CHF) and acute pulmonary edema after removing the IABP support. The commonest period of developing acute pulmonary edema usually occurs at days 3–5 after removing IABP. There are some clinically relevant parameters may provide important information for predicting CHF, including severe left ventricular dysfunction, difficultly in weaning off the IABP, increased left ventricular end-diastolic pressure/pulmonary capillary wedge pressure, pulmonary hypertension, ischemia-related mitral regurgitation, atrial fibrillation, decrease in urine output, hypotension, low cardiac index, and advance age of >80 years old.

Previous studies have revealed that in STEMI patients complicated by profound cardiogenic shock, IABP-supported primary PCI did not improve clinical outcome when compared with non-IABP-assisted primary PCI [27]. On the other hand, study has demonstrated that early ECMO-assisted primary PCI improved 30-day outcome in AMI patients complicated by cardiogenic shock [28]. Growing evidence have also supported the concept that ECMO offered additional benefit for improving the prognosis in ACS patients with compromised hemodynamics who underwent PCI [37–40].

Clinical observational study has revealed that not all the cardiogenic shock patients undergoing primary PCI will benefit from ECMO support, but only seen in those with profound cardiogenic shock [28]. Thus, ECMO support is highly selected for patients profound cardiogenic shock undergoing primary PCI, or in the setting of acute refractory heart failure and post-cardiac arrest [41–43].

Definitions of cardiogenic shock and profound shock have been described in the previous report [27]. In brief, patients who experience cardiogenic shock upon presentation or to be observed at catheterization laboratory meet the following prospectively defined criteria for early cardiogenic shock: (1) Chest X-ray showing pulmonary edema with systolic blood pressure (SBP) <90 mmHg, or, (2) Persistent hypotension with SBP <90 mmHg associated with low cardiac output and clear lung fields, not related to cardiac arrhythmia, showing no response to adequate fluid supply, and requiring inotropic infusion. Profound cardiogenic shock was defined as SBP <75 mmHg despite intravenous inotropic infusion and IABP support which is associated with altered mental status and respiratory failure [27, 28].